Interface control solution for pre-lithiation electrodes, preparation method and application

Abstract

The application discloses an interface control liquid for prelithiation electrodes, a preparation method and application, and the interface control liquid comprises a solvent and a metal salt; the solvent comprises one or more of an ether solvent, an ester solvent, a ketone solvent, a hydrocarbon solvent, a nitrile solvent or deionized water; the metal salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bisoxalate borate, lithium bisfluorosulfonimide, lithium bistrifluoromethylsulfonimide, lithium perchlorate, lithium fluoride and lithium chloride; the concentration of the metal salt is 0.001 g / mL-10 g / mL; the prelithiation electrode is obtained by supplementing lithium to an electrode by a chemical prelithiation solution; the interface control liquid is used for modifying the prelithiation electrode, the metal salt of the interface control liquid reacts with the chemical prelithiation solution remaining on the surface of the prelithiation electrode, and a solid electrolyte layer containing inorganic lithium salt is generated on the surface of the prelithiation electrode; wherein, the content of the inorganic lithium salt is between 5% and 90%.

Description

Technical Field

[0001] This invention relates to the field of lithium battery materials technology, and in particular to an interface control liquid for pre-lithiation electrodes, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in 3C (computers, communications, and consumer electronics) and electric vehicles due to their high specific energy, high volumetric energy density, low self-discharge, and long lifespan. Over the past 30 years, significant breakthroughs have been achieved in lithium-ion battery research regarding energy density, cost, and safety, with energy density approaching the limits of existing electrode materials. However, in practical applications, the presence of some irreversible changes in the electrode structure and the tendency of electrode materials to react with the electrolyte, consuming active lithium, results in a lower initial coulombic efficiency, thus affecting the overall energy density of the lithium-ion battery.

[0003] Pre-lithiation refers to storing a certain amount of active lithium in the electrode or material before a battery charge-discharge cycle to offset the irreversible lithium loss in the first cycle. Pre-lithiation technology has become an important process for improving battery efficiency and energy density in the first cycle. Currently reported pre-lithiation methods include pre-lithiation for electrode materials and pre-lithiation for electrode sheets. Specifically, these include doping pre-lithiation, contact pre-lithiation, electrochemical pre-lithiation, and chemical pre-lithiation. Doping pre-lithiation involves mixing metallic lithium or other materials with high lithium storage capacity with the electrode material to obtain composite electrode materials or electrode sheets; contact pre-lithiation involves directly contacting metallic lithium with the positive / negative electrode material or electrode sheet to achieve pre-lithiation of the positive / negative electrode; electrochemical pre-lithiation involves pre-embedding a certain amount of lithium ions into the positive / negative electrode material or electrode sheet through electrochemical methods; chemical pre-lithiation involves soaking the positive / negative electrode material or electrode sheet in a lithium-ion-rich solution to embed a certain amount of additional active lithium to achieve a lithium replenishment effect. Pre-lithiation treated electrode materials or electrode sheets contain high levels of active lithium, making them sensitive to air and prone to contamination or deactivation by reacting with oxygen, water, carbon dioxide, etc. in the air, which is detrimental to experimental production operations and electrochemical performance.

[0004] Currently, pre-lithiation processes only consider increasing the lithium content of electrode materials or electrodes, with little consideration given to controlling the interfacial properties of these materials or electrodes. However, the interfacial properties of electrode materials or electrodes significantly impact the electrochemical and safety performance of batteries. During cycling, the active materials of electrodes readily react with the electrolyte, forming a solid electrolyte layer on the electrode surface. This affects charge transfer and ion transport at the interface, thus impacting battery electrochemical performance. This interfacial layer formed by the electrochemical process cannot be precisely controlled. However, the interfacial properties of materials or electrodes can be artificially and controllably adjusted by pre-forming a stable functional interfacial layer on the electrode surface through chemical or electrochemical processes. Existing artificial interface control only targets the original electrode materials or electrodes, rarely addressing the interface of pre-lithiated electrode materials or electrodes. For pre-lithiated electrode materials or electrodes, due to their higher electrochemical activity, it is easier to control the solid electrolyte layer. If a stable interfacial layer can be preferentially formed on the electrode surface through surface treatment, it can not only improve the cycling performance of the electrode but also prevent uncontrollable electrochemical reactions between the electrode materials and the electrolyte inside the battery.

[0005] Patent CN113193174A discloses an interface pretreatment solution for silicon-oxygen pre-lithiation anodes, its preparation method, and its application. The treated electrode is a lithium-replenishing electrode obtained by directly depositing a layer of lithium metal on the surface of the anode film. The interface control solution uses lithium sulfide, aluminum iodide, aluminum bromide, lithium nitrate, or copper nitride as the solute. The solute reacts directly with the metallic lithium on the lithium-replenishing electrode, and the resulting product effectively inhibits lithium dendrite growth and side reactions, making the solid electrolyte interphase (SEI) film formed on the surface of the pre-lithiation anode more stable. However, because the interface control solution in this patent reacts directly with the metallic lithium on the lithium-replenishing electrode, it leads to the loss of active lithium in the anode film, weakening the lithium replenishment effect and affecting the battery's energy density. It cannot fully achieve the purpose of pre-lithiation, and the interface pretreatment solution in this patent does not show any improvement in the electrode's stability to air. Summary of the Invention

[0006] This invention provides an interface control liquid, preparation method, and application for pre-lithiated electrodes. For chemically pre-lithiated electrodes, the interface of the pre-lithiated electrode is controlled using an interface control liquid. The metal salt of the interface control liquid reacts with the residual chemical pre-lithiation solution on the surface of the pre-lithiated electrode, forming a solid electrolyte layer containing inorganic lithium salts on the surface of the pre-lithiated electrode. This not only effectively maintains the lithium replenishment effect of pre-lithiation on the electrode but also controls the electrode interface composition. Furthermore, the content of the generated inorganic lithium salts is higher than that generated by the electrochemical reaction between the electrode and the electrolyte, exhibiting good mechanical properties and electrochemical stability. It effectively suppresses lithium dendrite growth and side reactions, avoiding uncontrollable electrochemical reactions between the electrode material and the electrolyte inside the battery, and further improving the battery's cycle performance. Simultaneously, the pre-lithiated electrode treated with the interface control liquid of this invention exhibits air stability.

