Description:FIELD OF INVENTION
[001] The subject matter of the present disclosure broadly relates to the field of battery. Particularly, the present disclosure relates to an active material composite and an electrode comprising the active material composite.

BACKGROUND OF THE INVENTION
[002] All-solid-state batteries (ASSB) have advantages over existing liquid electrolyte systems in terms of safety and energy density. This makes them a viable option for next-generation energy storage devices. Halide- and sulfide solid-state electrolytes hold great promise for replacing conventional liquid electrolytes. The sulfide electrolytes enable manufacture of all-solid-state batteries through slurry processing routes and dry processing methodologies due to their potential scalability.
[003] However, the significant reactivity of halide- and sulphide-based electrolytes, such as LPSCl with the transition metal oxide based cathode active material such as nickel manganese cobalt (NMC) poses a serious challenge. NMC reacts with sulfide-based solid electrolytes (SSEs) due to sulfur and oxygen exchange. Hence, a barrier is required to prevent the reactivity between the NMC and SSEs. However, modifications or barrier coating on SSE particles somehow affect the electrochemical performance of the electrolyte. Additionally, another main problem with sulfide electrolytes is that they exhibit chemical and electrochemical stability in a limited voltage window. This voltage window described by electrochemical stability is the range in which the SSE is neither oxidized nor reduced during ASSB operation. The SSEs usually experience an increase in interfacial resistance during cycling due to the chemical instability. This lowers ASSBs’ capacity and cycle life when combined with high voltage cathodes and Li metal anodes.
[004] While employing conventional Li-ion based cathode active materials with sulfide electrolytes, cation interdiffusion during cycling is a significant drawback. High voltage transition metal oxides like LiCoO2 (LCO), LiNixMnyCo(1-x-y)O2 (NMC), and LiNixCoyAl(1-x-y)O2 (NCA) are examples of such Li-ion based cathode active materials. This problem of cation interdiffusion was initially noticed at the interface between LiCoO2 cathode and Li2S20P2S5 electrolyte interface, where cobalt (Co) diffusion from the cathode to the electrolyte was evident after the initial charging. In the case of mixed electrolytes, such as cobalt sulfide (CoS), with lower ionic and higher electronic conductivities the major negative effect is the Co interdiffusion. These diffused Co species cause a large interfacial resistance and short cycle life by driving the electrolyte's continuous degradation at the interface.
[005] Space charge layer formation is another source of instability at the cathode/sulfide interface. The space charge layer is caused by the lithium chemical potential difference between the sulfide electrolyte and the cathode phases, which results in a Li+ depletion zone near the interface of the sulfide SSE.
[006] Hence, an additional improvement is needed to ensure the stability of the cathode-sulfide solid-state electrolyte interfaces.
[007] Therefore, there is a need to develop possible ways to reduce the interfacial instability, by modifying the components of ASSBs.

SUMMARY OF THE INVENTION
[008] In a first aspect of the present disclosure, there is provided an active material composite comprising, (a) an active material, (b) a protective material, and (c) conductive carbon, wherein the active material is coated with a layer of the protective material and a layer of the conductive carbon, and the layer of the protective material is disposed between the active material and the layer of the conductive carbon, wherein the layer of the protective material has a thickness in a range of 100 to 170 nm; and wherein the layer of the conductive carbon has a thickness in a range of 5 to 30 nm.
[009] In a second aspect of the present disclosure, there is provided an electrode film comprising 97 to 98% (w/w) of the active material composite as disclosed herein, and 2 to 3% (w/w) of a fibrillating binder.
[0010] In a third aspect of the present disclosure, there is provided a process for preparing the active material composite, where the process comprises, (a) blending an active material with a protective material followed by calcination to obtain a modified active material, and (b) high shear mixing the modified active material with a conductive carbon to obtain the active material composite.
[0011] In a fourth aspect of the present disclosure, there is provided a cathode comprising the active material composite as disclosed herein.
[0012] In a fifth aspect of the present disclosure, there is provided an electrochemical cell, comprising: a) a cathode comprising the electrode film as disclosed herein b) an anode; and c) an electrolyte.
[0013] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The following drawings form a part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0015] Figure 1 depicts the field emission scanning electron microscopic (FESEM) images of modified active material M-1 in a scale of (a) 2 µm and (b) 1 µm, in accordance with an embodiment of the present disclosure.
[0016] Figure 2 depicts the x-ray diffraction (XRD) pattern of modified active material M-1, in accordance with an embodiment of the present disclosure.
[0017] Figure 3 depicts the Energy Dispersive X-ray Spectroscopy (EDAX) spectral analysis of modified active material M-1, in accordance with an embodiment of the present disclosure.
[0018] Figure 4 depicts the (a) EDS image and (b-i) elemental mapping analysis with respect to (b) oxygen, (c) nickel, (d) phosphorous, (e) cobalt, (f) manganese, (g) titanium, (h) carbon, and (i) aluminium of modified active material M-1, in accordance with an embodiment of the present disclosure.
[0019] Figure 5 (A-C) depicts the FESEM analysis of the active material composite A-1, 5A depicts the FESEM images of active material composite A-1 in a scale of (a) 5 µm and (b) 1 µm; 5B depicts the cross-sectional FESEM images of the cathode film CA-1 on a scale of 20 µm; and 5C depicts the FESEM images of the active material composite A-1 comprising 1% by weight of conductive carbon coated upon particles of modified active material M-1 wherein the encircled portion shows flaky graphitic particles, in accordance with an embodiment of the present disclosure.
[0020] Figure 6 depicts the x-ray diffraction (XRD) pattern of active material composite A-1, in accordance with an embodiment of the present disclosure.
[0021] Figure 7 depicts the EDAX spectral analysis of active material composite A-1, in accordance with an embodiment of the present disclosure.
[0022] Figure 8 depicts the (a) EDS layered image and (b-i) elemental mapping analysis with respect to (b) oxygen, (c) nickel, (d) phosphorous, (e) titanium, (f) aluminium, (g) carbon, (h) cobalt, and (i) manganese, of active material composite A-1, in accordance with an embodiment of the present disclosure.
[0023] Figure 9 depicts the transmission electron microscopic (TEM) images for active material composite A-1 on a scale of (a) 200 nm, (b) 100 nm (c) 20 nm, and (d) 10 nm, in accordance with an embodiment of the present disclosure.
[0024] Figure 10 depicts the FESEM images for the active material composite A-2 on a scale of (a) 5µm and (b) 1µm, in accordance with an embodiment of the present disclosure.
[0025] Figure 11 depicts the XRD analysis for the active material composite A-2, in accordance with an embodiment of the present disclosure.
[0026] Figure 12 depicts the EDAX spectral analysis for the active material composite A-2, in accordance with an embodiment of the present disclosure.
[0027] Figure 13 depicts (a) EDA layered image and (b-h) elemental mapping analysis with respect to (b) oxygen, (c) nickel, (d) carbon, (e) phosphorous, (f) cobalt, (g) manganese, and (h) titanium, for the NMC coated with carbon in the first step active material composite A-2, in accordance with an embodiment of the present disclosure.
