Battery capable of supplementing lithium or sodium in situ

Abstract

The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a battery capable of supplementing lithium or sodium in situ, which comprises a positive plate, a negative plate and an electrolyte, and is characterized in that the electrolyte contains a component A, and a positive electrode and / or a negative electrode contains a component B; the structural general formula of the component A is X-Y, and X is lithium fluorosulfonate, sodium fluorosulfonate, lithium difluorophosphate or sodium difluorophosphate; y is boron trifluoride or phosphorus pentafluoride; the component B is at least one of lithium oxalate, sodium oxalate, lithium fluoride and sodium fluoride. Compared with the prior art, the component A and the component B are simultaneously added into the battery disclosed by the invention, so that the battery shows more excellent cycle performance and high-temperature performance. The combination mode has better performance compared with the mode that the component B is independently used in the electrode material or the component A is independently used in the electrolyte.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage, and particularly relates to a battery capable of in-situ lithium or sodium supplementation. Background Art

[0002] At present, for commercial lithium (sodium) ion batteries, due to irreversible side reactions occurring during the formation stage and subsequent cycling of the electrode materials and interfaces, the loss of lithium / sodium ions and the attenuation of battery capacity are caused. Therefore, the industry attempts to solve this problem by means of lithium (sodium) supplementation.

[0003] Currently, the relatively mature methods of lithium (sodium) supplementation include:

[0004] 1) Adding a lithium (sodium) source (such as lithium powder, sodium powder, etc.) to the negative electrode;

[0005] 2) Adding a lithium (sodium) source (such as lithium ferrate, etc.) to the positive electrode;

[0006] 3) Adding a lithium (sodium) source (such as lithium trifluoromethanesulfonate, etc.) to the electrolyte.

[0007] The lithium supplementation process through the negative electrode has high process requirements, high costs, and poor safety, which is not conducive to large-scale production. After lithium / sodium supplementation through the positive electrode, by-products remain in the battery, reducing the energy density of the battery, easily creating pores in the positive electrode, and reducing the cycle performance of the battery. Adding lithium trifluoromethanesulfonate to the electrolyte, through the electrochemical oxidation-reduction process, the trifluoromethanesulfonate group is converted into a gas. The lithium supplement is cheap and easily available, and no by-products remain in the battery system. However, the solubility of lithium trifluoromethanesulfonate in the electrolyte is relatively poor, and the lithium supplementation effect is relatively limited.

[0008] In view of this, the present invention aims to provide a battery capable of in-situ lithium or sodium supplementation, which can play a good role in lithium supplementation and extend the service life of the battery through a clever formulation design. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, a battery capable of in-situ lithium or sodium supplementation is provided, which can play a good role in lithium supplementation and extend the service life of the battery through a clever formulation design.

[0010] To solve the above problems, the technical solution of the present invention is as follows:

[0011] A battery capable of in-situ lithium or sodium supplementation, comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte, wherein the electrolyte contains component A, and the positive electrode and / or the negative electrode contains component B;

[0012] The structural general formula of component A is X-Y, wherein X is lithium fluorosulfonate, sodium fluorosulfonate, lithium difluorophosphate, or sodium difluorophosphate; Y is boron trifluoride or phosphorus pentafluoride;

[0013] Component B is at least one of lithium oxalate, sodium oxalate, lithium fluoride, and sodium fluoride.

[0014] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the mass percentage content of Component A in the electrolyte is 0.1% to 40%.

[0015] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the mass percentage content of Component A in the electrolyte is 0.3% to 30%.

[0016] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the mass percentage content of Component B in the positive electrode and / or the negative electrode is 0.1% to 20%.

[0017] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the mass percentage content of Component B in the positive electrode and / or the negative electrode is 0.2% to 15%.

[0018] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the electrolyte further includes a conductive lithium sodium salt or a conductive sodium salt, a non-aqueous organic solvent, and an additive.

