Lithium-ion battery capable of fast charging

Abstract

Disclosed is an integrated electrode separator comprising an electrode and a composite in-situ separator CIS and where the separator comprises a) a binder resin, b) inorganic particles P1, and c) second inorganic particles P2, the integrated electrode separator having an open porous structure and the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron. Also provided is a method of making the integrated electrode separator and the application of the integrated electrode separator in a battery or electrochemical cell.

Description

Lithium-ion-Battery Capable of Fast Charging

[0001] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This application was made with United States government support under DE-EE0009106 awarded by Department of Energy. The United States government has certain rights in the invention.

[0003] FIELD OF THE INVENTION

[0004] This invention relates to an integrated electronic separator ("IES") comprising a composite in-situ separator (CIS), its fabrication and its use in lithium-ion batteries as replacement for the free-standing separator.

[0005] BACKGROUND OF THE INVENTION:

[0006] Fast Charging (FC) of High-Energy density Li-ion Battery (HE-LIB) (High- Energy density meaning having greater than 1 mAh / cm2, preferably greater than 2 mAh / cm2) is key to adopting Electric Vehicles (EV) at the large scale. Moreover, there is a tradeoff between HE-LIB longevity and the charging rate (C-rate), i.e. the battery longevity is severely compromised when it is charged repeatedly at a high C- rates (above 3C). For example, increasing the charge rate of Li-ion cells from normal charging rate of C / 3 to C / 5 (charge in 3 -5 hrs respectively) to over 1-2C (charge in 60-30 min) is highly desirable, but those cells are pushed to their endurance limits.

[0007] Users of EVs typically charge their vehicle overnight. In these situations, it is acceptable for the users to charge their EVs for several hours (normal C-rate). But at times, such as when traveling, users prefer to fast charge their EVs in less than 30 min. However, the battery's charging capacity generally diminishes after many cycles of such fast charging.

[0008] Many research projects have been studied ways to facilitate fast charging. The previous solutions were mainly focused on improving Li-ion mass transport in electrodes and electrolytes, by changing the thickness and / or porosity of electrodes, or by using different additives and electrolyte, or by surface treatment of active materials to promote charge transfer kinetics. Such solutions had met limited success. Therefore, there is an urgent need to develop a HE-LIB that can undergo fast charging while maintaining its longevity. Longevity loss is measured by the lossof capacity retention over the number of cycles e.g., loss of 20% capacity over 200 cycles of change / discharge, thus; longevity loss is 20 / 200 per given cycles.

[0009] http : / / dx. doi.org / 10.1016 / j.jpowsour.2015.11.067 disclosed casting of aqueous separator slurry (comprising of micron-sized aluminum oxide and PVA) onto Li4Ti5O12(LTO) cathode. The produced separator coating on top of the electrode was limited in its flexibility and was 50 μm thick, thicker than commercially available PE / PP separators. The battery exhibits limited performance at elevated discharge conditions (2 C).

[0010] http: / / dx.doi.org / 10.1016 / j.memsci.2016.02.047 disclosed fabrication of a freestanding aluminum oxide separator using micron-sized aluminum oxide and pore-forming agent PEG, visible by SEM. The produced separator was 37 μm thick, thicker than commercially available PE / PP separators.

[0011] US20160164060 discloses an aqueous process for coating separators. The process comprises the steps of: (a) providing a porous substrate, (b) applying a coating slurry on at least one surface of the porous substrate, wherein the coating slurry comprises ceramic particles and polymeric binders in water or an aqueous solution or suspension, and (c) drying the coating slurry to form a coating layer on the porous substrate.

[0012] US9954211 discloses a separator including a porous organic-inorganic coating layer composed of a mixture of inorganic particles and a binder polymer on a porous substrate, and an electrochemical device including the separator.

[0013] US7662517 discloses an organic / inorganic composite porous separator where the composite separator was made by coating a polyolefin based separator.

[0014] US20100330268 discloses a battery separator that is formed directly on one of the electrodes. This porous separator layer is comprised of silica particles dispersed in a polymeric matrix. The method of forming a battery separator directly onto an electrode comprising spraying a solution or dispersion comprising silica particles and a polymer onto the electrode. Prior to spraying the separator, the electrode is heated to 130 - 140C, suggesting on the electrode is already dried prior to applying the separator slurry.

[0015] US20210135237 discloses an electrochemical cell with integrated ceramic separator. This patent provides examples of different methods to produce the IES,including slot die, blade coating, spray-based coating, electrostatic jet coating. Also described is an interlocking region between the separator layer and the electrode layer.

[0016] US11133562 relates to integrated electrode separators (IES), and their use in lithium ion batteries as replacements for free standing separators.

[0017] https: / / doi.org / 10.1016 / j.jpowsour.2020.228475 discloses fast charging LIB capability enabled by laser-patterned three-dimensional graphite anode architecture. Our invention can achieve fast charging capability through the IES with no need for modification of the anode.

[0018] There remains a need to increase the life (longevity) of a HE-LIB that undergoes fast charging.

[0019] Applicants have found that a battery which comprises an IES in the which interfaces between electrode and separator is diffused (eliminating the abrupt interface generally found between electrode and separator) and having ceramic particles of two different sizes in the separator portion of the IES, can withstand the negative effects of fast charging (decreased longevity) resulting in longer life. Without being bound by theory it is believed that the novel IES provides for enhanced ionic mobility within the separator

[0020] One way to produce the diffused interfaces is by coating a separator slurry having inorganic particles, such as alumina, and binder directly onto the wet electrode, followed by drying of the combined wet separator and electrode coatings to produce an IES where the CIS has porosity and adheres well to the electrode and exhibits a diffused interface between the electrode and separator. By coating wet separator slurry on wet electrode slurry, the interface between the two wet slurries intermix at the boundary producing a diffused interface.

[0021] The IES may provide one or more advantages, including (1) reducing the cost associated with the separator component by 60-65 % or more by using the composite In-situ separator described in the invention (CIS) as a replacement for a free-standing polymeric separator, (2) simplifying the manufacturing process of the battery by utilizing integrated electrode separator (IES), (3) improving the performance and safety of the batteries compared to those manufactured usingexisting technology, and (4) more surprisingly and unexpectedly, allowing fast charging without compromising the longevity of HE-LIBs.

[0022] One challenge associated with fast charging is the anode exhibits an increase in volume due to migration of lithium-ions to the anode during charging. The rapid increase in volume of the anode causes strain inside the cell. Surprisingly, it has now been found that internal space may be created within the battery for internal expansion, by using the IES which contains at least two different size inorganic particles in the composite in-situ separator to create an irregular surface morphology. The irregular surface provides internal space for rapid internal expansion of anode with minimum stain on separator or electrodes within the cell, thus facilitating a better battery performance at fast charging. In the battery the internal space between the IES and adjoining electrode that makes the cell, allows less hindered ionic mobility and unobstructed ion transport and also allows expansion of the battery components during the charging and discharging cycle, with little or no increase in the size of the battery itself. For example, if the IES is an anode then there will be voids between the IES and the cathode.

[0023] SUMMARY OF THE INVENTION

[0024] Disclosed is an integrated electrode separator ("IES") which compromises a composite in situ separator ("CIS") and an electrode. The CIS of the IES is comprised of binder resin and inorganic particles, P1 and P2, where P1 and P2 have different particle sizes, P1 has a volume average secondary particle size of less than 500 nm, and P2 has a volume average particle size of greater than 1.0 micron The P1 particle may fill in between the P2, reducing the pore size of the CIS.

