阅读说明：本技术 一种带有保护层的负极及其制备方法、二次电池 (Negative electrode with protective layer, preparation method of negative electrode and secondary battery ) 是由 张校刚 黄康生 徐呈旸 吴朗源 俞家辉 于 2021-03-09 设计创作，主要内容包括：本发明涉及电池技术领域,尤其涉及一种带有保护层的负极及其制备方法、二次电池。本发明提供的制备方法,包括以下步骤：将碱金属盐和阴离子受体化合物混合,得到电解质溶液；将所述电解质溶液包覆在电池负极的工作面后,干燥,得到带有保护层的负极；所述阴离子受体化合物包括(C-6H-3F)O-2B(C-6H-3F-2)、(C-6F-4)O-2B(C-6F-5)、三(五氟苯基)硼烷、[(CF-3)CHO]-3B、(C-6F-5O)-3B、氟代碳酸乙烯酯、碳酸甲乙酯、碳酸二甲酯、碳酸二乙酯和三(三甲基硅烷)硼酸酯中的一种或几种。本发明提供的制备方法制备得到的带有保护层的负极作为二次电池的负极具有较好的循环稳定性。(The invention relates to the technical field of batteries, in particular to a negative electrode with a protective layer, a preparation method of the negative electrode and a secondary battery. The preparation method provided by the invention comprises the following steps: mixing an alkali metal salt and an anion receptor compound to obtain an electrolyte solution; coating the working surface of the battery cathode with the electrolyte solution, and drying to obtain a cathode with a protective layer; the anion receptor compound comprises (C) 6 H 3 F)O 2 B(C 6 H 3 F 2 )、(C 6 F 4 )O 2 B(C 6 F 5 ) Tris (pentafluorophenyl) borane, [ (CF) 3 )CHO] 3 B、(C 6 F 5 O) 3 B. One or more of fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and tris (trimethylsilane) borate. The cathode with the protective layer prepared by the preparation method provided by the invention has better cycle stability when being used as a cathode of a secondary battery.)

1. A preparation method of a negative electrode with a protective layer is characterized by comprising the following steps:

mixing an alkali metal salt and an anion receptor compound to obtain an electrolyte solution;

coating the working surface of the battery cathode with the electrolyte solution, and drying to obtain a cathode with a protective layer;

the anion receptor compound comprises (C)₆H₃F)O₂B(C₆H₃F₂)、(C₆F₄)O₂B(C₆F₅) Tris (pentafluorophenyl) borane, [ (CF)₃)CHO]₃B、(C₆F₅O)₃B. One or more of fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and tris (trimethylsilane) borate.

2. The method of claim 1, wherein the alkali metal salt comprises LiF, LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of them.

3. The method according to claim 1 or 2, wherein the concentration of the electrolyte solution is 0.1 to 10 mol/L.

4. The method of claim 1, wherein the battery negative electrode comprises an alkali metal negative electrode or a non-alkali metal negative electrode;

the negative electrode material of the alkali metal negative electrode is lithium, potassium, sodium, a lithium alloy, a potassium alloy or a sodium alloy;

the negative electrode material of the non-alkali metal negative electrode is graphite, Si, silicon oxide, silicon alloy, tin alloy, lithium titanate or metal oxide;

the metal in the metal oxide is Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ge or Zn.

5. The negative electrode with the protective layer prepared by the preparation method of any one of claims 1 to 4.

6. A secondary battery is characterized by comprising a positive electrode, a diaphragm, an electrolyte and a negative electrode with a protective layer;

the negative electrode with a protective layer is the negative electrode with a protective layer according to claim 5.

7. The secondary battery according to claim 6, wherein the positive electrode active material of the positive electrode is Li_wNi_xCo_yMn_zA_(1-x-y-z)O₂、LiCo_xA_(1-x)O₂、LiFe_xA_(1-x)PO₄、Na_wNi_xCo_yMn_zA_(1-x-y-z)O₂、NaCo_xA_(1-x)O₂、NaFe_xA_(1-x)PO₄、K_wNi_xCo_yMn_zA_(1-x-y-z)O₂、KCo_xA_(1-x)O₂And KFe_xA_(1-x)PO₄One or more of the above;

wherein A is Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, and w is more than or equal to 0 and less than or equal to 2.

8. The secondary battery of claim 6, wherein the electrolyte comprises a solvent and a solute;

the concentration of the electrolyte is 0.1-10 mol/L.