[0019] As an improvement to the battery of the present invention capable of in-situ lithium or sodium supplementation, the conductive lithium salt is at least one of LiBF4, LiPF6, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiN(SO2CF3)2, and LiN(SO2F)2; the conductive sodium salt is at least one of NaBF4, NaPF6, NaAsF6, NaClO4, NaSO3CF3, NaB(C2O4)2, NaBF2C2O4, NaN(SO2CF3)2, and NaN(SO2F)2;

[0020] The non-aqueous organic solvent is at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, and butyl propionate.

[0021] The additive is at least one of vinylene carbonate, ethylene vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, ethylene sulfate, propylene sulfate, ethylene sulfite, propylene sulfite, succinonitrile, adiponitrile, 1,2-cyanoethoxyethane, and hexane trinitrile.

[0022] As an improvement of the battery capable of in-situ lithium or sodium supplementation according to the present invention, the positive electrode sheet and the negative electrode sheet both comprise active materials, conductive agents, current collectors, and binders for binding the active materials and the conductive agents to the current collectors;

[0023] The positive electrode sheet includes a positive electrode active material capable of reversibly inserting / extracting lithium or sodium ions. The positive electrode active material is a composite metal oxide of lithium or sodium, and the metal oxide includes oxides of nickel, cobalt, manganese elements and any proportion combination thereof;

[0024] The negative electrode sheet includes a negative electrode active material capable of accepting or releasing lithium or sodium ions. The negative electrode active material includes lithium or sodium metal, lithium or sodium alloy, crystalline carbon, amorphous carbon, carbon fiber, hard carbon, soft carbon; wherein the crystalline carbon includes natural graphite, graphitized coke, graphitized MCMB, graphitized mesophase pitch carbon fiber; the lithium or sodium alloy includes alloys of lithium or sodium and metals such as aluminum, zinc, silicon, tin, gallium, antimony.

[0025] As an improvement of the battery capable of in-situ lithium or sodium supplementation according to the present invention, the positive electrode active material further includes at least one of chemical elements, and the chemical elements include Mg, Al, Ti, Sn, V, Ge, Ga, B, Zr, Cr, Fe, Sr, and rare earth elements.

[0026] As an improvement of the battery capable of in-situ lithium or sodium supplementation according to the present invention, the positive electrode active material further includes a polyanionic lithium compound LiM x (PO4) y , wherein M is Ni, Co, Mn, Fe, Ti, V, 0 ≤ x ≤ 5, 0 ≤ y ≤ 5.

[0027] Compared with the prior art, by adding lithium oxalate, sodium oxalate, lithium fluoride or sodium fluoride to the positive electrode and / or the negative electrode, the present invention has a certain lithium supplement function, which can slightly improve the cycle performance of the battery. However, lithium oxalate, sodium oxalate, lithium fluoride or sodium fluoride is insoluble in the electrolyte, and it is easy to lose the lithium supplement performance after being passivated on the surface, resulting in limited improvement in performance. Adding lithium / sodium difluorophosphate and lithium / sodium fluorosulfonate complexes to the electrolyte is beneficial to improving the cycle performance and high-temperature storage performance. When components A and B are added to the battery simultaneously, more excellent cycle performance and high-temperature performance are demonstrated. The main reason is that during the formation process and subsequent cycling of the battery, BF3 or PF5 of component A reacts with lithium / sodium oxalate or lithium / sodium fluoride of component B, and the component B that is insoluble in the electrolyte is converted into lithium compounds such as lithium / sodium difluorooxalate borate, lithium / sodium difluorobis(oxalato)phosphate, lithium / sodium tetrafluoroborate, etc. that are soluble in the electrolyte through a chemical reaction method, playing the role of in-situ continuous lithium supplementation. Moreover, the difluorooxalate borate anion or difluorobis(oxalato)phosphate anion formed during this process can be further used to repair the interface film. Therefore, this combination method has more excellent performance than using component B alone in the electrode material or using component A alone in the electrolyte. Detailed Embodiments