[0025] There is no distinct interface between the CIS and the electrode. The interface is diffuse as a result of the way the IES is fabricated. The diffuse interface interlocks the separator to the electrode. The IES provides can have one of more of the following advantages, including: forming a thinner and more uniform separator layer which improves cell performance; eliminating the need for a free-standing separator which reduces the cell cost; simplifying the battery manufacturing process which reduces off-spec products; surprisingly and unexpectedly enables enhanced battery longevity and better performance (as measured by capacity retention aftercycle time) at fast charging compared to conventional batteries made with a freestanding separator.

[0026] A battery for EV is considered to have reached its end of life once its capacity has faded more than 80% according to "United States Advanced Battery Consortium ("USABC") Electric Vehicle Battery Test Procedure Manual" Revision 3 June 2015.

[0027] The IES component (also referred herein to as IES) can be fabricated by different methods so long as the interface created is diffuse. An electrochemical cell or battery according to the present invention will include one or more electrodes having a composite in-situ separator (the IES) but will not contain a free standing separator. The IES includes a current collector and an active material layer on the current collector, and an integrated separator layer, and most preferably with an interlocking region, also referred to as a diffuse region or diffuse interface, interlocking / connecting directly the active material layer and integrated separator layer. The interlocking region or diffuse interface is non-planar and interlocks the active material layer and integrated separator layer.

[0028] The IES can be fabricated by casting of the electrode slurry containing the active material onto a current collector and then casting the slurry used to form the CIS directly onto the casted electrode slurry and then followed by drying for the IES. The casting process could be either a solvent cast or waterborne cast process. There is no distinct boundary between the CIS and the casted electrode slurry forming the electrode layer having the active material.

[0029] The IES component can also be fabricated via a dry process by using powder coating technology. A powdery electrode mixture containing the active material and binder Resin A is electro-sprayed onto a current collector, followed by electrospraying of a powdery mixture comprising P1, P2 and binder resin B, ("the powdery composite in-situ separator mixture ") onto the electrode. The IES can then be heated and / or densified. Optionally the electrode layer or the electrode plus CIS layers are heated and / or densified to form the IES.

[0030] The invention relates to an integrated electrode separator comprising at least one electrode having directly adhered to it a porous composite separator layer comprising interconnected particles in the form of a CIS. The CIS comprises non-conductive inorganic particles P1 and P2 wherein the volume average secondary particle size of P1 are less than 500 nm and the volume average particle size Particle P2 is greater than 1 micron.

[0031] The CIS may optionally contain inorganic particles and other additives that can improve cell performance such as higher ionic mobility and / or higher use temperature.

[0032] Optionally the CIS can be on both electrodes (anode and cathode) in an electrochemical cell or battery. Each electrode can independently be waterborne cast or solvent cast from corresponding respective slurries.

[0033] Moreover, this invention relates to composite in-situ separators and their use in lithium-ion batteries as replacements for free standing separators. The composite in-situ separator may optionally contain inorganic particles and other additives to improve electrode performance such as high ionic conduction or higher temperature usage.

[0034] The invention also relates to integrated electrode separator as part of a battery, capacitor, electric double layer capacitor, membrane electrode assembly or fuel cell.

[0035] Some Embodiments of the Invention

[0036] Embodiment 1 is an integrated electrode separator comprising an electrode and a composite in-situ separator CIS and where the separator comprises a) a binder resin, b) inorganic particles P1, and c) second inorganic particles P2, said integrated electrode separator having an open porous structure, wherein the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron.

[0037] The integrated electrode separator of Embodiment 1, wherein the inorganic particles P1 are anionic and have a specific surface area of between 50 m2 / g and 1000 m2 / g.

[0038] The integrated electrode separator of Embodiment 1, wherein the inorganic particles P1 are anionic and have a specific surface area of between 50 m2 / g and 700 m2 / g.

[0039] The integrated electrode separator of any one or more of the previous embodiments, wherein the second inorganic particles P2 are electronically nonconductive and have a specific surface area of between 0.1 m2 / g and 20 m2 / g.

[0040] The integrated electrode separator of any one or more of the previous embodiments, wherein the binder resin has a solution viscosity of between 100 cp and5,000 cp at 5 wt % in NMP, at 25°C and 10 sec-1.

[0041] The integrated electrode separator of any one or more of the previous embodiments, wherein the binder resin has a solution viscosity of between 100 cp and 3,000 cp at 5 wt % in NMP, at 25°C and 10 sec-1.

[0042] The integrated electrode separator of any one or more of the previous embodiments, wherein the binder resin has a solution viscosity of between 100 cp and 5000 cp at 2 % in water, at 25°C and 10 sec-1.

[0043] The integrated electrode separator of any one or more of the previous embodiments, wherein the binder resin has a solution viscosity of between 100 cp and 3000 cp at 2 % in water at 25°C and 10sec-1.

[0044] The integrated electrode separator of any one or more of the previous embodiments, wherein the binder resin is selected from the group consisting of carboxymethyl cellulose CMC, poly vinyl alcohol (PVOH), polyacrylic acids (PAA), polyvinyl pyrrolidone (PVP), polyvinylidene fluoride (PVDF), PVDF-copolymers, poly ethylene-tetrafluoride ethylene PETFE, Polyvinyl fluoride (PVF), poly acrylates, poly methacrylates, poly styrene, polyesters, polyamides, poly acrylonitrile, poly acrylamide, and their copolymers and combinations thereof.

[0045] The integrated electrode separator of any one or more of the previous embodiments, wherein ratio of binder resin to total inorganic particles (P1 and P2) in the CIS is from 1 part binder resin: 99 parts inorganic particles to 40 parts binder resin: 60 parts inorganic particles based on weight percent.

[0046] The integrated electrode separator of any one or more of the previous embodiments, wherein the ratio of binder resin to total inorganic particles (P1 and P2) in the CIS is from 2 parts binder resin: 98 parts inorganic particles to 30 parts binder resin: 70 parts inorganic particles based one weight.

[0047] The integrated electrode separator of any one or more of the previous embodiments, wherein the ratio of binder resin to total inorganic particles (P1 andP2) in the CIS is from 2 parts binder resin : 98 parts inorganic particles to 10 parts binder resin: 90 parts inorganic particles based on weight.

[0048] The integrated electrode separator of any one or more of the previous embodiments, wherein the amount of P1 is at least 5wt% based on the total wt of P1 plus P2 and up to 50wt% based on total wt of P1 and P2.

[0049] The integrated electrode separator of any one or more of the previous embodiments, wherein the interface between the separator and electrode is diffused.

[0050] The integrated electrode separator of any one or more of the previous embodiments, wherein the CIS has from 20 % to 80 % open pores, preferably 20 to 60% open pores.

[0051] The integrated electrode separator of any one or more of the previous embodiments, wherein average thickness of the CIS is greater than 5 microns and less than 40 microns as measured by SEM-EDX (Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) analysis). The inorganic particles (P1 and P2) of the CIS can be differentiated from the active materials of the electrode under SEM- EDX. The thickness of the CIS is determined based on where the materials of the CIS are no longer detected by SEM-EDX in the IES. If particles of the CIS and the active materials of the electrode are intermixed in a region of the interface such that both are detected in that region then that is considered part of thickness of the CIS.

[0052] The invention provides embodiments for a method of making an integrated electrode separator (IES) comprising providing an electrode slurry, providing a composite in-situ separator slurry, casting the electrode slurry onto a current collector, casting the separator slurry on to the wet electrode thereby forming an assembly, drying the assembly to form the integrated electrode separator. This method can be used to make any of the previous embodiment of the integrated electrode separator.

