WO2020125560A1 - 预嵌钾负极、制备方法和应用、钾基双离子电池及其制备方法和用电设备 - Google Patents

预嵌钾负极、制备方法和应用、钾基双离子电池及其制备方法和用电设备 Download PDF

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WO2020125560A1
WO2020125560A1 PCT/CN2019/125433 CN2019125433W WO2020125560A1 WO 2020125560 A1 WO2020125560 A1 WO 2020125560A1 CN 2019125433 W CN2019125433 W CN 2019125433W WO 2020125560 A1 WO2020125560 A1 WO 2020125560A1
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potassium
negative electrode
metal
metal foil
carbonate
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French (fr)
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唐永炳
高齐励
张苗
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Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Institute of Advanced Technology of CAS
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application belongs to the technical field of energy storage devices, and particularly relates to a pre-embedded potassium negative electrode, a preparation method and application, a potassium-based dual ion battery, a preparation method thereof, and electrical equipment.
  • Lithium-ion rechargeable secondary batteries are widely used due to their advantages of high energy density, long cycle life, and multiple uses.
  • the relationship between supply and demand The imbalance has made people realize that it is imperative to develop new rechargeable battery systems to avoid excessive dependence on lithium ion batteries, such as sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), aluminum Ion batteries (AIBs) and dual ion batteries (DIBs), etc.
  • SIBs sodium ion batteries
  • PIBs potassium ion batteries
  • MIBs magnesium ion batteries
  • AIBs aluminum Ion batteries
  • DIBs dual ion batteries
  • the potassium-based dual-ion battery combines the respective advantages of potassium-ion batteries and dual-ion batteries. It not only makes full use of low-cost potassium ions as an energy storage medium, but also uses anions and cations to embed and deintercalate on positive and negative materials, respectively. Flexible working mode.
  • some potassium-based dual-ion batteries use graphite electrodes as the positive and negative electrodes.
  • the Chinese patent with publication number CN108630939A uses graphite electrodes as the positive and negative electrodes to avoid the use of transition metal compounds to reduce costs.
  • due to potassium ions The relatively large size of carbon dioxide leads to the limitation of the carbon material’s potassium storage capacity, and its reversible charge and discharge capacity is too low to meet the needs of conventional devices.
  • the research and development of metal anode materials increased the capacity of the entire battery; at the same time, the metal anode as a current collector can further improve the energy density of the device while effectively improving the safety of lithium-ion batteries. low.
  • the literature of Advanced Materials (Advanced Materials, 2017, 29(19): 1700519) was the first to report the use of metal foil as the anode of potassium-based dual ion batteries.
  • the metal foil can integrate the negative electrode and the current collector.
  • the alloying reaction between potassium and the metal negative electrode corresponds to a higher theoretical specific capacity, which effectively improves the energy density of the battery system and reduces the production cost.
  • the metal foil used as the negative electrode sheet has the following problems, which greatly reduces the cycle stability: (1) During the alloying of potassium ions and metals, the negative electrode material is repeatedly deintercalated with potassium, its structure is destroyed and powdered, and the battery capacity is reduced. ; (2) A new SEI film formed by the continuous reaction of the powdered metal foil and the electrolyte at the new interface, the electrolyte and the potassium salt in it are continuously consumed, and the increasing thickness of the SEI film causes the interface impedance to increase, Coulomb The efficiency decreases and the battery capacity decreases.
  • the first object of the present application is to provide a pre-embedded potassium negative electrode, which has good structural integrity or stability, helps to improve the Coulomb efficiency, thereby improving the stability of the battery and the charge and discharge performance at high rate current, which can overcome The above problems or partial solutions to the above problems.
  • the second object of the present application is to provide a method for preparing a pre-embedded potassium negative electrode.
  • This method can form a SEI film layer and/or a potassium-metal alloy layer on the surface of a metal foil to improve the structural integrity or stability of the negative electrode. It helps to improve the Coulomb efficiency, thereby improving the stability of the battery and the charge and discharge performance under high rate current, which can overcome the above problems or partially solve the above problems.
  • the third object of the present application is to provide an application of the pre-embedded potassium negative electrode or the pre-embedded potassium negative electrode obtained by the preparation method of the pre-embedded potassium negative electrode in a potassium-based dual ion battery.
  • the fourth object of the present application is to provide a potassium-based dual ion battery.
  • the fifth object of the present application is to provide a method for preparing a potassium-based dual ion battery.
  • the application of the pre-embedded potassium negative electrode of the present application in a potassium-based dual-ion battery can provide the potassium-based dual-ion battery with good cycle stability, high Coulomb efficiency, and excellent charge-discharge performance under high-rate current conditions.
  • the sixth object of the present application is to provide an electric device including the above-mentioned potassium-based dual ion battery.
  • the present application provides a pre-embedded potassium negative electrode, the negative electrode comprising:
  • a metal foil and a potassium-metal alloy layer formed on the surface of the metal foil Or, a metal foil and a potassium-metal alloy layer formed on the surface of the metal foil;
  • a metal foil a potassium-metal alloy layer disposed opposite to the metal foil, and a SEI film layer disposed between the metal foil and the potassium-metal alloy layer;
  • a metal foil a SEI film layer disposed opposite to the metal foil, and a potassium-metal alloy layer disposed between the metal foil and the SEI film layer.
  • the metal foil is a metal, alloy or metal composite material capable of alloying/dealloying with potassium ions
  • the metal foil serves as both the negative electrode active material and the negative electrode current collector
  • the metal is at least one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the alloy is an alloy containing at least any one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the metal composite material is a composite material containing at least any one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the metal foil is tin, tin alloy or tin-containing composite material.
  • the present application provides a method for preparing a pre-embedded potassium anode, providing a half-cell, and charging and/or discharging the half-cell;
  • the negative electrode of the half-cell is a metal foil
  • the electrolyte of the half-cell is a potassium salt solution containing additives
  • the counter electrode of the half-cell is a material capable of providing a potassium source, and a potential difference is generated between the counter electrode and the negative electrode to realize the transmission of potassium ions.
  • the metal foil is a metal, alloy or metal composite material capable of alloying/dealloying with potassium ions
  • the metal foil serves as both the negative electrode active material and the negative electrode current collector
  • the metal is at least one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the alloy is an alloy containing at least any one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the metal composite material is a composite material containing at least any one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth;
  • the metal foil is tin, tin alloy or tin-containing composite material.
  • the electrolyte includes potassium salts, additives, and non-aqueous solvents
  • the potassium salt includes potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluorooxalate borate, potassium pyrophosphate, potassium dodecylbenzenesulfonate, deca Potassium dialkyl sulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, potassium iodate, potassium iodide, potassium silicate, potassium lignosulfonate, Potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, potassium trifluoromethanesulfonimide or potassium trifluoromethanesulfonate At least one of
  • the concentration range of potassium salt in the electrolyte is 0.1 ⁇ 10mol/L
  • the additives include at least one of film-forming additives, stabilizers, additives for improving high and low temperature performance, conductive additives or flame retardant additives;
  • Additives include fluoroethylene carbonate, vinylene carbonate, ethylene ethylene carbonate, trifluoropropylene carbonate, 1,3-propane sultone, vinyl sulfate, propylene sulfate, ethylene sulfate, disulfide Methyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, dimethyl sulfoxide, anisole, acetamide, diazabenzene, m-diazabenzene, 12 -Crown-4, 4-fluoroanisole, fluorinated chain ether, difluoromethyl vinyl carbonate, trifluoromethyl vinyl carbonate, chloroethylene carbonate, brominated vinyl carbonate, tris Fluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoxyethane, phosphate, phosphite, phosphazene, ethanolamine, carbodimethylamine,
  • the mass fraction of additives in the electrolyte is 0.1-20%;
  • the non-aqueous solvent includes propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate, methyl acetate, N,N-dimethylacetamide, fluorocarbonic acid Vinyl ester, methyl propionate, ethyl propionate, ethyl acetate, ⁇ -butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3- Dioxolane, dimethoxymethane, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, dimethyl ether, vinyl sulfite, propylene sulfite, disulfite At least one of methyl ester, diethyl sulfite or crown ether, preferably a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl
  • Materials that can provide a source of potassium include potassium-containing compounds or potassium metal foils.
  • the technical solution adopted in the embodiments of the present application further includes: the concentration range of the potassium salt in the electrolyte is 0.5 to 1.5 mol/L.
  • the technical solutions adopted in the embodiments of the present application further include: the mass fraction of the additives in the electrolyte is 2-10%.
  • the technical solutions adopted in the embodiments of the present application further include: charging and/or discharging the half-cells including: connecting the half-cells to a charge-discharge tester for constant current discharge, using the set discharge capacity as the standard to achieve the set After the fixed discharge capacity, stop the test and disassemble to get the pre-embedded potassium negative electrode;
  • the discharge current is 0.1 ⁇ 5C
  • the set discharge capacity is 0.02 ⁇ 0.5mAh
  • the half-cell further includes a separator including one or more of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, glass fiber paper, or a porous ceramic separator.
  • a separator including one or more of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, glass fiber paper, or a porous ceramic separator.
  • the present application provides an application of the above-mentioned pre-embedded potassium negative electrode or the pre-embedded potassium negative electrode obtained by the above pre-embedded potassium negative electrode preparation method in a potassium-based dual ion battery.
  • the present application provides a potassium-based dual ion battery, including a negative electrode, a positive electrode, a separator between the positive and negative electrodes, and an electrolyte;
  • the negative electrode is the above-mentioned pre-embedded potassium negative electrode or the pre-embedded potassium negative electrode obtained by the preparation method of the above pre-embedded potassium negative electrode;
  • the positive electrode includes a positive electrode current collector and a positive electrode material, the positive electrode material includes a positive electrode material active material, and the positive electrode material active material is a graphite-based carbon material that can reversibly insert and extract anions in the electrolyte;
  • the active material of the positive electrode material is expanded graphite.
  • the present application provides a method for preparing a potassium-based dual ion battery, which assembles a negative electrode, an electrolyte, a separator, and a positive electrode to obtain a potassium-based dual ion battery;
  • the method includes the following steps:
  • step (b) Assemble the pre-embedded potassium negative electrode obtained in step (a) with an electrolyte, a separator, and a positive electrode to obtain a potassium-based dual ion battery.
  • the present application provides an electric device including the above-mentioned potassium-based dual-ion battery or the potassium-based dual-ion battery obtained by the method for preparing the above-mentioned potassium-based dual-ion battery.
  • the pre-embedded potassium negative electrode provided in this application is provided with a SEI film layer and/or a potassium-metal alloy layer on the surface of the metal foil, that is, pre-embedded potassium on the metal negative electrode to protect the metal negative electrode, and can also achieve uniform potassium Ion diffusion effectively avoids severe volume expansion and electrode structure damage caused by uneven alloying of potassium ions and metal anodes during battery cycling.
  • the advance pre-embedding of potassium ions also effectively reduces the irreversible consumption of potassium ions during the formation of the negative electrode SEI film, thereby ensuring the cycling stability and high specific capacity of the battery.
  • the preparation method of the present application forms a stable SEI film layer and/or a potassium-metal alloy layer on the surface of the metal foil by pre-embedding potassium, which protects the material structure and introduces more potassium ions; it can improve the negative electrode
  • the structural integrity or stability of the battery helps to improve the Coulomb efficiency, thereby improving the stability of the battery and the charge-discharge performance at high rate current, thereby overcoming the poor cycle stability and high rate current conditions of the existing potassium dual ion battery Problems such as lower charge-discharge performance significantly decreased.
  • the preparation method is simple and easy to implement, convenient to control, safe in process, low in cost, and easy to realize large-scale industrial production.
  • a SEI film layer and/or a potassium-metal alloy layer are formed on the surface of the metal foil, and an appropriate amount of potassium-metal alloy layer not only ensures the integrity of the metal anode structure but also changes the internal stress of the metal foil; the SEI film layer compares to the double
  • the SEI film continuously generated by the ion battery's own reaction is more uniform and stable, which can protect the structure of the metal negative electrode and reduce the rate of new SEI film generation; the advance pre-embedding of potassium ions eases the dissolution of potassium salt in the electrolyte of the dual ion battery Limitations, while avoiding the capacity attenuation caused by excessive consumption of potassium and potassium during the repeated formation of the SEI film; a stable SEI film is conducive to the rapid transmission of potassium ions from the electrolyte to the metal anode material, which can effectively improve the first cycle of the dual ion battery Coulomb efficiency.
