A binder composite, an electrode and process thereof

Abstract

The present disclosure provides a binder composite, comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. The present disclosure further relates to an electrode composition and an electrochemical cell thereof.

Description

A BINDER COMPOSITE, AN ELECTRODE AND PROCESS THEREOFFIELD OF THE INVENTION

[0001] The present disclosure broadly relates to the field of batteries. Particularly, the present disclosure relates to a binder composite, an electrode comprising the binder composite, and a process for fabricating the electrode.BACKGROUND OF THE INVENTION

[0002] The demand for batteries is rapidly increasing due to their widespread use in various applications, including portable electronics, electric vehicles, and renewable energy systems. In particular, secondary batteries, such as lithium-ion batteries, have gained significant attention as a primary power source for the above- mentioned applications. Hence, a substantial amount of research is underway to enhance the conductivity and thereby cycle-life of existing secondary batteries by improving the process of preparation of the dry electrodes.

[0003] Dry electrodes are a type of electrode that is prepared without any solvents or liquid reagents, unlike traditional wet electrodes. Dry electrodes have increased durability, stability, convenience and reusability. Further, dry electrodes also have reduced risk of electric shocks, cost-effectiveness and compatibility in comparison to conventional wet electrodes due to the absence of organic solvents.

[0004] However, dry electrodes find it challenging to perform effectively at higher c-rates. Dry electrodes develop an internal electrical resistance during higher c- rates, which restricts their electrochemical performance at high temperatures. Further, during the electrochemical cycling, as the current flowing through the electrode increases, electrolytes are depleted or decomposed, reducing the availability of ions for conduction. This depletion can also cause a significant decrease in the ionic conductivity of the electrodes. Furthermore, as the current increases, the electrode-electrolyte interface becomes detrimentally affected due to electrochemical reactions such as corrosion or oxidation or development of concentration gradients within the electrolyte, further decreasing the conductivity.

[0005] Generally, dry electrodes comprise an active material coated with conductive carbon. This carbon coated active material is then mixed with binders to achieve an electrode film with satisfactory tensile strength and mechanicalintegrity. However, binders that are generally polymers, are electrically insulating in nature. Hence, the binders form an insulating layer over the electrode active material which prevents the conduction of electrons during charge-discharge cycle and thereby inherently contributes to the reduction in the cell performance. The existing techniques to enhance the conductivity of the dry electrode include employment of additives, increasing the conductive carbon content and decreasing the binder content. However, these strategies have failed in terms of mechanical integrity of the electrode film or in aspects of offering a better electrochemical performance at higher c-rates.

[0006] Therefore, there is a need in the art to develop high functioning polymers or polymer composites as binders that have high mechanical strength and merely affects the total conductivity of the electrodes when cycled at higher c-rates.SUMMARY OF THE INVENTION

[0007] In the first aspect of the present disclosure, there is provided a binder composite, comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

[0008] In a second aspect of the present disclosure, there is provided a process of preparation of the binder composite as disclosed herein, the process comprising: mixing the adhesive binder, the fibrillating binder, the primary carbon and optionally a secondary carbon to obtain the binder composite.

[0009] In a third aspect of the present disclosure, there is provided an electrode composition comprising: (a) 95.5 to 97% by weight of an active material; (b) 1 to 1.5% by weight of at least two conductive carbons; and (c) 1 to 3% by weight of the binder composite as disclosed herein; wherein the at least two conductive carbons comprises a first conductive carbon, and a second conductive carbon in a weight ratio range of 1:0.1 to 2:0.5.

[0010] In a fourth aspect of the present disclosure, there is provided a process for preparing the electrode composition as disclosed herein, the process comprising: (a) blending the active material with the primary carbon, the secondary carbon and the binder composite as disclosed herein to obtain a first mixture; and (b) high shear mixing the first mixture followed by cooling to obtain the electrode composition.

[0011] In a fifth aspect of the present disclosure, there is provided an electrochemical cell comprising: (a) a cathode; (b) an anode comprising the electrode as disclosed herein, coated on a current collector; and (c) an electrolyte.

[0012] These and other features, aspects, and advantages of the present subject 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.BRIEF DESCRIPTION OF THE FIGURES

[0013] 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.

[0014] Figure 1 depicts the peel strength of the binder composite with varying weight ratio of the adhesive binder polyvinylidene fluoride (PVDF) and the fibrillating binder polytetrafluoroethylene (PTFE), in accordance with an embodiment of the present disclosure.

[0015] Figure 2 depicts the tensile strength of the binder composite with varying weight% of primary carbon (CC content), in accordance with an embodiment of the present disclosure.

[0016] Figure 3 depicts the field emission scanning electron microscopy (FESEM) image of the Cathode-IIa comprising a binder composite BC-2 having more than 50% w / w of carbon (primary and secondary carbons), in accordance with an embodiment of the present disclosure.

[0017] Figure 4 depicts the (i) zoomed out and (ii) zoomed in surface FESEM images of the cathodes (A) I and (B) II, in accordance with an embodiment of the present disclosure.

[0018] Figure 5 depicts the charge-discharge cycle data of Cathode- I and II, in accordance with an embodiment of the present disclosure.

[0019] Figure 6 depicts the electrochemical analysis exhibited by the half-cell comprising the Cathode-II, in accordance with an embodiment of the present disclosure.

[0020] Figure 7 depicts the graphical representation of state of health (SOH) of (i) Cathode- I and II; and (ii) Cathode-II at 25°C and 45°C, in accordance with an embodiment of the present disclosure.

[0021] Figure 8 depicts the capacity measurement of the Cathode- I and II at different c-rates, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION OF THE INVENTION

[0022] 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

[0023] 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.

[0024] 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.

[0025] 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”.

[0026] 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.

[0027] The term “including” is used to mean “including but not limited to”. “Including” and “including but not limited to” are used interchangeably.

[0028] The term “binder composite” refers to a material that is prepared by combining a binder with a conductive additive. In an aspect of the present disclosure, binder composite comprises an adhesive binder and a fibrillating biner along with a primary carbon.

[0029] The term “primary carbon” refers to a conducting additive material that is present in the binder composite to improve its electrical conductivity properties by creating an electrical network. In an aspect of the present disclosure, the primary carbon has a surface area in a range of 1000 to 2000 m2 / g and is selected from nonstructured carbon black, high surface area carbon nanofiber, single walled carbon nanotube, or combinations thereof.

[0030] The term “secondary carbon” refers to the conducting additive material that is optionally present in the binder composite to enhance the electrical conductivity. In an aspect of the present disclosure, secondary carbon has a surface area in a range of 10 to 80 m2 / g and is selected from synthetic graphite, structured carbon black, low surface area carbon nanofiber, graphene, or combinations thereof.