[0028] Figure 14 depicts the charge-discharge cycle data of cathode films comprising varying wt% of protective material (LATP) in wet electrode validation, in accordance with an embodiment of the present disclosure.
[0029] Figure 15 depicts the (a) charge-discharge cycle data for cathode film CA-1 via wet electrode validation; and (b) capacity retention with coulombic efficiency data for cathode film CA-1 via wet electrode validation, in accordance with an embodiment of the present disclosure.
[0030] Figure 16 depicts the charge-discharge cycle data via wet electrode validation of (a) cathode film comprising 97.5% of pristine NMC and 2.5% of PVDF; and (b) cathode film CA-1, in accordance with an embodiment of the present disclosure.
[0031] Figure 17 depicts the charge-discharge cycle data for cathode film CA-1 via dry electrode validation, in accordance with an embodiment of the present disclosure.
[0032] Figure 18 depicts the electrochemical impedance spectral (EIS) analysis of modified active material M-1 against lithium phosphorous chloride (LPSCl) electrolyte at (a) room temperature and (b) 60 ?, (c) active material composite A-1, and (d) active material composite A-3, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0033] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions, and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features.
Definitions:
[0034] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are delineated here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.
[0035] The articles “a”, “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.
[0036] The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as “consists of only”.
[0037] Throughout this specification, unless the context requires otherwise the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of element or steps.
[0038] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.
[0039] The term “w/w” means the percentage by weight, relative to the weight of the total composition, unless otherwise specified.
[0040] The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0041] The term “active material” refers to the active constituent of an electrode, which comprises the particles that undergo oxidation or reduction, resulting in reversible ion storage in an electrochemical cell of an energy storage device, such as a battery or a supercapacitor. Examples of active material in the present disclosure include but not limited to Lithium, Nickel-Manganese-Cobalt (NMC), lithium Nickel-Cobalt-Aluminium Oxide (NCA), lithium cobalt oxide (LCO), lithium rich manganese rich oxide (LRMR), and lithium manganese oxide (LMO).
[0042] The term “composite” refers to material that is made up of two or more different substances that are physically or chemically combined together. The composites typically have unique properties and characteristics that are different from the individual components. In an aspect of the present disclosure, there is provided an active material composite comprising a) an active material b) a protective material; and c) a conductive carbon.
[0043] The term “protective material” refers to a material that is used to protect a substance, from damage or corrosion. This protective material may be a coating or a barrier that prevents external factors, such as moisture, chemicals, or contaminants, from affecting the performance and longevity of the substance on which it is coated. In an aspect of the present disclosure, the active material is coated with a layer if protective material to prevent the reaction of the active material with the sulfide-based electrolyte. Examples of the protective material includes but not limited to lithium aluminium titanium phosphorous (LATP), AlPO4, or FePO4.
[0044] The term “conductive carbon” refers to the carbon-based additive added to an electrode composition to enhance the conductivity of the electrode. In an aspect of the present disclosure, the conductive carbon includes but not limited to Super P, Ketjen Black, KS6, graphite, MWCNT, CNT, activated carbon, single-wall carbon nanotube, multi-wall carbon nanotube, graphene, or combinations thereof.
[0045] The term “fibrillating binder” refers to a substance that is capable of forming fibrils, which are thread-like structures formed upon application of high temperature or pressure. The fibrillating binders are commonly used in the production of composite materials, where they help to hold together the different components of the material. The fibrillating binder can increase the strength and durability of the composite material by providing additional cohesion between the various components. In an aspect of present disclosure, the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene polymer (FEP), fluoroethylene vinyl ether (FEVE), or combinations thereof.
[0046] The term “electrolyte” refers to the substance which furnishes ions for electrical conduction between electrodes of an electrochemical cell. In the present disclosure, the term electrolyte includes but not limited Li6PS5Cl (LPSCl), Li10GeP2S12 (LGPS), Li3PS4 (LPS), argyrodite type crystal Li6PS5X (X=Cl, Br or I), or mixtures thereof.
[0047] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
[0048] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0049] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, formulations, and methods are clearly within the scope of the disclosure, as described herein.
[0050] As discussed in the background of the present disclosure, there is a need to develop better solid-state battery with better electrochemical performance and better coulombic efficiency. The utilization of sulfide-based solid electrolyte (SSE) in ASSB is still critical due to its chemical instability with the NMC based cathode materials, because NMC reacts with sulfide-based electrolytes due to Sulfur and Oxygen exchange. These reactions create various irreversible interphases and side products at the cathode-electrolyte particle interface, leading to high interfacial resistance and lower electrochemical performance. Hence, a protective coating is required to prevent the reactivity between the cathode active material (CAM) and solid electrolyte (SE) in an interface between cathode and electrolyte. A cathode dry film with reduced reactivity with solid electrolyte is required for ASSB application. Therefore, there is a need to develop an efficient protective coating to prevent the reactivity between the cathode active material and electrolyte in the interface between cathode and SSE as well as in the bulk of the SSE and stable cathode composition comprising sulfide based solid electrolytes.
[0051] To fulfil all of these aspects of the cathode composition, surface modification of the active material particles has been adopted in the present disclosure as the key resolution to attain better stability without affecting the conductivity and electrochemical performance. Therefore, the present disclosure provides an active material composite having reduced reactivity with sulfide-based solid electrolytes, as required for all-solid-state battery application. In the present disclosure, a dual coating is employed using protective material and conductive carbon over an active material (NMC) surface. A protective material coating upon NMC active material reduces the reactivity with sulfur-based electrolytes. In view of this, the present disclosure provides an active material composite comprising an active material coated with a protective layer comprising a layer each of a protective material and a conductive carbon. The particle size of the components, like NMC ranging from 6 to 10 micron, and the LATP protective material having a particle size in a range of 133 to 140 nm, is also important in achieving an efficient electrode film.
[0052] The present disclosure further provides a convenient yet advantageous process for the preparation of the disclosed cathode composition. In the present disclosure, a protective material LATP is coated upon an active material NMC by high shear mixing using a mini mixer in the first step. In the second step of the process, conductive carbon was coated over the material obtained during the first step using a mini mixer to achieve an active material composite. This composite is the mixed with a fibrillating binder, followed by calendaring to obtain a dry film.
[0053] The order of coating the layers of protective material and conductive carbon upon the active material surface is also important to provide enhanced electrochemical performance. The process of preparing the active material composite as disclosed herein includes the addition of LATP in the first step, followed by carbon, to achieve the desired order of coating for resulting the desired electrochemical efficiency. A particular order of mixing cathode active material, protective material, and conductive carbon(s) has been provided herein. In this process of preparation of the active material composite, mixing of cathode active material, protective material and conductive carbons have been performed in sequential steps, wherein the sequence of addition of conductive carbon(s) into the active material was achieved only after the addition of LATP. The LATP/NMC provides a rough surface that provides binding sites for carbon on the cathode active material surface. Further, the carbon coating as the outermost layer acts as an anchoring agent to provide an electrode film with desired thickness, porosity, and tensile strength.
[0054] Accordingly, the present disclosure provides an active material composite comprising a) an active material; b) a protective material; and c) a conductive carbon, wherein the active material is coated with a layer of the protective material and a layer of the conductive carbon; and wherein the layer of the protective material is disposed between the active material and the layer of the conductive carbon. The present disclosure also provides a process for preparing the active material composite as disclosed herein.