  • the preparation method of the potassium-based dual ion battery or the potassium-based dual ion battery provided by the present application has the advantages of low cost, stable structure, high coulombic efficiency, good cycle performance and high rate current due to the use of the above-mentioned pre-embedded potassium negative electrode Advantages such as excellent charge and discharge performance under conditions.
  • Example 7 is a cycle performance graph of a potassium-based dual ion battery provided in Example 7 of the present invention.
  • Example 12 is a rate performance diagram of the potassium-based dual ion battery provided in Example 12 of the present application.
  • Example 3 is a charge-discharge curve diagram of the potassium-based dual ion battery provided in Example 12 of the present application.
  • a-b represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the forms of the "lower limit” and the upper limit disclosed in the “range” of this application may be one or more lower limits and one or more upper limits, respectively.
  • each reaction or operation step may be performed sequentially or not.
  • the methods herein are performed sequentially.
  • pre-embedded potassium there are differences between pre-embedded potassium and pre-embedded lithium.
  • the differences between the two are as follows: (1) The purpose of the two is different. The step of pre-embedded lithium in the preparation of the capacitor is to provide a sufficient amount of lithium ions for the normal operation of the capacitor. The amount of embedding is sufficient; and one of the purposes of this application is to embed an appropriate amount of potassium into the metal foil and form a uniform SEI film on the surface to improve the stability of the dual-ion battery; (2) the two lithium/potassium sources are different, The pre-intercalated lithium only uses the lithium salt in the electrolyte, which needs to be repeatedly charged and discharged up to 100 times, which takes too long.
  • One of the purposes of this application is to effectively use the potential difference between the potassium foil and the metal foil, and discharge with a small current
  • the metal foil can be modified at one time; (3)
  • the ion radius of potassium ions is larger than that of lithium ions, and the insertion of potassium ions in the electrode material is more difficult, and it is difficult to achieve the surface modification of the negative electrode with uniform potassium insertion; (4) Due to the different purposes of the two, this application has special requirements for the depth and uniformity of the potassium embedding reaction of the metal foil. Therefore, this application is quite different from the research on lithium pre-intercalation in lithium ion capacitors/batteries.
  • a pre-embedded potassium negative electrode is provided, the negative electrode including:
  • a metal foil and a potassium-metal alloy layer formed on the surface of the metal foil Or, a metal foil and a potassium-metal alloy layer formed on the surface of the metal foil;
  • a metal foil a potassium-metal alloy layer disposed opposite to the metal foil, and a SEI film layer disposed between the metal foil and the potassium-metal alloy layer;
  • a metal foil a SEI film layer disposed opposite to the metal foil, and a potassium-metal alloy layer disposed between the metal foil and the SEI film layer.
  • the present application provides a pre-embedded potassium negative electrode to improve the stability of the potassium-based dual ion battery and the charge-discharge performance under high rate current, thereby overcoming the existing potassium-based dual ion battery
  • the problem of poor cycle stability and significantly reduced charge and discharge performance under high rate current conditions provides a guarantee for the effective application of potassium dual-ion batteries.
  • the pre-embedded potassium negative electrode of the present application includes a metal foil and a SEI film layer and/or a potassium-metal alloy layer provided on the surface of the metal foil;
  • the metal foil is a metal, alloy or metal composite material capable of alloying/dealloying with potassium ions.
  • a uniform solid electrolyte layer (SEI film) and/or a potassium-metal alloy layer are formed on the surface of the metal anode by pre-embedding potassium to protect the metal anode of the potassium dual ion battery.
  • the metal foil negative electrode with uniformly modified SEI film layer and/or potassium-metal alloy layer on the surface can be used to achieve uniform potassium ion diffusion in potassium dual-ion batteries, effectively avoiding uneven alloying of potassium ions and metal anodes during battery cycling The resulting volume expansion is severe and the electrode structure is destroyed.
  • the advance pre-embedding of potassium ions also effectively reduces the irreversible consumption of potassium ions during the formation of the negative electrode SEI film, thereby ensuring the cycling stability and high specific capacity of the battery.
  • SEI membrane refers to the Solid Electrolyte Interface membrane, that is, the solid electrolyte membrane, which is formed during the first discharge of the secondary battery. It is the reaction between the electrode material and the electrolyte at the solid-liquid interface, thus forming a layer covering the electrode Passivation layer on the surface of the material.
  • the SEI membrane can stably exist in organic solvents, and can effectively prevent the passage of solvent molecules to avoid the destruction of the electrode material caused by the reaction of the solvent molecules with the electrode material; however, potassium ions can be freely inserted and extracted through the SEI membrane, without The battery's charge and discharge and cycle performance have an adverse effect.
  • SEI consumes potassium ions during the formation process, producing irreversible charge and discharge capacity, which reduces the charge and discharge efficiency of the electrode material.
  • the change of the solid-liquid interface causes the SEI to continuously increase, and the consumption of the electrolyte will cause the acceleration of the capacity.
  • An excessively thick SEI film increases the potassium ion transmission impedance at the interface and reduces the dynamics of the entire system.
  • “Potassium-metal alloy layer” refers to the alloy of metal material and potassium formed by the alloying reaction between the potassium-containing material and the metal foil, which can not only ensure the structural integrity of the metal anode, but also change the interior of the metal foil stress.
  • SEI film layer and/or potassium-metal alloy layer means that the SEI film layer is formed on the surface of the metal foil, or the potassium-metal alloy layer is formed on the surface of the metal foil, or the SEI is formed on the surface of the metal foil Film layer and potassium-metal alloy layer.
  • Metal, alloy or metal composite material capable of alloying/dealloying with potassium ions means a metal capable of alloying/dealloying with potassium ions, alloying/dealloying with potassium ions
  • Alloy refers to a substance with metallic properties synthesized by two or more metals and metals or non-metals through a certain method.
  • Metal composite material refers to a metal-based composite conductive material formed by combining metals with other non-metallic materials.
  • Typical but non-limiting metal composite materials include graphene-metal composite materials, carbon fiber-metal composite materials or ceramic-metal composite materials.
  • metal foil material is not limited in this application, as long as the purpose of this application is not limited.
  • the metal foil is a metal, alloy or metal composite material capable of alloying/dealloying with potassium ions;
  • the metal foil serves as both the negative electrode active material and the negative electrode current collector.
  • the metal foil that can be alloyed/dealloyed with potassium ions is used as the negative electrode active material and negative electrode current collector at the same time, which plays a dual role of conductivity and reaction, so that the negative electrode active material and negative electrode current collector of the conventional potassium ion battery negative electrode
  • the two elements are omitted as one type.
  • the negative electrode in the prior art it usually includes a current collector and a reactive material for reaction, which saves the volume and weight of a component and simplifies the device manufacturing process, and It is beneficial to increase the proportion of active materials, can obtain higher energy density, and further increase the energy density and specific capacity of the battery; and the negative electrode material is rich in content and cheaper, which effectively reduces the production cost of the battery.
  • the negative electrode metal foil is a related metal, alloy, or metal composite material that can form an alloy with potassium.
  • the metal is at least one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony or bismuth, preferably sodium, tin, lithium, zinc, lead or At least one of germanium;
  • the alloy is an alloy containing at least any one of sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony, or bismuth, preferably at least sodium, tin, lithium,
  • the metal composite material is a composite material containing at least sodium, tin, lithium, zinc, lead, germanium, copper, iron, nickel, titanium, manganese, antimony, or bismuth, preferably at least sodium, tin , Lithium, zinc, lead or germanium composite materials; the above composite materials are typically but not limited to tin/graphene composite foil, sodium/graphene composite foil or zinc/graphene composite foil, etc. .
  • the metal foil is tin, tin alloy or tin-containing composite material
  • the metal foil is tin foil.
  • the form of the above-mentioned metal material is preferably a foil
  • the form of the prepared pre-embedded potassium negative electrode is preferably a sheet.
  • a method for preparing a pre-embedded potassium negative electrode is provided, a half battery is provided, and the half battery is charged and/or discharged;
  • the negative electrode of the half-cell is a metal foil
  • the electrolyte of the half-cell is a potassium salt solution containing additives
  • the counter electrode of the half-cell is a material that can provide a potassium source, and a high potential difference is generated between the counter electrode and the negative electrode to realize the transmission of potassium ions.
  • a method is proposed to improve the stability of the potassium dual ion battery and the charge and discharge performance under high rate current by pre-embedding potassium, to overcome the existing potassium dual ion battery.
  • the problem of poor cycle stability and significantly reduced charge and discharge performance under high rate current conditions provides a guarantee for the effective application of potassium dual-ion batteries.
  • the pre-embedded potassium anode prepared by this method includes a metal foil and a SEI film layer and/or a potassium-metal alloy layer provided on the surface of the metal foil, and has the following characteristics: (1) an appropriate amount of potassium-metal alloy The layer not only ensures the integrity of the metal anode structure but also changes the internal stress of the metal foil; (2) The SEI film generated by the small current pre-discharge is more uniform and stable than the SEI film continuously generated by the dual-ion battery itself, and can be protected The structure of the metal negative electrode reduces the rate of new SEI film formation; (3) The pre-embedding of potassium ions in advance also eases the dissolution limitation of potassium salts in the electrolyte of the dual-ion battery, and avoids the potassium salts during the repeated formation of SEI films The capacity attenuation caused by excessive potassium consumption; (4) The stable SEI membrane is conducive to the rapid transmission of potassium ions from the electrolyte to the metal anode material, which can effectively improve the first-cycle
  • the above method is simple to operate, easy to implement, has good controllability, low cost, and is easy to popularize and apply.
  • potassium source is a material that can provide a potassium source, which refers to a material containing potassium, and the potassium in the material generates a high potential difference with the negative electrode metal foil during the charging or discharging of the half-cell to achieve the effective potassium ion
  • the transmission further forms an SEI film layer and/or a potassium-metal alloy layer on the surface of the negative electrode metal foil.
  • the electrolyte includes potassium salts, additives, and non-aqueous solvents; the additives in the electrolyte can be used to improve the stability and uniformity of the SEI membrane.
  • the present application has no specific limitation on the specific type of potassium salt in the half-cell electrolyte, and potassium salts commonly used in the art may be used as long as the purpose of the present application is not limited.
  • the potassium salt includes but is not limited to potassium hexafluorophosphate, potassium chloride, potassium fluoride, potassium sulfate, potassium carbonate, potassium phosphate, potassium nitrate, potassium difluorooxalate borate, potassium pyrophosphate, dodecyl Potassium benzenesulfonate, potassium dodecyl sulfate, tripotassium citrate, potassium metaborate, potassium borate, potassium molybdate, potassium tungstate, potassium bromide, potassium nitrite, potassium iodate, potassium iodide, potassium silicate, Potassium lignosulfonate, potassium oxalate, potassium aluminate, potassium methanesulfonate, potassium acetate, potassium dichromate, potassium hexafluoroarsenate, potassium tetrafluoroborate, potassium perchlorate, potassium trifluoromethanesulfonimide or One or at least two of potassium trifluorome
  • the potassium salt is potassium hexafluorophosphate.
  • the concentration range of the potassium salt in the electrolyte is 0.1 to 10 mol/L, preferably 0.5 to 1.5 mol/L; the concentration of the above potassium salt is typically but not limited to 0.1 mol/L, 0.5 mol/L, 1 mol /L, 1.5mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L, 6mol/L, 7mol/L, 8mol/L, 9mol/L or 10mol/L.
  • the present application has no special restrictions on the specific types of additives in the electrolyte of the half-cell, as long as the stability and uniformity of the SEI film can be improved, and the purpose of the present application is not limited.
  • the additives include at least one of film-forming additives, stabilizers, additives for improving high and low temperature performance, conductive additives or flame retardant additives;
  • the additives include fluoroethylene carbonate, vinylene carbonate, ethylene ethylene carbonate, trifluoropropylene carbonate, 1,3-propane sultone, vinyl sulfate, propylene sulfate, ethylene sulfate Ester, dimethyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, dimethyl sulfoxide, anisole, acetamide, diazabenzene, m-diaza Benzene, 12-crown-4, 4-fluoroanisole, fluorochain ether, difluoromethylvinyl carbonate, trifluoromethylvinyl carbonate, chloroethylene carbonate, brominated ethylene carbonate Ester, trifluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoxyethane, phosphate, phosphite, phosphazene, ethanolamine, carbodi
  • the additive is one or at least two of fluoroethylene carbonate (FEC), vinylene carbonate (VC), ethylene ethylene carbonate (VEC), or trifluoropropylene carbonate (TFPC).
  • FEC fluoroethylene carbonate
  • VC vinylene carbonate
  • VEC ethylene ethylene carbonate
  • TFPC trifluoropropylene carbonate
  • the mass fraction of the additive in the electrolyte is 0.1-20%, preferably 2-10%; the mass fraction of the above additive is typically but not limited to 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%.
