FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention: A PROCESS FOR PREPARING AN ELECTRODE, AND
IMPLEMENTATIONS THEREOF
2. Applicant(s)
NAME NATIONALITY ADDRESS
OLA ELECTRIC MOBILITY
LIMITED
Indian Regent Insignia, #414, 3rd Floor, 4th
Block, 17th Main, 100 Feet Road,
Koramangala, Bangalore, Karnataka
560034, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.
1
FIELD OF THE INVENTION
[0001] The present disclosure broadly relates to the field of batteries. Particularly,
the present disclosure relates to the process for fabricating the electrode, more
particularly the present disclosure relates to processes of preparing electrodes.
5 BACKGROUND OF THE INVENTION
[0002] The development of efficient fabrication techniques is of paramount
importance in the field of battery manufacture due to the increasing demand for
batteries worldwide. The major power source for electronics, automobiles, etc. is
secondary batteries. Hence, a substantial amount of research is underway to
10 enhance the energy density of existing secondary batteries at a reasonable cost by
improving several components of the secondary batteries.
[0003] Li-ion batteries, or lithium-ion batteries, are a type of secondary battery that
stores energy by means of the reversible intercalation of Li+
ions into electronically
conducting compounds. Li-ion batteries have higher specific energy, higher energy
15 density, better energy efficiency, longer cycle life, and longer calendar life in
comparison with conventional commercial rechargeable batteries.
[0004] The contact between the current collector and the composite film (which
comprises an active material, a conductive carbon, and a binder) serves as a gauge
for the mechanical integrity of the electrode material. Conductive additive although
20 being a minor component, is a crucial part of the Li-ion battery electrode and makes
up to a weight in a range of 1 to 5% of the total weight of the electrode. The adhesion
strength and electrochemical performance of the electrode are significantly
influenced by the particle size, structure, and aspect ratio of the conductive carbon
and active materials.
25 [0005] In addition, the mixing of the conductive carbon with the active material is
also challenging due to the agglomeration of the conductive carbon. Generally, the
conductive carbons that have been used for the electrode manufacture are graphite,
metal powder, metal fibres, and carbon nanomaterials. Based on their
morphological structure, conductive carbons (CC) are classified into two types: (a)
2
particle-like conductive carbons, such as graphite, Super P (SP), and Ketjen black
(KB), and (b) fiber-like conductive agents, such as carbon nanotubes (CNT), vaporgrown carbon fiber (VGCF), carbon nanofibers and metal fibers. Morphological
structures of conducting carbons affect conductivity and interactions between active
5 material and binder. Owing to high aspect ratio, excellent electrical and thermal
conductivity, and ease of preparation, carbon nanomaterials (such as carbon
nanotubes and carbon nanofibers) have been extensively used and preferred in Liion battery electrodes.
[0006] Due to the variations of particle size and difference in the aspect ratio
10 between the binder and carbon particles, agglomeration of carbon can easily occur
in the presence of the binder. Also, the improper distribution of the conducting
carbon in the electrodes may cause serious issues in terms of the dendritic growth
or short-circuiting during prolonged cycling. Therefore, the amount of carbon
particles having desirable morphology/aspect ratio is highly critical. Further, the
15 process for preparing is also crucial to avoid the improper distribution, and to attain
a homogenous mix and thereby reduce cell impedance and development of internal
resistance.
[0007] Thus, there is a dire need in the art to develop a cost-effective, efficient and
improved manufacturing process to develop electrode with high electrical
20 conductivity.
SUMMARY OF THE INVENTION
[0008] In a first aspect of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: a) mixing a primary conductive
carbon with a binder solution to obtain a pre-mixture; b) blending a first part of an
25 active material with the pre-mixture to obtain a blend; c) adding a first part of a
secondary conductive carbon to the blend and stirring to obtain a first mixture; d)
adding a second part of the active material with the first mixture to obtain a second
mixture; e) mixing a second part of the secondary conductive carbon with the
second mixture, followed by high-speed mixing to obtain an electrode slurry; and
3
f) processing of the electrode slurry to obtain the electrode, wherein the primary
conductive carbon and the secondary conductive carbon are in a weight ratio range
of 1:0.75 to 1:1.5, and wherein the combined weight of the primary conductive
carbon and the secondary conductive carbon is in a range of 1 to 2%, with respect
5 to the total weight of the electrode.
[0009] In a second aspect of the present disclosure, there is provided an electrode
obtained by the process as disclosed herein, wherein the electrode comprises: a) an
active material; b) a binder; c) a primary conductive carbon; and d) a secondary
conductive carbon, wherein the primary conductive carbon and the secondary
10 conductive carbon is present in a weight ratio range of 1: 0.75 to 1: 1.5.
[0010] In a third aspect of the present disclosure, there is provided an
electrochemical cell comprising: (a) an anode; (b) a cathode comprising the
electrode obtained by the process as disclosed herein; and (c) an electrolyte.
[0011] These and other features, aspects, and advantages of the present subject
15 matter will be better understood with reference to the following description and
appended claims. 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.
20 BRIEF DESCRIPTION OF THE FIGURES
[0012] 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.
25 [0013] Figure 1 depicts the field emission scanning electron microscopy (FESEM)
images of the (a) electrode EA prepared by the process 1; and (b) electrode CE-5
prepared by the comparative process 2, in accordance with an embodiment of the
present disclosure.
4
[0014] Figure 2 depicts the graphical representation of plane resistivity exhibited
by different electrodes, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Those skilled in the art will be aware that the present disclosure is subject
5 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.
10 Definitions
[0016] 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
15 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.
[0017] 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.
20 [0018] 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”.
[0019] Throughout this specification, unless the context requires otherwise the
word “comprise”, and variations such as “comprises” and “comprising”, will be
25 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.
[0020] The term “including” is used to mean “including but not limited to”.
“Including” and “including but not limited to” are used interchangeably.
5
[0021] The term “w/w” means the percentage by weight, relative to the weight of
the total composition, unless otherwise specified. The term "at least one" is used to
mean one or more and thus includes individual components as well as
mixtures/combinations.
5 [0022] 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 aspect of the present disclosure, the active material is
selected from lithium nickel manganese oxide (NMC), lithium cobalt oxide (LCO),
lithium manganese oxide (LMO), lithium iron phosphate (LFP), lithium yttrium
10 iron phosphate (LYP), lithium nickel manganese cobalt oxide, lithium nickel cobalt
aluminium oxide (NCA), lithium manganese phosphate (LiMnPO4), lithium cobalt
phosphate (LiCoPO4), lithium vanadium phosphate (LVP), spinel type alkali metal
transition metal oxides, alkali-transition metal oxides (AMO2) oxides, or
combinations thereof. The active material of the present disclosure is a cathode
15 active material.
[0023] The term “electrolyte” refers to a medium containing ions that are
electrically conductive through the movement of those ions, but not conducting
electrons. In an aspect of the present disclosure, the electrolyte includes a lithium
salt selected from LiPF6, LiFSi, or LiTFSi; and a solvent selected from diethylene
20 carbonate, dimethyl carbonate, ethyl methyl carbonate, or combinations thereof.
[0024] The term “conductive carbon” refers to a carbon-based material added to an
electrode composition which can form electronically conductive networks to
enhance the conductivity of the electrode. In an aspect of the present disclosure, the
conductive carbon comprises a primary conductive carbon and a secondary
25 conductive carbon.
[0025] The term “primary conductive carbon” refers to a nano-sized tubular
carbon-based material which enhances the conductivity and provides mechanical
integrity to the electrode. In an aspect of the present disclosure, the primary
conductive carbon is selected from single walled carbon nanotube (SWCNT),
6
multiwalled carbon nanotube (MWCNT), carbon nanofiber, vapour grown carbon
nanofiber, or combinations thereof.
[0026] The term “secondary conductive carbon” refers to a carbon-based material
which enhances the conductivity of the electrode. In an aspect of the present
5 disclosure, the secondary conductive carbon is selected from graphite, graphene,
carbon black, acetylene black, or combinations thereof.
