Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0568—Liquid materials characterised by the solutes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a composite electrolyte comprising a solid-liquid electrolyte in the form of a gel for use in electrochemical devices particularly in primary or secondary batteries, supercapacitors, electro-chromic displays or solar cells.
• the present invention also relates to electrochemical devices comprising the composite electrolyte element and the method for their preparation.
• Alkali metal batteries in particular lithium-ion batteries are known. They are widely used in portable electronic devices, cameras, electric tools, electric vehicles and the like.
• “soggy-sand” electrolytes are also known.
• “Soggy-sand” electrolytes are defined as solid-liquid composite electrolytes comprising inorganic oxide, such as AI2O3, T1O2, S1O2, dispersed in a non-aqueous liquid electrolyte salt solution. At certain regimes of volume fractions of the oxide, which is typical to the components of the electrolytic system, the liquid electrolyte transforms into a gel electrolyte.
• the use of“soggy-sand” electrolytes greatly reduces the risk of electrolyte leakage which may occur with liquid electrolytes and enhance the safety performance with their thermal stability and non- flammable inorganic characteristics.
• “soggy-sand” electrolytes may exhibit ion transport and ionic conductivity higher than the starting liquid electrolytes and also higher than solid electrolytes.
• EP1505680A2 disclose a battery comprising a non-aqueous electrolyte comprising an ionically conducting salt, a non-aqueous, anhydrous solvent and an oxide, such as S1O2, having the average particle size lower than 5 pm, the oxide being present in the electrolyte in an amount from 20 to 50 vol% (that is, above 44% by weight when the oxide is S1O2).
• US9722275 discloses a battery cell comprising (a) an anode; (b) a cathode structure; and (c) an ionically conductive protective layer on a surface of the anode and interposed between the anode and the cathode structure.
• the protective layer comprises a porous membrane having pores therein and a“soggy sand” soft matter phase disposed in at least one of the pores, wherein the soft matter phase comprises oxide particles dispersed in a non-aqueous alkali, alkaline, or transition metal salt solution.
• The“soggy sand” soft matter phase thus impregnates the porous membrane.
• the conductive protective layer may also serve as a separator/electrolyte layer disposed between the anode and the cathode structure.
• the material used as the porous membrane is not a critical factor in the preparation of the protective layer and examples are provided using polyethylene-based microporous layers.
• separator/electrolyte layers having increased stability can be obtained when a layer of a “soggy-sand” solid-liquid electrolyte comprising precipitated silica is provided on at least one surface of a non-woven layer.
• a non-woven porous layer in combination with a solid-liquid electrolyte also provides access to an advantageous method for the preparation of pouch batteries which comprises the injection of the solid-liquid electrolyte to a preformed pouch comprising the non-woven material.
• FIG. 1 shows a schematic view of a mono- and stack type pouch cell.
• FIG. 2 illustrates a schematic view of mono pouch cell using solid-liquid electrolyte with non-woven layer.
• FIG. 3 shows the cycle performance of mono cells of Example 1 and Comp. Example 1.
• FIG. 4 shows the thermal exposure safety test of stack type pouch cells of Example 2 and Comp. Example 2
• the first object of the present invention is a composite electrolyte for use in alkali metal batteries comprising:
• non-woven layer having a first and a second surface
• solid-liquid electrolyte layer comprises:
• non-woven is used herein to refer to common fabric-like materials made from short fibers and long fibers, bonded together by chemical, mechanical, heat or solvent treatment. Non-woven materials are porous materials.
• the nature of the fiber composing the non-woven layer is not limiting.
• Suitable non-woven materials for use in the composite electrolyte of the invention may be made of inorganic or organic fibers.
• inorganic fibers mention may be made of glass fibers.
• organic fibers mention may be made of cellulose or rayon fibers, carbon fibers, polyolefins fibers such as polyethylene or polypropylene fibers, poly(paraphenylene terephthalamide) fibers, polyethylene terephthalate fibers, polyimide fibers or any other polymer that can be fabricated in a fiber form.
