DESC:FIELD OF INVENTION
[0001] The present disclosure broadly relates to the field of battery. Particularly, the present disclosure relates to electrode materials, more particularly to electrode composite having cathode active material, and processes thereof.

BACKGROUND OF THE INVENTION
[0002] In the current state of LIBs, dry coating technology gained prior attention compared with traditional wet slurry process. Binder fibrillation is a key parameter that fixes the dry coating electrode in a flexible texture. The active material, conductive additive and binder need to be mixed homogeneously to achieve the flexible free-standing film. The shearing force makes the binder into fibrils, which forms a matrix to blend and support electrode powder together. The process that the binder forms the fibrils under shearing force is called binder fibrillation. Accounting for the high energy density of Ni based cathode materials, huge interest is shed on this class of materials, especially in EV applications. Ni-rich cathode materials have become one of the most promising cathode materials for advanced high-energy Li-ion batteries (LIBs) owing to their high specific capacity.
[0003] For the aforementioned class of cathode materials, free Li ions as well as the Li residues present on the cathode material surface impacts immense reverse effect in the electrochemical properties of the material with retardation of capacity and cycle life. Also, it creates the formation of thick dead layers on the electrode- electrolyte interface due to the unwanted side reactions with the electrolyte that leads to increased impedance. Ni-rich cathode materials which are sensitive to traces of moisture and CO2 in the air, tend to react with them to produce LiOH and Li2CO3 at the particle surface region named residual lithium compounds. The residual lithium compounds deteriorate the comprehensive performances of Ni-rich cathode materials. These residues cause low initial coulombic efficiency and poor storage property, bringing about potential safety hazards, and gelatinizing the electrode slurry. Therefore, it is of considerable significance to remove the residual lithium compounds.
[0004] Accounting for the dry electrode process, in the present scenario, a composite of PTFE and PVDF is used along with the cathode and conductive agent. PVDF binds the material together with its adhesion property and PTFE enhances the fibrillation process when shear force is applied onto the material. Though this combination does the fibrillation and adhesion of the material on the current collector, it lacks the ability to protect the cathode material surface during electrochemistry. Moreover, electrochemically inactive materials like binders reduce the energy density of electrode materials. Researchers adopt several technologies such as surface coating, elemental doping etc., to protect the active material as a separate process apart from electrode process. Hence, there is unmet need in the art to develop a binder material which protects the electrode and does not diminish the performance of the cell.

BRIEF DESCRIPTION OF THE FIGURES
[0005] 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.
[0006] Figure 1 depicts the general schematic representation of the preparation of the electrode composite, in accordance with an embodiment of the present disclosure.
[0007] Figure 2 depicts the mechanism of formation of CEI layer between the cathode and electrolyte, in accordance with an embodiment of the present disclosure.
[0008] Figure 3 depicts the specific charge-discharge capacities of the dry cathodes fabricated with and without PDDA binder.
[0009] Figure 4 depicts the Raman spectrum analysis of the cathode after the first charge-discharge cycle, in accordance with an embodiment of the present disclosure

DETAILED DESCRIPTION OF THE INVENTION
[0010] 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
[0011] 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.
[0012] 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.
[0013] 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”.
[0014] 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 element or steps but not the exclusion of any other element or step or group of element or steps.
[0015] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.
[0016] The term “w/w” means the percentage by weight, relative to the weight of the total composition, unless otherwise specified.
[0017] The term "at least one" is used to mean one or more and thus includes individual components as well as mixtures/combinations.
[0018] The term “active material” refers to the active constituent of an electrode, which comprises the particles that undergo oxidation or reduction, resulting in electroconductivity. Examples of active material in the present disclosure include but not limited to layered lithium nickel manganese cobalt oxide (LiaNixMnyCozMbO2), spinel lithium nickel manganese oxide (LiNiMnMbO4), or combinations thereof, wherein M= Fe, Mn, Ni, Co, Cr, Al, Ti, Zr, W, Mo, Ru, V, Y, Nb; a=0.9 to 1.3; b=0.01 to 0.5; x=0.1 to 0.9; y=0.01 to 0.7; and z= 0.01 to 0.5.
[0019] The term “conductive carbon” refers to an electrically conductive allotrope of carbon that provide channel for electronic movement, resulting in higher discharge capacity and better cycling performance. Examples of conductive carbon include but are not limited to super P, carbon nanotubes, graphite, graphene, ketjen black, carbon black, or carbon fibers.