[0031] The term “adhesive binder” refers to a type of binder that is used to bond two or more materials together, typically by forming a strong chemical bond or physical interactions between the surfaces of the materials. In an aspect of the present disclosure, the adhesive binder is selected from polyethylene oxide, polyvinylidene fluoride (PVDF), vinylidene fluoride, polyvinylidene fluoride-co- hexafluoropropylene (PVDF-HFP), polyacrylic acid (PAA), high molecular weight polyethylene (HMWPE) or combinations thereof.

[0032] The term “fibrillating binder” refers to a polymeric substance that undergoes a process called fibrillation, where the particles transform into new structures, creating a network of fibers that can improve the mechanical properties of a composite material. In an aspect of the present disclosure, the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene vinyl ether (FEVE), or combinations thereof.

[0033] The term “resistance” refers to the measure of opposition exhibited by a material against the flow of electric current, typically measured in ohm (Q). The term “resistance” and “electrical resistance” refers to same and shall be used interchangeably. Lower resistance implies higher conductance of the material. In an aspect of the present disclosure, the binder composite exhibits a resistance in a range of 0.1 to 0.7 Q cm.

[0034] The term “peel strength” refers to the measure of the force required to peel or delaminate a layer or material from another layer or substrate, typically measured in units of force per unit length. It determines the bond strength and adhesion between two layers or materials. A higher peel strength indicates a stronger bond between the layers. In an aspect of the present disclosure, a film of the binder composite exhibits a peel strength in a range of 4 to 6 N / 25 mm.

[0035] The term “tensile strength” refers to the maximum stress a material can withstand before it fails or breaks, typically measured in units of force per unit area, such as Pascals (Pa) or Mega Pascals (MPa). It is the ability of a material to withstand an external force that tries to pull it apart, and a higher tensile strength indicates a material that is more resistant to stretching or breaking under tension. In an aspect of the present disclosure, a film of the binder composite exhibits a tensile strength in a range of 7 to 20 MPa.

[0036] The term “tip speed” refers to the speed at which the tip of a mixing tool, such as a blade or impeller, moves through the mixture being processed. A higher tip speed typically results in a more intense mixing action.

[0037] 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 isselected from synthetic graphite, natural graphite, silicon, or combinations thereof. In an aspect of the present disclosure, the active material is selected from lithium nickel manganese cobalt oxide, nickel cobalt aluminium oxide, lithium iron phosphate, lithium iron manganese phosphate, or combinations thereof.

[0038] 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 include a lithium and a solvent, wherein the lithium salt is selected from LiPFe, Lithium bis(fluorosulfonyl)imide (LiFSI), Lithium bis (trifluoromethanesulfonyl)imide (LiTFSI), Lithium difluoro (oxalato)borate (LiDFOB), or combinations thereof; and the solvent is selected from ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, vinylene carbonate, or combinations thereof.

[0039] 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 first conductive carbon and a second conductive carbon.

[0040] The term “discharge capacity” refers to the maximum amount of electric charge that an electrode can release or deliver during a single discharge cycle. It is a measure of the electrode's ability to provide electrical energy and is typically expressed in terms of the capacity per unit area (e.g., mAh / cm2). In an aspect of the present disclosure, discharge capacity of the electrode composition is in a range of 90 to 95%.

[0041] The term “state of health” or “SOH” refers to the measure of an electrode’s ability to deliver its expected performance and capacity over time. It is a measure of the degradation or deterioration of the electrode's electrochemical performance. The electrochemical performance of an electrode is directly dependent on its material properties, such as its surface area, porosity, and electrochemical reactivity, which vary due to factors such as electrochemical cycling. In an aspect of the present disclosure, the state of health of the electrode composition is in arange of 96 to 99%. Higher the state of health, higher is the electrochemical performance and stability of the electrode or electrode composition.

[0042] The term “current collector” refers to the component introduced in a cell to conduct and bridge the flow of electrons between the active material and the external battery terminals. In an aspect of the present disclosure, there is provided a cathode comprising the electrode composition as disclosed herein, coated on a current collector. The current collector is selected from an anodic current collector or a cathodic current collector. The anodic current collector is selected from copper foil, copper sheet, copper bar or glossy copper foil. The cathodic current collector is selected from aluminium foil, aluminium sheet, glossy aluminium sheet, or carbon pre-coated aluminium sheet.

[0043] The term “initial coulombic efficiency” denoted as ICE, refers to the efficiency of an electrochemical cell for the first charge-discharge cycle. In an aspect of the present disclosure, the electrode composition exhibits an initial coulombic efficiency (ICE) in a range of 90 to 95%.

[0044] 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, blending carried out for a period in a range of 20 to 40 minutes should be interpreted to include not only the explicitly recited limits of 20 to 40 minutes but also to include sub-ranges, such as 28 to 38 minutes, 20 to 25 minutes and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 27.5 minutes, 30 minutes, 35 minutes, and 39.5 minutes.

[0045] 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.

[0046] 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.

[0047] As discussed in the background, there is a dire need in the art to develop an efficient dry electrode, which exhibits high conductivity, and better electrochemical performance (in aspects of improved discharge capacity, initial coulombic efficiency, and capacity retention), without compromising mechanical integrity (in terms of peel strength and tensile strength). The existing dry cathodes exhibit reduced conductivity at higher c-rates. Higher c-rates draws more current from the cell, thereby increases the internal resistance of electrodes and heat production. Thus, operating batteries at higher c-rates negatively affect their chemical reactions, potentially reducing the energy conversion efficiency and thereby its specific capacity. The conductivity of electrodes can be enhanced by increasing the weight percentage of conductive carbon and reducing the amount of binder, owing to the insulating behavior of the binder. However, the addition of conductive carbon for increasing conductivity beyond a certain value, resulted in agglomeration of conductive carbons. In addition, reducing the binder content adversely affects the film stability and mechanical integrity of the electrode with respect to adhesion with current collector. All of these resulted in increasing internal resistance and lowering electrochemical performance. To achieve the objective of higher conductivity and reduced internal resistance at high current without lowering the structural integrity of the electrode film, the present disclosure provides a binder composite comprising high surface area conductive carbon and an adhesive binder, and a fibrillating binder, which enhances conductivity by reducing the internal resistance and retains peel strength. The present disclosure provides a binder composite comprising a primary conductive carbon having high surface area, an adhesive binder and a fibrillating binder, wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. Furthermore, the present disclosure also employs a secondary conductive carbon having lower surface area along in the bindercomposite. The present disclosure is also directed to the development of innovative fabrication methods for the production of highly conducting electrodes yet having mechanical strength, which are crucial in the manufacturing of high-performance batteries.