[0055] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0056] In an embodiment of the present disclosure, there is provided an active material composite comprising, (a) an active material; (a) a protective material; and (c) a conductive carbon, where the active material is coated with a layer of the protective material and a layer of the conductive carbon, and the layer of the protective material is disposed between the active material and the layer of the conductive carbon; and the layer of the protective material has a thickness in a range of 100 to 170 nm, whereas the layer of the conductive carbon has a thickness in a range of 5 to 30 nm. In another embodiment of the present disclosure, the layer of the protective material has a thickness in a range of 110 to 160 nm, and the layer of the conductive carbon has a thickness in a range of 7 to 25 nm. In yet another embodiment of the present disclosure, the protective material has a thickness in a range of 120 to 159 nm, and the layer of the conductive carbon has a thickness in a range of 8 to 10 nm.
[0057] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the active material is in a weight range of 96.5 to 98.5% (w/w); and is selected from lithium nickel manganese cobalt (NMC), lithium nickel-cobalt-aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium rich manganese rich oxide (LRMR), lithium manganese oxide (LMO) or combinations thereof. In another embodiment of the present disclosure, the active material is in a weight range of 97 to 98% and is selected from nickel manganese cobalt (NMC).
[0058] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the active material has a particle size in a range of 4 to 15 µm; and the protective material has a particle size in a range of 120 to 200 nm and ionic conductivity in a range of 1 × 10-4 to 2 × 10-4 S/cm. In another embodiment of the present disclosure, the active material has a particle size in the range of 5.5 to 12.5 µm; and the protective material has a particle size in a range of 130 to 185 nm and ionic conductivity in a range of 1 × 10-4 to 1.7 × 10-4 S/cm. In yet another embodiment of the present disclosure, the active material having a particle size in the range of 6.2 to 11.7 µm, and the protective material has a particle size in a range of 135 to 155 nm and ionic conductivity in a range of 1 × 10-4 to 1.6 × 10-4 S/cm.
[0059] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the protective material is in a weight range of 1 to 2% (w/w); and is selected from lithium aluminium titanium phosphate (LATP), aluminium phosphate, iron phosphate, or combinations thereof. In another embodiment of the present disclosure, the protective material is in a weight range of 1.3 to 1.6% (w/w); and is selected from lithium aluminium titanium phosphate (LATP) or aluminium phosphate. In yet another embodiment of the present disclosure, the protective material is in a weight range of 1.45 to 1.55% (w/w); and is lithium aluminium titanium phosphate (LATP).
[0060] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the conductive carbon is in a weight range of 0.5 to 1.5% (w/w); and is selected from carbon black (such as Ketjen Black, Super P) graphite (such as KS6, KS15L) activated carbon, single-wall carbon nanotube, multi-wall carbon nanotube, graphene, or combinations thereof. In another embodiment of the present invention, there is provided that conductive carbon is in a weight range of 0.8 to 1.2% (w/w); and is selected from carbon black (such as Ketjen black, Super P), graphite (KS6, KS15L), activated carbon, single-wall carbon nanotube, multi-wall carbon nanotube, graphene. In yet another embodiment of the present disclosure, the conductive carbon is in a weight range of 0.85 to 1.05% (w/w); and is selected from Ketjen Black, KS6, or combinations.
[0061] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the active material composite having a particle size in a range of 4 to 15 µm. In another embodiment of the present disclosure, the active material composite has a particle size in a range of 5.5 to 12.5 µm. In yet another embodiment of the present disclosure, the active material composite has a particle size in a range of 6.2 to 11 µm. In yet another embodiment of the present disclosure, the active material composite has a particle size in a range of 9 to 11 µm.
[0062] In an embodiment of the present disclosure, there is provided an electrode film comprising 97 to 98% (w/w) of the active material composite as disclosed herein, and 2 to 3% (w/w) of a fibrillating binder. In another embodiment of the present disclosure, there is provided an electrode film comprising 97.25 to 97.75% (w/w) of the active material composite as disclosed herein, and 2.25 to 2.75% (w/w) of a fibrillating binder.
[0063] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene polymer (FEP), fluoroethylene vinyl ether (FEVE), or combinations thereof. In another embodiment of the present disclosure, the fibrillating binder is polytetrafluoroethylene (PTFE).
[0064] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film has a thickness in a range of 50 to 100 µm; and a porosity in a range of 0 to 2%. In another embodiment of the present disclosure, there is provided that the electrode film has a thickness in a range of 55 to 90 µm; and a porosity in a range of 0.1 to 2%. In yet another embodiment of the present disclosure, there is provided that the electrode film has a thickness in a range of 65 to 80 µm.
[0065] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film exhibits a tensile strength in a range of 300 to 350 kgf/cm²; and a resistance in a range of 120 to 150 Ohms. In another embodiment of the present disclosure, the electrode film exhibits a tensile strength in a range of 305 to 340 kgf/cm²; and a resistance in a range of 125 to 150 Ohms. In yet another embodiment of the present disclosure, the electrode film exhibits a tensile strength in a range of 308 to 310 kgf/cm²; and a resistance in a range of 130 to 149 Ohms.
[0066] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film exhibited a specific capacity in a range of 205 to 210 mAh/g and an initial coulombic efficiency in a range of 90 to 95%, in wet electrode validation.
[0067] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film exhibited a specific capacity in a range of 193 to 200 mAh/g and an initial coulombic efficiency in a range of 90 to 95% in dry electrode validation.
[0068] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film exhibits a capacity retention in a range of 93 to 99% up to 50 cycles at 25?.
[0069] In an embodiment of the present disclosure, there is provided an active material composite as disclosed herein, wherein the active material is in a weight range of 96.5 to 98.5% (w/w), has a particle size in a range of 4 to 15 µm and is selected from lithium nickel manganese cobalt (NMC), lithium nickel-cobalt-aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium rich manganese rich oxide (LRMR), lithium manganese oxide (LMO) or combinations thereof. In another embodiment of the present disclosure, the active material is in a weight range of 97 to 98%, has a particle size in the range of 5.5 to 10 µm and is selected from nickel manganese cobalt (NMC), nickel cobalt aluminium (NCA), lithium cobalt oxide (LCO), lithium-rich manganese-rich (LRMR) oxide, or lithium manganese oxide (LMO). In yet another embodiment of the present disclosure, the active material in a weight range of 97.2 to 97.9%, having a particle size in the range of 6 to 9.9 µm and is NMC.
[0070] In an embodiment of the present disclosure, there is provided an active material composite comprising: (a) an active material; (a) a protective material selected from lithium aluminium titanium phosphate (LATP), aluminium phosphate, iron phosphate, or combinations thereof; and (c) a conductive carbon, wherein the active material is coated with a layer of the protective material and a layer of the conductive carbon, and the layer of the protective material is disposed between the active material and the layer of the conductive carbon; and the layer of the protective material has a thickness in a range of 100 to 170 nm, the protective material is in a weight range of 1 to 2% (w/w), the protective material has an ionic conductivity in a range of 1 × 10-4 to 2 × 10-4 S/cm and is selected from lithium aluminium titanium phosphate (LATP), aluminium phosphate, iron phosphate, or combinations thereof. In another embodiment of the present disclosure, the layer of the protective material has a thickness in a range of 110 to 145 nm, and the protective material is in a weight range of 1.1 to 1.9% (w/w) and is selected from lithium aluminium titanium phosphate, or iron phosphate. In yet another embodiment of the present disclosure, the layer of the protective material has a thickness in a range of 120 to140 nm and the protective material is in a weight range of 1.4 to 1.6% (w/w) and is lithium aluminium titanium phosphate (LATP).