9. The secondary battery according to claim 8, wherein the solvent is one or more of dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile, acrylonitrile, dimethyl sulfoxide, trimethylolpropane, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, a fluorine-containing solvent, ethyl acetate, propyl acetate, ethylene glycol dimethyl ether, tetrahydrofuran, butyl acrylate, dibutyl sulfate, ethyl propionate, propyl propionate, and butyl propionate.

10. The secondary battery of claim 8, wherein the solute is LiF, LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of them.

Technical Field

The invention relates to the technical field of batteries, in particular to a negative electrode with a protective layer, a preparation method of the negative electrode and a secondary battery.

Background

With the continuous development of economy and the continuous progress of science and technology, people have increasingly increased demands for electric vehicles, portable electronic devices, and the like. Accordingly, the electrical performance of the battery system is more and more demanding. However, the energy density of the conventional secondary alkali ion battery is low and the phenomenon of poor stability is easy to occur in the process of charge and discharge cycle due to the battery cathode material. Therefore, it is important for the further development of secondary batteries to find a method which is simple and easy to implement and can improve the cycle stability of the negative electrode.

Disclosure of Invention

The invention aims to provide a negative electrode with a protective layer, a preparation method thereof and a secondary battery.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a cathode with a protective layer, which comprises the following steps:

mixing an alkali metal salt and an anion receptor compound to obtain an electrolyte solution;

coating the working surface of the battery cathode with the electrolyte solution, and drying to obtain a cathode with a protective layer;

the anion receptor compound comprises (C)₆H₃F)O₂B(C₆H₃F₂)、(C₆F₄)O₂B(C₆F₅) Tris (pentafluorophenyl) borane (TPFPB), [ (CF)₃)CHO]₃B、(C₆F₅O)₃B. Fluoroethylene carbonate, methylethyl carbonate, dimethyl carbonate, diethyl carbonateAnd tris (trimethylsilane) borate (TMSB).

Preferably, the alkali metal salt comprises LiF, LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of them.

Preferably, the concentration of the electrolyte solution is 0.1-10 mol/L.

Preferably, the battery negative electrode comprises an alkali metal negative electrode or a non-alkali metal negative electrode;

the negative electrode material of the alkali metal negative electrode is lithium, potassium, sodium, a lithium alloy, a potassium alloy or a sodium alloy;

the negative electrode material of the non-alkali metal negative electrode is graphite, Si, silicon oxide, silicon alloy, tin alloy lithium titanate or metal oxide;

the metal in the metal oxide is Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ge or Zn.

The invention also provides the cathode with the protective layer prepared by the preparation method in the technical scheme.

The invention also provides a secondary battery, which comprises a positive electrode, a diaphragm, electrolyte and a negative electrode with a protective layer;

the negative electrode with the protective layer is the negative electrode with the protective layer in the technical scheme.

Preferably, the positive electrode active material of the positive electrode is Li_wNi_xCo_yMn_zA_(1-x-y-z)O₂、LiCo_xA_(1-x)O₂、LiFe_xA_(1-x)PO₄、Na_wNi_xCo_yMn_zA_(1-x-y-z)O₂、NaCo_xA_(1-x)O₂、NaFe_xA_(1-x)PO₄、K_wNi_xCo_yMn_zA_(1-x-y-z)O₂、KCo_xA_(1-x)O₂And KFe_xA_(1-x)PO₄One or more of the above;

wherein A is Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, and w is more than or equal to 0 and less than or equal to 2.

Preferably, the electrolyte comprises a solvent and a solute;

the concentration of the electrolyte is 0.1-10 mol/L.

Preferably, the solvent is one or more of dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, acetonitrile, acrylonitrile, dimethyl sulfoxide, trimethylolpropane, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, a fluorine-containing solvent, ethyl acetate, propyl acetate, ethylene glycol dimethyl ether, tetrahydrofuran, butyl acrylate, dibutyl sulfate, ethyl propionate, propyl propionate and butyl propionate.

Preferably, the solute is LiF or LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of them.

