WO2024031220A1 - Matériau de lithium modifié par polymère, feuille d'électrode négative, batterie secondaire, dispositif électrique, procédé et application - Google Patents

Matériau de lithium modifié par polymère, feuille d'électrode négative, batterie secondaire, dispositif électrique, procédé et application Download PDF

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WO2024031220A1
WO2024031220A1 PCT/CN2022/110781 CN2022110781W WO2024031220A1 WO 2024031220 A1 WO2024031220 A1 WO 2024031220A1 CN 2022110781 W CN2022110781 W CN 2022110781W WO 2024031220 A1 WO2024031220 A1 WO 2024031220A1
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lithium
polymer
negative electrode
polymer layer
independently
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PCT/CN2022/110781
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English (en)
Chinese (zh)
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薛文文
刘成勇
何晓宁
胡波兵
宁子杨
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/110781 priority Critical patent/WO2024031220A1/fr
Publication of WO2024031220A1 publication Critical patent/WO2024031220A1/fr

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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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • the present application relates to the technical field of lithium metal secondary batteries, and more specifically to polymer-modified lithium materials, negative electrode plates, electrode assemblies, secondary batteries, battery modules, battery packs, electrical devices, methods and applications.
  • lithium metal secondary batteries with high energy density are becoming more and more popular, and high energy density It is an irreversible trend in the development of lithium metal secondary batteries in the future.
  • lithium metal secondary batteries currently on the market often suffer from problems such as rapid cycle life decay and lithium dendrites.
  • this application provides a polymer-modified lithium material, negative electrode plate, electrode assembly, secondary battery, battery module, battery pack, electrical device, method and application, using the polymer-modified lithium material , can form a closely fitting and dense flexible polymer layer on the surface of the lithium anode, effectively inhibiting the contact reaction between the electrolyte and lithium, reducing the consumption of lithium on the electrolyte, extending the battery life, and further, it can also effectively inhibit Dendrite short circuit problem.
  • the application provides a polymer-modified lithium material, which includes a lithium-containing metal and a polymer Poly chemically connected to the lithium in the lithium-containing metal.
  • the polymer Poly includes the structure shown in Formula I. ;
  • Rf is independently a fluorine-substituted aliphatic group
  • Each occurrence of X is independently H or an electron-withdrawing group
  • Each occurrence of A is independently O, S or NR 11 ; wherein, R 11 is H or C 1-3 alkyl;
  • n is an integer selected from ⁇ 10;
  • n is a positive integer ⁇ 10;
  • At least one cyano group in the polymer Poly forms a chemical bond with the lithium in the lithium-containing metal.
  • the polymer Poly forms a dense and uniform flexible polymer layer on the surface of the lithium-containing metal, and the flexible polymer layer can closely adhere to the surface of the lithium-containing metal.
  • the polymer layer can act as a protective layer at the negative electrode of the lithium metal battery, effectively inhibiting the contact reaction between the electrolyte and lithium, and reducing the interaction between the electrolyte and lithium. consumption, improve Coulombic efficiency and extend cycle life.
  • the polymer Poly carries a large number of cyano groups.
  • cyano groups can form a stable chemical connection (further, form a covalent connection) with the lithium in the lithium-containing metal, firmly binding the polymer layer.
  • the polymer Poly contains a large number of fluorine-substituted aliphatic groups as side groups,
  • these aliphatic side groups with a certain length can enhance the elasticity of the polymer layer and prevent the polymer layer from cracking under large-volume deformation.
  • the introduction of fluorine can effectively regulate the uniform deposition of lithium ions.
  • the EO segment (composed of m oxyethylene units) is also introduced into the side chain of the polymer Poly, which can improve the flexibility and elasticity of the polymer layer and facilitate the close fit between the protective layer, the pole piece and the separator. Reduce interface impedance.
  • the dense and uniform flexible polymer layer can also be swollen by the electrolyte, and can provide a relatively high ionic conductivity (such as 10 -3 S/cm) after swelling, thereby ensuring that lithium ions are in the polymer layer and in the The efficient transfer of lithium at the interface greatly reduces the interfacial polarization of the battery core.
  • the structural units of the polymer Poly cooperate with each other to form a technical whole that provides the aforementioned multi-dimensional comprehensive and excellent effects.
  • each occurrence of m is independently 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • each occurrence of m is independently 1, 2, 3, 4, 5, 6, 7, or 8.
  • each occurrence of m is independently 1, 2, 3, 4, 5 or 6.
  • each occurrence of m is independently 1, 2, 3, 4 or 5.
  • each occurrence of m is independently 1, 2 or 3.
  • each occurrence of m is independently 2, 3, 4, 5 or 6.
  • each occurrence of m is independently 2, 3, 4 or 5.
  • n appears each time and is independently 2 or 3.
  • m reflects the number of EO units (oxyethylene units) with the structure "CH 2 CH 2 O".
  • the larger elastic deformation can well adapt to the larger volume expansion of the negative electrode side during the charging process and prevent the protective layer from cracking; the better flexibility is conducive to the close fit of the protective layer with the lithium metal and the separator side, reducing the interface impedance.
  • m By controlling m in an appropriate range or size, it can also work synergistically with other structural units of the polymer Poly (such as Rf chain, X group) to achieve the aforementioned multi-dimensional comprehensive and excellent effects.
  • the polymer Poly is prepared by in-situ polymerization, by controlling m in an appropriate range or size, the flexibility of the polymer layer can be effectively adjusted while maintaining a high reaction rate and effective grafting density, thereby maintaining High density of polymer layer.
  • each occurrence of Rf, the fluorine substitution rate in Rf independently satisfies >50%
  • the fluorine substitution rate in Rf independently satisfies ⁇ 55%
  • the fluorine substitution rate in Rf independently satisfies ⁇ 60%
  • the fluorine substitution rate in Rf independently satisfies ⁇ 65%;
  • the fluorine substitution rate in Rf independently satisfies ⁇ 70%
  • the fluorine substitution rate in Rf independently satisfies ⁇ 80%;
  • At least 50% of the amount of Rf in the polymer Poly satisfies the fluorine substitution rate ⁇ 80%, or ⁇ 90%;
  • At least 60% of the Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 70%, or ⁇ 80%, or ⁇ 90%;
  • At least 70% of the Rf in the polymer Poly satisfies the fluorine substitution rate ⁇ 60%, or ⁇ 70%, or ⁇ 80%, or ⁇ 90%;
  • At least 80% of the amount of Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 50%, or ⁇ 60%, or ⁇ 70%, or ⁇ 80%, or ⁇ 90%.
  • each time Rf appears the number of fluorine atoms in Rf is independently an integer ⁇ 4;
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 20;
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 16;
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 15;
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 13;
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 10;
  • the number of fluorine atoms in Rf is independently 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13.
  • the mass proportion of fluorine element in the polymer Poly is selected from 10% to 50%;
  • the mass proportion of fluorine element in the polymer Poly is selected from 15% to 50%;
  • the mass proportion of fluorine element in the polymer Poly is selected from 20% to 50%.
  • the uniform deposition of lithium ions is better controlled. , inhibits the formation of lithium dendrites, improves the cycle life of lithium ions and reduces the risk of short circuit, and can alleviate the volume expansion of the lithium anode side.
  • the control of the mass proportion of fluorine element in the polymer Poly as an example, it is beneficial to improve the lithium dendrite deposition morphology and alleviate the volume expansion of the lithium anode in lithium metal batteries under a certain charging current density.
  • each occurrence of Rf contains 2 to 10 main chain carbon atoms
  • Rf contains 2 to 8 main chain carbon atoms
  • Rf contains 2 to 7 main chain carbon atoms
  • Rf contains 3, 4, 5, 6, 7 or 8 main chain carbon atoms
  • the chain length is selected from 5 to 40, preferably from 5 to 35, from 5 to 30, from 6 to 40, from 6 to 35, from 6 to 30, another preferably selected from 8 to 40, another preferably selected from 8 to 35, another preferably selected from 8 to 30, another preferably selected from 10 to 40, another preferably selected from 10 to 35, another It is preferably selected from 10 to 30; the chain length refers to the number of skeleton atoms of the longest skeleton connecting the carbonyl site and the terminal group in Rf.
  • each time Rf appears the number of carbon atoms in Rf is an integer selected from 2 to 10;
  • the number of carbon atoms in Rf is an integer selected from 2 to 8;
  • the number of carbon atoms in Rf is an integer selected from 2 to 7;
  • the number of carbon atoms in Rf is 3, 4, 5, 6, 7 or 8.
  • the length of the side group of Rf can also be adjusted by controlling the number of carbon atoms in Rf, thereby giving the polymer layer appropriate elasticity and better preventing the polymer layer from deforming under large volume deformation. rupture.
  • each occurrence of Rf also contains one or more heteroatoms selected from the group consisting of iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.
  • each time Rf appears the number of any one of the heteroatoms in Rf is 1 or more;
  • the number of any heteroatom in Rf is selected from 1 to 5;
  • the number of any heteroatom in Rf is selected from 1, 2, 3 or 4.
  • each time Rf appears the number of heteroatoms in Rf satisfies one or more of the following:
  • the number of oxygen atoms in Rf is 1, 2, 3, 4 or 5;
  • the number of nitrogen atoms in Rf is 1, 2 or 3;
  • the number of sulfur atoms in Rf is 1, 2 or 3;
  • the number of phosphorus atoms in Rf is 1 or 2;
  • the number of iodine atoms in Rf is 1, 2, 3, 4, 5 or 6;
  • the number of silicon atoms in Rf is 1 or 2;
  • the number of boron atoms in Rf is 1 or 2.
  • each occurrence of Rf contains one or more iodine groups, -NR 12 -, -O-, -S-, -S(O) 2 -, >Si ⁇ , >B
  • An atom or atomic group in the group consisting of - and >P( O)-, wherein R 12 is H or C 1-3 alkyl;
  • R 12 is H or methyl
  • R 12 is H.
  • Rf contains one or more -O-;
  • Rf contains -S(O) 2 F
  • the polymer layer can be given special properties.
  • phosphorus has a certain flame retardant effect.
  • iodine element can also play a certain role in regulating lithium ion deposition.
  • the sulfonyl fluoride group plays a certain role in improving the ionic conductivity of the polymer layer.
  • each occurrence of the fluorine-substituted aliphatic group is independently a straight chain structure or a branched chain structure.
  • Straight-chain Rf is beneficial to improving the flexibility of polymer materials.
  • the branched Rf is beneficial to improve the swelling capacity of the electrolyte membrane, thereby increasing the ionic conductivity.
  • each time Rf occurs the structure of Rf is independently represented by Formula III-1, Formula III-2 or Formula III-3:
  • each time R 31 , R 32 and R 3 appear they are each independently H or F; each time m 3 appears, they are independently an integer selected from 2 to 10; formula III-1 contains at least 4 F atom;
  • m 3 is an integer selected from 3 to 10;
  • m 3 is an integer selected from 3 to 8;
  • m 3 is 3, 4, 5, 6, 7 or 8;
  • R 41a , R 42a , R 4a , R 41b , R 42b and R 4b appear, they are each independently H or F; each time m 4a and m4 4b appear, each time they appear, they are each independently selected from 1 to 9 (1, 2, 3, 4, 5, 6, 7, 8 and 9) integers; containing at least 4 F atoms in formula III-2;
  • n 4a and m4 4b are each independently an integer selected from 2 to 9;
  • m4a and m44b are each independently an integer selected from 2 to 8;
  • m4a and m44b are each independently an integer selected from 3 to 8;
  • m4a and m44b are each independently an integer selected from 3 to 6;
  • R 51 and R 52 are each independently H or F; each time m 5 appears, they are independently an integer selected from 2 to 10; Formula III-3 contains at least 4 F atoms;
  • n 5 is an integer selected from 3 to 10;
  • n 5 is an integer selected from 3 to 8;
  • m 5 is 3, 4, 5, 6, 7 or 8.
  • each time Rf appears the structure of Rf is as shown in Formula III-1;
  • Rf every time Rf appears, the structure of Rf is as shown in Formula III-2;
  • Rf is as shown in Formula III-3.
  • the structure of formula III-1 is a linear saturated fluorinated aliphatic chain.
  • it can give the polymer layer better elasticity and prevent the polymer layer from cracking under large-volume deformation.
  • it can be made by the fluorine element. Effectively regulates the uniform deposition of lithium ions, inhibits the formation of lithium dendrites, and alleviates the volume expansion of the lithium anode side.
  • the structure of formula III-2 can be introduced with phosphorus element, and further when Z 2 is a bond (that is, does not exist), at this time, a phosphate group is formed between -(CH 2 CH 2 O) m -Rf.
  • the phosphate ester group has a flame retardant effect and is beneficial to improving the safety performance of the battery core.
  • a sulfonyl fluoride group can be introduced into the structure of formula III-3. It has a certain positive effect on improving the ionic conductivity of the polymer layer.
  • each time Formula III-1 appears, the number of H atoms therein is 0, 1, 2, 3 or 4; each time Formula III-2 appears, the number of H atoms therein is 0, 1 , 2, 3, 4, 5 or 6; each time formula III-3 appears, the number of H atoms is 0, 1, 2, 3 or 4;
  • every time formula III-1 appears, the number of H atoms therein is 0; every time formula III-2 appears, the number of H atoms therein is 0; every time formula III-3 appears, the number of H atoms therein is 0 The number is 0.
  • the number of H atoms By controlling the number of H atoms, the number of sites available for fluorine element substitution can be controlled.
  • each occurrence of Rf is independently selected from any of the following structures:
  • each occurrence of X is independently H or an electron-withdrawing group containing 1 to 6 non-hydrogen atoms.
  • R 21 and R 22 are each independently H or methyl
  • both R 21 and R 22 are methyl.
  • each occurrence of A is independently O, S, or NH;
  • each occurrence of A is independently O or NH;
  • every time A appears it is O;
  • each occurrence of A is NH.
  • the linker A can be composed of -COOH in the cyanoacrylic acid derivative monomer or its derived reactive form (such as acid chloride form, N-succinimide ester group activation form of the carboxyl group, etc.) and different reactive functional groups Reactive functional group pairs can then generate different types of chemical bonds through coupling reactions.
  • A when A is O, S or NH, it can be obtained through a coupling reaction between -COOH or its derived reactive form in the cyanoacrylic acid derivative monomer and -OH, -SH, or -NH 2 .
  • the diversification of A is the result of the flexible combination of reaction monomers.
  • Rf in Formula I is the same; X in Formula I is the same every time it appears; A in Formula I is the same every time it appears; further, Z2 in Formula I is the same every time it appears.
  • a single type of monomer can be used for the polymerization reaction.