[0071] In an embodiment of the present disclosure, there is provided an active material composite comprising, (a) an active material; (a) a protective material; and (c) a conductive carbon selected from carbon black (Ketjen Black, Super P), graphite (KS6, KS15), activated carbon, single-wall carbon nanotube, multi-wall carbon nanotube, graphene, or combinations thereof, wherein the active material is coated with a layer of the protective material and a layer of the conductive carbon, and the layer of the protective material is disposed between the active material and the layer of the conductive carbon; and the layer of the conductive carbon has a thickness in a range of 5 to 30nm, and the conductive carbon is in a weight range of 0.5 to 1.5% (w/w). In another embodiment of the present disclosure, the layer of the conductive carbon has a thickness in a range of 7 to 25nm, and the conductive carbon is in a weight range of 0.8 to 1.2% (w/w), has a particle size in a range of 1 to 40µm, and is selected from Super P, carbon black, graphite, activated carbon, single-wall carbon nanotube, multi-wall carbon nanotube, graphene or combinations thereof. In yet another embodiment of the present disclosure, the layer of the conductive carbon has a thickness in a range of 8 to 10nm, and the conductive carbon is in a weight range of 0.9 to 1.05% (w/w), has a particle size in a range of 3 to 39µm, and is selected from Ketjen Black, KS6, or combinations thereof.
[0072] In an embodiment of the present disclosure, there is provided an electrode film as disclosed herein, wherein the electrode film which exhibits a tensile strength in a range of 300 to 350 kgf/cm², a resistance in a range of 120 to 150 Ohms, specific capacity in a range of 190 to 200 mAh/g and an initial coulombic efficiency in a range of 90 to 95% in dry electrode validation. In another embodiment of the present disclosure, the electrode film exhibits a tensile strength in a range of 305 to 340 kgf/cm², a resistance in a range of 125 to 140 Ohms, specific capacity in a range of 195 to 199 mAh/g and an initial coulombic efficiency in a range of 93 to 95%. In yet another embodiment of the present disclosure, the electrode film exhibits a tensile strength in a range of 308 to 310 kgf/cm²; a resistance in a range of 130 to 139 Ohms, specific capacity in a range of 196 to 197 mAh/g and an initial coulombic efficiency in a range of 93.5 to 95%.
[0073] In an embodiment of the present disclosure, there is provided an electrode film which exhibits a tensile strength in a range of 300 to 350 kgf/cm², resistance in a range of 120 to 150 Ohms, specific capacity in a range of 205 to 210 mAh/g and an initial coulombic efficiency in a range of 90 to 95%, in wet electrode validation. In another embodiment of the present disclosure, the electrode film exhibits a tensile strength in a range of 305 to 340 kgf/cm², a resistance in a range of 125 to 140 Ohms, specific capacity in a range of 206 to 208.5 mAh/g and an initial coulombic efficiency in a range of 90 to 93.5%. In yet another embodiment, the electrode film exhibits a tensile strength in a range of 308 to 310 kgf/cm², a resistance in a range of 130 to 139 Ohms specific capacity in a range of 207 to 208 mAh/g and an initial coulombic efficiency in a range of 90 to 93%.
[0074] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material followed by calcination to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon to obtain the active material composite.
[0075] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the blending in step (a) is carried out at a speed in a range of 2000 to 3500 rpm for a period in a range of 1.5 to 2.5 hours. In another embodiment of the present disclosure, the blending is carried out at a speed in a range of 2200 to 3300 rpm for a period in a range of 1.8 to 2.2 hours. In yet another embodiment of the present disclosure, the blending is carried out at a speed in a range of 2400 to 3000 rpm for a period in a range of 1.9 to 2.1 hours.
[0076] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material at a speed in a range of 2000 to 3500 rpm for a period in a range of 1.5 to 2.5 hours followed by calcination to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon to obtain the active material composite. In another embodiment of the present disclosure, the blending is carried out at a speed in a range of 2200 to 3100 rpm for a period in a range of 1.8 to 2.2 hours. In yet another embodiment of the present disclosure, there is provided that the blending is carried out at a speed in a range of 2400 to 3000 rpm for a period in a range of 1.9 to 2.1 hours.
[0077] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the calcination in step (a) is carried out at a temperature in a range of 200 to 400 ?, for a period in a range of 3 to 5 hours. , in oxygen atmosphere. In another embodiment of the present disclosure, the calcination is carried out at a temperature in a range of 250 to 350 ?, for a period in a range of 3.5 to 4.5 hours, in oxygen atmosphere.
[0078] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material followed by calcination at a temperature in a range of 200 to 400 ?, for a period in a range of 3 to 5 hours to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon to obtain the active material composite. In another embodiment of the present disclosure, there is provided that the calcination is carried out at a temperature in a range of 250 to 350?, for a period in a range of 3.5 to 4 hours.
[0079] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material at a speed in a range of 2000 to 3500 rpm for a period in a range of 1.5 to 2.5 hours, followed by calcination at a temperature in a range of 200 to 400?, for a period in a range of 3 to 5 hours, to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon to obtain the active material composite.
[0080] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein high shear mixing in step (b) is carried out at a speed in a range of 3500 to 4000 rpm for a period in a range of 3 to 5 hours. In another embodiment of the present disclosure, the high shear mixing is carried out at a speed in a range of 3500 to 4000 rpm for a period in a range of 3.5 to 4.5 hours.
[0081] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material followed by calcination to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon at a speed in a range of 3500 to 4000 rpm for a period in a range of 3 to 5 hours to obtain the active material composite. In another embodiment of the present disclosure, high shear mixing is carried out at a speed in a range of 3500 to 4000 rpm for a period in a range of 3.5 to 4.5 hours.
[0082] In an embodiment of the present disclosure, there is provided a process for preparing the active material composite as disclosed herein, the process comprising: (a) blending an active material with a protective material at a speed in a range of 2000 to 3500 rpm for a period in a range of 1.5 to 2.5 hours, followed by calcination at a temperature in a range of 200 to 400 ?, for a period in a range of 3 to 5 hours, to obtain a modified active material; and (b) high shear mixing the modified active material with a conductive carbon at a speed in a range of 3500 to 4000 rpm for a period in a range of 3 to 5 hours to obtain the active material composite.