The present invention providesA preparation method of a negative electrode with a protective layer is provided, which comprises the following steps: mixing an alkali metal salt and an anion receptor compound to obtain an electrolyte solution; coating the working surface of the battery cathode with the electrolyte solution, and drying to obtain a cathode with a protective layer; the anion receptor compound comprises (C)₆H₃F)O₂B(C₆H₃F₂)、(C₆F₄)O₂B(C₆F₅) Tris (pentafluorophenyl) borane, [ (CF)₃)CHO]₃B、(C₆F₅O)₃B. One or more of fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and tris (trimethylsilane) borate. The anion receptor compound in the electrolyte solution can gather more anions, so that alkali metal is better protected; meanwhile, the anion receptor compound has specific adsorption, so that the alkali metal salt can be better dissolved in the electrolyte solution; after obtaining the electrolyte solution, coating the electrolyte solution on the working surface of the battery cathode, drying to form a protective layer, and when the battery cathode is an alkali metal cathode, generating Li-rich Li in the protective layer in the process of charging and discharging₂O、LiF、B、Li₂CO₃、LiPF_X、Li_xPO₂F₂、POF₃、FOF(OH)₂An inorganic-like layer and a carbonate-based organic layer. The protective layer can effectively inhibit the growth of lithium dendrites and has high ionic conductivity. When the battery cathode is a non-alkali metal cathode, the protective layer can gather more anions to spontaneously form a stable SEI layer, so that the reaction between the non-alkali metal cathode and an electrolyte can be reduced, the side reaction, the electrolyte drying and the like can be prevented, and the cycle stability of the alkali metal cathode can be improved.

Drawings

Fig. 1 is an SEM image of the negative electrode with the protective layer prepared in example 1;

fig. 2 is a cycle curve of the lithium metal batteries prepared in example 1 and comparative example 1.

Detailed Description

The invention provides a preparation method of a cathode with a protective layer, which comprises the following steps:

mixing an alkali metal salt and an anion receptor compound to obtain an electrolyte solution;

coating the working surface of the battery cathode with the electrolyte solution, and drying to obtain a cathode with a protective layer;

the anion receptor compound comprises (C)₆H₃F)O₂B(C₆H₃F₂)、(C₆F₄)O₂B(C₆F₅)、TPFPB、[(CF₃)CHO]₃B、(C₆F₅O)₃B. One or more of fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and TMSB.

In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.

The present invention mixes an alkali metal salt and an anion receptor compound to obtain an electrolyte solution. In the present invention, the alkali metal salt includes LiF, LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of the above; when the alkali metal salt is more than two of the above specific choices, the specific proportion of the specific substances is not limited in any way, and the specific substances can be mixed according to any proportion.

In bookIn the invention, the anion receptor compound comprises (C)₆H₃F)O₂B(C₆H₃F₂)、(C₆F₄)O₂B(C₆F₅)、TPFPB、[(CF₃)CHO]₃B、(C₆F₅O)₃B. One or more of fluoroethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate and TMSB, and when the anion receptor compound is two or more of the above specific substances, the ratio of the specific substances is not particularly limited, and the specific substances may be mixed in any ratio.

In the invention, the anion receptor has specific adsorption and can provide better dissolution for alkali metal salt, so that a negative electrode protection substance (namely alkali metal salt) can be more uniformly coated on the surface of a negative electrode working surface, and further better protection is provided for a battery negative electrode.

In the invention, the concentration of the electrolyte solution is preferably 0.1-10 mol/L, more preferably 2-8 mol/L, and most preferably 4-6 mol/L.

The present invention is not limited to any particular mixing, and the procedure described by those skilled in the art is employed to ensure that the alkali metal salt is sufficiently dissolved in the anion receptor compound to form a homogeneous electrolyte solution.

After the electrolyte solution is obtained, the working surface of the battery cathode is coated with the electrolyte solution and then dried to obtain the cathode with the protective layer.

In the present invention, the battery negative electrode preferably includes an alkali metal negative electrode or a non-alkali metal negative electrode; the negative electrode material of the alkali metal negative electrode is lithium, potassium, sodium, a lithium alloy, a potassium alloy or a sodium alloy; the present invention is not limited to any particular kind of the lithium alloy, potassium alloy and sodium alloy, and any of the lithium alloy, potassium alloy and sodium alloy that can be used for an alkali metal electrode, which are well known to those skilled in the art, may be used. The negative electrode material of the non-alkali metal negative electrode is preferably graphite, Si, silicon oxide, silicon alloy, tin alloy lithium titanate or metal oxide; the metal in the metal oxide is preferably Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ge or Zn; the present invention is not limited to any particular kind of silicon alloy and tin alloy, and silicon alloys and tin alloys that can be used for non-alkali metal negative electrodes, which are well known to those skilled in the art, may be used.