[0007] In a first aspect, embodiments of the present invention provide an interface control liquid for a pre-lithiated electrode, the interface control liquid comprising: a solvent and a metal salt;

[0008] The solvent includes one or more of the following: ether solvents, ester solvents, ketone solvents, hydrocarbon solvents, nitrile solvents, or deionized water;

[0009] The metal salt includes one or more of the following: lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium fluoride, and lithium chloride; the concentration of the metal salt is 0.001 g / mL to 10 g / mL.

[0010] The pre-lithiation electrode is obtained by adding lithium to the electrode using a chemical pre-lithiation solution;

[0011] The interface control liquid modifies the pre-lithiation electrode. The metal salt of the interface control liquid reacts with the chemical pre-lithiation solution remaining on the surface of the pre-lithiation electrode to generate a solid electrolyte layer containing inorganic lithium salt on the surface of the pre-lithiation electrode. The content of the inorganic lithium salt is between 5% and 90%.

[0012] Preferably, the content of the inorganic lithium salt is between 40% and 90%;

[0013] The solvent specifically includes one or more of the following: methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, dimethyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butenyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, trimethylene carbonate, chloroethylene carbonate, vinylene carbonate, or deionized water;

[0014] The chemical pre-lithiation solution includes one or more of the following: lithium biphenyl-dimethyltetrahydrofuran solution, lithium biphenyl-tetrahydrofuran solution, lithium biphenyl-ethylene glycol dimethyl ether solution, tetramethyl lithium biphenyl-dimethyltetrahydrofuran solution, tetramethyl lithium biphenyl-tetrahydrofuran solution, tetramethyl lithium biphenyl-ethylene glycol dimethyl ether solution, lithium naphthalene-dimethyltetrahydrofuran solution, lithium naphthalene-tetrahydrofuran solution, lithium naphthalene-ethylene glycol dimethyl ether solution, or liquid ammonia-lithium solution.

[0015] Preferably, the interface control liquid further includes conductive additives; the conductive additives specifically include one or more of the following: carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, graphene oxide, carbon fiber, and carbon quantum dots.

[0016] The interface control liquid further includes a binder; the binder specifically includes one or more of the following: polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, polyvinyl alcohol, polybutyl acrylate, and polyacrylonitrile;

[0017] The interface control liquid also includes functional fillers; the functional fillers specifically include one or more of the following: boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder, and aluminum powder.

[0018] Preferably, the active material of the pre-lithiated electrode includes one or more of the following: lithium iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium-rich ternary materials, lithium nickel manganese oxide, copper fluoride, cobalt fluoride, cobalt fluoride, iron fluoride, ferrous fluoride, manganese fluoride, nickel fluoride, zinc fluoride, niobium fluoride, molybdenum chloride, iron chloride, iron tetroxide, vanadium pentoxide, nickel sulfide, cobalt sulfide, silicon sulfide, tetraphosphorus heptasulfide, diphosphorus pentasulfide, copper oxide, strontium oxide, cobalt oxide, ferric oxide, manganese dioxide, molybdenum dioxide, molybdenum trioxide, lithium titanate, lithium vanadate, silicon-carbon composite material, silicon suboxide-carbon composite material, silicon suboxide, silicon dioxide, natural graphite, artificial graphite, graphene, carbon nanotubes, and carbon nanofibers.

[0019] In a second aspect, embodiments of the present invention provide a method for preparing the interface control liquid for a pre-lithiation electrode as described in the first aspect above, the preparation method comprising:

[0020] The solvent and metal salt are mixed in a certain proportion to obtain a metal salt solution;

[0021] In an inert atmosphere with an ambient temperature between -10℃ and 100℃, the metal salt solution is mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode.

[0022] The solvent includes one or more of the following: ether solvents, ester solvents, ketone solvents, hydrocarbon solvents, nitrile solvents, or deionized water;

[0023] The metal salt includes one or more of the following: lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium fluoride, and lithium chloride; the concentration of the metal salt is 0.001 g / mL to 10 g / mL.

[0024] The pre-lithiation electrode is obtained by adding lithium to the electrode using a chemical pre-lithiation solution;

[0025] The interface control liquid modifies the pre-lithiation electrode. The metal salt of the interface control liquid reacts with the chemical pre-lithiation solution remaining on the surface of the pre-lithiation electrode to generate a solid electrolyte layer containing inorganic lithium salt on the surface of the pre-lithiation electrode. The content of the inorganic lithium salt is between 5% and 90%.

[0026] Preferably, the content of the inorganic lithium salt is between 40% and 90%;

[0027] The solvent specifically includes one or more of the following: methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, dimethyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butenyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, trimethylene carbonate, chloroethylene carbonate, vinylene carbonate, or deionized water;

[0028] The chemical pre-lithiation solution includes one or more of the following: lithium biphenyl-dimethyltetrahydrofuran solution, lithium biphenyl-tetrahydrofuran solution, lithium biphenyl-ethylene glycol dimethyl ether solution, tetramethyllithium biphenyl-dimethyltetrahydrofuran solution, tetramethyllithium biphenyl-tetrahydrofuran solution, tetramethyllithium biphenyl-ethylene glycol dimethyl ether solution, lithium naphthalene-dimethyltetrahydrofuran solution, lithium naphthalene-tetrahydrofuran solution, lithium naphthalene-ethylene glycol dimethyl ether solution, or liquid ammonia-lithium solution;

[0029] The interface control liquid also includes conductive additives; the conductive additives specifically include one or more of the following: carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, graphene oxide, carbon fiber, and carbon quantum dots.

[0030] The interface control liquid further includes a binder; the binder specifically includes one or more of the following: polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, polyvinyl alcohol, polybutyl acrylate, and polyacrylonitrile;

[0031] The interface control liquid also includes functional fillers; the functional fillers specifically include one or more of the following: boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder, and aluminum powder.

[0032] Preferably, the magnetic stirring speed is between 50 rpm and 2000 rpm, and the magnetic stirring time is between 1 second and 48 hours.