• a solid-liquid electrolyte layer is provided on at least one surface of the non-woven layer.
• the solid-liquid electrolyte layer is provided on each surface of the non-woven layer.
• the non-woven layer has a thickness comprised between 5 and 100 pm, preferably between 10 and 80 pm, more preferably between 10 and 50 pm.
• Non-limiting examples of suitable non-woven layers are those supplied by Nippon Kodoshi Corp. (Japan) under trade name TF4035.
• the one or two solid-liquid electrolyte layer(s) typically has a thickness which does not exceed 100 pm.
• the solid-liquid electrolyte layer(s) may have a thickness of at least 5 pm, preferably of at least 8 pm.
• the composite electrolyte of the invention has a total thickness, meant as the thickness of the non-woven layer and of the one or two solid-liquid electrolyte layer(s), which is generally greater than 10 pm, even greater than 15 pm. Preferably, the total thickness does not exceed 300 pm.
• the composite electrolyte of the invention has a thickness of from 25 to 120 pm.
• the composite electrolyte of the invention comprises a non-woven layer having a thickness from 15 to 40 pm and a solid-liquid electrolyte layer provided on each surface of the non-woven layer, each solid-liquid electrolyte layer having a thickness of from 8 to 35 pm.
• the solid-liquid electrolyte layer comprises at least one ionically conducting salt, at least one organic carbonate-based solvent, and precipitated silica.
• Suitable ionically conducting salts are selected from the group consisting of:
• RV is selected from the group consisting of F, CF3, CHF 2 , CH 2 F, C 2 HF 4J C 2 H 2 F 3 , C 2 H 3 F 2 , C 2 F 5 , C 3 F 7J C 3 H 2 F 5 , C 3 H 4 F 3J C 4 F 9J C 4 H 2 F 7 ,
• the at least one ionically conducting salt is preferably selected from the group consisting of LiPF6, LiBF 4 , UCI0 4 , lithium bis(oxalato)borate ("LiBOB"), LiN(S0 2 F) 2 , LiN(CF 3 S0 2 ) 2 , LiN(C 2 F 5 S0 2 )2, Li[N(CF 3 S02)(RFS02)]n with RF being C2F5, C 4 F 9 , CF 3 OCF2CF2, LiAsFe, LiC(CF 3 S02)3 and mixtures thereof. More preferably, the ionically conducting salt is LiPF6.
• the ionically conducting salt is preferably dissolved in the organic carbonate-based solvent in a concentration between 0.5 and 5.0 molar, more preferably between 0.8 and 1.5 molar, still more preferably of 1.0 molar.
• Non-limiting examples of suitable organic carbonate-based solvents include unsaturated cyclic carbonates and acyclic carbonates.
• Suitable unsaturated cyclic carbonates include cyclic alkylene carbonates, e.g. ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, fluoroethylene carbonate and fluoropropylene carbonate.
• EC ethylene carbonate
• PC propylene carbonate
• butylene carbonate fluoroethylene carbonate
• fluoropropylene carbonate fluoropropylene carbonate.
• a preferred unsaturated cyclic carbonate is ethylene carbonate.
• Suitable acyclic carbonates include dimethylcarbonate (DMC),
• DEC diethylcarbonate
• EMC ethylmethylcarbonate
• fluorinated acyclic carbonates such as those represented by the formula:
• R I -0-C(0)0-R 2 wherein R1 and R2 are independently selected from the group consisting of CFI 3 , CFhCFh, CFhCF CFh, CFI(CFI 3 )2, and CFhRf where Rf is a C1 to C3 alkyl group substituted with at least one fluorine atom, and further wherein at least one of R1 or R2 contains at least one fluorine atom.