  • the stability and uniformity of high SEI films can be adjusted.
  • the mass fraction of additives is 0.1-20%, the thickness of SEI is reasonable, the stability and uniformity are good, and it will not affect the negative electrode. Chemical properties.
  • non-aqueous solvent in the half-cell electrolyte has no particular limitation on the specific type of non-aqueous solvent in the half-cell electrolyte, and a non-aqueous solvent commonly used in the art may be used as long as the purpose of the present application is not limited.
  • the non-aqueous solvent includes propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl formate (MF), methyl acetate (MA), N,N-dimethylacetamide (DMA), fluoroethylene carbonate (FEC), methyl propionate (MP), ethyl propionate (EP), acetic acid Ethyl ester (EA), ⁇ -butyrolactone (GBL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), 1,3-dioxolane (DOL), 4-methyl-1,3 -Dioxolane (4MeDOL), dimethoxymethane (DMM), 1,2-dimethoxypropane (DMP), triethylene glycol dimethyl ether (DG), dimethyl sulfone (MSM), dimethicone Dimethyl
  • PC prop
  • Typical but non-limiting solvents are propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate, methyl acetate, N,N-dimethylacetamide, Fluoroethylene carbonate, methyl propionate, ethyl propionate, ethyl acetate, ⁇ -butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1 ,3-dioxolane, dimethoxymethane, 1,2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, dimethyl ether, vinyl sulfite, propylene sulfite, Dimethyl sulfite, diethyl sulfite, crown ether (12-crown-4), combination of propylene carbonate and ethylene carbonate, combination of ethylene carbonate, dimethyl carbon
  • the non-aqueous solvent is a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.
  • the potassium source includes a potassium-containing compound or potassium metal foil
  • the potassium source is potassium metal foil.
  • the potassium source is included in the half-cell, and the potassium source of the half-cell can generate a high potential difference with the negative electrode to realize the effective transmission of potassium ions.
  • potassium-containing compound refers to a substance composed of potassium and one or more elements.
  • the potassium-containing compound may be potassium sulfide potassium fluoride, potassium oxalate, potassium cobaltate, or the like.
  • the potassium source is preferably flat potassium metal foil.
  • charging and/or discharging the half-cell includes: connecting the half-cell to a charge-discharge tester for constant current discharge, using the set discharge capacity as the standard, to reach the set After discharging the electricity, stop the test and disassemble to get the pre-embedded potassium negative electrode;
  • the discharge current is 0.1 to 5C;
  • the discharge power is 0.02 ⁇ 0.5mAh
  • the half-cell further includes a separator, and the separator includes one or more of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, a glass fiber paper, or a porous ceramic separator.
  • the separator includes one or more of a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, a glass fiber paper, or a porous ceramic separator.
  • the pre-embedded potassium modified metal negative electrode used in this application is to place potassium metal in the negative electrode, the metal foil material is used to prepare the potassium ion half-cell for the counter electrode, and the half-cell is placed on the charge and discharge tester, constant current Discharge and control the amount of discharge to obtain a metal foil with the surface uniformly covered with the SEI film layer and uniformly pre-embedded potassium.
  • the modified metal foil-pre-embedded potassium negative electrode is used as the negative electrode of the potassium double ion battery.
  • Mainly has the following characteristics: (1) A proper amount of potassium-metal alloy layer not only guarantees the integrity of the metal anode structure but also changes the internal stress of the metal foil; (2) The SEI film generated by small current pre-discharge is compared with the dual ion battery itself The SEI film generated by the reaction is more uniform and more stable, which can protect the structure of the metal negative electrode and reduce the rate of new SEI film generation; (3) The pre-embedded potassium ion also eases the potassium salt in the electrolyte of the dual ion battery Dissolution limitation, while avoiding the capacity attenuation caused by excessive consumption of potassium and potassium during the repeated formation of the SEI film; (4) The stable SEI film is conducive to the rapid transmission of potassium ions from the electrolyte to the metal anode material, which can effectively improve the double ion The battery's first lap Coulomb efficiency.
  • the negative electrode metal foil material is required to be able to form a potassium-metal alloy with potassium to achieve pre-embedding of potassium; the pre-embedded potassium half-cell potassium source and the negative electrode generate a high potential difference to achieve potassium ion Effective transmission; additives in the electrolyte are used to improve the stability and uniformity of the SEI membrane. In addition, it also plays an important role in regulating the discharge current and discharge capacity of pre-embedded potassium half-cells.
  • the discharge current of the pre-embedded potassium half-cell is used to control the grain size of the potassium-metal alloy and optimize the internal stress of the metal foil; the discharge power of the pre-embedded potassium half-cell is used to control the thickness and stability of the potassium-metal alloy layer can be a conductive carbon material 3.
  • the conductive metal material may also be a conductive polymer.
  • the discharge current of the pre-embedded potassium half-cell is used to control the grain size of the potassium-metal alloy and optimize the internal stress of the metal foil.
  • the discharge current of the pre-embedded potassium process is 0.1 to 5C; typical but not
  • the restrictive discharge current may be, for example, 0.1C, 0.2C, 0.5C, 0.6C, 0.9C, 1C, 1.5C, 2C, 2.5C, 3C, 3.5C, 4C, 4.5C, or 5C.
  • the discharge power of the pre-embedded potassium half-cell is used to control the thickness and stability of the potassium-metal alloy layer, which can be a conductive carbon material, a conductive metal material or a conductive polymer to control the pre-embedded potassium process
  • the discharge capacity is 0.02-0.5mAh; typical but non-limiting discharge capacity can be 0.02mAh, 0.05mAh, 0.08mAh, 0.1mAh, 0.15mAh, 0.2mAh, 0.25mAh, 0.3mAh, 0.4mAh or 0.5mAh, for example.
  • preparation method of the pre-embedded potassium anode includes the following steps:
  • porous polymer film or inorganic porous film or organic/inorganic composite diaphragm of the required size is used as the diaphragm, and it is die-cut to the required size for standby;
  • an application of the pre-embedded potassium anode or the pre-embedded potassium anode obtained by the method for preparing the pre-embedded potassium anode in a potassium-based dual ion battery is provided.
  • a potassium-based dual ion battery including a negative electrode, a positive electrode, a separator between the positive and negative electrodes, and an electrolyte;
  • the negative electrode is the pre-embedded potassium negative electrode described above or the pre-embedded potassium negative electrode obtained by the preparation method of the pre-embedded potassium negative electrode described above;
  • the positive electrode includes a positive electrode current collector and a positive electrode material
  • the positive electrode material includes a positive electrode material active material
  • the positive electrode material active material is a graphite-based carbon material that can reversibly insert and release anions in the electrolyte
  • the active material of the positive electrode material is expanded graphite.
  • the potassium-based dual-ion battery is a simple, controllable pre-embedded potassium-modified dual-ion battery, which improves the stability of the potassium dual-ion battery and the charging and discharging performance under high rate current, and overcomes the existing The problem of poor cycle stability in potassium dual-ion batteries and a significant decrease in charge-discharge performance under high-rate current conditions.
  • the core of the potassium-based dual-ion battery includes the use of the above-mentioned pre-embedded potassium negative electrode.
  • the potassium-based dual-ion battery also includes other components or parts of the existing dual-ion battery.
  • the positive electrode, electrolyte, separator, and casing matching the potassium-embedded negative electrode are not particularly limited in this application; in addition, the preparation method of the potassium-based dual ion battery can also be prepared by using the existing preparation method. This application does not specifically limit this.
  • the positive electrode of the dual ion battery includes a positive electrode current collector and a positive electrode material.
  • the positive electrode material includes an active material of the positive electrode material.
  • the active material of the positive electrode material is graphite that can reversibly intercalate and deintercalate anions in the electrolyte. Carbon-like materials;
  • the positive active material is expanded graphite
  • the cathode current collector is any metal of aluminum, copper, tin, zinc, lead, iron, nickel, gold, magnesium, zinc, or germanium; or, the cathode current collector is at least aluminum, copper , Tin, zinc, lead, iron, nickel, gold, magnesium, zinc or germanium; or, the positive electrode current collector is at least aluminum, copper, tin, zinc, lead, iron, nickel, gold , Magnesium, zinc or germanium; any metal composite; preferably, carbon-coated aluminum foil;
  • the conductive agent includes one or at least two of conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, carbon fiber or graphene;
  • the binder includes one or at least two of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber, and polyolefin binder;
  • the positive electrode material includes 70 to 95 wt% of the positive electrode material active material, 2 to 20 wt% of the conductive agent, and 3 to 10 wt% of the binder;
  • the separator includes one or more of porous polypropylene film, porous polyethylene film, porous composite polymer film, glass fiber paper, and porous ceramic separator.
  • the positive electrode and the negative electrode are connected in such a way that the positive electrode and the negative electrode are connected by a charging and discharging device after being assembled into a half-cell.
  • a method for preparing the potassium-based dual ion battery is provided.
  • the negative electrode, the electrolyte, the separator, and the positive electrode are assembled to obtain a potassium-based dual ion battery.
  • the method includes the following steps:
  • step (b) Assemble the pre-embedded potassium negative electrode obtained in step (a) with an electrolyte, a separator, and a positive electrode to obtain a potassium-based dual ion battery.
  • the above-mentioned preparation method of the potassium-based dual ion battery that is, the method of improving the performance of the potassium-based dual ion battery by pre-embedding potassium, mainly includes two stages:
  • Phase one prepare potassium-metal foil half-cell battery, connect the potassium ion half-cell to the charge and discharge tester for constant current discharge, take the set discharge amount as the standard, disassemble the battery after the test is stopped and get the pretreatment Metal foil, namely pre-embedded potassium anode.
  • Stage 2 The disassembled metal foil is used as the negative electrode of the dual-ion battery to reassemble into a modified potassium-based dual-ion battery.
  • the potassium half-cell electrolyte includes potassium salts, electrolyte additives, and non-aqueous solvents.
  • the potassium-based dual-ion battery electrolyte includes potassium salts and non-aqueous solvents.
  • the potassium salt and non-aqueous solvent in the electrolyte of the potassium-based dual ion battery can be referred to the introduction of the potassium salt and the non-aqueous solvent in the electrolyte of the half-cell above, and the same or similar potassium salt and electrolyte can be used for both .
  • the electrolyte of the dual ion battery includes a liquid electrolyte, a gel electrolyte, or a solid electrolyte.
  • the way to connect the positive electrode and the negative electrode is to assemble the half-cell and connect the positive electrode and the negative electrode through a charging and discharging device.
  • the preparation method of the potassium-based dual ion battery includes the following steps:
  • Phase one prepare potassium-metal foil half-cells, connect the potassium ion half-cells to a charge-discharge tester for constant current discharge, take the set discharge amount as the standard, disassemble the battery after the test is stopped to obtain the pretreated metal Foil.
  • Step 1 Preparation of metal foil: clean the metal foil of the negative electrode, cut and stamp it after drying to obtain the metal foil of the required size;
  • Step 2 Preparation of the separator: use a porous polymer film or an inorganic porous film or an organic/inorganic composite separator of the required size as the separator, and punch it into the required size;
  • Step 3 Preparation of potassium foil: rolling and flattening the potassium metal and cutting it to the required size, which is slightly larger than the size of the metal foil;
  • Step 4 Prepare half-cell electrolyte: dissolve the potassium salt electrolyte and corresponding additives in a non-aqueous solvent, and thoroughly mix to obtain the electrolyte;
  • Step 5 Assemble the potassium foil obtained in Step 3, the electrolyte obtained in Step 4, the separator obtained in Step 2, and the metal foil obtained in Step 1, to obtain a potassium ion half-cell;
  • Step 6 Connect the potassium ion half-cell obtained in step 5 to the charge and discharge tester, perform a single discharge with a constant appropriate amount of current, and use the set discharge amount as the standard. After reaching the set discharge amount, stop the test and remove battery;
  • Step 7 Disassemble the moderately discharged half-cell in Step 6, take out the potassium foil and keep it for reuse, and take out the metal foil completely to be the modified dual-ion battery anode material-pre-embedded potassium anode.
  • Stage 2 The disassembled metal foil is used as the negative electrode of the dual-ion battery to reassemble into a modified potassium-based dual-ion battery.