[0027] The term “electrochemical cell” refers to a device that generates electrical
energy from chemical reactions. In the present disclosure, electrochemical cell is
comprised of (a) an anode; (b) a cathode and (c) an electrolyte.
10 [0028] The term “current collector” refers to the electric bridging component which
collects electrical current generated at the electrodes of electrochemical devices and
connects with external circuits. In an aspect of the present disclosure, the current
collector includes but not limited to aluminium foil, carbon coated aluminium foil,
primer coated aluminium foil, or glossy aluminium foil.
15 [0029] The term “binder solution” refers to a mixture comprising a binder with
solvent. The term “binder” refers to a polymeric material that helps to maintain the
integrity of the electrode coating, to bind the active material particles and
conducting carbon particles together and to ensure that the active material particles
adhere well to the current collector. In an aspect of the present disclosure, binder is
20 selected from polyvinylidene fluoride (PVDF), polypropylene carbonate (PPC),
poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), polyfluoroxy
alkanes (PFA), polyvinyl fluoride (PVF), polyethylene (PE), polyethylene vinyl
acetate (PEVA), polyethylene glycol (PEG), polyurethane (PU), polypropylene
rubber (PPR), ethylene propylene rubber (EPR), polyisobutylene (PIB), polyvinyl
25 alcohol (PVA), phenoxy resin, polyethylene terephthalate (PET), nylon, polymethyl
methacrylate (PMMA), polyvinyl chloride (PVC), polyphenylene sulphide (PPS),
poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS),
polystyrene (PS), or combinations thereof; and the solvent is selected from Nmethyl pyrrolidone, dimethyl formamide, dimethyl sulfoxide, ethylene carbonate,
30 ethylene glycol, glycerol, or combinations thereof.
7
[0030] The term “calendering” refers to the process of compressing or pressing to
coat an active material-containing layer upon a substrate/current collector by
passing through a set of heated rollers so as to achieve properties such as reducing
thickness, reducing the porosity and the like. A material comprising a layer having
5 at least one polymer and at least one active material coated on a substrate (current
collector) is calendered to improve adhesion of the layer on to the substrate surface
and achieve desired thickness of the material. The process is carried out for
incorporating desired properties to the material. In an aspect the present disclosure,
the term calendering refers to the process by which the electrode slurry coated on a
10 current collector is pressed to form an electrode having uniform thickness and
porosity.
[0031] The term “through plane resistance” refers to a measure of the opposition to
the flow of current within a material, measured through the thickness of the
material. In an aspect of the present disclosure, there is provided an electrode having
15 a through plane resistance in a range of 0.2 to 0.5 Ohms.
[0032] 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
20 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, blending
carried out for a period in a range of 5 to 20 minutes should be interpreted to include
not only the explicitly recited limits of 5 to 20 minutes but also to include subranges, such as 8 to 18 minutes, 10 to 15 minutes and so forth, as well as individual
25 amounts, including fractional amounts, within the specified ranges, such as 7.5
minutes, 10.5 minutes, 15 minutes, and 16.5 minutes.
[0033] 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
30 equivalent to those described herein can be used in the practice or testing of the
8
disclosure, the preferred methods and materials are now described. All publications
mentioned herein are incorporated herein by reference.
[0034] The present disclosure is not to be limited in scope by the specific
embodiments described herein, which are intended for the purposes of
5 exemplification only. Functionally equivalent products, compositions,
formulations, and methods are clearly within the scope of the disclosure, as
described herein.
[0035] As discussed in the background, many challenges exist in developing an
efficient battery electrode. The existing processes for the development of electrodes
10 result in agglomeration of conductive additives, leading to dendritic growth or
short-circuiting while prolonged cycling. All of these resulted in increasing internal
resistance or in other words lowering of electrochemical performance. In view of
the existing shortcomings in electrode preparation processes, the present disclosure
provides a process for preparing electrodes by varying the battery electrode
15 manufacturing process by utilizing conductive carbon having specific morphology
to avoid agglomeration. Two different kinds of conductive carbons, namely nanosized tubular carbon (primary conductive carbon; like carbon nanotube (CNT),
carbon nanofiber (CNF) etc.,) and particle-type (secondary conductive carbon like
carbon black (e.g., super P,), graphite etc.,) which were feasible in terms of the
20 particle size and morphology, provides an optimum carbon coverage over the
cathode active material surface and also facilitated in the electronic networking.
[0036] Among the nano-sized tubular carbons, there are single-walled and multiwalled carbon nanotubes which have been used as conductive carbons in electrodes.
Owing to the desired tubular morphology with aspect ratio in a range of 50 to 4000,
25 the present disclosure provides a process for preparing an electrode, wherein the
MWCNT is employed as the primary conductive carbon to facilitate electronic
networking between the active material particles. Along with a tubular conductive
carbon, the process of the present disclosure employes a particle-type carbon such
as super P as a secondary conductive carbon for the cathode active material. The
30 MWCNT having a comparable particle size with super P, which helped in achieving
9
a homogeneous mixture with a cathode active material and a binder. However, when
the electrode mixture was prepared using higher amounts of conductive carbons
there were challenges of carbon agglomerations, when not mixed properly.
Therefore, the present disclosure provides a process wherein stepwise sequential
5 mixing was adopted to reduce the carbon agglomeration which will confer the
homogeneous electrical conductivity in the electrodes throughout its length and
thereby prevent the development of internal resistance.
[0037] Accordingly, the present disclosure provides a process for preparing an
electrode, the process comprising: (a) mixing a primary conductive carbon with a
10 binder solution to obtain a pre-mixture; (b) blending a first part of an active material
with the pre-mixture to obtain a blend; (c) adding a first part of a secondary
conductive carbon to the blend and stirring to obtain a first mixture; (d) adding a
second part of the active material with the first mixture to obtain a second mixture;
(e) mixing a second part of the secondary conductive carbon with the second
15 mixture, followed by high-speed mixing to obtain an electrode slurry; and (f)
processing of the electrode slurry to obtain the electrode, wherein the primary
conductive carbon and the secondary conductive carbon are in a weight ratio range
of 1:0.75 to 1:1.5, wherein the combined weight of the primary conductive carbon
and the secondary conductive carbon is in a range of 1 to 2%, with respect to the
20 total weight of the electrode.
[0038] In an embodiment of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: (a) mixing a primary conductive
carbon with a binder solution to obtain a pre-mixture; (b) blending a first part of an
active material with the pre-mixture to obtain a blend; (c) adding a first part of a
25 secondary conductive carbon to the blend and stirring to obtain a first mixture; (d)
adding a second part of the active material with the first mixture to obtain a second
mixture; (e) mixing a second part of the secondary conductive carbon with the
second mixture, followed by high-speed mixing to obtain an electrode slurry; and
(f) processing of the electrode slurry to obtain the electrode, wherein the primary
30 conductive carbon and the secondary conductive carbon are in a weight ratio range
10
of 1:0.75 to 1:1.5, and wherein the combined weight of the primary conductive
carbon and the secondary conductive carbon is in a range of 1 to 2%, with respect
to the total weight of the electrode. In another embodiment of the present disclosure,
the primary conductive carbon and the secondary conductive carbon are in a weight
5 ratio range of 1:0.8 to 1:1.35, and wherein the combined weight of the primary
conductive carbon and the secondary conductive carbon is in a range of 1.2 to 1.8%,
with respect to the total weight of the electrode. In yet another embodiment of the
present disclosure, the primary conductive carbon and the secondary conductive
carbon are in a weight ratio range of 1:0.9 to 1:1.1, and wherein the combined
10 weight of the primary conductive carbon and the secondary conductive carbon is in
a range of 1.4 to 1.6%, with respect to the total weight of the electrode. In still
another embodiment of the present disclosure, the primary conductive carbon and
the secondary conductive carbon are in a weight ratio range of 1:0.95 to 1:1.05, and
wherein the combined weight of the primary conductive carbon and the secondary
15 conductive carbon is in a range of 1.45 to 1.55%, with respect to the total weight of
the electrode.