• Suitable solvents may additionally comprise an ester component selected from the group consisting of propyl propionate (PP), ethyl propionate (EP) and the fluorinated acyclic carboxylic acid esters of formula: R3-C(0)0-R 4 , wherein R3 is selected from the group consisting of CH3, CH2CH3,
• R 4 is independently selected from the group consisting of CH3, CH 2 CH3, CFhCFhCFh, CFI(CFl3)2, and CFI 2 Rf, where R5 is a C1 to C3 alkyl group which is optionally substituted with at least one fluorine atom, and R3 is a C1 to C3 alkyl group substituted with at least one fluorine, and further wherein at least one of R3 or R 4 contains at least one fluorine and when R3 is CF 2 H, R 4 is not CH.
• the at least one organic carbonate-based solvent is a mixture of at least one acyclic carbonate and at least one unsaturated cyclic carbonate. More preferably, the at least one organic carbonate-based solvent is a mixture of ethylene carbonate and ethylmethylcarbonate.
• the mixture of at least one acyclic carbonate and at least one unsaturated cyclic carbonate comprises the at least one unsaturated cyclic carbonate and the at least one acyclic carbonate in a ratio from 1 :4 to 1 :1 by volume, more preferably of from 1 :2.5 to 1 :1 by volume, still more preferably of 1 :1 by volume.
• the solid-liquid electrolyte comprises precipitated silica.
• precipitated silica it is meant an amorphous silica that is prepared by precipitation from a solution containing silicate salts (such as sodium silicate), with an acidifying agent (such as sulfuric acid).
• Precipitated silica used in the invention may be prepared by implementing the methods described in EP396450A, EP520862A, EP670813A, EP670814A, EP762992A, EP762993A, EP917519A, EP1355856A,
• the precipitated silica used in the composite electrolyte of the present invention has a median particle size comprised in the range of from 3.0 pm to 80.0 pm.
• the median particle size may be determined by laser diffraction using a MALVERN (MasterSizer 2000) particle sizer, employing the Fraunhofer theory.
• the analysis protocol includes a first full deagglomeration of the precipitated silica sample to be carried out before the laser diffraction determination.
• Time to reach a stable median particle size with such protocol is typically around one hundred seconds.
• the precipitated silica median particle size is in the range from 3.0 to 80.0 pm, more preferably from 3.0 to 60.0 pm, still more preferably from 3.0 to 20.0 pm. In some embodiments, the median particle size may be greater than 5.0 pm, even greater than 6.0 pm.
• the precipitated silica is characterized by a BET specific surface area of from 100 to 650 m 2 /g.
• the precipitated silica has a BET specific surface area from 100 to 280 m 2 /g.
• the precipitated silica typically has a BET specific surface of at least 110 m 2 /g, in particular of at least 120 m 2 /g.
• the BET specific surface generally is at most 270 m 2 /g, in particular at most 260 m 2 /g.
• the precipitated silica has a BET specific surface area of from 300 to 650 m 2 /g.
• the precipitated silica typically has a BET specific surface of at least 310 m 2 /g, in particular of at least 330 m 2 /g.
• the BET specific surface is determined according to the Brunauer- Emmett-Teller method described in The Journal of the American Chemical Society, Vol. 60, page 309, February 1938, and corresponding to the standard NF ISO 5794-1 , Appendix E (June 2010).
• Suitable precipitated silicas may for example have:
• Preferred precipitated silicas used in the composite electrolyte of the present invention are characterized by having a Bound Water Content of at least 2.5 wt%, more preferably of at least 4.0 wt%.
• the Bound Water Content is determined by the difference between the Loss on Ignition at 1000 °C (measured according to DIN 55921 , ISO 3262/11 , ASTM D 1208) and the Moisture Loss measured at 105 °C (measured according to ISO 787/2, ASTM D 280); this value is characteristic of the underlying structure of the silica.
• the precipitated silica used in the present invention preferably exhibits a pH of between 6.3 and 8.0, more preferably of between 6.3 and 7.6.
• the pH is measured according to a modification of standard ISO 787/9 (pH of a 5% suspension in water) as follows: 5 grams of precipitated silica are weighed to within about 0.01 gram into a 200 mL beaker. 95 mL of water, measured from a graduated measuring cylinder, are subsequently added to the precipitated silica powder. The suspension thus obtained is vigorously stirred (magnetic stirring) for 10 minutes. The pH measurement is then carried out.