[0048] Accordingly, the present disclosure provides a binder composite, comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. In another embodiment of the present disclosure, the adhesive binder and the fibrillating binder are in a weight ratio range of 3.5:6.5 to 5:5. In yet another embodiment of the present disclosure, the adhesive binder and the fibrillating binder are in a weight ratio range of 4:6 to 5:5.

[0049] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. In another embodiment of the present disclosure, the primary carbon has a surface area in a range of 1000 to 1500 m2 / g. In yet another embodiment of the present disclosure, the primary carbon has a surface area in a range of 1000 to 1400 m2 / g.

[0050] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite may further include secondary carbon, and wherein the combined weight of the primary carbon and optional secondary carbon is in a range of 10 to 55%, with respect to the total weight of the binder composite.

[0051] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a ratio range of 10:90 to 55:45. In another embodiment of the present disclosure, weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a ratio range of 12:88 to 40:60. In yet another embodiment of the presentdisclosure, weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a ratio range of 15:85 to 20:80. In still another embodiment of the present disclosure, weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a ratio range of 15:85 to 18:82.

[0052] In an embodiment of the present disclosure, there is provided a binder composite comprises comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. In another embodiment of the present disclosure, there is provided a binder composite comprises comprising: (a) 10 to 53% by weight of a primary carbon; (b) 30 to 43% by weight of an adhesive binder; and (c) 30 to 43% by weight of a fibrillating binder. In yet another embodiment of the present disclosure, there is provided a binder composite comprises comprising: (a) 12 to 20% by weight of a primary carbon; (b) 38 to 43% by weight of an adhesive binder; and (c) 38 to 43% by weight of a fibrillating binder. In still another embodiment of the present disclosure, there is provided a binder composite comprises comprising: (a) 15 to 20% by weight of a primary carbon; (b) 39 to 41% by weight of an adhesive binder; and (c) 39 to 41% by weight of a fibrillating binder.

[0053] In an embodiment of the present disclosure, there is provided a binder composite comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a weight ratio range of 10:90 to 55:45; and the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

[0054] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the primary carbon is selected from nonstructured carbon black (such as Ketjen black, Vulcan black), high surface area carbon nanofiber, single walled carbon nanotube (SWCNT) or combinationsthereof. In another embodiment of the present disclosure, the primary carbon is nonstructured carbon black (Ketjen Black).

[0055] In an embodiment of the present disclosure, there is provided a binder composite, comprising: (a) 10 to 55% by weight of a primary carbon selected from non- structured carbon black, high surface area carbon nanofiber, single walled carbon nanotube (SWCNT) or combinations thereof, and having surface area in a range of 500 to 2000 m2 / g; (b) 22 to 45% by weight of an adhesive binder; and (c) 22 to 45% by weight of a fibrillating binder; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

[0056] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene vinyl ether (FEVE), or combinations thereof; and the adhesive binder is selected from polyethylene oxide, polyvinylidene fluoride (PVDF), vinylidene fluoride, polyvinylidene fluoride-co- hexafluoropropylene (PVDF-HFP), polyacrylic acid (PAA), high molecular weight polyethylene (HMWPE) or combinations thereof. In another embodiment of the present disclosure, the fibrillating binder is polytetrafluoroethylene (PTFE) and the adhesive binder is poly vinylidene fluoride (PVDF).

[0057] In an embodiment of the present disclosure, there is provided a binder composite, comprising: (a) 10 to 55% by weight of a primary carbon selected from non- structured carbon black, high surface area carbon nanofiber, single walled carbon nanotube (SWCNT) or combinations thereof, and having surface area in a range of 500 to 2000 m2 / g; (b) 22 to 45% by weight of an adhesive binder selected from polyethylene oxide, polyvinylidene fluoride (PVDF), vinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyacrylic acid (PAA), high molecular weight polyethylene (HMWPE) or combinations thereof; and (c) 22 to 45% by weight of a fibrillating binder selected from polytetrafluoroethylene (PTFE), fluoroethylene vinyl ether (FEVE), or combinations thereof; wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

[0058] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the adhesive binder has particle size in a range of 5 to 10 micrometer; and the fibrillating binder has particle size in a range of 200 to 500 micrometer.

[0059] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite comprises 1 to 10% by weight of a secondary carbon having a surface area in a range of 10 to 80 m2 / g; and the secondary carbon is selected from synthetic graphite, structured carbon black, low surface area carbon nano fiber, graphene or combinations thereof. In another embodiment of the present disclosure, the binder composite comprises 2 to 8% by weight of a secondary carbon having a surface area in a range of 10 to 80 m2 / g; and the secondary carbon is selected from synthetic graphite, graphene or combinations thereof. In yet another embodiment of the present disclosure, the binder composite comprises 3 to 6% by weight of a secondary carbon having a surface area in a range of 10 to 30 m2 / g; and the secondary carbon is synthetic graphite (KS6L).

[0060] In an embodiment of the present disclosure, there is provided a binder composite comprising: (a) 10 to 55% by weight of a primary carbon selected from non- structured carbon black, high surface area carbon nanofiber, single walled carbon nanotube (SWCNT) or combinations thereof and having a surface area in a range of 1000 to 2000 m2 / g; (b) 22 to 45% by weight of an adhesive binder selected from polyethylene oxide, polyvinylidene fluoride (PVDF), vinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyacrylic acid (PAA), high molecular weight polyethylene (HMWPE) or combinations thereof having particle size in a range of 5 to 10 micrometer; and (c) 22 to 45% by weight of a fibrillating binder selected from polytetrafluoroethylene (PTFE), fluoroethylene vinyl ether (FEVE), or combinations thereof, and (d) 1 to 10% by weight of a secondary carbon having a surface area in a range of 10 to 80 m2 / g; and the secondary carbon is selected from synthetic graphite, structured carbon black (such as Super P), low surface area carbon nanofiber, or combinations thereof, and having a particle size in a range of 500 nanometer to 50 micrometer; and whereinthe adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

[0061] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite comprises 1 to 10% by weight of a secondary carbon having a surface area in a range of 10 to 80 m2 / g. In another embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite comprises 3 to 9% by weight of a secondary carbon. In yet another embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite comprises 4 to 5% by weight of a secondary carbon.

[0062] In an embodiment of the present disclosure, there is provided a binder composite comprising: (a) 10 to 55% by weight of a primary carbon; (b) 22 to 45% by weight of an adhesive binder; (c) 22 to 45% by weight of a fibrillating binder; and (d) 1 to 10 % by weight of a secondary binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5. In another embodiment of the present disclosure, the binder composite comprises: (a) 12 to 50% by weight of a primary carbon; (b) 30 to 45% by weight of an adhesive binder; (c) 30 to 45% by weight of a fibrillating binder; and (d) 2 to 8% by weight of a secondary carbon. In yet another embodiment of the present disclosure, the binder composite comprises: (a) 14 to 16% by weight of a primary carbon; (b) 38 to 42% by weight of an adhesive binder; (c) 38 to 42% by weight of a fibrillating binder; and (d) 3 to 5% by weight of a secondary carbon.