  • n is an integer selected from 10 to 1000, preferably an integer selected from 10 to 950, further preferably an integer selected from 10 to 800, further preferably an integer selected from 15 to 800, and further Preferably it is an integer selected from 20 to 800, more preferably it is an integer selected from 40 to 800, still more preferably it is an integer selected from 50 to 800, still more preferably it is an integer selected from 100 to 800, still more preferably it is an integer selected from 10 to 800
  • the integer of 750 is preferably an integer selected from 15 to 750, further preferably an integer selected from 20 to 750, further preferably an integer selected from 40 to 750, further preferably an integer selected from 50 to 750, further preferably is an integer selected from 80 to 750, preferably an integer selected from 100 to 750, further preferably an integer selected from 10 to 600, further preferably an integer selected from 15 to 600, further preferably 20 to 600
  • the integer is preferably an integer selected from 40 to 600, further preferably an integer selected from 50 to 600, further preferably an integer selected from 100
  • the number average molecular weight of the polymer Poly is selected from 10 kDa to 200 kDa;
  • the number average molecular weight of the polymer Poly is selected from 50 kDa to 100 kDa.
  • n in formula I is numerically equal to the degree of polymerization of the polymer Poly.
  • the molecular weight of the polymer Poly can be controlled.
  • the molecular chain length of the polymer Poly can be adjusted, which not only achieves effective wrapping of lithium-containing metals, but also maintains stable chemical connections, and can also affect the density and uniformity of the polymer layer.
  • the amount of lithium in the lithium-containing metal relative to the polymer Poly is greater than the amount of catalyst, on a molar ratio
  • the lithium-containing metal includes lithium metal or lithium alloy
  • the lithium alloy contains lithium and one or more of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel and titanium.
  • the lithium-containing metal can provide a catalyst amount, it can successfully catalyze the in-situ polymerization reaction of cyanoacrylic acid derivative monomers on the surface of the lithium-containing metal.
  • the amount of lithium metal relative to the polymer Poly only requires the contact of the catalyst to catalyze the in-situ polymerization reaction of the cyanoacrylate monomer on the surface of the lithium metal.
  • the present application provides a negative electrode sheet, wherein the negative electrode sheet includes a negative electrode sheet base and a polymer layer distributed in a stack; the negative electrode sheet base includes a layer in contact with the polymer layer. a lithium-containing layer, the lithium-containing layer contains lithium, and the polymer layer is chemically connected to at least a portion of the lithium in the lithium-containing layer;
  • the polymer layer includes the polymer Poly defined in the first aspect of this application.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side of the negative electrode sheet.
  • the flexible polymer layer can closely fit on the surface of the lithium-containing layer and can protect the negative electrode of the lithium metal battery.
  • the function of the layer can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • the amount of lithium in the lithium-containing layer relative to the polymer Poly is greater than the amount of catalyst, on a molar ratio
  • the lithium-containing layer contains lithium metal or lithium alloy.
  • the lithium-containing layer consists essentially of lithium metal.
  • the lithium-containing layer is a lithium alloy.
  • the lithium alloy contains lithium and one or more of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel and titanium;
  • the lithium-containing layer consists essentially of lithium metal
  • the lithium-containing layer is a lithium alloy.
  • the polymer layer further contains electrolyte. This is helpful to provide better ionic conductivity.
  • the electrolyte contains lithium salt and electrolyte solvent.
  • the lithium salt is selected from the group consisting of lithium hexafluorophosphate, tetrafluoroboric acid, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, lithium difluoroxalate borate, lithium perchlorate, and bisethylene glycol.
  • lithium borate acids One or more lithium borate acids;
  • the electrolyte solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butyl carbonate.
  • Ester glycol dimethyl ether, tetrahydrofuran, dioxane, methyl nonafluoro-n-butyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl
  • ether octafluoropentyl-tetrafluoroethyl ether, 1,2-di(cyanoethoxy)ethane, diphenyl ether and 18-crown ether-6.
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 5 mol/L;
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 4 mol/L;
  • the concentration of the lithium salt in the electrolyte is selected from 2 mol/L to 4 mol/L;
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 3 mol/L;
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 2 mol/L.
  • the concentration of lithium salt in the electrolyte also affects the deposition morphology of lithium ions.
  • the concentration of lithium salt will change the solvation effect of Li + in the electrolyte, thereby affecting the composition of the solid electrolyte interface film (SEI film) and the deposition morphology of lithium ions.
  • SEI film solid electrolyte interface film
  • the lithium salt in the electrolyte at an appropriate concentration, it can be achieved Dense and uniform deposition of lithium ions and small volume expansion.
  • the polymer layer can also have appropriate mechanical properties, avoid excessive lithium salt concentration that is detrimental to mechanical properties, and achieve better performance during charging and discharging. Lithium ion conductivity to avoid poor lithium ion conductivity due to insufficient lithium salt concentration.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:2;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:1;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1:2;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1:1;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1.5:1;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 4:1 to 1.5:1.
  • the mass proportion of the electrolyte in the polymer layer is selected from 9.5% to 65%;
  • the mass proportion of the electrolyte in the polymer layer is selected from 10% to 60%;
  • the mass proportion of the electrolyte in the polymer layer is selected from 20% to 60%;
  • the mass proportion of the electrolyte in the polymer layer is selected from 25% to 40%;
  • the mass proportion of the electrolyte in the polymer layer is selected from 30% to 50%.
  • the mass ratio of the electrolyte in the polymer layer can be adjusted by controlling the mass ratio of the polymer Poly and the electrolyte within an appropriate range.
  • the mass proportion of electrolyte in the polymer layer will affect the elasticity and ionic conductivity of the protective layer.
  • the presence of a certain amount of lithium salt and solvent has a plasticizing effect on the polymer layer and can improve the elasticity of the polymer layer.
  • lithium salts and solvents are incorporated into the polymer layer.
  • the polymer layer On a microscopic scale, the polymer layer has a sponge-like loose porous structure, and the pores are filled with electrolyte to provide subsequent lithium ions. Provides a path for transmission.
  • the thickness of the polymer layer is selected from 5 nm to 10 ⁇ m;
  • the thickness of the polymer layer is selected from 50 nm to 8 ⁇ m;
  • the thickness of the polymer layer is selected from 50 nm to 5 ⁇ m;
  • the thickness of the polymer layer is selected from 100 nm to 5 ⁇ m.
  • the structure of the polymer layer on the surface of lithium-containing metal can be controlled at the nanometer scale, which is beneficial to the assembled battery core showing smaller interface resistance.
  • the elastic modulus of the polymer layer at 25°C is 0.1MPa ⁇ 70MPa
  • the elastic modulus of the polymer layer at 25°C is 0.5MPa ⁇ 50MPa;
  • the elastic modulus of the polymer layer at 25°C is 1 MPa to 50 MPa;
  • the elastic modulus of the polymer layer at 25°C is selected from 10 MPa to 47 MPa;
  • the elastic modulus of the polymer layer at 25°C is 10 MPa to 45 MPa;
  • the elastic modulus of the polymer layer at 25° C. is selected from 20 MPa to 45 MPa.
  • the elastic deformation range of the polymer layer at 25°C is 50% to 700%
  • the elastic deformation range of the polymer layer at 25°C is 50% to 400%;
  • the elastic deformation range of the polymer layer at 25°C is 50% to 300%;
  • the elastic deformation range of the polymer layer at 25°C is 80% to 300%;
  • the elastic deformation range of the polymer layer at 25°C is 80% to 265%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 700%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 600%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 400%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 300%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 250%;
  • the elastic deformation range of the polymer layer at 25°C is 100% to 200%;
  • the elastic deformation range of the polymer layer at 25° C. is 100% to 190%.
  • the swelling rate of the polymer layer at 25°C is selected from 10% to 60%;
  • the swelling rate of the polymer layer at 25°C is selected from 15% to 60%;
  • the swelling rate of the polymer layer at 25°C is selected from 15% to 55%;
  • the swelling rate of the polymer layer at 25°C is selected from 15% to 45%;
  • the swelling rate of the polymer layer at 25°C is selected from 20% to 45%;
  • the swelling rate of the polymer layer at 25°C is selected from 20% to 40%;
  • the swelling rate of the polymer layer at 25°C is selected from 25% to 50%.
  • the ion conductivity of the swollen polymer layer at 25°C is 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -6 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -6 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -5 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -5 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 3 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm;
  • the ionic conductivity of the swollen polymer layer at 25°C is selected from 3 ⁇ 10 -3 S/cm to 5 ⁇ 10 -4 S/cm.
  • the negative electrode sheet substrate further includes a negative electrode current collector; the negative electrode current collector is located on a side of the lithium-containing layer away from the polymer layer.
  • a second negative active material layer may or may not be provided between the negative current collector and the lithium-containing layer, and the components in the second negative active material layer and the lithium-containing layer may Same or different.
  • the present application provides an electrode assembly, which includes a positive electrode piece, an isolation film, and the negative electrode piece described in the second aspect of the application.
  • the isolation film is disposed on the negative electrode piece and the positive electrode piece. between; the polymer layer is disposed at least on the surface of the negative electrode base body close to the side of the isolation film.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side of the negative electrode sheet in the electrode assembly.
  • the flexible polymer layer can closely adhere to the surface of the lithium-containing layer and can be used in lithium metal batteries.
  • the negative electrode acts as a protective layer, which can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • this application provides a secondary battery, which includes a cell electrolyte and the electrode assembly described in the third aspect of this application, and the cell electrolyte is disposed between the polymer layer and the positive electrode piece.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side surface of the negative electrode sheet in the secondary battery.
  • the flexible polymer layer can be closely attached to the surface of the lithium-containing layer and can be used on lithium metal.
  • the negative electrode of the battery acts as a protective layer, which can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • the components of the cell electrolyte and the electrolyte in the polymer layer may be the same or different.
  • the charging current density of the secondary battery is selected from 0.3mA/cm 2 to 12mA/cm 2 ;
  • the charging current density of the secondary battery is selected from 1mA/cm 2 to 10mA/cm 2 ;
  • the charging current density of the secondary battery is selected from 1mA/cm 2 to 6mA/cm 2 ;
  • the charging current density of the secondary battery is selected from 1 mA/cm 2 to 3 mA/cm 2 .
  • the present application provides a battery module, which includes the secondary battery described in the fourth aspect of the present application.
  • the present application provides a battery pack, which includes the battery module described in the fifth aspect of the present application.
  • this application provides an electrical device, which includes one of the secondary battery described in the fourth aspect of this application, the battery module described in the fifth aspect of this application, and the battery pack described in the sixth aspect of this application, or Various.
  • the present application provides the use of monomeric compound II in preparing negative electrode sheets, wherein the structure of monomeric compound II is as shown in formula II:
  • Rf, A, Z 2 , X and m are respectively as defined in the first aspect of this application.
  • the monomer compound II contacts the lithium in the lithium-containing layer of the negative electrode base and is polymerized in situ to form a polymer layer.
  • the monomer compound II is a cyanoacrylic acid derivative compound, in which the cyano group can contact with the lithium in the outermost layer of the negative electrode plate matrix to form a chemical connection, and the carbon-carbon double bond in it can be catalyzed by lithium.
  • the polymer is reacted to prepare the polymer-modified lithium material described in the first aspect of the present application. At this time, a firmly connected, closely fitting, dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer of the negative electrode, Can play the role of protective layer mentioned above.
  • the present application provides a method for preparing a negative electrode sheet, which includes the following steps:
  • a negative electrode plate base body the outermost layer of at least one side of the negative electrode plate base body is a lithium-containing layer, and the lithium-containing layer includes lithium-containing metal; also provide a reaction mixture containing monomer compound II and electrolyte;
  • the reaction mixture is coated on the surface of the lithium-containing layer on at least one side of the negative electrode sheet substrate, and the monomer compound II is polymerized in situ to form a polymer layer;
  • Rf, A, Z 2 , X and m are respectively as defined in the first aspect of this application;
  • the electrolyte is as defined in the second aspect of this application.
  • the cyano group in the monomer compound II can contact with the lithium in the outermost layer of the negative electrode sheet matrix to form a chemical connection (covalent connection), and the carbon-carbon double bond can occur under the catalysis of lithium.
  • the in-situ polymer reaction forms the polymer Poly represented by the aforementioned formula I, thereby preparing the polymer-modified lithium material described in the first aspect of the present application.
  • a firmly connected, closely fitting, and The dense and uniform flexible polymer layer can play the role of the protective layer mentioned above.
  • the coating is not only stably bonded to the surface of the lithium-containing layer through chemical connection to avoid falling off from the surface of the lithium-containing layer during charging and discharging, but also the coating is dense and uniform, and the coating can be The thickness is controlled at the nanometer scale, and the assembled battery core can exhibit smaller interface resistance.
  • the application provides that the monomeric compound II is contacted with at least a catalytic amount of lithium. On the one hand, it provides chemical connection sites for the polymer layer, and on the other hand, it effectively catalyzes the in-situ polymerization of cyanoacrylic acid derivative monomers.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:2;
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:1;
  • the mass ratio of the monomer compound II and the electrolyte is selected from 5:1 to 1:1;
  • the mass ratio of the monomer compound II to the electrolyte is selected from 5:1 to 1.5:1;
  • the mass ratio of the monomer compound II to the electrolyte is selected from 4:1 to 1.5:1.
  • the mass ratio of the monomer compound II and the electrolyte By controlling the mass ratio of the monomer compound II and the electrolyte, the mass ratio of the polymer Poly and the electrolyte in the generated polymer layer can be controlled.
  • the coating method is selected from the group consisting of coating, spraying, and spin coating. and any of the vapor deposition methods.
  • the reaction temperature of the in-situ polymerization is selected from 30°C to 100°C;
  • the reaction temperature of the in-situ polymerization is selected from 30°C to 50°C;
  • the reaction temperature of the in-situ polymerization is selected from 40°C to 60°C.
  • reaction time of the in-situ polymerization is selected from 0.1h to 24h;
  • reaction time of the in-situ polymerization is selected from 0.1h to 12h;
  • the reaction time of the in-situ polymerization is selected from 0.1h to 6h.
  • the coating thickness of the reaction mixture is selected from 100 nm to 8 ⁇ m;
  • the coating thickness of the reaction mixture is selected from 50 nm to 5 ⁇ m;
  • the coating thickness of the reaction mixture is selected from 50 nm to 8 ⁇ m.
  • the polymer layer formed is as defined in the second aspect of the application.
  • the negative electrode sheet base is a pure lithium sheet.
  • the battery negative electrode piece can also introduce an additional negative electrode current collector to facilitate the assembly of the tab, or a pure lithium piece covered with a polymer layer can be used as the negative electrode piece.
  • the negative electrode sheet substrate further includes a negative electrode current collector; the negative electrode current collector is located on a side of the lithium-containing layer away from the polymer layer.