[0053] The invention provides embodiments for a method for forming an integrated electrode separator assembly comprising the steps of: a. forming an electrode pre-mix slurry, wherein the electrode pre-mix slurry comprises active material and at least one binder resin A, said electrode pre-mix slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C;b. forming a composite in-situ separator slurry comprising P1 and P2 and at least one binder resin B, said composite in-situ separator slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C; c. casting the electrode pre-mix slurry onto a current collector to form a wet electrode; d. forming a composite in-situ separator (CIS) by casting the composite in-situ separator slurry onto the at least one wet electrode formed in step c to form an assembly; and e. drying said assembly, to form an integrated electrode separator, wherein the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron.The binder resin A can be the same or different from the binder resin B. This method can be used to make any of the previous embodiments of the integrated electrode separator.

[0054] In some method embodiments the electrode pre-mix slurry and composite in-situ separator slurry may both be water born slurries.

[0055] In some method embodiments the electrode pre-mix slurry and composite in-situ separator slurry can both be solvent born slurries.

[0056] In any one or more of the method embodiments the electrode pre-mix slurry and composite in-situ separator slurry can be cast concurrently onto a current collector and then dried to form an integrated electrode separator.

[0057] In any one or more of the method embodiments the binder resin of the electrode pre-mix slurry and the binder resin of the composite in-situ separator slurry can be the same binder resin or can be miscible binder resins.

[0058] In any one or more of the method embodiments the interface between the electrode and separator can be diffuse.

[0059] One embodiment provides for a method of making an integrated electrode separator (IES) component comprising electro-spraying an electrode mixture in powder form ("powdery electrode mixture") onto a current collector to create an electrode powder coating on the current collector, followed by electro-spraying a composite in-situ separator mixture in powder form ("powdery composite in-situseparator mixture") onto the electrode powder coating. Solvent is not used in this method.

[0060] One embodiment of the invention provides for a method of forming an integrated electrode separator comprising the steps of: a. forming a powdery electrode mixture comprising a powdery cathode mixture or a powdery anode mixture, said powdery electrode mixture comprises at least one binder resin A and active material; b. forming a powdery composite in-situ separator mixture comprising P1, P2, and at least one binder resin B; c. coating the powdery electrode mixture onto a current collector to form an electrode; d. forming composite in-situ separator (CIS) by coating powdery composite in-situ separator mixture directly onto the electrode of step c to form an assembly; and e. heating and / or compressing the assembly, to form an integrated electrode separator,The binder resin of A can be the same or different from the binder resin B. Solvent is not used in this method. This is considered a dry method.

[0061] In some of the method embodiments utilizing powdery materials in powder form ("powdery materials") the powdery electrode mixture plus powdery composite in-situ separator mixture can be heated and compressed after electrospraying the powdery composite in-situ separator mixture onto the electrosprayed powdery electrode mixture as a finished product to form the IES component, wherein the electrode mixture is not heated or compressed prior to the electrospraying of the composite in-situ separator powder mixture.

[0062] In the method embodiments utilizing powdery material, the electrode can be heated and compressed, before the powdery composite in-situ separator mixture is applied to the electrode followed by the electrode with the powdery composite in-situ separator mixture being heated and compressed.

[0063] In the method embodiments utilizing powdery material, the binder resin of the powdery electrode mixture and the binder resin of the powdery composite in-situ separator mixture can be the same binder resin or can be miscible binder resins.

[0064] In the method embodiments utilizing powdery material the interface between the electrode and separator can be diffuse.

[0065] One embodiment the invention provides for a battery comprising the IES of any of the integrated electrode separator embodiments.

[0066] One embodiment the invention provides for an electrochemical cell comprising the IES of any of the integrated electrode separator embodiments.

[0067] One embodiment the invention provides for a battery comprising the IES of any of the integrated electrode separator embodiments, wherein the state of health of the battery is greater than 80% when repeatedly charged at 4C for 500 cycles, preferable greater than 80% when repeatedly charged at 4C for 700 cycles, more preferably greater than 80% when repeatedly charged at 4C for 1000 cycles.

[0068] In one embodiment the invention provides for a battery comprising the IES of any of the integrated electrode separator embodiments, and wherein the state of health of the battery is greater than 80% when it is repeatedly charged at C / 2 for 500 cycles, preferable greater than 80% when repeatedly charged at C / 2 for 700 cycles, more preferably greater than 80% when repeatedly charged at C / 2 for 1000 cycles.

[0069] The thickness of the composite in-situ separator in the battery may be less than 40 microns.

[0070] In any of the battery embodiments wherein the only separator present can be the composite in-situ separator. Some embodiments there is no polyolefin separator.

[0071] In any of the battery embodiments the porosity of the IES component may be greater than 20%, preferably greater than 30%.

[0072] Some embodiments provide a battery comprising the IES of any one of the above embodiments, wherein the state of health of the battery is greater than 90% when repeatedly charged at 15C for 5 cycles, preferable greater than 80% when repeatedly charged at 15C for 100 cycles. Preferably, the thickness of the composite in situ separator is less than 40 microns.

[0073] The battery of any one of the above embodiments, wherein the battery comprises one IES comprising an anode and wherein the cathode is not part of an IES.

[0074] A battery comprising integrated electrode separator comprising an electrode and a composite in-situ separator and where the composite in-situ separator comprises a) a binder resin, b) inorganic particles P1, and c) second inorganic particles P2, said integrated electrode separator having an open porous structure, wherein the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron, wherein the battery comprises one IES comprising an anode and wherein the cathode is not part of an IES, wherein the state of health of the battery is greater than 90% when repeatedly charged at 15C for 5 cycles, preferable greater than 80% when repeatedly charged at 15C for 100 cycles.

[0075] DETAILED DESCRIPTION OF THE INVENTION

[0076] "Copolymer" is used to mean a polymer having two or more different monomer units. "Polymer" is used to include homopolymer and copolymers. Resin and polymer are used interchangeably. The polymers may be homogeneous, heterogeneous, and may have a gradient distribution of co-monomer units. As used herein, unless otherwise described, percent shall mean weight percent. Unless otherwise stated, molecular weight is a weight average molecular weight as measured by GPC, using a polymethyl methacrylate standard. Melting temperatures are measure by DSC as described in ASTM D3418 at heating rate of 10 C / min. Melt viscosity is measured in accordance with ASTM D3835 at 230°C expressed in kPoise @100 Sec-1. Solution viscosity of polymers (at 5 wt.% solution) is measured as described in ASTM D2857 at 25C.

[0077] All references cited are incorporated herein by reference.

[0078] Nano sized for filler or nano size particles means that the filler or particles have a particle size of less than 500 nm preferably less than 200 nanometers. The nano size particles can be less than 100 nm. Particle size is volume average secondary particle size as measured by light scattering (such as by a Nicom, or Microtech instrument).

[0079] By high energy meaning having greater than 1 mAh / cm2, preferably greater than 2 mAh / cm2.

[0080] By high specific surface area particles means that the surface area of the particles is greater than 50 m2 / g. Preferably Inorganic particles P1 have a surface area greater than 50 m2 / g, more preferably greater than 60 m2 / g. Preferably P1 has a surface area of between 50 m2 / g and 1000 m2 / g, more preferably between 50 m2 / g and 700 m2 / g, and even more preferably between 50 m2 / g and 500 m2 / g. The surface area of P1 can be between 50 and 700 m2 / g.

[0081] By high molecular weight we mean having solution viscosity of at least 100 cp at 5% in NMP at 25°C. Preferably the binder resin of the invention has a solution viscosity of between 100 cp and 5,000 cp, more preferably between 100cp and 3000cp.

[0082] By high-energy density lithium-ion-battery (HE-LIB) means electrodes contain at least 90wt % active materials in the electrode layer on the conductive substrate. The composition of the electrode layer in the HE-LIB preferably contains between 90 to 98wt% active materials, more preferably between 92 to 97wt% active materials based on weight of the electrode layer.