[0028] The present invention provides a battery capable of in-situ lithium or sodium supplementation, including a positive electrode sheet, a negative electrode sheet and an electrolyte. The electrolyte contains component A, and the positive electrode and / or the negative electrode contains component B;

[0029] The structural general formula of component A is X-Y, where X is lithium fluorosulfonate, sodium fluorosulfonate, lithium difluorophosphate or sodium difluorophosphate; Y is boron trifluoride or phosphorus pentafluoride;

[0030] Component B is at least one of lithium oxalate, sodium oxalate, lithium fluoride and sodium fluoride.

[0031] The mass percentage content of component A in the electrolyte is 0.1% - 40%, preferably 0.3% - 30%.

[0032] The mass percentage content of component B in the positive electrode and / or the negative electrode is 0.1% - 20%, preferably 0.2% - 15%.

[0033] The electrolyte further includes a conductive lithium salt or a conductive sodium salt, a non-aqueous organic solvent and an additive.

[0034] The conductive lithium salt is at least one of LiBF4, LiPF6, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiN(SO2CF3)2, and LiN(SO2F)2; the conductive sodium salt is at least one of NaBF4, NaPF6, NaAsF6, NaClO4, NaSO3CF3, NaB(C2O4)2, NaBF2C2O4, NaN(SO2CF3)2, and NaN(SO2F)2;

[0035] The non-aqueous organic solvent is at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, and butyl propionate.

[0036] The additive is at least one of vinylene carbonate, ethylene vinyl carbonate, fluoroethylene carbonate, difluoroethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, ethylene sulfate, propylene sulfate, ethylene sulfite, propylene sulfite, succinonitrile, adiponitrile, 1,2-cyanoethoxyethane, and hexane trinitrile.

[0037] Both the positive electrode sheet and the negative electrode sheet include an active material, a conductive agent, a current collector, and a binder (such as a thickener, a dispersant, and an adhesive, etc.) that combines the active material and the conductive agent with the current collector;

[0038] The positive electrode sheet includes a positive electrode active material capable of reversibly intercalating / deintercalating lithium or sodium ions, and the positive electrode active material is a composite metal oxide of lithium or sodium, and the metal oxide includes oxides of nickel, cobalt, manganese elements and any proportion combination thereof;

[0039] The negative electrode sheet includes a negative electrode active material capable of accepting or releasing lithium or sodium ions, and the negative electrode active material includes lithium or sodium metal, lithium or sodium alloy, crystalline carbon, amorphous carbon, carbon fiber, hard carbon, soft carbon; among them, the crystalline carbon includes natural graphite, graphitized coke, graphitized MCMB, graphitized mesophase pitch carbon fiber; the lithium or sodium alloy includes an alloy of lithium or sodium and aluminum, zinc, silicon, tin, gallium, antimony metals.

[0040] The positive electrode active material further includes at least one of chemical elements, and the chemical elements include Mg, Al, Ti, Sn, V, Ge, Ga, B, Zr, Cr, Fe, Sr, and rare earth elements.

[0041] The positive electrode active material further includes a polyanionic lithium compound LiM x (PO4) y , where M is Ni, Co, Mn, Fe, Ti, V, 0≤x≤5, 0≤y≤5.

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application. Although only some substances are listed in the following embodiments, it should be emphasized that all substances listed in the present invention are applicable.

[0043] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0044] In the following embodiments and comparative examples, unless otherwise specified, all raw materials can be prepared and synthesized by conventional methods or obtained commercially.

[0045] Example 1-1

[0046] This embodiment provides a lithium-ion battery capable of in-situ lithium supplementation, and its preparation method includes the following steps:

[0047] (1) Preparation of the electrolyte

[0048] In a glove box under an argon atmosphere (H2O < 1 ppm), prepare the following electrolyte formulation: 12.5% LiPF6, 2% VC, 0.5% PS, 5% LiPO2F2·BF3, EC / DMC / EMC = 40 / 40 / 20 (volume ratio), stir well, and the electrolyte for the lithium secondary battery described in the present invention is obtained (free acid < 15 ppm, moisture < 10 ppm).