[0063] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite is in the form of a powder, a film, a paste or a solid. In another embodiment of the present disclosure, the binder composite is in the form of a film.

[0064] In an embodiment of the present disclosure, there is provided a binder composite as disclosed herein, wherein the binder composite is calendered to obtain a binder composite film; the binder composite-film exhibits a resistance in a range of 0.1 to 0.7 Q; a peel strength in a range of 4 to 6 N / 25 mm; and a tensile strengthin a range of 7 to 20 MPa. In another embodiment of the present disclosure, the binder composite film exhibits a resistance in a range of 0.2 to 0.65 > cm; a peel strength in a range of 4.1 to 5.9 N / 25 mm; and a tensile strength in a range of 10 to 16 MPa.

[0065] In an embodiment of the present disclosure, there is provided a process of preparation of the binder composite as disclosed herein, wherein the process comprising: mixing the adhesive binder, the fibrillating binder, the primary carbon and optionally a secondary carbon to obtain the binder composite.

[0066] In an embodiment of the present disclosure, there is provided a process of preparation of the binder composite as disclosed herein, wherein the process comprising: mixing the adhesive binder, the fibrillating binder, the primary carbon and optionally a secondary carbon, followed by calendering to obtain the binder composite.

[0067] In an embodiment of the present disclosure, there is provided a process for the preparation of binder composite as disclosed herein, wherein the mixing is carried out at a temperature in a range of 10 to 20°C, and at a tip speed in a range of 15 to 21 m / s. In another embodiment of the present disclosure, mixing is carried out at a temperature in a range of 12 to 19°C, and at a tip speed in a range of 15 to 18 m / s. In yet another embodiment of the present disclosure, mixing is carried out at a temperature in a range of 14 to 16°C, and at a tip speed in a range of 15.2 to 15.5 m / s.

[0068] In an embodiment of the present disclosure, there is provided a process of preparation of the binder composite, the process comprising: mixing the adhesive binder, the fibrillating binder, the primary carbon and optionally a secondary carbon at a temperature in a range of 10 to 20°C, and at a tip speed in a range of 15 to 21 m / s to obtain the binder composite.

[0069] In an embodiment of the present disclosure, there is provided an electrode composition comprising: (a) 95.5 to 97% by weight of an active material; (b) 1 to 1.5% by weight of at least two conductive carbons; and (c) 1 to 3% by weight of the binder composite as disclosed herein, wherein the at least two conductive carbons comprises a first conductive carbon, and a second conductive carbon in aweight ratio range of 1:0.1 to 2:0.5. In another embodiment of the present disclosure, the electrode composition comprises: (a) 96 to 97% by weight of an active material; (b) 1.2 to 1.5% by weight of at least two conductive carbons; and (c) 2 to 3% by weight of the binder composite as disclosed herein, wherein the at least two conductive carbons comprises a first conductive carbon, and a second conductive carbon in a weight ratio range of 1:0.1 to 1.5:0.5. In yet another embodiment of the present disclosure, the electrode composition comprises: (a) 96 to 96.5% by weight of an active material; (b) 1.2 to 1.4% by weight of at least two conductive carbons; and (c) 2.4 to 2.6% by weight of the binder composite as disclosed herein, wherein the at least two conductive carbons comprises a first conductive carbon, and a second conductive carbon in a weight ratio range of 1:0.1 to 1:0.5.

[0070] In an embodiment of the present disclosure, there is provided an electrode composition as disclosed herein, wherein the combined weight of primary carbon, optionally secondary carbon and at least two conductive carbons is in a weight range of 1.5 to 2%, with respect to total weight of the electrode composition.

[0071] In an embodiment of the present disclosure, there is provided an electrode composition as disclosed herein, wherein the active material is selected from lithium nickel manganese cobalt oxide, nickel cobalt aluminium oxide, lithium iron phosphate, lithium iron manganese phosphate, or combinations thereof; the first conductive carbon is selected from non-structured carbon black, carbon nanofiber, carbon nanotube, or combinations thereof; and the second conductive carbon is selected from synthetic graphite, structured carbon black, graphene, graphitic carbon, or combinations thereof.

[0072] In an embodiment of the present disclosure, there is provided an electrode composition comprising: (a) 95.5 to 97% by weight of an active material selected from synthetic graphite, natural graphite, silicon, or combinations thereof; (b) 1 to 1.5% by weight of at least two conductive carbons comprising a first conductive carbon selected from non-structured carbon black, carbon nano fiber or combinations thereof, and a second conductive carbon selected from synthetic graphite, structured carbon black, or combinations thereof, in a weight ratio rangeof 1:0.1 to 1:0.5; and (c) 1 to 3% by weight of the binder composite as disclosed herein.

[0073] In an embodiment of the present disclosure, there is provided an electrode composition as disclosed herein, wherein the first conductive carbon has a surface area in a range of 500 to 2000 m2 / g; and the second conductive carbon has a surface area in a range of 10 to 80 m2 / g. In another embodiment of the present disclosure, the first conductive carbon has a surface area in a range of 600 to 1800 m2 / g; and the second conductive carbon has a surface area in a range of 12 to 75m2 / g. In yet another embodiment of the present disclosure, there is provided the first conductive carbon has a surface area in a range of 800 to 1500 m2 / g; and the second conductive carbon has a surface area in a range of 15 to 65 m2 / g.

[0074] In an embodiment of the present disclosure, there is provided an electrode composition as disclosed herein, wherein the electrode composition exhibits an initial coulombic efficiency (ICE) in a range of 90 to 95% and a state of health of 96 to 99.9%. In another embodiment of the present disclosure, wherein the electrode composition exhibits an initial coulombic efficiency (ICE) in a range of 92 to 94% and a state of health of 97 to 99.5%, for up to 50 cycles within a temperature range of 25 to 45°C.

[0075] In an embodiment of the present disclosure, there is provided an electrode composition as disclosed herein, wherein the electrode composition is made into film and the film exhibits a peel strength in a range of 1.5 to 6 N / 25 mm; and a resistance in a range of 0.1 to 0.5 Q. In another embodiment of the present disclosure, the electrode composition film exhibits a peel strength in a range of 1.52 to 3 N / 25mm; and a resistance in a range of 0.25 to 0.4 Q.

[0076] In an embodiment of the present disclosure, there is provided a process for preparing the electrode composition, the process comprising: (a) blending the active material with the primary carbon, the secondary carbon and the binder composite as disclosed herein, to obtain a first mixture; and (b) high shear mixing the first mixture followed by cooling to obtain the electrode composition.