[0083] By charging cycle means charging at constant current followed by constant voltage (CC-CV method) where charging stops when current drops below 0.1C.

[0084] 1C means that the battery is charged, or discharged within one hour, 2C is 30 minutes, and so on 10C=6mins, 100C=36 seconds.

[0085] By discharging cycle means discharging at constant current methodology.

[0086] constant current-constant voltage (CC-CV method) method is a battery charging technique that uses a constant current to start, then switches to a constant voltage to finish.

[0087] By capacity check cycle means charging at constant current at 0.1C followed by constant voltage (CC-CV method), for example 4.2V is used for NMC622, where charging stops when current drops below 0.05C.

[0088] By fast charging cycle means charging at 4C constant current follow by constant voltage (CC-CV method) where charging stops when current drops below 0.1 C or when charge time exceeds 15 minutes.

[0089] By fast charging or fast charge means in accordance with the US Advanced Battery Consortium Goal for Fast-Charge of Advanced Batteries for EVs - CY 2023. To charge batteries to 80% of state of charge in 15 minutes (equals 4C). Themetric was taken from energy storage system performance targets for EVs "Battery Test Manual for electric vehicles USDOE 2015".

[0090] By higher temperature usage means operation of the battery above 25°C, preferably greater than 45°C, more preferable greater than 60°C.

[0091] An active material termed "active" because it exhibits electrochemical activity towards lithium. Active materials for battery electrodes are known in the art. Examples of active materials in the negative electrode include but are not limited to lithium metal, graphite, graphene, silicon / carbon composites, silicon, fluorographites of CFxtype where x is between 0 and 1 and titanates of LiTi5O12type. Examples of active materials in the positive electrode include but are not limited to the LiMO2type, the LiMPO4type, the Li2MPO3F type, where M is Co, Ni, Mn, Fe, the LiMn2O4type, the S8type or the lithium polysulfide type or NMC type active material or a combination of these.

[0092] An integrated electrode separator is a component comprising an electrode constituting a current collector and an active electrode layer there upon and a composite in-situ separator CIS integrally provided on and in direct contact with the active material layer.

[0093] By composite in-situ separator we mean a film or coating with a porous open matrix structure. "Open" means the pores are not enclosed. Fluids can move between and through pores. The porosity can be measured by density measurement. The density of the CIS can be measured by sequentially microtoming of the IES and then the porosity can be calculated from loss of mass and volume from microtomed IES. The change in thickness of the material can be measured by micropicometer. Pycnometer can be used to measure the solid density of the microtomed material. THE INVENTION

[0094] The invention provides an integrated electrode separator ("IES") component comprising an electrode and a composite in-situ separator CIS where the composite in situ separator comprises a) a binder resin, b) inorganic particles P1, and c) second inorganic particles P2 , said integrated electrode separator composite having an open porous structure, wherein the volume average secondary particle size of P1 is less than 0.5 micron, and the volume average particle size particle size of P2 is greater than 1.0 micron. (SEM-EDX).

[0095] The composite in-situ separator CIS used in this invention exhibits better wettability with electrolyte compared to the free-standing polyolefin-based separator. When specimens of CIS or free-standing polyolefin-based separators are exposed to electrolyte solvent, CIS exhibits faster wicking. Because there is better compatibility between the CIS and the ion transporting media or electrolyte, the ion movement between positive and negative electrodes will be faster as compared to using a freestanding polyolefin-based separator. Visually this can be observed when electrolyte is placed onto the separator or IES.

[0096] The CIS comprises a) a binder resin, b) inorganic particles P1 and c) inorganic particles P2. The CIS has an open porous structure. The binder resin has a solution viscosity of from about 100 cp to 5,000 cp, preferably from 100 cp to 3000 cp (at 5 wt% in NMP (N-Methylpyrrolidone) or at 2% water for water soluble binder resins at pH 7, at 25C and at 10 s-1).

[0097] The open pores are nano-sized.

[0098] Preferably the porosity of the CIS is from 20 % to 80 % open pores, preferably 20 to 60% open pores.

[0099] The weight percent of binder resin to total inorganic particles (P1 and P2) in the CIS of this invention is from 1 part binder resin:99 parts inorganic particles to 40 parts binder resin:60 parts inorganic particles, preferably from 2:98 to 30:70, more preferably from 2:98 to 10:90.CHARACTERISTICS OF THE COMPOSITE IN-SITU SEPARATOR

[0100] The CIS of this invention has the average pore size of less than 500 nm, preferably less than 100 nm, and more preferably less than 50 nm as measured by SEM-EDX. The average pore size in the CIS is preferably from 2 nm to 500 nm, more preferably from 2 to 100nm.

[0101] For this invention, the average thickness of the CIS is measured by measuring the average distance of the layer formed by the P1 and P2 particles by SEM-EDX. The average thickness of the CIS is greater than 5 microns and less than 40 microns as measured by SEM-EDX.

[0102] The preferred porosity of IES for fast charging is greater than 20%, preferably greater than 30%, % but less than 80%.BINDER RESINS

[0103] The binder resin for the CIS of this invention (Binder resin B), can be selected from the group consisting of carboxymethyl cellulose CMC, Polyacrylic acids (PAA), polyvinyl pyrrolidone (PVP), Poly vinyl alcohol (PVOH), Polyvinylidene (PVDF), polyethylene-tetrafluoride ethylene PETFE, Polyvinyl fluoride (PVF), poly acrylates, poly methacrylates, poly styrene, poly acrylonitrile, poly acrylamide, and their copolymers and combinations thereof.

[0104] Binder resin used for the electrode of the IES of this invention ("Binder Resin A") can be selected from any of the same binder resins as Binder resin B.

[0105] The binder resin has a solution viscosity of 100 cp or greater at 5% in NMP at 25°C. Preferably, the solution viscosity is between 100 and 5,000 cp, more preferably between 100 and 3000 cp measured at 5% solids in NMP at 25C, 10 s-1. Binders such as Poly vinyl alcohol (PVOH), Polyvinylidene (PVDF), polyethylene- tetrafluoride ethylene PETFE, Polyvinyl fluoride (PVF), poly acrylates, poly methacrylates, poly styrene, poly acrylonitrile, poly acrylamide, and their copolymers and combinations thereof are soluble in NMP at 5% and 25°C.

[0106] If the binder resin is not soluble in NMP but is a water soluble polymer such as polyacrylic acid, carboxyl methyl cellulose, polyvinyl pyrrolidone, the solution viscosity is from 100cp to 5000 cp, preferably between 100 cp and 3000 cp as measured in water at 2% solids and pH of 7 at 10 sec-1 at 25°C. If a binder resin is soluble in both NMP and water, then the NMP solution viscosity is used.

[0107] In some embodiments, the binder resin is a polyvinylidene fluoride homopolymer or copolymer. The term "vinylidene fluoride polymer" (PVDF) used herein includes both homopolymers and copolymers within its meaning.Copolymers of PVDF are particularly preferred, as they have a lower melting point and a reduced crystalline structure compared to the PVDF homopolymer. Such copolymers include vinylidene fluoride copolymerized with at least one comonomer. The vinylidene fluoride monomer may make up at least 75 mole percent of the monomer units in the polymer, and other ethylenically unsaturated monomer units make up the remaining percentage of monomer units. Most preferred PVDFcopolymers of the invention are those in which vinylidene fluoride units comprise at least 75 mole percent, preferably at least 80 mole %, and even more preferably at least 85 mole % of the total moles of all the monomer units in the polymer.