[0049] (2) Preparation of the positive electrode sheet

[0050] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 3% in an NMP solution, add lithium cobaltate with a mass percentage of 92%, 2% conductive agent, 2.5% lithium oxalate, and 0.5% dispersant to the above solution and mix well. After coating the mixed slurry on both sides of the aluminum foil, dry and roll it to obtain the positive electrode sheet. Other positive electrode materials such as LiMn2O4, LiPO2F2, LiNi 0.5 Co 0.3 Mn 0.2 、LiNi 0.3 Co 0.3 Mn 0.3 are prepared in the same way.

[0051] (3) Preparation of the negative electrode sheet

[0052] Dissolve an SBR binder with a mass percentage of 4% and a CMC thickener with a mass percentage of 1% in an aqueous solution. Add graphite with a mass percentage of 95% to the above solution and mix evenly. After coating the mixed slurry on both sides of the copper foil, dry it and roll it to obtain a negative electrode sheet.

[0053] (4) Fabrication of lithium-ion battery

[0054] Make a square battery cell by winding the above-prepared positive electrode sheet, negative electrode sheet and separator, package it with a polymer, pour the above-prepared electrolyte, and fabricate a lithium-ion battery through processes such as formation.

[0055] (5) Battery performance test

[0056] Cycling test conditions: After the battery undergoes a high-temperature formation process, perform charge-discharge cycling tests on the battery at a charge-discharge rate of 1 / 1C; High-temperature storage test conditions: First, charge and discharge the formed battery once at 1C at room temperature, then fully charge the battery at 1C and perform high-temperature storage. After the battery has completely cooled down, discharge the removed battery at 1C for testing.

[0057] For Examples 1-2 to 1-11 and Comparative Examples 2-1 to 2-3, except for the parameters in the following table, other parameters and preparation methods are the same as those in Example 1-1.

[0058] Table 1 Examples 1-2 to 1-11 and Comparative Examples 2-1 to 2-3

[0059]

[0060] For Comparative Examples 3-1 to 3-7, except for the parameters in the following table and the electrode material not containing component B, other parameters and preparation methods are the same as those in Example 1-1.

[0061] Table 2: Comparative Examples 3-1 to 3-7

[0062]

[0063] It can be seen from the results of Comparative Example 3-1 and Comparative Example 2-3 that by adding lithium oxalate to the positive electrode, it has a certain lithium compensation function and can slightly improve the cycle performance of the battery. However, lithium oxalate is insoluble in the electrolyte, and it is easy to lose the lithium compensation performance after being passivated on the surface, resulting in limited improvement in performance. It can be seen from the results of Comparative Example 3-1 and Comparative Examples 3-2 to 3-7 that adding lithium difluorophosphate and lithium fluorosulfonate or their complexes to the electrolyte is beneficial to improving the cycle performance and high-temperature storage performance. It can be seen from the results of Examples 1-1 to 1-12, Comparative Examples 2-1 to 2-3 and Comparative Examples 3-1 to 3-7 that adding Components A and B to the battery simultaneously exhibits more excellent cycle performance and high-temperature performance. The main reason is that during the formation and subsequent cycling process of the battery, BF3 or PF5 in Component A reacts with lithium oxalate or lithium fluoride in Component B, and Component B that is insoluble in the electrolyte is converted into lithium compounds such as lithium difluorooxalate borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoroborate that are soluble in the electrolyte through a chemical reaction method, playing a role of in-situ continuous lithium compensation. Moreover, the lithium difluorooxalate borate anion or lithium difluorobis(oxalato)phosphate anion formed during this process can be further used to repair the interface film. Therefore, this combination method has more excellent performance than using lithium oxalate or lithium fluoride alone in the electrode material or using Component A alone in the electrolyte.