[0077] In an embodiment of the present disclosure, there is provided a process for preparing the electrode composition as disclosed herein, wherein the blending iscarried out at a tip speed in a range of 15 to 21 m / s, for a period in a range of 20 to 40 mins, and at a temperature in a range of 10 to 25 °C. In another embodiment of the present disclosure, blending is carried out at a tip speed in a range of 15 to 16 m / s, for a period in a range of 25 to 35 mins, and at a temperature in a range of 15 to 20 °C.

[0078] In an embodiment of the present disclosure, there is provided a process for preparing the electrode composition as disclosed herein, wherein the high shear mixing is carried out at a speed in a range of 25 to 36 m / s at a temperature in a range of 60 to 80°C; and cooling is carried out by mixing at a speed in a range of 5 to 10 m / s, until reaching a temperature in a range of 0 to 19°C. In another embodiment of the present disclosure, the high shear mixing is carried out at a speed in a range of 28 to 32 m / s at a temperature in a range of 65 to 75°C; and cooling is carried out by mixing at a speed in a range of 6 to 8 m / s, until reaching a temperature in a range of 5 to 15°C.

[0079] In an embodiment of the present disclosure, there is provided a process for preparing the electrode composition, the process comprising: (a) blending the active material with the primary carbon, the secondary carbon and the binder composite at a tip speed in a range of 15 to 21 m / s, for a period in a range of 20 to 40 mins, and at a temperature in a range of 10 to 25 °C to obtain a first mixture; and (b) high shear mixing the first mixture at a speed in a range of 25 to 36 m / s and at a temperature in a range of 60 to 80°C, followed by cooling at a speed in a range of 5 to 10 m / s, until reaching a temperature in a range of 0 to 19°C, to obtain the electrode composition.

[0080] In an embodiment of the present disclosure, there is provided a process for preparing the electrode composition, wherein the electrode composition has a particle size in a range of 8 to 12 micrometer. In another embodiment of the present disclosure, the electrode composition has a particle size in a range of 10 to 11.8 micrometer.

[0081] In an embodiment of the present disclosure, there is provided a cathode comprising the electrode composition comprising: (a) 95.5 to 97% by weight of an active material; (b) 1 to 1.5% by weight of at least two conductive carbons; and (c)1 to 3% by weight of the binder composite as disclosed herein, wherein the at least two conductive carbons comprises a first conductive carbon, and a second conductive carbon in a weight ratio range of 1:0.1 to 2:0.5.

[0082] In an embodiment of the present disclosure, there is provided a cathode comprising the electrode composition as disclosed herein.

[0083] In an embodiment of the present disclosure, there is provided a cathode comprising the electrode composition as disclosed herein, coated on a current collector.

[0084] In an embodiment of the present disclosure, there is provided an electrochemical cell comprising: (a) an anode; (b) a cathode comprising the electrode composition as disclosed herein, coated on a current collector; and (c) an electrolyte.

[0085] In an embodiment of the present disclosure, there is provided an electrochemical cell comprising: (a) an anode; (b) a cathode comprising the electrode composition as disclosed herein, coated on a current collector selected from aluminium foil, aluminium sheet, glossy aluminium sheet, or carbon precoated aluminium sheet; and (c) an electrolyte.

[0086] In an embodiment of the present disclosure, there is provided an electrochemical cell comprising: (a) a cathode; (b) an anode comprising the electrode composition as disclosed herein coated on a current collector selected from copper foil, copper sheet, copper bar or glossy copper foil; and (c) an electrolyte.

[0087] In an embodiment of the present disclosure, there is provided a use of the electrode obtained by the process disclosed herein as an anode or a cathode in an electrochemical cell.

[0088] 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.

[0089] Although the subject matter has been described in considerable detail with reference to certain examples and implementations thereof, other implementations are possible.EXAMPLES

[0090] The disclosure will now be illustrated with following examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar to 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

[0091] The various chemicals and solvents used in the present disclosure are as follows:Cathode active material nickel manganese cobalt (NMC811) having particle size of 5 to 15 micrometer was procured from Easpring.Primary carbon and First conductive carbon- Ketjen black (non- structured carbon black; BET surface area in a range of 1200 to 1600 m2 / g and particle size of 0.5 pm was procured from Nouryon.Secondary carbon and second conductive carbon: KS6L (synthetic graphite; BET surface area in a range of 10 to 80 m2 / g; particle size of 4 micrometer) was procured from Imerys.Adhesive binder: polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) was procured from Arkema having particle size of 5-10 micrometer.Fibrillating Binder: polytetrafluoroethylene (PTFE) of particle size of 350-550 micrometer was procured commercially.Pre-coated aluminium Current collector was procured from BlueGlow Nano.EXAMPLE 1(a) Preparation of the Binder composite

[0092] The present example explains the process of preparing the binder composite.

[0093] A binder composite was prepared by mixing 40% by weight of polyvinylidene fluoride copolymer (PVDF-HFP) (adhesive binder) and 40% by weight of polytetrafluoroethylene (PTFE) (fibrillating binder) along with 15.2% by weight of Ketjen black (primary carbon) at a stirring speed of 15.32 m / s for 15 minutes at a temperature less than 20°C. Further, 4.8% of KS6L (secondary carbon) was added to the above mixture and was mixed at a speed of 15.32 m / s for 15 minutes at a temperature less than 20°C to obtain a binder composite BC-1 (PVDF- HFP and PTFE are in a weight ratio of 1: 1 (equivalent 5:5); and weight of Ketjen black and the combined weight of the PVDF-HFP and PTFE are in a ratio of 16: 84).

[0094] For comparative purposes, a binder composite BC-2 was prepared by the process as explained above with 20 % of PVDF-HFP (adhesive binder) and 20 % of PTFE (fibrillating binder) along with 60 % of Ketjen black and KS6L (structured carbon black; primary carbon and secondary carbon). In BC-2, PVDF-HFP and PTFE were in a weight ratio of 1: 1 (equivalent 5:5); and weight of Ketjen black and the combined weight of the PVDF-HFP and PTFE were in a ratio of 60:40). The BC-2 had a total carbon content (primary carbon and secondary carbon) to be more than the disclosed range of 10 to 55%.(b) Characterization of the Binder composite of the present disclosure

[0095] The binder composite BC-1 was formed into a film by calendering and laminating on an aluminium current collector to obtain a binder composite film BCF-1. The calendering and lamination parameters are provided below:

[0096] Calendering was carried out by passing the binder composite through a pair of rollers about 4 times with roller gaps were maintained at 300 micrometer, 200 micrometer, and 100 micrometer at each pass, at a roll temperature of 150 °C, at a shear % of 150%, 66%, 145%, and 70% at each pass. The binder composite was further laminated at a force of 25 kN at a rate of 0.4 m per minute.

