Negative-electrode-free lithium-potassium dual-ion battery and preparation method thereof

Abstract

The invention provides a negative-electrode-free lithium-potassium dual-ion battery and a preparation method thereof, and belongs to the technical field of secondary batteries. The lithium-potassium dual-ion battery without the negative electrode comprises a positive electrode current collector, a positive electrode active material layer, a diaphragm, a negative electrode current collector and electrolyte which are sequentially stacked, the positive electrode active material layer comprises a lithium-based positive electrode active material; the electrolyte comprises a lithium salt, a potassium salt and an organic solvent. According to the negative-electrode-free lithium-potassium dual-ion battery provided by the invention, the potassium salt is introduced into the electrolyte, so that the low-temperature performance of the battery is effectively improved under the condition that the energy density of the battery is not obviously reduced, and the application temperature range of the battery is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of secondary batteries, and in particular relates to a negative electrode-free lithium-potassium dual-ion battery and a preparation method thereof. Background Art

[0002] At present, the continuous upgrading of global energy consumption has led to the rapid development of renewable energy technology. Driven by the continuous upgrading of energy demand and related energy storage technology, rechargeable secondary batteries have been widely used in large-scale energy storage systems, electric vehicles and portable electronic products due to their advantages such as high energy and power density, high safety, long cycle life and low cost.

[0003] The most common secondary battery is the lithium-ion battery, which works as follows: during the charging process, the lithium ions in the positive electrode material escape into the electrolyte, and the lithium ions in the electrolyte are embedded in the negative electrode to form lithium metal; during the discharge process, the lithium metal in the negative electrode is oxidized to lithium ions, escape from the negative electrode into the electrolyte, and the lithium ions in the electrolyte are embedded in the positive electrode. That is, lithium ions are embedded and extracted back and forth between the positive and negative electrodes. Therefore, this type of secondary battery is also called a "rocking chair" battery.

[0004] Existing lithium-ion batteries generally use graphite as the negative electrode material, and the theoretical specific capacity of graphite is 372mAh / g. With the development of new energy vehicles, the market has higher and higher requirements for the energy density of secondary batteries. Lithium-ion batteries using graphite negative electrodes have gradually been unable to meet application needs, and the energy density of batteries needs to be further improved.

[0005] Lithium metal anode has high theoretical specific capacity (3860mAh / g) and low reduction potential (E Li / Li + :-3.04V vsSHE) and small ion radius can greatly improve the energy density of lithium-ion batteries. However, lithium metal has high chemical and electrochemical reactivity and is easy to react with electrolyte. The continuously consumed electrolyte will corrode lithium metal to form an irreversible solid electrolyte interface. In addition, dendrites are very easy to grow on the surface of lithium metal, which seriously affects the coulombic efficiency and safety of the battery and reduces the cycle life.

[0006] A negative electrode-free secondary battery is a battery that does not contain negative electrode active materials. It is composed of positive electrode current collector / positive electrode active material layer / separator / negative electrode current collector and electrolyte. The negative electrode-free design can reduce the overall weight and volume of the battery and significantly increase the energy density of the battery; since no negative electrode active materials are introduced, the cost can be greatly reduced while simplifying the manufacturing process; in addition, compared with lithium metal batteries, negative electrode-free secondary batteries do not have lithium metal foil, and the limited active lithium can significantly reduce the safety risks of the battery.

[0007] However, the traditional rocking-chair-style anode-free lithium-ion battery cannot achieve stable lithium ion deposition and extraction on the anode side, which makes the coulombic efficiency and cycle performance of this type of battery poor and low safety. Especially under low temperature conditions, the anode-free lithium-ion battery can hardly work, which seriously limits the application of the anode-free lithium-ion battery in a wide temperature range. Summary of the invention

[0008] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a negative electrode-free lithium potassium dual-ion battery and a preparation method thereof. The negative electrode-free lithium potassium dual-ion battery effectively improves the low-temperature performance of the battery and broadens the application temperature range of the battery without significantly reducing the battery energy density.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a negative electrode-free lithium potassium dual ion battery, the negative electrode-free lithium potassium dual ion battery comprising a positive electrode current collector, a positive electrode active material layer, a separator and a negative electrode current collector, and an electrolyte, which are sequentially stacked;

[0011] The positive electrode active material layer includes a lithium-based positive electrode active material;

[0012] The electrolyte includes lithium salt, potassium salt and an organic solvent.