[0039] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the primary conductive carbon is in a weight range of 0.5
to 1%, with respect to the total weight of the electrode; and the primary conductive
20 carbon is selected from single walled carbon nanotube (SWCNT), multiwalled
carbon nanotube (MWCNT), carbon nanofiber, vapour grown carbon nanofiber or
combinations thereof. In another embodiment of the present disclosure, the primary
conductive carbon is in a weight range of 0.6 to 0.9%, with respect to the total
weight of the electrode; and the primary conductive carbon is selected from single
25 walled carbon nanotube (SWCNT), multiwalled carbon nanotube (MWCNT), or
combinations thereof. In yet another embodiment of the present disclosure, the
primary conductive carbon is in a weight range of 0.7 to 0.8%, with respect to the
total weight of the electrode; and the primary conductive carbon is multiwalled
carbon nanotube (MWCNT).
11
[0040] In an embodiment of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: (a) mixing 0.5 to 1% by weight of
a primary conductive carbon with a binder solution to obtain a pre-mixture; (b)
blending a first part of an active material with the pre-mixture to obtain a blend; (c)
5 adding a first part of a secondary conductive carbon to the blend and stirring to
obtain a first mixture; (d) adding a second part of the active material with the first
mixture to obtain a second mixture; (e) mixing a second part of the secondary
conductive carbon with the second mixture, followed by high-speed mixing to
obtain an electrode slurry; and (f) processing of the electrode slurry to obtain the
10 electrode, wherein the primary conductive carbon and the secondary conductive
carbon are in a weight ratio range of 1:0.75 to 1:1.5, and wherein the combined
weight of the primary conductive carbon and the secondary conductive carbon is in
a range of 1 to 2%, with respect to the total weight of the electrode.
[0041] In an embodiment of the present disclosure, there is provided a process as
15 disclosed herein, wherein the first part of the secondary conductive carbon and the
second part of the secondary conductive carbon are in a weight ratio range of 1:0.75
to 1:1.5. In another embodiment of the present disclosure, the first part of the
secondary conductive carbon and the second part of the secondary conductive
carbon are in a weight ratio range of 1:0.8 to 1:1.3. In yet another embodiment of
20 the present disclosure, the first part of the secondary conductive carbon and the
second part of the secondary conductive carbon are in a weight ratio range of 1:0.9
to 1:1.1.
[0042] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the first and the second part of the secondary conductive
25 carbon combinedly is in a weight range of 0.5 to 1%, with respect to the total weight
of the electrode; and the secondary conductive carbon is selected from graphite,
graphene, carbon black (ketjen black 600JD, Super P C45, Super P C65, Super P
C65T, ketjen black 300, or Vulcan carbon), acetylene black, or combinations
thereof. In another embodiment of the present disclosure, the first and the second
30 part of the secondary conductive carbon combinedly is in a weight range of 0.6 to
12
0.9%, with respect to the total weight of the electrode; and the secondary conductive
carbon is selected from carbon black (Super P C45, Super P C65, Super P C65T, or
Vulcan carbon), acetylene black, or combinations thereof. In yet another
embodiment of the present disclosure, the first and the second part of the secondary
5 conductive carbon combinedly is in a weight range of 0.7 to 0.8%, with respect to
the total weight of the electrode; and the secondary conductive carbon is carbon
black (Super P C45, Super P C65, or Super P C65T).
[0043] In an embodiment of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: (a) mixing 0.5 to 1% by weight of
10 a primary conductive carbon with a binder solution to obtain a pre-mixture; (b)
blending a first part of an active material with the pre-mixture to obtain a blend; (c)
adding a first part of a secondary conductive carbon to the blend and stirring to
obtain a first mixture; (d) adding a second part of the active material with the first
mixture to obtain a second mixture; (e) mixing a second part of the secondary
15 conductive carbon with the second mixture, followed by high-speed mixing to
obtain an electrode slurry; and (f) processing of the electrode slurry to obtain the
electrode, wherein the primary conductive carbon and the secondary conductive
carbon are in a weight ratio range of 1:0.75 to 1:1.5; wherein the combined weight
of the primary conductive carbon and the secondary conductive carbon is in a range
20 of 1 to 2%, with respect to the total weight of the electrode; wherein the first and
the second part of the secondary conductive carbon combinedly is in a weight range
of 0.5 to 1%, with respect to the total weight of the electrode; and the second
secondary conductive carbon is selected from graphite, graphene, carbon black,
acetylene black, or combinations thereof.
25 [0044] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the binder solution is a mixture of a binder with a solvent.
[0045] In an embodiment of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: (a) mixing a binder with a solvent
to obtain a binder solution; (b) mixing a primary conductive carbon with the binder
30 solution to obtain a pre-mixture; (c) blending a first part of an active material with
13
the pre-mixture to obtain a blend; (d) adding a first part of a secondary conductive
carbon to the blend and stirring to obtain a first mixture; (e) adding a second part of
the active material with the first mixture to obtain a second mixture; (f) mixing a
second part of the secondary conductive carbon with the second mixture, followed
5 by high-speed mixing to obtain an electrode slurry; and (g) processing of the
electrode slurry to obtain the electrode, wherein the secondary conductive carbon
is carbon black. In another embodiment of the present disclosure, the carbon black
is ketjen black 600JD, Super P C45, Super P C65, Super P C65T, ketjen black 300,
or Vulcan carbon. In yet another embodiment of the present disclosure, the carbon
10 black is Super P C45, Super P C65, or Super P C65T.
[0046] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the binder is in a weight range of 1 to 2%, with respect to
total weight of the electrode; the binder is selected from polyvinylidene fluoride
(PVDF), polypropylene carbonate (PPC), poly(vinylidene fluoride15 hexafluoropropylene) (PVDF-HFP), polyfluoroxy alkanes (PFA), polyvinyl
fluoride (PVF), polyethylene (PE), polyethylene vinyl acetate (PEVA),
polyethylene glycol (PEG), polyurethane (PU), polypropylene rubber (PPR),
ethylene propylene rubber (EPR), polyisobutylene (PIB), polyvinyl alcohol (PVA),
phenoxy resin, polyethylene terephthalate (PET), nylon, polymethyl methacrylate
20 (PMMA), polyvinyl chloride (PVC), polyphenylene sulphide (PPS), poly(3,4-
ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polystyrene (PS), or
combinations thereof; and the solvent is selected from N-methyl pyrrolidone,
dimethyl formamide, dimethyl sulfoxide, ethylene carbonate, ethylene glycol,
glycerol, or combinations thereof. In another embodiment of the present disclosure,
25 the binder is in a weight range of 1.2 to 1.8%, with respect to total weight of the
electrode; the binder is selected from polyvinylidene fluoride (PVDF),
polypropylene carbonate (PPC), poly(vinylidene fluoride-hexafluoropropylene)
(PVDF-HFP), polyfluoroxy alkanes (PFA), polyvinyl fluoride (PVF), polyethylene
(PE), polyethylene vinyl acetate (PEVA), or combinations thereof; and the solvent
30 is selected from N-methyl pyrrolidone, dimethyl formamide, dimethyl sulfoxide, or
combinations thereof. In yet an embodiment of the present disclosure, the binder is
14
in a weight range of 1.4 to 1.6%, with respect to total weight of the electrode; the
binder is polyvinylidene fluoride (PVDF), or poly(vinylidene fluoridehexafluoropropylene) (PVDF-HFP); and the solvent is N-methyl pyrrolidone.
[0047] In an embodiment of the present disclosure, there is provided a process as
5 disclosed herein, wherein the solvent is in a weight range of 20 to 25%, with respect
to total weight of the electrode slurry. In another embodiment of the present
disclosure, the solvent is in a weight range of 21 to 24.5%, with respect to total
weight of the electrode slurry. In another embodiment of the present disclosure, the
solvent is in a weight range of 23 to 24%, with respect to total weight of the
10 electrode slurry.
