WO2022194219A1 - 用于电池负极的复合固态电解质材料、负极片及全固态锂电池 - Google Patents

用于电池负极的复合固态电解质材料、负极片及全固态锂电池 Download PDF

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WO2022194219A1
WO2022194219A1 PCT/CN2022/081236 CN2022081236W WO2022194219A1 WO 2022194219 A1 WO2022194219 A1 WO 2022194219A1 CN 2022081236 W CN2022081236 W CN 2022081236W WO 2022194219 A1 WO2022194219 A1 WO 2022194219A1
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negative electrode
solid electrolyte
electrolyte material
solid
battery
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PCT/CN2022/081236
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English (en)
French (fr)
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历彪
郭姿珠
易观贵
张桐
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比亚迪股份有限公司
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    • 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
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • 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
    • 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
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
    • 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
    • H01M2300/0088—Composites
    • H01M2300/0094—Composites in the form of layered products, e.g. coatings

Definitions

  • the present application relates to the technical field of batteries, and in particular, to a composite solid-state electrolyte material, a negative electrode sheet and an all-solid-state lithium battery for a negative electrode of a battery.
  • the embodiments of the present application provide a composite solid electrolyte material, a negative electrode sheet, and an all-solid-state lithium battery for a battery negative electrode.
  • the composite solid electrolyte material can be At the same time, it has excellent electronic conductivity and ionic conductivity. It can improve the electrochemical performance of the negative electrode with a small amount of addition in the negative electrode, and will not significantly reduce the negative electrode capacity and reduce the battery energy density.
  • the first aspect of the embodiments of the present application provides a composite solid electrolyte material for a negative electrode of a battery, including a solid electrolyte body and a coating layer coated on the surface of the solid electrolyte body, and the material of the coating layer is It includes one or more of antimony, bismuth, antimony-bismuth alloy, antimony-lithium alloy, bismuth-lithium alloy, and antimony-bismuth-lithium alloy.
  • the composite solid electrolyte material for the battery negative electrode provided in the first aspect of the embodiment of the present application can endow the composite solid electrolyte material with good electronic conductivity and ionic conductivity by coating the above-mentioned specific coating layer on the surface of the solid electrolyte body. It is conducive to the formation of good contact between the composite solid electrolyte material particles and between them and the negative electrode active particles, so as to obtain a negative electrode sheet with higher density and less voids, and establish a good electronic path and ion path in it, and then It can help to improve the battery performance.
  • the working voltage of the all-solid-state lithium battery prepared from the negative electrode sheet is within the working voltage range.
  • the coating layer of the composite solid electrolyte material exists stably in at least one form of antimony-lithium alloy, bismuth-lithium alloy and antimony-bismuth-lithium alloy, and does not participate in the electrochemical reaction of intercalation/delithiation, mainly to conduct lithium ions and
  • the role of electrons is relatively stable in nature and does not change in volume, which can improve the cycle stability of the battery.
  • the thickness of the coating layer is 5 nm-1 ⁇ m.
  • the thickness can achieve a uniform coating effect without reducing the ionic conductivity of the composite solid-state electrolyte material.
  • the mass ratio of the coating layer is 0.5%-30%.
  • the mass ratio can ensure that the thickness of the coating layer is appropriate and the coating integrity is high, and both high electronic conductivity and good ionic conductivity are better taken into account.
  • the ionic conductivity of the composite solid-state electrolyte material at room temperature is in the range of 1 ⁇ 10 -6 S ⁇ cm -1 to 2.5 ⁇ 10 -2 S ⁇ cm -1 .
  • the electronic conductivity of the composite solid-state electrolyte material at room temperature is in the range of 1 ⁇ 10 ⁇ 3 S ⁇ cm ⁇ 1 to 2.5 ⁇ 10 4 S ⁇ cm ⁇ 1 .
  • the solid electrolyte body is in the form of particles, and the particle size thereof may be 100 nm-5 ⁇ m.
  • a solid electrolyte body with a suitable particle size is easier to prepare and is beneficial to the capacity of the negative electrode.
  • the particle size of the composite solid electrolyte material is 100 nm-6 ⁇ m.
  • a second aspect of the embodiments of the present application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector, the negative electrode material layer including the negative electrode active material and the negative electrode active material and the negative electrode material described in the first aspect of the embodiments of the present application.
  • the negative electrode active material includes a carbon-based material and/or a silicon-based material.
  • the average working voltage of these two types of negative electrode active materials is lower than the above-mentioned coating layer materials, and the batteries made from them are within the normal working voltage range after leaving the factory, and the coating layer will not participate in the electrochemical reaction, which is beneficial to improve the battery cycle performance.
  • the mass of the composite solid electrolyte material is 3%-30% of the mass of the negative electrode active material.
  • the negative electrode material layer does not contain a conductive agent.
  • the composite solid electrolyte material has good conductivity due to the above-mentioned coating layer, so that no conductive agent needs to be added to the negative electrode sheet, which is beneficial to increase the mass ratio of the negative electrode active material therein.
  • the negative electrode material layer further contains a binder.
  • the negative electrode sheet provided in the second aspect of the embodiment of the present application contains both the negative electrode active material and the above-mentioned composite solid electrolyte material, so that the contact between various particles in the negative electrode sheet is good, the contact impedance is small, and the density of the negative electrode sheet is high. , less voids, and good electron paths and ion paths, which can improve the performance of the battery made from the negative electrode sheet.
  • a third aspect of the embodiments of the present application provides an all-solid-state lithium battery, including a positive electrode sheet, a negative electrode sheet, and a solid electrolyte layer between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet includes the second aspect of the embodiments of the present application. the negative electrode.
  • the coating layer of the composite solid-state electrolyte material is one or more of antimony-lithium alloy, bismuth-lithium alloy, and antimony-bismuth-lithium alloy. In the normal working voltage range of the all-solid-state lithium battery, the coating layer will not participate in the electrochemical reaction, which is beneficial to improve the cycle performance of the battery.
  • the all-solid-state lithium battery provided by the third aspect of the present application has a high discharge specific capacity and strong cycle stability due to the inclusion of the above-mentioned negative electrode sheet.
  • FIG. 1 is a schematic structural diagram of a composite solid-state electrolyte material provided by an embodiment of the present application
  • FIG. 2 is a schematic structural diagram of a negative electrode sheet provided by an embodiment of the application.
  • FIG. 3 is a schematic structural diagram of an all-solid-state lithium battery provided by an embodiment of the present application.
  • the embodiment of the present application provides a composite solid-state electrolyte material, which can be used in an all-solid-state lithium battery using a carbon-based material or a silicon-based material as a negative electrode active material, so as to improve the capacity of the negative electrode and the cycle stability of the battery. sex.
  • the composite solid electrolyte material 100 provided in the embodiment of the present application includes a solid electrolyte body 101 and a coating layer 102 coated on the surface of the solid electrolyte body 101 , and the coating layer 102 is made of antimony, bismuth, antimony-bismuth alloy, antimony One or more of lithium alloys, bismuth-lithium alloys, and antimony-bismuth-lithium alloys.
  • the material of the cladding layer 102 includes at least one of antimony (Sb), bismuth (Bi), antimony-bismuth alloy and lithium intercalation materials.
  • the composition of the antimony-lithium alloy can be represented by the general formula Li x Sb, 0 ⁇ x ⁇ 3; the composition of the bismuth-lithium alloy can be represented by the general formula Li y Bi, 0 ⁇ y ⁇ 3.
  • the composite solid electrolyte material 100 can be given good electronic conductivity and ionic conductivity.
  • the composite solid electrolyte material 100 is applied to the negative electrode of the battery, It is also beneficial to form good contact between the composite solid electrolyte materials 100 and the active particles of the negative electrode, obtain a negative electrode sheet with higher density and less voids, and establish a good electronic path and ion path.
  • the composite solid-state electrolyte material 100 can improve the electrochemical performance of the all-solid-state battery using the silicon-based material or carbon-based material as the negative electrode with a small amount of addition to the silicon-based or carbon-based negative electrode, without significantly reducing the negative electrode capacity and battery energy density.
  • the above-mentioned coating layer 102 is a metal material with certain ionic conductivity and good electronic conductivity, and due to the diffusion effect of metal elements in the coating layer under pressure, the composite solid electrolyte material 100 is compressed. Good contact can be achieved between them, and poor contact due to differences in crystal phases and grain boundaries can be avoided.
  • the coating layer 102 also has a certain "softness" and has a certain deformation ability, which can also improve the contact density between the composite solid electrolyte material 100 and the negative electrode active material, and reduce the voids. In the negative electrode sheet of the same volume , which can accommodate more negative electrode active materials without significantly reducing the negative electrode capacity and battery energy density.
  • the lithium intercalation potential and delithiation potential of the same material are similar.
  • Li + is extracted from the lattice of the positive electrode material, and then embedded into the negative electrode after passing through the solid electrolyte layer; during discharging, Li + is released from the negative electrode, and is embedded back into the lattice of the positive electrode material after passing through the solid electrolyte layer. middle. Therefore, during the charging process of the battery, the potential of the negative electrode side is gradually reduced, and the material with higher lithium intercalation potential first obtains Li + ; when the battery is discharged, the potential of the negative electrode side is gradually increased, and the lower the lithium extraction (intercalation) potential is. The material first desorbs Li + .
  • antimony (Sb), bismuth (Bi) to lithium potential (0.8V-0.95V) is higher than the working voltage of silicon-based negative electrode or carbon-based negative electrode (potential to metal lithium is less than 0.4V).