  • a second negative active material layer may or may not be provided between the negative current collector and the lithium-containing layer, and the components in the second negative active material layer and the lithium-containing layer may Same or different.
  • Figure 1 is a schematic structural diagram of a negative electrode piece according to an embodiment of the present application.
  • a polymer layer is provided on one side of the negative electrode piece;
  • Figure 2 is a schematic structural diagram of a negative electrode piece according to an embodiment of the present application.
  • a polymer layer and a negative electrode current collector are provided on one side of the negative electrode piece;
  • Figure 3 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present application. There is also a second negative electrode active material layer between the lithium-containing layer and the negative electrode current collector;
  • Figure 4 is a schematic structural diagram of a negative electrode piece according to an embodiment of the present application. Polymer layers are provided on both sides of the negative electrode piece;
  • Figure 5 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present application. Polymer layers are provided on both sides of the negative electrode sheet, and a second negative electrode active material is provided between the lithium-containing layers on both sides and the negative electrode current collector. layer;
  • Figure 6 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • Figure 7 is an exploded view of the secondary battery according to one embodiment of the present application shown in Figure 6;
  • Figure 8 is a schematic diagram of a battery module according to an embodiment of the present application.
  • Figure 9 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG 10 is an exploded view of the battery pack according to an embodiment of the present application shown in Figure 9;
  • FIG. 11 is a schematic diagram of an electrical device using a secondary battery as a power source according to an embodiment of the present application.
  • Ranges disclosed herein are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive of the endpoints, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, understand that ranges of 60-110 and 80-120 are also expected. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range “0-5" means that all real numbers between "0-5" have been listed in this article, and "0-5" is just an abbreviation of these numerical combinations.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • step (c) means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c). , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b), etc.
  • condition "A or B” is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; Or both A and B are true (or exist).
  • references to “multiple”, “multiple”, “multiple”, etc. in this application refer to the number being greater than 2 or equal to 2 unless otherwise specified. For example, “one or more” means one or more than two.
  • first”, “second”, “third” and “fourth” etc. are for descriptive purposes only and shall not be understood as indicating or implying relative importance or quantity, nor shall they be understood as implicitly indicating the importance or quantity of indicated technical features.
  • first”, “second”, “third”, “fourth”, etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation of quantity.
  • Lithium metal anodes with high specific capacity (3860mAh/g) and extremely low potential (-3.04V vs.H 2 /H + ) have therefore attracted widespread attention in the industry.
  • the high reactivity and dendrite short circuit problems of lithium metal have greatly limited its further development.
  • Lithium metal has high reactivity and is prone to side reactions with the electrolyte, consuming the electrolyte and lithium metal and producing a thick passivation layer, causing the battery cycle life to rapidly decay.
  • lithium ions are deposited unevenly due to regional differences in ion flow and electron flow, resulting in dendrites.
  • lithium dendrites have a high specific surface area, which will increase the consumption of electrolyte and even cause battery diving; on the other hand, the rapid growth of lithium dendrites will penetrate the separator and bring the risk of battery short circuit.
  • a highly elastic lithium metal protective layer that has lithium ion transport and regulation functions and is tightly combined with lithium metal may solve the above problems.
  • the existence of the protective layer can reduce the direct contact between the electrolyte and lithium metal, inhibit the occurrence of side reactions, and reduce the consumption of electrolyte and lithium metal.
  • the high ionic conductivity and functional group design of the protective layer can not only ensure the effective transfer of lithium ions inside the protective layer and at the interface with lithium metal, but also regulate the uniform deposition of lithium ions and inhibit the formation of lithium dendrites. , Reduce the consumption of electrolyte and avoid dendrites from piercing the diaphragm and causing short circuit.
  • the tight combination between the protective layer and the lithium metal can prevent the coating from peeling off the surface of the lithium metal due to volume changes on the negative electrode side during charging and discharging.
  • the protective layer is attached to the surface of lithium metal through physical coating.
  • the protective layer and lithium metal are combined through intermolecular van der Waals forces, and the force is weak. Due to the volume change of the negative electrode side during long cycles, it is easy to break away from the lithium metal; the functional groups contained in the protective layer have no regulating effect on lithium deposition.
  • the protective layer is obtained independently in advance and then attached between the lithium metal and the separator, the operation is complicated and the flatness of the thin layer is difficult to ensure; in order to ensure better wettability of the lithium metal surface, high viscosity is used The polymer solution is coated on the surface of lithium metal, but the protective layer is thicker.
  • the present application includes a lithium-containing metal and a polymer Poly chemically connected to the lithium surface of the lithium-containing metal.
  • the polymer Poly has a cyanoacrylic acid derivative monomer.
  • the repeating unit structure formed simultaneously carries a large number of cyano groups and fluorine-substituted aliphatic groups Rf, and also has an oxyethylene segment (EO segment) between the main chain and the Rf side chain, and at least 10% of the polymer Poly One cyano group forms a chemical bond (further, a covalent bond) with the lithium in the lithium-containing metal.
  • a polymer-modified lithium material which includes a lithium-containing metal and a polymer Poly chemically connected to the lithium surface in the lithium-containing metal, the polymer Poly comprising Formula I structure;
  • Rf is independently a fluorine-substituted aliphatic group
  • Each occurrence of X is independently H or an electron-withdrawing group
  • Each occurrence of A is independently O, S or NR 11 ; wherein, R 11 is H or C 1-3 alkyl;
  • n is an integer selected from ⁇ 10;
  • n is a positive integer ⁇ 10;
  • At least one cyano group in the polymer Poly forms a chemical connection (further, forms a covalent connection) with the lithium in the lithium-containing metal.
  • the carbon atom to which the Rf side group is connected is also connected to a cyano group.
  • the carbon atoms connected to the cyano group can form a relatively large Stable anionic active center, and then continue the chain growth until the chain terminates.
  • lithium-containing metal may be essentially composed of lithium (Li) metal, may also be a lithium alloy, or may be a composition containing lithium metal and a lithium alloy.
  • substantially composed of lithium metal means that the weight proportion of metallic lithium is very high, and the proportion described by “substantially” here is, for example, greater than 80%, greater than 85%, greater than 90%, greater than 95%, greater than 96% , greater than 97%, greater than 98%, greater than 99%, 100%, etc.
  • lithium metal or “lithium metal” refers to lithium in the metallic state.
  • lithium used independently refers to lithium in the metallic state unless otherwise specified.
  • lithium in lithium-containing metals.
  • lithium alloy refers to an alloy containing lithium.
  • lithium alloys may also contain one or more other types of metals.
  • Lithium alloys that have been reported to be used as negative electrode active materials in lithium metal batteries all fall within the scope of this application.
  • the lithium alloy may be an alloy of lithium and one or more metals selected from the group consisting of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel, and titanium.
  • Non-limiting examples of lithium alloys include lithium magnesium alloy and lithium aluminum alloy.
  • the "chemical connection" between the cyano group and lithium refers to a covalent connection unless otherwise specified.
  • cyanoacrylic acid derivative monomer refers to a
  • the end marked with an asterisk “*” can be connected to the aforementioned oxyethylene segment (EO segment) through a linking group such as an ester group or an amide group.
  • an oxyethylene segment also called an EO segment, refers to a segment having one or more EO units (units of the structure -CH2CH2O- ).
  • aliphatic group refers to a group containing at least one carbon atom and no aromatic group, and when the aliphatic group contains only one carbon atom, the carbon atoms are connected through four single bonds Four adjacent atoms (i.e. excluding substituted methylene groups such as carbonyl groups).
  • the aliphatic group is allowed to contain one or more heteroatoms. Examples of heteroatoms include but are not limited to fluorine, iodine, nitrogen, oxygen, sulfur, silicon, boron and phosphorus.
  • the aliphatic group may be an aliphatic hydrocarbon group, one or more hydrogen atoms in the aliphatic hydrocarbon group may be independently substituted by non-fluorine heteroatoms, and one or more carbon atoms in the aliphatic hydrocarbon group may be independently substituted by Aliphatic hydrocarbon groups substituted by heteroatoms. Allow hydrogen atoms to be replaced and carbon atoms to be replaced at the same time.
  • hydrocarbyl refers to a monovalent group composed of two elements: carbon and hydrogen.
  • the hydrocarbon group can be in the form of alkyl, alkenyl, alkynyl, etc.
  • alkyl refers to a monovalent residue resulting from the loss of one hydrogen atom from a saturated hydrocarbon containing a primary carbon atom, a secondary carbon atom, a tertiary carbon atom, a quaternary carbon atom, or a combination thereof.
  • C 1 to 10 alkyl refer to alkyl groups containing 1 to 10 carbon atoms, and each occurrence may be independently C 1 alkyl, C 2 alkyl, C 3 alkyl, C 4 alkyl, C 5 alkyl, C 6 alkyl, C 7 alkyl, C 8 alkyl, C 9 alkyl or C 10 alkyl.
  • alkyl groups include, but are not limited to: methyl (Me, -CH 3 ), ethyl (Et, -CH 2 CH 3 ), 1-propyl (n-Pr, n-propyl, -CH 2 CH 2 CH 3 ), 2-propyl (i-Pr, i-propyl, -CH(CH 3 ) 2 ), 1-butyl (n-Bu, n-butyl, -CH 2 CH 2 CH 2 CH 3 ), 2-methyl-1-propyl (i-Bu, i-butyl, -CH 2 CH (CH 3 ) 2 ), 2-butyl (s-Bu, s-butyl, -CH (CH 3 )CH 2 CH 3 ), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH 3 ) 3 ), 1-pentyl (n-pentyl, -CH 2 CH 2 CH 2 CH 3 ), 2-pentyl (-CH(CH 3 )
  • alkenyl refers to a monovalent residue resulting from the loss of one hydrogen atom from a hydrocarbon containing at least one unsaturated site (i.e., a carbon-carbon sp 2 double bond).
  • C 2 to C 10 alkenyl or “C 2 to 9 alkenyl” refer to alkenyl groups containing 2 to 9 carbon atoms, each occurrence of which may independently be C 2 alkenyl, C 3 alkenyl, C 4 alkenyl , C 5 alkenyl, C 6 alkenyl, C 7 alkenyl, C 8 alkenyl, C 9 alkenyl or C 10 alkenyl.
  • alkynyl refers to a monovalent residue resulting from the loss of one hydrogen atom from a hydrocarbon containing at least one unsaturated site, that is, a carbon-carbon sp triple bond.
  • C 2 to C 10 alkynyl refer to alkynyl groups containing 2 to 9 carbon atoms, and each occurrence can be independently C 2 alkynyl, C 3 alkynyl, C 4 alkynyl, C 5 alkynyl, C 6 alkynyl, C 7 alkynyl, C 8 alkynyl, C 9 alkynyl or C 10 alkynyl.
  • Suitable examples include, but are not limited to: ethynyl (-C ⁇ CH) and propargyl (-CH 2 C ⁇ CH).
  • C 1-3 alkylene refers to an alkylene group containing 1, 2 or 3 carbon atoms. Suitable examples include methylene (-CH 2 -), ethylene (-CH 2 CH 2 - or -CH(CH 3 )-), propylene (-CH 2 CH 2 CH 2 -, -CH 2 CH(CH 3 )- or -C(CH 3 ) 2 -).
  • each occurrence of LC independently, is ethylene or propylene.
  • each occurrence of LC is independently 1,2-ethylene or 1,3-propylene.
  • each occurrence of LC independently, is 1,2-ethylene.
  • each occurrence of LC independently, is 1,3-propylene.
  • L C in formula (I) are all the same.
  • the term "coupling linker” refers to a covalent linker that can be formed by a coupling reaction between two reactive groups.
  • Z 2 does not exist (that is, when it is a bond)
  • a coupling-type linking group is formed between -(CH 2 CH 2 O) m - and Rf in formula (I);
  • Z 2 exists (at this time , Z 2 is a linking group containing at least one atom), -(CH 2 CH 2 O) m - in formula I and Z 2 constitute a coupling type linking group.
  • activated carbonate such as succinimide It is generated by the condensation reaction between amine carbonate
  • Z0 in Formula (I) are all the same.
  • the number of Rf connected to Z 0 can be 1 or 2.
  • the end group related to the polymer Poly refers to the end group formed by the polymerization reaction of carbon-carbon double bonds. Its type depends on the initiator used, the end-capping group in the termination reaction, etc. Factors are related.
  • “*" is used to describe the end group of the polymer Poly, it can be understood in conjunction with the description of the polymer reaction in this application. Those skilled in the art can correctly understand the structure of the polymer Poly.
  • Rf is fluorine-substituted hydrocarbyl.
  • Rf is fluoro-substituted alkyl.
  • Rf is fluoro-substituted alkenyl.
  • Rf is fluoro-substituted alkynyl.
  • the polymer Poly forms a dense and uniform flexible polymer layer on the surface of the lithium-containing metal.
  • This flexible polymer layer can closely fit on the surface of the lithium-containing metal and can be used at the negative electrode of the lithium metal battery. It plays the role of a protective layer, which can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • the polymer Poly carries a large number of cyano groups. One or more of these cyano groups can form a stable chemical connection (covalent connection) with the lithium in the lithium-containing metal, firmly binding the polymer layer to the lithium-containing metal.
  • the volume of the negative electrode side changes during charging and discharging, it can prevent the polymer layer from peeling off from the surface of the lithium-containing metal;
  • the polymer Poly contains a large number of fluorine-substituted aliphatic groups as side groups.
  • these Aliphatic side groups with a certain length can enhance the elasticity of the polymer layer and prevent the polymer layer from breaking under large-volume deformation.
  • the introduction of fluorine can effectively regulate the uniform deposition of lithium ions and improve certain charging.
  • the deposition morphology of lithium dendrites in lithium metal batteries under current density inhibits the formation of lithium dendrites and alleviates the volume expansion of the lithium anode side.
  • the EO segment (composed of m oxyethylene units) is also introduced into the side chain of the polymer Poly, which can improve the flexibility and elasticity of the polymer layer and facilitate the close fit between the protective layer, the pole piece and the separator. Reduce interface impedance.
  • the dense and uniform flexible polymer layer can also be swollen by the electrolyte, and can provide a relatively high ionic conductivity (such as 10 -3 S/cm) after swelling, thereby ensuring that lithium ions are in the polymer layer and in the The efficient transfer of lithium at the interface greatly reduces the interfacial polarization of the battery core.
  • the structural units of the polymer Poly cooperate with each other to form a technical whole that provides the aforementioned multi-dimensional comprehensive and excellent effects.
  • each occurrence of m is independently an integer selected from 2 to 6.
  • each occurrence of m is independently an integer selected from 2 to 5.
  • each occurrence of m is independently an integer selected from 2 to 4.
  • each occurrence of m is independently an integer selected from 2 to 3.