[0020] The term “binder” refers to the substance that provides adhesion and mechanical integrity, to the active material. In the present disclosure, binder is selected from a fibrillating binder, a polyelectrolyte binder, or combinations thereof.
[0021] The term "fibrillation" refers to the formation of a lace-like configuration of minute fibers called "fibrils" upon exposure to heat, shear, and/or other pressure. Such fibrils are easily formed when a fibrillating polymer is mixed, stirred, extruded, compressed, or the like.
[0022] The term “fibrillating binder” refers to a type of a binder, which has the property to form small fibrils under the application of shear force. The fibrillating binder provides mechanical integrity to the electrode during manufacturing and provide optimal dispersion and adhesion of the active material and conductive additive. Examples of fibrillating binder in the present disclosure includes but not limited to polytetrafluoroethylene (PTFE).
[0023] Examples of polyelectrolyte binder include but not limited to poly diallyl dimethyl ammonium chloride (PDDA), 2,2'-azobis(2- amidinopropane)dihydrochloride (AAPH), 2-(methacryloxy)-ethyltrimethyl ammonium chloride (MAETAC), 3-(methacrylamido)propyl trimethyl ammonium chloride (MAPTAC) or combinations thereof.
[0024] 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. For example, temperature in the range of 80 to 120 ? should be interpreted to include not only the explicitly recited limits of 80 to 120 ? but also to include sub-ranges, such as 85 to 100 ?, 97 to 119 ? and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 81.5 ?, 100 ? and 119.9?.
[0025] 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
[0026] 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
[0027] As discussed in the background, there is a dire need in the art to develop a useful strategy to mitigate the problem of residual lithium upon the cathode material. Ni-rich cathode materials are sensitive and tend to react with moisture and air to generate residual lithium compounds. The residual lithium compounds deteriorate the performances of Ni-rich cathode materials and cause low initial coulombic efficiency with poor storage property, leading to potential safety hazards. Therefore, to remove the residual lithium compounds various strategies have been adopted such as incorporation of additives in electrolytes and electrodes. However, these additives lead to the formation of pre-SEI (solid electrolyte interface) layer which deteriorates the performance of the cell. Another technique to be adopted is bringing modification in the electrodes such that there occurs an electrode-electrolyte interface using the residual lithium which stabilizes the interface. Accordingly, in the present disclosure, polyelectrolytes such as poly diallyl dimethyl ammonium chloride (PDDA) which acts as a binder and as a growth initiator for the cathode-electrolyte interface (CEI) is used along with a fibrillating binder polytetrafluoroethylene (PTFE) in combination with NMC based cathode active material and conducting additives to obtain an electrode composite.
[0028] Further, a cationic polyelectrolyte capable of forming a thin CEI (cathode electrolyte interface) layer on the cathode surface is used to protect the cathode material from unwanted side reactions during further electrochemical reactions. The free Cl- ions in the PDDA interact with the Li ion residues to form a LiCl layer (or CEI) resulting in the improved efficiency of the battery system. The CEI layer will enhance the material structural stability. Presence of the in-situ formed CEI layer eliminates or minimizes the usage of any additional electrolyte additive that could serve the working of the cathode material even at high voltages and elevated temperatures with a protected surface.
[0029] In an embodiment of the present disclosure, there is provided an electrode composite comprising: (a) an active material; (b) a conductive carbon; (c) at least one fibrillating binder; and (d) at least one non-fibrillating binder, wherein the at least one non fibrillating binder is a polyelectrolyte binder.
[0030] In an embodiment of the present disclosure, there is provided an electrode composite as disclosed herein, wherein the active material is in a weight range of 96 to 99 % with respect to total weight of the composite; and the conductive carbon is in a weight range of 0.5 to 1.5 % with respect to total weight of the composite. In another embodiment of the present disclosure, the active material is in a weight range of 97 to 98 % with respect to total weight of the composite; and the conductive carbon is in a weight range of 0.8 to 1.2 % with respect to total weight of the composite. In yet another embodiment of the present disclosure, the active material is in a weight of 97.5 % with respect to total weight of the composite; and the conductive carbon is in a weight of 1 % with respect to total weight of the composite.