  • the battery using this solid-state electrolyte material in the silicon-based or carbon-based negative electrode will be better than the silicon-based or carbon-based negative electrode when it is first charged
  • the base negative electrode undergoes a lithium intercalation reaction to become the corresponding lithium intercalation material - antimony lithium alloy Li x0 Sb, bismuth lithium alloy Li y0 Bi or antimony bismuth lithium alloy Li z0 Sb m
  • the coating layer material It is antimony lithium alloy Li x Sb, bismuth lithium alloy Li y Bi, antimony bismuth lithium alloy Li z Sb m Bin , and when x >x0, y>y0, z>z0, it will come out during the first discharge process of the above-mentioned battery Part of the lithium becomes Li x0 Sb, Li y0 Bi or Li z0 Sb m Bin , and in the non-first charge and discharge process of the battery, it no longer participates in the electrochemical reaction, and mainly plays the role of conducting lithium ions and electrons.
  • the coating layer 102 uniformly coats the surface of the solid electrolyte body 101 . In some embodiments of the present application, the coating layer 102 completely coats the surface of the solid electrolyte body 101 .
  • the thickness of the cladding layer 102 is 5 nm-1 ⁇ m.
  • the thickness of 5nm-1 ⁇ m can achieve a uniform coating effect, and at the same time, the ionic conductivity of the composite solid electrolyte material will not be reduced due to an excessively thick coating thickness.
  • the thickness of the coating layer 102 may be 8 nm, 10 nm, 15 nm, 20 nm, 24 nm, 50 nm, 100 nm, 150 nm, 200 nm, 500 nm, 800 nm, 900 nm or 1 ⁇ m.
  • the thickness of the cladding layer 102 is 10 nm-200 nm.
  • the thickness is more conducive to forming a coating layer with a suitable thickness, uniform coating and complete coating, and will not increase the cost due to the coating being too thick, so that the composite solid electrolyte material can better take into account high ionic conductivity and electronic conductivity.
  • the thickness of the cladding layer 102 is 10 nm-20 nm.
  • the mass ratio of the coating layer 102 is 0.5%-30%.
  • the mass ratio can ensure that the thickness of the coating layer 102 is appropriate and the coating integrity of the solid electrolyte body 101 is high, so that a complete coating layer cannot be formed due to the low quality of the coating layer 102 , and Due to the high quality of the coating layer, the coating layer will not be too thick, the ionic conductivity of the composite solid electrolyte material 100 will be deteriorated, and the cost thereof will not be increased.
  • the mass ratio of the coating layer 102 in the composite solid electrolyte material 100 is 0.5%-10%, and in still other embodiments, the mass ratio of the coating layer 102 in the composite solid electrolyte material 100 is 0.5%-6%. In other embodiments, the mass proportion of the coating layer 102 in the composite solid electrolyte material 100 is 0.5%-2%.
  • the present application controls the ionic conductivity of the composite solid-state electrolyte material 100 at room temperature to be in the range of 1 ⁇ 10 -6 S ⁇ cm -1 to 2.5 ⁇ 10 -2 S ⁇ cm -1 through comprehensive trade-offs.
  • the present application controls the electronic conductivity of the composite solid-state electrolyte material 100 at room temperature to be in the range of 1 ⁇ 10 ⁇ 3 S ⁇ cm ⁇ 1 to 2.5 ⁇ 10 4 S ⁇ cm ⁇ 1 through comprehensive balance.
  • the solid electrolyte body 101 is in the form of particles, and its particle size (D50 particle size) may be 100 nm-5 ⁇ m.
  • the particle size can be measured by laser particle size analysis.
  • the solid electrolyte body with suitable particle size is easier to prepare, and can be better covered by the coating layer 102 , so as to improve the electrochemical performance of the composite solid electrolyte material 100 .
  • an excessively large particle size of the solid electrolyte body 101 will make the particle size of the composite solid electrolyte material 100 larger, so that the volume ratio of the negative electrode active material in the negative electrode of the battery is reduced, which is not conducive to the capacity of the negative electrode.
  • the particle size of the solid electrolyte body 101 is 100 nm-1 ⁇ m, and in still other embodiments, the particle size of the solid electrolyte body 101 is 100 nm-500 nm. In other embodiments, the particle size of the solid electrolyte body 101 is 100 nm-180 nm.
  • the particle size of the composite solid electrolyte material 100 may be 105 nm-6 ⁇ m. In some embodiments, the particle size of the composite solid electrolyte material 100 may be 110 nm-1.2 ⁇ m. In other embodiments, the particle size of the composite solid electrolyte material 100 is 110 nm-700 nm, 120 nm-520 nm.
  • the materials of the solid electrolyte body 101 include lithium fast ion conductor (LISICON) type solid electrolyte, sodium fast ion conductor (NASICON) type solid electrolyte, perovskite type solid electrolyte, garnet type solid electrolyte, sulfide At least one of solid-state electrolytes of matter type, simple lithium salts with ionic conductivity, etc., but not limited thereto.
  • the simple lithium salt with ionic conductivity can include one or more of LiF, Li 3 N, Li 3 P, and LiIn.
  • Garnet-type solid-state electrolytes and perovskite-type solid-state electrolytes belong to oxide-type solid-state electrolytes.
  • the NASICON type solid electrolyte can be one or more of LiE 2 (PO 4 ) 3 and its dopant, wherein E is Ti, Zr, Ge, Sn or Pb, and the dopant adopts the dopant
  • the hetero elements are selected from one or more of Mg, Ca, Sr, Ba, Sc, Al, Ga, In, Nb, Ta, V and the like.
  • the garnet-type solid electrolyte can be Li 7+ab-3c Al c La 3-a X a Zr 2-b Y b O 12 ; wherein 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, X is one or more of La, Ca, Sr, Ba, and K, and Y is one or more of Ta, Nb, W, and Hf.
  • the sulfide-type solid electrolyte may include one or more of crystalline sulfides, glassy sulfides, glass-ceramic sulfides, and dopants thereof.
  • the doping element in the dopant is selected from one or more of Mg, Ca, Sr, Ba, Sc, Al, Ga, In, Nb, Ta and V.
  • the glassy sulfide solid electrolyte is usually composed of at least one network former such as P 2 S 5 , SiS 2 , B 2 S 3 , and the like, and Li 2 S, a network modifier.
  • the glassy Li 2 SP 2 S 5 system may include Li 7 P 3 S 11 (ie 3.5Li 2 S-1.5P 2 S 5 ), 75Li 2 S-25P 2 S 5 , 70Li 2 S-30P 2 S 5 Products such as Li 2 S and P 2 S 5 in different weight ratios.
  • Li 7 P 3 S 11 ie 3.5Li 2 S-1.5P 2 S 5
  • 75Li 2 S-25P 2 S 5 75Li 2 S-25P 2 S 5
  • 70Li 2 S-30P 2 S 5 Products such as Li 2 S and P 2 S 5 in different weight ratios.
  • glass-ceramic state sulfide glass-ceramic state Li 2 SP 2 S 5 and the like can be exemplified.
  • the embodiments of the present application also provide a method for preparing a composite solid-state electrolyte material, including:
  • a coating layer is formed on the surface of the solid electrolyte body to obtain a composite solid electrolyte material; wherein, the composite solid electrolyte material comprises a solid electrolyte body and a coating layer coated on the surface of the solid electrolyte body, so
  • the material of the coating layer includes one or more of antimony, bismuth, antimony-bismuth alloy, antimony-lithium alloy, bismuth-lithium alloy, and antimony-bismuth-lithium alloy.
  • the coating layer is formed by mechanical fusion, coating, evaporation or sputtering, but is not limited thereto.
  • the mechanical fusion is not limited to be carried out by a ball mill, a fusion machine, or other equipment that can perform coating (for example, using Nobilta particle compounding equipment, vibration modification equipment, dry impact mixing equipment, etc.).
  • the composite solid-state electrolyte material is formed by ball milling, the process is relatively simple, the control is easy, and it is suitable for industrial mass production.
  • the manner of coating may include, but is not limited to, a combination of one or more of drop coating, brush coating, spray coating, and dipping coating.
  • the methods of evaporation and sputtering belong to physical vapor deposition, and the deposition equipment used is generally more expensive.
  • the coating layer is formed by the following method: combining at least one of antimony powder, bismuth powder, antimony-bismuth alloy powder or a mixture thereof with lithium powder and the solid electrolyte body After mixing and ball milling, the coating layer is formed on the surface of the solid electrolyte body.
  • the coating formed by ball milling is an antimony-lithium alloy (Li x Sb, 0 ⁇ x ⁇ 3); when the coating material used is bismuth powder and In the case of lithium powder, the coating layer formed by ball milling is a bismuth-lithium alloy (Li y Bi, 0 ⁇ y ⁇ 3); when the coating layer raw material used is antimony-bismuth mixture powder or antimony-bismuth alloy powder and lithium powder, ball milling is formed.
  • an embodiment of the present application also provides a negative electrode sheet 10 , comprising a negative electrode current collector 11 and a negative electrode material layer 12 disposed on the negative electrode current collector 11 , and the negative electrode material layer 12 contains a negative electrode active material 120 and the above-mentioned composite solid electrolyte
  • the material 100 does not contain a conductive agent, and the composite solid electrolyte material 100 includes a solid electrolyte body 101 and a coating layer 102 covering the surface of the solid electrolyte body 101 .