  • each occurrence of m is independently 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • each occurrence of m is independently 1, 2, 3, 4, 5, 6, 7, or 8.
  • each occurrence of m is independently 1, 2, 3, 4, 5, or 6.
  • each occurrence of m is independently 1, 2, 3, 4, or 5.
  • each occurrence of m is independently 1, 2, or 3.
  • each occurrence of m is independently 2, 3, 4, 5, or 6.
  • each occurrence of m is independently 2, 3, 4, or 5.
  • each occurrence of m is independently 2 or 3.
  • m reflects the number of EO units (oxyethylene units) with the structure "CH 2 CH 2 O".
  • the larger elastic deformation can well adapt to the larger volume expansion of the negative electrode side during the charging process and prevent the protective layer from cracking; the better flexibility is conducive to the close fit of the protective layer with the lithium metal and the separator side, reducing the interface impedance.
  • m By controlling m in an appropriate range or size, it can also work synergistically with other structural units of the polymer Poly (such as Rf chain, X group) to achieve the aforementioned multi-dimensional comprehensive and excellent effects.
  • the polymer Poly is prepared by in-situ polymerization, by controlling m in an appropriate range or size, the flexibility of the polymer layer can be effectively adjusted while maintaining a high reaction rate and effective grafting density, thereby maintaining High density of polymer layer.
  • the fluorine substitution rate in Rf independently satisfies >50%.
  • the fluorine substitution rate in Rf independently satisfies ⁇ 55%.
  • the fluorine substitution rate in Rf independently satisfies ⁇ 60%.
  • the fluorine substitution rate in Rf independently satisfies ⁇ 65%.
  • the fluorine substitution rate in Rf independently satisfies ⁇ 70%.
  • the fluorine substitution rate in Rf independently satisfies ⁇ 80%.
  • At least 50% of the amount of Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 80%, or ⁇ 90%.
  • At least 60% of the amount of Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 70%, or ⁇ 80%, or ⁇ 90%.
  • At least 70% of the amount of Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 60%, or ⁇ 70%, or ⁇ 80%, or ⁇ 90%.
  • At least 80% of the amount of Rf in the polymer Poly satisfies a fluorine substitution rate of ⁇ 50%, or ⁇ 60%, or ⁇ 70%, or ⁇ 80%, or ⁇ 90%.
  • the upper limit is 100%, that is, ⁇ 50% and ⁇ 60% are respectively the same as 50% to 100%. % and 60% to 100% have the same meaning.
  • the "fluorine substitution rate in Rf” is the molar proportion of fluorine atoms, based on the number of hydrogen atoms that can be substituted in the Rf group.
  • the "number of hydrogen atoms that can be substituted” can be understood as the number of sites that can be substituted in the Rf group, that is, the number of sites that can be substituted with carbon atoms, possible heteroatoms (such as phosphorus atoms, nitrogen atoms) , sulfur atoms, etc.), the hydrogen atoms can also be replaced by other elements (in this case, the sites occupied by other elements are also included in the base number).
  • the fluorine substitution rate in Rf can also be selected from the following range of any one percentage or any two percentages: 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% , 75%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 100%.
  • Non-limiting examples of intervals composed of any two percentages include 30% to 100%, 35% to 100%, etc.
  • each occurrence of Rf, the number of fluorine atoms in Rf is independently an integer ⁇ 4.
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 20.
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 16.
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 15.
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 13.
  • the number of fluorine atoms in Rf is independently an integer selected from 4 to 10.
  • the number of fluorine atoms in Rf is independently 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13.
  • the number of fluorine atoms in Rf can also be selected from any one of the following values or an interval composed of any two values: 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc.
  • Non-limiting examples of intervals composed of any two numerical values include 4 to 20, 4 to 16, etc.
  • the mass proportion of fluorine element in the polymer Poly is selected from 10% to 50%.
  • the mass proportion of fluorine element in the polymer Poly is selected from 15% to 50%.
  • the mass proportion of fluorine element in the polymer Poly is selected from 20% to 50%.
  • the mass proportion of fluorine element in the polymer Poly can also be selected from any one of the following percentages or an interval composed of any two percentages: 10%, 15%, 20%, 25%, 30%, 35%, 40 %, 45%, 50%.
  • Non-limiting examples of the interval formed by any two percentages are 30% to 50%, etc.
  • the uniformity of lithium ions can be better controlled. deposition, inhibits the formation of lithium dendrites, improves the cycle life of lithium ions and reduces the risk of short circuit, and can alleviate the volume expansion of the lithium anode side.
  • the control of the mass proportion of fluorine element in the polymer Poly as an example, it is beneficial to improve the lithium dendrite deposition morphology and alleviate the volume expansion of the lithium anode in lithium metal batteries under a certain charging current density.
  • each occurrence of Rf contains 2 to 10 backbone carbon atoms.
  • Rf contains 2-8 backbone carbon atoms.
  • Rf contains 2-7 backbone carbon atoms.
  • Rf contains 3, 4, 5, 6, 7, or 8 backbone carbon atoms.
  • each time Rf appears the number of carbon atoms in Rf is an integer selected from 2 to 10.
  • the number of carbon atoms in Rf is an integer selected from 2 to 8.
  • the number of carbon atoms in Rf is an integer selected from 2 to 7.
  • the number of carbon atoms in Rf is 3, 4, 5, 6, 7, or 8.
  • Rf is a fluorine-substituted C 2-10 aliphatic group, and the number of carbon atoms can be selected from any one of the following values or an interval consisting of any two values, such as 2 , 3, 4, 5, 6, 7, 8, 9 and 10.
  • Rf is fluorine-substituted C 2-10 hydrocarbyl.
  • the C 2-10 hydrocarbon group may be, but is not limited to, C 2-10 alkyl group, C 2-10 alkenyl group, C 2-10 alkynyl group, etc.
  • Rf is fluorine-substituted C 2-10 alkyl.
  • the number of carbon atoms can be selected from any one of the following values or an interval composed of any two values, such as 2, 3, 4, 5, 6, 7, 8, 9 and 10.
  • the C 2-10 alkyl group may be, but is not limited to, for example, ethylpropyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, tert-butyl base, isopentyl, tert-pentyl, neopentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 2- Methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 2,2-dimethylhexyl , 3,3-d
  • Rf is fluorine-substituted C 2-10 alkenyl.
  • the number of carbon atoms can be selected from any one of the following values or an interval composed of any two values, such as 2, 3, 4, 5, 6, 7, 8, 9 and 10.
  • the C 2-10 alkenyl group may be, but is not limited to, for example, vinyl, propenyl, butenyl, butadienyl, pentenyl, pentadienyl, hexenyl, etc.
  • Rf is fluoro-substituted C 2-10 alkynyl.
  • the number of carbon atoms can be selected from any one of the following values or an interval composed of any two values, such as 2, 3, 4, 5, 6, 7, 8, 9 and 10.
  • the C 2-10 alkynyl group may be, but is not limited to, for example, ethynyl, propynyl, butynyl, butadiynyl, pentynyl, pentadiynyl, hexynyl, etc. .
  • the length of the side group of Rf can also be adjusted by controlling the number of carbon atoms in Rf, thereby giving the polymer layer appropriate elasticity and better preventing the polymer layer from deforming under large volume deformation. rupture.
  • each occurrence of Rf also contains one or more heteroatoms selected from the group consisting of iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus.
  • each time Rf appears the number of any one of the heteroatoms in Rf is 1 or more.
  • the number of any one of the heteroatoms in Rf is selected from 1 to 5.
  • the number of heteroatoms of any one of Rf is selected from 1, 2, 3, or 4.
  • each time Rf appears the number of heteroatoms in Rf satisfies one or more of the following:
  • the number of oxygen atoms in Rf is 1, 2, 3, 4 or 5;
  • the number of nitrogen atoms in Rf is 1, 2 or 3;
  • the number of sulfur atoms in Rf is 1, 2 or 3;
  • the number of phosphorus atoms in Rf is 1 or 2;
  • the number of iodine atoms in Rf is 1, 2, 3, 4, 5 or 6;
  • the number of silicon atoms in Rf is 1 or 2;
  • the number of boron atoms in Rf is 1 or 2.
  • the number of oxygen atoms in Rf is 1, 2, 3, 4 or 5.
  • the number of nitrogen atoms in Rf is 1, 2 or 3.
  • the number of sulfur atoms in Rf is 1, 2 or 3.
  • the number of phosphorus atoms in Rf is 1 or 2.
  • the number of iodine atoms in Rf is 1, 2, 3, 4, 5 or 6.
  • the number of silicon atoms in Rf is 1 or 2.
  • the number of boron atoms in Rf is 1 or 2.
  • each occurrence of Rf contains one or more iodine groups, -NR 12 -, -O-, -S-, -S(O) 2 -, >Si ⁇ , >B
  • An atom or atomic group in the group consisting of - and >P( O)-, wherein R 12 is H or C 1-3 alkyl.
  • R 12 is H or methyl.
  • R 12 is H.
  • Rf contains one or more -O-.
  • Rf contains -S(O) 2F .
  • radical refers to a group of two or more atoms.
  • the polymer layer can be given special properties.
  • phosphorus has a certain flame retardant effect.
  • iodine element can also play a certain role in regulating lithium ion deposition.
  • the sulfonyl fluoride group has a certain positive effect on improving the ionic conductivity of the polymer layer.
  • each occurrence of the fluorine-substituted aliphatic group is independently a straight chain structure or a branched chain structure.
  • fluorine-substituted hydrocarbyl such as fluorine-substituted C 2-10 alkyl
  • fluorine-substituted alkyl such as fluorine-substituted C 2-10 alkyl
  • fluorine-substituted alkenyl such as fluorine-substituted C 2-10 Alkenyl
  • fluorine-substituted alkynyl such as fluorine-substituted C 2-10 alkynyl
  • Straight-chain Rf is beneficial to improving the flexibility of polymer materials.
  • the branched Rf is beneficial to improve the swelling capacity of the electrolyte membrane, thereby increasing the ionic conductivity.
  • each occurrence of the fluorine-substituted aliphatic group is independently a saturated or unsaturated structure.
  • the fluorine-substituted aliphatic group contains one or more unsaturated bonds selected from the group consisting of carbon-carbon double bonds and carbon-carbon triple bonds.
  • Rf is fluorine-substituted C 2-10 alkenyl. See the preceding definition.
  • Rf is fluoro-substituted C 2-10 alkynyl. See the preceding definition.
  • the fluorine-substituted aliphatic group When the fluorine-substituted aliphatic group has a saturated structure, it can give the molecular chain of the polymer Poly better flexibility, which is beneficial to improving the elasticity control of the polymer layer; in addition, introducing a certain unsaturated bond into Rf can moderately improve The degree of cross-linking of the polymer protective layer is beneficial to improving the elastic modulus of the material.
  • each time Rf occurs the structure of Rf is independently represented by Formula III-1, Formula III-2 or Formula III-3:
  • each time R 31 , R 32 and R 3 appear they are each independently H or F; each time m 3 appears, they are independently an integer selected from 2 to 10; formula III-1 contains at least 4 F atom;
  • m 3 is an integer selected from 3 to 10 (such as 3, 4, 5, 6, 7, 8, 9 or 10);
  • m 3 is an integer selected from 3 to 8;
  • m 3 is 3, 4, 5, 6, 7 or 8;
  • R 41a , R 42a , R 4a , R 41b , R 42b and R 4b are each independently H or F; each time m 4a and m4 4b appear, they are each independently an integer selected from 1 to 9; Contains at least 4 F atoms in formula III-2;
  • m 4a and m4 4b are each independently an integer selected from 2 to 9 (such as 2, 3, 4, 5, 6, 7, 8 or 9);
  • m4a and m44b are each independently an integer selected from 2 to 8;
  • m4a and m44b are each independently an integer selected from 3 to 8;
  • m4a and m44b are each independently an integer selected from 3 to 6;
  • R 51 and R 52 are each independently H or F; each time m 5 appears, they are independently an integer selected from 2 to 10; Formula III-3 contains at least 4 F atoms;
  • n 5 is an integer selected from 3 to 10 (such as 3, 4, 5, 6, 7, 8, 9 or 10);
  • n 5 is an integer selected from 3 to 8;
  • m 5 is 3, 4, 5, 6, 7 or 8.
  • each occurrence of R 31 , R 32 and R 3 is F.
  • each occurrence of m 3 is independently an integer selected from 2 to 10.
  • m 3 is an integer selected from 3 to 10 (such as 3, 4, 5, 6, 7, 8, 9 or 10).
  • m 3 is an integer selected from 3 to 8.
  • m3 is 3, 4, 5, 6, 7, or 8.
  • each occurrence of R 41a , R 42a , R 4a , R 41b , R 42b , and R 4b is F.
  • m 4a and m 4 4b are each independently an integer selected from 2 to 9 (such as 2, 3, 4, 5, 6, 7, 8 or 9).
  • n 4a and m 4 4b are each independently an integer selected from 2 to 8.
  • n 4a and m 4 4b are each independently an integer selected from 3 to 8.
  • n 4a and m 4 4b are each independently an integer selected from 3 to 6.
  • each occurrence of R 51 and R 52 is F.
  • m 5 is an integer selected from 3 to 10 (such as 3, 4, 5, 6, 7, 8, 9 or 10).
  • m 5 is an integer selected from 3 to 8.
  • m5 is 3, 4, 5, 6, 7, or 8.
  • each time Rf appears the structure of Rf is as shown in Formula III-1.
  • each time Rf occurs the structure of Rf is as shown in Formula III-2.
  • each time Rf occurs the structure of Rf is as shown in Formula III-3.
  • the structure of formula III-1 is a linear saturated fluorinated aliphatic chain.
  • it can give the polymer layer better elasticity and prevent the polymer layer from cracking under large-volume deformation.
  • it can be made by the fluorine element. Effectively regulates the uniform deposition of lithium ions, inhibits the formation of lithium dendrites, and alleviates the volume expansion of the lithium anode side.
  • the structure of formula III-2 can be introduced with phosphorus element, and further when Z 2 is a bond (that is, does not exist), at this time, a phosphate group is formed between -(CH 2 CH 2 O) m -Rf.
  • the phosphate ester group has a flame retardant effect and is beneficial to improving the safety performance of the battery core.
  • Rf is a structure represented by formula III-1 or formula III-3.
  • -(CH 2 CH 2 O) m -Z 2 forms a phosphate group, which can exert a flame retardant effect and help improve the safety performance of the battery core.
  • Rf is a structure represented by formula III-1 or formula III-3.
  • -(CH 2 CH 2 O) m -Z 2 forms a phosphate group, which can exert a flame retardant effect and help improve the safety performance of the battery core.
  • a sulfonyl fluoride group can be introduced into the structure of formula III-3. It has a certain positive effect on improving the ionic conductivity of the polymer layer.