• the precipitated silica used in the present invention has an aluminium content, calculated as aluminium metal, of more than 0.25 wt%, even more than 0.30 wt% with respect to the weight of the precipitated silica.
• the content of aluminium may conveniently be of at most 0.50 wt%.
• precipitated silica which could be used in the present invention are for instance Tixosil ® 43, Tixosil ® 68B, Tixosil ® 331 or Tixosil ® 365, all commercially available from Solvay.
• the amount of precipitated silica present in the solid-liquid electrolyte is such as to give the electrolyte a consistency of a gel.
• gel it is intended to denote a semi-rigid colloidal dispersion of a solid with a liquid to produce a viscous jelly-like product.
• the amount by weight of precipitated silica in the solid-liquid electrolyte is in the range from 1.0% to 25.0%, preferably from 1.0 to 15.0% relative to the total weight of the solid-liquid electrolyte.
• the solid-liquid electrolyte exhibits a sufficiently low viscosity which makes it suitable for use in the production of pouch batteries by injection.
• the viscosity may be in the range from 1.0 to 600 Pa.s at 25°C under a shear rate of 1 s -1 .
• the viscosity may conveniently be in the range from 1.5 to 600 Pa.s, from 2.0 to 600 Pa.s, even from 4.0 to 600 Pa.s, still from 5.0 to 500 Pa.s at 25°C under a shear rate of 1 s -1 .
• the solid-liquid electrolyte comprises precipitated silica having a BET specific surface of from 100 to 270 m 2 /g in an amount by weight in the range from 1.0% to 8.5% relative to the total weight of the electrolyte.
• the amount by weight of precipitated silica may be advantageously from 2.0% to 8.0% relative to the total weight of the electrolyte, preferably from 3.0% to 8.0.
• the solid-liquid electrolyte comprises precipitated silica having a BET specific surface from 300 to 650 m 2 /g in an amount by weight in the range of from 2.0% to 18.0% relative to the total weight of the electrolyte.
• the solid-liquid electrolyte is characterized by high mechanical properties, so that the spreading of the solid-liquid electrolyte on the surface of the non-woven porous layer can be conveniently performed.
• the viscosity of the solid- liquid electrolyte of the second embodiment may conveniently be in the range from 600 to 10000 Pa.s at 25°C under a shear rate of 1 s -1 .
• the viscosity may even be in the range from 600 to 5000 Pa.s at 25°C under a shear rate of 1 s _1 , in some instances even in the range from 600
• the solid-liquid electrolyte comprises precipitated silica having a BET specific surface from 100 to 270 m 2 /g in an amount by weight in the range of from 8.5% to 15.0%, even from 9.0% to 15.0 relative to the total weight of the electrolyte.
• the solid-liquid electrolyte comprises precipitated silica having a BET specific surface from 300 to 650 m 2 /g in an amount by weight in the range from 18% to 25.0%, even from 19.0% to 25.0 relative to the total weight of the electrolyte.
• the solid-liquid electrolyte comprises:
• the precipitated silica has a BET specific surface of from 100 to 270 m 2 /g, and a median particle size from 3.0 to 80.0 pm. In some instances the median particle size may be greater than 5.0 pm, even greater than 6.0 pm.
• the solid-liquid electrolyte comprises:
• the precipitated silica has a BET specific surface from 100 to 270 m 2 /g, and a median particle size from 3.0 to 80.0 pm. In some instances the median particle size may be greater than 5.0 pm, even greater than 6.0 pm.
• the solid-liquid electrolyte can also conveniently contain at least one additive selected from the group consisting of:
• VC vinylene carbonate
• VEC vinyl ethylene carbonate
• FEC fluoroethylene carbonate
• F2EC difluoroethylene carbonate
• conductive coatings such as poly-thiophene, poly(3,4- ethylenedioxythiophene (PEDOT); - additional lithium salts, such as Li bis(trifluorosulphonyl)imide, lithium oxalyldifluoroborate;
• SEI solid electrolyte interphase
• TMSB tris(trimethylsilyl)borate
• TMSP tris(trimethylsilyl) phosphite
• PS 1 ,3-propane sultone
• PES prop-1-ene-1 ,3-sultone
• PFO-EC perfluoro-octyl-ethylene carbonate
• - passivizing agents such as hexafluoroisopropanol, succinic anhydride
• the composite electrolyte of the invention may be manufactured by any process known in the art.