  • Step 8 Preparing the positive electrode of the dual ion battery: first weigh the appropriate positive electrode active material, binder and conductive agent according to a certain ratio, after grinding evenly, add an appropriate amount of solvent, and fully mix into a uniform slurry to make a positive electrode active material layer; Using a metal, metal alloy or metal composite conductive material as the positive electrode current collector, uniformly coat the positive electrode active material layer on the surface of the positive electrode current collector, place it in a vacuum drying box at a certain temperature for drying, and wait for the positive electrode active material After the layer is completely dried, it is punched into a positive electrode of the required size.
  • Step 9 Prepare the electrolyte of the dual-ion battery: dissolve the potassium salt electrolyte in a non-aqueous solvent and mix it thoroughly to obtain the electrolyte;
  • Step 10 Assemble the modified metal foil obtained in Step 7, the electrolyte obtained in Step 9, the separator obtained in Step 2 and the positive electrode obtained in Step 8 to obtain a potassium-based dual ion battery.
  • an electrical device including the above-mentioned potassium-based dual-ion battery or the potassium-based dual-ion battery obtained by the method for preparing the above-mentioned potassium-based dual-ion battery.
  • the electrical equipment includes the above-mentioned potassium-based dual-ion battery, so it has at least the same advantages as the potassium-based dual-ion battery, has the advantages of low cost, high energy density and good cycle stability.
  • the electrical equipment is charged and discharged at the same When used in current and the same environment, the service life is longer.
  • the above electrical equipment includes, but is not limited to, electronic devices, power tools, or electric vehicles.
  • the electronic device is an electronic device that performs various functions (for example, playing music) using the above-mentioned potassium-based dual ion battery as an operation power source.
  • the electric tool is an electric tool using the above-mentioned potassium-based dual ion battery as a driving power moving part (for example, a drill).
  • Electric vehicles are electric vehicles (including electric bicycles and electric vehicles) that rely on the above potassium-based dual-ion battery as a driving power source, and may be vehicles (including hybrid vehicles) equipped with other driving sources in addition to the above energy storage devices .
  • a preparation method of pre-embedded potassium anode includes the following steps:
  • step (6) Connect the potassium ion half-cell obtained in step (5) to the charge-discharge tester, perform a discharge at a current of 0.2C, set the total discharge capacity to 0.02mAh, and then stop the test to remove the battery.
  • step (7) Disassemble the moderately discharged half-cell in step (6), take out the potassium foil and keep it for reuse, and take out the metal foil completely to be the modified dual-ion battery anode material-pre-embedded potassium anode.
  • a method for preparing a pre-embedded potassium negative electrode differs from Embodiment 1 only in that the pre-embedded potassium discharge power in step (6); the other steps and parameters are the same as in Embodiment 1.
  • the potassium-based dual ion battery including the pre-embedded potassium anode prepared in Examples 1-10 includes the following steps:
  • step (c) In an inert gas-protected glove box, the pre-embedded potassium negative electrode obtained in the above step (7), the separator obtained in the step (2), and the positive electrode obtained in the step (a) are closely stacked in sequence, and the step (b) is obtained by dropping The electrolyte completely wets the separator, and then encapsulates the above into a button-type case to complete the assembly of the potassium-based dual ion battery.
  • Example 1 The potassium-based dual ion batteries provided in Example 1 and Examples 2-10 were subjected to electrochemical performance tests, including cycle number, capacity retention rate and Coulomb efficiency.
  • the test results are shown in Table 1.
  • the test method is as follows:
  • Cyclic charge and discharge are carried out on the CT2001C-001 blue battery cycle test system.
  • the standard capacity of the electrode is tested by charging and discharging at a 5C rate.
  • Rate charge and discharge It is also carried out on the blue battery cycle test system, and the charge and discharge at different rates (current density) are used to test the rate performance of the material. The conditions of charge and discharge depend on the needs of the experiment. The cycle steps and cycle charge and discharge the same.
  • Table 1 The main preparation conditions of the pre-embedded potassium anode of Examples 1-10 and the performance parameter table of potassium-based dual ion batteries
  • FIG. 1 shows the cycle performance chart of the potassium-based dual ion battery provided in Example 7 of the present application, that is, 2% FEC electrolyte additive is added during the pre-embedded potassium process, the pre-embedded potassium discharge current is 0.2C, and the discharge capacity is Cycling performance graph of 0.2mAh dual ion battery. It can be seen from the graph of constant current charge-discharge specific capacity and Coulomb efficiency in FIG. 1 that the potassium-based dual ion battery of the present application has high Coulomb efficiency and high specific capacity.
  • Examples 11-20 are the same as the preparation process and test process steps of the potassium-based dual ion battery modified with pre-embedded potassium in Example 1, except that the discharge current of the pre-embedded potassium half-cell is different.
  • the test results of Examples 11-20 are shown in Table 2.
  • Table 2 Main preparation conditions and performance parameters of potassium-based dual-ion batteries for the pre-embedded potassium anodes of Examples 11-20