[0013] The negative electrode-free lithium-potassium dual-ion battery provided by the present invention introduces potassium salt into the electrolyte. Since potassium ions have a reduction potential (E K / K + :-2.93V vs SHE、E Li / Li + : -3.04V vs SHE), so during the battery charging process, potassium ions on the negative electrode side can be reduced to potassium metal before lithium ions, and lithium ions in the positive electrode material on the positive electrode side are deintercalated into the electrolyte; during the battery discharging process, potassium metal on the negative electrode side is oxidized to potassium ions, deintercalated into the electrolyte, and lithium ions in the electrolyte on the positive electrode side are intercalated into the positive electrode material. That is, during the charging and discharging process, lithium ions are intercalated / extracted on the positive electrode side, and potassium ions on the negative electrode side are deposited / exintercalated instead of lithium ions. Potassium ions can achieve a stable deposition / deintercalation process at low temperatures, which can effectively improve the low temperature performance of the battery and broaden the application temperature range of the battery.

[0014] In addition, although the reduction potential of potassium ions is higher than that of lithium ions, the negative electrode-free lithium potassium dual ion battery (compared to the negative electrode-free lithium ion battery) will have a certain degree of voltage drop, but this change (only 0.11V) is small, so the energy density of the battery as a whole is less affected. At the same time, the introduction of potassium ions can also enable the battery to have a higher power density. Therefore, the negative electrode-free lithium potassium dual ion battery provided by the present invention also has the advantages of high energy density of negative electrode-free batteries and high power density of potassium ion batteries.

[0015] In some embodiments of the present invention, the positive electrode active material layer further includes a conductive agent and a binder.

[0016] In some embodiments of the present invention, the positive electrode active material layer includes the following components in mass percentage: 65-95% of lithium-based positive electrode active material (for example, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92% or 95%, etc.), 3-25% of conductive agent (for example, 3%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22% or 25%, etc.), and 2-10% of binder (for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc.). However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0017] In some embodiments of the present invention, the lithium-based positive electrode active material is selected from lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), lithium manganese iron phosphate (LiFe x Mn 1-x PO4, 0<x<1) and nickel cobalt lithium manganese oxide ternary material (LiCo x Mn y Ni z O2, x+y+z=1) or a combination of at least two thereof, preferably lithium cobalt oxide (LiCoO2).

[0018] In some embodiments of the present invention, the conductive agent is selected from any one or a combination of at least two of Super P, Ketjen black, acetylene black and carbon nanotubes, preferably Super P.

[0019] In some embodiments of the present invention, the binder is selected from any one of polyvinylidene fluoride, polytetrafluoroethylene and polyolefin binders or a combination of at least two thereof, preferably polyvinylidene fluoride.

[0020] In some embodiments of the present invention, the positive electrode current collector is selected from aluminum foil, carbon-coated aluminum foil, tin foil, titanium foil and stainless steel foil; preferably aluminum foil.

[0021] In some embodiments of the present invention, the separator is a porous polymer film or a glass fiber separator.

[0022] In some embodiments of the present invention, the negative electrode current collector is selected from any one of the following foils that have been or have not been treated with plasma: aluminum foil, carbon-coated aluminum foil, aluminum mesh, carbon-coated aluminum mesh, stainless steel foil, carbon-coated stainless steel foil, stainless steel mesh and carbon-coated stainless steel mesh, preferably carbon-coated aluminum foil treated with plasma.

[0023] In the present invention, after plasma treatment, or carbon coating surface modification, or carbon coating surface modification and plasma treatment, the negative electrode current collector can have a potassium-philic surface, the binding ability of potassium and the negative electrode current collector can be improved, and the nucleation overpotential of potassium deposition can be reduced, potassium can be deposited more smoothly, and the occurrence of side reactions can be minimized and high rate performance can be achieved.