[0033] Thirdly, embodiments of the present invention provide an interface control method for a pre-lithiated electrode, the interface control method comprising: contacting the pre-lithiated electrode with the interface control liquid phase described in the first aspect in an inert atmosphere;

[0034] The pre-lithiated electrode, after being in contact with the interface-controlled liquid phase, is air-dried or oven-dried to obtain the interface-controlled pre-lithiated electrode.

[0035] The pre-lithiated electrode with the modified interface exhibits stability against air.

[0036] Preferably, the contact method is immersion and static contact; the immersion and static contact is carried out under a temperature condition of -40℃ to 200℃, and the contact reaction time is between 1 second and 72 hours;

[0037] The drying temperature is between -10℃ and 300℃;

[0038] The active material of the pre-lithiated electrode includes one or more of the following: lithium iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium-rich ternary materials, lithium nickel manganese oxide, copper fluoride, cobalt fluoride, cobalt fluoride, iron fluoride, ferrous fluoride, manganese fluoride, nickel fluoride, zinc fluoride, niobium fluoride, molybdenum chloride, iron chloride, iron tetroxide, vanadium pentoxide, nickel sulfide, cobalt sulfide, silicon sulfide, tetraphosphorus heptasulfide, diphosphorus pentasulfide, copper oxide, strontium oxide, cobalt oxide, ferric oxide, manganese dioxide, molybdenum dioxide, molybdenum trioxide, lithium titanate, lithium vanadate, silicon-carbon composite material, silicon suboxide-carbon composite material, silicon suboxide, silicon dioxide, natural graphite, artificial graphite, graphene, carbon nanotubes, and carbon nanofibers.

[0039] Fourthly, embodiments of the present invention provide a lithium battery comprising the pre-lithiated electrode with interface modulation as described in the third aspect above.

[0040] This invention provides an interface control liquid for pre-lithiated electrodes. For chemically pre-lithiated electrodes, the interface of the pre-lithiated electrode is controlled using the interface control liquid. The metal salt of the interface control liquid reacts with the residual chemical pre-lithiated solution on the surface of the pre-lithiated electrode, forming a solid electrolyte layer containing inorganic lithium salts on the surface of the pre-lithiated electrode. This not only effectively maintains the lithium replenishment effect of pre-lithiation on the electrode but also controls the electrode interface composition. Furthermore, the content of the generated inorganic lithium salts is higher than that generated by the electrochemical reaction between the electrode and the electrolyte, exhibiting good mechanical properties and electrochemical stability. It effectively suppresses lithium dendrite growth and side reactions, avoids uncontrollable electrochemical reactions between the electrode materials and the electrolyte inside the battery, and is more conducive to improving the battery's cycle performance.

[0041] The pre-lithiated electrode sheet, after interface modulation, exhibits good stability in air and is suitable for existing lithium-ion battery processing technologies, providing a possibility for the pre-lithiation of lithium-ion battery electrode materials and the development of high-energy-density batteries. Furthermore, the stability of the pre-lithiated electrode sheet in air can be improved by controlling the composition of the electrode interface layer, thus making the pre-lithiation technology more adaptable to current battery manufacturing processes and easier to promote. This invention uses an interface modulation liquid to modulate the interface of the pre-lithiated electrode. It is simple to operate, uses readily available raw materials, is highly safe, and has strong applicability. It is of great significance for the application of pre-lithiated electrode sheets and the improvement of battery electrochemical performance, and has broad prospects and practical value. Attached Figure Description

[0042] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0043] Figure 1 This is a flowchart of the preparation method of the interface-regulating liquid provided in the embodiments of the present invention;

[0044] Figure 2 This is a flowchart of the interface control method for the pre-lithiation electrode provided in an embodiment of the present invention;

[0045] Figure 3 These are the X-ray diffraction (XRD) patterns of the pre-lithiated electrodes after interface modulation provided in Examples 1-8 of this invention;

[0046] Figure 4 These are charge-discharge curves of batteries prepared by electrodes with interface control of pre-lithiated graphite electrodes provided in Examples 1-4 of this invention.

[0047] Figure 5 These are the coulombic efficiency curves of batteries prepared by electrodes with pre-lithiated graphite electrode interface controlled according to Examples 1-4 of the present invention.

[0048] Figure 6 These are charge-discharge curves of batteries prepared by electrodes with pre-lithiated graphite electrode interface controlled according to Examples 5-8 of the present invention.

[0049] Figure 7 These are the coulombic efficiency curves of batteries prepared by electrodes with interface modulation of pre-lithiated graphite electrodes provided in Examples 5-8 of this invention.

[0050] Figure 8 These are the XRD patterns of the graphite electrode of Comparative Example 1 and the pre-lithiated graphite electrode of Comparative Example 2 without interface control of the present invention.

[0051] Figure 9 These are charge-discharge curves of batteries prepared by the graphite electrode of Comparative Example 1 and the pre-lithiated graphite electrode without interface control in Comparative Example 2 of the present invention.

[0052] Figure 10 This is a coulombic efficiency curve of the batteries prepared by the graphite electrode of Comparative Example 1 and the pre-lithiated graphite electrode without interface control of Comparative Example 2. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. However, it should be understood that these embodiments are only for more detailed description and should not be construed as limiting the present invention in any way, that is, not intended to limit the scope of protection of the present invention.

[0054] This invention provides an interface control liquid for a pre-lithiation electrode, the interface control liquid comprising: a solvent and a metal salt; the pre-lithiation electrode is obtained by replenishing lithium to the electrode with a chemical pre-lithiation solution;

[0055] An interface control solution is used to modify the pre-lithiation electrode. The metal salt of the interface control solution reacts with the chemical pre-lithiation solution remaining on the surface of the pre-lithiation electrode to form a solid electrolyte layer containing inorganic lithium salts on the surface of the pre-lithiation electrode. Among them, the inorganic lithium salts mainly include Li2CO3 and LiF. Li2CO3 can improve the diffusion rate of lithium ions, and LiF can inhibit the formation of lithium dendrites.