  • the negative electrode sheet can be made into an all-solid-state lithium battery. Referring to FIG. 3 , the all-solid-state lithium battery 200 includes a negative electrode sheet 10 , a positive electrode sheet 20 , and a solid electrolyte layer 30 located between the positive electrode sheet 20 and the negative electrode sheet 10 .
  • the negative electrode sheet of the all-solid-state lithium battery 200 has good cycle performance and high specific capacity, which is beneficial to improve the energy density of the all-solid-state lithium battery.
  • the mass of the composite solid electrolyte material 100 is 3-30% of the mass of the negative electrode active material 120 . In some embodiments, the mass of the composite solid electrolyte material 100 is 3%-20% of the mass of the negative electrode active material 120, for example, 5%, 8%, 10%, 15%, or 20%. In other embodiments of the present application, the mass of the composite solid electrolyte material 100 is 5%-15% of the mass of the negative electrode active material 120 . If the uncoated solid electrolyte material is directly added to the existing negative electrode active materials such as silicon element and silicon oxide, the added mass of the bare solid electrolyte material needs to reach about 40% of the negative electrode active material in order to have a good cycle. performance.
  • the thickness of the negative electrode material layer 12 is 5-50 ⁇ m.
  • the negative electrode sheet 10 still has good and stable electrochemical performance.
  • the negative electrode material layer 12 may contain a binder 121, so that the negative electrode material layer is firmly fixed on the negative electrode current collector 11, and the negative electrode material layer 12 has a certain elasticity.
  • the binder 121 used in the negative electrode material layer may be polythiophene (PT), polypyrrole (PPy), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), poly propylene (PP), polystyrene (PS), polyacrylamide (PAM), ethylene-propylene-diene copolymer, styrene-butadiene rubber, polybutadiene, fluororubber (FPM), polyvinylpyrrolidone (PVP), polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol (PVA), carboxypropyl cellulose (HPC), ethyl cellulose (EC), polyethylene oxide (PEO), carboxylate
  • PT polythiophene
  • the negative electrode active material 120 includes one or more of various carbon-based materials, silicon-based materials, etc., which are commonly used in the art, and can intercalate and desorb lithium.
  • the charge-discharge voltage of the negative electrode active material is lower than the lithium intercalation potential of Sb or Bi.
  • the silicon-based material may include one or more of elemental silicon, silicon-based alloys, silicon oxides, and silicon-carbon composite materials.
  • Carbon-based materials may include graphite (eg, natural graphite, artificial graphite), non-graphitized carbon (or "amorphous carbon"), and the like. Among them, non-graphitizable carbon can be divided into soft carbon and hard carbon according to the difficulty of graphitization.
  • Soft carbon refers to amorphous carbon that is easily graphitized at 2500°C.
  • Common soft carbon materials include coke, carbon fiber, and mesocarbon microspheres.
  • Hard carbon refers to amorphous carbon that is difficult to be graphitized at a temperature above 2500 °C. It is a pyrolytic carbon of high molecular polymers.
  • Common hard carbons include resin carbon (such as polyfurfuryl alcohol resin carbon, phenolic resin carbon, etc.), organic Polymerization of pyrolytic carbon (such as PVA, PVC, PAN, etc.) and carbon black, etc.
  • the positive electrode sheet 20 may include a positive electrode current collector 21 and a positive electrode material layer 22 disposed on the positive electrode current collector 21 .
  • the positive electrode material layer 22 may include a positive electrode active material, a conductive agent, a solid electrolyte material for a positive electrode, a binder for a positive electrode, and the like.
  • the composition of the solid electrolyte layer 30 includes a solid electrolyte material. In some embodiments, the solid electrolyte layer 30 may also contain a binder.
  • the material of the binder contained in the solid electrolyte layer 30 may be the same as or different from the binder 121 in the negative electrode material layer 12, and may be arbitrarily selected from the several binders listed above.
  • the material of the binder for the positive electrode may be the same as or different from that of the binder 121 in the negative electrode material layer 12 described above.
  • the binder for the positive electrode may be one or more including fluorine-containing resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyolefin, and the like.
  • the conductive agent in the positive electrode material layer 22 is not particularly limited, and conventional materials in the field can be used, such as one of conductive carbon black (such as acetylene black, Ketjen black), carbon nanotubes, carbon fibers, graphite, and furnace black. or more.
  • the mass percentage content of the binder for positive electrodes in the positive electrode material layer 22 is 0.1-10%, and may further be 0.2-5%. In some embodiments, the mass percentage content of the conductive agent in the positive electrode material layer 22 is 0.1-20%, and further may be 1-10%.
  • the solid electrolyte material used for the positive electrode sheet 20 and the solid electrolyte material in the solid electrolyte layer 30 can be independently selected from the sodium fast ion conductor (NASICON) solid electrolyte, garnet type solid electrolyte, perovskite type solid electrolyte and sulfur-based solid electrolyte.
  • NASHCON sodium fast ion conductor
  • the solid electrolyte layer 30 is selected from a reduction-resistant solid electrolyte material to protect the negative electrode active material on the negative electrode sheet 10 and further improve its cycle stability;
  • the solid electrolyte material for the positive electrode is selected from an electrolyte material with high ionic conductivity.
  • the particle size of the solid electrolyte material used may be 20 nm-5 ⁇ m.
  • the positive active material includes, but is not limited to, one or more of oxide type, sulfide type, polyanion type, and a composite of the above materials.
  • the particle size of the positive electrode active material is 100 nm-500 ⁇ m, for example, 100 nm-100 ⁇ m, 100 nm-50 ⁇ m, or 500 nm-50 ⁇ m.
  • the oxide-type positive active material may include TiO 2 , Cr 3 O 8 , V 2 O 5 , MnO 2 , NiO, WO 3 , LiMn 2 O 4 (lithium manganate), Li 2 CuO 2 , LiCo m Ni 1-m O 2 ( 0 ⁇ m ⁇ 1 ), LiCo a Ni 1-ab Al b O 2 , LiFe c Mn d Ge O 4 and Li 1+f L 1-g-h H g R h O At least one of 2 and so on.
  • LiCo a Ni 1-ab Al b O 2 0 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 1.
  • L, H and R are independently selected from Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu , at least one of Zn, Mo, F, I, S and B, and L, H and R are different elements from each other, and -0.1 ⁇ f ⁇ 0.2, 0 ⁇ g ⁇ 1, 0 ⁇ h ⁇ 1,0 ⁇ g+h ⁇ 1.
  • the sulfide-type positive active material may include TiS 2 , V 2 S 3 , FeS, FeS 2 , WS 2 and LiJS i (J is selected from at least one of Ti, Fe, Ni, Cu and Mo, and 1 ⁇ at least one of i ⁇ 2.5) and the like.
  • the polyanionic positive active material may specifically include at least one of LiFePO 4 (lithium iron phosphate), Li 3 V 2 (PO 4 ) 3 (lithium vanadium phosphate), and LiVPO 4 F.
  • the surface of the positive electrode active material may also be provided with a coating layer to optimize the interface between the positive electrode active material and the solid electrolyte layer 30 , reduce the interface impedance, and improve the cycle stability.
  • the coating layer on the surface of the positive electrode active material may be at least one of LiNbO 3 , LiTaO 3 , Li 3 PO 4 , Li 4 Ti 5 O 12 , and the like.
  • the negative electrode current collector 11 and the positive electrode current collector 21 are independently selected from metal foils or alloy foils.
  • the metal foil material includes copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold or silver foil material
  • the alloy foil material includes stainless steel, or copper, titanium, aluminum, platinum, Alloys of at least one element of iridium, ruthenium, nickel, tungsten, tantalum, gold and silver.
  • the negative electrode current collector 11 may specifically be a copper foil
  • the positive electrode current collector 21 may specifically be an aluminum foil. The thickness and surface roughness of the negative electrode current collector 11 and the positive electrode current collector 21 of the present application can be adjusted according to actual needs.
  • a method for preparing an all-solid-state lithium battery shown in FIG. 3 which includes the following steps:
  • preparing the positive electrode sheet 20 mixing the positive electrode active material, the solid electrolyte material for the positive electrode, the conductive agent, the binder for the positive electrode and the third solvent to obtain a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector 21, after drying and pressing, a positive electrode material layer 22 is formed on the positive electrode current collector 21 to obtain a positive electrode sheet 20;
  • the negative electrode sheet 10 with the above-mentioned solid electrolyte layer 30 is attached to the above-mentioned positive electrode sheet 20, so that the positive electrode material layer 22 is in contact with the solid electrolyte layer 30, and after pressing treatment, all solid-state lithium is obtained Battery 100.
  • first solvent, second solvent and third solvent are conventional choices in the art, for example, can be independently selected from water, ethanol, N-methylpyrrolidone (NMP), acetone, acetonitrile, toluene, xylene, benzene At least one of methyl ether, heptane, decane, ethyl acetate, ethyl propionate, butyl butyrate, and the like.
  • the dosage of each solvent can generally be 50-400wt% of the dry material mass in the corresponding mixed slurry.
  • the mass of the first solvent accounts for 50-400 wt % of the sum of the mass of the composite solid electrolyte material, the negative electrode active material, and the negative electrode binder.
  • the pressing treatment may include at least one treatment method among roll pressing, hot pressing, isostatic pressing, and the like.
  • the pressing process includes hot pressing and isostatic pressing in sequence.
  • the temperature of the hot-pressing treatment may be, but not limited to, about 100° C., and the hot-pressing treatment time is 0.5-3 hours.