[0024] In the present invention, there is no particular limitation on the plasma treatment and carbon coating surface modification, as long as the potassium affinity of the negative electrode current collector can be improved. As a non-limiting example, the plasma treatment can use methane as the gas medium; the carbon coating surface modification carbon layer can be graphene or carbon nanotubes.

[0025] In some embodiments of the present invention, the lithium salt is selected from any one or a combination of at least two of LiPF6, LiBF4, LiClO4, LiFSI, LiTFSI, LiCF3SO3 and LiNO3, preferably LiPF6.

[0026] In some embodiments of the present invention, the concentration of lithium salt in the electrolyte is 0.5-5 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L, etc.; preferably 0.5-1.5 mol / L; more preferably 1 mol / L. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0027] In some embodiments of the present invention, the potassium salt is selected from any one or a combination of at least two of KPF6, KBF4, KClO4, KFSI, KTFSI, KCF3SO3 and KNO3, preferably KFSI.

[0028] In some embodiments of the present invention, the concentration of potassium salt in the electrolyte is 0.1-1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1 mol / L, etc.; preferably 0.25-0.6 mol / L; more preferably 0.3 mol / L. However, the present invention is not limited to the listed values, and other values ​​not listed in the range are also applicable.

[0029] In some embodiments of the present invention, the organic solvent is selected from any one or a combination of at least two of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, 1,3-dioxolane, dioxane, tetrahydrofuran, propylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, ethyl methyl carbonate, ethylene carbonate and vinylene carbonate, preferably ethylene glycol dimethyl ether.

[0030] In some embodiments of the present invention, the electrolyte includes 0.5-5 mol / L LiPF6, 0.1-1 mol / L KFSI, and the balance ethylene glycol dimethyl ether.

[0031] In the embodiment of the present invention, the electrolyte in the electrolyte is preferably LiPF6 and KFSI, which cooperate with each other to help form a SEI film with low impedance and good stability during the battery charging and discharging process, further improving the battery's cycle performance. If the concentration of LiPF6 is too low, the ion transmission capacity of the electrolyte will be low and the battery internal resistance will be large. If the concentration of KFSI is too low, its effect on improving the low-temperature performance of the battery is weak; if the concentration of KFSI is too high, it is easy to cause the impedance of the SEI film formed during the battery charging and discharging process to be large, and may cause some potassium ions to be embedded / extracted at the positive electrode, affecting the battery's cycle performance.

[0032] The organic solvent in the electrolyte is preferably an ether solvent, and more preferably ethylene glycol dimethyl ether, which helps to improve the stability and uniformity of metal ion deposition on the negative electrode side and further improve the cycle performance of the battery.

[0033] In a second aspect, the present invention provides a method for preparing a negative electrode-free lithium potassium dual-ion battery as described in the first aspect, the preparation method comprising the following steps:

[0034] (1) applying a positive electrode slurry to the surface of a positive electrode current collector, and forming a positive electrode active material layer after the positive electrode slurry is dried;

[0035] (2) Assembling a dry cell according to the stacked structure of the positive electrode current collector, the positive electrode active material layer, the separator and the negative electrode current collector, and obtaining a negative electrode-free lithium potassium dual-ion battery after liquid injection and optional formation.

[0036] In the present invention, the term "optionally forming" means that forming is performed or not performed. For large-capacity batteries, forming is usually required; for small-capacity batteries, forming may not be performed.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The negative electrode-free lithium-potassium dual-ion battery provided by the present invention introduces potassium salt into the electrolyte, and potassium ions can be reduced on the negative electrode side preferentially over lithium ions, that is, during the charge and discharge process, lithium ions are embedded / de-embedded on the positive electrode side, and potassium ions are deposited / de-embedded on the negative electrode side instead of lithium ions, which can effectively improve the low-temperature performance of the battery without significantly reducing the battery energy density and broaden the application temperature range of the battery.

[0039] (2) The negative electrode-free lithium potassium dual-ion battery provided by the present invention uses lithium ions as the energy storage medium on the positive electrode side and potassium ions as the energy storage medium on the negative electrode side. It combines the advantages of high energy density of negative electrode-free batteries and high power density of potassium ion batteries.