[0056] In this embodiment of the invention, the content of inorganic lithium salt generated by the metal salt in the interface control liquid and the residual chemical pre-lithiation solution on the surface of the pre-lithiation electrode ranges from 5% to 90%, preferably 40% to 90%, which is higher than the content of inorganic lithium salt generated by the electrochemical reaction between a conventional electrode and the electrolyte. This is because, compared to the slow ion transport process during the charging and discharging of a battery, the reaction between the metal salt in the interface control liquid of this invention and the residual chemical pre-lithiation solution on the surface of the pre-lithiation electrode is faster and more complete, which is more conducive to the formation of inorganic lithium salt components with higher stability.

[0057] Organic lithium salts, mainly alkyl lithium esters, are inevitably generated during the reaction between the electrolyte and electrode materials inside the battery. These can separate the electrolyte from the electrode materials. However, alkyl lithium esters have poor ionic conductivity and poor stability. This invention increases the content of inorganic lithium salts in the electrolyte layer by using an interface control liquid, thereby reducing the proportion of organic lithium salts, giving full play to the role of inorganic lithium salts, and improving the stability of the solid electrolyte layer.

[0058] Therefore, the inorganic lithium salt generated by the reaction of the interface control liquid of the present invention with the chemical pre-lithiation solution remaining on the surface of the pre-lithiation electrode has good mechanical and electrochemical properties, can effectively inhibit the growth of lithium dendrites and the occurrence of side reactions, and make the SEI film formed on the surface of the pre-lithiation negative electrode more stable.

[0059] The solvents of the interface control liquid include one or more of the following: ether solvents, ester solvents, ketone solvents, hydrocarbon solvents, nitrile solvents, and water; specifically, the solvents include one or more of the following: methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, dimethyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butenyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, trimethylene carbonate, chloroethylene carbonate, vinylene carbonate, and deionized water;

[0060] The metal salts include one or more of the following: lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium fluoride, and lithium chloride; the concentration of the metal salt is 0.001 g / mL to 10 g / mL.

[0061] The pre-lithiation solutions used for chemical pre-lithiation of the electrode include one or more of the following: lithium biphenyl-dimethyltetrahydrofuran solution, lithium biphenyl-tetrahydrofuran solution, lithium biphenyl-ethylene glycol dimethyl ether solution, tetramethyl lithium biphenyl-dimethyltetrahydrofuran solution, tetramethyl lithium biphenyl-tetrahydrofuran solution, tetramethyl lithium biphenyl-ethylene glycol dimethyl ether solution, lithium naphthalene-dimethyltetrahydrofuran solution, lithium naphthalene-tetrahydrofuran solution, lithium naphthalene-ethylene glycol dimethyl ether solution, and liquid ammonia-lithium solution.

[0062] In optional solutions, the interface conditioning fluid may also include conductive additives, binders, and functional fillers.

[0063] The conductive additives specifically include one or more of the following: carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, graphene oxide, carbon fiber, and carbon quantum dots; the concentration of the conductive additives is 0-10 g / mL.

[0064] The adhesive specifically includes one or more of the following: polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, polyvinyl alcohol, polybutylene acrylate, and polyacrylonitrile; the concentration of the adhesive is 0-10 g / mL.

[0065] Functional fillers specifically include one or more of the following: boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder, and aluminum powder; the concentration of functional fillers is 0-10 g / mL. Functional fillers can play a role in flame retardancy and improving the thermal conductivity efficiency of the electrode interface, thereby improving the safety performance of the battery and reducing the risk of thermal failure.

[0066] This invention provides a method for preparing the interface control liquid for a pre-lithiated electrode according to the first aspect described above, such as... Figure 1 As shown, the preparation method includes:

[0067] Step 110: Mix the solvent and metal salt in a certain proportion to obtain a metal salt solution;

[0068] The solvents include one or more of the following: ether solvents, ester solvents, ketone solvents, hydrocarbon solvents, nitrile solvents, or deionized water; specifically, they include one or more of the following: methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, dimethyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butenyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, trimethylene carbonate, chloroethylene carbonate, vinylene carbonate, or deionized water.

[0069] The metal salts include one or more of the following: lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bis(oxalato)borate, lithium difluorosulfonate imide, lithium bis(trifluoromethanesulfonyl)imide, lithium perchlorate, lithium fluoride, and lithium chloride; the concentration of the metal salt is 0.001 g / mL to 10 g / mL.

[0070] In optional solutions, the interface control liquid also includes conductive additives; the conductive additives specifically include one or more of the following: carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, graphene oxide, carbon fiber, and carbon quantum dots; the concentration of the conductive additives is 0-10 g / mL.

[0071] The interface control liquid also includes a binder; the binder specifically includes one or more of the following: polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, polyvinyl alcohol, polybutylene acrylate, and polyacrylonitrile; the concentration of the conductive additive is 0-10 g / mL;

[0072] The interface conditioning fluid also includes functional fillers; the functional fillers specifically include one or more of the following: boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder, and aluminum powder; the concentration of the functional fillers is 0-10 g / mL; the function of the functional fillers is to retard flame and improve the thermal conductivity of the electrode interface, which can improve the safety performance of the battery and reduce the risk of thermal failure.

[0073] Step 120: Under an inert atmosphere and at an ambient temperature between -10℃ and 100℃, the metal salt solution is mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode.

[0074] The magnetic stirring speed ranges from 50 rpm to 2000 rpm, and the magnetic stirring time ranges from 1 second to 48 hours.

[0075] The pre-lithiation electrode is obtained by replenishing lithium to the electrode with a chemical pre-lithiation solution; the chemical pre-lithiation solution includes one or more of the following: lithium biphenyl-dimethyltetrahydrofuran solution, lithium biphenyl-tetrahydrofuran solution, lithium biphenyl-ethylene glycol dimethyl ether solution, tetramethyl lithium biphenyl-dimethyltetrahydrofuran solution, tetramethyl lithium biphenyl-tetrahydrofuran solution, tetramethyl lithium biphenyl-ethylene glycol dimethyl ether solution, lithium naphthalene-dimethyltetrahydrofuran solution, lithium naphthalene-tetrahydrofuran solution, lithium naphthalene-ethylene glycol dimethyl ether solution, and liquid ammonia-lithium solution.