[0048] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the binder solution is a mixture of 1 to 2% by weight of
a binder (with respect to total weight of the electrode) selected from polyvinylidene
fluoride (PVDF), polypropylene carbonate (PPC), poly(vinylidene fluoride15 hexafluoropropylene) (PVDF-HFP), polyfluoroxy alkanes (PFA), polyvinyl
fluoride (PVF), polyethylene (PE), polyethylene vinyl acetate (PEVA),
polyethylene glycol (PEG), polyurethane (PU), polypropylene rubber (PPR),
ethylene propylene rubber (EPR), polyisobutylene (PIB), polyvinyl alcohol (PVA),
phenoxy resin, polyethylene terephthalate (PET), nylon, polymethyl methacrylate
20 (PMMA), polyvinyl chloride (PVC), polyphenylene sulphide (PPS), poly(3,4-
ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polystyrene (PS), or
combinations thereof, with 20 to 25% by weight of a solvent (with respect to total
weight of the electrode slurry) selected from N-methyl pyrrolidone, dimethyl
formamide, dimethyl sulfoxide, ethylene carbonate, ethylene glycol, glycerol, or
25 combinations thereof.
[0049] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein the first part of the active material and the second part of
the active material are in a weight ratio range of 1: 0.75 to 1: 1.5. In another
embodiment of the present disclosure, the first part of the active material and the
30 second part of the active material are in a weight ratio range of 1: 0.8 to 1: 1.2. In
15
yet another embodiment of the present disclosure, the first part of the active material
and the second part of the active material are in a weight ratio range of 1: 0.9 to 1:
1.1.
[0050] In an embodiment of the present disclosure, there is provided a process for
5 preparing an electrode, the process comprising: (a) mixing a primary conductive
carbon with a binder solution to obtain a pre-mixture; (b) blending a first part of an
active material with the pre-mixture to obtain a blend; (c) adding a first part of a
secondary conductive carbon to the blend and stirring to obtain a first mixture; (d)
adding a second part of the active material with the first mixture to obtain a second
10 mixture; (e) mixing a second part of the secondary conductive carbon with the
second mixture, followed by high-speed mixing to obtain an electrode slurry; and
(f) processing of the electrode slurry to obtain the electrode, wherein the primary
conductive carbon and the secondary conductive carbon are in a weight ratio range
of 1:0.75 to 1:1.5; wherein the combined weight of the primary conductive carbon
15 and the secondary conductive carbon are in a range of 1 to 2%, with respect to the
total weight of the electrode; and wherein the first part of the active material and
the second part of the active material are in a weight ratio range of 1: 0.75 to 1: 1.5.
[0051] In an embodiment of the present disclosure, there is provided a process
for preparing an electrode, the process comprising: (a) mixing a primary conductive
20 carbon with a binder solution to obtain a pre-mixture; (b) blending a first part of an
active material with the pre-mixture to obtain a blend; (c) adding a first part of a
secondary conductive carbon to the blend and stirring to obtain a first mixture; (d)
adding a second part of the active material with the first mixture to obtain a second
mixture; (e) mixing a second part of the secondary conductive carbon with the
25 second mixture, followed by high-speed mixing to obtain an electrode slurry; and
(f) processing of the electrode slurry to obtain the electrode, wherein the primary
conductive carbon and the secondary conductive carbon are in a weight ratio range
of 1:0.75 to 1:1.5, wherein the combined weight of the primary conductive carbon
and the secondary conductive carbon are in a range of 1 to 2%, with respect to the
30 total weight of the electrode, wherein first and the second part of the active material
16
combinedly is in a weight range of 96 to 98% with respect to total weight of the
electrode; and the active material is selected from lithium nickel manganese oxide
(NMC), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron
phosphate (LFP), lithium yttrium iron phosphate (LYP), lithium nickel manganese
5 cobalt oxide, lithium nickel cobalt aluminium oxide (NCA), lithium manganese
phosphate (LiMnPO4), lithium cobalt phosphate (LiCoPO4), lithium vanadium
phosphate (LVP), spinel type alkali metal transition metal oxides, alkali-transition
metal oxides (AMO2; A is alkali metal and M is transition metal) oxides, or
combinations thereof. In another embodiment of the present disclosure, first and the
10 second part of the active material combinedly is in a weight range of 96.5 to 97.5%
with respect to total weight of the electrode; and the active material is selected from
lithium nickel manganese cobalt oxide, spinel lithium nickel manganese oxide, or
lithium iron phosphate. In yet another embodiment of the present disclosure, first
and the second part of the active material combinedly is in a weight range of 96.8
15 to 97.2% with respect to total weight of the electrode; and the active material is
lithium nickel manganese cobalt oxide.
[0052] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein mixing in step (a) is carried out at a speed in a range of
200 to 800rpm for a time period ranging from 10 to 20 minutes. In another
20 embodiment of the present disclosure, mixing in step (a) is carried out at a speed in
a range of 300 to 700rpm for a time period ranging from 12 to 18 minutes. In yet
another embodiment of the present disclosure, mixing in step (a) is carried out at a
speed in a range of 400 to 600rpm for a time period ranging from 14 to 16 minutes.
[0053] In an embodiment of the present disclosure, there is provided a process as
25 disclosed herein, wherein blending in step (b) is carried out by stirring at a speed in
a range of 800 to 1200 rpm, for a period in a range of 5 to 20 minutes. In another
embodiment of the present disclosure, blending in step (b) is carried out by stirring
at a speed in a range of 900 to 1100 rpm, for a period in a range of 7 to 17 minutes.
In yet another embodiment of the present disclosure, blending in step (b) is carried
17
out by stirring at a speed in a range of 950 to 1050 rpm, for a period in a range of 9
to 12 minutes.
[0054] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein stirring in step (c) is carried out at a speed in a range of
5 800 to 1200 rpm, for a period in a range of 5 to 20 minutes. In another embodiment
of the present disclosure, stirring in step (c) is carried out at a speed in a range of
900 to 1100 rpm, for a period in a range of 7 to 17 minutes. In yet another
embodiment of the present disclosure, stirring in step (c) is carried out at a speed in
a range of 950 to 1050 rpm, for a period in a range of 9 to 12 minutes.
10 [0055] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein step (d) comprises agitation at a speed in a range of 800
to 1200 rpm, for a period in a range of 5 to 20 minutes. In another embodiment of
the present disclosure, step (d) comprises agitation at a speed in a range of 900 to
1100 rpm, for a period in a range of 7 to 17 minutes. In yet another embodiment of
15 the present disclosure, step (d) comprises agitation at a speed in a range of 950 to
1050 rpm, for a period in a range of 8 to 12 minutes.
[0056] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein mixing in step (e) is carried out at a speed in a range of
800 to 1200 rpm, for a period in a range of 5 to 20 minutes. In another embodiment
20 of the present disclosure, mixing in step (e) is carried out at a speed in a range of
900 to 1100 rpm, for a period in a range of 7 to 17 minutes. In yet another
embodiment of the present disclosure, mixing in step (e) is carried out at a speed in
a range of 950 to 1050 rpm, for a period in a range of 9 to 12 minutes
[0057] In an embodiment of the present disclosure, there is provided a process as
25 disclosed herein, wherein the high-speed mixing in step (e) is carried out at a speed
in a range of 1600 to 2500 rpm for a period in a range of 130 to 200 minutes. In
another embodiment of the present disclosure, high-speed mixing in step (e) is
carried out at a speed in a range of 1700 to 2400 rpm, for a period in a range of 140
to 190 minutes. In yet another embodiment of the present disclosure, high-speed
18
mixing in step (e) is carried out at a speed in a range of 1800 to 2000 rpm, for a
period in a range of 170 to 190 minutes. In still another embodiment of the present
disclosure, high-speed mixing in step (e) is carried out in two steps: first high-speed
mixing at a speed in a range of 1700 to 1900 rpm, for a period in a range of 50 to
5 80 minutes, followed by second high-speed mixing at a speed in a range of 1900 to
2100 rpm, for a period in a range of 100 to 130 minutes.