  • FIG. 2 shows the rate performance diagram of the potassium-based dual ion battery provided in Example 12 of the present application, that is, 2% FEC electrolyte additive is added during the pre-embedded potassium process, the pre-embedded potassium discharge current is 0.5C, and the discharge capacity is Rate performance graph of 0.2mAh dual ion battery.
  • FIG. 3 shows a charge-discharge curve diagram of the potassium-based dual ion battery provided in Example 12 of the present application, that is, 2% FEC electrolyte additive is added during the pre-embedded potassium, the pre-embedded potassium discharge current is 0.5C, and the discharge power is 0.2 Charge and discharge curve diagram of mAh dual ion battery.
  • Examples 21-30 are the same as the preparation process and test process steps of the potassium-based dual ion battery modified with pre-embedded potassium in Example 1, except that the additive for the pre-embedded potassium half-cell is different.
  • the test results of Examples 21-30 are shown in Table 3.
  • Examples 31-34 are the same as the preparation process and test process steps of the potassium-based dual ion battery modified with pre-embedded potassium in Example 1, except that the negative active material of the pre-embedded potassium half-cell is different.
  • the test results of Examples 31-36 are shown in Table 4.
  • a preparation method of a pre-embedded potassium negative electrode is different from Example 1 in that the electrolyte of this comparative example does not contain a fluoroethylene carbonate additive.
  • the pre-embedded potassium negative electrode prepared in Comparative Example 1 was prepared into a potassium-based dual ion battery, and the preparation method was the same as that in Example 1.
  • the performance test of the potassium-based dual ion battery of Comparative Example 1 was carried out in the same manner as in Example 1. The test showed that the capacity retention rate of the battery of Comparative Example 1 after 300 cycles was 80% and the energy density was 81 mAh/g. Lower than Example 1. It can be seen that the addition of fluoroethylene carbonate additives is beneficial to the formation of a stable SEI film and improves the cycle stability of the dual ion battery.
  • a method for preparing a potassium-based dual ion battery differs from Example 1 in the negative electrode.
  • the negative electrode used in Comparative Example 2 is an existing negative electrode, that is, tin foil; the rest are the same as in Example 1.
  • the potassium-based dual-ion battery prepared in Comparative Example 2 was subjected to performance tests. After testing, the battery retention rate of the battery of Comparative Example 2 was 300% in a cycle of 74% and the energy density was 69 mAh/g. The above performances were lower than those in Example 1. . It can be seen that the tin foil after pre-embedded potassium is more stable than the untreated tin foil, and its internal structure is more advantageous, which can effectively buffer the volume change caused by de-embedded potassium.

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Abstract

预嵌钾负极、制备方法和应用、钾基双离子电池及其制备方法和用电设备，属于储能器件技术领域。预嵌钾负极，包括：金属箔和形成于金属箔表面上的SEI膜层；或，金属箔和形成于金属箔表面上的钾-金属合金层；或，金属箔，形成于金属箔表面上的钾-金属合金层和SEI膜层。通过预嵌钾的方式在金属负极表面生成均匀的SEI膜层和/或钾-金属合金层用以保护金属负极，能够实现均匀的钾离子扩散，有效避免电池循环过程中由于钾离子与金属负极的不均匀合金化引起的部分体积膨胀严重和电极结构破坏。此外，钾离子的提前预嵌也有效减少了负极SEI膜形成过程中的钾离子不可逆消耗，保证了电池的循环稳定性以及高比容量。

Description

预嵌钾负极、制备方法和应用、钾基双离子电池及其制备方法和用电设备 技术领域
本申请属于储能器件技术领域，特别涉及预嵌钾负极、制备方法和应用、钾基双离子电池及其制备方法和用电设备。
背景技术
锂离子可充电二次电池因其高能量密度、长循环寿命、可多次使用等优势得以广泛应用，但是随着锂资源不断的开发损耗以及人们对于便携式电池的需求的日益增长，供需关系的失衡让人们逐渐意识到研发新的可充电池系统以避免对锂离子电池的过分依赖势在必行，如钠离子电池(SIBs)、钾离子电池(PIBs)、镁离子电池(MIBs)、铝离子电池(AIBs)以及双离子电池(DIBs)等。
其中，钾基双离子电池结合了钾离子电池与双离子电池各自的优点，既充分利用了成本低廉的钾离子作为储能介质，又利用了阴阳离子分别在正负极材料上嵌入和脱嵌的灵活工作模式。现有技术中，钾基双离子电池有些采用石墨电极作为正极和负极，例如公开号为CN108630939A的中国专利，采用石墨电极作为正极和负极，避免过渡金属化合物的使用以降低成本，但是由于钾离子的尺寸较大，导致了碳材料储钾容量的局限，其可逆充放电容量过低，远远不能满足常规器件需求。
随后，金属负极材料的研发提升了全电池的容量；同时金属负极作为集流 体，可在进一步提高器件能量密度的同时有效提高锂离子电池的安全性，高效电池体系电池的比能量密度高、成本低。例如先进材料中文献(Advanced Materials,2017,29(19):1700519)最先报道了以金属箔材作为钾基双离子电池负极。首先，金属箔材可以将负极和集流体一体化，其次钾与金属负极发生的合金化反应对应着更高的理论比容量，这有效提高了电池体系的能量密度，降低了生产成本。但是金属箔材作为负极极片存在如下问题使其循环稳定性大打折扣：(1)钾离子与金属合金化过程中，负极材料反复脱嵌钾，其结构遭到破坏粉化并引起电池容量衰减；(2)粉化的金属箔材与电解液在新的界面不断反应形成的新的SEI膜，电解液以及其中的钾盐被不断消耗，同时不断增厚的SEI膜造成界面阻抗增加，库伦效率降低，电池容量衰减。
发明内容
本申请的第一目的在于提供一种预嵌钾负极，该负极的结构完整性或稳定性好，有助于提高库伦效率，从而提高电池的稳定性及高倍率电流下充放电性能，能够克服上述问题或者部分的解决上述问题。
本申请的第二目的在于提供一种预嵌钾负极的制备方法，该方法能够在金属箔材表面形成SEI膜层和/或钾-金属合金层，提高负极的结构完整性或稳定性，有助于提高库伦效率，从而提高电池的稳定性及高倍率电流下充放电性能，能够克服上述问题或者部分的解决上述问题。
本申请的第三目的在于提供一种预嵌钾负极或所述的预嵌钾负极的制备方法得到的预嵌钾负极在钾基双离子电池中的应用。
本申请的第四目的在于提供一种钾基双离子电池。
本申请的第五目的在于提供一种钾基双离子电池的制备方法。将本申请的预嵌钾负极应用在钾基双离子电池中，能够赋予钾基双离子电池循环稳定性好，库伦效率高，高倍率电流条件下充放电性能优异等特点。
本申请的第六目的在于提供一种用电设备，包括上述的钾基双离子电池。
为实现上述目的，本申请提供了如下技术方案为：
根据本申请的一个方面，本申请提供一种预嵌钾负极，所述负极包括：
金属箔和形成于金属箔表面上的SEI膜层；
或，金属箔和形成于金属箔表面上的钾-金属合金层；
或，金属箔，与所述金属箔相对设置的钾-金属合金层，以及设置于所述金属箔和钾-金属合金层之间的SEI膜层；
或，金属箔，与所述金属箔相对设置的SEI膜层，以及设置于所述金属箔和SEI膜层之间的钾-金属合金层。
本申请实施例采取的技术方案还包括：所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料；
所述金属箔同时作为负极活性材料和负极集流体；
所述金属为钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中的至少一种；
或，所述合金为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的合金；
或，所述金属复合材料为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的复合材料；
金属箔为锡、锡合金或含锡的复合材料。
根据本申请的另一个方面，本申请提供了一种预嵌钾负极的制备方法，提 供一半电池，对所述半电池进行充电和/或放电；
其中，所述半电池的负极为金属箔；
所述半电池的电解液为含有添加剂的钾盐溶液；
所述半电池的对电极为能够提供钾源的材料，对电极与负极间产生电势差，实现钾离子的传输。
本申请实施例采取的技术方案还包括：所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料；
所述金属箔同时作为负极活性材料和负极集流体；
所述金属为钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中的至少一种；
或，所述合金为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的合金；
或，所述金属复合材料为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的复合材料；
金属箔为锡、锡合金或含锡的复合材料。
本申请实施例采取的技术方案还包括：所述电解液包括钾盐、添加剂和非水溶剂；
所述钾盐包括六氟磷酸钾、氯化钾、氟化钾、硫酸钾、碳酸钾、磷酸钾、硝酸钾、二氟草酸硼酸钾、焦磷酸钾、十二烷基苯磺酸钾、十二烷基硫酸钾、柠檬酸三钾、偏硼酸钾、硼酸钾、钼酸钾、钨酸钾、溴化钾、亚硝酸钾、碘酸钾、碘化钾、硅酸钾、木质素磺酸钾、草酸钾、铝酸钾、甲基磺酸钾、醋酸钾、重铬酸钾、六氟砷酸钾、四氟硼酸钾、高氯酸钾、三氟甲烷磺酰亚胺钾或三氟甲烷磺酸钾中的至少一种；
电解液中钾盐的浓度范围为0.1～10mol/L；
所述添加剂包括成膜添加剂、稳定剂、改善高低温性能添加剂、导电添加剂或阻燃添加剂中的至少一种；
添加剂包括氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、三氟代碳酸丙烯酯、1,3-丙磺酸内酯、硫酸乙烯酯、硫酸丙烯酯、硫酸亚乙酯、二甲基亚硫酸酯、二乙基亚硫酸酯、亚硫酸亚乙酯、氯代甲酸甲脂、二甲基亚砜、苯甲醚、乙酰胺、二氮杂苯、间二氮杂苯、12-冠醚-4、4-氟苯甲醚、氟代链状醚、二氟代甲基碳酸乙烯酯、三氟代甲基碳酸乙烯酯、氯代碳酸乙烯酯、溴代碳酸乙烯酯、三氟乙基膦酸、溴代丁内酯、氟代乙酸基乙烷、磷酸酯、亚磷酸酯、磷腈、乙醇胺、碳化二甲胺、环丁基砜、1,3-二氧环戊烷、乙腈、长链烯烃、氧化铝、氧化镁、碳酸钾、碳酸钙或碳酸锂中的至少一种，优选为氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯和三氟代碳酸丙烯酯中的至少一种；