[0083] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the process further comprises mixing a fibrillating binder with the active material composite at a speed in a range of 1500 to 3000 rpm, at a temperature in a range of 15 to 80?, followed by calendering at a roller speed in a range of 0.5 to 2 m/min at a temperature in a range of 100 to 150?, and for a period in a range of 30 to 200 seconds, to obtain an electrode film. In another embodiment of the present disclosure, the mixing is carried out at a speed in a range of 1900 to 2800 rpm and at a temperature in a range of 16 to 70?, and calendering is carried out at a roller speed in a range of 0.8 to 1.8m/min at a temperature in a range of 110 to 140?, and for a period in a range of 30 to 180 seconds. In yet another embodiment of the present disclosure, there is provided a process wherein the mixing is carried out at a speed in a range of 2000 to 2500 rpm, at a temperature in a range of 45 to 55?, and calendering is carried out at a roller speed in a range of 1 to 1.5m/min at a temperature in a range of 120 to 130?, and for a period in a range of 60 to 180minutes .
[0084] In an embodiment of the present disclosure, there is provided a method of preparing the active material composite, wherein the active material composite is processed to form a film.
[0085] In an embodiment of the present disclosure, there is provided a cathode comprising the active material composite as disclosed herein.
[0086] In an embodiment of the present disclosure, there is provided a cathode comprising 97 to 98% (w/w) of the active material composite as claimed in claim 1, and 2 to 3% (w/w) of a fibrillating binder.
[0087] In an embodiment of the present disclosure, there is provided an electrochemical cell, comprising: a cathode comprising the electrode film, an anode; and an electrolyte. In another embodiment of the present disclosure, the cathode comprises the electrode film coated on an aluminium current collector.
[0088] In an embodiment of the present disclosure, there is provided an electrochemical cell as disclosed herein, where the anode is lithium.
[0089] In an embodiment of the present disclosure, there is provided an electrochemical cell as disclosed herein, where the electrolyte is selected from lithium phosphorus sulfur chloride (LPSCl), lithium germanium thiophosphate (LGPS), lithium thiophosphate (LPS), Lithium phosphorus sulfur halide (LPSX; wherein X is Br, I), or halide based lithium electrolytes, such as lithium indium chloride (LiInCl).
[0090] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.

EXAMPLES
[0091] The disclosure will now be illustrated with following examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply.
EXAMPLE 1
[0092] The present example elaborates the method of preparing the disclosed active material composite.
Preparation of the active material composite A-1 (NMC first coated with LATP and then coated with conductive carbon)
[0093] For purposes of the present disclosure, an active material composite A-1 and a cathode film CA-1 were prepared by the below process.
[0094] The active material composite in the present disclosure comprises a) an active material - LiNi0.8Mn0.1Co0.1O2; b) a protective material - lithium aluminium titanium phosphate (LATP); and c) conductive carbons - Ketjen Black (KB) and KS6L. To prepare the active material composite, the procedure explained below was adopted.
[0095] 1.5 % by weight of LATP (protective material) was coated upon the particles of 97.5% by weight of nickel manganese cobalt (NMC; active material) by blending using a mini mixer at 2500 rpm for 2 hours. The resulting blend was calcined at 300 ? for 4 hours in an oxygen atmosphere to obtain a modified active material M-1. The LATP had a desired ionic conductivity of 10-4 Scm-1 and a particle size of ~139 nm. The NMC material employed for the preparation of active material composite was a bimodal polycrystalline NMC, which had particle size of ~4µm and ~9.7 µm. In the second step, 0.9% by weight of conductive carbon comprising 0.6% by weight of Ketjen Black (KB) and 0.3% by weight of K6SL was coated over the modified active material particles by high shear mixing at 3500 rpm for 4 h using the mini mixer to obtain the active material composite A-1. This active material composite A-1 was then mixed with a fibrillating binder polytetrafluoroethylene (PTFE) at 2000 rpm at a temperature of 15 ?, followed by calendering at a roller speed of 1 m/min, at a temperature of 120 ? for 2 min to obtain an cathode film CA-1 (electrode film) having thickness of ~75 µm, with porosity of less than 2%, and tensile strength value of 309.95 kgf/cm².

I. Characterization of modified active material M-1
[0096] The modified active material M-1 as obtained in the process explained above was characterised to morphologically analyse the coating of LATP on the NMC surface. Structural characterization of the modified active material M-1 was performed using high-resolution X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDAX) and elemental mapping.
a. FESEM and XRD analysis
[0097] FESEM images at a resolution of 1 kV of modified active material M-1 (NMC coated with LATP) obtained by blending NMC and LATP at 2500 rpm for 2 h is given in Figure 1 (a) and (b). The surface without any discontinuities or gaps revealed the uniform coating of LATP over NMC. The active material composite A-1 had a particle size of D50 of 10.7 µm. This uniform coating was confirmed by sharp diffraction peaks exhibited by XRD analysis given in Figure 2. To analyse the structural details such as phase purity, or crystallinity, XRD analysis of the composite was carried out.
[0098] The modified active material exhibited a hexagonal crystal structure with a space group of R-3m. Visible peak splitting is observed at 38° confirmed the layered structure. Since, it was a coating rather than doping, the visible peak splitting was observed at 38° and 65° corresponding to the planes (006/012) and (018/110), respectively. In case of any phase changes or doping, additional peaks would have appeared along with the NMC peaks, and the peak splitting will be absent. Therefore, the formation and existence of NMC without phase changes or doping, was confirmed by peaks at 19°, 37°, 38°, 45°, 48°, 58°, 65°, and 68° values of 2?.
b. EDAX spectrum and elemental mapping
[0099] The EDAX spectrum and elemental mapping for the modified active material M-1 is given in the Figure 3 and Figure 4 respectively. Sharp elemental peaks in EDAX spectrum in Figure 3 indicated the homogenous distribution of LATP over NMC. The absence of any clustering or segregation in Figure 3 also confirmed the uniform coating of LATP over NMC. Further, in the elemental mapping data, the LATP coating on NMC was confirmed by the presence of P, Al, Ti, O that belongs to LATP and Ni, Mn, Co, O from NMC. Hence, the blending step with disclosed parameters were essential for achieving uniform LATP coating on NMC.
[00100] Each element was marked by a particular colour which represent the element present on the surface. The distribution of these colours were found throughout the NMC which confirmed the uniform distribution of the elements. The weight percentage of Al, P, O, and Ti were roughly estimated using the EDAX spectrometer.

II. Characterization of the active material composite A-1
[00101] The active material composite A-1 as obtained by the process explained above herein was subjected to morphological characterization.
a. Field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD) analysis
[00102] The present example provides the FESEM and XRD analysis of the active material composite A-1. The Figure 5 A (a and b) depicts the FESEM images of the surface of the active material composite A-1. The XRD pattern for the active material composite A-1 is provided in Figure 6.
[00103] The XRD pattern for the active material composite A-1 exhibited a hexagonal crystal structure with a space group of R-3m. The carbon coating was an amorphous coating when used in less than 0.9 wt%, hence there was no additional peaks present along with the NMC peeks. Since, it was a coating rather than doping, the visible peak splitting was observed at 38° and 65° corresponding to the planes (006/012) and (018/110) respectively. Similarly, there was no phase changes or doping when LATP was coated. Only NMC peaks were present at 19°, 37°, 38°, 45°, 48°, 58°, 65°, and 68° values of 2?.