  • each occurrence of Formula III-1 has 0, 1, 2, 3 or 4 H atoms.
  • each occurrence of Formula III-1 has 0 H atoms.
  • the number of H atoms in each occurrence of Formula III-2 is 0, 1, 2, 3, 4, 5 or 6.
  • each occurrence of Formula III-2 has 0 H atoms.
  • each occurrence of Formula III-3 has 0, 1, 2, 3 or 4 H atoms.
  • each occurrence of Formula III-3 has 0 H atoms.
  • the number of H atoms By controlling the number of H atoms, the number of sites available for fluorine element substitution can be controlled.
  • each occurrence of Rf is independently selected from any of the following structures:
  • Rf 10 is a branched structure of Rf.
  • Rf 01 , Rf 02 , Rf 03 , Rf 04 , Rf 05 , Rf 06 , Rf 07 , Rf 08 and Rf 09 are all linear structures.
  • the side group structure in formula (I) is The side chain shown (where, Represents the attachment point to the carbon atom of the main chain), which can be recorded as an EO-Rf chain.
  • the chain length of the EO-Rf chain refers to the number of backbone atoms of the longest backbone connecting the carbonyl site and the terminal group in Rf.
  • the chain length of the EO-Rf chain is ⁇ 35, further, ⁇ 5, further ⁇ 6, further ⁇ 7, further ⁇ 8, further ⁇ 9, further ⁇ 10.
  • the chain length of the EO-Rf chain is ⁇ 30, further, ⁇ 5, further ⁇ 6, further ⁇ 7, further ⁇ 8, further ⁇ 9, further ⁇ 10.
  • the chain length of the EO-Rf chain can also be selected from any one or two of the following intervals: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 , 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, etc.
  • range of any two structures non-limiting examples of the chain length of the EO-Rf chain are 5 to 40, 5 to 35, 5 to 30, 6 to 40, 6 to 35, 6 to 30, 8 to 40 , 8 ⁇ 35, 8 ⁇ 30, 10 ⁇ 40, 10 ⁇ 35, 10 ⁇ 30, etc.
  • the EO-Rf chain is The chain length is 10;
  • the EO-Rf chain is The chain length is 16;
  • the EO-Rf chain is The chain length is 21;
  • the EO-Rf chain is The chain length is 29;
  • the EO-Rf chain is The chain length is 12;
  • the EO-Rf chain is When , the skeleton structure is branched, and the chain length at this time is 10.
  • each occurrence of X is independently H or an electron-withdrawing group containing 1 to 6 non-hydrogen atoms.
  • the number of non-hydrogen atoms can be selected from the range of any one or two of the following values: 1, 2, 3, 4, 5, and 6.
  • R 21 and R 22 are each independently H or methyl.
  • R 21 and R 22 are both methyl.
  • each occurrence of X independently, is -N(CH 3 ) 2 .
  • an electron-withdrawing group such as cyano group, etc.
  • each occurrence of A independently, is O, S, or NH.
  • each occurrence of A independently, is O or NH.
  • each occurrence of A is O.
  • each occurrence of A is NH.
  • the linker A can be composed of -COOH in the cyanoacrylic acid derivative monomer or its derived reactive form (such as acid chloride form, N-succinimide ester group activation form of the carboxyl group, etc.) and different reactive functional groups Reactive functional group pairs can then generate different types of chemical bonds through coupling reactions.
  • A when A is O, S or NH, it can be obtained through a coupling reaction between -COOH or its derived reactive form in the cyanoacrylic acid derivative monomer and -OH, -SH, or -NH 2 .
  • the diversification of A is the result of the flexible combination of reaction monomers.
  • Rf in Formula I is the same; each occurrence of X in Formula I is the same; and each occurrence of A in Formula I is the same.
  • Rf in Formula I is the same; X in Formula I is the same every time it appears; A in Formula I is the same every time it appears; further, Z2 in Formula I is the same every time it appears.
  • a single type of monomer (formula (II)) can be used to perform the polymerization reaction.
  • the general structure of the polymer Poly can be selected from the structures formed by polymerization of any monomer polymer in Table 1.
  • the molecular weight may be the same as or different from that for the polymers in Table 1.
  • Monomers corresponding to Example 1 in Table 1 For example, the structure formed by polymerization is: In formula I, X is H, A is O, m is 1, Z 2 is a bond, and Rf is The EO-Rf chain length is 10.
  • X is H and Rf is Further, A is O, further, Z 2 is a bond, further, m is a positive integer selected from 1 to 10, for example, m is 1.
  • monomers may be used at this time, in formula I, X is -N(CH 3 ) 2 , A is O, m is 3, Z 2 is a bond, and Rf is The EO-Rf chain length is 16.
  • X is -N(CH 3 ) 2 and Rf is Further, A is O, further, Z 2 is a bond, further, m is a positive integer selected from 1 to 10, for example, m is 3.
  • monomers may be used at this time, in formula I, X is H, A is O, m is 3, Z 2 is a bond, and Rf is The EO-Rf chain length is 21.
  • X is H and Rf is Further, A is O, further, Z 2 is a bond, further, m is a positive integer selected from 1 to 10, for example, m is 3.
  • X is H
  • A is O or NH
  • m is any integer selected from 1 to 1
  • Z2 is a bond
  • monomers may be used at this time, in formula I, X is -NO 2 , A is O, m is 1, Z 2 is a bond, and Rf is The EO-Rf chain length is 12.
  • X is -NO 2 and Rf is Further, A is O, further, Z 2 is a bond, further, m is a positive integer selected from 1 to 10, for example, m is 1.
  • X is H, A is O or NH (preferably O), and Rf is The definitions of m and Z 2 are consistent with the above.
  • A is 0; in another embodiment, A is NH.
  • monomers may be used at this time, in formula I, X is H, A is O, m is 8, Z 2 is a bond, and Rf is The EO-Rf chain length is 29.
  • X is H and Rf is Further, A is O, further, Z 2 is a bond, further, m is a positive integer selected from 1 to 10, for example, m is 8.
  • X is H, A is O or NH, and Rf is The definitions of m and Z 2 are consistent with the above.
  • A is 0; in another embodiment, A is NH.
  • n is an integer selected from 10 to 1000, preferably an integer selected from 10 to 950, further preferably an integer selected from 10 to 800, further preferably an integer selected from 15 to 800, and further Preferably it is an integer selected from 20 to 800, more preferably it is an integer selected from 40 to 800, still more preferably it is an integer selected from 50 to 800, still more preferably it is an integer selected from 100 to 800, still more preferably it is an integer selected from 10 to 800
  • the integer of 750 is preferably an integer selected from 15 to 750, further preferably an integer selected from 20 to 750, further preferably an integer selected from 40 to 750, further preferably an integer selected from 50 to 750, further preferably is an integer selected from 80 to 750, preferably an integer selected from 100 to 750, further preferably an integer selected from 10 to 600, further preferably an integer selected from 15 to 600, further preferably 20 to 600 is an integer, preferably an integer selected from 40 to 600, further preferably an integer selected from 50 to 600, further preferably an integer selected from 10 to
  • n can be selected from any one of the following values or an interval composed of any two values: 10, 20, 30, 40, 50, 60, 70, 80, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 850, 900, 950, 1000, etc.
  • the number average molecular weight of the polymer Poly is selected from 10 kDa to 200 kDa.
  • the number average molecular weight of the polymer Poly is selected from 50 kDa to 100 kDa.
  • the number average molecular weight of the polymer Poly can be selected from the range of any one of the following molecular weights or any two molecular weights (in kDa): 10, 11, 12, 13, 14, 15, 16 ,17,18,19,20,22,25,26,28,30,35,40,44,45,46,48,50,55,60,65,70,75,80,85,90,95 , 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, etc.
  • n in formula I is numerically equal to the degree of polymerization of the polymer Poly.
  • the molecular weight of the polymer Poly can be controlled.
  • the molecular chain length of the polymer Poly can be adjusted, which not only achieves effective wrapping of lithium-containing metals, but also maintains stable chemical connections, and can also affect the density and uniformity of the polymer layer.
  • the amount of lithium in the lithium-containing metal relative to the polymer Poly is greater than the amount of catalyst, on a molar ratio.
  • the lithium-containing metal can provide a catalyst amount, it can successfully catalyze the in-situ polymerization reaction of cyanoacrylic acid derivative monomers on the lithium metal surface.
  • the amount of lithium metal relative to the polymer Poly only requires the contact of the catalyst to catalyze the in-situ polymerization reaction of the cyanoacrylate monomer on the surface of the lithium metal.
  • the lithium-containing metal includes lithium metal or lithium alloy.
  • Lithium metal has the highest specific capacity (3860mAh/g) and the lowest electrochemical potential (-3.04V, relative to standard hydrogen electrode) among all negative electrode materials for lithium-based batteries. It is a better negative electrode material for lithium metal batteries. , helping to achieve high energy density.
  • the lithium alloy contains lithium and one or more of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel, titanium, etc.
  • the present application provides a negative electrode sheet, wherein the negative electrode sheet includes a negative electrode sheet base and a polymer layer distributed in a stack; the negative electrode sheet base includes a layer in contact with the polymer layer. a lithium-containing layer, the lithium-containing layer containing lithium, the polymer layer being chemically connected to at least a portion of the lithium in the lithium-containing layer;
  • the polymer layer includes the polymer Poly defined in the first aspect of this application.
  • the "negative electrode sheet matrix” can provide the negative electrode active material of the lithium metal battery.
  • the negative electrode sheet base in the negative electrode sheet at least includes a lithium-containing layer in contact with the polymer layer, that is, the lithium-containing layer is located at the outermost layer of the negative electrode sheet base. In other words, at least one side of the negative electrode sheet base The outermost layer is the lithium-containing layer.
  • the negative electrode plate base is composed of a lithium-containing layer.
  • the polymer layer is chemically connected to at least a portion of the lithium in the lithium-containing layer.
  • “chemical connection” here refers to covalent connection.
  • the thickness of the negative electrode sheet base may be the thickness of the lithium negative electrode in a common lithium metal battery.
  • the “lithium anode” here refers to the thickness of the anode active material layer provided by lithium metal or lithium alloy.
  • the non-limiting thickness of the lithium-containing layer is, for example, 5 ⁇ m to 40 ⁇ m.
  • the thickness of the lithium-containing layer can also be selected from the range of any one of the following thicknesses or any two thicknesses: 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 15 ⁇ m. , 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 40 ⁇ m, etc.
  • lithium-containing layer refers to a structural layer containing metallic lithium.
  • the lithium-containing layer may be essentially composed of lithium (Li) metal, may also be a lithium alloy, or may be a composition containing lithium metal and a lithium alloy (for example, a composition consisting essentially of lithium metal and a lithium alloy).
  • Lithium in the lithium-containing layer can play multiple roles. On the one hand, it can catalyze the in-situ polymerization of cyanoacrylic acid derivative monomers. On the other hand, it can form stable covalent connections with the cyano groups carried by the polymer Poly. On the other hand, it can also be used as a lithium source for negative active materials.
  • the thickness of the lithium-containing layer can be any suitable thickness, as long as it is sufficient to provide a catalyst amount that can support the in-situ polymerization reaction of the cyanoacrylic acid derivative monomer.
  • it can also be the lithium negative electrode in a common lithium metal battery. thickness.
  • a second negative electrode active material layer can also be provided on the side of the lithium-containing layer away from the polymer layer.
  • the negative electrode sheet base includes the lithium-containing layer and the second negative electrode active material layer.
  • the composition and content of the lithium-containing layer and the second negative active material layer may be the same or different.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side of the negative electrode sheet.
  • the flexible polymer layer can closely fit on the surface of the lithium-containing layer and can play a role at the negative electrode of the lithium metal battery.
  • the function of the protective layer can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • the amount of lithium in the lithium-containing layer relative to the polymer Poly is greater than the amount of catalyst, on a molar ratio.
  • sufficient lithium (much greater than the amount of catalyst) needs to be provided in the negative electrode sheet to greatly increase the energy density of the battery core, while also ensuring the first Coulombic efficiency of the negative electrode and reducing or avoiding lithium consumption of the positive electrode.
  • the lithium-containing layer includes lithium metal or lithium alloy.
  • the lithium alloy contains lithium and one or more of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel and titanium.
  • the lithium-containing layer consists essentially of lithium metal.
  • the lithium-containing layer is a lithium alloy.
  • the polymer layer further contains electrolyte. This is helpful to provide better ionic conductivity.
  • the electrolyte contains lithium salt and electrolyte solvent.
  • the lithium salt is selected from lithium hexafluorophosphate (LiPF 6 ), tetrafluoroboric acid (LiBF 4 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), One or more of lithium difluorooxalate borate (LiDFOB), lithium perchlorate (LiClO 4 ), and lithium dioxalate borate (LiBOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 tetrafluoroboric acid
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonyl imide
  • LiDFOB lithium difluorooxalate borate
  • LiClO 4 lithium perchlorate
  • LiBOB lithium dioxalate borate
  • the electrolyte solvent is selected from ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) , dipropyl carbonate (DPC), diphenyl carbonate (DPhC), dibutyl carbonate (DBC), butylene carbonate (BC), ethylene glycol dimethyl ether (DME), tetrahydrofuran (THF), dioxygen Pentacyclic (DOL), methyl nonafluoro-n-butyl ether (MFE), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458), One of octafluoropentyl-tetrafluoroethyl ether (F-EAE), 1,2-di(cyanoethoxy)ethane (DENE), diphenyl ether (DPE) and 18
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 5 mol/L.
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 4 mol/L.
  • the concentration of the lithium salt in the electrolyte is selected from 2 mol/L to 4 mol/L.
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 3 mol/L.
  • the concentration of the lithium salt in the electrolyte is selected from 0.5 mol/L to 2 mol/L.
  • the concentration of the lithium salt in the electrolyte can be selected from the following range of any one value or two values (unit: mol/L): 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, etc.
  • the concentration of lithium salt in the electrolyte also affects the deposition morphology of lithium ions.
  • the concentration of lithium salt will change the solvation effect of Li + in the electrolyte, thereby affecting the composition of the solid electrolyte interface film (SEI film) and the deposition morphology of lithium ions.
  • SEI film solid electrolyte interface film
  • the lithium salt in the electrolyte at an appropriate concentration, it can be achieved Dense and uniform deposition of lithium ions and small volume expansion.
  • the polymer layer can also have appropriate mechanical properties, avoid excessive lithium salt concentration that is detrimental to mechanical properties, and achieve better performance during charging and discharging. Lithium ion conductivity to avoid poor lithium ion conductivity due to insufficient lithium salt concentration.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:2.