[0058] In an embodiment of the present disclosure, there is provided a process for
preparing an electrode, the process comprising: (a) mixing a primary conductive
carbon with a binder solution at a speed in a range of 200 to 800rpm for a time
10 period ranging from 10 to 20 mins to obtain a pre-mixture; (b) blending a first part
of an active material with the pre-mixture at a speed in a range of 800 to 1200 rpm,
for a period in a range of 5 to 20 minutes to obtain a blend; (c) adding a first part of
a secondary conductive carbon to the blend and stirring at a speed in a range of 800
to 1200 rpm, for a period in a range of 5 to 20 minutes to obtain a first mixture; (d)
15 adding a second part of the active material with the first mixture at a speed in a
range of 800 to 1200 rpm, for a period in a range of 5 to 20 minutes to obtain a
second mixture; (e) mixing a second part of the secondary conductive carbon with
the second mixture at a speed in a range of 800 to 1200 rpm, for a period in a range
of 5 to 20 minutes, followed by high-speed mixing at a speed in a range of 1600 to
20 2500 rpm for a period in a range of 130 to 200 minutes to obtain an electrode slurry;
and (f) processing of the electrode slurry to obtain the electrode, wherein the
primary conductive carbon and the secondary conductive carbon are in a weight
ratio range of 1:0.75 to 1:1.5; and wherein the combined weight of the primary
conductive carbon and the secondary conductive carbon is in a range of 1 to 2%,
25 with respect to the total weight of the electrode.
[0059] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein processing comprises coating the electrode slurry on a
substrate, drying, calendering, or combinations thereof.
[0060] In an embodiment of the present disclosure, there is provided a process as
30 disclosed herein, wherein the substrate is a current collector selected from
19
aluminium foil, carbon coated aluminium foil, primer coated aluminium foils, or
glossy aluminium foil. In another embodiment of the present disclosure, the current
collector is aluminium foil.
[0061] In an embodiment of the present disclosure, there is provided a process as
5 disclosed herein, wherein processing comprises coating the electrode slurry on a
current collector selected from aluminium foil, carbon coated copper aluminium
foil, primer coated aluminium foil, or glossy aluminium foil, drying, calendering,
or combinations thereof.
[0062] In an embodiment of the present disclosure, there is provided a process for
10 preparing an electrode, the process comprising: (a) mixing a primary conductive
carbon with a binder solution to obtain a pre-mixture; (b) blending a first part of an
active material with the pre-mixture to obtain a blend; (c) adding a first part of a
secondary conductive carbon to the blend and stirring to obtain a first mixture; (d)
adding a second part of the active material with the first mixture to obtain a second
15 mixture; (e) mixing a second part of the secondary conductive carbon with the
second mixture, followed by high-speed mixing to obtain an electrode slurry; and
(f) processing of the electrode slurry to obtain the electrode, wherein the primary
conductive carbon and the secondary conductive carbon are in a weight ratio range
of 1:0.75 to 1:1.5; wherein the combined weight of the primary conductive carbon
20 and the secondary conductive carbon is in a range of 1 to 2%, with respect to the
total weight of the electrode; and wherein processing comprises coating the
electrode slurry on a substrate which is a current collector selected from aluminium
foil, carbon coated aluminium foil, primer coated aluminium foil, or glossy
aluminium foil, followed by drying, and calendering.
25 [0063] In an embodiment of the present disclosure, there is provided a process as
disclosed herein, wherein processing comprises: (a) coating the electrode slurry on
a substrate to obtain a coated substrate, (b) drying the coated substrate by passing
through a chamber maintained at 90 to 140℃ and at a speed in a range of 1 to 5
m/min to obtain a dried substrate, and (c) calendering the dried substrate by passing
30 through a set of rollers wherein roller temperature is in a range of 50 to 70 ℃, roller
20
speed is in a range of 60 to 80 m/min and the load applied on the dried substrate is
in a range of 380 to 430kN to obtain the electrode.
[0064] In an embodiment of the present disclosure, there is provided a an electrode
obtained by the process as disclosed herein, wherein the electrode comprises: (a) an
5 active material; (b) a binder; (c) a primary conductive carbon; and (d) a secondary
conductive carbon, wherein the primary conductive carbon and the secondary
conductive carbon are present in a weight ratio range of 1: 0.75 to 1: 1.5.
[0065] In an embodiment of the present disclosure, there is provided an electrode
as disclosed herein, wherein the combined weight of the primary conductive carbon
10 and the secondary conductive carbon is in a range of 1 to 2%, with respect to the
total weight of the electrode. In another embodiment of the present disclosure, the
combined weight of the primary conductive carbon and the secondary conductive
carbon is in a range of 1.2 to 1.8%, with respect to the total weight of the electrode.
In yet another embodiment of the present disclosure, the combined weight of the
15 primary conductive carbon and the secondary conductive carbon is in a range of 1.4
to 1.6%, with respect to the total weight of the electrode.
[0066] In an embodiment of the present disclosure, there is provided an electrode
as disclosed herein, wherein the electrode is a cathode.
[0067] In an embodiment of the present disclosure, there is provided an electrode
20 as disclosed herein, wherein the electrode is a cathode, and the cathode has a
through plane resistance in a range of 0.2 to 0.5 Ohms. In another embodiment of
the present disclosure, the cathode has a through plane resistance in a range of 0.3
to 0.5 Ohms. In yet another embodiment of the present disclosure, the cathode has
a through plane resistance in a range of 0.35 to 0.45 Ohms.
25 [0068] In an embodiment of the present disclosure, there is provided an
electrochemical cell comprising: (a) an anode; (b) a cathode comprising the
electrode obtained by the process as disclosed herein; and (c) an electrolyte.
[0069] In an embodiment of the present disclosure, there is provided an
electrochemical cell comprising: (a) an anode selected from synthetic graphite,
21
natural graphite, or silicon-graphite composite; (b) a cathode comprising the
electrode obtained by the process as disclosed herein; and (c) an electrolyte.
[0070] In an embodiment of the present disclosure, there is provided an
electrochemical cell comprising: (a) an anode; (b) a cathode comprising the
5 electrode obtained by the process as disclosed herein; and (c) an electrolyte
comprising a lithium salt selected from LiPF6, LiFSi, or LiTFSi, and a solvent
selected from diethylene carbonate, dimethyl carbonate, ethyl methyl carbonate,
vinyl carbonate, or combinations thereof.
[0071] In an embodiment of the present disclosure, there is provided an
10 electrochemical cell comprising: (a) an anode selected from synthetic graphite,
natural graphite, or silicon-graphite composite; (b) a cathode comprising the
electrode obtained by the process as disclosed herein; and (c) an electrolyte
comprising a lithium salt selected from LiPF6, LiFSi, or LiTFSi, and a solvent
selected from diethylene carbonate, dimethyl carbonate, ethyl methyl carbonate,
15 vinyl carbonate, or combinations thereof
[0072] In an embodiment of the present disclosure, there is provided a use of the
electrode obtained by the process disclosed herein as a cathode in an
electrochemical cell.
[0073] Although the subject matter has been described in considerable detail with
20 reference to certain examples and implementations thereof, other implementations
are possible.

EXAMPLES
[0074] The disclosure will now be illustrated with following examples, which is
25 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 to or equivalent to those described
22
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.
5 Materials and Methods
[0075] The various chemicals and solvents used in the present disclosure are as
follows:
a. Active Material:
Cathode material- lithium nickel manganese cobalt (NMC811)
10 b. Conductive carbonMulti-walled carbon nanotube (MWCNT; primary conductive carbon)
having a particle size of 7-100 nm and an aspect ratio of 50 to 4000; and
Super P65T (carbon black; secondary conductive carbon),
c. Binder- Polyvinylidene fluoride (PVDF)
15 d. Solvent- N-methyl pyrrolidone (NMP).
For full cell preparation:
Anode active material synthetic graphite (96) was procured from Zichen,
binder carboxymethyl cellulose (CMC), binder styrene butadiene rubber
(SBR), Super-P, and polypropylene (PP) separator was procured from
20 SEMCORP.
EXAMPLE 1
Preparation of the Electrode of the present disclosure
[0076] The present example explains the process 1 for preparing the electrode.