[0097] This binder composite film BCF-1 was analysed for its peel strength analysis, resistance and tensile strength.Peel strength:

[0098] The peel strength of the binder composite film BCF-1 prepared by the process as explained above was measured.

[0099] Peel strength analysis is a conventional analysis technique to measure the adhesion strength of a film upon the substrates of electrodes. For the test, a doublesided adhesive tape was first stuck onto the movable pull-off table. The binder composite to be tested was then glued to the adhesive tape. Subsequently, one of the two connected (glued) components was attached to the load cell using a tension clamp, which was integrated in the movable measuring arm of the testing device. During the test, the measuring arm moved upwards, separating the two materials adhering to each other at an angle of 90°. The congruent movement of the table maintained the 90° angle during the measurement. The pull-off speed was varied. The pull-off force standardized to the width of the test strip is called peel strength and is usually given in N / mm. After measuring and averaging the load required to peel the specimen, the peel strength was derived by dividing the average load by the bond line's unit width.

[0100] The peel strength of BCF-1 was measured by varying the weight ratio of adhesive binder (PVDF) and fibrillating binder (PTFE), while the carbon content (primary and secondary carbon) was fixed at 15% by weight of the binder composite (Figure 1). It was observed that the peel strength was found to be maximum (~6 N / 25mm), when the PVDF-HFP: PTFE weight ratio was 5:5.The desired peel strength value of (~4 to 7 N / 25mm) was obtained when the PVDF- HFP: PTFE ratios were in a range of 3:7 to 5:5.

[0101] It was observed that when the weight ratios of PVDF and PTFE were outside the disclosed range, the peel strength reduced considerably.Resistance:

[0102] The resistance of the binder composite film BCF-1 was measured with respect to the carbon (primary and secondary carbon) content and surface area of the carbon. The Table 1 below shows the variation of resistance in binder composite when the carbon with varying surface area was employed in varying weight ranges.Table 1

[0103] From Table 1, it was observed that BCF-1 with a carbon having a high surface area of more than 1000 m2 / g (such as Ketjen black having 1400 m2 / g) used in a weight range of 10 to 50% as primary carbon, exhibited low resistance values in a range of 0.1 to 0.5 Q, when it was employed in the weight range of 10 to 50 %, in a binder composite.Tensile strength:

[0104] Tensile strength analysis was performed for the BCF-1 prepared by the process as explained above. The tensile strength was measured with respect to the carbon (primary and secondary carbon) content in the binder composite, as depicted in Figure 2. The BCF-1 and other films having varying carbon content were fixed in the fixtures and the load was applied with cross-section speed of 12.5mm / min. Tensile strength was plotted for different films varying in content of primary and secondary carbons to observe that the tensile strength values of the BCF-1 havingcarbon content of 15 to 50% was desirably in a range of 7 to 20 MPa. When the carbon content was increased beyond 50%, tensile strength of the binder composite film was observed to drop considerably. However, when the content of primary and secondary carbons was reduced below 10%, the conductivity of the binder composite film was observed to be reduced.EXAMPLE 2Process of preparation of the Electrode composition

[0105] The present example explains the process of preparing the electrode composition.(a) Process of preparation of Cathode-I

[0106] For the purpose of the present disclosure, Cathode-I was prepared without using the binder composite of the present disclosure.

[0107] For preparing a cathode (Cathode-I), 96.2% by weight of layered lithium nickel manganese cobalt oxide NMC811 (active material, AM, having an average particle size of 10 micrometer), was mixed with 1% by weight of Ketjen black (nonstructured carbon black; first conductive carbon), and 0.3% by weight of KS6L (synthetic graphite; second conductive carbon) at a speed of 30.63 m / s for 120 minutes at a temperature of 15°C to obtain a first mixture. To the first mixture, 1% by weight of PVDF-HFP copolymer (binder) was added and blended at a tip speed of 15.32 m / s at a temperature less than 20°C for 15 min. A polytetrafluoroethylene (binder) of weight of 1.5% was added to the resulting blend and blended at a tip speed of 15.32 m / s for 15 min at a temperature less than 19°C to obtain a second mixture. The homogenously blended second mixture was then high shear mixed using a Zeppelin high intensity mixer at a tip speed of 3000 rpm until the temperature reached 70°C. The resulting mixture was then cooled to a temperature less than 19°C at a tip speed of 600rpm to obtain a dry cathode composition (electrode composition) DCC-I.

[0108] The dry cathode composition DCC-I was then calendared to obtain a cathode film-I. The cathode film-I was then laminated upon a carbon pre-coated aluminium current collector to obtain Cathode-I.(b) Process of preparation of Cathode-II

[0109] For the purpose of the present disclosure, Cathode-II was prepared using the binder composite BC-1 of the present disclosure.

[0110] For preparing a cathode (Cathode-II), 96.2% by weight of layered lithium nickel manganese cobalt oxide NMC811 (active material, AM, having an average particle size of 10 micrometer), was mixed with 1% by weight of Ketjen black (first conductive carbon), and 0.3% by weight of KS6L (second conductive carbon) at a speed of 30.63 m / s for 75 minutes at a temperature less than 25°C to obtain a premixture. To the pre-mixture, 2.5% by weight of binder composite BC-1 was added, followed by mixing at a speed of 15.32 m / s for 15 mins at a temperature of 15°C to obtain a first mixture. The homogenously blended first mixture was then high shear mixed using a Zeppelin high intensity mixer at a tip speed of 30.63 m / s until the temperature reached 70°C. The resulting mixture was then cooled to a temperature of less than 19°C at a tip speed of 600rpm to obtain a dry cathode composite DCC- II.

[0111] The dry cathode composition DCC-II was then calendared to obtain a cathode film- II. The cathode film- II was then laminated upon a carbon pre-coated aluminium current collector to obtain Cathode-II.

[0112] Similarly, a comparative cathode-IIa was prepared using 2.5% by weight of the binder composite BC-2 [2.5% of BC-2 comprising 0.5% by weight of PVDF- HFP (adhesive binder) 0.5 % of PTFE (fibrillating binder), and 1.5 % of Ketjen black and KS6L (primary carbon and secondary carbon), with respect to the total weight of the electrode], in the similar process conditions as mentioned above.

[0113] For the purpose of comparison, an electrode composition was tried to be prepared comprising less than 2% by weight of binders (adhesive and fibrillating binder). However, such an electrode composition could not form a film after calendaring and laminating due to the brittle nature. Therefore, the binder content in the electrode composition was desired to be in a range of 2 to 3%.EXAMPLE 3Characterization of the electrode compositionField emission Scanning electron microscopy (SEM):

[0114] The surface morphology of Cathode-IIa is depicted in Figure 3; and surface morphology of Cathode-I and Cathode-II are depicted in Figure 4 (i) (A-B) and Figure 4 (ii) (A-B) using FESEM analysis.