[0031] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the fibrillating binder and the non-fibrillating binder are in a weight ratio range of 9.8:0.2 to 8:2. In another embodiment of the present disclosure, the fibrillating binder and the non-fibrillating binder are in a weight ratio range of 9.5:0.5 to 8.5:1.5. In yet another embodiment of the present disclosure, the fibrillating binder and the non-fibrillating binder are in a weight ratio of 9:1.
[0032] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the fibrillating binder is in a weight range of 0.5 to 2.8 % with respect to total weight of the composite. In another embodiment of the present disclosure, the fibrillating binder is in a weight range of 1 to 2 % with respect to total weight of the composite. In yet another embodiment of the present disclosure, the fibrillating binder is in a weight of 1.3 % with respect to total weight of the composite.
[0033] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the polyelectrolyte binder is in a weight range of 0.02 to 0.25 % with respect to total weight of the composite. In another embodiment of the present disclosure, the polyelectrolyte binder is in a weight range of 0.1 to 0.2 % with respect to total weight of the composite. In yet another embodiment of the present disclosure, the polyelectrolyte binder is in a weight of 0.2 % with respect to total weight of the composite.
[0034] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the total weight of the fibrillating binder and the non- fibrillating binder is up to 3 % with respect to total weight of the composite. In another embodiment of the present disclosure, the total weight of the fibrillating binder and the non-fibrillating binder is 1.5 % with respect to total weight of the composite.
[0035] In an embodiment of the present disclosure, there is provided an electrode composite comprising: (a) an active material in a weight range of 96 to 99 % with respect to total weight of the composite; (b) a conductive carbon in a weight range of 0.5 to 1.5 % with respect to total weight of the composite; (c) at least one fibrillating binder in a weight range of 1 to 2 % with respect to total weight of the composite; and (d) at least one non-fibrillating binder in a weight range of 0.02 to 0.25 % with respect to total weight of the composite, wherein the at least one non fibrillating binder is a polyelectrolyte binder.
[0036] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the active material is selected from layered lithium nickel manganese cobalt oxide (LiaNixMnyCozMbO2), spinel lithium nickel manganese oxide (LiNiMnMbO4), or combinations thereof, wherein M= Fe, Mn, Ni, Co, Cr, Al, Ti, Zr, W, Mo, Ru, V, Y, Nb, or combination thereof, a=0.9 to 1.3, b=0.01 to 0.5, x=0.1 to 0.9, y=0.01 to 0.7, and z= 0.01 to 0.5. In another embodiment of the present disclosure, the active material is LiNi0.8Mn0.1Co0.1O2.
[0037] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the conductive carbon is selected from super p, carbon nanotubes, graphite, graphene, ketjen black, carbon black, carbon fibers or combinations thereof. In an embodiment of the present disclosure, the conductive carbon is super p.
[0038] In an embodiment of the present disclosure, there is provided a composite as disclosed herein, wherein the fibrillating binder is polytetrafluro ethylene (PTFE)
[0039] In an embodiment of the present disclosure, there is provided an electrode composite as disclosed herein, wherein the polyelectrolyte binder is selected from poly diallyl dimethyl ammonium chloride (PDDA), 2,2'-azobis(2- amidinopropane)dihydrochloride (AAPH), 2-(methacryloxy)-ethyltrimethyl ammonium chloride (MAETAC), 3-(methacrylamido)propyl trimethyl ammonium chloride (MAPTAC), or combinations thereof. In another embodiment of the present disclosure, the polyelectrolyte binder is poly diallyl dimethyl ammonium chloride (PDDA).
[0040] In an embodiment of the present disclosure, there is provided an electrode comprising the electrode composite as disclosed herein with a current collector.
[0041] In an embodiment of the present disclosure, there is provided an electrode comprising: the electrode composite having (a) an active material; (b) a conductive carbon; (c) at least one fibrillating binder; and (d) at least one non- fibrillating binder, wherein the at least one non fibrillating binder is a polyelectrolyte binder; and a carbon or polymer pre-coated aluminium foil as current collector.
[0042] In an embodiment of the present disclosure, there is provided a process of preparation of the electrode composite as disclosed herein, the process comprising:
a. subjecting an active material to shear mixing at a temperature in a range of 15 to 30 oC, and at a speed in a range of 1000 to 3000 rpm with a conductive carbon to obtain a first mixture;
b. adding a non-fibrillating binder to the first mixture followed by shearing to obtain a second mixture;
c. adding a fibrillating binder to the second mixture followed by shearing to obtain a third mixture; and
d. subjecting the third mixture to calendaring at 70 to 150 oC and 50 to 150 bar pressure to obtain the composite.