[0064] Example 2

[0065] This example provides a lithium-ion battery capable of in-situ lithium compensation, and its preparation method includes the following steps:

[0066] (1) Preparation of the electrolyte

[0067] In a glove box under an argon atmosphere (H2O < 1 ppm), prepare the following electrolyte formulation by mass percentage: 12.5% LiPF6, 2% VC, 0.5% PS, 5% FSO3Li·PF5, EC / DMC / EMC = 40 / 40 / 20 (volume ratio), stir well, and the electrolyte of the lithium secondary battery of the present invention is obtained (free acid < 15 ppm, moisture < 10 ppm).

[0068] (2) Preparation of the positive electrode sheet

[0069] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 3% in an NMP solution, add lithium cobaltate with a mass percentage of 92%, 2% conductive agent, 2.5% lithium fluoride, and 0.5% dispersant to the above solution and mix evenly. After coating the mixed slurry on both sides of the aluminum foil, dry and roll it to obtain the positive electrode sheet.

[0070] (3) Preparation of the negative electrode sheet

[0071] Dissolve an SBR binder with a mass percentage of 4% and a CMC thickener with a mass percentage of 1% in an aqueous solution. Add hard carbon with a mass percentage of 95% to the above solution and mix evenly. After coating the mixed slurry on both sides of the copper foil, dry it and roll it to obtain a negative electrode sheet.

[0072] (4) Fabrication of lithium-ion battery

[0073] Make a square battery cell by winding the above-prepared positive electrode sheet, negative electrode sheet and separator, package it with a polymer, pour in the above-prepared electrolyte, and fabricate a lithium-ion battery through processes such as formation.

[0074] Example 3

[0075] This example provides a lithium-ion battery capable of in-situ lithium supplementation, and its preparation method includes the following steps:

[0076] (1) Preparation of electrolyte

[0077] In a glove box under an argon atmosphere (H2O < 1 ppm), prepare the following electrolyte formulation by mass percentage: 12.5% LiPF6, 2% VC, 0.5% PS, 5% FSO3Li·BF3, DEC / DMC / EMC = 40 / 40 / 20 (volume ratio). Stir well to obtain the electrolyte for the lithium secondary battery of the present invention (free acid < 15 ppm, moisture < 10 ppm).

[0078] (2) Preparation of positive electrode sheet

[0079] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 3% in an NMP solution. Add lithium cobaltate with a mass percentage of 94%, a conductive agent with a mass percentage of 2% and a dispersant with a mass percentage of 1% to the above solution and mix evenly. After coating the mixed slurry on both sides of the aluminum foil, dry it and roll it to obtain a positive electrode sheet.

[0080] (3) Preparation of negative electrode sheet

[0081] Dissolve an SBR binder with a mass percentage of 4% and a CMC thickener with a mass percentage of 1% in an aqueous solution. Add hard carbon with a mass percentage of 93% and lithium oxalate with a mass percentage of 2% to the above solution and mix evenly. After coating the mixed slurry on both sides of the copper foil, dry it and roll it to obtain a negative electrode sheet.

[0082] (4) Fabrication of lithium-ion battery

[0083] Make a square battery cell by winding the above-prepared positive electrode sheet, negative electrode sheet and separator, package it with a polymer, pour in the above-prepared electrolyte, and fabricate a lithium-ion battery through processes such as formation.

[0084] Example 4

[0085] This embodiment provides a sodium-ion battery capable of in-situ sodium replenishment, and its preparation method includes the following steps:

[0086] (1) Preparation of electrolyte

[0087] In a glove box under an argon atmosphere (H2O < 1 ppm), prepare the following electrolyte according to mass percentage: 12.5% NaPF6, 2% ethylene carbonate, 0.5% fluoroethylene carbonate, 5% NaPO2F2·PF5, DEC / DMC / EMC = 40 / 40 / 20 (volume ratio), stir well, and the electrolyte of the sodium secondary battery described in the present invention is obtained (free acid < 15 ppm, moisture < 10 ppm).