电解液中添加剂的质量分数为0.1～20％；
所述非水溶剂包括碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、甲酸甲酯、乙酸甲酯、N,N-二甲基乙酰胺、氟代碳酸乙烯酯、丙酸甲酯、丙酸乙酯、乙酸乙酯、γ-丁内酯、四氢呋喃、2-甲基四氢呋喃、1,3-二氧环戊烷、4-甲基-1,3-二氧环戊烷、二甲氧甲烷、1,2-二甲氧丙烷、三乙二醇二甲醚、二甲基砜、二甲醚、亚硫酸乙烯酯、亚硫酸丙烯酯、亚硫酸二甲酯或亚硫酸二乙酯或冠醚中的至少一种，优选为碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂；
能够提供钾源的材料包括含钾的化合物或钾金属箔。
本申请实施例采取的技术方案还包括：所述电解液中钾盐的浓度范围为0.5～1.5mol/L。
本申请实施例采取的技术方案还包括：所述电解液中添加剂的质量分数为2～10％。
本申请实施例采取的技术方案还包括：对所述半电池进行充电和/或放电包括：将半电池连接到充放电测试仪上进行恒流放电，以设定的放电电量为标准，达到设定的放电电量后，停止测试，拆解得到预嵌钾负极；
放电电流为0.1～5C；
设定的放电电量为0.02～0.5mAh；
所述半电池还包括隔膜，所述隔膜包括多孔聚丙烯薄膜、多孔聚乙烯薄膜、多孔复合聚合物薄膜、玻璃纤维纸或多孔陶瓷隔膜中的一种或多种。
根据本申请的另一个方面，本申请提供一种以上所述的预嵌钾负极或由上述的预嵌钾负极的制备方法得到的预嵌钾负极在钾基双离子电池中的应用。
根据本申请的另一个方面，本申请提供一种钾基双离子电池，包括负极、正极、介于正负极之间的隔膜以及电解液；
所述负极为上述的预嵌钾负极或由上述的预嵌钾负极的制备方法得到的预嵌钾负极；
所述正极包括正极集流体和正极材料，正极材料包括正极材料活性物质，正极材料活性物质为能够可逆地插嵌、脱嵌电解液中阴离子的石墨类碳材料；
所述正极材料活性物质为膨胀石墨。
根据本申请的另一个方面，本申请提供一种钾基双离子电池的制备方法，将负极、电解液、隔膜以及正极进行组装，得到钾基双离子电池；
所述方法包括以下步骤：
(a)制备钾离子半电池，将钾离子半电池进行恒流充电和/或放电，以设定的放电电量为标准，停止测试后拆解得到预嵌钾负极；
(b)将步骤(a)得到的预嵌钾负极与电解液、隔膜以及正极进行组装，得到钾基双离子电池。
根据本申请的另一个方面，本申请提供一种用电设备，包括上述的钾基双离子电池或上述钾基双离子电池的制备方法得到的钾基双离子电池。
相对于现有技术，本申请实施例产生的有益效果在于：
1、本申请提供的预嵌钾负极，在金属箔材表面上设置有SEI膜层和/或钾-金属合金层，即在金属负极上预嵌钾以保护金属负极，还能够实现均匀的钾离子扩散，有效避免电池循环过程中由于钾离子与金属负极的不均匀合金化引起的部分体积膨胀严重和电极结构破坏。此外，钾离子的提前预嵌也有效减少了负极SEI膜形成过程中的钾离子不可逆消耗，从而保证了电池的循环稳定性以及高比容量。
2、本申请的制备方法通过预嵌钾的方式，在金属箔材表面形成稳定的SEI膜层和/或钾-金属合金层，保护了材料结构的同时引入了更多钾离子；能够提高负极的结构完整性或稳定性，有助于提高库伦效率，从而提高电池的稳定性及高倍率电流下充放电性能，进而克服现有的钾双离子电池中循环稳定性较差及高倍率电流条件下充放电性能显著下降等问题。同时，该制备方法简单易行，方便控制，过程安全，成本低廉，易于实现大规模工业化生产。
3、在金属箔材表面形成SEI膜层和/或钾-金属合金层，适量的钾-金属合金层既保证金属负极结构的完整性又改变金属箔材内部应力；SEI膜层相比于双离子电池自身反应不断生成的SEI膜更均匀也更稳定，可以保护金属负极的结构，降低了新SEI膜生成的速度；钾离子的提前预嵌缓解了双离子电池的电解液中钾盐的溶解局限，同时规避了SEI膜反复形成过程中钾盐钾过度消耗所带来容量衰减；稳定的SEI膜有利于钾离子从电解液到金属负极材料的快速传 输，能够有效提高双离子电池的首圈库伦效率。
4、本申请提供的钾基双离子电池或钾基双离子电池的制备方法，由于采用了上述了预嵌钾负极，因而具有成本低廉、结构稳定、库伦效率高、循环性能好、高倍率电流条件下充放电性能优异等优点。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发实施例7提供的钾基双离子电池的循环性能图；
图2是本申请实施例12提供的钾基双离子电池的倍率性能图；
图3是本申请实施例12提供的钾基双离子电池的充放电曲线图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，下面将结合实施方式和实施例对本申请的实施方案进行详细描述，但是本领域技术人员将会理解，下列实施方式和实施例仅用于说明本申请，而不应视为限制本申请的范围。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。未注明具体条件者，按照常规条件或制造商建议的条件进行。所用试剂或仪器未注明生产厂商者，均为可以通过市售购买获得的常规产品。
需要说明的是：
本申请中，如果没有特别的说明，本文所提到的所有实施方式以及优选实施方法可以相互组合形成新的技术方案。
本申请中，如果没有特别的说明，本文所提到的所有技术特征以及优选特征可以相互组合形成新的技术方案。
本申请中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。
本申请所公开的“范围”以下限和上限的形式，可以分别为一个或多个下限，和一个或多个上限。
本申请中，除非另有说明，各个反应或操作步骤可以顺序进行，也可以不按照顺序进行。优选地，本文中的方法是顺序进行的。
除非另有说明，本文中所用的专业与科学术语与本领域熟练人员所熟悉的意义相同。此外，任何与所记载内容相似或均等的方法或材料也可应用于本申请中。
现有技术中关于预嵌锂负极及其制备方法已经有了一些研究，例如公开号为CN104681311A的专利公开了一种锂离子电容器的预嵌锂方法。但是，在本申请的申请日之前尚未发现关于预嵌钾负极及其制备方法的相关报道。
预嵌钾与预嵌锂存在区别，两者的区别主要如下：(1)两者的目的不同，电容器制备中预嵌锂的步骤是为电容器的正常工作提供足量的锂离子，要求锂的嵌入量足够多；而本申请的目的之一是向金属箔材中嵌入适量的钾并在表面形成均匀的SEI膜，提高双离子电池的稳定性；(2)两者锂/钾源不同，预嵌锂只利用了电解液中的锂盐，需要反复充放电，多达100次，耗时过长，而本申请的目的之一是有效利用钾箔与金属箔材的电势差，小电流放电一次就能够 实现金属箔材的改性；(3)钾离子的离子半径相比锂离子要大，钾离子在电极材料中的嵌入也更困难，实现均匀嵌钾的负极表面改性较难；(4)由于两者的目的不同，本申请对金属箔材的嵌钾反应深度以及均匀性有其特殊的要求。因此本申请与锂离子电容器/电池中预嵌锂研究有较大的区别。
第一方面，在至少一个实施例中提供一种预嵌钾负极，所述负极包括：
金属箔和形成于金属箔表面上的SEI膜层；
或，金属箔和形成于金属箔表面上的钾-金属合金层；
或，金属箔，与所述金属箔相对设置的钾-金属合金层，以及设置于所述金属箔和钾-金属合金层之间的SEI膜层；
或，金属箔，与所述金属箔相对设置的SEI膜层，以及设置于所述金属箔和SEI膜层之间的钾-金属合金层。
为缓解现有的金属负极存在的不足，本申请提供一种预嵌钾负极以提高钾基双离子电池的稳定性及及高倍率电流下充放电性能，进而克服现有的钾基双离子电池中循环稳定性较差及高倍率电流条件下充放电性能显著下降的问题，从而为钾双离子电池的有效应用提供保证。
可以理解的是，本申请的预嵌钾负极包括金属箔和设置在所述金属箔表面上的SEI膜层和/或钾-金属合金层；
其中，所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料。
本申请通过预嵌钾的方式在金属负极表面生成均匀的固体电解质层(SEI膜)和/或钾-金属合金层用以保护钾双离子电池金属负极。表面均匀修饰SEI膜层和/或钾-金属合金层的金属箔负极用于钾双离子电池中能够实现均匀的钾离子扩散，有效避免电池循环过程中由于钾离子与金属负极的不均匀合金化 引起的部分体积膨胀严重和电极结构破坏。此外，钾离子的提前预嵌也有效减少了负极SEI膜形成过程中的钾离子不可逆消耗，从而保证了电池的循环稳定性以及高比容量。
需要说明的是：
“SEI膜”是指Solid Electrolyte Interface膜，即固体电解质膜，其形成于二次电池首次放电过程中，是电极材料与电解液在固液相界面上发生反应，从而形成的一层覆盖于电极材料表面的钝化层。SEI膜能在有机溶剂中稳定存在，并且能有效阻止溶剂分子的通过，避免溶剂分子与电极材料反应造成电极材料的破坏；而钾离子却可以经过该SEI膜自由地嵌入和脱出，不会对电池的充放电以及循环性能产生不良影响。但是，SEI在形成过程中消耗了钾离子，产生不可逆的充放电容量,降低了电极材料的充放电效率。在循环过程中，固液相界面的变化造成SEI不断的增长，消耗电解液，会造成容量的加速衰减。过厚的SEI膜增加了界面的钾离子传输阻抗，降低了整个体系的动力学。
“钾-金属合金层”是指，含钾的材料与金属箔材发生合金化反应形成的金属材料与钾的合金，其既能够保证金属负极结构的完整性，又可以改变金属箔材的内部应力。
“SEI膜层和/或钾-金属合金层”是指，在金属箔材表面上形成SEI膜层，或者在金属箔材表面上形成钾-金属合金层，或者在金属箔材表面上形成SEI膜层和钾-金属合金层。
“能够与钾离子发生合金化/去合金化作用的金属、合金或金属复合材料”是指能够与钾离子发生合金化/去合金化作用的金属、能够与钾离子发生合金化/去合金化作用的合金材料或能够与钾离子发生合金化/去合金化作用的金属复合导电材料。
“合金”是指由两种或两种以上的金属与金属或非金属经一定方法所合成的具有金属特性的物质。
“金属复合材料”是指金属与其他非金属材料结合所形成的金属基复合导电材料。典型但非限制性的金属复合材料包括石墨烯-金属复合材料、碳纤维-金属复合材料或陶瓷-金属复合材料等。
可以理解的是，本申请对于金属箔材的具体类型没有特殊限制，只要不对本申请的目的产生限制即可。
在一种优选的实施方式中，所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料；
优选地，金属箔同时作为负极活性材料和负极集流体。
采用能够与钾离子合金化/去合金化作用的金属箔片同时作为负极活性材料和负极集流体，起到导电和发生反应的双重作用，使常规钾离子电池负极的负极活性材料和负极集流体两种要素省略为一种，相比于现有技术中的负极通常包括起导电作用的集流体和用于发生反应的活性材料，节省了一个部件的体积和重量，简化了器件制造工艺，且有利于增加活性材料占比，能够获得更高的能量密度，进一步增加了电池的能量密度和比容量；并且该负极材料含量丰富，价格更低廉，有效降低了电池的生产成本。
负极金属箔材为可以与钾形成合金的相关金属、合金或金属复合材料。
优选地，所述金属为钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中的至少一种，优选为钠、锡、锂、锌、铅或锗中的至少一种；
或，所述合金为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的合金，优选为至少包含钠、锡、锂、锌、铅或锗中任意一种的合金；上述合金典型但非限制性的为铝锡合金、钠锌合金、铜铁合金、锌 镍合金、锑铋合金、铝锡镁合金或镍钛锰合金等。
或，所述金属复合材料为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的复合材料，优选为至少包含钠、锡、锂、锌、铅或锗中任意一种的复合材料；上述复合材料典型但非限制性的为锡/石墨烯复合箔片、钠/石墨烯复合箔片或锌/石墨烯复合箔片等。
优选地，金属箔为锡、锡合金或含锡的复合材料，
更优选地，金属箔为锡箔。
需要说明的是，上述金属材料的形态优选为箔材，制备得到的预嵌钾负极的形态优选为片状。
第二方面，在至少一个实施例中提供一种预嵌钾负极的制备方法，提供一半电池，对所述半电池进行充电和/或放电；
其中，所述半电池的负极为金属箔；
所述半电池的电解液为含有添加剂的钾盐溶液；
所述半电池的对电极为能够提供钾源的材料，对电极与负极间产生高电势差，实现钾离子的传输。
根据本申请，为缓解现有的金属负极存在的问题，提出了一种通过预嵌钾以提高钾双离子电池稳定性及高倍率电流下充放电性能的方法，克服现有钾双离子电池中循环稳定性较差及高倍率电流条件下充放电性能显著下降的问题，从而为钾双离子电池的有效应用提供保证。该方法制得的预嵌钾负极包括金属箔材和设置在所述金属箔材表面上的SEI膜层和/或钾-金属合金层，并具有以下特点：(1)适量的钾-金属合金层既保证金属负极结构的完整性又改变金属箔材内部应力；(2)小电流预放电所生成的SEI膜相比于双离子电池自身反应不断生成的SEI膜更均匀也更稳定，可以保护金属负极的结构，降低了新SEI 膜生成的速度；(3)钾离子的提前预嵌也缓解了双离子电池的电解液中钾盐的溶解局限，同时规避了SEI膜反复形成过程中钾盐钾过度消耗所带来容量衰减；(4)稳定的SEI膜有利于钾离子从电解液到金属负极材料的快速传输，能够有效提高双离子电池的首圈库伦效率。
此外，上述方法操作简单，容易实现，可控性好，成本低廉，易于推广应用。
需要说明的是，“钾源”为能够提供钾源的材料，是指含有钾的材料，并且材料中的钾在半电池充电或放电过程中与负极金属箔材产生高电势差实现钾离子的有效传输，进而与在负极金属箔材的表面形成SEI膜层和/或钾-金属合金层。
可以理解的是，该制备方法中的金属箔的优选实施方式，可参见上述预嵌钾负极中的金属箔的优选实施方式，在此不再赘述。
在一种优选的实施方式中，所述电解液包括钾盐、添加剂和非水溶剂；电解液中的添加剂可用于提高SEI膜的稳定性和均一性。
需要说明的是，本申请对于半电池电解液中钾盐的具体类型没有特殊限制，可采用本领域常用的钾盐，只要不对本申请的目的产生限制即可。