• the composite electrolyte may, for instance, be prepared by means of a process wherein the solid-liquid electrolyte is coated on one or both surfaces of the non-woven layer using means known to the person skilled in the art of coating.
• the present invention provides an electronic device, in particular primary or secondary batteries, supercapacitors, electro-chromic displays or solar cells comprising the composite electrolyte as defined above. All definitions and preferences defined above for the composite electrolyte and its components equally apply to the electronic devices comprising the composite electrolyte.
• the electronic device may be an alkali metal battery.
• alkali metal battery is used herein to refer to lithium metal, lithium-ion and sodium-ion primary or secondary batteries.
• the alkali metal battery may be of any type, such as cylindrical, button, prismatic, or in the form of a pouch.
• the alkali metal battery comprises at least one positive electrode, at least one negative electrode and at least one composite electrolyte of the invention disposed between the positive and the negative electrodes.
• the inventive composite electrolyte not only provides spatial and electrical separation between the negative electrode and the positive electrode but also the electrolyte for the transfer of the ions.
• the composite electrolyte of the invention finds advantageous use in the preparation of pouch batteries.
• an additional object of the invention is a pouch battery comprising a composite electrolyte comprising a non-woven layer and a solid-liquid electrolyte provided on at least one surface of said non-woven porous layer.
• the solid liquid electrolyte in said pouch battery comprises:
• the solid liquid electrolyte in said pouch battery comprises:
• the solid-liquid electrolytes defined above are characterised by a viscosity which makes them suitable for being injected directly into a preformed pouch comprising at least one positive electrode, at least one negative electrode and at least one non-woven porous layer positioned between said negative and said positive electrodes, providing an efficient process for preparing the composite electrode and the battery assembly at the same time.
• the viscosity of the solid-liquid electrolyte at 25°C under a shear rate of 1 s _1 , is in the range of from 1 to 600 Pa.s, from 5 to 500 Pa.s.
• the invention therefore is also directed to a process for the manufacture of an alkali battery, preferably a lithium-ion battery, said process comprising: providing an assembly containing at least one positive electrode, at least one negative electrode and at least one non-woven layer positioned between the negative and the positive electrode, and injecting a solid- liquid electrolyte in the assembly so that a solid-liquid electrolyte layer forms on at least one surface of the non-woven layer, and sealing the assembly.
• a solid-liquid electrolyte layer is formed on each surface of the non-woven layer.
• the process may be applied both to the manufacture of a battery comprising one cell (monocell) as well as more than one cell in a so-called “stack”.
• a suitable number of non-woven layers are present between each positive and each negative electrodes in the stack.
• the present invention concerns lithium- or sodium- ion batteries (primary or secondary), preferably lithium-ion batteries, more preferably lithium-ion secondary batteries.
• Suitable compounds may be those of formula Li3-xM’ y M”2-y(J0 4 )3 wherein 0£x£3, 0£y£2, M’ and M” are the same or different metals, at least one of which being a transition metal, J0 4 is preferably P0 4 which may be partially substituted with another oxyanion, wherein J is either S, V, Si, Nb, Mo or a combination thereof. Still more preferably, compound EA1 is a phosphate-based electro-active material of formula Li(Fe x Mni -x )P0 4 wherein 0£x£1 , wherein x is preferably 1 (that is to say, lithium iron phosphate of formula LiFeP0 4 ).
• secondary battery preferably comprise:
• lithium typically existing in forms such as powders, flakes, fibers or spheres (for example, mesocarbon microbeads) hosting lithium;
• lithium silicides with high Li/Si ratios in particular lithium silicides of formula Li 44 Si;
• Non-Woven Layer TF4035 (TF4035) manufactured by Nippon Kodoshi Corp., Japan comprising rayon fibers and having thickness of 35 pm and a porosity of about 40% to 80%.