[0088] (2) Preparation of positive electrode sheet

[0089] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 3% in NMP solution, add sodium cobaltate with a mass percentage of 94%, conductive agent with a mass percentage of 2%, sodium oxalate with a mass percentage of 2.5% and dispersant with a mass percentage of 0.3% to the above solution and mix evenly. After coating the mixed slurry on both sides of the aluminum foil, dry and roll to obtain the positive electrode sheet.

[0090] (3) Preparation of negative electrode sheet

[0091] Dissolve SBR binder with a mass percentage of 4% and CMC thickener with a mass percentage of 1% in an aqueous solution, add hard carbon with a mass percentage of 95% to the above solution, mix evenly, coat the mixed slurry on both sides of the copper foil, dry and roll to obtain the negative electrode sheet.

[0092] (4) Fabrication of sodium-ion battery

[0093] Make the positive electrode sheet, negative electrode sheet and separator prepared above into a square battery cell in a winding manner, use polymer packaging, pour the electrolyte prepared above, and make a sodium-ion battery after processes such as formation.

[0094] Example 5

[0095] This embodiment provides a sodium-ion battery capable of in-situ sodium replenishment, and its preparation method includes the following steps:

[0096] (1) Preparation of electrolyte

[0097] In a glove box under an argon atmosphere (H2O < 1 ppm), an electrolyte solution with the following formula was prepared by mass percentage: 12.5% NaPF6, 2% 1,4-butanesultone, 0.5% vinylene sulfate, 5% FSO3Na·BF3, DEC / DMC / ethyl acetate = 40 / 50 / 10 (volume ratio). After stirring evenly, the electrolyte solution for the sodium secondary battery of the present invention was obtained (free acid < 15 ppm, water content < 10 ppm).

[0098] (2) Preparation of the positive electrode plate

[0099] Polyvinylidene fluoride (PVDF) with a mass percentage of 3% was dissolved in an NMP solution. Sodium cobaltate with a mass percentage of 94%, a conductive agent of 2.5%, and a dispersant of 0.5% were added to the above solution and mixed evenly. After the prepared slurry was coated on both sides of the aluminum foil, it was dried and rolled to obtain the positive electrode plate.

[0100] (3) Preparation of the negative electrode plate

[0101] An SBR binder with a mass percentage of 4% and a CMC thickener with a mass percentage of 1% were dissolved in an aqueous solution. Crystalline carbon with a mass percentage of 92.5% and sodium fluoride of 2.5% were added to the above solution and mixed evenly. After the prepared slurry was coated on both sides of the copper foil, it was dried and rolled to obtain the negative electrode plate.

[0102] (4) Fabrication of the sodium-ion battery

[0103] The positive electrode plate, negative electrode plate, and separator prepared above were made into a square battery cell in a winding manner, packaged with a polymer, and the electrolyte solution prepared above was poured in. After processes such as formation, a sodium-ion battery was made.

[0104] Example 6

[0105] This example provides a lithium-ion battery capable of in-situ lithium supplementation, and its preparation method includes the following steps:

[0106] (1) Preparation of the electrolyte solution

[0107] In a glove box under an argon atmosphere (H2O < 1 ppm), an electrolyte solution with the following formula was prepared by mass percentage: 12.5% LiPF6, 2% VC, 0.5% PS, 5% FSO3Li·PF5, EC / DMC / EMC = 40 / 40 / 20 (volume ratio). After stirring evenly, the electrolyte solution for the lithium secondary battery of the present invention was obtained (free acid < 15 ppm, water content < 10 ppm).