[0115] From Figure 3, it was observed that the Cathode-IIa exhibited non-uniform conductive carbon coating with agglomeration. Further, voids were also observed confirming non-uniform packing of particles. Furthermore, there was no compactness in the structure formed. This non-compact and non-uniform coating of particles along with carbon agglomeration in Cathode-IIa was understood to be leading to detrimental effects in its conductivity and thereby its electrochemical performance. Hence, it was found that when a binder composite comprising more than 55% by weight of carbon (primary and / or secondary carbon) would result in the total carbon content (primary carbon, secondary carbon, first conductive carbon and second conductive carbon) of the electrode (cathode) to be more than 2% with respect to the total weight of the cathode. Such high carbon content resulted in agglomeration while subjected to electrochemical cycling at higher c-rates.

[0116] Additionally, Figure 4 (i)(A), low magnification (zoomed out) image showed that, there were voids in-between cathode active material particles as well as the presence of thick fibrils. It also showed that there were no conducting carbons around cathode active materials. Hence, in the cathode-I, the cathode active material particles were not packed tightly together, which led to increased electrode resistance. Also, the presence of thick fibrils indicated high degree of agglomeration of the cathode active material particles, which led to reduced electrode performance and stability. Further, the absence of carbon particles around cathode active materials suggested that the binder content employed was not sufficient or effective enough to hold the cathode active material particles together.

[0117] In Figure 4 (i)(B), low magnification (zoomed out) image, it was observed that the Cathode-II had many thin fibrils attached to conducting carbons that were spread near and around cathode active material. Therefore, the conducting carbons (first and second) and thin fibrils present and distributed around the cathode activematerial particles in the Cathode-II. This indicated the lowering of electric resistance of the electrode, resulting in efficient charge transfer and energy storage. Also, the presence of conducting carbons and thin fibrils enable the electrode to operate at high c-rates, as it facilitated faster charge transfer and ion diffusion.

[0118] Figure 4 (ii)(A) high magnification image of Cathode-I showed that, cathode-I exhibited non-uniform conductive carbon coating. Further, voids were also observed and there was no compactness in the structure formed confirming non-uniform coating. Therefore, it was understood that when the electrode composition was prepared by direct addition of binder and carbons (primary and secondary), voids were observed.

[0119] Furthermore, Figure 4 (ii)(B) high magnification image of Cathode-II depicted that many thin conducting carbons decorated PTFE fibrils were attached to cathode active material particles. This suggested that the conducting carbons (first and second) and PTFE binder have been effectively blended throughout the electrode composition, and also the conducting carbon decoration on the PTFE fibrils which enhanced the electrical conductivity of the electrode, resulting in efficient charge transfer and energy storage. Further, the presence of these fibrils helped to reduce particle agglomeration, allowing for more uniform dispersion of cathode active material particles in the electrode, and facilitate faster charge transfer and ion diffusion. Hence, the problem of developing an internal resistance when higher c-rates were employed, got mitigated.

[0120] In conclusion, it was understood from the FESEM analysis that when a binder composite comprising more than 55% by weight of carbon (primary carbon or combination of primary carbon and secondary carbon) was employed, it resulted in the agglomeration and non-uniform distribution of the components in the corresponding electrode. This agglomeration and voids would lead to development of internal resistance during electrochemical cycling.

[0121] Therefore, employing disclosed weight ranges of the adhesive and fibrillating binders along with primary carbon in the form of the disclosed binder composite in an electrode composition resulted in better compactness and uniform distribution of carbon across the bulk of the electrode composition. Meanwhile, thedirect employment of adhesive and fibrillating binders along with primary carbon into the electrode (without using in the form of binder composite) can lead to agglomeration, poor fibrillation and voids in the electrode composition bulk.EXAMPLE 4Preparation of an electrochemical cell comprising the cathode

[0122] The electrochemical cell setup was obtained by sequentially assembling the cathode prepared by the process as explained in Example 2, and an anode with an electrolyte in between the cathode and the anode.

[0123] An electrochemical cell, specifically a battery, was prepared. The battery included a Cathode-II as explained in Example 2, a graphite anode disposed to face the cathode, and an electrolyte (LiPFe dispersed in a solvent mixture of ethylene carbonate (EC), vinylene carbonate (VC) and dimethyl carbonate (DMC)) placed between cathode and anode. The electrochemical cell obtained from the process explained above was analyzed for its electrochemical performance, C-rate performance, and charge-discharge capacity.

[0124] For the purpose of electrochemical analysis of the Cathode-I and Cathode- Ila explained in Example 2, a half-cell was prepared using each cathode with Li metal as anode.(b) Electrochemical analysis of the electrodes

[0125] The cathodes I and II prepared by the process as explained in Example 2, were subjected to electrochemical analysis in the form of a half-cell as explained above. The electrochemical analysis results of the cathodes I and II are provided in Table 2 and Figure 5. The initial coulombic efficiency (ICE) was analyzed for the half-cell by subjecting to sequential charging-discharging steps. The chargedischarge cycles of the nominal capacity measurements were carried out at a rate of 0.5C charge / 1C discharge.Table 2

[0126] The results showed that the cells comprising the Cathode-II prepared by the process (b) as disclosed in Example 2, exhibited improved Initial Coulombic Efficiency (ICE) and discharge capacity. The ICE of the cell prepared using the cathode-II was found to be 92.96% because of proper electronic networking and enhanced particle connectivity as found in the SEM results. This indicated that the binder composite reduced the internal resistance which improved the ICE values. Further, it was concluded that the binder composite also facilitated the formation of a stable, electronically conductive and homogenously distributed electrode structure.Similarly, half-cells prepared using Cathode-II using electrolyte were subjected to electrochemical analysis. It was observed that all of them maintained a discharge capacity of 214.41 and ICE value of 92.96% (Figure 6).State of health:

[0127] The capacity retention of the cathodes was also analyzed up to 50 cycles at 1C, and the cycle stability exhibited by the cathodes are given in Figures 7 (i) and (ii). The state of health (SoH) was calculated using the formula: SoH = (maximum available capacity of the current cycle / maximum available capacity of the initial cycle) x 100.

[0128] Figure 7(i) depicts that the Cathode-II of the Example 2 exhibited capacity retention of approximately 98.5% in 50 cycles, which was better when compared to Cathode-I.

[0129] Figure 7(ii) depicts that the Cathode-II exhibited capacity retention approximately in a range of 96 to 99% in 50 cycles at different temperatures of 25°C and 45°C.