  • the pressure of the isostatic pressing is above 100MPa, for example, the pressure is 100-300MP; the time of the isostatic pressing is 3-10min.
  • the above-mentioned method for preparing an all-solid-state lithium battery can prepare the above-mentioned all-solid-state lithium battery with high discharge specific capacity and strong cycle stability, and the process is simple, easy to control, and can be mass-produced.
  • the coating layer will not participate in the electrochemical reaction of intercalation/delithiation, and mainly plays the role of conducting lithium ions and electrons, and has relatively low properties. Stable, no volume change occurs, which can improve the cycle stability of the battery.
  • a method for preparing an all-solid-state lithium battery comprising the following steps:
  • the composite solid electrolyte material under a protective atmosphere, 1000g of glassy chalcogenide solid electrolyte material 70Li 2 S 30P 2 S 5 (particle size is about 1 ⁇ m), 50g of Sb powder, and 8g of lithium powder are placed in the A ball mill was used for 20 min at a speed of 150 rpm to obtain a Li 3 Sb-coated 70Li 2 S ⁇ 30P 2 S 5 composite solid electrolyte material, wherein the thickness of the coating layer was 50 nm, and the mass ratio of the coating layer was 50 nm. is 5%, and the particle size of the composite solid electrolyte material is 1 ⁇ m.
  • Si negative electrode active material 1000g of Si negative electrode active material, 150g of the above-mentioned composite solid electrolyte material, and 30g of binder SBR were added to 1000mL of toluene solvent, and then stirred in a mixer to form a stable and uniform negative electrode slurry; the negative electrode slurry
  • the material is uniformly and intermittently coated on copper foil (width 160mm, thickness 16 ⁇ m), then dried at 100°C, and pressed by a roller press to form a negative electrode material layer on the copper foil to obtain a negative electrode sheet.
  • LiCoO2 positive active material coated with LiNbO3 150g of Li10GeP2S12 solid electrolyte material, 30g of butadiene rubber binder and 20g of acetylene black, 20g of carbon fiber were added to 1500g of toluene solvent , and then stirred in a vacuum mixer to form a stable and uniform positive electrode slurry; the positive electrode slurry was uniformly and intermittently coated on aluminum foil (aluminum foil size: width 160mm, thickness 16 ⁇ m), and then dried at 100 ° C , after being pressed by a roller press, a positive electrode material layer with a thickness of 35 ⁇ m is formed on the aluminum foil to obtain a positive electrode sheet;
  • aluminum foil aluminum foil size: width 160mm, thickness 16 ⁇ m
  • a method for preparing an all-solid-state lithium battery is different from Example 1 in that: in step (1), no lithium powder but only Sb powder is added when preparing the composite solid-state electrolyte material.
  • the particle size of the composite solid electrolyte material prepared in Example 2 is 1 ⁇ m, the coating layer is an Sb layer, the thickness of the coating layer is 45 nm, and the mass ratio of the coating layer is 5%.
  • a method for preparing an all-solid-state lithium battery which differs from Example 1 in that: in step (1), when preparing the composite solid-state electrolyte material, the glassy chalcogenide solid-state electrolyte material 70Li 2 S 30P 2 S 5 is used.
  • the particle size is 6 ⁇ m, and 500g of Sb powder and 80g of lithium powder are used instead of 50g of Sb powder and 8g of lithium powder.
  • Example 3 the particle size of the composite solid electrolyte material is 8 ⁇ m, the coating layer is Li 3 Sb, the thickness of the coating layer is 2 ⁇ m, and the mass ratio of the coating layer is 37%.
  • a method for preparing an all-solid-state lithium battery which differs from Example 1 in that: in step (1), 50g of Bi powder and 5g of lithium powder are added instead of 50g of Sb when preparing the composite solid-state electrolyte material powder and 8g of lithium powder.
  • Example 4 the particle size of the composite solid electrolyte material is 1 ⁇ m, the coating layer is Li 3 Bi, the thickness of the coating layer is 40 nm, and the mass ratio of the coating layer is 5.2%.
  • a method for preparing an all-solid-state lithium battery, which is different from Example 4 is: in step (1), when preparing the composite solid-state electrolyte material, no lithium powder is added, and only 50 g of Bi is used.
  • the particle size of the composite solid electrolyte material prepared in Example 5 is 1 ⁇ m, the coating layer is a Bi layer, the thickness is 35 nm, and the mass ratio of the coating layer is 4.76%.
  • a method for preparing an all-solid-state lithium battery which differs from Example 1 in that: during the production of the negative electrode sheet, it is not necessary to process the exposed solid-state electrolyte material 70Li 2 S 30P 2 S 5 , and 150 g of exposed solid electrolyte material is directly used.
  • the solid electrolyte material 70Li 2 S ⁇ 30P 2 S 5 was used to manufacture the negative electrode sheet.
  • a method for preparing an all-solid-state lithium battery, which is different from Example 1 is: when the negative electrode sheet is made, it is not necessary to process the exposed solid-state electrolyte material 70Li 2 S 30P 2 S 5 , and 150 g of exposed solid-state electrolyte material is directly used. Electrolyte material 70Li 2 S ⁇ 30P 2 S 5 and 60 g of acetylene black conductive agent were used to prepare the negative electrode sheet.
  • a method for preparing an all-solid-state lithium battery which differs from Example 1 in that: when preparing the negative electrode sheet, carbon-coated Si is used as the negative electrode active material, and no solid electrolyte material is added.
  • the preparation method of the carbon-coated Si material is as follows: 1000 g of Si and 240 g of sucrose are placed in 1000 mL of deionized water and stirred evenly, then heated to 100° C. during the stirring process, and the solid matter is taken out after the water evaporates. , heated to 300 °C in an inert atmosphere to obtain a carbon-coated silicon anode material.
  • a method for preparing an all-solid-state lithium battery which differs from Example 1 in that: when preparing the negative electrode sheet, a bare solid electrolyte material 70Li 2 S ⁇ 30P 2 S 5 is used, and carbon-coated Si is used as the negative electrode active material. Material.
  • a method for preparing an all-solid-state lithium battery which differs from Comparative Example 4 in that: when preparing the negative electrode sheet, the amount of the solid electrolyte material 70Li 2 S ⁇ 30P 2 S5 is 400g.
  • the Si negative electrode material and the composite solid electrolyte material provided by the present application are used to make the negative electrode sheet of the all-solid-state battery, the discharge specific capacity of the negative electrode of the battery can be higher, and the cycle stability of the battery can be better.
  • the carbon-coated Si in Comparative Examples 3-4 is a traditional silicon negative electrode for all-solid-state lithium batteries, which can be regarded as a composite of Si+conducting agent.
  • the solid-state battery will not be able to perform normal charge-discharge cycles due to the lack of ion channels; but the carbon-coated silicon negative electrode material
  • the cycle performance of the obtained battery is improved compared to Comparative Example 1, but it is still far less than that of the embodiment of the present application.
  • the solid electrolyte material with a specific coating layer is introduced into the negative electrode of the all-solid lithium battery, which can make the discharge specific capacity of the negative electrode of the battery higher and the cycle stability of the battery better.