• Polyethylene layer porous polyethylene layer Celgard® PE having a thickness of 25 pm and a porosity of about 40% manufactured by Celgard LLC
• NCM622 LiNio.6Coo.2Mno.2O2, manufactured by L&F, South Korea
• Solef ® 5130 PVDF binder, manufactured by Solvay Specialty Polymers BTR918-2: Natural graphite manufactured by BTR
• SBR/CMC styrene-butadiene rubber/carboxymethyl cellulose binder
• Liquid electrolyte The electrolyte was prepared by simple mixing using magnetic stirrer. All components were added to one bottle and were mixed until providing a transparent solution. Firstly, lithium hexafluorophosphate (LiPFe) was dissolved in the solvent. The solvent was composed of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 3:7 v/v ratio and then 2 wt% vinylene carbonate (VC). Then 0.5 wt% 1 ,3-propane sultone (PS) was added as an additive. This electrolyte was used as a reference electrolyte.
• EC ethylene carbonate
• EMC ethyl methyl carbonate
• PS wt% vinylene carbonate
• Solid-liquid electrolyte All required components were added to one bottle and were mixed by hand shaking until forming a gel. The precipitated silica was dried and added to the liquid electrolyte in an inert atmosphere, so as to avoid traces of water in the final product. The bottle was sealed by Parafilm ® M (Bemis).
• Viscosity of the electrolyte compositions was measured using a Malvern Kinexus ultra+ rheometer (KNX2310 with CP1/60 SR2752 spindle) at 25°C under a shear rate of 1 s -1 .
• a solid-liquid electrolyte comprising 10 wt% of precipitated silica T331 (Electrolyte A in Table 1) was prepared as described in the General Procedure.
• a lithium-ion secondary battery configured as schematized in FIG. 2
• a natural graphite electrode having the following formulation was used as a negative electrode:
• Negative electrode formulation BTR918-2 + Super-P® + SBR/CMC
• Electrolyte A was coated on the surface of the anode.
• the non-woven layer TF4035 was placed over the layer formed by
• Electrolyte A was coated on the exposed surface of the non-woven layer.
• a natural graphite electrode having the following formulation was used as positive electrode:
• Positive electrode formulation NCM622 + Super-P® + 8% Solef® 5130 (95:3:2 by weight); electrode loading: 13.3 mg/cm 2 , 84-86 pm thickness; theoretical capacity: 172 mAh/g.
• the thickness of the composite electrolyte was 60 ⁇ 10 pm.
• Example 1 Battery A
• Comparative Example 1 Comparative Example 1
• SEI solid electrolyte interphase
• Battery A than the reference battery (Reference 1) as measured after 100 charge/discharge cycles, thus demonstrating the superior performances of a composite electrolyte with solid-liquid electrolyte and non-woven layer with respect to one using a porous polyethylene layer.
• a solid-liquid electrolyte comprising 4 wt% of T331 (Electrolyte C in Table 1) was prepared as described in the General Procedure.
• An assembly for a pouch cell comprising a negative electrode, a positive electrode and the non-woven layer TF4035 disposed between the positive and the Negative electrode, configured as schematized in FIG. 1 , was prepared.
• Negative electrode formulation BTR918-2 + Super-P® + SBR/CMC (97:1 :1 :1 by weight); electrode loading: 13.3 mg/cm 2 .
• Electrolyte (C) was injected in pouch cell using a syringe and sealed under vacuum.
• Battery C and Reference 2 were subjected to a formation step to form a solid electrolyte interphase between the electrolyte and the surface of the negative electrode. They were charged at a C-rate of C/10 for 3 hours at 25°C.
• Battery C and Reference 2 were then subjected to a thermal exposure test in the following conditions: heating up to 200°C with a heating rate of 5°C/min, hold for 60 min at 200°C in the explosion proof chamber.

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• 2019
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