[0076] This invention provides an interface control method for a pre-lithiation electrode, such as... Figure 2 As shown, the interface control methods include:

[0077] Step 210: In an inert atmosphere, the pre-lithiated electrode is brought into contact with the above-mentioned interface-controlled liquid phase.

[0078] The contact method is immersion and static contact; the immersion and static contact is carried out under conditions of -40℃ to 200℃, and the contact reaction time is between 1 second and 72 hours. During the contact reaction, the metal salt in the interface control solution reacts with the chemical pre-lithiation solution remaining on the surface of the pre-lithiation electrode to form a solid electrolyte layer containing inorganic lithium salt on the surface of the pre-lithiation electrode; wherein, the content of inorganic lithium salt is higher than the content of inorganic lithium salt generated by the electrochemical reaction between the electrode and the electrolyte, and the content of inorganic lithium salt is between 5% and 90%, preferably 40% to 90%.

[0079] Step 220: Allow the pre-lithiated electrode in contact with the interface control liquid to air dry or dry it by baking to obtain the pre-lithiated electrode after interface control.

[0080] The drying temperature is between -10℃ and 300℃.

[0081] The interface control liquid provided in this invention embodiment can be applied to various types of pre-lithiation electrodes. The active materials of the pre-lithiation electrodes include: lithium iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium-rich ternary materials, lithium nickel manganese oxide, copper fluoride, cobalt fluoride, cobalt fluoride, iron fluoride, ferrous fluoride, manganese fluoride, nickel fluoride, zinc fluoride, niobium fluoride, molybdenum chloride, iron chloride, iron tetroxide, vanadium pentoxide, nickel sulfide, cobalt sulfide, silicon sulfide, tetraphosphorus heptasulfide, diphosphorus pentasulfide, copper oxide, strontium oxide, cobalt oxide, ferric oxide, manganese dioxide, molybdenum dioxide, molybdenum trioxide, lithium titanate, lithium vanadate, silicon-carbon composite material, silicon suboxide-carbon composite material, silicon suboxide, silicon dioxide, natural graphite, artificial graphite, graphene, carbon nanotubes, and carbon nanofibers, one or more of these.

[0082] The pre-lithiated electrode after interface modulation has stability against air.

[0083] This invention provides a lithium battery comprising a pre-lithiated electrode treated with the interface control liquid of this invention.

[0084] To better understand the technical solution provided by this invention, the following uses several specific examples to illustrate the preparation method, application, and performance testing of the interface control liquid of this invention.

[0085] Example 1

[0086] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0087] Preparation of pre-lithiated electrode sheet: The graphite electrode sheet is pre-lithiated using a 1 mol / L solution of lithium biphenyl dimethyltetrahydrofuran as the pre-lithiation reagent. The natural graphite electrode sheet is reacted with the pre-lithiation solution for 10 minutes to obtain a pre-lithiated graphite electrode sheet. The open-circuit voltage of the pre-lithiated graphite electrode sheet is 0.13V-0.14V.

[0088] Preparation process of interface control solution:

[0089] 1) Dissolve lithium hexafluorophosphate in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 1 g / mL.

[0090] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 1000 rpm, and the stirring time was 1 hour.

[0091] Interface control methods for pre-lithiated electrodes:

[0092] 1) Under an argon atmosphere at room temperature, immerse the pre-lithiated graphite electrode sheet in the interface control solution prepared above and allow it to stand in contact for 10 minutes.

[0093] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0094] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0095] Electrochemical tests were conducted using a coin cell assembled with the interface-modified pre-lithiated electrode prepared in this embodiment. The pre-lithiated electrode was used as the positive electrode, lithium metal as the negative electrode, and a mixed solution of LiPF6 and ethylene carbonate / dimethyl carbonate (EC / DMC) as the electrolyte. Constant current charge-discharge mode tests were performed using a charge-discharge apparatus. The discharge cutoff voltage was 0.005V, and the charge cutoff voltage was 3V. The first week of charge-discharge tests were conducted at a current density of 0.05C, and subsequent discharge tests were conducted at a current density of 0.2C. The charge-discharge curves are shown below. Figure 4 As shown, the Coulomb efficiency curve is as follows: Figure 5 As shown.

[0096] Example 2

[0097] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0098] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0099] Preparation process of interface control solution:

[0100] 1) Dissolve lithium difluorosulfonate imine in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:2) to obtain a solution with a lithium salt concentration of 5 g / mL.

[0101] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 2000 rpm, and the stirring time was 0.5 hours.

[0102] Interface control methods for pre-lithiated electrodes:

[0103] 1) Under an argon atmosphere at room temperature, the pre-lithiated graphite electrode sheet was immersed in the above interface control solution and allowed to stand in contact for 2 hours for reaction.

[0104] 2) Take out the pre-lithiated graphite electrode sheet that is in contact with the interface control liquid and dry it under vacuum at 80°C to obtain the pre-lithiated electrode after interface control.

[0105] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0106] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 4 As shown, the Coulomb efficiency curve is as follows: Figure 5 As shown.

[0107] Example 3

[0108] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0109] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0110] Preparation process of interface control solution:

[0111] 1) Dissolve lithium perchlorate in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 0.5 g / mL.

[0112] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 50 rpm, and the stirring time was 12 hours.

[0113] Interface control methods for pre-lithiated electrodes:

[0114] 1) Under an argon atmosphere at room temperature, the pre-lithiated graphite electrode sheet was immersed in the above interface control solution and allowed to stand in contact for 1 hour.

[0115] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0116] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0117] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 4 As shown, the Coulomb efficiency curve is as follows: Figure 5 As shown.

[0118] Example 4

[0119] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0120] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0121] Preparation process of interface control solution:

[0122] 1) Dissolve lithium hexafluorophosphate in propylene carbonate solvent to obtain a solution with a lithium salt concentration of 0.1 g / mL.

[0123] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 1000 rpm, and the stirring time was 4 hours.

[0124] Interface control methods for pre-lithiated electrodes:

[0125] 1) Under an argon atmosphere at room temperature, the pre-lithiated graphite electrode sheet was immersed in the above interface control solution and allowed to stand in contact for 48 hours.