[0043] In an embodiment of the present disclosure, there is provided a process of preparation of the electrode composite as disclosed herein, the process comprising:
a. subjecting an active material to shear mixing at a temperature in a range of 15 to 30 oC, and at a speed in a range of 1000 to 3000 rpm with a conductive carbon to obtain a first mixture;
b. adding a non-fibrillating binder to the first mixture followed by shearing to obtain a second mixture;
c. adding a fibrillating binder to the second mixture followed by shearing to obtain a third mixture; and
d. the third mixture is further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed in a range of 2000 to 4000 rpm; and calendaring at 70 to 150 oC and 50 to 150 bar pressure to obtain the composite.
[0044] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the non-fibrillating binder in the third mixture is a polyelectrolyte binder.
[0045] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein adding the non-fibrillating binder to the first mixture followed by shearing is carried out at a temperature in a range of 15 to 30 oC. In another embodiment of the present disclosure, the non-fibrillating binder to the first mixture followed by shearing is carried out at a temperature in a range of around 20 to 27 oC. In yet another embodiment of the present disclosure, the non- fibrillating binder to the first mixture followed by shearing is carried out at a temperature of around 25 oC.
[0046] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein adding the fibrillating binder to the second mixture is further subjected to shear mixing at a temperature in a range of 15 to 30 oC. In another embodiment of the present disclosure, the fibrillating binder to the second is further subjected to shear mixing at a temperature in a range of around 20 to 27 oC. In yet another embodiment of the present disclosure, the fibrillating binder to the second is further subjected to shear mixing at a temperature in a range of around 25 oC.
[0047] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the third mixture is further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed in a range of 2000 to 4000 rpm, prior to calendaring. In another embodiment of the present disclosure, the third mixture is further subjected to high shear mixing at a temperature in a range of 70 to 90 oC, and at a speed in a range of 2500 to 3500 rpm, prior to calendering. In yet another embodiment of the present disclosure, the third mixture is further subjected to high shear mixing at a temperature in a range of around 80 oC, and at a speed in a range of around 3000 rpm, prior to calendaring.
[0048] In an embodiment of the present disclosure, there is provided a process as disclosed herein, wherein the composite is cooled to a temperature in a range of 15 to 20 oC, under stirring at a speed in a range of 300 to 600 rpm. In another embodiment of the present disclosure, the composite is cooled to a temperature in a range of around 18 oC, under stirring at a speed in a range of around 500 rpm.
[0049] In an embodiment of the present disclosure, there is provided a process of preparation of the electrode composite as disclosed herein, the process comprising:
a. subjecting an active material to shear mixing at a temperature in a range of 15 to 30 oC, and at a speed in a range of 1000 to 3000 rpm with a conductive carbon to obtain a first mixture;
b. adding a non-fibrillating binder to the first mixture followed by shearing at a temperature in a range of 15 to 30 oC to obtain a second mixture;
c. adding a fibrillating binder to the second mixture followed by shearing at a temperature in a range of 15 to 30 oC to obtain a third mixture;
d. the third mixture is further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed in a range of 2000 to 4000 rpm; calendaring at 70 to 150 oC and 50 to 150 bar pressure to obtain the composite.
[0050] In an embodiment of the present disclosure, there is provided a process of preparation of the electrode composite as disclosed herein, the process comprising:
a. subjecting an active material to shear mixing at a temperature in a range of 15 to 30 oC, and at a speed in a range of 1000 to 3000 rpm with a conductive carbon to obtain a first mixture;
b. adding a non-fibrillating binder to the first mixture followed by shearing to obtain a second mixture;
c. adding a fibrillating binder to the second mixture followed by shearing to obtain a third mixture;
d. the third mixture is further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed in a range of 2000 to 4000 rpm;
e. subjecting the third mixture to calendaring at 70 to 150 oC and 50 to 150 bar pressure to obtain the composite; and
f. the composite is cooled to a temperature in a range of 15 to 20 oC, under stirring at a speed in a range of 300 to 600 rpm. In another embodiment of the present disclosure, the composite is cooled to a temperature in a range of around 18 oC, under stirring at a speed in a range of around 500 rpm.