[0108] Copolymers of vinylidene fluoride may be made by reacting vinylidene fluoride with one or more monomers. The comonomer can be a fluorinated monomer Example fluorinated monomers include vinyl fluoride, trifluoroethene, tetrafluoroethene, one or more of partly or fully fluorinated alpha-olefins such as 3,3,3-trifluoro-1-propene, 1,2,3,3,3-pentafluoropropene, 3,3,3,4,4-pentafluoro-1- butene, and hexafluoropropene, the partly fluorinated olefin hexafluoroisobutylene, perfluorinated vinyl ethers, such as perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoro-n-propyl vinyl ether, and perfluoro-2-propoxypropyl vinyl ether, fluorinated dioxoles, such as perfluoro(1,3-dioxole) and perfluoro(2,2-dimethyl-1,3- dioxole), allylic, partly fluorinated allylic, or fluorinated allylic monomers, such as 2- hydroxyethyl allyl ether or 3-allyloxypropanediol. In some preferred embodiments the comonomer is selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinyl fluoride, pentafluoropropene, tetrafluoropropene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether. Preferred are copolymers comprised of vinylidene fluoride and hexafluoropropene polymerized monomer units. Copolymers of vinylidene fluoride comprising non-fluorinated monomer unit are also envisioned. Examples non-fluorinated monomer include ethane, propene, acrylic monomers methacrylic monomers and other monomers known in the art to copolymerize with vinylidene fluoride.

[0109] In some embodiments the binder resin can be a copolymer consisting of vinylidene fluoride and hexafluoropropene or is a homopolymer of vinylidene fluoride.

[0110] Particularly preferred for separator binder resins are copolymers composed of from at least about 75 and up to 98 mole percent vinylidene fluoride, and correspondingly from 2 to 25 mole percent hexafluoropropene. Copolymers of vinylidene fluoride, hexafluoropropene and tetrafluoroethylene aarree also representatives of the class of vinylidene fluoride copolymers, embodied herein. Inone embodiment the fluoromonomers consist of vinylidene fluoride and hexafluoropropene.

[0111] In one embodiment, up to 50%, preferably up to 20%, and more preferably up to 15%, by weight of hexafluoropropene (HFP) units and 50%, preferably 80%, and more preferably 85%, by weight or more of VDF units are present in the vinylidene fluoride polymer. It is desired that the HFP units be distributed as homogeneously as possible to provide PVDF-HFP copolymer with excellent dimensional stability in an end-use environment - such as in a battery.

[0112] Fluoropolymers such as polyvinylidene-based polymers are made by any process known in the art. Processes such as emulsion and suspension polymerization are preferred. Exemplary processes are described in US6187885, and EP0120524.Acrylic binder resin

[0113] Acrylic polymers can be used as binder resins. Acrylic polymers as used herein is meant to include homopolymers and copolymers formed from methacrylate and acrylate monomers, and mixtures thereof. The methacrylate monomers and acrylate monomers may make up from 51 to 100 percent of the monomer units in the polymer, and there may be 0 to 49 percent of other ethylenically unsaturated monomer units. Other ethylenically unsaturated monomers include but not limited to, styrene, alpha methyl styrene, and acrylonitrile. Suitable acrylate and methacrylate monomers and comonomers include, but are not limited to, methyl acrylate, ethyl acrylate and ethyl methacrylate, butyl acrylate and butyl methacrylate, iso-octyl methacrylate and acrylate, lauryl acrylate and lauryl methacrylate, stearyl acrylate and stearyl methacrylate, isobornyl acrylate and methacrylate, methoxy ethyl acrylate and methacrylate, 2-ethoxy ethyl acrylate and methacrylate, dimethylamino ethyl acrylate and methacrylate monomers. (Meth) acrylic acids such as methacrylic acid and acrylic acid can be comonomers. Acrylic polymers include multilayer acrylic polymers such as core-shell structures which can be made by emulsion polymerization.Styrene

[0114] Styrenic polymers can be used as binder resins. Styrenic polymers as used herein is meant to include homopolymers and copolymers formed from styrene and alpha methyl styrene monomers, and mixtures thereof. The styrene and alpha methyl styrene monomer unit may make up from 50 to 100 percent of the monomer units, and there may be 0 to 50 percent of other ethylenically unsaturated monomer units, including but not limited to acrylates, methacrylates, acrylonitrile. Styrene polymers include, but are not limited to, polystyrene, acrylonitrile-styrene-acrylate (ASA) copolymers, styrene acrylonitrile (SAN) copolymers, styrene-butadiene copolymers such as styrene butadiene rubber (SBR), methyl methacrylate-butadiene-styrene (MBS), and styrene-(meth)acrylate copolymers such as styrene-methyl methacrylate copolymers (S / MMA).PARTICLES P1 and P2.

[0115] The CIS comprises at least two different size inorganic particles, P1 and P2.

[0116] The separator slurry composition used to make the CIS contains inorganic particles P1 and P2 and resin binder.

[0117] The inorganic particles (P1 and P2) are electrochemically stable meaning they are not subjected to oxidation and / or reduction at the range of from 0.05 volts to 4.45 volts. The inorganic particles P1 and P2 may independently be selected from the group consisting of alumina, Al2O3, silica, SiO2, BaO, bohemite, SiC, boron silicate, nano-clays, or mixtures thereof.

[0118] P1 comprises anionic oxide nanoparticles. In some embodiments, P1 is a metal oxide, preferably a fumed metal oxide. Examples of fumed metals oxides include, but are not limited to, alumina, Al2O3, silica, SiO2, and combinations thereof. The metal oxides may be used in combination with each other. For example, fumed alumina may be used with fumed silica; fumed silica may be used with nanoclays. In one embodiment, the P1 is alumina or silica, most preferred is anionic fumed alumina, anionic fumed aluminum oxide and / or anionic fumed silica.

[0119] The anionic oxide nanoparticles at 5wt% solids in water at 25 °C have an anionic charge with a negative Zeta potential of less than -10 mv according to ASTM- D4187.

[0120] Inorganic particles P1 have a volume average secondary particle size of less than 0.5 micron, preferably less than 350 nm, preferably less than 300 nanometers. The P1 can be less than 200 nm. The particles may be fractal of a variety of shapes, such as, but not limited to, rectangular, spherical, fractal, elliptical, cylindrical, oval, dog-bone shaped, or amorphous. Particles size is volume average secondary particle size as measured by light scattering, Nicom, or Microtech instrument.

[0121] The P1 particles are anionic charged and have a surface area greater than 50 m2 / g of greater, more preferably 60 m2 / g or greater. Preferably P1 has a surface area of between 50 m2 / g and 1000 m2 / g, more preferably between 50 m2 / g and 700 m2 / g, and even more preferably between 50 m2 / g and 600 m2 / g. The surface area of P1 can be between 50 and 700 m2 / g.

[0122] Inorganic particles P2 have a volume average particle size of greater than 1 micron, preferably greater than 5 microns. The inorganic particles P2, may, independently of P1, be selected from the group consisting of alumina, Al2O3, silica, SiO2, BaO, bohemite, SiC, boron silicate, nano-clays, or mixtures thereof.

[0123] The P2 particles have a surface area less than 20 m2 / g or less. Preferably P2 has a specific surface area of 0.1 to 20 m2 / g.

[0124] As generally understood in the art, fumed metal oxides contain agglomerated or aggregated clusters of primary particles. The "primary particles" of fumed metal oxides are understood to be the smallest particles that are visible in high-resolution TEM images, which cannot be broken down any further. Primary particles may range in size from about 5 nm to about 100 nm. Several primary particles can congregate at their points of contact to form a secondary structure. As used herein, the "secondary particle size of fumed metal oxides refers to the final size of the congregated particles, and includes both aggregates and, when present, agglomerates. The secondary particle size of fumed metal oxides may be measured using light scattering analysis, to obtain the volume average secondary particle size. Devices Suitable for measuring secondary particle sizes are known in the art. Aggregates are clusters of two or more primary particles that are either impossible or very difficult to break down using dispersing devices. The primary particles of an aggregate are sintered together. Agglomerates are comprised of two or moreaggregates that are joined together loosely. In an agglomerate, the aggregated particles may be held together by electrostatic forces and Van der Waals forces. Agglomerates form when fumed metal oxides are produced. Agglomerates may be broken down to smaller agglomerates and aggregates, for example, upon exposure to conditions sufficient to form a fumed metal oxide dispersion.