25 [0077] A binder solution was prepared by mixing 100mL of N-methyl pyrrolidone
(solvent) and 1.5 wt% of polyvinylidene fluoride (binder) at a stirring speed of 1300
rpm for 12 hours at room temperature. 0.75 wt% of MWCNT (primary conductive
carbon) was added to the binder solution and was mixed at a speed of 500 rpm for
23
15 minutes to obtain a pre-mixture (step a). To the pre-mixture, 48.5 wt% (first part)
of NMC811 (active material) was added and blended at a speed of 1000 rpm for 10
minutes to obtain a blend (step b). Followed by this, 0.375 wt% (first part) of Super
P (carbon black; secondary conductive carbon) was added to the blend and stirred
5 at a speed of 1000 rpm for 10 minutes to obtain a first mixture (step c). The
remaining 48.5 wt% (second part) of the NMC811 was added to the first mixture
and agitated at a speed of 1000 rpm for 10 minutes to obtain a second mixture (step
d). Subsequently, the remaining 0.375 wt% (second part) of Super P was added to
the second mixture and mixed for another 10 minutes at 1000 rpm, followed by a
10 high-speed mixing which was carried out in two steps: in first high-speed mixing,
the mixing was carried out at a speed of 2000 rpm for 60 minutes, and in second
high-speed mixing, the mixing was carried at 1800 rpm for 120 minutes to obtain
an electrode slurry (ES) which was then subjected to degassing.
[0078] The electrode slurry (ES) was coated upon aluminium foil (a current
15 collector) and dried by passing it through a chamber maintained at 90 to 140℃ and
at a speed in a range of 1 to 5 m/min. Further, the dried electrode slurry coated
substrate was calendered by passing it through a set of rollers wherein roller
temperature was in a range of 50 to 70 ℃, roller speed was in a range of 60 to 80
m/min and the load applied was in a range of 380 to 430kN to obtain the electrode
20 (EA).
EXAMPLE 2:
Preparation of the comparative electrode CE-1
[0079] The present example provides a comparative process 2 for preparing
25 comparative electrode CE-1. The comparative electrode CE-1 was prepared by
obtaining the electrode slurry via following the process as explained in Example 1,
except the combined weight% of primary and secondary conductive carbons was
0.7%, and the secondary conductive carbon was added as a whole instead of adding
in two parts (first part and second part). Further, the electrode slurry was coated
30 upon an aluminium foil (current collector) to obtain the comparative electrode CE1. The detailed process for preparation of CE-1 is provided below.
24
[0080] A binder solution was prepared by taking N-methyl pyrrolidone (solvent)
and 1.5 wt% of Polyvinylidene fluoride (binder) and mixed at a speed of 1300 rpm
for 12 hours at room temperature. 0.5 wt% of MWCNT (primary conductive
carbon) was added to the binder solution and was mixed at a speed of 1500 rpm for
5 15 minutes to obtain a mixture-1. Further, 48.5 wt% of the NMC811 (active
material) was added to the mixture-1 and was blended at a speed of 2000 rpm for
30 minutes to obtain mixture-2. Followed by this, the remaining 48.5 wt% of the
NMC811 was added to the mixture-2 and was mixed at a speed of 2000 rpm for 60
minutes to obtain mixture-3. Subsequently, 0.2 wt% Super P (secondary conductive
10 carbon) was mixed with the mixture-3, at a speed of 1500 rpm for 40 minutes to
obtain a mixture-4. Finally, the mixture-4 was mixed for 120 minutes at 1800 rpm
to obtain a mixture-5, followed by degassing to obtain the electrode slurry CS-1.
[0081] The slurry CS-1 obtained by the comparative process 2, was then coated
upon a current collector aluminium foil (substrate) and dried by passing through a
15 chamber maintained at 90 to 140℃ and at a speed in a range of 1 to 5 m/min.
Further, the dried substrate was calendered by passing through a set of rollers
wherein roller temperature was in a range of 50 to 70 ℃, roller speed was in a range
of 60 to 80 m/min and the load applied was in a range of 380 to 430kN to obtain
the electrode CE-1.
20 [0082] Similarly, various comparative electrodes employing binder and conductive
carbons (primary and secondary) in different weight percentages using the
comparative process 2 as provided above were prepared. The composition of
various comparative electrodes is provided in the Table 1.
25 Table 1
Sample Code
NMC
(weight %)
PVDF
(weight %)
MWCNT
(weight %)
Super P
(weight %)
CE-1 97.8 1.5 0.5 0.2
CE-2 97.0 1.5 0.5 1.0
CE-3
97.0 1.5
0.75
(SWCNT)
0.75
CE-4 97.0 1.5 0.75 0.75
25
CE-5 97.3 1.2 0.75 0.75
[0083] In electrode CE-3, single walled carbon nanotube (SWCNT) of aspect ratio
more than 10000 and length of 0.5 to 2.5nm was used instead of MWCNT.
Meanwhile, the MWCNT used in other electrodes CE-1, CE, 2, CE-4, and CE-5
5 had an aspect ratio of 50 to 4000 and length of 7 to 100nm.
EXAMPLE 3
Characterisation of the electrodes
[0084] The present example shows the characterization results of the electrodes EA
10 (prepared by the process 1), along with CE-1, CE-2, CE-3, CE-4 and CE-5
(prepared by the comparative process 2).
Field emission scanning electron microscopic (FESEM) analysis of the
electrodes
[0085] The topographic morphology of the electrodes prepared from the processes
15 disclosed herein was analyzed using FESEM technique. The scanning electron
microscopic (SEM) images for the electrode EA prepared by the process 1, and
electrode CE-5 prepared by the comparative process 2 are shown in Figure 1(a) and
Figure 1(b), respectively.
[0086] The FESEM Figure 1(a) of the electrode EA showed that the particles of
20 conductive carbons MWCNT (primary conductive carbon) and Super P (secondary
conductive carbon), PVDF, and cathode active material NMC811 were distributed
homogeneously. Hence, it was confirmed that the electrode EA obtained by the
process 1 of the present disclosure resulted in enhanced distribution of the active
material, conductive carbons (primary and secondary), and binders (fibrillating and
25 adhesive) in the electrode.
[0087] FESEM image in Figure 1 (b) of the electrode CE-5 clearly exhibited carbon
agglomerates on the surface. Hence, the electrode EA of the present disclosure was
found to exhibit better homogenous distribution of conductive carbons throughout
the bulk of the electrode, than the electrode CE-5 prepared using the comparative
30 process 2.
26
Through plane resistivity of the electrodes
[0088] The through plane conductivity was analyzed by studying conductivity in
the direction perpendicular to the plane of the electrode film with two probe
electrode system. The various electrodes (EA, along with comparative electrodes
5 CE-1, CE-2, CE-3, and CE-4) exhibited a through plane conductivity around 0.2 to
3 mS/cm at 25 ℃. Figure 2 depicts the graphical representation of plane resistivity
exhibited by different cathode composition with various conducting additives.
[0089] Among all the electrodes analyzed, 1.5 wt% of conductive carbon content
with primary and secondary carbon in a weight ratio of 0.75: 0.75 (or 1:1) showed
10 the lowest resistance (0.44 Ohms) when the process 1 of the present disclosure was
adopted for the electrode preparation. Therefore, the weight ratio of primary and
secondary conductive carbons in a range of 1:0.75 to 1:1.5, along with the
sequential addition of components in parts were found to be critical to achieve an
electrode with better compactness and lesser resistance.
15 EXAMPLE 4
Preparation of an electrochemical cell
[0090] The electrochemical cell setup was obtained by sequentially assembling the
cathode prepared by the process as explained in Example 1, and an anode on either
side of an electrolyte.
20 [0091] For the purpose of electrochemical analysis of the cathode as explained in
Example 1, a full-cell was prepared using below cell components:
Cathode comprising the electrode EA prepared by the process as explained in
Example 1.
Anode comprising a synthetic graphite (96 wt%) from Zichen, CMC (1.5 wt%)
25 binder, SBR (1.8 wt%) binder, and Super-P (0.7 wt%) conducting additive in
aqueous medium coated on an anodic current collector.
Separator: polypropylene (PP) film.