[0040] (3) The negative electrode-free lithium potassium dual-ion battery provided by the present invention does not introduce negative electrode active materials, which can reduce the production cost of the battery and simplify the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The cycle performance diagram of the negative electrode-free lithium potassium dual-ion battery provided in Example 1 of the present invention at room temperature and low temperature;

[0042] Figure 2 This is a rate performance diagram of the negative electrode-free lithium-potassium dual-ion battery provided in Example 1 of the present invention at room temperature and low temperature. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementations. It should be understood by those skilled in the art that the specific implementations are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0044] Example 1

[0045] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, comprising a positive electrode current collector, a positive electrode active material layer, a separator and a negative electrode current collector, and an electrolyte, which are stacked in sequence;

[0046] The positive electrode active material layer is composed of 90 wt % lithium cobalt oxide (LiCoO2), 5 wt % Super P and 5 wt % polyvinylidene fluoride.

[0047] The preparation method of the negative electrode-free lithium potassium dual-ion battery described in this embodiment is as follows:

[0048] (1) Preparation of positive electrode sheet

[0049] Weigh 450 mg LiCoO2, 25 mg Super P and grind them thoroughly, add 25 mg polyvinylidene fluoride and a certain amount of N-methylpyrrolidone (NMP), mix well, and obtain positive electrode slurry;

[0050] The positive electrode slurry was coated on the positive electrode current collector aluminum foil and vacuum dried at 120°C for 12 hours, wherein the positive electrode slurry formed a positive electrode active material layer (surface density 5 mg / cm 2 ) to obtain the positive electrode.

[0051] (2) Preparation of negative electrode current collector

[0052] The carbon-coated aluminum foil was placed in a plasma etching cleaning machine, with methane as the gas medium, at a temperature of 600°C and a pressure of 0.3 Pa for 2 minutes;

[0053] The carbon-coated aluminum foil after plasma treatment was vacuum dried at 120° C. for 12 h, and then cut into pieces to obtain the negative electrode current collector I-Al / C of the required size.

[0054] (3) Prepare an electrolyte solution containing 1 mol / L LiPF6 and 0.3 mol / L KFSI in ethylene glycol dimethyl ether.

[0055] (4) Cut the diaphragm into the required size. The diaphragm is Whatman GF / D diaphragm.

[0056] (5) Assemble a battery according to the stacked structure of the positive electrode current collector, the positive electrode active material layer, the separator and the negative electrode current collector, inject electrolyte with an injection coefficient of 4 g / Ah to obtain a negative electrode-free lithium potassium dual-ion battery.

[0057] Example 2

[0058] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from the embodiment 1 in that:

[0059] The positive electrode current collector is stainless steel foil;

[0060] The positive electrode active material layer is composed of 80wt% lithium iron phosphate (LiFePO4), 10wt% Ketjen black and 10wt% polytetrafluoroethylene;

[0061] The negative electrode current collector is a titanium foil treated with plasma (the plasma treatment method is the same as that in Example 1);

[0062] The electrolyte is a dimethyl carbonate / ethylene carbonate solution containing 1 mol / L LiClO4 and 0.5 mol / L KTFSI, and the volume ratio of the solvent dimethyl carbonate to ethylene carbonate is 1:1.

[0063] Example 3

[0064] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from the embodiment 1 in that:

[0065] The positive electrode current collector is tin foil;

[0066] The positive electrode active material layer is composed of 94wt% LiCo 0.2 Mn 0.2 Ni 0.6 O2, 2wt% carbon nanotubes and 4wt% polyvinylidene fluoride;

[0067] The negative electrode current collector is a stainless steel foil treated with plasma (the plasma treatment method is the same as that in Example 1);

[0068] The electrolyte is a 1,3-dioxolane solution containing 1 mol / L LiPF6 and 0.6 mol / L KPF6.

[0069] Example 4

[0070] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from Embodiment 1 in that the electrolyte is a diethylene glycol dimethyl ether solution containing 0.5 mol / L LiBF4 and 1 mol / L KCF3SO3.

[0071] Example 5

[0072] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from Embodiment 1 in that the electrolyte is an ethylene glycol diethyl ether solution containing 2 mol / L LiFSI and 0.2 mol / L KClO4.