[0125] Some P1 particles, have 3-dimensional branching structures, this can be referred to as a fractal shape which can result in particles with large aspect ratios. Fractal shape are aggregates of primary particles that have 3-dimensional branching. Preferably, the inorganic nanoparticles P1 have a fractal shape.

[0126] Preferably, the total surface area of the inorganic particles P1 in the CIS ranges from 50-99.95%, preferably from 60%-99.92%, more preferably from 70%- 99.9% based on total surface area of P1 plus P2.

[0127] METHODS OF MAKING THE IES and / or CIS

[0128] The CIS can be cast from waterborne slurry which is environmentally more desirable and sustainable or can be cast from solvent-based slurry depending on the composition of the electrode slurry. Having the same binder resin or miscible binder resins in the CIS and the corresponding electrode is preferred although not necessary.

[0129] A miscible polymer composition is a polymer blend that exhibits a single glass transition temperature value which typically lies intermediate between the glass transition temperatures of the individual polymeric components. Miscibility is said to exist when a mixture of two or more polymers results in a material exhibiting a single, well defined glass transition temperature, according to ASTM E1356-08(2014).

[0130] The IES can be casted concurrently in a multi-layer casting such as disclosed in US 11,133,562 to produce an in situ composite separator on to the electrode and used for application in electrochemical cells.

[0131] The IES could be fabricated by casting the separator slurry directly onto a wet electrode slurry or by powder coating of powder separator composition onto a powder electrode composition.

[0132] The separator slurry or separator powder composition may further contain effective amounts of other additives, including but not limited to fillers, leveling agents, anti-foaming agents, pH buffers, and other adjuvants typically used in formulation.

[0133] The invention relates to a concurrent casting process for forming an integrated electrode separator assembly comprising the steps of: a. forming an electrode pre-mix slurry comprising either a cathode slurry or an anode slurry, wherein the electrode pre-mix slurry comprises active material and at least one binder resin A, said electrode pre-mix slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C; b. forming a composite in-situ separator slurry comprising P1 and P2 and at least one binder resin B, said composite in-situ separator slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C; c. casting the electrode pre-mix slurry onto a current collector to form a wet electrode; d. forming a composite in-situ separator (CIS) by casting the composite in-situ separator slurry onto the at least one wet electrode formed in step c to form an assembly; and e. drying said assembly, to form an integrated electrode separator.

[0134] The wet electrode of c is not dried until after the casting of the composite in- situ separator slurry onto the wet electrode.

[0135] Binder resin A used for the electrode pre-mix slurry may be the same or different from binder resin B used for the composite in-situ separator slurry.

[0136] In an embodiment of the invention relates to a dual-slot die-casting process in which steps c) and d) are combined into a single operation wherein an electrode pre-mix slurry and the separator slurry are cast concurrently onto a current collector and dried to form an integrated electrode separator.

[0137] The invention further relates to using a dry process, more specifically electrospray process, for forming an integrated electrode separator assembly comprising the steps of:a. forming a powdery electrode mixturecomprising a powdery cathode mixture or a powdery anode mixture, said powdery electrode mixture comprises at least one binder resin A and active material; b. forming a powdery composite in-situ separator mixture comprising P1, P2, and at least one binder resin B; c. coating the powdery electrode mixture onto a current collector to form an electrode; d. forming composite in-situ separator (CIS) by coating powdery composite in-situ separator mixture directly onto the electrode of step c to form an assembly; and e. heating and / or compressing the assembly, to form an integrated electrode separator.

[0138] Binder resin A used for the powdery electrode mixture may be the same or different from binder resin B used for the powdery composite in-situ separator mixture.

[0139] By powdery is meant in powder form.

[0140] EXAMPLES

[0141] Test Materials and Methods:

[0142] Fumed Oxides (Alumina and Silica). Fumed silica - volume average secondary particle size is 50 - 300 nm, a surface area of 30 - 450 m2 / g. Fumed alumina volume average secondary particle size is 50 - 300 nm, a surface area of 30 - 450 m2 / g. Fumed alumina is Aerodisp® and Aeroxide® by Evonik.

[0143] Aluminum Oxide average particle size is 1-10 μm, a surface area of 1-10 m2 / g. Aluminum Oxide is Product #26R-8S10 from Inframat Advanced Material.

[0144] Incellion® EL 1061 is waterborne acrylic binder available from Arkema Inc. with MFFT below 25 °C. Kynar® LBG-2200 ("LBG-2200") and Kynar® HSV900(by Arkema) ("HSV900") is PVDF binder.

[0145] Density of composite was calculated by dividing the weight over volume of a specific sample. First composite was cast on an aluminum foil or copper foil, then a sample having 1.33 cm2surface area was made by stamp cutting of the castcomposite. The thickness of sample was measured with micrometer having accuracy of 0.1 micron. The weight of composite was measures using 5 decimal point analytical balance.

[0146] The porosity of separator can be obtained using: the equation %Porosity = [ 1 - (film density(from microtoming) / solid density)]*100.

[0147] electrochemical performance was evaluated using Arbin LBT21 (from Arbin Instruments) at 25 °C.

[0148] The aqueous slurry composition was prepared using a Thinky ARE-310 mixer. Five 6.5 mm zirconium beads are added into the 125ml Thinky jar. The aluminum oxide dispersion (Aerodisp W-640 ZX provided by Evonik) and the (1.5 wt%) CMC aqueous solution (BVH9 CMC provide by Ashland) are added to the jar and undergoes mixing in the Thinky at 2000 rpm for 2 minutes. Acrylic latex of Incellion-EL 1061 (acid functionalized acrylic / styrene copolymer available from Arkema Inc.) is added into the jar and it is mixed for 2000 rpm for another 2 minutes. PVDF latex of Kynar®LBG-2200LX ("LBG-2200") (Provided by Arkema Inc.) is added and mixed for 2000 rpm for 4 minutes. The PAA available from Aldrich having molecular weight of 3,000,000 Dalton.

[0149] The aqueous slurry compositions are tabulated in the tables below. Additional components may include thickeners or dispersant / surfactants such as Pluronic or IPA (Isopropyl alcohol).

[0150] Generally the composition for the composite in-situ separator falls within the following: fumed Aluminum Oxide 1-40wt%; Aluminum Oxide 1-95 wt%; Incellion-EL 1061 or LBG-2200 (Binder) 1 - 30 wt.%;Example 1-5

[0151] The separator slurry formulation was prepared using a THINKY ARE-310 mixer. Five 6.5 mm zirconium beads are added into a High molecular weight polyethylene (HMWPE) 125mL jar. The aluminum oxide and thickener are added to the jar and undergoes mixing in the THINKY for 2000 rpm for 2 mins. Fumedaluminum oxide is then added and is mixed for 2000 rpm for 2 minutes. The binder is added and mixed for 2000 rpm for 2 minutes. The produced slurry has an excellent fluidity with no visible aggregation.

[0152] The separator slurry was then cast on copper foil of 9-10 μm thick and paced in a conventional oven at 130 C for 20 min. The characteristics (thickness, porosity, and resistivity) of the separator slurry are tabulated in the table-1.Table-1 below contains the detailed formulation examples of separator of examples 1 to 5. CMC and PAA were used as thickeners.Table-1: Characteristics of separator compositions

[0153] In all 5 examples of table 1 the resistivity exceeded 1000 MΩ as measured by ohmmeter (maximum limit of the equipment). "1061" is Incellion® El 1061.