  • “9:1 to 1:2" and (9 ⁇ 0.5):1 have the same meaning and can be used interchangeably.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:1.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1:2.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1:1.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1.5:1.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 4:1 to 1.5:1.
  • the mass ratio of the polymer Poly to the electrolyte can also be 9:1, 8.5:1, 8:1, 7.5:1, 7:1, 6.5:1, 6:1, 5.5:1, 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, 0.9:1, 0.8:1, 0.7:1, 0.6: 1, 0.5:1, etc. It can also be selected from the interval composed of any two ratios mentioned above. Such as (9 ⁇ 2):1 etc.
  • the mass proportion of the electrolyte in the polymer layer is selected from 9.5% to 65%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 10% to 60%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 20% to 60%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 30% to 60%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 9.5% to 50%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 10% to 50%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 20% to 50%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 30% to 45%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 9.5% to 45%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 10% to 45%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 20% to 45%.
  • the mass proportion of the electrolyte in the polymer layer is selected from 30% to 50%.
  • the mass proportion of the electrolyte in the polymer layer can be selected from any one of the following percentages or an interval composed of any two percentages: 9.5%, 10%, 11%, 12%, 14%, 15 %, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, etc.
  • intervals composed of any two percentages include 9% to 55%, 9.5% to 50%, etc.
  • the mass ratio of the electrolyte in the polymer layer can be adjusted by controlling the mass ratio of the polymer Poly and the electrolyte within an appropriate range.
  • the mass proportion of electrolyte in the polymer layer will affect the elasticity and ionic conductivity of the protective layer.
  • the presence of a certain amount of lithium salt and solvent has a plasticizing effect on the polymer layer and can improve the elasticity of the polymer layer.
  • lithium salts and solvents are incorporated into the polymer layer.
  • the polymer layer On a microscopic scale, the polymer layer has a sponge-like loose porous structure, and the pores are filled with electrolyte to provide subsequent lithium ions. Provides a path for transmission.
  • the thickness of the polymer layer is selected from 5 nm to 10 ⁇ m.
  • the thickness of the polymer layer is selected from 50 nm to 8 ⁇ m.
  • the thickness of the polymer layer is selected from 50 nm to 5 ⁇ m.
  • the thickness of the polymer layer is selected from 100 nm to 5 ⁇ m.
  • the thickness of the polymer layer can be selected from the following range of any one thickness or any two thicknesses: 5nm, 5.5nm, 6nm, 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, 9nm, 9.5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1 ⁇ m, 1. 5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, etc.
  • the structure of the polymer layer on the surface of lithium-containing metal can be controlled at the nanometer scale, which is beneficial to the assembled battery core showing smaller interface resistance.
  • the elastic modulus of the polymer layer ranges from 0.1 MPa to 70 MPa.
  • the elastic modulus of the polymer layer ranges from 0.5 MPa to 50 MPa.
  • the elastic modulus of the polymer layer ranges from 1 MPa to 50 MPa.
  • the elastic modulus of the polymer layer ranges from 10 MPa to 50 MPa.
  • the elastic modulus of the polymer layer is selected from 10 MPa to 47 MPa.
  • the elastic modulus of the polymer layer ranges from 10 MPa to 45 MPa.
  • the elastic modulus of the polymer layer is selected from 20 MPa to 45 MPa.
  • the elastic modulus of the polymer layer can be selected from any one of the following values or an interval composed of any two values: 0.1MPa, 0.2MPa, 0.5MPa, 0.8MPa, 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 12MPa, 14MPa, 15MPa, 16MPa, 18MPa, 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, 50MPa, 60MPa, 65MPa, 70MPa, etc.
  • Non-limiting examples of the elastic modulus of the polymer layer are: 0.5MPa ⁇ 70MPa, 1MPa ⁇ 70MPa, 15MPa ⁇ 70MPa, 20MPa ⁇ 70MPa, 20MPa ⁇ 50MPa, 0.1MPa ⁇ 47MPa, 0.5MPa ⁇ 47MPa, 1MPa ⁇ 47MPa, 15MPa ⁇ 47MPa, 20MPa ⁇ 47MPa, 0.1MPa ⁇ 45MPa, 0.5MPa ⁇ 45MPa, 1MPa ⁇ 45MPa, 15MPa ⁇ 45MPa, 15MPa ⁇ 45MPa, etc.
  • the elastic modulus of the polymer layer refers to the elastic modulus at 25°C.
  • the elastic deformation of the polymer layer ranges from 50% to 700%.
  • the elastic deformation of the polymer layer ranges from 50% to 400%.
  • the elastic deformation range of the polymer layer is 50% to 300%.
  • the elastic deformation range of the polymer layer is 80% to 300%.
  • the elastic deformation range of the polymer layer is 80% to 265%.
  • the elastic deformation of the polymer layer ranges from 100% to 700%.
  • the elastic deformation range of the polymer layer is 100% to 600%.
  • the elastic deformation range of the polymer layer is 100% to 400%.
  • the elastic deformation range of the polymer layer is 100% to 300%.
  • the elastic deformation range of the polymer layer is 100% to 250%.
  • the elastic deformation range of the polymer layer is 100% to 200%.
  • the elastic deformation range of the polymer layer is 100% to 190%.
  • the elastic deformation range of the polymer layer can be selected from the following range of any one percentage or two percentages: 50%, 55%, 60%, 65%, 70%, 80%, 90% ,100%,150%,200%,220%,240%,250%,260%,265%,270%,280%,300%,350%,400%,450%,500%,600%,700 %wait.
  • Non-limiting examples of the elastic deformation range of the polymer layer are: 50% to 265%, 50% to 250%, 80% to 700%, 80% to 600%, 80% to 500%, 80% to 400% , 100% ⁇ 500%, 100% ⁇ 265%, etc.
  • the elastic deformation range of the polymer layer refers to the elastic deformation range at 25°C.
  • the swelling rate of the polymer layer at 25°C is selected from 10% to 60%.
  • the swelling rate of the polymer layer is selected from 15% to 60%.
  • the swelling rate of the polymer layer is selected from 15% to 55%.
  • the swelling rate of the polymer layer is selected from 15% to 45%.
  • the swelling rate of the polymer layer is selected from 20% to 45%.
  • the swelling rate of the polymer layer is selected from 20% to 40%.
  • the swelling rate of the polymer layer is selected from 25% to 50%.
  • the swelling rate of the polymer layer can be selected from the following range of any one percentage or any two percentages: 10%, 11%, 12%, 14%, 15%, 16% , 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, etc.
  • non-limiting examples of the swelling rate of the polymer layer include 20% to 60%, 10% to 55%, 20% to 55%, 10% to 45%, 10% to 40%, 15% to 40% etc.
  • the swelling rate of the polymer layer refers to the swelling rate at 25°C. Please refer to the test methods of "Structure and Performance Testing" in the Examples section below.
  • the ionic conductivity of the swollen polymer layer is selected from 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -6 S/cm.
  • the ionic conductivity of the swollen polymer layer is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -6 S/cm.
  • the ion conductivity of the swollen polymer layer is selected from 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -5 S/cm.
  • the ionic conductivity of the swollen polymer layer is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -5 S/cm.
  • the ion conductivity of the swollen polymer layer is selected from 8 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm.
  • the ionic conductivity of the swollen polymer layer is selected from 5 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm.
  • the ionic conductivity of the swollen polymer layer is selected from 3 ⁇ 10 -3 S/cm to 1 ⁇ 10 -4 S/cm.
  • the ionic conductivity of the swollen polymer layer is selected from 3 ⁇ 10 -3 S/cm to 5 ⁇ 10 -4 S/cm.
  • the ionic conductivity of the swollen polymer layer can be selected from any one of the following values or any two ranges: 8 ⁇ 10 -3 S/cm, 7 ⁇ 10 -3 S/cm, 6 ⁇ 10 -3 S/cm, 5 ⁇ 10 -3 S/cm, 4.5 ⁇ 10 -3 S/cm, 4 ⁇ 10 -3 S/cm, 3.5 ⁇ 10 -3 S/cm, 3 ⁇ 10 -3 S/cm, 2.5 ⁇ 10 -3 S/cm, 2 ⁇ 10 -3 S/cm, 1.5 ⁇ 10 -3 S/cm, 1 ⁇ 10 -3 S/cm, 9 ⁇ 10 -4 S /cm, 8 ⁇ 10 -4 S/cm, 7 ⁇ 10 -4 S/cm, 6 ⁇ 10 -4 S/cm, 5 ⁇ 10 -4 S/cm, 4 ⁇ 10 -4 S/cm, 3 ⁇ 10 -4 S/cm, 2 ⁇ 10 -4 S/cm, 1 ⁇ 10 -4 S
  • the ionic conductivity of the swollen polymer layer refers to the ionic conductivity at 25°C.
  • the volume expansion rate of the negative electrode piece is less than 92%, and further, is selected from 6% to 92%.
  • the volume expansion rate of the negative electrode piece can also be selected from the following range of any one percentage or any two percentages: 6%, 7%, 8%, 9%, 10%, 11%, 12%, 14%, 15%, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% , 90%, 92%, etc.
  • the volume expansion rate of the pole piece refers to the volume expansion rate at 25°C.
  • the negative electrode sheet substrate further includes a negative electrode current collector; the negative electrode current collector is located on a side of the lithium-containing layer away from the polymer layer.
  • the negative electrode current collector is provided with or without a second negative electrode active material layer between the negative electrode current collector and the lithium-containing layer. Further, the second negative electrode active material layer and The components in the lithium-containing layer may be the same or different.
  • a lithium-containing layer is provided only on the outermost layer on one side of the negative electrode base (see Figures 1, 2 and 3).
  • lithium-containing layers are provided on the outermost layers on both sides of the negative electrode base (see Figures 4 and 5).
  • the lithium-containing layers on both sides may contain the same or different amounts of lithium.
  • the lithium content in the lithium-containing layer may refer to the aforementioned definition.
  • the lithium content in the second negative electrode active material may be selected from the lithium content in the negative electrode active material layer of a general lithium metal battery.
  • Non-limiting examples of the second negative active material layer include lithium metal, lithium alloy, or a combination thereof.
  • the "second negative electrode active material layer” can select any suitable negative electrode active material layer among the reported active material layers of lithium metal batteries.
  • the second negative electrode active material layer may be essentially composed of lithium (Li) metal, may also be a lithium alloy, or may be a combination essentially composed of lithium metal and lithium alloy.
  • lithium-containing layers are provided on the outermost layers of both sides of the negative electrode sheet base, and polymer layers are provided on the surfaces of the lithium-containing layers on both sides (see Figures 4 and 5);
  • the chemical composition and content of the polymer layers can be the same or different.
  • the negative electrode plate includes a structure as shown in FIG. 1 , including a lithium-containing layer 130 and a polymer layer 200 distributed in a stack.
  • the lithium-containing layer contains lithium, lithium alloy, or a combination of both.
  • the lithium-containing layer here serves as the negative active material layer;
  • the polymer layer contains polymer Poly, which carries a large number of cyano groups. These cyano groups are related to the lithium-containing layer.
  • the lithium in the layer is covalently bonded to form a stable chemical connection, allowing the polymer layer to be firmly connected to the surface of the lithium-containing layer.
  • the polymer Poly may be selected from the polymer Poly described in any embodiment of the first aspect.
  • the definition of electrolyte is as mentioned above.
  • the negative electrode sheet includes a structure as shown in Figure 2, including a stacked distribution of the negative electrode sheet base 100 and a polymer layer 200; the negative electrode sheet base 100 includes a sequentially stacked distribution of the negative electrode current collector 110 and lithium-containing Layer 130 , the polymer layer 200 is located on the surface of the lithium-containing layer 130 away from the negative electrode current collector 110 .
  • the polymer layer contains polymer Poly and electrolyte.
  • the lithium-containing layer contains lithium, lithium alloy or a combination of both, and the polymer layer contains polymer Poly, which carries a large number of cyano groups. These cyano groups are covalently combined with the lithium in the lithium-containing layer to form a stable The chemical connection makes the polymer layer firmly connected to the surface of the negative electrode base.
  • the negative electrode sheet includes a structure as shown in FIG. 3 , including a stacked and distributed negative electrode sheet base 100 and a polymer layer 200; the negative electrode sheet base 100 includes a sequentially stacked and distributed negative electrode current collector 110, and the second The negative electrode active material layer 120 and the lithium-containing layer 130, the polymer layer is located on the surface of the lithium-containing layer 130 away from the negative electrode current collector 110.
  • the negative electrode sheet includes a structure as shown in Figure 4, including a negative electrode sheet base 100 and two polymer layers 200 respectively disposed on both sides of the negative electrode sheet base 110; the negative electrode base sheet base includes a negative electrode Current collector 110, and two lithium-containing layers 130 respectively disposed on both sides of the negative electrode current collector 110.
  • the lithium-containing layers 130 on both sides of the negative electrode piece are directly connected to the corresponding polymer layers 200 (through covalent interaction). chemical connection).
  • the chemical composition and content of the polymer layers 130 on both sides may be the same or different.
  • the chemical composition and content of the lithium-containing layers 130 on both sides may be the same or different.
  • the negative electrode sheet includes a structure as shown in Figure 5, including a negative electrode sheet base 100 and two polymer layers 200 respectively disposed on both sides of the negative electrode sheet base 110; the negative electrode base sheet base includes a negative electrode
  • the current collector 110 has two second negative electrode active material layers 120 respectively disposed on both sides of the negative electrode current collector 110 , and two second negative electrode active material layers 120 respectively disposed on one surface of the two second negative electrode active material layers 120 away from the negative electrode current collector 110 .
  • the lithium layer 130 and the lithium-containing layer 130 on both sides of the negative electrode plate are directly connected to the corresponding polymer layer 200 (chemical connection is achieved through covalent interaction).
  • the chemical composition and content of the polymer layers 130 on both sides may be the same or different.
  • the chemical composition and content of the second negative active material layer 120 on both sides may be the same or different.
  • the chemical composition and content of the lithium-containing layers 130 on both sides may be the same or different.
  • the negative electrode sheet generally includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode film layer includes the aforementioned lithium-containing layer, and also includes a polymer layer formed on at least one surface of the lithium-containing layer away from the inside of the negative electrode film layer. That is, the polymer layer is located on the lithium-containing layer away from the inside of the negative electrode film layer.
  • a polymer layer is located on the outermost layer of the negative electrode sheet. Furthermore, the polymer layer and the lithium-containing layer are chemically connected through covalent interactions.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base material.
  • the composite current collector can be formed by forming metal materials (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative active material in the negative active material layer may be a negative active material known in the art for lithium metal batteries.
  • the negative active material suitable for the present application may include one or more of lithium metal and lithium alloy.
  • lithium alloys may also contain one or more of silver, magnesium, aluminum, gold, zinc, tin, copper, nickel, titanium, etc.