[0073] Example 6

[0074] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from Embodiment 1 in that the electrolyte is a tetrahydrofuran solution containing 5 mol / L LiTFSI and 0.1 mol / L KNO3.

[0075] Example 7

[0076] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from Embodiment 1 in that the concentration of KFSI in the electrolyte is 0.06 mol / L.

[0077] Example 8

[0078] This embodiment provides a negative electrode-free lithium potassium dual-ion battery, which is different from Embodiment 1 in that the concentration of KFSI in the electrolyte is 1.5 mol / L.

[0079] Comparative Example 1

[0080] This comparative example provides a negative electrode-free lithium-ion battery, which is different from Example 1 only in that the electrolyte is an ethylene glycol dimethyl ether solution containing 1 mol / L LiPF6.

[0081] Comparative Example 2

[0082] This comparative example provides a negative electrode-free lithium-ion battery, which is different from Example 1 only in that the electrolyte is an ethylene glycol dimethyl ether solution containing 1 mol / L LiPF6 and 0.3 mol / L LiFSI.

[0083] Performance Testing

[0084] (1) Battery cycle performance test

[0085] The batteries provided in the embodiments and comparative examples were subjected to constant current charge and discharge cycle tests at room temperature (25°C) and -40°C, respectively, with a voltage range of 2.5-4.2V and a current density of 0.05C. The first discharge specific capacity and the discharge specific capacity after 100 cycles were recorded, and the discharge capacity retention rate after 100 cycles was calculated as discharge specific capacity at the 100th cycle / first discharge specific capacity × 100%.

[0086] (2) Battery rate performance test

[0087] The batteries provided in the embodiments and comparative examples were charged and discharged for 5 cycles at current densities of 0.05C, 0.1C, and 0.2C at room temperature (25°C) and -40°C, respectively, and at a voltage range of 2.5-4.2V. The charge and discharge cycles were then continued at a current density of 0.05C for 5 cycles. The charge and discharge specific capacity of each cycle was recorded, and the coulombic efficiency was calculated as discharge specific capacity / charge specific capacity × 100%.

[0088] The cycle performance and rate performance test results of the battery provided in Example 1 are as follows: Figure 1 , Figure 2 The cycle performance data of the batteries provided in the embodiments and comparative examples are shown in Table 1.

[0089] Table 1

[0090]

[0091]

[0092] from Figure 1 It can be seen that the negative electrode-free lithium potassium dual-ion battery provided in Example 1 has a first discharge specific capacity of 142 mAh / g and 121 mAh / g at a current density of 0.05 C at room temperature 25°C and low temperature -40°C, respectively, and a capacity retention rate of 78% and 56% after 100 cycles, respectively. This shows that the negative electrode-free lithium potassium dual-ion battery provided by the present invention has good cycle performance at both room temperature and low temperature.

[0093] from Figure 2 It can be seen that the negative electrode-free lithium potassium dual-ion battery provided in Example 1 can maintain a discharge capacity of more than 120 mAh / g at different current densities at 25°C, and a discharge capacity of more than 85 mAh / g at different current densities at -40°C. This shows that the negative electrode-free lithium potassium dual-ion battery provided by the present invention has excellent rate performance at both room temperature and low temperature.

[0094] As can be seen from Table 1, compared with Example 1, no potassium salt is added to the electrolyte of Comparative Example 1, and Comparative Example 2 replaces the potassium salt in the electrolyte with the same molar amount of lithium salt. Although the first discharge specific capacity of the negative electrode-free lithium ion battery provided by the two at room temperature is slightly higher than that of the negative electrode-free lithium potassium dual ion battery provided in Example 1, the first discharge specific capacity at -40°C is greatly reduced, and 100 charge and discharge cycles cannot be completed. It shows that the negative electrode-free lithium potassium dual ion battery provided by the present invention effectively improves the low temperature performance of the battery without significantly reducing the battery energy density.