[00104] As it was observed in Figure 5A, the coating of LATP upon the NMC particles appeared smooth and more consistent than that in modified active material M-1 as shown in Figure 1 (a). The FESEM cross-sectional image of the cathode film prepared using the cathode film CA-1 is also given in Figure 5B. The thickness of the cathode film CA-1 was analysed to be ~75µm.
b. Energy dispersive X-ray spectroscopy (EDAX) and elemental mapping
[00105] Figure 7 and 8 provides the EDAX spectrum and elemental mapping data respectively, of the active material composite A-1 obtained by high shear mixing at 3500 rpm for 4h. These Figures also confirmed the better homogeneity of LATP coating and conductive carbon coating observed in FESEM and XRD analysis. This indicated that the high shear mixing at 3500 to 4000 rpm for 4 hours was optimum to achieve the active material composite with uniform coating as disclosed herein.
c. Transmission electron microscopic (TEM) analysis
[00106] The active material composite A-1 was characterised using TEM analysis to study coating and adhesion properties of LATP and conductive carbon over the NMC surface.
[00107] The protective material LATP and conductive carbon layer were found to have a combined thickness of 167 nm as shown in the TEM images of the active material composite A-1 depicted in Figure 9 (a). Figure 9 (b) shows the layers of LATP and conductive carbon coated upon the active material surface. The Figures 9 (c) and (d) show the thickness of conductive carbon layer in a range of 8.769 to 9.495 nm. The dark band in the TEM image related to NMC and the lighter band corresponded to LATP and conductive carbon coating. Here, the conductive carbon coating upon the modified active material M-1 (NMC coated with LATP) was seen as an amorphous layer with thickness ranging from 8.769 to 9.495 nm. From this, the thickness of the layer of LATP was calculated to be in a range of 157.565 to 158.291nm.
EXAMPLE 2
Preparation of active material composite A-2 (NMC first coated with carbon and then coated with LATP)
[00108] For comparative purposes, an active material composite A-2 was prepared by coating the active material NMC (97.5%) with 1% by weight of conductive carbon (0.6% (w/w) of KB and 0.4% (w/w) of KS6L) via blending at 2500 rpm for 2 hours to obtain a modified active material M-2. The modified active material M-2 was then high shear mixed with a protective material LATP at 2500 rpm for 2 hours followed by calcining at 300 ? for 4 hours in an oxygen atmosphere to achieve an active material composite A-2.
[00109] The active material composite A-2 was then mixed with PTFE fibrillating binder and calendered at a roller speed of 1 m/min, at 120?, for 120 seconds to obtain a cathode film CA-2.
[00110] The active material composite A-2 was characterized for analysing the physical and morphological properties.
Characterization of active material composite A-2
a. FESEM and XRD analysis
[00111] FESEM and XRD analysis of active material composite A-2 obtained by high shear mixing at 2500 rpm for 2 h is given in Figure 10 and Figure 11 respectively. The FESEM image of active material composite A-2 revealed indefinite and rough appearances on the surface which indicated non-uniform coating of LATP coating on the active material surface. Hence, it was implied that the particle size differences and variation in surface areas between NMC and conductive carbons (KB and KS6L) were not matching enough to result in a uniform coating of conductive carbon on the surface of NMC particles in active material composite A-2. Hence, it was confirmed that the process conditions for the preparation of A-1 was not appropriate for the preparation of A-2. The smoothness and uniformity of the coating in the active material composite A-2 was not as good as that of active material composite A-1.
[00112] The XRD pattern for active material composite A-2 exhibited a hexagonal crystal structure with a space group of R-3m. The visible peak splitting was observed at 38 and 65 degrees corresponding to the planes (006/012) and (018/110) of NMC respectively. Since the LATP and conductive carbon was a surface coating rather than doping, no extra peaks other than NMC peaks were present. The NMC peaks were observed at approximately 19°, 37°, 38°, 45°, 48°, 58°, 65°, and 68° values of 2?.

b. EDAX spectrum and elemental mapping
[00113] This non-uniformity in carbon coating over NMC was confirmed by the increase in the signal intensity value in EDAX spectrum given in Figure 12. The signal intensity value increased for only certain elements due to high coating thickness or higher concentration of elements in certain areas. The clusters appeared in the elemental mapping analysis (Figure 13) also indicated the non-uniform coating or varying thickness of the coating material. Further, it was also observed that the active material composite did not show desirable uniformity and homogeneity in electrode morphology when the carbon was added in the first step, as in the case if active material composite A-2.

EXAMPLE 3
Preparation of the active material composite A-3 (NMC coated with a layer of LATP and conductive carbon is dispersed in the layer of LATP)
[00114] For the comparative purposes of the present disclosure, an active material composite A-3 and a cathode film CA-3 were prepared by the below process.
[00115] An active material composite A-3 was prepared by coating the active material NMC with a layer of LATP comprising 1% by weight of conductive carbon (0.6% (w/w) of KB and 0.4% (w/w) of KS6L) dispersed in LATP. The conductive carbons were dispersed in LATP via blending to obtain modified LATP. The modified LATP was then coated on the surface of NMC via high shear mixing with active material NMC at 3000 rpm for 2 hours followed by calcining at 300 ? for 4 hours in an oxygen atmosphere to achieve an active material composite A-3.
[00116] The active material composite A-3 was then mixed with PTFE fibrillating binder and calendered at a roller speed of 1m/min, at 120?, for 120 seconds to obtain a cathode film CA-3.

EXAMPLE 4
Analysis of parameters affecting uniform coating of protective material on active material.
[00117] In the preceding examples 1, 2 and 3, it was observed that coating of conductive carbon in the second step and high shear mixing at 3500 rpm for 4h resulted in improved homogeneity and uniformity of LATP coating and conductive carbon coating. The other process parameters which can affect the uniform coating over NMC was studied in this example.
a. Calcination
[00118] A LATP coating upon NMC surface was done by blending using a mini mixer at 2500 rpm for 2 h. After the LATP and NMC blending, calcination was done at 300 °C for 4 h in O2 atmosphere. The calcination process facilitated in roughening and thereby increased the NMC surface area, which ensured proper physical adhesion of LATP over the NMC surface. Additionally, when the calcination process was carried out at a temperature higher than 900 ?, it resulted in phase transformations of the active material.
b. Weight percentage of protective material (LATP) and high shear mixing parameters
[00119] Two active material composites were prepared with 1.5 and 2 wt% LATP as per the process given in Example 1, with varied blending parameters of 2500 rpm and 3000 rpm, for each of the composites. Further, corresponding cathode films were prepared using the prepared active material composites. The electrochemical analysis of all the prepared cathodes were carried out using wet electrode validation and the details are provided in Table 1. Observations are given in Figure 14, wherein C 2wt% and D 2wt% refer to charging and discharging cycles of cathode film comprising 2 wt% of LATP; and C 1.5wt% and D 1.5wt% refer to charging and discharging cycles of cathode film comprising 1.5 wt% of LATP.