  • the lithium-containing layer in this application can serve as the first negative electrode active material layer, and a second negative electrode active material layer can be provided between the lithium-containing layer and the negative electrode current collector.
  • the composition and content of the second negative active material layer may be the same as or different from the composition and content of the lithium-containing layer.
  • the negative electrode film layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), polysodium acrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer optionally further includes a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode film layer optionally includes other auxiliaries, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the present application provides an electrode assembly, which includes a positive electrode piece, an isolation film, and the negative electrode piece described in the second aspect of the application.
  • the isolation film is disposed on the negative electrode piece and the positive electrode piece. between; the polymer layer is provided at least on the surface of the negative electrode plate base body close to the side of the isolation film.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side of the negative electrode sheet in the electrode assembly.
  • the flexible polymer layer can closely adhere to the surface of the lithium-containing layer and can be used in lithium metal batteries.
  • the negative electrode acts as a protective layer, which can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • a lithium-containing layer is provided on the outermost layer on one side of the negative electrode sheet base.
  • lithium-containing layers are provided on the outermost layers on both sides of the negative electrode sheet base.
  • the lithium-containing layers on both sides may contain the same or different amounts of lithium.
  • lithium-containing layers are provided on the outermost layers on both sides of the negative electrode sheet base, and polymer layers are provided on the surfaces of the lithium-containing layers on both sides.
  • the chemical composition and content of the polymer layers on both sides can be Same or different.
  • this application provides a secondary battery, which includes a cell electrolyte and the electrode assembly described in the third aspect of this application, and the cell electrolyte is disposed between the polymer layer and the positive electrode piece.
  • a dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer on at least one side surface of the negative electrode sheet in the secondary battery.
  • the flexible polymer layer can be closely attached to the surface of the lithium-containing layer and can be used on lithium metal.
  • the negative electrode of the battery acts as a protective layer, which can effectively inhibit the contact reaction between the electrolyte and lithium, reduce the consumption of electrolyte and lithium, improve the Coulombic efficiency, and extend the cycle life.
  • a secondary battery typically includes a positive electrode plate, a negative electrode plate, a cell electrolyte and a separator.
  • active ions are inserted and detached back and forth between the positive and negative electrodes.
  • the cell electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • the isolation film is placed between the positive electrode piece and the negative electrode piece. It mainly prevents the positive and negative electrodes from short-circuiting and allows ions to pass through.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.
  • the positive electrode current collector has two surfaces opposite in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the cathode active material may be a cathode active material known in the art for batteries.
  • the cathode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also referred to as NCM 523 ),
  • LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (can also be abbreviated to NCM 811 ) , at least one of lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and its modified compounds.
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), composites of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), phosphoric acid At least one of a composite material of lithium manganese and carbon, a composite material of lithium manganese iron phosphate, or a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • composites of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate
  • phosphoric acid At least one of a composite material of lithium manganese and carbon, a composite material of lithium manganese iron phosphate, or a composite material of lithium manganese iron phosphate and carbon.
  • the positive electrode film layer optionally further includes a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive electrode film layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components in a solvent (such as N - methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode piece can be obtained.
  • a solvent such as N - methylpyrrolidone
  • the cell electrolyte plays a role in conducting ions between the positive and negative electrodes.
  • This application has no specific restrictions on the type of battery core electrolyte, which can be selected according to needs.
  • the cell electrolyte can be liquid, gel, or fully solid.
  • the cell electrolyte uses a second electrolyte.
  • the second electrolyte solution includes electrolyte salt and solvent.
  • the composition of the electrolyte and the electrolyte in the polymer layer may be the same or different.
  • the electrolyte salt may be selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, lithium bistrifluoromethanesulfonimide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluoroborate, lithium dioxaloborate, lithium difluorodioxalate phosphate and lithium tetrafluoroxalate phosphate.
  • the solvent may be selected from the group consisting of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, Butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the cell electrolyte optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • isolation film and “separator” have the same meaning and can be used interchangeably.
  • the secondary battery further includes a separator film.
  • a separator film There is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the positive electrode piece, the negative electrode piece and the separator film can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer packaging.
  • the outer packaging can be used to package the above-mentioned electrode components and battery core electrolytes.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 6 shows a square-structured secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 51 has an opening communicating with the accommodation cavity, and the cover plate 53 can cover the opening to close the accommodation cavity.
  • the positive electrode piece, the negative electrode piece and the isolation film can be formed into the electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the components of the cell electrolyte and the electrolyte in the polymer layer may be the same or different.
  • the composition of the cell electrolyte in the secondary battery and the electrolyte in the polymer layer are the same, the consistency of lithium ion transmission in the cell can be maintained and the interference of multiple factors such as electrolyte solvation and interface side reactions can be reduced.
  • the formation of stable SEI can be induced directionally on the side of the lithium-containing layer, thereby regulating the deposition morphology of lithium ions.
  • the charging current density of the secondary battery is selected from 0.3mA/cm 2 to 12mA/cm 2 .
  • the charging current density of the secondary battery is selected from 1 mA/cm 2 to 10 mA/cm 2 .
  • the charging current density of the secondary battery is selected from 1 mA/cm 2 to 6 mA/cm 2 .
  • the charging current density of the secondary battery is selected from 1 mA/cm 2 to 3 mA/cm 2 .
  • the charging current density of the secondary battery can be selected from any one of the following values or an interval composed of any two values: 0.3mA/cm 2 , 0.4mA/cm 2 , 0.5mA/cm 2 , 0.6mA /cm 2 , 0.7mA/cm 2 , .8mA/cm 2 , 0.9mA/cm 2 , 1mA/cm 2 , 1.5mA/cm 2 , 2mA/cm 2 , 2.5mA/cm 2 , 3mA/cm 2 , 3.5 mA/cm 2 , 4mA/cm 2 , 4.5mA/cm 2 , 5mA/cm 2 , 5.5mA/cm 2 , 6mA/cm 2 , 7mA/cm 2 , 8mA/cm 2 , 9mA/cm 2 , 10mA/cm 2 , 11mA/cm 2 , 12mA
  • the applicable charging current density may also be 0.3mA/cm 2 ⁇ 0.5mA/cm 2 , 0.5mA/cm 2 ⁇ 1mA/cm 2 , 1mA/cm 2 ⁇ 1.5mA/cm 2 , 1.5mA /cm 2 ⁇ 2mA/cm 2 , 2mA/cm 2 ⁇ 2.5mA/cm 2 , 2.5mA/cm 2 ⁇ 3mA/cm 2 , 3mA/cm 2 ⁇ 3.5mA/cm 2 , 3.5mA/cm 2 ⁇ 4mA/ cm 2 , 4mA/cm 2 ⁇ 4.5mA/cm 2 , 4.5mA/cm 2 ⁇ 5mA/cm 2 , 5mA/cm 2 ⁇ 5.5mA/cm 2 , 5.5mA/cm 2 ⁇ 6mA/cm 2 , 6mA/cm 2 ⁇ 8mA/cm 2 , 8mA/cm 2
  • the secondary battery provided by the present application can be cycled under the aforementioned charging current density conditions.
  • the capacity retention rate of the secondary battery after 50 cycles is selected from 85% to 97%.
  • the capacity after 50 cycles can also be selected from any one of the following percentages or an interval composed of any two percentages: 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, etc.
  • the "capacity retention rate after 50 cycles" of the secondary battery refers generally to the test value under the conditions of 20°C to 30°C, unless otherwise specified.
  • the capacity retention rate of the secondary battery after 50 cycles refers to the volume expansion rate at 25°C.
  • the present application provides a battery module, which includes the secondary battery described in the fourth aspect of the present application.
  • secondary batteries can be assembled into battery modules, and the number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 8 shows the battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space in which a plurality of secondary batteries 5 are received.
  • the above-mentioned battery modules can also be assembled into a battery pack.
  • the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery pack.
  • the present application provides a battery pack, which includes the battery module described in the fifth aspect of the present application.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • this application provides an electrical device, which includes one of the secondary battery described in the fourth aspect of this application, the battery module described in the fifth aspect of this application, and the battery pack described in the sixth aspect of this application, or Various.
  • the electrical device includes at least one of the secondary battery, battery module, or battery pack provided by the present application.
  • the secondary battery, battery module, or battery pack may be used as a power source for the electrical device, or may be used as an energy storage unit for the electrical device.
  • the electrical devices may include mobile equipment, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • mobile devices can be, for example, mobile phones, laptops, etc.; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc. , but not limited to this.
  • a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.
  • FIG. 11 shows an electrical device 6 as an example.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the device may be a mobile phone, a tablet, a laptop, etc.
  • the device is usually required to be thin and light, and a secondary battery can be used as a power source.
  • the present application provides the use of monomeric compound II in preparing negative electrode sheets, wherein the structure of monomeric compound II is as shown in formula II:
  • Rf, A, Z 2 , X and m are respectively as defined in the first aspect of this application.
  • Non-limiting examples of monomeric compounds II are shown in Table 1.
  • the monomer compound II contacts the lithium in the lithium-containing layer of the negative electrode base and is polymerized in situ to form a polymer layer.
  • the monomer compound II is a cyanoacrylic acid derivative compound, in which the cyano group can contact with the lithium in the outermost layer of the negative electrode plate matrix to form a chemical connection, and the carbon-carbon double bond in it can be catalyzed by lithium.
  • the polymer is reacted to prepare the polymer-modified lithium material described in the first aspect of the present application. At this time, a firmly connected, tightly fitting, dense and uniform flexible polymer layer is formed on the surface of the lithium-containing layer, which can exert The aforementioned protective layer function.
  • the present application provides a method for preparing a negative electrode sheet, which includes the following steps:
  • a negative electrode plate base body the outermost layer of at least one side of the negative electrode plate base body is a lithium-containing layer, and the lithium-containing layer includes lithium-containing metal; also provide a reaction mixture containing monomer compound II and electrolyte;
  • the reaction mixture is coated on the surface of the lithium-containing layer on at least one side of the negative electrode sheet substrate, and the monomer compound II is polymerized in situ to form a polymer layer;
  • Rf, A, Z 2 , X and m are respectively as defined in the first aspect of this application;
  • the electrolyte is as defined in the second aspect of this application.
  • the definition of the negative electrode plate substrate provided in this aspect may refer to the aforementioned definition.
  • the negative electrode sheet substrate provided in this aspect at least includes a lithium-containing layer capable of contacting the monomer compound II to catalyze the in-situ polymerization reaction.
  • the cyano group in the monomer compound II can contact with the lithium in the outermost layer of the negative electrode sheet matrix to form a chemical connection (covalent connection), and the carbon-carbon double bond can occur under the catalysis of lithium.
  • the in-situ polymer reaction forms the polymer Poly represented by the aforementioned formula I, thereby preparing the polymer-modified lithium material described in the first aspect of the present application.
  • a firmly connected, closely fitting, and The dense and uniform flexible polymer layer can play the role of the protective layer mentioned above.
  • the coating is not only stably bonded to the surface of the lithium-containing layer through chemical connection to avoid falling off from the surface of the lithium-containing layer during charging and discharging, but also the coating is dense and uniform, and the coating can be The thickness is controlled at the nanometer scale, and the assembled battery core can exhibit smaller interface resistance.
  • the negative electrode sheet matrix can be prepared by dispersing the above-mentioned components used to prepare the negative electrode sheet, such as negative active materials, conductive agents, binders and any other components in a solvent (such as (ionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode plate matrix can be obtained.
  • a solvent such as (ionized water
  • the application provides that the monomeric compound II is contacted with at least a catalytic amount of lithium in the lithium-containing metal. On the one hand, it provides chemical connection sites for the polymer layer, and on the other hand, it effectively catalyzes the in-situ polymerization of cyanoacrylic acid derivative monomers.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:2.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 9:1 to 1:1.
  • the mass ratio of the polymer Poly and the electrolyte is selected from 5:1 to 1:1.
  • the mass ratio of the monomer compound II and the electrolyte is selected from 5:1 to 1.5:1.
  • the mass ratio of the monomer compound II and the electrolyte is selected from 4:1 to 1.5:1.
  • the mass ratio of the polymer Poly and the electrolyte can also be any one of the following ratios or selected from the range of any two ratios: 9:1, 8:1, 7:1 , 6:1, 5:1, 4:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, 1:1.5, etc.
  • the mass ratio of the monomer compound II and the electrolyte By controlling the mass ratio of the monomer compound II and the electrolyte, the mass ratio of the polymer Poly and the electrolyte in the generated polymer layer can be controlled.
  • the coating method is selected from the group consisting of coating, spraying, and spin coating. and any of the vapor deposition methods.
  • the reaction temperature of the in-situ polymerization is selected from 30°C to 100°C.
  • the reaction temperature of the in-situ polymerization is selected from 30°C to 50°C.
  • the reaction temperature of the in-situ polymerization is selected from 40°C to 60°C.
  • the reaction temperature of in-situ polymerization can be selected from any one of the following values or an interval composed of any two values: 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.
  • the reaction time of the in-situ polymerization is selected from 0.1 h to 24 h.
  • reaction time of the in-situ polymerization is selected from 0.1h to 12h.
  • the reaction time of the in-situ polymerization is selected from 0.1 h to 6 h.
  • the reaction time of in-situ polymerization can be selected from any one of the following time lengths or an interval consisting of any two time lengths: 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.8h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 11h, 12h , 14h, 15h, 16h, 18h, 20h, 21h, 22h, 24h, etc.
  • the coating thickness of the reaction mixture is selected from 100 nm to 8 ⁇ m.
  • the coating thickness of the reaction mixture is selected from 50 nm to 5 ⁇ m.
  • the coating thickness of the reaction mixture is selected from 50 nm to 8 ⁇ m.
  • the coating thickness of the reaction mixture can be selected from the following range of any one value or two values: 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1 ⁇ m , 1.5 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, etc.
  • the polymer layer formed is as defined in the second aspect of the application.
  • the negative electrode sheet base is a pure lithium sheet.
  • the battery negative electrode piece can also introduce an additional negative electrode current collector to facilitate the assembly of the tab, or a pure lithium piece covered with a polymer layer can be used as the negative electrode piece.
  • the negative electrode sheet substrate further includes a negative electrode current collector; the negative electrode current collector is located on a side of the lithium-containing layer away from the polymer layer.
  • a second negative active material layer may or may not be provided between the negative current collector and the lithium-containing layer, and the components in the second negative active material layer and the lithium-containing layer may Same or different.
  • the method of forming the second active material layer or the lithium-containing layer on the negative electrode current collector may be selected from: (1) transferring lithium metal or lithium alloy rolled by rolling to the negative electrode current collector. Method; (2) Method of evaporating lithium metal or lithium alloy on the negative electrode current collector, etc.