[0051] In an embodiment of the present disclosure, there is provided an electrochemical cell comprising:
(a) a cathode comprising the composite with a current collector, said composite having:
(i) an active material; (ii) a conductive carbon; (iii) at least one fibrillating binder and (iv) at least one non-fibrillating binder, wherein the at least one non- fibrillating binder is a polyelectrolyte binder;
(b) an anode; and
(c) an electrolyte.

[0052] The disclosure will now be illustrated with working 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.

Materials and Methods
[0053] The various chemicals and solvents used in the present disclosure are as follows:
LiNi0.8Mn0.1Co0.1O2, Super P, Poly diallyl dimethyl ammonium chloride (PDDA), polytetrafluoroethylene (PTFE), carbon or polymer pre-coated aluminium foil, graphite-based anode, 1M LiPF6 dissolved in carbonate solvent electrolyte.
EXAMPLE 1
Preparation of Cathode Composite
[0054] 97.5 % by weight of LiNi0.8Mn0.1Co0.1O2 [active material] was subjected to shear mixing at a temperature of about 25 oC, and at a speed in a range of 1000 to 3000 rpm with 1 % by weight of super p (conductive carbon) to obtain a first mixture. 0.2 % by weight of poly diallyl dimethyl ammonium chloride (PDDA) [non-fibrillating polyelectrolyte binder] was added to the first mixture followed by shearing at a temperature of about 25 oC to obtain a second mixture. 1.3 % by weight of polytetrafluoroethylene (PTFE) [fibrillating binder] was added to the second mixture followed by shearing at a temperature in the range of 15 to 30 oC to obtain a third mixture. The third mixture was further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed of 3000 rpm. The third mixture was then subjected to calendaring at a temperature in the range of 70 to 150 oC and 50 to 150 bar pressure to obtain the composite. The composite was then cooled to a temperature in the range of 15 to 20 oC, under stirring at a speed in a range of 300 to 600 rpm. The schematic representation of the preparation of the composite is shown in figure 1.
EXAMPLE 2
Preparation of the cathode
[0055] This example illustrates the method of fabricating an electrode comprising the electrode composite as prepared in Example 1 of the present disclosure.
The electrode composite from Example 1 was uniformly dispersed on a current collector, wherein, the current collector is selected from carbon or polymer pre-coated aluminium foil, which is electrochemically neutral at the electrode operating voltages. The electrode composite prepared by the method as described in example 1 was laminated over a primer coated aluminium foil.
EXAMPLE 3
Preparation of the cathode
This example illustrates preparation of an electrochemical cell comprising the electrode as prepared in Example 2 of the present disclosure.
[0056] The electrochemical cell setup was obtained by assembling the sequentially stacked pellets of cathode prepared by the method as explained in example 2, and an anode on either sides of an electrolyte.
[0057] An electrochemical cell specifically a battery, and more specifically, a lithium-ion battery was prepared. The lithium-ion battery includes an anode (negative electrode) selected from natural graphite, synthetic graphite, silicon graphite composite or combinations thereof, the cathode (positive electrode) obtained by the process as disclosed in example 2 disposed to face the anode, and an electrolyte of 1M LiPF6 dissolved in carbonate solvent with added additives, placed between cathode and anode. The electrochemical cell obtained from the process explained above was analyzed for its battery performance, and capacity.
[0058] The polyelectrolyte PDDA in the cathode composite forms a cathode electrolyte interface (CEI) layer upon interaction with the residual lithium as depicted in figure 2.

Characterization of the Electrode Film
[0059] Raman Analysis: The cycled cathode was dismantled and characterized for the inspection of the CEI film. Figure 4 shows the Raman spectrum of electrode films comprising the PDDA. The Raman spectrum distinct peaks at 260 cm-1, 455 cm-1, 1320 cm-1, and 1550 cm-1, corresponding to vibrational modes associated with LiCl, LiF, COO, and CC, respectively. The peak observed at 260 cm-1, indicates of the formation of a LiCl layer on the cathode surface confirming the formation of LiCl at the electrode interface during the electrochemical processes.

Electrochemical Cell Performance
[0060] The electrochemical analysis was conducted using an electrode arrangement as described herein above, wherein the following electrolyte and solvent combinations were used. 1 M Lithium hexaflurophosphate, Ethylene carbonate, diethylene carbonate, dimethylene carbonate (Electrolyte 1); or 1.2 M Lithium hexaflurophosphate, Ethylene carbonate, diethylene carbonate, dimethylene carbonate (Electrolyte 2).