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Abstract

提供了一种用于电池负极的复合固态电解质材料、负极片及全固态锂电池，其中用于电池负极的复合固态电解质材料包括固态电解质本体和包覆在固态电解质本体表面的包覆层，包覆层的材质包括锑、铋、锑铋合金、锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。

Description

用于电池负极的复合固态电解质材料、负极片及全固态锂电池
优先权信息
本申请请求于2021年03月19日向中国国家知识产权局提交的、专利申请号为202110296962.6、申请名称为“用于电池负极的复合固态电解质材料、负极片及全固态锂电池”的中国专利申请的优先权，并且其全部内容通过引用结合在本公开中。
技术领域
本申请涉及电池技术领域，特别是涉及一种用于电池负极的复合固态电解质材料、负极片及全固态锂电池。
背景技术
近年来，使用固态电解质的全固态锂电池因具有较高的安全性而得到广泛关注。其中，理论比容量较高、安全性高的硅负极被认为是突破全固态锂电池能量密度的有效路径。但在实际的硅负极片的制备中，通常需要在硅负极中添加大量的固态电解质材料和导电剂，以提升硅负极的导离子性和导电子性，这些不具备电化学活性的添加剂的大量添加反而会降低硅负极的容量以及整个全固态锂电池的能量密度。
公开内容
鉴于此，本申请实施例提供了一种用于电池负极的复合固态电解质材料、负极片及全固态锂电池，通过在固态电解质本体的表面包覆特定的包覆层，可使得复合固态电解质材料同时具有优异的电子电导性和离子电导性，其在负极中以较少量添加就可提升负极的电化学性能，且不会明显降低负极容量及降低电池能量密度。
具体地，本申请实施例第一方面提供了一种用于电池负极的复合固态电解质材料，包括固态电解质本体和包覆在所述固态电解质本体表面的包覆层，所述包覆层的材质包括锑、铋、锑铋合金、锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。
本申请实施例第一方面提供的用于电池负极的复合固态电解质材料，通过在固态电解质本体的表面包覆上述特定包覆层，能赋予所述复合固态电解质材料良好的电子电导性及离子电导性，并利于复合固态电解质材料颗粒之间及其与负极活性颗粒之间形成良好接触，制得致密度较高、空隙较少的负极片，并在其中建立良好的电子通路和离子通路，进而可利于电池性能的提升。
此外，该复合固态电解质材料在与充放电电压平台低于其包覆层对锂电位的负极活性 材料共同制得电池负极片后，由该负极片制得的全固态锂电池的工作电压范围内，复合固态电解质材料的包覆层以锑锂合金、铋锂合金和锑铋锂合金的至少一种形式稳定存在，并不会参与嵌/脱锂的电化学反应，主要起到传导锂离子和电子的作用，性质较稳定，不发生体积变化，可提升电池的循环稳定性。
本申请实施方式中，所述包覆层的厚度为5nm-1μm。该厚度可在达到均匀包覆效果的同时，又不会降低复合固态电解质材料的离子电导性。
本申请实施方式中，所述复合固态电解质材料中，所述包覆层的质量占比为0.5％-30％。该质量占比可以保证包覆层的厚度较合适且包覆完整度较高，较好地兼顾高电子电导性和良好离子电导性。
本申请实施方式中，所述复合固态电解质材料在室温下的离子电导率在1×10 -6S·cm -1至2.5×10 -2S·cm -1的范围内。
本申请实施方式中，所述复合固态电解质材料在室温下的电子电导率在1×10 -3S·cm -1至2.5×10 4S·cm -1的范围内。
本申请实施方式中，所述固态电解质本体为颗粒状，其粒径可以为100nm-5μm。合适粒径的固态电解质本体较易制备，且利于负极容量发挥。
本申请实施方式中，所述复合固态电解质材料的粒径为100nm-6μm。
本申请实施例第二方面提供了一种负极片，包括负极集流体和设置在所述负极集流体上的负极材料层，所述负极材料层包括负极活性材料和本申请实施例第一方面所述的复合固态电解质材料。
本申请实施方式中，所述负极活性材料包括碳基材料和/或硅基材料。这两类负极活性材料的平均工作电压低于上述包覆层材料，由它们制得的电池在出厂后的正常工作电压范围内，包覆层不会参与电化学反应，利于提升电池循环性能。
本申请实施方式中，所述复合固态电解质材料的质量为所述负极活性材料质量的3％-30％。
本申请实施方式中，所述负极材料层不含导电剂。复合固态电解质材料因具有上述包覆层而具有良好导电性，使得负极片中无需加入导电剂，利于提升负极活性材料在其中的质量占比。
本申请一些实施方式中，所述负极材料层还含有粘结剂。
本申请实施例第二方面提供的负极片，同时含有负极活性材料和上述复合固态电解质材料，可使得负极片中各种颗粒之间的接触情况良好，接触阻抗小，负极片的致密度较高、空隙较少，并具有良好的电子通路和离子通路，进而可提升由该负极片制得的电池的性能。
本申请实施例第三方面提供了一种全固态锂电池，包括正极片、负极片以及位于所述 正极片和负极片之间的固态电解质层，所述负极片包括本申请实施例第二方面所述的负极片。
本申请实施方式中，当所述全固态锂电池出厂后，所述复合固态电解质材料的包覆层为锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。在该全固态锂电池的正常工作电压范围内，包覆层不会参与电化学反应，利于提升电池循环性能。
本申请第三方面提供的全固态锂电池，由于包含了上述负极片，使得该电池的放电比容量较高、循环稳定性强。
本公开的附加方面和优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本公开的实践了解到。
附图说明
此处所说明的附图用来提供对本申请的进一步理解，构成本申请的一部分，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。在附图中：
图1为本申请一实施方式提供的复合固态电解质材料的结构示意图；
图2为本申请一实施方式提供的负极片的结构示意图；
图3为本申请一实施方式提供的全固态锂电池的结构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行详细说明。
请参阅图1，本申请实施例提供了一种复合固态电解质材料，可用于碳基材料或硅基材料等作负极活性材料的全固态锂电池中，以提高负极的容量发挥及电池的循环稳定性。具体地，本申请实施例提供的复合固态电解质材料100包括固态电解质本体101和包覆在固态电解质本体101表面的包覆层102，包覆层102的材质包括锑、铋、锑铋合金、锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。换句话说，包覆层102的材质包括锑(Sb)、铋(Bi)、锑铋合金及其嵌锂材料中的至少一种。
其中，锑锂合金的组成可以以通式Li xSb表示，0<x≤3；铋锂合金的组成可以以通式Li yBi表示，0<y≤3。锑铋合金的组成可以以通式Sb mBi n表示，m+n＝1；锑铋锂合金的组成可以以通式Li zSb mBi n表示，其中，m+n＝1，0<z≤3。
通过在固态电解质本体101的表面包覆上述特定的包覆层102，能赋予复合固态电解质材料100良好的电子电导性及离子电导性，在将该复合固态电解质材料100应用到电池负极中时，还利于复合固态电解质材料100之间及其与负极活性颗粒之间形成良好接触，制得致密度较高、空隙较少的负极片，并建立良好的电子通路和离子通路。此外，该复合固 态电解质材料100在硅基或碳基负极中以较少量添加就可提升以硅基材料或碳基材料为负极的全固态电池的电化学性能，不会明显降低负极容量及电池能量密度。
具体地，上述包覆层102为具有一定离子电导性和良好电子电导性的金属材料，且由于包覆层中金属元素在受压下的扩散作用，使得复合固态电解质材料100在受压时颗粒之间能实现良好接触，可避免因晶相、晶界的不同而产生接触不良。此外，该包覆层102还具有一定的“柔软性”，具有一定变形能力，也可提高复合固态电解质材料100与负极活性材料之间的接触致密性、减少空隙，在相同体积的负极片中，可容纳较多的负极活性材料，不会明显降低负极容量及电池能量密度。
一般地，同一材料的嵌锂电位与脱锂电位相近。在全固态电池的充电过程中，Li +从正极材料的晶格中脱出，经过固态电解质层后嵌入到负极；放电时Li +从负极脱出，经过固态电解质层后嵌回到正极材料的晶格中。因此，在电池充电过程中，负极侧电位是逐渐降低的，嵌锂电位越高的材料先得到Li +；在电池放电时，负极侧电位是逐渐升高的，脱(嵌)锂电位越低的材料先脱出Li +。
而锑(Sb)、铋(Bi)的对锂电位(0.8V-0.95V)大于硅基负极或碳基负极等的工作电压(对金属锂的电位小于0.4V)。当包覆层材料为锑、锑锂合金Li xSb(0<x<3)、铋、铋锂合金Li yBi(0<y<3)，锑铋合金(Sb mBi n，m+n＝1)、锑铋锂合金Li zSb mBi n(0<z<3)时，硅基或碳基负极中使用该合固态电解质材料的电池在首次充电时，会优于硅基或碳基负极发生嵌锂反应而成为相应的嵌锂材料-锑锂合金Li x0Sb、铋锂合金Li y0Bi或锑铋锂合金Li z0Sb mBi n，(其中，x0、y0、z0为(0，3]中的固定值，且x0＞x，y0＞y，z0＞z，以x0为例，Li x0Sb的电位略高于电池负极活性材料(如Si单质)的电位)，首次放电过程中并不脱锂；之后在电池的非首次充放电过程中，包覆层材料以前述锑锂合金Li x0Sb、铋锂合金Li y0Bi或锑铋锂合金Li z0Sb mBi n的形式存在，不再参与嵌/脱锂的电化学反应，不发生体积变化，主要起到传导锂离子和电子的作用，不发生体积变化，可提升电池的循环稳定性。相应地，当包覆层材料为锑锂合金Li xSb、铋锂合金Li yBi、锑铋锂合金Li zSb mBi n，且x＞x0、y＞y0、z＞z0时，在上述电池的首次放电过程中会脱出一部分锂而成为Li x0Sb、Li y0Bi或Li z0Sb mBi n，而在电池的非首次充放电过程中，也不再参与电化学反应，主要起到传导锂离子和电子的作用。