[0126] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 100°C to obtain the pre-lithiated electrode after interface control.

[0127] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0128] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 4 As shown, the Coulomb efficiency curve is as follows: Figure 5 As shown.

[0129] Example 5

[0130] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0131] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0132] Preparation process of interface control solution:

[0133] 1) Lithium hexafluorophosphate and acetylene black were dissolved in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 10 g / mL and an acetylene black concentration of 0.1 g / mL.

[0134] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 1000 rpm, and the stirring time was 2 hours.

[0135] Interface control methods for pre-lithiated electrodes:

[0136] 1) Under an argon atmosphere at room temperature, immerse the pre-lithiated graphite electrode sheet in the above interface control solution and allow it to stand in contact for 10 minutes to react.

[0137] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0138] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0139] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 6 As shown, the Coulomb efficiency curve is as follows: Figure 7 As shown.

[0140] Example 6

[0141] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0142] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0143] Preparation process of interface control solution:

[0144] 1) Lithium difluorosulfonamide and carboxymethyl cellulose were dissolved in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 2 g / mL, wherein the concentration of carboxymethyl cellulose was 0.05 g / mL.

[0145] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain the interface control solution for the pre-lithiation electrode. The magnetic stirring speed was between 50 rpm and 2000 rpm, and the stirring time was between 1 second and 48 hours.

[0146] Interface control methods for pre-lithiated electrodes:

[0147] 1) Under an argon atmosphere at room temperature, immerse the pre-lithiated graphite electrode sheet in the above interface control solution and allow it to stand in contact for 10 minutes to react.

[0148] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0149] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0150] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 6 As shown, the Coulomb efficiency curve is as follows: Figure 7 As shown.

[0151] Example 7

[0152] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0153] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0154] Preparation process of interface control solution:

[0155] 1) Dissolve lithium hexafluorophosphate in fluoroethylene carbonate solvent to obtain a solution with a lithium salt concentration of 1 mol / L.

[0156] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 1000 rpm, and the stirring time was 1 hour.

[0157] Interface control methods for pre-lithiated electrodes:

[0158] 1) Under an argon atmosphere at room temperature, immerse the pre-lithiated graphite electrode sheet in the above interface control solution and allow it to stand in contact for 50 minutes.

[0159] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0160] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0161] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 6 As shown, the Coulomb efficiency curve is as follows: Figure 7 As shown.

[0162] Example 8

[0163] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0164] The process for preparing the pre-lithiated electrode is the same as in Example 1.

[0165] Preparation process of interface control solution:

[0166] 1) Lithium difluorosulfonate imine salt and nano-alumina powder were dissolved in fluoroethylene carbonate solvent to obtain a solution with a lithium salt concentration of 0.001 g / mL and an alumina concentration of 0.01 g / mL.

[0167] 2) Under an argon atmosphere, the solution was mixed uniformly by magnetic stirring to obtain the interface control solution for the pre-lithiation electrode. The magnetic stirring speed was between 2000 rpm, and the stirring time was 2 hours.

[0168] Interface control methods for pre-lithiated electrodes:

[0169] 1) Under an argon atmosphere at room temperature, immerse the pre-lithiated graphite electrode sheet in the above interface control solution and allow it to stand in contact for 10 minutes to react.

[0170] 2) Take out the pre-lithiated graphite electrode sheet in contact with the interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0171] The pre-lithiation electrode prepared in this embodiment with interface modulation was subjected to XRD testing, and the test images are shown below. Figure 3 As shown.

[0172] It should be noted that: Examples 1-8 all use graphite electrodes, and the research focuses on graphite electrodes. Ordinary graphite electrodes, after lithium intercalation, possess LiC... X Compound (LiC) X The compounds refer to compounds of different compositions of Li and C. These compounds are unstable in air and readily react with CO2 and H2O to form Li2CO3. At this point, the active lithium stored in the graphite electrode is consumed, and the lithium from the highly lithium-intercalated LiC is released. 12 LiC becomes a low-lithium-intercalated state 18 Even LiC 24 This weakens the lithium replenishment effect of the graphite electrode.

[0173] pass Figure 3 It can be seen that the peak positions of the pre-lithiated graphite electrodes after interface modulation in Examples 1-8 all exhibit LiC characteristics. 12 The composition shows that the chemical composition of Li and C in the pre-lithiated graphite electrodes after interface regulation in Examples 1-8 did not change significantly, thus proving that the pre-lithiated electrodes treated with the interface regulation liquid of the present invention have air stability.

[0174] The interface-modulated pre-lithiation electrode prepared in this embodiment was used to assemble a coin half-cell for electrochemical testing, which was performed using the same method as in Example 1. The charge-discharge curves are shown below. Figure 6 As shown, the Coulomb efficiency curve is as follows: Figure 7 As shown.

[0175] Example 9

[0176] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0177] Preparation of pre-lithiated electrode sheet: The silicon-carbon composite electrode sheet is pre-lithiated using a 1 mol / L tetramethylbiphenyl lithium-tetrahydrofuran solution as the pre-lithiation reagent. The silicon-carbon composite electrode sheet is reacted with the pre-lithiation solution for 30 minutes to obtain the pre-lithiated silicon-carbon composite electrode sheet.

[0178] Preparation process of interface control solution:

[0179] 1) Dissolve lithium hexafluorophosphate in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 10 g / mL.

[0180] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 1000 rpm, and the stirring time was 2 hours.

[0181] Interface control methods for pre-lithiated electrodes:

[0182] 1) Under an argon atmosphere at room temperature, the pre-lithiated silicon-carbon composite electrode sheet was immersed in the interface control solution prepared above and allowed to stand in contact for 30 minutes.

[0183] 2) Take out the pre-lithiated silicon-carbon composite electrode sheet with the contact interface control liquid and dry it under vacuum at 100°C to obtain the pre-lithiated electrode after interface control.