Table 1
RPM LATP wt% 1st charge
(mAh/g) 1st discharge
(mAh/g) 2nd charge
(mAh/g) 2nd discharge
(mAh/g) ICE
(%) Capacity retention
(50 cycles)
(%)
2500 1.5 238.2 212.1 213.3 212.3 90.5 93.3
2500 2 233.5 203.2 204 203.5 87 91.6
3000 1.5 235.8 208.8 209.8 208.9 88.5 94.82
3000 2 230.9 204.9 205.8 205.8 88.7 91.74

[00120] Among the cathode films, the cathode film comprising 1.5 wt% of LATP coated upon active material NMC prepared by high shear mixing at 2500 rpm showed better electrochemical performance by retaining 93.3% capacity of electrode after 50 cycles and achieve better ICE value of 90.5%, compared to the other cathode films comprising 2 wt % of LATP coated upon active material NMC prepared by high shear mixing at 2500 rpm and 3000 rpm, which retained 91.6% capacity and 91.74% capacity respectively, after 50 cycles (Figure 14).
[00121] In addition, the cathode film comprising 1.5 wt% of LATP obtained by high shear mixing at 3000 rpm showed a capacity retention 94.82% after 50 cycles. However, the ICE obtained for this cathode film was less than that of the cathode film comprising 1.5 wt% of LATP obtained by high shear mixing at 2500 rpm. Hence 1.5 wt% of LATP was found to be optimum amount for LATP coating and 2500 rpm was found to be the optimum high shear mixing speed for uniformly and homogenously coating of LATP on the NMC surface and consequently resulting in better electrochemical performance.
b. Weight percentage of conductive carbon
[00122] Conductive carbon was coated over NMC coated with LATP, by high shear mixing at 3500-4000 rpm for 4 h using the mini mixer. The conductive carbon used for coating was a mixture of KB and K6SL. The carbon coating optimization was carried out using 0.9 wt% (0.6 % KB and 0.3% K6SL) and 1 wt% carbon (0.6% KB and 0.4% K6SL). The surface area was estimated to be 1330 m2/g for KB and 18.8 m2/g for K6SL. The particle size of K6SL was ~4.2 µm and that of KB was ~39 µm. In active material composite comprising 1 wt% of conductive carbon, excess of graphitic carbon was found as flakes throughout the composite, as shown in the FESEM image depicted in Figure 5C. Hence, 0.9 wt % was found to be desirable for achieving a composite with uniform carbon coating over the LATP coated NMC surface.

EXAMPLE 5
Electrochemical analysis
[00123] To study the electrochemical performance of the active material, dry electrode and wet electrode validation was carried out for the cathode films prepared by the process as explained in Examples 1 and 2. For wet electrode validation, a slurry was prepared by mixing the active material composite with a binder in the presence of a solvent N-methyl pyrrolidone (NMP) followed by coating the slurry over an aluminium current collector and drying under vacuum to obtain a cathode. It was cut into circular disc using which coin cells were fabricated for the analysis.
[00124] For dry electrode validation, the active material composite was mixed with a fibrillating binder and pressed over an aluminium current collector using a hot roll calendering machine to obtain a cathode. The cathode was then cut into circular disc which was assembled with a separator, an anode, and other components into a coin cell inside the glove box. The liquid electrolyte used in both the validation techniques were 1M LiPF6 dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) solvent.
a. Wet electrode validation of cathode film CA-1
[00125] The wet electrode validation was performed for the cathode film CA-1 and the observations are given in Figure 15 (a) wherein C_1 refers to first charging, D_1 refers to first discharging, C_2 refers to second charging, D_2 refers to second discharging C_3 refers to third charging, D_3 refers to third discharging and (b) wherein C refers to charge capacity, D refers to discharge capacity and CE refers to coulombic efficiency. The cathode film CA-1 delivered a specific capacitance of 206 mAh g-1 with ICE of 90.5%. In the second cycle, the discharge capacity was found to be 206.5 mAh g-1 with 99.6% Coulombic efficiency. In the third cycle, the cathode film CA-1 delivered 206.2 mAh g-1 capacity with 99.7% Coulombic efficiency. Figure 15 (b) shows the capacity retention with coulombic efficiency data for cathode film CA-1. The cycle test for 50 cycles at 25 °C was analysed for cathode film CA-1, to observe a capacity retention of 93.3%.
b. Wet electrode validation for cathode film comprising pristine NMC in comparison with cathode film CA-1.
[00126] The wet electrode validation was performed for the cathode film comprising 97.5% by weight of pristine NMC and 2.5% of PVDF in comparison with a cathode comprising 97.5% by weight of modified active material M-1 and 2.5% of PVDF. The observations for pristine NMC and modified active material M-1 are provided in Figure 16 (a) and (b), respectively. In Figure 16 (a) and (b), C_1 refers to first charging, D_1 refers to first discharging, C_2 refers to second charging, D_2 refers to second discharging C_3 refers to third charging, D_3 refers to third discharging. The wet electrode validation performed for the cathode comprising pristine NMC as active material delivered a specific capacitance of 198.6 mAh g-1 with ICE of 88.4%. In the second cycle, the discharge capacity was 198.2 mAh g-1 with 99.4% Coulombic efficiency. In third cycle, the discharge capacity was 197.7 mAh g-1 with 99% Coulombic efficiency.
[00127] The wet electrode validation performed for the cathode comprising M-1 as the active material delivered a specific capacitance of 212.1 mAh g-1 with ICE of 90.5%. In the second cycle, the discharge capacity was 212.2 mAh g-1 with 99.5% Coulombic efficiency. In third cycle, the discharge capacity was 212 with 99.4% Coulombic efficiency. Hence, it was concluded that the LATP coating upon the surface of active material NMC is technically advantageous over the cathode comprising pristine NMC as active material.
c. Dry electrode validation of cathode film CA-1
[00128] The dry electrode validation was performed for the cathode film CA-1 that delivered a specific capacitance of 194.3 mAh g-1 with ICE of 94.7%. In the second cycle, the discharge capacity was found to be 194.2 mAh g-1 with 99.7% Coulombic efficiency. The third cycle delivers a discharge capacity of 193.7 mAh g-1 with Coulombic efficiency of 99.4%. The observations are depicted in Figure 17, wherein C_1 refers to first charging, D_1 refers to first discharging, C_2 refers to second charging, D_2 refers to second discharging C_3 refers to third charging, D_3 refers to third discharging.
[00129] Hence, it was inferred that the cathode film CA-1 comprising the active material composite (A-1) showed an enhanced electrochemical performance in dry electrode validation.
d. Electrochemical impedance spectroscopic studies
[00130] The electrochemical impedance of modified active material (M-1) and active material composite (A-1) against the lithium phosphorous chloride (LPSCl) electrolyte was evaluated for 52 h at room temperature and 60 ?. The observations for electrochemical impedance showing reactivity of modified active material M-1 with LPSCl electrolyte at room temperature and at 60 ? are depicted in Figure 18 (a) and (b) respectively.
[00131] From the EIS curve at room temperature the resistance was 15.2k ohm, which was stable over a longer period of time (52h) during the aging studies. This revealed that the LPSCl was stable with the modified active material M-1, at room temperature. At 60 ?, the resistance was found to be 143.2 Ohm. Here, the ionic conductivity increased at higher temperature which resulted in reduced impedance of the modified active material M-1. All the curves overlapped with each other, and it was stable with LPSCl after 52 h.