[0108] (2) Preparation of the positive electrode plate

[0109] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 3% in an NMP solution. Add lithium cobaltate with a mass percentage of 92%, a conductive agent with a mass percentage of 2%, lithium fluoride with a mass percentage of 2.5%, and a dispersant with a mass percentage of 0.5% to the above solution and mix evenly. After coating the mixed slurry on both sides of the aluminum foil, dry and roll it to obtain the positive electrode plate.

[0110] (3) Preparation of the negative electrode plate

[0111] Dissolve an SBR binder with a mass percentage of 3% and a CMC thickener with a mass percentage of 1% in an aqueous solution. Add hard carbon with a mass percentage of 92.5% and lithium fluoride with a mass percentage of 3.5% to the above solution, mix evenly. After coating the mixed slurry on both sides of the copper foil, dry and roll it to obtain the negative electrode plate.

[0112] (4) Fabrication of the lithium-ion battery

[0113] Make a square battery cell by winding the above-prepared positive electrode plate, negative electrode plate, and separator, package it with a polymer, pour the above-prepared electrolyte, and fabricate a lithium-ion battery through processes such as formation.

[0114] Example 7

[0115] This example provides a sodium-ion battery capable of in-situ sodium supplementation, and its preparation method includes the following steps:

[0116] (1) Preparation of the electrolyte

[0117] In a glove box under an argon atmosphere (H2O < 1 ppm), prepare the following electrolyte according to the mass percentage: 12.5% NaPF6, 2% 1,4-butanesultone, 0.5% vinylene sulfate, 5% FSO3Na·BF3, DEC / DMC / ethyl acetate = 40 / 50 / 10 (volume ratio), stir well, and obtain the electrolyte of the sodium secondary battery described in the present invention (free acid < 15 ppm, water content < 10 ppm).

[0118] (2) Preparation of the positive electrode plate

[0119] Dissolve polyvinylidene fluoride (PVDF) with a mass percentage of 2% in an NMP solution. Add sodium cobaltate with a mass percentage of 94%, a conductive agent with a mass percentage of 2%, sodium fluoride with a mass percentage of 1.5%, and a dispersant with a mass percentage of 0.5% to the above solution and mix evenly. After coating the mixed slurry on both sides of the aluminum foil, dry and roll it to obtain the positive electrode plate.

[0120] (3) Preparation of the negative electrode plate

[0121] Dissolve an SBR binder with a mass percentage of 4% and a CMC thickener with a mass percentage of 1% in an aqueous solution. Add crystalline carbon with a mass percentage of 92.5% and sodium fluoride with a mass percentage of 2.5% to the above solution, mix evenly. After coating the mixed slurry on both sides of the copper foil, dry it and roll it to obtain a negative electrode sheet.

[0122] (4) Fabrication of sodium-ion battery

[0123] Make the positive electrode sheet, negative electrode sheet and separator prepared above into a square battery cell in a winding manner, package it with a polymer, pour the electrolyte prepared above, and make a sodium-ion battery after processes such as formation.

[0124] For sodium-ion batteries, adding both Component A and Component B in the battery exhibits more excellent cycle performance and high-temperature performance. The main reason is that during the formation and subsequent cycling of the battery, BF3 or PF5 in Component A reacts with sodium oxalate or sodium fluoride in Component B, and converts Component B, which is insoluble in the electrolyte, into sodium compounds such as sodium difluorooxalate, sodium difluorobis(oxalato)phosphate, and sodium tetrafluoroborate that are soluble in the electrolyte through a chemical reaction, playing a role of continuously supplementing sodium in-situ. Moreover, the difluorooxalate borate anion or difluorobis(oxalato)phosphate anion formed in this process can be further used to repair the interface film. Therefore, this combination method has more excellent performance than using sodium oxalate or sodium fluoride alone in the electrode material or using Component A alone in the electrolyte.