[0095] Compared with Example 1, the lithium salt concentration in the electrolyte of Example 5 and Example 6 is relatively high and the potassium salt concentration is relatively low, so the low-temperature cycle performance of the battery is reduced, but it is still better than the battery without adding potassium salt to the electrolyte (Comparative Examples 1 and 2).

[0096] Compared with Example 1, the concentration of potassium salt in the electrolyte of Example 7 is relatively low, resulting in a low low-temperature first discharge capacity of the battery and poor low-temperature cycle performance; the concentration of potassium salt in the electrolyte of Example 8 is relatively high, resulting in a decrease in the first discharge capacity of the battery and a decrease in the cycle performance.

[0097] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A negative electrode-free lithium potassium dual-ion battery, characterized in that: The negative electrode-free lithium potassium dual ion battery comprises a positive electrode current collector, a positive electrode active material layer, a separator and a negative electrode current collector, and an electrolyte, which are stacked in sequence; The positive electrode active material layer includes a lithium-based positive electrode active material; The electrolyte includes lithium salt, potassium salt and an organic solvent.

2. The negative electrode-free lithium potassium dual-ion battery according to claim 1, characterized in that: The positive electrode active material layer also includes a conductive agent and a binder; Preferably, the positive electrode active material layer comprises the following components in percentage by mass: 65-95% of lithium-based positive electrode active material, 3-25% of conductive agent and 2-10% of binder.

3. The negative electrode-free lithium potassium dual-ion battery according to claim 2, characterized in that: The lithium-based positive electrode active material is selected from any one or a combination of at least two of lithium cobalt oxide, lithium iron phosphate, lithium iron manganese phosphate and nickel cobalt lithium manganese oxide ternary materials, preferably lithium cobalt oxide; Preferably, the conductive agent is selected from any one or a combination of at least two of Super P, Ketjen black, acetylene black and carbon nanotubes, preferably Super P; Preferably, the binder is selected from any one of polyvinylidene fluoride, polytetrafluoroethylene and polyolefin binders or a combination of at least two thereof, preferably polyvinylidene fluoride.

4. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 3, characterized in that: The positive electrode current collector is selected from aluminum foil, carbon-coated aluminum foil, tin foil, titanium foil and stainless steel foil; preferably aluminum foil.

5. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 4, characterized in that: The separator is a porous polymer film or a glass fiber separator.

6. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 5, characterized in that: The negative electrode current collector is selected from any one of the following foils that have been or have not been treated with plasma: aluminum foil, carbon-coated aluminum foil, aluminum mesh, carbon-coated aluminum mesh, stainless steel foil, carbon-coated stainless steel foil, stainless steel mesh and carbon-coated stainless steel mesh, preferably carbon-coated aluminum foil treated with plasma.

7. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 6, characterized in that: The lithium salt is selected from any one or a combination of at least two of LiPF6, LiBF4, LiClO4, LiFSI, LiTFSI, LiCF3SO3 and LiNO3, preferably LiPF6; Preferably, the concentration of lithium salt in the electrolyte is 0.5-5 mol / L, preferably 0.5-1.5 mol / L.

8. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 7, characterized in that: The potassium salt is selected from any one or a combination of at least two of KPF6, KBF4, KClO4, KFSI, KTFSI, KCF3SO3 and KNO3, preferably KFSI; Preferably, the concentration of potassium salt in the electrolyte is 0.1-1 mol / L, preferably 0.25-0.6 mol / L.

9. The negative electrode-free lithium potassium dual-ion battery according to any one of claims 1 to 8, characterized in that: The organic solvent is selected from any one or a combination of at least two of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, 1,3-dioxolane, dioxane, tetrahydrofuran, propylene carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, ethyl methyl carbonate, ethylene carbonate and vinylene carbonate, preferably ethylene glycol dimethyl ether.

10. A method for preparing a negative electrode-free lithium potassium dual-ion battery as claimed in any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) applying a positive electrode slurry to the surface of a positive electrode current collector, and forming a positive electrode active material layer after the positive electrode slurry is dried; (2) Assembling a dry cell according to the stacked structure of the positive electrode current collector, the positive electrode active material layer, the separator and the negative electrode current collector, and obtaining a negative electrode-free lithium potassium dual-ion battery after liquid injection and optional formation.

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