[00132] The observations for electrochemical impedance showing reactivity of active material composite A-1 with LPSCl electrolyte at 60? is depicted in Figure 18 (c). From the figures, it was evident that the active material composite A-1 exhibited stable electrochemical performance during the reactivity studies when compared to the bare NMC or modified active material at room temperature and at 60?. The active material composite-1 showed a resistance of about 149 Ohms. Stable performance depicted that, as the NMC was very sensitive to the exposure with the LPSCl, coating of the layer of LATP followed by the layer of the conductive carbons upon NMC surface prevented the NMC structural decomposition when it was exposed to LPSCl.
[00133] The resistance of active material composite A-3 was analysed using the time dependent electrochemical impedance spectroscopic (EIS) studies of the active material composite A-3. Results are shown in Figure 18 (d), where the high charge transfer resistance and the growing impedance over the time have been observed. The A-3 showed a resistance of 1282 Ohms at room temperature. However, the EIS analysis of active material composite A-1 against lithium phosphorous chloride (LPSCl) electrolyte at room temperature showed a resistance of 149 Ohms only.
[00134] Hence, the sequential coating of LATP followed by the carbon over the NMC conferred as a prominent solution towards the stability of the cathode active material when exposed to a sulfide based solid electrolyte in terms of electrochemical performance as well as the lower internal resistance of the cathode.
[00135] Moreover, internal resistance of the cathode was the primary factor to attain the better electrochemical performances. The sequential coating of LATP layer on top of NMC surface and then coating a layer of the conductive carbon KB and KS6L on top of the layer of LATP gave positively reduced resistance results which are provided in Figure 18 (b). In the EIS analysis for active material composite A-1, the 52-h time-dependent EIS of NMC/LATP/C showed stable performance during the reactivity studies at 60?, indicating low charge transfer resistance without any impedance growth over the time.

ADVANTAGES OF THE PRESENT INVENTION
[00136] The present disclosure provides an active material composite comprising: an active material coated with a layer of protective material and a layer of conductive carbon, wherein the layer of protective material is disposed between the layer of the conductive carbon and the active material surface. This dual layer coating upon the active material surface acts as a protective coating, by virtue of which the reactivity of the active material with sulfur-based electrolytes is reduced significantly. This reduction in reactivity results in prevention of decomposition of the active material with sulfur-based electrolytes consequently resulting in better electrochemical performance with appreciable cycle life and reduced resistance. The present disclosure also provides an order of coating the layers, which includes coating the layer of LATP in the first step, followed by the layer of conductive carbon. The conductive carbon coating was achieved only after the coating of LATP. The modified active material obtained during the process comprising an active material (NMC) coated with a protective material (LATP) exhibits a rough surface that provides binding sites for the conductive carbon on the modified active material surface. Addition of conductive carbon in the disclosed weight ranges and disclosed processes also improved the dry film formation and exhibited an increased tensile strength value. The present disclosure provides a solution for the problem of active material surface reactivity based on a tri-layer system that reduced reactivity with sulfide electrolyte and improved catholyte dry film with desired thickness, porosity, density, and tensile strength. Another major advantage of the disclosed active material composite is that it can be directly used as a catholyte without any further addition of solid electrolyte. This active material composite is ideally suited for all solid-state battery applications rather than for semi-solid/wet coated electrodes for solid-state battery applications.
, Claims:I/We Claim:

1. An active material composite comprising:
a. an active material;
b. a protective material; and
c. a conductive carbon,
wherein the active material is coated with a layer of the protective material and a layer of the conductive carbon;
wherein the layer of the protective material is disposed between the active material and the layer of the conductive carbon;
wherein the layer of the protective material has a thickness in a range of 100 to 170 nm; and
wherein the layer of the conductive carbon has a thickness in a range of 5 to 30 nm.
2. The active material composite as claimed in claim 1, wherein the active material is in a weight range of 96.5 to 98.5% (w/w); and is selected from lithium nickel manganese cobalt (NMC), lithium nickel-cobalt-aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium rich manganese rich oxide (LRMR), lithium manganese oxide (LMO) or combinations thereof.
3. The active material composite as claimed in claim 1, wherein the active material has a particle size in a range of 4 to 15 µm; and the protective material has a particle size in a range of 120 to 200 nm and ionic conductivity in a range of 1 × 10-4 to 2 × 10-4 S/cm.
4. The active material composite as claimed in claim 1, wherein the protective material is in a weight range of 1 to 2% (w/w); and is selected from lithium aluminium titanium phosphate (LATP), aluminium phosphate, iron phosphate, or combinations thereof.
5. The active material composite as claimed in claim 1, wherein the conductive carbon is in a weight range of 0.5 to 1.5% (w/w); and is selected from, carbon black, graphite, activated carbon, singled walled carbon nanotube, multi-walled carbon nanotube, graphene, or combinations thereof.
6. An electrode film comprising 97 to 98% (w/w) of the active material composite as claimed in claim 1, and 2 to 3% (w/w) of a fibrillating binder.
7. The electrode film as claimed in claim 6, wherein the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene polymer (FEP), fluoroethylene vinyl ether (FEVE), or combinations thereof.
8. The electrode film as claimed in claim 6, wherein the electrode film has a thickness in a range of 50 to 100µm; and a porosity in a range of 0 to 2%.
9. The electrode film as claimed in claim 6, wherein the electrode film exhibits a tensile strength in a range of 300 to 350 kgf/cm²; and a resistance in a range of 120 to 150 Ohms.
10. The electrode film as claimed in claim 6, wherein the electrode film exhibits a specific capacity in a range of 193 to 210 mAh/g; and an initial coulombic efficiency in a range of 90 to 95%.
11. The electrode film as claimed in claim 6, wherein the electrode film exhibits a capacity retention in a range of 93 to 99% up to 50 cycles at 25?.
12. A process for preparing the active material composite as claimed in claim 1, the process comprising:
a. blending an active material with a protective material followed by calcination to obtain a modified active material; and
b. high shear mixing the modified active material with a conductive carbon to obtain the active material composite.
13. The process as claimed in claim 12, wherein the blending is carried out at a speed in a range of 2000 to 3500 rpm for a period in a range of 1.5 to 2.5 hours.
14. The process as claimed in claim 12, wherein the calcination is carried out at a temperature in a range of 200 to 400 ?, for a period in a range of 3 to 5 hours.
15. The process as claimed in claim 12, wherein the high shear mixing is carried out at a speed in a range of 3500 to 4000 rpm for a period in a range of 3 to 5 hours.
16. The process as claimed in claim 12, wherein the process further comprises mixing a fibrillating binder with the active material composite followed by calendering to obtain an electrode film.
17. The process as claimed in claim 16, wherein mixing is carried out at a speed in a range of 1500 to 3000 rpm and at a temperature in a range of 15 to 80 ?.
18. The process as claimed in claim 16, wherein calendering is carried out at a roller speed in a range of 0.5 to 2 m/min at a temperature in a range of 100 to 150 ?, and for a period in a range of 30 to 200 seconds.
19. An electrochemical cell comprising:
a. a cathode comprising the electrode film as claimed in claim 6;
b. an anode; and
c. an electrolyte.