In the invention, the coating mode is preferably dripping, coating or soaking; the present invention does not have any particular limitation on the specific processes of the dropping, coating and soaking, and processes well known to those skilled in the art can be adopted.

The coating amount of the electrolyte solution is not limited in any way, and the coating amount is well known to those skilled in the art to be uniformly coated on the working surface of the battery cathode.

In the present invention, the drying is preferably carried out in an oxygen-free environment, more preferably in a glove box; the drying conditions in the present invention are not particularly limited, and may be drying conditions known to those skilled in the art.

The invention also provides the cathode with the protective layer prepared by the preparation method in the technical scheme. In the present invention, the protective layer in the negative electrode with the protective layer is preferably an alkali metal salt in the electrolyte solution in the above technical solution, i.e. LiF, LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of them.

The invention also provides a secondary battery, which comprises a positive electrode, a diaphragm, electrolyte and a negative electrode with a protective layer;

the negative electrode with the protective layer is the negative electrode with the protective layer in the technical scheme.

In the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material; the positive electrode current collector is preferably an aluminum sheet, and the positive electrode active material is Li_wNi_xCo_yMn_zA_(1-x-y-z)O₂、LiCo_xA_(1-x)O₂、LiFe_xA_(1-x)PO₄、Na_wNi_xCo_yMn_zA_(1-x-y-z)O₂、NaCo_xA_(1-x)O₂、NaFe_xA_(1-x)PO₄、K_wNi_xCo_yMn_zA_(1-x-y-z)O₂、KCo_xA_(1-x)O₂And KFe_xA_(1-x)PO₄One or more of the above; wherein A is independently preferably Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe; the independent value range of x is preferably 0-1, the value range of y is preferably 0-1, the value range of z is preferably 0-1, and the value range of w is preferably 0-2.

The amount of the positive active material in the positive electrode and the preparation process of the positive electrode are not limited in any way, and the amount and the preparation process known to those skilled in the art can be adopted.

The separator of the present invention is not particularly limited, and those known to those skilled in the art can be used.

In the present invention, the electrolyte preferably includes a solvent and a solute; the solvent preferably includes one or more of dimethyl ether (DME), diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, Acetonitrile (ACN), Acrylonitrile (AN), dimethyl sulfoxide (DMSO), Trimethylolpropane (TMP), Ethylene Carbonate (EC), Propylene Carbonate (PC), Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), a fluorine-containing solvent, Ethyl Acetate (EA), propyl acetate, ethylene glycol dimethyl ether (DME), Tetrahydrofuran (THF), Butyl Acrylate (BA), butylene sulfate, ethyl propionate, propyl propionate, and butyl propionate; said containsThe fluorine solvent is preferably one or more of fluoroethylene carbonate (FEC), 4-trifluoro methyl propylene carbonate (TFPC), fluoro methyl ethyl carbonate (FEMC), bis- (p-chlorophenyl) trifluoromethyl methanol (FDMC) and 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether; when the solvent is more than two of the above specific choices, the invention does not have any special limitation on the proportion of the specific substances, and the specific substances are mixed according to any proportion. The solute is preferably LiF or LiNO₃、KF、KNO₃、NaNO₃、LiPF₂、LiPF₆、LiClO₄、KClO₄、KPF₆、KFSi、NaF、NaNO₃、NaPF₆、NaFSi、LiBF₄、LiBOB、LiDFOB、LiAsF₆、LiSbF₆、LiCF₃SO₃、LiN(SO₂CF₃)₂、LiN(SO₂C₂F₅)₂、LiN(SO₂CF₃)₂、LiN(SO₂CF₃)₃、LiPF₃(C₃F₇)₃、LiB(CF₃)₄And LiBF₃(C₂F₅) One or more of the above; when the solute is more than two of the above specific choices, the invention does not have any special limitation on the proportion of the specific substances, and the specific substances are mixed according to any proportion.

In the invention, the concentration of the solute in the electrolyte is preferably 0.1-10 mol/L, more preferably 2-8 mol/L, and most preferably 4-6 mol/L.

The present invention does not have any particular limitation on the process for preparing the secondary battery, and may be performed by a process known to those skilled in the art.

The negative electrode with a protective layer, the method for producing the same, and the secondary battery according to the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited to these examples.