优选地，所述钾盐包括但不限于六氟磷酸钾、氯化钾、氟化钾、硫酸钾、碳酸钾、磷酸钾、硝酸钾、二氟草酸硼酸钾、焦磷酸钾、十二烷基苯磺酸钾、十二烷基硫酸钾、柠檬酸三钾、偏硼酸钾、硼酸钾、钼酸钾、钨酸钾、溴化钾、亚硝酸钾、碘酸钾、碘化钾、硅酸钾、木质素磺酸钾、草酸钾、铝酸钾、甲基磺酸钾、醋酸钾、重铬酸钾、六氟砷酸钾、四氟硼酸钾、高氯酸钾、三氟甲烷磺酰亚胺钾或三氟甲烷磺酸钾中的一种或至少两种，
更优选地，钾盐为六氟磷酸钾。
优选地，电解液中钾盐的浓度范围为0.1～10mol/L，优选为0.5～1.5mol/L；上述钾盐的浓度典型但非限制性的为0.1mol/L、0.5mol/L、1mol/L、1.5mol/L、2mol/L、3mol/L、4mol/L、5mol/L、6mol/L、7mol/L、8mol/L、9mol/L或10mol/L。
需要说明的是，本申请对于半电池电解液中添加剂的具体类型没有特殊限制，只要可提高SEI膜的稳定性和均一性，不对本申请的目的产生限制即可。
优选地，所述添加剂包括成膜添加剂、稳定剂、改善高低温性能添加剂、导电添加剂或阻燃添加剂中的至少一种；
优选地，添加剂包括氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、三氟代碳酸丙烯酯、1,3-丙磺酸内酯、硫酸乙烯酯、硫酸丙烯酯、硫酸亚乙酯、二甲基亚硫酸酯、二乙基亚硫酸酯、亚硫酸亚乙酯、氯代甲酸甲脂、二甲基亚砜、苯甲醚、乙酰胺、二氮杂苯、间二氮杂苯、12-冠醚-4、4-氟苯甲醚、氟代链状醚、二氟代甲基碳酸乙烯酯、三氟代甲基碳酸乙烯酯、氯代碳酸乙烯酯、溴代碳酸乙烯酯、三氟乙基膦酸、溴代丁内酯、氟代乙酸基乙烷、磷酸酯、亚磷酸酯、磷腈、乙醇胺、碳化二甲胺、环丁基砜、1,3-二氧环戊烷、乙腈、长链烯烃、氧化铝、氧化镁、碳酸钾、碳酸钙或碳酸锂中的至少一种，优选为氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯和三氟代碳酸丙烯酯中的至少一种；
更优选地，添加剂为氟代碳酸乙烯酯(FEC)、碳酸亚乙烯酯(VC)、碳酸乙烯亚乙酯(VEC)或三氟代碳酸丙烯酯(TFPC)中的一种或至少两种。
优选地，电解液中添加剂的质量分数为0.1～20％，优选为2～10％；上述添加剂的质量分数典型但非限制性的为0.1％、0.5％、1％、2％、4％、6％、8％、10％、12％、14％、16％、18％或20％。通过调节添加剂的质量分数，可以调控高SEI膜的稳定性和均一性，当添加剂的质量分数为0.1～20％时，SEI的厚度 合理，稳定性和均一性好，同时不会影响负极的电化学性能。
需要说明的是，本申请对于半电池电解液中非水溶剂的具体类型没有特殊限制，可采用本领域常用的非水溶剂，只要不对本申请的目的产生限制即可。
优选地，所述非水溶剂包括碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸甲乙酯(EMC)、甲酸甲酯(MF)、乙酸甲酯(MA)、N,N-二甲基乙酰胺(DMA)、氟代碳酸乙烯酯(FEC)、丙酸甲酯(MP)、丙酸乙酯(EP)、乙酸乙酯(EA)、γ-丁内酯(GBL)、四氢呋喃(THF)、2-甲基四氢呋喃(2MeTHF)、1,3-二氧环戊烷(DOL)、4-甲基-1,3-二氧环戊烷(4MeDOL)、二甲氧甲烷(DMM)、1,2-二甲氧丙烷(DMP)、三乙二醇二甲醚(DG)、二甲基砜(MSM)、二甲醚(DME)、亚硫酸乙烯酯(ES)、亚硫酸丙烯脂(PS)、亚硫酸二甲脂(DMS)、亚硫酸二乙脂(DES)或冠醚(12-冠-4)中的至少一种。
上述溶剂典型但非限制性的为碳酸丙烯酯，碳酸乙烯酯，碳酸二乙酯，碳酸二甲酯，碳酸甲乙酯，甲酸甲酯，乙酸甲酯，N,N-二甲基乙酰胺，氟代碳酸乙烯酯，丙酸甲酯，丙酸乙酯，乙酸乙酯，γ-丁内酯，四氢呋喃，2-甲基四氢呋喃，1,3-二氧环戊烷，4-甲基-1,3-二氧环戊烷，二甲氧甲烷，1,2-二甲氧丙烷，三乙二醇二甲醚，二甲基砜，二甲醚，亚硫酸乙烯酯，亚硫酸丙烯脂，亚硫酸二甲脂，亚硫酸二乙脂，冠醚(12-冠-4)，碳酸丙烯酯和碳酸乙烯酯的组合，碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的组合，碳酸二乙酯和碳酸二甲酯的组合，碳酸甲乙酯和甲酸甲酯的组合，乙酸甲酯和N,N-二甲基乙酰胺的组合，氟代碳酸乙烯酯和丙酸甲酯的组合，丙酸乙酯和乙酸乙酯的组合，γ-丁内酯和四氢呋喃的组合，2-甲基四氢呋喃和1,3-二氧环戊烷的组合，1,2-二甲氧丙烷和三乙二醇二甲醚的组合，二甲基砜和二甲醚的组合，亚硫酸乙烯酯和亚硫酸 丙烯脂的组合，碳酸丙烯酯、碳酸乙烯酯和碳酸二乙酯的组合，碳酸二甲酯、碳酸甲乙酯和甲酸甲酯的组合，乙酸甲酯、N,N-二甲基乙酰胺和氟代碳酸乙烯酯的组合，丙酸甲酯、丙酸乙酯和乙酸乙酯的组合，γ-丁内酯、四氢呋喃和2-甲基四氢呋喃的组合，1,3-二氧环戊烷、4-甲基-1,3-二氧环戊烷和二甲氧甲烷的组合，二甲醚、亚硫酸乙烯酯和亚硫酸丙烯脂的组合，或，亚硫酸二甲脂、亚硫酸二乙脂和冠醚(12-冠-4)的组合等。
更优选地，非水溶剂为碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂。
在一种优选的实施方式中，所述钾源包括含钾的化合物或钾金属箔；
优选地，所述钾源为钾金属箔。
根据本申请，半电池中包含钾源，半电池钾源能与负极产生高电势差实现钾离子的有效传输。
上述“含钾的化合物”是指，钾与其他一种或两种以上元素组成的物质。例如，含钾的化合物可以为硫化钾氟化钾、草酸钾、钴酸钾等。
本申请中，钾源优选采用的是平整的钾金属箔。
在一种优选的实施方式中，对所述半电池进行充电和/或放电包括：将半电池连接到充放电测试仪上进行恒流放电，以设定的放电电量为标准，达到设定的放电电量后，停止测试，拆解得到预嵌钾负极；
优选地，放电电流为0.1～5C；
优选地，放电电量为0.02～0.5mAh；
优选地，所述半电池还包括隔膜，所述隔膜包括多孔聚丙烯薄膜、多孔聚乙烯薄膜、多孔复合聚合物薄膜、玻璃纤维纸或多孔陶瓷隔膜中的一种或多种。
可以理解的是，本申请对于半电池隔膜没有特殊限制，可采用本领域常用的隔膜，只要不对本申请的目的产生限制即可。
以上可以看出，本申请所采用的预嵌钾改性金属负极是将钾金属置于负极，金属箔材为对电极制备钾离子半电池，将半电池放到充放电测试仪上，恒流放电，控制放电量，得到表面均匀覆盖SEI膜层及均匀预嵌钾的金属箔材，将改性后的金属箔材-预嵌钾负极作为钾双离子电池的负极。主要具有以下特征：(1)适量的钾-金属合金层既保证金属负极结构的完整性又改变金属箔材内部应力；(2)小电流预放电所生成的SEI膜相比于双离子电池自身反应不断生成的SEI膜更均匀也更稳定，可以保护金属负极的结构，降低了新SEI膜生成的速度；(3)钾离子的提前预嵌也缓解了双离子电池的电解液中钾盐的溶解局限，同时规避了SEI膜反复形成过程中钾盐钾过度消耗所带来容量衰减；(4)稳定的SEI膜有利于钾离子从电解液到金属负极材料的快速传输，能够有效提高双离子电池的首圈库伦效率。
进一步的，根据本申请，该制备方法中，负极金属箔材要求能够与钾形成钾-金属合金，实现钾的预嵌；预嵌钾半电池钾源与负极间产生高电势差，实现钾离子的有效传输；电解液中的添加剂用于提高SEI膜的稳定性和均一性。此外，对于预嵌钾半电池放电电流和放电电量的调控同样具有重要作用。预嵌钾半电池放电电流用于控制钾-金属合金晶粒尺寸和优化金属箔的内部应力；预嵌钾半电池放电电量用于控制钾-金属合金层的厚度及稳定程度可以为导电碳材料、导电金属材料也可以是导电高分子。
在本申请技术方案的基础上，预嵌钾半电池放电电流用于控制钾-金属合金晶粒尺寸和优化金属箔的内部应力，控制预嵌钾过程的放电电流为0.1～5C；典型但非限制性的放电电流例如可以为0.1C、0.2C、0.5C、0.6C、0.9C、1C、1.5C、2C、2.5C、3C、3.5C、4C、4.5C或5C。
在本申请技术方案的基础上，预嵌钾半电池放电电量用于控制钾-金属合 金层的厚度及稳定程度可以为导电碳材料、导电金属材料也可以是导电高分子，控制预嵌钾过程的放电电量为0.02～0.5mAh；典型但非限制性的放电电量例如可以为0.02mAh、0.05mAh、0.08mAh、0.1mAh、0.15mAh、0.2mAh、0.25mAh、0.3mAh、0.4mAh或0.5mAh。
进一步地，所述预嵌钾负极的制备方法包括以下步骤：
(a)将负极金属箔清洗干净，干燥后进行裁切并冲压平整，得所需尺寸的金属箔，备用；
(b)将所需尺寸的多孔聚合物薄膜或无机多孔薄膜或有机/无机复合隔膜作为隔膜，将其冲切成所需尺寸，备用；
(c)将钾金属碾压平整后裁切成所需尺寸(其尺寸略大于金属箔尺寸)，备用；
(d)配制含有添加剂的电解液，备用；
(e)将上述金属箔、隔膜、钾箔和电解液组装成钾离子半电池；
(f)将钾离子半电池连接到充放电测试仪上，以恒定的适量电流进行一次放电，以设定的放电量为标准，达到设定的放电量后停止测试取下电池，拆解电池得到的预嵌钾的金属箔片即为预嵌钾负极。
第三方面，在至少一个实施例中提供一种所述的预嵌钾负极或所述的预嵌钾负极的制备方法得到的预嵌钾负极在钾基双离子电池中的应用。
将本申请的预嵌钾负极应用在钾基双离子中，可得到新的钾离子电池体系，缓解现有的电池循环稳定性较差，首圈库伦效率低，高倍率电流条件下充放电性能显著下降的问题。即本申请通过预嵌钾的方式得到均匀的钾-金属合金层和稳定的SEI膜层，保护了材料结构的同时引入了更多钾离子。
第四方面，在至少一个实施例中提供一种钾基双离子电池，包括负极、正 极、介于正负极之间的隔膜以及电解液；
所述负极为以上所述的预嵌钾负极或以上所述的预嵌钾负极的制备方法得到的预嵌钾负极；
优选地，所述正极包括正极集流体和正极材料，正极材料包括正极材料活性物质，正极材料活性物质为能够可逆地插嵌、脱嵌电解液中阴离子的石墨类碳材料；
优选地，所述正极材料活性物质为膨胀石墨。
根据本申请，该钾基双离子电池为简便、可控性好的预嵌钾改性双离子电池，提高了钾双离子电池稳定性及高倍率电流下充放电性能的方法，克服了现有钾双离子电池中循环稳定性较差及高倍率电流条件下充放电性能显著下降的问题。
应当理解的是，上述钾基双离子电池的核心在于包括采用上述预嵌钾负极，除此之外，该钾基双离子电池还包括现有双离子电池的其他组件或部件，例如，与预嵌钾负极相匹配的正极、电解液、隔膜和壳体等，本申请对此并不作特别限制；另外，该钾基双离子电池的制备方法也可采用现有的制备方法进行制备即可，本申请对此并不作特别限制。
在一种优选的实施方式中，所述双离子电池正极包括正极集流体和正极材料，正极材料包括正极材料活性物质，正极材料活性物质为能够可逆地插嵌、脱嵌电解液中阴离子的石墨类碳材料；
优选地，所述正极活性材料为膨胀石墨；
优选地，所述正极集流体为铝、铜、锡、锌、铅、铁、镍、金、镁、锌或锗中任意一种的金属；或，所述正极集流体为至少包含铝、铜、锡、锌、铅、铁、镍、金、镁、锌或锗中任意一种的合金；或，所述正极集流体为至少包含 铝、铜、锡、锌、铅、铁、镍、金、镁、锌或锗中任意一种的金属复合物；优选地，优选为涂炭铝箔；
优选地，导电剂包括导电炭黑、导电碳球、导电石墨、碳纳米管、碳纤维或石墨烯中的一种或至少两种；
优选地，粘结剂包括聚偏氟乙烯、聚四氟乙烯、聚乙烯醇、羧甲基纤维素、SBR橡胶、聚烯烃类粘结剂中的一种或至少两种；
优选地，在本申请技术方案的基础上，正极材料包括70～95wt％的正极材料活性物质、2～20wt％的导电剂和3～10wt％的粘结剂；
优选地，隔膜包括多孔聚丙烯薄膜、多孔聚乙烯薄膜、多孔复合聚合物薄膜、玻璃纤维纸、多孔陶瓷隔膜中的一种或多种。
优选地，将正极和负极连接的方式为组装为半电池后将正极和负极通过充放电设备进行连接。
第五方面，在至少一个实施例中提供一种所述的钾基双离子电池的制备方法，将负极、电解液、隔膜以及正极进行组装，得到钾基双离子电池。
优选地，所述方法包括以下步骤：
(a)制备钾离子半电池，将钾离子半电池进行恒流充电和/或放电，以设定的放电电量为标准，停止测试后拆解得到预嵌钾负极；
(b)将步骤(a)得到的预嵌钾负极与电解液、隔膜以及正极进行组装，得到钾基双离子电池。
可以理解的是，上述钾基双离子电池的制备方法，即通过预嵌钾以提高钾基双离子电池性能的方法，主要包括两个阶段：
阶段一：制备钾-金属箔半电池电池，将钾离子半电池连接到充放电测试仪上进行恒定的电流放电，以设定的放电量为标准，停止测试后拆解电池得到 预处理后的金属箔，即预嵌钾负极。
阶段二：拆解后的金属箔作为双离子电池的负极重新组装为改性后的钾基双离子电池。
需要说明的是，钾半电池电解液包括钾盐、电解液添加剂和非水溶剂。钾基双离子电池电解液包括钾盐和非水溶剂。其中钾基双离子电池电解液中的钾盐和非水溶剂，均可参照上述的半电池电解液中的钾盐和非水溶剂的介绍，二者可采用相同或类似的钾盐和电解液。
进一步的，双离子电池的电解质包括液态电解液、凝胶电解质或固体电解质。
将正极和负极连接的方式为组装为半电池后将正极和负极通过充放电设备进行连接。
在本申请的一种优选实施方式中，该钾基双离子电池的制备方法，包括以下步骤：
阶段一：制备钾-金属箔半电池，将钾离子半电池连接到充放电测试仪上进行恒定的电流放电，以设定的放电量为标准，停止测试后拆解电池得到预处理后的金属箔。
步骤1：制备金属箔材：将负极金属箔清洗干净，干燥后进行裁切并冲压平整，得所需尺寸的金属箔；
步骤2：制备隔膜：将所需尺寸的多孔聚合物薄膜或无机多孔薄膜或有机/无机复合隔膜作为隔膜，将其冲切成所需尺寸；
步骤3：制备钾箔：将钾金属碾压平整后裁切成所需尺寸，其尺寸略大于金属箔尺寸；
步骤4：配制半电池电解液：将钾盐电解质与相应添加剂溶于非水溶剂中， 充分混合得到电解液；
步骤5：将步骤3得到的钾箔、步骤4得到的电解液、步骤2得到的隔膜以及步骤1得到的金属箔材进行组装，得到钾离子半电池；
步骤6：将步骤5中得到的钾离子半电池连接到充放电测试仪上，以恒定的适量电流进行一次放电，以设定的放电量为标准，达到设定的放电量后停止测试取下电池；
步骤7：将步骤6中适度放电的半电池进行拆解，取出钾箔留以重复利用，完整取出金属箔材即为改性后的双离子电池负极材料-预嵌钾负极。
阶段二：拆解后的金属箔作为双离子电池的负极重新组装为改性后的钾基双离子电池。
步骤8：制备双离子电池正极：首先按照一定的比例称取适当的正极活性材料、粘结剂与导电剂，研磨均匀后，加入适量溶剂，充分混合成均匀浆料制成正极活性材料层；将金属、金属合金或金属复合物导电材料作为正极集流体，将上述正极活性材料层均匀涂覆于正极集流体表面，放置于一定温度的真空干燥箱内进行干燥内，待所述正极活性材料层完全干燥后冲裁成所需尺寸的正极。