[0184] Example 10

[0185] This embodiment provides a process for preparing an interface control liquid and a method for interface control of a pre-lithiated electrode:

[0186] Preparation of pre-lithiated electrode: The nickel-cobalt-manganese ternary electrode was pre-lithiated using a 1 mol / L solution of lithium biphenyl-ethylene glycol dimethyl ether as the pre-lithiation reagent. The nickel-cobalt-manganese ternary electrode was reacted with the pre-lithiation solution for 20 minutes to obtain the pre-lithiated nickel-cobalt-manganese ternary electrode.

[0187] Preparation process of interface control solution:

[0188] 1) Dissolve lithium hexafluorophosphate in a mixed solvent of dimethyl carbonate and ethylene carbonate (volume ratio 1:1) to obtain a solution with a lithium salt concentration of 5 g / mL.

[0189] 2) Under an argon atmosphere at room temperature, the solution was mixed uniformly by magnetic stirring to obtain an interface control solution for the pre-lithiation electrode. The magnetic stirring speed was 800 rpm, and the stirring time was 1 hour.

[0190] Interface control methods for pre-lithiated electrodes:

[0191] 1) Under an argon atmosphere at room temperature, the pre-lithiated nickel-cobalt-manganese ternary electrode sheet was immersed in the interface control solution prepared above and allowed to stand in contact for 20 minutes.

[0192] 2) Take out the pre-lithiated nickel-cobalt-manganese ternary electrode sheet with the contact interface control liquid and dry it under vacuum at 60°C to obtain the pre-lithiated electrode after interface control.

[0193] To better illustrate the effects of the embodiments of the present invention, a comparative example is provided to be made with the embodiments described above.

[0194] Comparative Example 1

[0195] The raw graphite electrodes were left untreated, and their electrochemical performance was tested.

[0196] XRD tests were performed on the graphite electrode sheet of this comparative example. The test images are shown below. Figure 8 As shown.

[0197] Electrochemical tests were conducted using coin-type half-cells assembled from the graphite electrodes of this comparative example, following the same method as in Example 1. The charge-discharge curves are shown below. Figure 9 As shown, the Coulomb efficiency curve is as follows: Figure 10 As shown.

[0198] Comparative Example 2

[0199] Natural graphite electrodes were pre-lithiated using a lithium biphenyl-dimethyltetrahydrofuran solution (1 mol / L), but no interface control liquid was used for interface control of the pre-lithiated graphite electrodes. The batteries were directly assembled and tested, and the assembly and testing methods were the same as in Example 1.

[0200] XRD tests were performed on the pre-lithiated graphite electrode of this comparative example without interface modulation. The test images are shown below. Figure 8 As shown.

[0201] Electrochemical tests were conducted using a coin half-cell assembled with the pre-lithiated graphite electrode (without interface modulation) from this comparative example, following the same method as in Example 1. The charge-discharge curves are shown below. Figure 9 As shown, the Coulomb efficiency curve is as follows: Figure 10 As shown.

[0202] The test results of the cycle capacity and initial efficiency of the battery assembled with the interface-controlled pre-lithiated electrode prepared in the embodiments of the present invention are shown in Table 1.

[0203]

[0204] Table 1

[0205] The data comparison in Table 1 shows that the cycle capacity, cycle stability and initial efficiency of the batteries in Examples 1-8 and Comparative Example 2 are better than those of the battery in Comparative Example 1. This is because the original graphite used in Comparative Example 1 was not pre-lithiated and was not replenished with lithium, so the initial efficiency of the battery assembled therein was inferior to that of Examples 1-8 and Comparative Example 2.

[0206] The batteries assembled with pre-lithiated electrodes after interface regulation in Examples 1-8 exhibit better cycle capacity and cycle stability than the batteries assembled with pre-lithiated and untreated graphite electrodes in Comparative Example 2. This is because the residual pre-lithiated solution on the surface of the pre-lithiated graphite electrode in Comparative Example 2 affects the cycle capacity of the battery, reducing its cycle capacity. However, the interface regulation liquid in Examples 1-8 can react with the residual pre-lithiated solution on the surface of the pre-lithiated electrode, forming a solid electrolyte layer containing inorganic lithium salts on the surface of the pre-lithiated electrode. This not only effectively maintains the lithium replenishment effect of pre-lithiation on the electrode but also regulates the electrode interface composition. Furthermore, the content of the generated inorganic lithium salts is higher than that generated by the electrochemical reaction between the electrode and the electrolyte, exhibiting good mechanical properties and electrochemical stability. It can effectively inhibit lithium dendrite growth and reduce battery side reactions, which is more conducive to improving the cycle performance of the battery.

[0207] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An interface regulation method of a pre-lithiation electrode, characterized in that, The interface regulation method comprises: contacting a prelithiation electrode with an interface regulation liquid phase in an inert atmosphere; The prelithiation electrode after being contacted with the interface regulation liquid phase is naturally air-dried or oven-dried to obtain a prelithiation electrode after interface regulation; The prelithiation electrode after interface regulation has stability to air; The interface regulation liquid comprises: a solvent and a metal salt; The solvent comprises: one or more of an ether solvent, an ester solvent, a ketone solvent, a hydrocarbon solvent, a nitrile solvent or deionized water; The metal salt comprises: one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bisoxalate borate, lithium bisfluorosulfonimide, lithium bis-trifluoromethylsulfonimide, lithium perchlorate, lithium fluoride and lithium chloride; the concentration of the metal salt is 0.001 g / mL-10 g / mL; The prelithiation electrode is obtained by supplementing lithium to an electrode by a chemical prelithiation solution; the chemical prelithiation solution comprises: one or more of a lithium biphenyl-dimethyltetrahydrofuran solution, a lithium biphenyl-tetrahydrofuran solution, a tetramethyl lithium biphenyl-dimethyltetrahydrofuran solution, a tetramethyl lithium biphenyl-tetrahydrofuran solution, a lithium naphthalene-dimethyltetrahydrofuran solution, a lithium naphthalene-tetrahydrofuran solution and a liquid ammonia-lithium solution; The interface regulation liquid modifies the prelithiation electrode, the metal salt in the interface regulation liquid reacts with the chemical prelithiation solution remaining on the surface of the prelithiation electrode, and a solid electrolyte layer containing inorganic lithium salt is generated on the surface of the prelithiation electrode; wherein the content of the inorganic lithium salt is between 5% and 90%.