Example 1

Mixing 2g LiF and 50mL of tris (trimethylsilane) borate to obtain an electrolyte solution;

dropwise adding 0.1mL of the electrolyte solution on the working surface of a metal lithium sheet, and drying in a glove box to obtain a cathode with a protective layer;

taking an aluminum sheet as a positive electrode current collector, a ternary material NCM811 as a positive electrode active substance, the negative electrode with the protective layer as a negative electrode, and mixing the positive electrode, a diaphragm and an electrolyte (the concentration is 1.5mol/L, the solvent is a mixture of EC and DMC in a volume ratio of 1: 1, and the solute is LiPF₆) And mounting the negative electrode with a protective layer to prepare the lithium metal battery;

the protective layer in the cathode with the protective layer is subjected to SEM test, the test result is shown in figure 1, and as can be seen from figure 1, the surface of Li metal is covered by a layer of compact crystals, namely the protective layer, and the protective layer can reduce dendritic crystal growth, so that the metal cathode is effectively protected.

Example 2

Mixing 2g NaF and 50mL fluoroethylene carbonate to obtain an electrolyte solution;

dropwise adding 0.1mL of the electrolyte solution on the working surface of the metal sodium sheet, and drying in a glove box to obtain a cathode with a protective layer;

taking an aluminum sheet as a positive electrode current collector, a ternary material NCM811 as a positive electrode active substance, the negative electrode with the protective layer as a negative electrode, and mixing the positive electrode, a diaphragm and an electrolyte (the concentration is 1.5mol/L, the solvent is a mixture of EC and DMC in a volume ratio of 1: 1, and the solute is NaPF₆) And mounting the cathode with a protective layer to prepare the sodium metal battery.

Example 3

2g KNO₃Mixing 50mL of dimethyl carbonate and 50mL of diethyl carbonate to obtain an electrolyte solution;

dropwise adding 0.1mL of the electrolyte solution on the working surface of a potassium metal sheet, and drying in a glove box to obtain a cathode with a protective layer;

taking an aluminum sheet as a positive electrode current collector, a ternary material NCM811 as a positive electrode active substance, the negative electrode with the protective layer as a negative electrode, and mixing the positive electrode, a diaphragm and an electrolyte (the concentration is 1.5mol/L, the solvent is a mixture of EC and DMC in a volume ratio of 1: 1, and the solute is KPF₆) And a negative electrode with a protective layerAnd (5) mounting and preparing to obtain the potassium metal battery.

Example 4

Mixing 1g LiF and 50mL of tris (trimethylsilane) borate to obtain an electrolyte solution;

dropwise adding 0.1mL of the electrolyte solution on the working surface of the graphite electrode, and drying in a glove box to obtain a cathode with a protective layer;

taking an aluminum sheet as a positive electrode current collector, a ternary material NCM811 as a positive electrode active substance, the negative electrode with the protective layer as a negative electrode, and mixing the positive electrode, a diaphragm and an electrolyte (the concentration is 1.5mol/L, the solvent is a mixture of EC and DMC in a volume ratio of 1: 1, and the solute is LiPF₆) And mounting the cathode with a protective layer to prepare the lithium ion battery;

comparative example 1

Taking an aluminum sheet as a positive electrode current collector, taking a ternary material NCM811 as a positive electrode active substance, taking a lithium sheet as a negative electrode, and taking a positive electrode, a diaphragm and an electrolyte (the concentration is 1.5mol/L, the solvent is a mixture of EC and DMC in a volume ratio of 1: 1, and the solute is LiPF₆) And mounting a lithium sheet to prepare the lithium metal battery.

Test example

The lithium metal batteries prepared in example 1, example 4 and comparative example 1 were subjected to constant current charge and discharge cycle test at a current density of 1mA cm^-2As shown in fig. 2, it can be seen from fig. 2 that the cell after 50 cycles of the button full cell cycle shows higher cell capacity and higher capacity retention rate under the same current density. The protective layer effectively improves the specific capacity and the cycling stability of the battery;

the secondary batteries prepared in examples 1 to 4 were subjected to constant current charge-discharge cycle test at a current density of 1mA cm^-2The capacity retention is shown in table 1:

TABLE 1 Capacity conservation Rate of Secondary batteries prepared in examples 1 to 4

As is apparent from table 1, the electrode with a protective layer according to the present invention can improve charge and discharge cycle performance of a secondary battery.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.