本申请实施方式中，包覆层102在固态电解质本体101的表面均匀包覆。本申请一些实施方式中，包覆层102完全包覆固态电解质本体101的表面。
本申请实施方式中，包覆层102的厚度为5nm-1μm。5nm-1μm的厚度可实现均匀包覆效果的同时，又不会因包覆厚度过厚而降低复合固态电解质材料的离子电导性。具体地，包覆层102的厚度可以为8nm、10nm、15nm、20nm、24nm、50nm、100nm、150nm、200nm、 500nm、800nm、900nm或1μm。在一些实施例中，包覆层102的厚度为10nm-200nm。该厚度更有利于形成厚度合适、包覆均匀、完整的包覆层，且不会因包覆过厚而增加成本，使复合固态电解质材料更好地兼顾高离子电导率和电子电导率。本申请一些实施方式中，包覆层102的厚度为10nm-20nm。
本申请实施方式中，复合固态电解质材料100中，包覆层102的质量占比为0.5％-30％。该质量占比可以保证包覆层102的厚度较合适且对固态电解质本体101的包覆完整度较高，既不会因包覆层102的质量过低而不能形成完整的包覆层，又不会因包覆层质量过高而使包覆层过厚、恶化复合固态电解质材料100的离子电导性，及增加其成本等。在一些实施方式中，包覆层102在复合固态电解质材料100中的质量占比为0.5％-10％，再一些实施方式中，包覆层102在复合固态电解质材料100中的质量占比为0.5％-6％。另一些实施方式中，包覆层102在复合固态电解质材料100中的质量占比为0.5％-2％。
一般地，复合固态电解质材料100的离子电导率是越高越好，一般包覆层材料越少，复合固态电解质材料100的离子电导率越高，但包覆层可能不完整，使得复合固态电解质材料100的电子电导率较小。本申请通过综合权衡，控制复合固态电解质材料100在室温下的离子电导率在1×10 -6S·cm -1至2.5×10 -2S·cm -1的范围内。
通常，复合固态电解质材料100的电子电导率是越高越好，但这需要较多的包覆层材料，会增加复合固态电解质材料100的成本，同时会使包覆层过厚而劣化复合固态电解质材料100的离子电导性。本申请通过综合权衡，控制复合固态电解质材料100在室温下的电子电导率在1×10 -3S·cm -1至2.5×10 4S·cm -1的范围内。
需要说明的是，本申请上述的室温指25±5℃。
本申请实施方式中，固态电解质本体101为颗粒状，其粒径(D50粒径)可以为100nm-5μm。该粒径可以采用激光粒度分析法测定。该合适粒径的固态电解质本体较易制备，且能更好地被包覆层102包覆，以提高复合固态电解质材料100的电化学性能。此外，过大粒径的固态电解质本体101会使得复合固态电解质材料100的粒径也较大，使得电池负极中负极活性材料的体积占比减小，不利于负极容量发挥。在一些实施方式中，固态电解质本体101的粒径为100nm-1μm，在再一些实施方式中，固态电解质本体101的粒径为100nm-500nm。在另一些实施方式中，固态电解质本体101的粒径为100nm-180nm。
本申请实施方式中，复合固态电解质材料100的粒径可以为105nm-6μm。在一些实施例中，复合固态电解质材料100的粒径可以为110nm-1.2μm。在另一些实施例中，复合固态电解质材料100的粒径为110nm-700nm、120nm-520nm。
本申请上述实施方式中，固态电解质本体101的材质包括锂快离子导体(LISICON)型固态电解质、钠快离子导体(NASICON)型固态电解质、钙钛矿型固态电解质、石榴石型 固态电解质、硫化物型固态电解质、具有离子电导能力的简单锂盐等中的至少一种，但不限于此。其中，具有离子电导能力的简单锂盐可以列举LiF、Li 3N、Li 3P、LiIn中的一种或多种。石榴石型固态电解质、钙钛矿型固态电解质属于氧化物型固态电解质。
具体地，NASICON型固态电解质可以为LiE 2(PO 4) 3及其掺杂物中的一种或多种，其中E为Ti、Zr、Ge、Sn或Pb，所述掺杂物采用的掺杂元素选自Mg、Ca、Sr、Ba、Sc、Al、Ga、In、Nb、Ta、V等中的一种或多种。石榴石型固态电解质可以为Li 7+a-b-3cAl cLa 3-aX aZr 2-bY bO 12；其中0≤a≤1，0≤b≤1，0≤c≤1，X为La、Ca、Sr、Ba、K中的一种或多种，Y为Ta、Nb、W、Hf中的一种或多种。钙钛矿型固态电解质的化学式可以为A 1 x1B 1 y1TiO 3、A 1 x2B 2 y2Ta 2O 6、A 3 x3B 3 y3Nb 2O 6、或A hM kD nTi wO 3，其中，x1+3y1＝2，0＜x1＜2，0＜y1＜2/3；x2+3y2＝2，0＜x2＜2，0＜y2＜2/3；x3+3y3＝2，0＜x3＜2，0＜y3＜2/3；h+2k+5n+4w＝6，h、k、n、w均大于0；A为Li、Na元素中的至少一种，B为La、Ce、Pr、Y、Sc、Nd、Sm、Eu、Gd元素中的至少一种，M为Sr、Ca、Ba、Ir、Pt元素中的至少一种，D为Nb、Ta元素中的至少一种。
所述硫化物型固态电解质可以包括结晶态硫化物、玻璃态硫化物、玻璃陶瓷态硫化物及其掺杂物中的一种或多种。在一些实施例方式中，所述掺杂物中的掺杂元素选自Mg、Ca、Sr、Ba、Sc、Al、Ga、In、Nb、Ta和V中的一种或多种。
其中，结晶态硫化物的化学组成可表示为Li dQ eP fS g(Q为Si、Ge、Sn中的一种或多种，其中d+4e+5f＝2g，0≤e≤1.5)。当Q为Ge、g＝4、e+f＝1时，该结晶态硫化物即为硫代-锂快离子导体(thio-LISICON)型。玻璃态硫化物固体电解质通常由P 2S 5、SiS 2、B 2S 3等至少一种网络形成体以及网络改性体Li 2S组成。其中，玻璃态Li 2S-P 2S 5体系可以包括Li 7P 3S 11(即3.5Li 2S-1.5P 2S 5)、75Li 2S-25P 2S 5、70Li 2S-30P 2S 5等Li 2S与P 2S 5以不同重量比组成的产品。对于玻璃陶瓷态硫化物可以列举玻璃陶瓷态Li 2S-P 2S 5等。
相应地，本申请实施例还提供了一种制备复合固态电解质材料的方法，包括：
在保护气体存在下，在固态电解质本体表面形成包覆层，得到复合固态电解质材料；其中，所述复合固态电解质材料包括固态电解质本体和包覆在所述固态电解质本体表面的包覆层，所述包覆层的材质包括锑、铋、锑铋合金、锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。
本申请实施方式中，所述包覆层通过机械融合、涂覆、蒸镀或溅射的方式形成，但不限于此。其中，所述机械融合不限于是通过球磨机、融合机或其他可以进行包覆的设备(例如使用Nobilta粒子复合化设备、振实改性设备、干式冲击混料设备等)等进行。通过球磨形成所述复合固态电解质材料，工艺较简单，易控制，适合工业化批量生产。涂覆的方式可以包括但不限于滴涂、刷涂、喷涂和浸涂等中的一种或多种的组合。蒸镀和溅射的方式 属于物理气相沉积，所用沉积设备一般较昂贵。
示例性的，本申请一些实施方式中，所述包覆层通过以下方法形成：将锑粉、铋粉、锑铋合金粉中的至少一种或其与锂粉的混合物与所述固态电解质本体混合，经球磨后，在固态电解质本体表面形成所述包覆层。其中，当所用的包覆层原料为锑粉和锂粉时，球磨形成的包覆层为锑锂合金(Li xSb，0<x≤3)；当所用的包覆层原料为铋粉和锂粉时，球磨形成的包覆层为铋锂合金(Li yBi，0<y≤3)；当所用的包覆层原料为锑铋混合物粉或锑铋合金粉以及锂粉时，球磨形成的包覆层为锑铋锂合金(Li zSb mBi n，其中，m+n＝1，0<z≤3)。
参见图2，本申请实施例还提供了一种负极片10，包括负极集流体11和设置在负极集流体11上的负极材料层12，负极材料层12含有负极活性材料120和上述复合固态电解质材料100，但不含有导电剂，复合固态电解质材料100包括固态电解质本体101和包覆在固态电解质本体101表面的包覆层102。该负极片可制成全固态锂电池。参见图3，全固态锂电池200包括负极片10、正极片20以及位于正极片20和负极片10之间的固态电解质层30。
由于在负极片10的负极材料层12中引入上述复合固态电解质材料100，使得负极材料层12中可以建立优秀的电子电导通路和离子电导通路，可以避免使用导电剂，进而可使负极活性材料在负极材料层12中的质量占比较大；同时该复合固态电解质材料的存在可使负极材料层12中各种颗粒之间的接触情况良好，负极片的致密度较高、空隙较少。在以上多重作用下，使得全固态锂电池200的负极片的循环性能好、比容量高，有利于提升该全固态锂电池的能量密度。