步骤9：配制双离子电池电池电解液：将钾盐电解质溶于非水溶剂中，充分混合得到电解液；
步骤10：将步骤7得到的改性金属箔、步骤9得到的电解液、步骤2得到的隔膜以及步骤8得到正极进行组装，得到钾基双离子电池。
第六方面，在至少一个实施例中提供一种用电设备，包括上述的钾基双离子电池或上述钾基双离子电池的制备方法得到的钾基双离子电池。
该用电设备包括上述钾基双离子电池，因而至少具有与上述钾基双离子电 池相同的优势，具有成本低廉、能量密度高和循环稳定性好的优点，该用电设备在相同的充放电电流以及相同环境下使用时，使用寿命更长。
上述用电设备包括但不限于电子装置、电动工具或电动车辆等。电子装置是使用上述钾基双离子电池作为操作电源执行各种功能(例如，演奏音乐)的电子装置。电动工具是使用上述钾基双离子电池作为驱动电源移动部件(例如，钻头)的电动工具。电动车辆是依靠上述钾基双离子电池作为驱动电源运行的电动车辆(包括电动自行车、电动汽车)，并且可以是除了上述储能器件之外还装备有其他驱动源的汽车(包括混合动力车)。
下面结合具体实施例、对比例和附图，对本申请作进一步说明。
实施例1
一种预嵌钾负极的制备方法，包括以下步骤：
(1)：制备金属箔材：将锡箔清洗干净，干燥后裁切成直径12mm的圆片并冲压平整备用。
(2)：制备隔膜：将玻璃纤维薄膜在真空80℃条件下干燥24h，之后裁切成直径16mm的圆片作为隔膜。
(3)：制备钾箔：将钾金属碾压平整后裁切成直径14mm的圆片备用。
(4)：配制半电池电解液：称取1.8408g六氟磷酸钾加入到10mL碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(体积比为4:3:2)，搅拌至六氟磷酸钾完全溶解(电解液浓度为1M)，加入2％的氟代碳酸乙烯酯(FEC)作为添加剂，充分搅拌均匀后作为半电池电解液备用。
(5)：在惰性气体保护的手套箱中，将上述制备好的钾箔、隔膜以及锡箔依次紧密堆叠，滴加所制得的电解液使隔膜完全浸润，然后将上述封装入扣式壳体，完成钾离子半电池的组装。
(6)：将步骤(5)中得到的钾离子半电池连接到充放电测试仪上，以0.2C电流进行一次放电，设定总放电量为0.02mAh，之后停止测试取下电池。
(7)：将步骤(6)中适度放电的半电池进行拆解，取出钾箔留以重复利用，完整取出金属箔材即为改性后的双离子电池负极材料-预嵌钾负极。
实施例2-10
一种预嵌钾负极的制备方法，与实施例1的区别仅在于，步骤(6)中的预嵌钾放电电量；其他步骤及其参数均与实施例1相同。
包括实施例1-10中制备得到的预嵌钾负极的钾基双离子电池，制备方法包括以下步骤：
(a)制备双离子电池正极：称量0.1g导电碳黑、0.1g聚偏氟乙烯、0.8g膨胀石墨在研钵中混合均匀，逐滴滴加2ml氮甲基吡咯烷酮溶液，再次充分研磨得到均匀浆料；然后在铝箔表面上均匀刮涂浆料，在真空80℃条件下干燥12h。将干燥后的电极片裁切成直径10mm的圆片，作为双离子电池正极。
(b)配制双离子电池电池电解液：称取1.8408g六氟磷酸钾加入到10mL碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(体积比为4:3:2)，搅拌至六氟磷酸钾完全溶解(电解液浓度为1M)，充分搅拌均匀后作为双离子电池电解液备用。
(c)在惰性气体保护的手套箱中，将上述步骤(7)得到的预嵌钾负极、步骤(2)得到的隔膜以及步骤(a)得到正极依次紧密堆叠，滴加步骤(b)得到的电解液使隔膜完全浸润，然后将上述封装入扣式壳体，完成钾基双离子电池的组装。
对实施例1和实施例2-10提供的钾基双离子电池进行电化学性能测试，包括循环次数、容量保持率和库伦效率，测试结果如表1所示。测试方法如下：
循环充放电：循环充放电在CT2001C-001蓝电电池循环测试系统上进行，以5C倍率充放来测试电极的标准容量，材料的比容量＝电流*时间/样品质量,材料的能量密度＝材料的比容量*电池的平台电压，充放电的条件视实验的需要而定,循环步骤包括：静置60s-恒流放电-静置60s-恒流充电。
倍率充放电：同样在蓝电电池循环测试系统上进行,以不同的倍率(电流密度)进行充放来测试材料的倍率性能,充放电的条件视实验的需要而定,循环步骤与循环充放电相同。
表1实施例1-10的预嵌钾负极的主要制备条件及钾基双离子电池性能参数表
Figure PCTCN2019125433-appb-000001
此外，图1显示了本申请实施例7提供的钾基双离子电池的循环性能图，即在预嵌钾过程中添加2％FEC电解液添加剂，预嵌钾放电电流为0.2C，放电电量为0.2mAh的双离子电池的循环性能图。从图1恒流充放电比容量及库伦效率图中可以看出，本申请的钾基双离子电池的库伦效率高，比容量高。
实施例11-20
实施例11-20与实施例1中预嵌钾改性的钾基双离子电池制备工艺和测试过程步骤相同，区别在于预嵌钾半电池的放电电流不同。实施例11-20的测试结果如表2所示。
表2实施例11-20的预嵌钾负极的主要制备条件及钾基双离子电池性能参数表
Figure PCTCN2019125433-appb-000002
此外，图2显示了本申请实施例12提供的钾基双离子电池的倍率性能图，即在预嵌钾过程中添加2％FEC电解液添加剂，预嵌钾放电电流为0.5C，放电电量为0.2mAh的双离子电池的倍率性能图。图3显示了本申请实施例12提供的钾基双离子电池的充放电曲线图，即在预嵌钾过程中添加2％FEC电解液添加剂，预嵌钾放电电流为0.5C，放电电量为0.2mAh的双离子电池的充放电曲线图。从图2不同倍率电流密度下充放电比容量图和图3不同倍率电流密度下充放电曲线图中可以看出，本申请的钾基双离子电池具有优异的电化学性能。
实施例21-30
实施例21-30与实施例1中预嵌钾改性的钾基双离子电池制备工艺和测试过程步骤相同，区别在于预嵌钾半电池的添加剂不同。实施例21-30的测试结果如表3所示。
表3实施例21-30的预嵌钾负极的主要制备条件及钾基双离子电池性能参数表
Figure PCTCN2019125433-appb-000003
实施例31-34
实施例31-34与实施例1中预嵌钾改性的钾基双离子电池制备工艺和测试过程步骤相同，区别在于预嵌钾半电池的负极活性材料不同。实施例31-36的测试结果如表4所示。
表4实施例31-36的预嵌钾负极的主要制备条件及钾基双离子电池性能参数表
Figure PCTCN2019125433-appb-000004
对比例1
一种预嵌钾负极的制备方法，与实施例1不同的是，本对比例的电解液中不含氟代碳酸乙烯酯添加剂。
将对比例1制备得到的预嵌钾负极制备成钾基双离子电池，制备方法同实施例1。用与实施例1相同的方法对对比例1的钾基双离子电池进行性能测试，经测试，对比例1的电池循环300次容量保持率为80％、能量密度为81mAh/g，以上性能均低于实施例1。可以看出，氟代碳酸乙烯酯添加剂的加入有利于形成稳定的SEI膜，提高了双离子电池的循环稳定性。
对比例2
一种钾基双离子电池的制备方法，与实施例1的区别在于负极，对比例2所采用的负极为现有的负极，即为锡箔；其余均为实施例1相同。
将对比例2制备得到的钾基双离子电池，进行性能测试，经测试，对比例2的电池循环300次容量保持率为74％、能量密度为69mAh/g，以上性能均低于实施例1。可以看出，预嵌钾后的锡箔相比于未处理的锡箔稳定性更高，其内部结构更具优势，能够有效地缓冲脱嵌钾引起的体积变化。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围。

Claims (12)

  1. 一种预嵌钾负极，其特征在于，所述负极包括：
    金属箔和形成于金属箔表面上的SEI膜层；
    或，金属箔和形成于金属箔表面上的钾-金属合金层；
    或，金属箔，与所述金属箔相对设置的钾-金属合金层，以及设置于所述金属箔和钾-金属合金层之间的SEI膜层；
    或，金属箔，与所述金属箔相对设置的SEI膜层，以及设置于所述金属箔和SEI膜层之间的钾-金属合金层。
  2. 根据权利要求1所述预嵌钾负极，其特征在于，所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料；
    所述金属箔同时作为负极活性材料和负极集流体；
    所述金属为钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中的至少一种；
    或，所述合金为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的合金；
    或，所述金属复合材料为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的复合材料；
    金属箔为锡、锡合金或含锡的复合材料。
  3. 一种预嵌钾负极的制备方法，其特征在于，提供一半电池，对所述半电池进行充电和/或放电；
    其中，所述半电池的负极为金属箔；
    所述半电池的电解液为含有添加剂的钾盐溶液；
    所述半电池的对电极为能够提供钾源的材料，对电极与负极间产生电势差，实现钾离子的传输。
  4. 根据权利要求3所述预嵌钾负极的制备方法，其特征在于，所述金属箔为能够与钾离子合金化/去合金化作用的金属、合金或金属复合材料；
    所述金属箔同时作为负极活性材料和负极集流体；
    所述金属为钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中的至少一种；
    或，所述合金为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的合金；
    或，所述金属复合材料为至少包含钠、锡、锂、锌、铅、锗、铜、铁、镍、钛、锰、锑或铋中任意一种的复合材料；
    金属箔为锡、锡合金或含锡的复合材料。
  5. 根据权利要求3所述预嵌钾负极的制备方法，其特征在于，所述电解液包括钾盐、添加剂和非水溶剂；
    所述钾盐包括六氟磷酸钾、氯化钾、氟化钾、硫酸钾、碳酸钾、磷酸钾、硝酸钾、二氟草酸硼酸钾、焦磷酸钾、十二烷基苯磺酸钾、十二烷基硫酸钾、柠檬酸三钾、偏硼酸钾、硼酸钾、钼酸钾、钨酸钾、溴化钾、亚硝酸钾、碘酸钾、碘化钾、硅酸钾、木质素磺酸钾、草酸钾、铝酸钾、甲基磺酸钾、醋酸钾、重铬酸钾、六氟砷酸钾、四氟硼酸钾、高氯酸钾、三氟甲烷磺酰亚胺钾或三氟甲烷磺酸钾中的至少一种；
    电解液中钾盐的浓度范围为0.1～10mol/L；
    所述添加剂包括成膜添加剂、稳定剂、改善高低温性能添加剂、导电添加剂或阻燃添加剂中的至少一种；
    添加剂包括氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、三氟代碳酸丙烯酯、1,3-丙磺酸内酯、硫酸乙烯酯、硫酸丙烯酯、硫酸亚乙酯、二甲基亚硫酸酯、二乙基亚硫酸酯、亚硫酸亚乙酯、氯代甲酸甲脂、二甲基亚砜、苯甲醚、乙酰胺、二氮杂苯、间二氮杂苯、12-冠醚-4、4-氟苯甲醚、氟代链状醚、二氟代甲基碳酸乙烯酯、三氟代甲基碳酸乙烯酯、氯代碳酸乙烯酯、溴代碳酸乙烯酯、三氟乙基膦酸、溴代丁内酯、氟代乙酸基乙烷、磷酸酯、亚磷酸酯、磷腈、乙醇胺、碳化二甲胺、环丁基砜、1,3-二氧环戊烷、乙腈、长链烯烃、氧化铝、氧化镁、碳酸钾、碳酸钙或碳酸锂中的至少一种，优选为氟代碳酸乙烯酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯和三氟代碳酸丙烯酯中的至少一种；
    电解液中添加剂的质量分数为0.1～20％；
    所述非水溶剂包括碳酸丙烯酯、碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯、碳酸甲乙酯、甲酸甲酯、乙酸甲酯、N,N-二甲基乙酰胺、氟代碳酸乙烯酯、丙酸甲酯、丙酸乙酯、乙酸乙酯、γ-丁内酯、四氢呋喃、2-甲基四氢呋喃、1,3-二氧环戊烷、4-甲基-1,3-二氧环戊烷、二甲氧甲烷、1,2-二甲氧丙烷、三乙二醇二甲醚、二甲基砜、二甲醚、亚硫酸乙烯酯、亚硫酸丙烯酯、亚硫酸二甲酯或亚硫酸二乙酯或冠醚中的至少一种，优选为碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂；
    能够提供钾源的材料包括含钾的化合物或钾金属箔。
  6. 根据权利要求5所述预嵌钾负极的制备方法，其特征在于，所述电解液中钾盐的浓度范围为0.5～1.5mol/L。
  7. 根据权利要求5所述预嵌钾负极的制备方法，其特征在于，所述电解液中添加剂的质量分数为2～10％。
  8. 根据权利要求3～7任一项所述预嵌钾负极的制备方法，其特征在于，对所述半电池进行充电和/或放电包括：将半电池连接到充放电测试仪上进行恒流放电，以设定的放电电量为标准，达到设定的放电电量后，停止测试，拆解得到预嵌钾负极；
    放电电流为0.1～5C；
    设定的放电电量为0.02～0.5mAh；
    所述半电池还包括隔膜，所述隔膜包括多孔聚丙烯薄膜、多孔聚乙烯薄膜、多孔复合聚合物薄膜、玻璃纤维纸或多孔陶瓷隔膜中的一种或多种。
  9. 权利要求1～2任一项所述的预嵌钾负极或权利要求3～8任一项所述的预嵌钾负极的制备方法得到的预嵌钾负极在钾基双离子电池中的应用。
  10. 一种钾基双离子电池，其特征在于，包括负极、正极、介于正负极之间的隔膜以及电解液；
    所述负极为权利要求1～2任一项所述的预嵌钾负极或权利要求3～8任一项所述的预嵌钾负极的制备方法得到的预嵌钾负极；
    所述正极包括正极集流体和正极材料，正极材料包括正极材料活性物质，正极材料活性物质为能够可逆地插嵌、脱嵌电解液中阴离子的石墨类碳材料；
    所述正极材料活性物质为膨胀石墨。
  11. 权利要求10所述的钾基双离子电池的制备方法，其特征在于，将负极、电解液、隔膜以及正极进行组装，得到钾基双离子电池；
    所述方法包括以下步骤：
    (a)制备钾离子半电池，将钾离子半电池进行恒流充电和/或放电，以设定的放电电量为标准，停止测试后拆解得到预嵌钾负极；
    (b)将步骤(a)得到的预嵌钾负极与电解液、隔膜以及正极进行组装，得到钾基双离子电池。
  12. 一种用电设备，其特征在于，包括权利要求10所述的钾基双离子电池或权利要求11所述的钾基双离子电池的制备方法得到的钾基双离子电池。
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