[0130] Hence, it was inferred that the Cathode-II prepared by employing BC-1, showed better capacity retention at ambient and higher temperatures.Rate performance:

[0131] The rate performance of the cathodes prepared by the process as explained in Example 2 was analyzed by measuring the discharge capacity at different c-rates (Figure 8). Table 3 below provides the discharge capacity at different c-rates.Table 3

[0132] From Table 3 and Figure 8, it was observed that, the Cathode-II exhibited improved the discharge capacity of 91.53 at higher c-rates, and cycle stability when compared to the Cathode-I.Resistance:

[0133] The resistance of the electrodes was measured, and the values obtained are provided in Table 4. From Table 4, it was observed that the Cathode-II exhibited low resistance values in a range of 0 to 0.3 □, when compared to the Cathode-I which exhibited a resistance of 3.33 □.Table 4ADVANTAGES OF THE PRESENT DISCLOSURE:

[0134] The present disclosure provides a binder composite used in the preparation of battery electrodes such as anodes and cathodes. The electrode comprising binder composite of the present disclosure incurs less cost, consumes less energy and are economically viable. The present disclosure provides a process of preparing electrode which involves stepwise sequential mixing of binder along with conducting carbons to reduce the possibility of the carbon agglomeration into the slurry which will confer the homogeneous electrical conductivity in the electrodes throughout its length, and also helps in generating highly electrically conducting channels in electrodes which helps in conduction. The present disclosure further involves utilization of optimal weight ratio of conductive carbons in binder composite for obtaining desired peel strength. Further, the surface area of conducting carbons also improved the electronic conductivity and reduced internal resistance. The electrode prepared by utilizing the binder composite of the present disclosure therefore exhibits improved electrochemical efficiency. The binder composite of the present disclosure is suitable for preparing an anode as well as a cathode. Further, the electrochemical cells prepared using the electrodes comprising the binder composite of the present disclosure exhibits lesser resistance.

Claims

I / We Claim:

1. A binder composite, comprising: a. 10 to 55% by weight of a primary carbon; b. 22 to 45% by weight of an adhesive binder; and c. 22 to 45% by weight of a fibrillating binder, wherein the primary carbon has a surface area in a range of 1000 to 2000 m2 / g; and wherein the adhesive binder and the fibrillating binder are in a weight ratio range of 3:7 to 5:5.

2. The binder composite as claimed in claim 1, wherein weight of the primary carbon and combined weight of the adhesive binder and the fibrillating binder are in a ratio range of 10:90 to 55:45.

3. The binder composite as claimed in claim 1, wherein the primary carbon is selected from non-structured carbon black, high surface area carbon nanofiber, single walled carbon nanotube, or combinations thereof.

4. The binder composite as claimed in claim 1, wherein the fibrillating binder is selected from polytetrafluoroethylene (PTFE), fluoroethylene vinyl ether (FEVE), or combinations thereof; and the adhesive binder is selected from polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride, polyvinylidene fluoride-co- hexafluoropropylene (PVDF-HFP), modified polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), high molecular weight polyethylene (HMWPE) or combinations thereof.

5. The binder composite as claimed in claim 1, wherein the binder composite comprises 1 to 10% by weight of a secondary carbon having a surface area in a range of 10 to 80 m2 / g; and the secondary carbon is selected from synthetic graphite, structured carbon black, low surface area carbon nanofiber, low surface area carbon nano tubes, graphene or combinations thereof.

6. The binder composite as claimed in claim 1, wherein the binder composite exhibits a resistance in a range of 0.1 to 0.7 Q cm; a peelstrength in a range of 4 to 6 N / 25 mm; and a tensile strength in a range of 7 to 30 MPa.

7. A process of preparation of the binder composite as claimed in claim 1, the process comprising: mixing the adhesive binder, the fibrillating binder, the primary carbon and optionally a secondary carbon to obtain the binder composite.

8. The process as claimed in claim 7, wherein mixing is carried out at a temperature in a range of 10 to 20°C, and at a tip speed in a range of 15 to 21 m / s.

9. The process as claimed in claim 7, wherein the adhesive binder has a particle size in a range of 5 to 10 micrometer; and the fibrillating binder has a particle size in a range of 350 to 550 micrometer.

10. An electrode composition comprising: a. 95.5 to 97% by weight of an active material; b. 1 to 1.5% by weight of at least two conductive carbons; and c. 1 to 3% by weight of the binder composite as claimed in claim 1, wherein the at least two conductive carbons comprise a first conductive carbon, and a second conductive carbon in a weight ratio range of 1:0.1 to 2:0.5.

11. The electrode composition as claimed in claim 10, wherein the active material is selected from lithium nickel manganese cobalt oxide, nickel cobalt aluminium oxide, lithium iron phosphate, lithium iron manganese phosphate, or combinations thereof; the first conductive carbon is selected from non-structured carbon black, carbon nanofiber, carbon nanotube, or combinations thereof; and the second conductive carbon is selected from synthetic graphite, graphene, structured carbon black, graphitic carbon or combinations thereof.

12. The electrode composition as claimed in claim 10, wherein the first conductive carbon has a surface area in a range of 500 to 2000 m2 / g; and the second conductive carbon has a surface area in a range of 10 to 100 m2 / g.

13. The electrode composition as claimed in claim 10, wherein the electrode composition exhibits an initial coulombic efficiency (ICE) in a range of 90 to 95% and a state of health of 96 to 99%.

14. The electrode composition as claimed in claim 10, wherein the electrode composition exhibits a peel strength in a range of 1.5 to 6 N / 25mm; and a resistance in a range of 0.1 to 0.5 Q.

15. A process for preparing the electrode composition as claimed in claim 10, the process comprising: a. blending the active material with the primary carbon, the secondary carbon and the binder composite as claimed in claim 1 to obtain a first mixture; and b. high shear mixing the first mixture followed by cooling to obtain the electrode composition.

16. The process as claimed in claim 15, wherein blending is carried out at a tip speed in a range of 15 to 21 m / s, for a period in a range of 20 to 40 mins, and at a temperature in a range of 10 to 25 °C.

17. The process as claimed in claim 15, wherein high shear mixing is carried out at a speed in a range of 25 to 36 m / s at a temperature in a range of 60 to 80 °C; and cooling is carried out by mixing at a speed in a range of 5 to 10 m / s, until reaching a temperature in a range of 0 to 19°C.

18. The process as claimed in claim 15, wherein the electrode composition has a particle size in a range of 8 to 12 micrometer.

19. An electrochemical cell comprising: a. an anode; b. a cathode comprising the electrode composition as claimed in claim 10, coated on a current collector; and c. an electrolyte.

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