本申请一些实施方式中，复合固态电解质材料100的质量是负极活性材料120质量的3-30％。在一些实施方式中，复合固态电解质材料100的质量是负极活性材料120质量的3％-20％，例如为5％、8％、10％、15％或20％等。本申请另一些实施方式中，复合固态电解质材料100的质量是负极活性材料120质量的5％-15％。若在现有的硅单质、硅氧化物等负极活性材料中直接添加未经包覆的固态电解质材料，则裸露的固态电解质材料的添加质量需达到负极活性材料的40％左右才能具有良好的循环性能。
本申请一些实施方式中，负极材料层12的厚度为5-50μm。在负极材料层较厚时，负极片10仍具有良好、稳定的电化学性能。
本申请一些实施方式中，负极材料层12可以含有粘结剂121，以使负极材料层牢固固定在负极集流体11上，并使负极材料层12具有一定弹性。其中，用于负极材料层中的粘结剂121可以是聚噻吩(PT)、聚吡咯(PPy)、聚四氟乙烯(PTFE)、聚偏氟乙烯(PVDF)、聚乙烯(PE)、聚丙烯(PP)、聚苯乙烯(PS)、聚丙烯酰胺(PAM)、乙烯-丙烯-二烯共聚物、苯乙烯-丁二烯橡胶、聚丁二烯、氟橡胶(FPM)、聚乙烯吡咯烷酮(PVP)、聚酯树脂、丙烯酸树脂、酚醛树脂、环氧树脂、聚乙烯醇(PVA)、羧丙基纤维素(HPC)、 乙基纤维素(EC)、聚氧化乙烯(PEO)、羧甲基纤维素钠(CMC)和丁苯橡胶(SBR)中的一种或多种。进一步地，粘结剂121在负极材料层12中的质量百分含量为0.5-5％。例如为1-5％，或2-4％。
负极活性材料120包括本领域常用的各种可嵌脱锂的碳基材料、硅基材料等中的一种或多种。在本申请的一些实施方式中，所述负极活性材料的充放电电压比Sb或Bi的嵌锂电位低。其中，硅基材料可以包括单质硅、硅基合金、硅氧化物和硅碳复合材料中的一种或多种。碳基材料可以包括石墨(如天然石墨、人造石墨)、非石墨化炭(或称“无定形碳”)等。其中，非石墨化炭根据石墨化的难易程度可分为软碳和硬碳。软碳指在2500℃温度处理下易被石墨化的无定形碳，常见的软碳材料有如焦碳、碳纤维、中间相碳微球等。硬碳指在2500℃以上的温度下难以被石墨化的无定形碳，是高分子聚合物的热解碳，常见的硬碳包括树脂碳(如聚糠醇树脂碳、酚醛树脂碳等)、有机聚合热解碳(如PVA、PVC、PAN等)和炭黑等。
本申请实施方式中，正极片20可以包括正极集流体21和设置在正极集流体21上的正极材料层22。其中，正极材料层22可以包括正极活性材料、导电剂、正极用固态电解质材料和正极用粘结剂等。固态电解质层30的成分包括固态电解质材料。在一些实施方式中，固态电解质层30还可以含有粘结剂。
其中，固态电解质层30中所含粘结剂的材质可以与负极材料层12中的粘结剂121相同或不同，可在上述所列的几种粘结剂在任意选择。类似地，正极用粘结剂可以与上述负极材料层12中的粘结剂121的材质相同或不同。例如，正极用粘结剂可以为包括含氟树脂、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、聚烯烃等的一种或多种。正极材料层22中的导电剂没有特别限制，采用本领域的常规材料即可，如导电炭黑(如乙炔黑、科琴黑)、碳纳米管、碳纤维、石墨和炉黑等中的一种或多种。在一些实施方式中，所述正极用粘结剂在正极材料层22中的质量百分比含量为0.1-10％，进一步地可以为0.2-5％。在一些实施方式中，导电剂在正极材料层22中的质量百分比含量为0.1-20％，进一步地可以为1-10％。
正极片20用固态电解质材料及固态电解质层30中的固态电解质材料可以独立地选自钠快离子导体(NASICON)固态电解质、石榴石型固态电解质、钙钛矿型固态电解质和硫系固态电解质中的一种或者多种，但不能使用上述复合固态电解质材料。例如，固态电解质层30选择耐还原的固态电解质材料，以保护负极片10上的负极活性材料，进一步提升其循环稳定性；正极用固态电解质材料选择具有较高的离子电导率的电解质材料。进一步地，在制备固态电解质层30和正极材料层22时，所用的固态电解质材料的粒径可以为20nm-5μm。
本申请实施方式中，所述正极活性材料包括但不限于氧化物型、硫化物型、聚阴离子 型以及上述各材料的复合物中的一种或多种。在本申请一些实施方式中，所述正极活性材料的颗粒粒径为100nm-500μm，例如为100nm-100μm，100nm-50μm、或500nm-50μm。
具体地，所述氧化物型正极活性材料可以包括TiO 2、Cr 3O 8、V 2O 5、MnO 2、NiO、WO 3、LiMn 2O 4(锰酸锂)、Li 2CuO 2、LiCo mNi 1-mO 2(0≤m≤1)、LiCo aNi 1-a-bAl bO 2、LiFe cMn dG eO 4和Li 1+fL 1－g－hH gR hO 2等中的至少一种。其中，所述LiCo aNi 1-a-bAl bO 2中，0≤a≤1，0≤b≤1。所述LiFe cMn dG eO 4中，G选自Al、Mg、Ga、Cr、Co、Ni、Cu、Zn和Mo中的至少一种，且0≤c≤1，0≤d≤1，0≤e≤1，c+d+e＝1。所述Li 1+fL 1－g－hH gR hO 2中，L、H和R分别独立选自Li、Co、Mn、Ni、Fe、Al、Mg、Ga、Ti、Cr、Cu、Zn、Mo、F、I、S和B中的至少一种，且L、H和R互为不同元素，且-0.1≤f≤0.2，0≤g≤1，0≤h≤1，0≤g+h≤1。所述硫化物型正极活性材料可以包括TiS 2、V 2S 3、FeS、FeS 2、WS 2和LiJS i(J选自Ti、Fe、Ni、Cu和Mo中的至少一种，且1≤i≤2.5)等中的至少一种。所述聚阴离子型正极活性材料具体可以包括LiFePO 4(磷酸铁锂)、Li 3V 2(PO 4) 3(磷酸钒锂)和LiVPO 4F中的至少一种。
此外，本申请一些实施方式中，所述正极活性材料的表面还可以带有包覆层，以优化其与固态电解质层30之间的界面，降低界面阻抗，提高循环稳定性。具体地，正极活性材料表面的包覆层可以为LiNbO 3、LiTaO 3、Li 3PO 4、Li 4Ti 5O 12等中的至少一种。
上述负极集流体11、正极集流体21独立地选自金属箔材或合金箔材。其中，所述金属箔材包括铜、钛、铝、铂、铱、钌、镍、钨、钽、金或银箔材，所述合金箔材包括不锈钢、或含铜、钛、铝、铂、铱、钌、镍、钨、钽、金和银中至少一种元素的合金。例如，负极集流体11可以具体为铜箔、正极集流体21可以具体为铝箔。本申请负极集流体11、正极集流体21的厚度及表面粗糙度可以根据实际需求进行调整。
本申请一实施方式中，还提供了一种图3所示的制备全固态锂电池的方法，包括以下步骤：
S101，制备负极片10：在保护气体存在下，将上述复合固态电解质材料与负极活性材料、负极用粘结剂和第一溶剂混合均匀，得到负极浆料；将所述负极浆料涂布在负极集流体11上，经干燥、压片后，在负极集流体11上形成负极材料层12，得到负极片10；
S102，制备固态电解质层30：在保护气体存在下，将固态电解质材料、粘结剂和第二溶剂混合均匀，得到固态电解质浆料，将所述固态电解质浆料涂布在负极片10的负极材料层12上，干燥后形成固态电解质层30；
S103，制备正极片20：将正极活性材料、正极用固态电解质材料、导电剂、正极用粘结剂和第三溶剂混合均匀，得到正极浆料；将所述正极浆料涂布在正极集流体21上，经干燥、压片后，在正极集流体21上形成正极材料层22，得到正极片20；
S104，在保护气体存在下，将带有上述固态电解质层30的负极片10与上述正极片20相 贴合，使正极材料层22与固态电解质层30接触，经压制处理后，得到全固态锂电池100。
其中，上述第一溶剂、第二溶剂和第三溶剂为本领域的常规选择，例如可以独立地选自水、乙醇、N-甲基吡咯烷酮(NMP)、丙酮、乙腈、甲苯、二甲苯、苯甲醚、庚烷、癸烷、乙酸乙酯、丙酸乙酯、丁酸丁酯等中的至少一种。各溶剂的用量一般可以为在配置对应混合浆料中干物料质量的50-400wt％。例如，第一溶剂的质量占复合固态电解质材料、负极活性材料、负极用粘结剂的质量之和的50-400wt％。
步骤S104中，所述压制处理可以包括辊压、热压、等静压等中的至少一种处理方式。在一些实施方式中，所述压制处理依次包括热压处理和等静压处理。其中，所述热压处理的温度可以为但不限于100℃左右，所述热压处理时间为0.5-3小时。所述等静压压制的压强为100MPa以上，例如压强为100-300MP；所述等静压压制处理的时间为3-10min。
上述制备全固态锂电池的方法可以制备得到上述放电比容量较高且循环稳定性强的全固态锂电池，并且工艺简单，易控制，可大规模化生产。
需要说明的是，如上所述，在全固态锂电池200首次充放电后及非首次充放电过程中，复合固态电解质材料100中的包覆层102的材质仅包括锑锂合金(Li x0Sb)、铋锂合金(Li y0Bi)、锑铋锂合金(Li z0Sb mBi n，m+n＝1)中的一种或者多种。因此，在非首次充放电过程中，在全固态锂电池200的工作电压范围内，包覆层不会参与嵌/脱锂的电化学反应，主要起到传导锂离子和电子的作用，性质较稳定，不发生体积变化，可提升电池的循环稳定性。
下面分多个实施例对本申请实施例方案进行进一步的说明。
实施例1
一种制备全固态锂电池的方法，包括以下步骤：
(1)负极片的制作
首先制备复合固态电解质材料：在保护气氛下，将1000g的玻璃态硫系固态电解质材料70Li 2S·30P 2S 5(粒径约为1μm)、50g的Sb粉、8g的锂粉共同放置入球磨机，在150rpm的转速下进行球磨20min，即可得到Li 3Sb包覆的70Li 2S·30P 2S 5复合固态电解质材料，其中，包覆层的厚度为50nm、包覆层的质量占比为5％，复合固态电解质材料的粒径为1μm。