[0154] Example 6.

[0155] A typical graphite anode formulation is fabricated using the formulation : Graphite (92.8wt. %); SuperP (Carbon Black) (2wt.%); Incellion® EL 1061 (Binder) (4 wt.%); CMC (Thickener) (1.2 wt.%)

[0156] The anode slurry was prepared using a THINKY ARE-310 mixer. Seven 6.5 mm zirconium beads are added into a HMWPE 125mL jar. The graphite and carbon black are added to the jar. CMC is added to the jar in 4 sequential steps, where it undergoes mixing in the THINKY for 2000 rpm for 2 minutes in between the steps. Binder is added and is mixed for 2000 rpm for 2 minutes.

[0157] The anode slurry was casted onto a copper current collector, followed by casting of the separator slurry (from formulation of table 1- example 1) on top ofthe wet anode coating. The wet-on-wet casted slurries was then dried at 130°C for 20 minutes to produce the IES.

[0158] The electrochemical performance of the IES was evaluated in 2032 Graphite / NMC622 coin cells on Arbin LBT21 at 25 °C. The 2032 cells were assembled by laminating a piece of NMC622 cathode (typical cathode example 7) with the IES. An electrolyte containing IM LiPF6in ethylene carbonate and diethyl carbonate was used.

[0159] To study the effect of fast charging on the longevity, the cells underwent fast charging cycle 4C followed by a discharge cycle at 0.5C. Every 47thcycle, a capacity check cycle was performed for 3 cycles at 0.1C to determine the state of health of the cells and irreversible capacity loss from fast charge abuse. Cycles 49 to 51 are averaged to obtain the 50thcycle value. The voltage window is 3 - 4.2V. For the purpose of comparison, 2032 coin cells based on Graphite / NMC622 using a free-standing separator Celgard 2500 (from Celgard). were assembled. Control is the same anode as the inventive sample except a free-standing separator, Celgard 2500, was used instead of the inventive separator.

[0160] The Table-2 below tracks the capacity retention of the batteries determined by the capacity check cycles.Table-2 percent of capacity retention of batteries measure at C / 10 every 50 cycles

[0161] This shows that the invention provides longer life and higher tolerance to fast charge abuse. The control failed between the 350th-400thcycle whereas the inventive battery is still viable at 500thcycle. Once a lithium-ion battery falls below 80% capacity retention, the battery has reached its end of life.

[0162] Example 7

[0163] A typical cathode slurry is fabricated using the typical cathode formulation NMC622 (Active material) (97wt.%); SuperP (Carbon Black) (1.5wt.%); PVDF (Binder) (1.5wt.%) and the process below.

[0164] PVDF is dissolved in NMP at ambient temperature at 8% wt.% concentration. The formulation is prepared using a Thinky ARE-310 mixer. The PVDF and carbon black are added to a Thinky cup and are mixed for two minutes, two times, at 2000 RPM for a total of four minutes. NMP is added to the cup and mixed for four minutes, three times, at 2000 RPM for a total of twelve minutes. Active material is added to the cup and mixed for one minute, two times at 2000 RPM. The remaining aliquots of NMP are added to the active material slurry and mixed for one minute at 2000 RPM in between each addition.

[0165] The resulting electrode slurry was cast onto aluminum foil using a doctor blade. The electrode was dried in an oven at 120°C to evaporate NMP. The active material loading of the NMC622 cathode was llmg / cm2.

[0166] Example 8. Standard charge

[0167] Following the procedure described in example 6, the electrochemical performance of the IES was evaluated in 2032 Graphite / NMC622 coin cells on Arbin. The IES was produced with the same formulation and same separator slurry composition as Example 6.

[0168] The capacity retention of cell made with IES and control cells were evaluated using charge and discharge cycle at 0.5C for 1000 cycle to determine the state of health of the battery over operation. The voltage window is 3 - 4.2V. As control, 2032-coin cells were assembled using example 6 anode and standardNMC622 cathode example 7 plus a free-standing separator Celgard 2325 were assembled.

[0169] Table-4 shows the percent of capacity retentions for control- 2 (average over 2 replica) and IES-2 (average over 4 replica) of the 2032 batteries over long cycling. Passing is 80% or above.Table-4: Percent of average capacity retentions at every 250 cycles

[0170] Comparative Example 9-10.

[0171] Comparative examples of composite in-situ separator compositions are prepared according to the method of example 1 with the compositions provided in table 5. Example 9 uses only fumed alumina (P1) which requires a high amount of binder resin to prepare adequate films. Large amounts of binder are necessary due to the high surface area of P1, the film will not form. The data in table-5 shows that the resultant IES was not sufficiently resistive as compared to the invention.

[0172] Example 10 uses only aluminum oxide particles of P2, the resultant IES does not exhibit sufficient resistivity.

[0173] Examples 9 and 10 were used to prepared batteries. The batteries made using examples 9 and 10 shorted due to insufficient resistivity.

[0174] Table-5: Comparative examples; Characteristics of specific composite in- situ separator compositions. Binder 1061 is Incellion® 1061

[0175] Example 11

[0176] IES of Anode / CIS made following procedure described in example 6, the electrochemical performance of the IES was evaluated in 2032 Graphite / NMC622 coin cells on Arbin. The IES was produced with the same formulation and same separator slurry composition as Example 6.

[0177] The fast charge capacity retention of cell made with IES and control cells were evaluated using 15C charge and 0.2C discharge for 3 cycles, followed by 3 cycles of 0.2C charge and 0.2C discharge to determine state of health of battery after exposure to fast charge. The voltage window is 3 - 4.2V. As control, 2032- coin cells were assembled using example 6 anode and standard NMC622 cathode example 7 plus a free-standing separator Celgard 2500 were assembled.

[0178] After exposure to 15C charge cycles as described above, the state of health for IES cell remains 97% while control cell retained only 83%.

[0179] Example 12-13

[0180] The separator slurry formulation was prepared using a THINKY ARE-310 mixer. Five 6.5 mm zirconium beads are added into a High molecular weight polyethylene (HMWPE) 125mL jar. HSV900 is dissolved in NMP at ambient temperature at 8% wt.% concentration. The aluminum oxide and HSV900 are added to the jar and undergoes mixing in the THINKY for 2000 rpm for 2 mins. Optionally, fumed aluminum oxide is then added for 2000 rpm for 2 minutes. The produced slurry has excellent fluidity with no visible aggregation.

[0181] The separator slurry was then cast on aluminum foil of 15 μm thick and placed in a conventional oven at 130 C for 20 min. The characteristics (thickness, porosity, and resistivity) of the separator slurry are tabulated in the table-6.Table-6 below contains the detailed formulation examples of separator of examples 12 and 13.Table-6: Characteristics of specific separator compositions

[0182] In the examples of table 6 the resistivity exceeded 1000 MΩ by ohmmeter (maximum limit of the equipment).

[0183] Various embodiments of the invention have been described in fulfillment of the various objects of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention.Numerous modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of this invention.

Claims

CLAIMS1. An integrated electrode separator comprising an electrode and a composite in- situ separator ("CIS"), wherein the separator comprises a) a binder resin, b) inorganic particles P1, and c) second inorganic particles P2, said integrated electrode separator having an open porous structure, wherein the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron.

2. The integrated electrode separator of claim 1, wherein the inorganic particles P1 are anionic and have a specific surface area of between 50 m2 / g and 1000 m2 / g.

3. The integrated electrode separator of claim 1, wherein the inorganic particles P1 are anionic and have a specific surface area of between 50 m2 / g and 700 m2 / g.