Observation and Results
[0061] Fig 3 depicts the Specific charge-discharge cycle data of the NMC-811 dry electrode with and without PDDA binder. The electrode with PDDA binder showed a discharge capacity of 216 mAh/g whereas the electrode without PDDA binder showed a discharge capacitiy of 212 mAh/g and the corresponding ICE values of 92.98% and 92.08%, respectively. These results supplement the fact that role of PDDA facilitates the formation of a stable CEI layer by reducing Li-residue content which in-turn enhances the ICE and discharge capacities of the Li-ion cell.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0062] The present disclosure provides an electrode composite comprising: (a) an active material; (b) a conductive carbon; and (c) at least one fibrillating binder; and (d) at least one non-fibrillating binder, wherein the at least one non-fibrillating binder is a polyelectrolyte binder. The cationic polyelectrolyte in the composite forms a thin layer similar to the cathode electrolyte interface (CEI) layer on the cathode surface protecting the electrode from unwanted side reactions during electrochemical cycles. The free chlorine ions of the polyelectrolyte react with the lithium residue present on the surface of cathode material resulting in a LiCl layer on the material surface thereby removing the excess free lithium from the electrode This LiCl layer enhances conductivity, improves electrode stability and thereby provide an improved the electrochemical performance of the cell.
,CLAIMS:I/We Claim:
1. An electrode composite comprising:
a. an active material;
b. a conductive carbon;
c. at least one fibrillating binder; and
d. at least one non-fibrillating binder,
wherein the at least one non fibrillating binder is a polyelectrolyte binder.
2. The composite as claimed in claim 1, wherein the active material is in a weight range of 96 to 99 % with respect to total weight of the composite; and the conductive carbon is in a weight range of 0.5 to 1.5 % with respect to total weight of the composite.
3. The composite as claimed in claim 1, wherein the fibrillating binder and the non-fibrillating binder are in a weight ratio range of 9.8:0.2 to 8:2.
4. The composite as claimed in claim 1, wherein the fibrillating binder is in a weight range of 0.5 to 2.8 % with respect to total weight of the composite.
5. The composite as claimed in claim 1, wherein the polyelectrolyte binder is in a weight range of 0.02 to 0.2 % with respect to total weight of the composite.
6. The composite as claimed in claim 1, wherein the active material is selected from layered lithium nickel manganese cobalt oxide (LiaNixMnyCozMbO2), spinel lithium nickel manganese oxide (LiNiMnMbO4), or combinations thereof, wherein M is independently selected from Fe, Mn, Ni, Co, Cr, Al, Ti, Zr, W, Mo, Ru, V, Y, Nb, or combinations thereof; a=0.9 to 1.3; b=0.01 to 0.5; x=0.1 to 0.9; y=0.01 to 0.7; and z= 0.01 to 0.5.
7. The composite as claimed in claim 1, wherein the conductive carbon is selected from super p, carbon nanotubes, graphite, graphene, ketjen black, carbon black, carbon fibers, or combinations thereof.
8. The composite as claimed in claim 1, wherein the fibrillating binder is polytetrafluro ethylene (PTFE).
9. The composite as claimed in claim 1, wherein the polyelectrolyte binder is selected from poly diallyl dimethyl ammonium chloride (PDDA), 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH), 2- (methacryloxy)-ethyltrimethyl ammonium chloride (MAETAC), 3- (methacrylamido)propyl trimethyl ammonium chloride (MAPTAC), or combinations thereof.
10. A process of preparation of the electrode composite as claimed in claim 1, the process comprising:
i. subjecting an active material to shear mixing at a temperature in a range of 15 to 30 oC, and at a speed in a range of 1000 to 3000 rpm with a conductive carbon to obtain a first mixture;
ii. adding a non-fibrillating binder to the first mixture followed by shearing to obtain a second mixture;
iii. adding a fibrillating binder to the second mixture followed by shearing to obtain a third mixture at a temperature range of 15 to 30 oC;
iv. the third mixture is further subjected to high shear mixing at a temperature in a range of 50 to 120 oC, and at a speed in a range of 2000 to 4000 rpm; and
v. subjecting the third mixture to calendaring at 70 to 150 oC and 50 to 150 bar pressure to obtain the composite; and
vi. cooling the composite to a temperature in a range of 15 to 20 ?, under stirring at a speed in a range of 300 to 600 rpm.