而后，将1000g的Si负极活性材料、150g的上述复合固态电解质材料、30g的粘接剂SBR加入到1000mL的甲苯溶剂中，然后在搅拌机中搅拌，形成稳定均一的负极浆料；将该负极浆料均匀地间歇涂布在铜箔(宽度160mm，厚度16μm)上，然后在100℃下烘干，经过辊压机压片，在铜箔上形成负极材料层，得到负极片。
(2)固态电解质层的制作
在保护气氛下，将600g的70Li 2S·30P 2S 5玻璃态硫系固态电解质材料置入含30g丁二 烯橡胶粘结剂的1200g的甲苯溶液中，加热搅拌至得到均一、稳定的浆料；将该浆料连续涂布在步骤(1)得到的负极片上，然后在100℃下烘干，在负极片上形成厚度为35μm的固态电解质层。
(3)正极片的制作
将1000g的LiCoO 2、51mL乙醇铌、12g乙醇锂、1000mL去离子水和1000mL乙醇进行充分混合，在持续的搅拌下，滴加氨水调节pH至10，将溶液蒸干，将所得粉末在400℃条件下加热8h，得到表面包覆有LiNbO 3的LiCoO 2正极活性材料；
取上述1000g经LiNbO 3包覆的LiCoO 2正极活性材料、150g的Li 10GeP 2S 12固态电解质材料、30g的丁二烯橡胶粘接剂及20g的乙炔黑、20g碳纤维加入到1500g的甲苯溶剂中，然后在真空搅拌机中搅拌，形成稳定、均一的正极浆料；将该正极浆料均匀地间歇涂布在铝箔(铝箔尺寸为：宽度160mm，厚度16μm)上，然后在100℃下烘干，经过辊压机压片后，在铝箔上形成厚度为35μm的正极材料层，得到正极片；
(4)全固态锂电池的组装
在保护气氛下，将步骤(3)中的正极片与步骤(2)中带有固态电解质层的负极片对齐放置在压片机中，贴合极耳，在100℃下热压1h，使用铝塑膜抽真空密封后，在等静压机中于200MPa压制300s，得到如图3所示的全固态锂电池。
实施例2
一种制备全固态锂电池的方法，其与实施例1的区别在于：步骤(1)中，在制备复合固态电解质材料时未加入锂粉而仅加入Sb粉。
实施例2制得的复合固态电解质材料的粒径为1μm，包覆层为Sb层，包覆层的厚度为45nm、包覆层的质量占比为5％。
实施例3
一种制备全固态锂电池的方法，其与实施例1的区别在于：步骤(1)中，在制备复合固态电解质材料时，所用玻璃态硫系固态电解质材料70Li 2S·30P 2S 5的粒径为6μm，同时使用的是500g的Sb粉和80g的锂粉，而非50g的Sb粉和8g的锂粉。
实施例3中复合固态电解质材料的粒径为8μm，包覆层为Li 3Sb，包覆层厚度为2μm，包覆层的质量占比为37％。
实施例4
一种制备全固态锂电池的方法，其与实施例1的区别在于：步骤(1)中，在制备复合 固态电解质材料时加入的是50g的Bi粉和5g的锂粉，而非50g的Sb粉和8g的锂粉。
实施例4中复合固态电解质材料的粒径为1μm，包覆层为Li 3Bi，包覆层厚度为40nm、包覆层的质量占比为5.2％。
实施例5
一种制备全固态锂电池的方法，其与实施例4的区别在于：步骤(1)中，在制备复合固态电解质材料时，未加入锂粉，仅采用50g的Bi。
实施例5制得的复合固态电解质材料的粒径为1μm，包覆层为Bi层，厚度为35nm、包覆层的质量占比为4.76％。
为突出本申请实施例的有益效果，特提供以下对比例：
对比例1
一种制备全固态锂电池的方法，其与实施例1的区别在于：在负极片的制作时，不需要对裸露的固态电解质材料70Li 2S·30P 2S 5进行处理，直接使用150g裸露的固态电解质材料70Li 2S·30P 2S 5来进行负极片的制作。
对比例2
一种制备全固态锂电池的方法，其与实施例1的区别在于：负极片的制作时，不需要对裸露的固态电解质材料70Li 2S·30P 2S 5进行处理，直接使用150g裸露的固态电解质材料70Li 2S·30P 2S 5和60g的乙炔黑导电剂来进行负极片的制作。
对比例3
一种制备全固态锂电池的方法，其与实施例1的区别在于：在制备负极片时，使用碳包覆的Si作为负极活性材料，且不添加固态电解质材料。
具体地，碳包覆的Si材料的制备方法如下：将1000g的Si和240g的蔗糖共同置于1000mL去离子水中搅拌均匀，然后在搅拌的过程中加热至100℃，待水分蒸发后取出固形物，在惰性气氛下加热至300℃，得到碳包覆的硅负极材料。
在制备对比例3的负极片时，将1000g碳包覆的硅负极材料与30g的粘结剂SBR及1000mL的甲苯配制成混合浆料，涂覆到铜箔上，经干燥、压片，制得负极片。
对比例4
一种制备全固态锂电池的方法，其与实施例1的区别在于：在制备负极片时，采用裸 露的固态电解质材料70Li 2S·30P 2S 5，且使用碳包覆的Si作为负极活性材料。
在制备对比例4的负极片时，将1000g碳包覆的硅负极材料与150g的70Li 2S·30P 2S 5材料、30g的粘结剂SBR、1000mL的甲苯配制成混合浆料，涂覆到铜箔上，经干燥、压片，制得负极片。
对比例5
一种制备全固态锂电池的方法，其与对比例4的区别在于：在制备负极片时，固态电解质材料70Li 2S·30P 2S 5的用量为400g。
为对本申请实施例的技术方案带来的有益效果进行有力支持，对实施例1-5和对比例1-5中得到的各全固态锂电池进行电化学性能测试。测试方法如下：将各实施例和对比例制得的全固态锂电池样品各取20支，在LAND CT 2001C二次电池性能检测装置上，于298±1K条件下，将各电池以0.1C的倍率进行充放电循环测试：搁置10min，先恒压充电至4.25V/0.05C截止；搁置10min；恒流放电至3V，即为1次循环，记录下首圈放电容量。重复上述循环步骤，在循环过程中当电池容量低于首次放电容量的80％时，循环终止，循环终止时的循环次数即为电池的循环寿命，每组取平均值。测试结果汇总在下表1中。
表1：各组电池样品的循环性能测试结果
Figure PCTCN2022081236-appb-000001
从表1中对比例1-5与实施例1的对比可以获知，在采用Si单质作负极活性材料时，因Si单质的电子电导性极差，若在负极片中仅加入常规的裸露型固态电解质材料，会因负 极片中缺少电子通道而使得制得的固态电池(对比例1)不具备电化学性能；即使在该体系中加入大量的导电剂(对比例2)，所得电池的电化学性能仍较差。而若将Si负极材料与本申请提供的复合固态电解质材料制成全固态电池的负极片，可使得该电池的负极的放电比容量较高，电池的循环稳定性较好。
而对比例3-4中包覆有碳的Si是传统的全固态锂电池用硅负极，可将其看成Si+导电剂的复合。当负极片中仅采用碳包覆的硅负极材料而不采用固态电解质材料时(对比例3)，固态电池会因缺少离子通道而不能进行正常充放电循环；但将该碳包覆的硅负极材料与少量的常规的固态电解质材料混合制备负极片时(对比例4)，所制得的电池的循环性能相较于对比例1有所提升，但仍远远比不上本申请实施例的全固态锂电池的性能。若想由该碳包覆的硅负极材料制得的电池具有较好的循环性能，则常规的固态电解质材料的加入量较大(对比例5)，但这会大大降低电池的负极的放电比容量。
因此，本申请实施例1-5中将带特定包覆层的固态电解质材料引入到全固态锂电池的负极，可使得电池负极的放电比容量较高，电池的循环稳定性较好。
上面结合附图对本申请的实施例进行了描述，但是本申请并不局限于上述的具体实施方式，上述的具体实施方式仅仅是示意性的，而不是限制性的，本领域的普通技术人员在本申请的启示下，在不脱离本申请宗旨和权利要求所保护的范围情况下，还可做出很多形式，均属于本申请的保护之内。

Claims (10)

  1. 一种用于电池负极的复合固态电解质材料，其中，包括固态电解质本体和包覆在所述固态电解质本体表面的包覆层，所述包覆层的材质包括锑、铋、锑铋合金、锑锂合金、铋锂合金、锑铋锂合金中的一种或者多种。
  2. 如权利要求1所述的复合固态电解质材料，其中，所述包覆层的厚度为5nm-1μm。
  3. 如权利要求1或2所述的复合固态电解质材料，其中，所述复合固态电解质材料中，所述包覆层的质量占比为0.5％-30％。
  4. 如权利要求1-3中任一项所述的复合固态电解质材料，其中，所述固态电解质本体的粒径为100nm-5μm。
  5. 如权利要求1-4中任一项所述的复合固态电解质材料，其中，所述复合固态电解质材料在室温下的离子电导率在1×10 -6S·cm -1至2.5×10 -2S·cm -1的范围内。
  6. 如权利要求1-5中任一项所述的复合固态电解质材料，其中，所述复合固态电解质材料在室温下的电子电导率在1×10 -3S·cm -1至2.5×10 4S·cm -1的范围内。
  7. 一种负极片，包括负极集流体和设置在所述负极集流体上的负极材料层，所述负极材料层包括负极活性材料和如权利要求1-6中任一项所述的复合固态电解质材料，且不含导电剂。
  8. 如权利要求7所述的负极片，其中，所述复合固态电解质材料的质量为所述负极活性材料质量的3％-30％。
  9. 如权利要求7或8所述的负极片，其中，所述负极材料层还含有粘结剂。
  10. 一种全固态锂电池，其中，包括正极片、负极片和位于所述正极片与所述负极片之间的固态电解质层，其中，所述负极片包括如权利要求7-9中任一项所述的负极片。
PCT/CN2022/081236 2021-03-19 2022-03-16 用于电池负极的复合固态电解质材料、负极片及全固态锂电池 WO2022194219A1 (zh)

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