  • the method of forming the lithium-containing layer on the second active material layer may be selected from: (1) a method of transferring lithium metal or lithium alloy rolled by rolling onto the second active material layer; (2) Methods of evaporating lithium metal or lithium alloy on the second active material layer, etc.
  • the present application provides a method for preparing a secondary battery, wherein the secondary battery is the secondary battery described in the fourth aspect of the application, and the preparation method includes the following steps:
  • the cell electrolyte is injected into the battery case of the electrode assembly.
  • the parameter characterization mentioned above includes but is not limited to elastic modulus, elastic deformation range, polymer swelling rate, ionic conductivity, flexibility test, pole piece expansion rate, battery cycle performance, etc. You can use or refer to the test methods below Implementation, including but not limited to the "Structural and Performance Testing" section.
  • room temperature refers to 20°C to 30°C.
  • the coating method of the monomer-electrolyte mixture is a coating method.
  • the fluorinated monomer used in the following examples can be purchased commercially or prepared by the following method.
  • those skilled in the art can use (but not limited to) Fourier transform infrared spectroscopy (FT-IR) testing, 1 H NMR testing, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and other methods to conduct structural characterization to confirm whether the structure of the synthesized product conforms to the structural design, which is achievable by those skilled in the art.
  • FT-IR Fourier transform infrared spectroscopy
  • 1 H NMR 1 H NMR testing
  • GPC gel permeation chromatography
  • XPS X-ray photoelectron spectroscopy
  • Step 1 Prepare side chain molecule Cp3: polyethylene glycol terminated by compound Cp1(PA- AH , A is O or NH, AH is OH or NH 2 , PA is the protective group of AH, corresponding to the hydroxyl protective group or Amino protecting group) and Cp2 undergo condensation or addition reaction to prepare compound Cp31, and then remove the protecting group PA of AH to obtain compound Cp3.
  • Reaction conditions may refer to existing methods in the field of organic chemistry. Those skilled in the art can easily implement this.
  • reaction formula in step one is as follows:
  • Step 2 taking X as H as an example, you can refer to the following reaction formula to prepare the fluorinated monomer shown in Formula II-1:
  • Step 2 taking X as -N(CH 3 ) 2 as an example, you can refer to the following reaction formula to prepare the fluorinated monomer shown in Formula II-1:
  • Whether the product compound is formed can be determined based on at least one of a molecular weight test result and a viscosity test result.
  • LiFSI Lithium bisfluorosulfonyl imide
  • Isolation film Use polypropylene film.
  • the lithium metal battery was charged to 4.25V at a constant current of 3.0mA/ cm2 , and then discharged to 3.0V at a constant current of 3.0mA/ cm2 .
  • Examples 2 to 13 adopt basically the same method as Example 1, except that step (1) is different.
  • the coating thickness, temperature and time of in-situ polymerization reaction can be found in Table 1 and Table 2.
  • Example 2 The steps (1) of Example 2 to Example 13 are as follows respectively.
  • Step (1) Mix 10g of fluorinated monomer, 0.540g of lithium salt and 4.840g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.540g of lithium salt and 4.840g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.955g of lithium salt and 4.425g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.4397g of lithium salt and 4.940g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.5795g of lithium salt and 4.800g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.540g of lithium salt and 4.840g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 18g of fluorinated monomer, 0.201g of lithium salt and 1.799g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 6g of fluorinated monomer, 0.904g of lithium salt and 8.096g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.955g of lithium salt and 4.425g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Comparative Examples 1-11 refer to the preparation method of Example 1, and see Table 1 and Table 2 for differences.
  • Step (1) Mix 20g of fluorinated monomer, 0.041g of lithium salt and 0.367g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 3g of fluorinated monomer, 1.206g of lithium salt and 10.794g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Step (1) Mix 10g of fluorinated monomer, 0.955g of lithium salt and 4.425g of electrolyte solvent at 25°C, and stir evenly at room temperature to obtain a monomer-electrolyte mixture, see table 1 fluorinated monomer.
  • Comparative Example 1 and Comparative Example 2 adopt basically the same method as Example 1. The difference lies in the mass content of the electrolyte in the monomer-electrolyte mixture. See Tables 1 and 2.
  • Comparative Example 3 and Comparative Example 4 adopt basically the same method as Example 1 and Example 1 respectively. The difference is that the concentration of lithium salt in the electrolyte in step (1) is different. See Tables 1 and 2.
  • Comparative Examples 5 and 6 adopted basically the same method as Example 1 and Example 1 respectively. The difference lies in the coating thickness. See Tables 1 and 2.
  • Comparative Example 8 adopts basically the same method as Example 1. The difference is that the structure of monomer compound II is different (the side chain is not substituted by fluorine). See Table 1 and Table 2.
  • Comparative Example 9 A polymer solution with a molecular weight of 1000 kDa was sprayed onto the surface of a pure lithium sheet and dried to obtain a coated polymer layer, which can be seen in Tables 1 and 2.
  • the polymer solution was prepared by dissolving 18 g of polymer in 50 mL of solvent.
  • the polymer was PVdF-HFP (polyvinylidene fluoride-hexafluoropropylene) copolymer, the weight average molecular weight was 500 kDa, and the solvent was tetrahydrofuran (THF). ).
  • Comparative Example 10 a pure lithium sheet was used as the negative electrode sheet, that is, there was no polymer layer.
  • LiFSI lithium bisfluorosulfonimide
  • DME ethylene glycol dimethyl ether
  • step (2) Add 0.48g lithium powder to the uniform solution obtained in step (1), stir quickly and apply it on the glass plate, and let it stand for 2 hours at 30°C to react to obtain a transparent polymer layer film. Thickness 15 ⁇ m.
  • FT-IR Fourier transform infrared spectroscopy
  • Molecular weight test Dissolve the polymer sample in NMP and test the molecular weight through gel permeation chromatography (GPC). The weight average molecular weight, number average molecular weight and molecular weight polydispersity coefficient PDI can be obtained.
  • Polymer layer thickness test Use a laser thickness gauge to measure the thickness of the polymer coating.
  • Viscosity test Use a viscometer to test the viscosity of the polymer solution.
  • the preparation method for polymer dissolution is as follows. Dissolve 5g of polymer in 30mL of NMP. The test temperature is 25°C.
  • the content of fluorine element in the polymer layer can be detected based on X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the test temperature is 25°C. Cut the lithium metal sheet containing the polymer layer into 30 mm ⁇ 30 mm square samples, with three parallel samples in each group, and weigh the mass of each sample. Then, the sample was soaked in 1 mol/L LiFSI DME electrolyte for 2 hours to swell. After swelling, gently wipe the remaining electrolyte on the surface with filter paper, and then weigh the mass of the sample after swelling.
  • the swelling rate of the polymer layer is the mass increase of the sample after swelling as a percentage of the mass of the original sample.
  • d is the membrane thickness, measured with a micrometer
  • A is the area of the membrane
  • R is the impedance of the membrane
  • the test frequency is 10 -6 ⁇ 10 -1 Hz
  • voltage amplitude is 5mV
  • the intersection point of the graph and the horizontal axis is the impedance R of the polymer film.
  • Elastic modulus The test temperature is 25°C. Cut the polymer layer film into long strips with a length L 0 of 150 mm and a width of 20 mm. The elastic modulus of the polymer layer film is measured by a universal testing machine. The stretching distance is 100 mm and the stretching speed is 50 mm/min. The polymer layer film The maximum value of the tensile force is the elastic modulus.
  • the test temperature is 25°C.
  • the elastic deformation of the film can be calculated as (LL 0 )/L 0 ⁇ 100%.
  • the thickness of the polymer layer on the lithium metal surface is controlled to be about 5 ⁇ m, and a range of 50 ⁇ 100 mm is used as a peeling test sample.
  • a sharp blade sharp angle of 15° to 30°
  • 10 ⁇ 10 1mm ⁇ 1mm small grids on the surface of the protective layer sample Each scratch should be as deep as the bottom layer of the protective layer; use a brush to remove the fragments in the test area. Brush clean; use tape with an adhesion of 350g/cm 2 to 400g/cm 2 (3M No. 600 tape or equivalent) to firmly adhere to the small grid to be tested, and wipe the tape vigorously with an eraser to increase the distance between the tape and the quilt.
  • the area is greater than 65%, which is grade 0B; the area is 35%-65%, which is grade 1B; the area is 15%.
  • %-35% it is grade 2B; the area is 5%-15%, it is grade 3B; the area is less than or equal to 5%, it is grade 4B; the edge of the cut is completely smooth, and there is no peeling on the edge of the grid, it is grade 5B.
  • a differential scanning calorimeter test is performed to characterize the glass transition temperature (Tg) of the polymer material.
  • Tg glass transition temperature
  • the DSC test temperature range is 35 ⁇ 800°C, the heating rate is 5°C/min, and the argon atmosphere is used.
  • volume expansion rate of pole piece The test temperature is 25°C. The thickness of the fresh lithium sheet is d1. After the battery has been cycled for 50 cycles to the fully discharged state, the battery is disassembled and the thickness of the lithium sheet is measured with an optical microscope as d2. The expansion rate of the pole piece is (d2-d1)/d1 ⁇ 100%.
  • Cycle performance test The test temperature is 25°C.
  • the lithium metal battery is first charged to 4.25V at a certain constant current, and then discharged to 3.0V to obtain the first-week discharge specific capacity (Cd1). Repeat charging and discharging until 50 weeks.
  • the discharge specific capacity of the lithium metal battery after n cycles is recorded as Cdn.
  • Capacity retention rate discharge specific capacity after n cycles (Cdn)/discharge specific capacity in the first cycle (Cd1) ⁇ 100%.
  • For battery charging current density please refer to Table 3.
  • test results of the polymer molecular weight in the polymer layer, the mass proportion of fluorine element in the polymer, and the thickness of the polymer layer can be seen in Table 2.
  • Test results of the swelling rate, ionic conductivity, elastic modulus and elastic deformation of the polymer layer, as well as the battery charging current density and capacity after 50 cycles of the lithium-ion battery prepared using the negative electrode sheet containing the polymer layer of the present application The retention rate, lithium dendrites, electrode piece volume expansion rate and peeling degree tests can be found in Table 3.
  • Tg -10°C.
  • Comparing Example 1 and Comparative Example 7 shows that the EO chain segment is beneficial to improving the flexibility and elasticity of the polymer layer. After the lithium metal battery is cycled multiple times, the volume expansion of the lithium anode is significantly suppressed, which is beneficial to the battery maintaining good capacity. Retention rate.
  • Example 4 Comparing Example 1 and Example 4, it can be seen that when the fluorine-substituted aliphatic group is connected to the polymer main chain through an amide group (A is NH in Example 4), the polymer protective layer can improve the ionic conductivity of the polymer layer. , elastic modulus, improves the battery charging current density, capacity retention rate and volume expansion performance of secondary batteries after 50 cycles, and significantly inhibits lithium dendrites.
  • Example 6 Comparing Example 1 and Example 6, it can be seen that when the fluorine-substituted aliphatic group is connected to the polymer main chain through a phosphate group (A in Example 6 is O, and the side of Rf close to the EO segment is ), the polymer protective layer can improve the ionic conductivity of the polymer layer, improve the battery charging current density, capacity retention rate and volume expansion performance of the secondary battery after 50 cycles, and significantly inhibit lithium dendrites.
  • a in Example 6 is O, and the side of Rf close to the EO segment is
  • Comparing Examples 7-8 and Comparative Examples 1-2 it can be seen that controlling the electrolyte content in the polymer layer can regulate the swelling rate and mechanical properties of the polymer layer.
  • Comparative Example 1 although the high electrolyte content is beneficial to the improvement of ionic conductivity, the rigidity of the diaphragm is low, which is not conducive to high current charging and discharging above 3mA/ cm2 , serious dendrites, large volume expansion, and rapid capacity attenuation.
  • Comparative Example 2 the ionic conductivity decreased, which was not conducive to high-current charging and discharging above 3 mA/cm 2 , dendrites were serious, the volume expanded greatly, and the capacity declined rapidly.
  • the EO segment has obvious advantages over other types of polymer segments in terms of ionic conductivity, cycle performance, reduction of lithium dendrites, and control of pole piece expansion.
  • the diaphragm can obtain higher conductivity and mechanical strength, which is beneficial to the application of the protective layer in large-scale applications.
  • Lithium metal battery that performs charge and discharge cycles at current density.

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Abstract

La présente invention concerne un matériau de lithium modifié par un polymère, comprenant un métal contenant du lithium et un polymère Poly chimiquement lié à la surface du lithium dans le métal contenant du lithium, Poly comprenant une structure représentée dans la formule I ; à chaque fois que chaque groupe apparaît, Rf est indépendamment un groupe aliphatique substitué par fluor, X est indépendamment H ou un groupe attracteur d'électrons, A est indépendamment O, S ou NR11, R11 est H ou alkyle en C1-3, Z2 est indépendamment une liaison, carbonyle, -(O=)P(-O-)2, -S(=O)2-, -C(=O)-NH- ou LC-Z0, Lc est alkylène en C1-3 , et Z0 est un ligand conjugué; n ≥ 10 ; m ≤ 10 ; et au moins un groupe cyano dans Poly forme une liaison chimique avec le lithium dans le métal contenant du lithium.
PCT/CN2022/110781 2022-08-08 2022-08-08 Matériau de lithium modifié par polymère, feuille d'électrode négative, batterie secondaire, dispositif électrique, procédé et application WO2024031220A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110915049A (zh) * 2017-04-12 2020-03-24 纳米技术仪器公司 用于锂金属二次电池的保护锂阳极的聚合物层及制造方法
CN112421046A (zh) * 2020-11-30 2021-02-26 南开大学 用于锂金属二次电池的单离子导电聚合物复合材料的制备方法
US20210087317A1 (en) * 2018-07-27 2021-03-25 Lg Chem, Ltd. Electrode protective layer polymer and secondary battery to which same is applied
CN113912898A (zh) * 2021-12-16 2022-01-11 中山大学 一种用于超高倍率大容量锂金属负极的全有机多孔保护膜及其制备方法和应用

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110915049A (zh) * 2017-04-12 2020-03-24 纳米技术仪器公司 用于锂金属二次电池的保护锂阳极的聚合物层及制造方法
US20210087317A1 (en) * 2018-07-27 2021-03-25 Lg Chem, Ltd. Electrode protective layer polymer and secondary battery to which same is applied
CN112421046A (zh) * 2020-11-30 2021-02-26 南开大学 用于锂金属二次电池的单离子导电聚合物复合材料的制备方法
CN113912898A (zh) * 2021-12-16 2022-01-11 中山大学 一种用于超高倍率大容量锂金属负极的全有机多孔保护膜及其制备方法和应用

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