4. The integrated electrode separator of claim 1, wherein the second inorganic particles P2 are electronically nonconductive and have a specific surface area of between 0.1 m2 / g and 20 m2 / g.

5. The integrated electrode separator of any one or more of claims 1 to 4, wherein the binder resin has a solution viscosity of between 100 cp and 5,000 cp at 5 wt % in NMP, at 25°C and 10 sec-1.

6. The integrated electrode separator of any one or more of claims 1 to 4, wherein the binder resin has a solution viscosity of between 100 cp and 3,000 cp at 5 wt % in NMP, at 25°C and 10 sec-1.

7. The integrated electrode separator of any one or more of claims 1 to 4, wherein the binder resin has a solution viscosity of between 100 cp and 5000 cp at 2 % in water, at 25°C and 10sec-1.

8. The integrated electrode separator of any one or more of claims 1 to 4, wherein the binder resin has a solution viscosity of between 100 cp and 3000 cp at 2 % in water at 25°C and 10sec-1.

9. The integrated electrode separator of any one or more of claims 1 to 8, wherein the binder resin is selected from the group consisting of carboxymethyl cellulose CMC, poly vinyl alcohol (PVOH), polyacrylic acids (PAA), polyvinyl pyrrolidone (PVP), polyvinylidene fluoride (PVDF), PVDF-copolymers, poly ethylene-tetrafluoride ethylene PETFE, Polyvinyl fluoride (PVF), poly acrylates, poly methacrylates, polystyrene, polyesters, polyamides, poly acrylonitrile, poly acrylamide, and their copolymers and combinations thereof.

10. The integrated electrode separator of any one or more of claims 1 to 9, wherein the ratio of binder resin to total inorganic particles (P1 and P2) in the CIS is from 1 :99 to 40:60 based on weight percent.

11. The integrated electrode separator of any one or more of claims 1 to 9, wherein the ratio of binder resin to total inorganic particles (P1 and P2) in the CIS is from 2:98 to 30:70 based on weight.

12. The integrated electrode separator of any one or more of claims 1 to 9, wherein the weight ratio of binder resin to total inorganic particles (P1 and P2) in the CIS is from 2 parts:98 parts to 10 parts:90 parts based on weight.

13. The integrated electrode separator of any one or more of claims 1 to 12, wherein the amount of P1 is at least 5wt% based on the total wt of P1 plus P2 and up to 50wt% based on total wt of P1 and P2.

14. The integrated electrode separator of any one or more of claims 1 to 13, wherein the interface between the separator and electrode is diffused.

15. The integrated electrode separator of any one or more of claims 1 to 14, wherein the CIS has from 20 % to 80 % open pores, preferably 20 to 60% open pores.

16. The integrated electrode separator of any one or more of claims 1 to 15, wherein average thickness of the CIS is greater than 5 microns and less than 40 microns as measured by SEM-EDX.

17. A method for forming an integrated electrode separator assembly comprising the steps of: a) forming an electrode pre-mix slurry, wherein the electrode pre-mix slurry comprises active material and at least one binder resin, said electrode pre-mix slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C; b) forming a composite in-situ separator slurry comprising P1 and P2 and at least one binder resin, said composite in-situ separator slurry having a slurry viscosity greater than 1000 cp at 10s- 1at 25°C;c) casting the electrode pre-mix slurry onto a current collector to form a wet electrode; d) forming a composite in-situ separator (CIS) by casting the composite in-situ separator slurry onto the at least one wet electrode formed in step c) to form an assembly; and e) drying said assembly, to form an integrated electrode separator, wherein the number average secondary particle size of P1 is less than 0.5 micron, and the number average particle size of P2 is greater than 1.0 micron and wherein the binder resin of a) can be the same of different from the binder resin of b).

18. The method of claim 17 wherein the electrode pre-mix slurry and composite in-situ separator slurry are both water-born slurries.

19. The method of claim 17 wherein the electrode pre-mix slurry and composite in-situ separator slurry are both solvent-born slurries.

20. The method of claim 17, wherein the electrode slurry and composite in-situ separator slurry are cast concurrently onto a current collector and then dried to form an integrated electrode separator.

21. The method of any one or more of claims 17-20 wherein the binder resin of the electrode pre-mix slurry and the binder resin of the composite in-situ separator slurry are the same binder resin or are miscible binder resins.

22. The method of any one or more of claims 17-20 wherein the interface between the electrode and separator is diffuse.

23. A method for forming an integrated electrode separator assembly comprising the steps of: a) forming a powdery electrode mixture, said powdery electrode mixture comprises at least one binder resin A and active material; b) forming a powdery composite in-situ separator mixture comprising P1, P2, and at least one binder resin B; c) coating the powdery electrode mixture onto a current collector to form an electrode;d) forming composite in-situ separator (CIS) by coating powdery composite in-situ separator mixture directly onto the electrode of step c to form an assembly; and e) heating and / or compressing the assembly, to form an integrated electrode separator, wherein the binder resin A can be the same of different from the binder resin B.

24. The method of claim 23, wherein the electrode mixture plus composite in-situ separator mixture is heated and compressed after electrospraying the composite in- situ separator powder mixture onto the electrosprayed powdery electrode mixture as a finished product to form the IES component, wherein the electrode mixture is not heated or compressed prior to the electrospraying of the composite in-situ separator powder mixture.

25. The method of claim 23, wherein the electrode is heated and compressed to form an electrode layer, the powdery composite in-situ separator mixture is then applied to the electrode layer and the electrode plus CIS are heated and compressed.

26. The method of any one of claims 23-25 wherein the binder resin A and the binder resin B are the same binder resin or are miscible binder resins.

27. The method of any one of claims 23 to 26, wherein the interface between the electrode and CIS is diffuse.

28. A battery comprising the IES of any one of claims 1 -16.

29. A battery comprising the IES of any one of claims 1 -16, wherein the state of health of the battery is greater than 80% when repeatedly charged at 4C for 500 cycles, preferable greater than 80% when repeatedly charged at 4C for 700 cycles, more preferably greater than 80% when repeatedly charged at 4C for 1000 cycles.

30. The battery of claim 29, wherein the thickness of the composite in situ separator is less than 40 microns.

31. A battery comprising an IES component of any one of claims 1 -16wherein the state of health of the battery is greater than 80% when it is repeatedly charged at C / 2 for 500 cycles, preferable greater than 80% when repeatedly charged at C / 2 for 700 cycles, more preferably greater than 80% when repeatedly charged at C / 2 for 1000 cycles.

32. The battery of claim 31, wherein the thickness of the composite in situ separator is less than 40 microns.

33. The battery of any one of claims 29-32, wherein the only separator present is the composite in-situ separator.

34. The battery of any one of claims 29-32, wherein there is no polyolefin separator.

35. The battery of any one of claims 29-32, wherein the porosity of the IES component is greater than 20%, preferably greater than 30%.

36. A battery comprising the IES of any one of claims 1 -16, wherein the state of health of the battery is greater than 90% when repeatedly charged at 15C for 5 cycles, preferable greater than 80% when repeatedly charged at 15C for 100 cycles.

37. The battery of claim 36, wherein the thickness of the composite in situ separator is less than 40 microns.

38. The battery of any one of claims 28-37, wherein the battery comprises one IES comprising an anode and wherein the cathode is not part of an IES.

39. A battery comprising the IES of claim 1, wherein the battery comprises one IES comprising an anode and wherein the cathode is not part of an IES, wherein the state of health of the battery is greater than 90% when repeatedly charged at 15C for 5 cycles, preferable greater than 80% when repeatedly charged at 15C for 100 cycles.

40. The battery of claim 39, wherein the thickness of the composite in situ separator is less than 40 microns.

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