[0125] According to the disclosure and teaching of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A battery capable of in-situ lithium or sodium supplementation, comprising a positive electrode sheet, a negative electrode sheet and an electrolyte, characterized in that: The electrolyte contains component A, and the positive electrode and / or negative electrode contains component B; The general structural formula of component A is XY, wherein X is lithium fluorosulfonate, sodium fluorosulfonate, lithium difluorophosphate or sodium difluorophosphate; Y is boron trifluoride or phosphorus pentafluoride; The component B is at least one of lithium oxalate, sodium oxalate, lithium fluoride and sodium fluoride.

2. The battery capable of in-situ lithium or sodium replenishment according to claim 1, characterized in that: The mass percentage of the component A in the electrolyte is 0.1% to 40%.

3. The battery capable of in-situ lithium or sodium replenishment according to claim 2, characterized in that: The mass percentage of the component A in the electrolyte is 0.3% to 30%.

4. The battery capable of in-situ lithium or sodium replenishment according to claim 1, characterized in that: The mass percentage of the component B in the positive electrode and / or the negative electrode is 0.1% to 20%.

5. The battery capable of in-situ lithium or sodium replenishment according to claim 4, characterized in that: The mass percentage of the component B in the positive electrode and / or the negative electrode is 0.2% to 15%.

6. The battery capable of in-situ lithium or sodium replenishment according to claim 1, characterized in that: The electrolyte further comprises a conductive lithium salt or a conductive sodium salt, a non-aqueous organic solvent and an additive.

7. The battery capable of in-situ lithium or sodium replenishment according to claim 6, characterized in that: The conductive lithium salt is at least one of LiBF4, LiPF6, LiAsF6, LiClO4, LiSO3CF3, LiB(C2O4)2, LiBF2C2O4, LiN(SO2CF3)2 and LiN(SO2F)2; the conductive sodium salt is at least one of NaBF4, NaPF6, NaAsF6, NaClO4, NaSO3CF3, NaB(C2O4)2, NaBF2C2O4, NaN(SO2CF3)2 and NaN(SO2F)2; The non-aqueous organic solvent is at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate and butyl propionate. The additive is at least one of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, 1,3-propane sultone, 1,4-butane sultone, vinyl sulfate, propylene sulfate, vinyl sulfite, propylene sulfite, succinonitrile, adiponitrile, 1,2-cyanoethoxyethane and hexanetrinitrile.

8. The battery capable of in-situ lithium or sodium replenishment according to claim 1, characterized in that: The positive electrode sheet and the negative electrode sheet both include an active material, a conductive agent, a current collector, and a binder for binding the active material and the conductive agent to the current collector; The positive electrode sheet includes a positive electrode active material capable of reversibly inserting / deinserting lithium or sodium ions, the positive electrode active material is a composite metal oxide of lithium or sodium, and the metal oxide includes oxides of nickel, cobalt, manganese elements and any combination thereof; The negative electrode sheet includes a negative electrode active material capable of accepting or releasing lithium or sodium ions, and the negative electrode active material includes lithium or sodium metal, lithium or sodium alloy, crystalline carbon, amorphous carbon, carbon fiber, hard carbon, and soft carbon; wherein the crystalline carbon includes natural graphite, graphitized coke, graphitized MCMB, and graphitized mesophase asphalt carbon fiber; the lithium or sodium alloy includes an alloy of lithium or sodium and aluminum, zinc, silicon, tin, gallium, and antimony metal.

9. The battery capable of in-situ lithium or sodium replenishment according to claim 8, characterized in that: The positive electrode active material further includes at least one of chemical elements, including Mg, Al, Ti, Sn, V, Ge, Ga, B, Zr, Cr, Fe, Sr and rare earth elements.

10. The battery capable of in-situ lithium or sodium replenishment according to claim 8, characterized in that: The positive electrode active material further includes a polyanion lithium compound LiM x (PO4) y , where M is Ni, Co, Mn, Fe, Ti, or V, 0≤x≤5, 0≤y≤5.

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