2. The method of interface regulation of prelithiated electrodes according to claim 1, wherein, The content of the inorganic lithium salt is between 40% and 90%; The solvent specifically comprises: one or more of methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butylene carbonate, methyl ethyl carbonate, fluorinated ethylene carbonate, trimethylene carbonate, chlorinated ethylene carbonate, vinylene carbonate or deionized water.

3. The method of interface regulation of prelithiated electrodes according to claim 1, wherein, The interface regulation liquid further comprises a conductive additive; the conductive additive specifically comprises: one or more of carbon black, acetylene black, ketjen black, carbon nanotubes, graphene, graphene oxide, carbon fibers and carbon quantum dots; The interface regulation liquid further comprises a binder; the binder specifically comprises: one or more of polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, butadiene-styrene rubber, polyvinyl alcohol, polybutyl acrylate and polyacrylonitrile; The interface regulation liquid further comprises a functional filler; the functional filler specifically comprises: one or more of boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder and aluminum powder.

4. The method of interface regulation of prelithiated electrodes according to claim 1, wherein, The active material of the pre-lithiated electrode comprises one or more of lithium iron phosphate, lithium cobaltate, lithium nickelate, lithium manganate, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium-rich ternary material, lithium nickel manganate, copper fluoride, cobalt fluoride, cobaltous fluoride, iron fluoride, ferrous fluoride, manganese fluoride, nickel fluoride, zinc fluoride, niobium fluoride, molybdenum chloride, iron chloride, magnetite, vanadium pentoxide, nickel sulfide, cobalt sulfide, silicon sulfide, tetraphosphorus heptasulfide, diphosphorus pentasulfide, copper oxide, strontium oxide, cobalt oxide, iron sesquioxide, manganese dioxide, molybdenum dioxide, molybdenum trioxide, lithium titanate, lithium vanadate, silicon-carbon composite material, silicon monoxide-carbon composite material, silicon monoxide, silicon dioxide, natural graphite, artificial graphite, graphene, carbon nanotube, carbon nanofiber.

5. The method of interface regulation of prelithiated electrodes according to claim 1, wherein, The contact is soaking and standing contact; the soaking and standing contact is a contact reaction under the condition of -40℃-200℃, and the time of the contact reaction is 1 second-72 hours; The drying temperature of the oven drying is -10℃-300℃.

6. A method for preparing an interface regulating liquid for the interface regulating method of the prelithiated electrode according to any one of claims 1 to 5, characterized in that, The preparation method of the interface regulation liquid comprises: Mixing solvent and metal salt in proportion to obtain a metal salt solution; Under an inert atmosphere, the metal salt solution is mixed uniformly by magnetic stirring at an ambient temperature of -10℃-100℃ to obtain an interface regulation liquid for a pre-lithiated electrode; The solvent comprises one or more of ether solvent, ester solvent, ketone solvent, hydrocarbon solvent, nitrile solvent or deionized water; The metal salt comprises one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium bisoxalate borate, lithium bisfluorosulfonimide, lithium bis-trifluoromethylsulfonimide, lithium perchlorate, lithium fluoride, lithium chloride; the concentration of the metal salt is 0.001g / mL-10g / mL; The pre-lithiated electrode is obtained by supplementing lithium to the electrode by a chemical pre-lithiation solution; the chemical pre-lithiation solution comprises one or more of lithium biphenyl-dimethyltetrahydrofuran solution, lithium biphenyl-tetrahydrofuran solution, tetramethyl lithium biphenyl-dimethyltetrahydrofuran solution, tetramethyl lithium biphenyl-tetrahydrofuran solution, lithium naphthalene-dimethyltetrahydrofuran solution, lithium naphthalene-tetrahydrofuran solution, liquid ammonia-lithium solution; The interface regulation liquid is used for modifying the pre-lithiated electrode, the metal salt in the interface regulation liquid reacts with the chemical pre-lithiation solution remaining on the surface of the pre-lithiated electrode, and a solid electrolyte layer containing inorganic lithium salt is generated on the surface of the pre-lithiated electrode; wherein the content of the inorganic lithium salt is 5%-90%.

7. The method of claim 6, wherein the interface-controlling liquid is prepared by, The solvent specifically includes one or more of methyl propyl ether, methyl butyl ether, methyl pentyl ether, ethyl propyl ether, ethyl butyl ether, ethyl pentyl ether, propyl butyl ether, propyl pentyl ether, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, ethyl tetrahydrofuran, diethyl tetrahydrofuran, phenyl tetrahydrofuran, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, diphenyl carbonate, dibutyl carbonate, butylene carbonate, methyl ethyl carbonate, fluoroethylene carbonate, trimethylene carbonate, chloroethylene carbonate, vinylene carbonate or deionized water; The interfacial regulation liquid further comprises a conductive additive; the conductive additive specifically includes one or more of carbon black, acetylene black, ketjen black, carbon nanotube, graphene, graphene oxide, carbon fiber, carbon quantum dot; The interfacial regulation liquid further comprises a binder; the binder specifically includes one or more of polyvinylidene fluoride, carboxymethyl cellulose, polytetrafluoroethylene, polyacrylic acid, butadiene styrene rubber, polyvinyl alcohol, polybutyl acrylate, polyacrylonitrile; The interfacial regulation liquid further comprises a functional filler; the functional filler specifically includes one or more of boron nitride, aluminum nitride, silicon nitride, silicon carbide, magnesium oxide, beryllium oxide, aluminum oxide, zinc oxide, silicon oxide, gold powder, silver powder, copper powder, nickel powder, aluminum powder.

8. The method of claim 6, wherein the interface-controlling liquid is prepared by mixing the liquid and the surfactant in a ratio of 1: 1 to 1:

10. The speed of the magnetic stirring is between 50 rpm and 2000 rpm, and the time of the magnetic stirring is between 1 second and 48 hours.

9. A lithium battery, characterized by The lithium battery comprises the interfacially regulated prelithiation electrode obtained by the interfacial regulation method of the prelithiation electrode according to any one of claims 1-5.

Images