Electrolyte comprising LiPF6 dispersed in a solvent mixture of ethylene carbonate
(EC), vinylene carbonate (VC) and dimethyl carbonate (DMC)
30 [0092] An electrochemical cell was prepared by assembling the cathode comprising
the electrode EA as explained in example 1, the above-mentioned anode disposed
27
to face the cathode, the above-mentioned electrolyte injected between the cathode
and anode, and the above-mentioned separator placed between cathode and anode.
The electrochemical cell obtained from the process explained above was analysed
for its electrochemical performance, C-rate performance, and charge-discharge
5 capacity.
Electrochemical analysis of the electrodes
[0093] The electrodes prepared using the process 1 and comparative process 2,
were subjected to electrochemical analysis in the form of a full-cell prepared by the
process as explained above. Various samples cells were prepared using the
10 electrode EA. The DCIR of these cells comprising the electrode EA as cathode, was
analyzed after the cell was subjected to formation cycle, before performing rate test
and after carrying out rate test, as provided in Table 2. The DCIR is an internal
resistance gradually developed in an electrode as a result of flow of current that in
turn leads to conductive carbon agglomeration.
15 [0094] Formation cycle is a protocol by which the cell or battery is subjected to
sequential charging-discharging steps to facilitate the formation of SEI layer in the
battery so as to result in ready usage of the battery with high electrochemical
performance and better capacity. The charge-discharge cycles of the nominal
capacity measurements were carried out at a rate of 0.5C charge/ 1C discharge for
20 different samples of the cells comprising the electrode EA.
[0095] Rate test is the analysis technique where the cells were assessed for the
electrochemical charge-discharge cycles, with c-rates of 0.1C/0.1C, 0.2C/0.2C,
0.5C/0.5C, 0.5C/1C, 0.5C/2C and 0.5C/3C. After the rate test, the cells were
subjected to DCIR measurement.
25 [0096] The below Table 2 shows the DCIR measurement of various cell samples
comprising electrode EA as cathode.
Table 2
Cell
number
Formation Cycle DCIR
[after
subjecting
DCIR
[Total]
[Before rate
test; mΩ]
DCIR
[After rate test
mΩ]
Charge Discharge ICE%
28
(mAh) (mAh) to
formation
cycle;
mΩ]
EA-1 25.34 23.24 91.73 5.17 5.01 5.19
EA-2 25.48 23.38 91.73 5.42 5.50 5.65
EA-3 25.46 23.25 91.32 5.33 5.79 5.79
EA-4 25.33 23.21 91.63 4.63 4.40 4.40
EA-5 25.45 23.37 91.84 5.88 5.96 5.96
EA-6 25.32 23.22 91.72 5.08 4.73 4.79
29
[0097] The below Table 3 shows the DCIR measurement of various cell samples
comprising electrode CE-1 as the cathode.
Table 3
Cell
number
Formation Cycle DCIR
[after
subjecting to
formation
cycle; mΩ]
DCIR [Total]
[Before rate
test; mΩ]
DCIR
[After
rate test
mΩ]
Charge
(mAh)
Discharge
(mAh)
ICE%
CE-1-1 25.83 23.30 90.18 4.74 4.73 6.04
CE-1-2 25.83 23.43 90.70 4.36 4.47 5.33
CE-1-3 25.87 23.44 90.60 4.49 4.54 5.10
CE-1-4 25.82 23.40 90.63 4.41 4.51 4.96
CE-1-5 26.49 22.72 85.77 5.20 6.45 9.89
CE-1-6 26.59 22.87 86.02 4.66 5.90 8.07
5 [0098] The below Table 4 shows the DCIR measurement of various cell samples
comprising electrode CE-2 as the cathode.
Table 4
Cell
number
Formation Cycle DCIR
[after subjecting
to formation
cycle; mΩ]
DCIR
[Total]
[Before rate
test; mΩ]
DCIR
[After
rate test
mΩ]
Charge
(mAh)
Discharge
(mAh)
ICE%
1 26.54 22.87 86.17 4.99 5.27 6.72
2 26.45 22.73 85.91 4.95 5.22 6.87
3 26.49 22.68 85.64 4.80 4.81 6.18
4 26.52 22.69 85.54 4.69 5.22 6.10
5 26.53 22.62 85.26 4.98 4.90 5.47
6 26.66 22.80 85.50 4.58 4.63 5.03
10
30
[0099] The below Table 5 shows the DCIR measurement of various cell samples
comprising electrode CE-3 as the cathode.
Table 5
Cell
number
Formation Cycle DCIR
[after
subjecting to
formation
cycle; mΩ]
DCIR
[Total]
[Before rate
test; mΩ]
DCIR
[After rate
Charge test mΩ]
(mAh)
Discharge
(mAh)
ICE%
1 26.52 22.63 85.35 4.79 5.32 5.93
2 26.45 22.65 85.63 4.49 4.41 5.07
3 26.58 22.72 85.49 4.77 4.76 5.31
4 26.68 22.82 85.54 4.98 4.86 5.54
5 25.91 23.58 90.99 5.65 5.78 6.56
6 26.57 22.67 85.31 5.19 5.63 6.10
5 [0100] The below Table 6 shows the DCIR measurement of various cell samples
comprising electrode CE-4 as the cathode.
Table 6
Cell
number
Formation Cycle DCIR
[after subjecting
to formation
cycle; mΩ]
DCIR
[Total]
[Before rate
test; mΩ]
DCIR
[After
rate
test
mΩ]
Charge
(mAh)
Discharge
(mAh)
ICE%
1 25.69 23.34 90.85 5.07 4.76 5.61
2 25.86 23.51 90.92 4.80 4.63 5.40
3 25.62 23.32 91.01 5.39 5.27 5.97
4 25.98 23.68 91.16 4.38 4.20 5.29
5 25.89 23.56 90.98 4.55 4.39 5.21
6 25.97 23.72 91.34 4.06 3.88 4.94
10
31
[0101] The below Table 7 shows the DCIR measurement of various cell samples
comprising electrode CE-5 as the cathode.
Table 7
Cell
number
Formation Cycle DCIR
[after subjecting
to formation
cycle; mΩ]
DCIR
[Total]
[Before
rate test;
mΩ]
DCIR
[After
rate
test
mΩ]
Charge
(mAh)
Discharge
(mAh)
ICE%
1
26.49 23.72 89.55 5.35 6.54 7.98
2
25.79 23.46 90.94 6.78 6.49 7.28
3
25.97 23.54 90.64 5.79 5.54 6.51
4
25.91 23.58 90.99 4.85 4.78 5.86
5
25.82 23.42 90.69 5.89 5.27 5.97
6 25.97 23.72 91.34 4.06 3.88 4.94
5 [0102] The results showed that the cells comprising the electrode EA prepared by
the process 1 as disclosed in Example 1, exhibited improved electrochemical
performance in terms of the direct current internal resistance (DCIR). It was found
that the DCIR for the electrode EA, was lesser than 6 mΩ. In addition, the initial
coulombic efficiency (ICE) of the cell prepared using the electrode EA was found
10 to be 92% because of proper electronic networking and enhanced particle
connectivity as found in the SEM results. Furthermore, the cell comprising the
electrode EA showed a coulombic efficiency of 91% along with better
charge/discharge capacity of the cell. Meanwhile, the electrode prepared using the
comparative process 2 showed a DCIR of more than 7mΩ, and an ICE of 89%.
15 Further, it was observed that there was no change in DCIR value after subjecting
the battery/cell to a formation protocol or after nominal capacity measurement. This
indicated that the electrode comprising high conductive carbon content (of about
1.5%) had formed a stable, electronically conductive and homogenously distributed
electrode structure.
20 [0103] The cells comprising electrode EA as cathode (EA-1 to EA-6) exhibited
32
improved rate performance and there was only negligible increment in DCIR after
rate test as shown in the Table 2. Hence, it was concluded that there was an
improvement in the energy retention percentage from 90 to 94% when the cathode
was electrode EA of the present disclosure.
5 [0104] Therefore, the electrode EA having higher amount of conductive carbon
(~1.5%) ensured proper electronic networking throughout the electrode by enabling
enhanced networking among the active material particles and conductive carbon
particles.
[0105] Meanwhile, the other cells comprising comparative electrodes CE-1 to CE10 5 as the cathode, showed high DCIR before and after rate test. Furthermore, the
DCIR for some of the cells comprising these comparative electrodes as their
corresponding cathodes showed extremely high values of up to 9.89 mΩ. However,
the sample cells comprising electrode EA as the cathode showed a maximum DCIR
value of ~5.9 mΩ even after rate test. This showed that the disclosed process of the
15 present disclosure along with the disclosed ratios of conductive carbons (primary
and secondary) led to the enhanced conductivity and reduced internal resistance in
the electrode EA.
ADVANTAGES OF THE PRESENT DISCLOSURE:
20 [0106] The present disclosure provides a process for preparing battery electrodes
such as anodes and cathodes. The process of the present disclosure incurs less cost,
consumes less energy and are economically viable processes. The present
disclosure provides a process of preparing battery electrode which involves
stepwise sequential mixing to reduce the possibility of the carbon agglomeration
25 into the slurry which will confer the homogeneous electrical conductivity in the
electrodes throughout its length. The present disclosure further involves utilization
of optimum conductive carbon by with a keen consideration of morphology, and
aspect ratio of the conductive additives. Further, the amount of conducting additives
also improved the electronic conductivity along with the energy density of the cell.
30 The electrode prepared by the process of the present disclosure therefore exhibits
improved electrochemical efficiency. The process of the present disclosure is
33
suitable for preparing an anode as well as a cathode. Further, the electrochemical
cells prepared using the electrodes prepared by the process of the present disclosure
exhibits a very less through plane resistance of 0.44 Ohms.
34
I/We Claim:
1. A process for preparing an electrode, the process comprising:
a. mixing a primary conductive carbon with a binder solution to obtain a
pre-mixture;
5 b. blending a first part of an active material with the pre-mixture to obtain
a blend;
c. adding and stirring a first part of a secondary conductive carbon with the
blend to obtain a first mixture;
d. adding a second part of the active material with the first mixture to obtain
10 a second mixture;
e. mixing a second part of the secondary conductive carbon with the second
mixture, followed by high-speed mixing to obtain an electrode slurry;
and
f. processing of the electrode slurry to obtain the electrode,
15 wherein the primary conductive carbon and the secondary conductive
carbon are in a weight ratio range of 1:0.75 to 1:1.5; and
wherein the combined weight of the primary conductive carbon and the
secondary conductive carbon is in a range of 1 to 2%, with respect to the
total weight of the electrode.
20 2. The process as claimed in claim 1, wherein the primary conductive carbon is
in a weight range of 0.5 to 1%, with respect to the total weight of the
electrode; and the primary conductive carbon is selected from single walled
carbon nanotube (SWCNT), multiwalled carbon nanotube (MWCNT),
carbon nanofiber, vapour grown carbon nanofiber or combinations thereof.
25 3. The process as claimed in claim 1, wherein the first part of the secondary
conductive carbon and the second part of the secondary conductive carbon
are in a weight ratio range of 1:0.75 to 1:1.5.
4. The process as claimed in claim 1, wherein the first and the second part of the
secondary conductive carbon combinedly is in a weight range of 0.5 to 1%,
30 with respect to the total weight of the electrode; and the secondary conductive
carbon is selected from graphite, graphene, carbon black, acetylene black, or
combinations thereof.
35
5. The process as claimed in claim 1, wherein the binder solution is a mixture of
a binder with a solvent.
6. The process as claimed in claim 5, wherein the binder is in a weight range of
1 to 2%, with respect to total weight of the electrode;
5 the binder is selected from polyvinylidene fluoride (PVDF), polypropylene
carbonate (PPC), poly(vinylidene fluoride-hexafluoropropylene) (PVDFHFP), polyfluoroxy alkanes (PFA), polyvinyl fluoride (PVF), polyethylene
(PE), polyethylene vinyl acetate (PEVA), polyethylene glycol (PEG),
polyurethane (PU), polypropylene rubber (PPR), ethylene propylene rubber
10 (EPR), polyisobutylene (PIB), polyvinyl alcohol (PVA), phenoxy resin,
polyethylene terephthalate (PET), nylon, polymethyl methacrylate (PMMA),
polyvinyl chloride (PVC), polyphenylene sulphide (PPS), poly(3,4-
ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polystyrene
(PS), or combinations thereof; and
15 the solvent is selected from N-methyl pyrrolidone, dimethyl formamide,
dimethyl sulfoxide, ethylene carbonate, ethylene glycol, glycerol, or
combinations thereof.
7. The process as claimed in claim 1, wherein the first part of the active material
and the second part of the active material are in a weight ratio range of 1: 0.75
20 to 1: 1.5.
8. The process as claimed in claim 1, wherein the first and the second part of the
active material combinedly is in a weight range of 96 to 98% with respect to
total weight of the electrode; and the active material is selected from lithium
nickel manganese oxide (NMC), lithium cobalt oxide (LCO), lithium
25 manganese oxide (LMO), lithium iron phosphate (LFP), lithium yttrium iron
phosphate (LYP), lithium nickel manganese cobalt oxide, lithium nickel
cobalt aluminium oxide (NCA), lithium manganese phosphate (LiMnPO4),
lithium cobalt phosphate (LiCoPO4), lithium vanadium phosphate (LVP),
spinel type alkali metal transition metal oxides, alkali-transition metal oxides
30 (AMO2) oxides, or combinations thereof.
9. The process as claimed in claim 1, wherein mixing in step (a) is carried out at
a speed in a range of 200 to 800rpm for a time period ranging from 10 to 20
36
minutes.
10. The process as claimed in claim 1, wherein blending in step (b) is carried out
by stirring at a speed in a range of 800 to 1200 rpm, for a period in a range of
5 to 20 minutes.
5 11. The process as claimed in claim 1, wherein stirring in step (c) is carried out
at a speed in a range of 800 to 1200 rpm, for a period in a range of 5 to 20
minutes.
12. The process as claimed in claim 1, wherein step (d) comprises agitation at a
speed in a range of 800 to 1200 rpm, for a period in a range of 5 to 20 minutes.
10 13. The process as claimed in claim 1, wherein mixing in step (e) is carried out at
a speed in a range of 800 to 1200 rpm, for a period in a range of 5 to 20
minutes.
14. The process as claimed in claim 1, wherein the high-speed mixing in step (e)
is carried out at a speed in a range of 1600 to 2500 rpm for a period in a range
15 of 130 to 200 minutes.
15. The process as claimed in claim 1, wherein processing comprises coating the
electrode slurry on a substrate, drying, calendering, or combinations thereof.
16. The process as claimed in claim 15, wherein the substrate is a current collector
selected from aluminium foil, carbon coated copper aluminium foil, primer
20 coated aluminium foil, or glossy aluminium foil.
17. An electrode obtained by the process as claimed in claim 1, wherein the
electrode comprises:
a) an active material;
b) a binder;
25 c) a primary conductive carbon; and
d) a secondary conductive carbon,
wherein the primary conductive carbon and the secondary conductive
carbon are present in a weight ratio range of 1: 0.75 to 1: 1.5.
18. The electrode as claimed in claim 17, wherein the combined weight of the
30 primary conductive carbon and the secondary conductive carbon is in a range
of 1 to 2%, with respect to the total weight of the electrode.
19. The electrode as claimed in claim 17, wherein the electrode is a cathode, and
37
the cathode has a through plane resistance in a range of 0.2 to 0.5 Ohms.
20. An electrochemical cell comprising:
a. an anode;
b. a cathode comprising the electrode obtained by the process as claimed in
5 claim 1; and
c. an electrolyte.
21. The electrochemical cell as claimed in claim 20, wherein the anode is selected
from synthetic graphite, natural graphite, or silicon-graphite composite.
22. The electrochemical cell as claimed in claim 20, wherein the electrolyte
10 comprises a lithium salt selected from LiPF6, LiFSi, or LiTFSi; and a solvent
selected from diethylene carbonate, dimethyl carbonate, ethyl methyl
carbonate, vinyl carbonate, or combinations thereof.