Flame-retardant electrolyte for potassium metal battery and potassium metal battery

Abstract

This invention proposes a novel flame-retardant electrolyte for potassium metal batteries and a potassium metal battery itself. The flame-retardant electrolyte comprises a potassium salt, an organic solvent, and an additive; the organic solvent includes a phosphate ester; the additive includes potassium bis(fluorosulfonyl)imide, and the concentration of potassium bis(fluorosulfonyl)imide in the organic solvent is 0.01~0.2 mol / L. The electrolyte system of this invention exhibits structural stability, safety, reliability, and excellent cycle performance, providing an effective solution for the practical application of potassium metal batteries.

Description

Technical Field

[0001] This invention belongs to the field of potassium metal battery technology, specifically relating to a flame-retardant electrolyte for potassium metal batteries and a potassium metal battery suitable for potassium-based basal oxide cathode material systems. Background Technology

[0002] With the increasing demand for large-scale energy storage systems, the development of novel electrochemical energy storage technologies that are abundant in resources and low in cost has become a research hotspot. Among numerous candidate systems, potassium metal batteries have attracted much attention due to their unique advantages. Potassium is far more abundant in the Earth's crust than lithium and is widely distributed, which reduces the cost of battery raw materials. Meanwhile, potassium's redox potential (… Potassium metal batteries (2.93 V vs. SHE) are similar to lithium, giving them the potential to achieve high energy density.

[0003] In the exploration of constructing high-performance potassium metal batteries, the selection of cathode materials is crucial. Layered transition metal oxides (LMOs) have shown significant application potential due to their high theoretical energy density and relatively simple synthesis process. However, the performance of LMO cathodes in actual battery environments has fallen far short of theoretical expectations. The core bottleneck lies in the complex and unstable chemical and electrochemical reactions at the electrode-electrolyte interface. During high-voltage charging, continuous side reactions occur between the highly active cathode surface and conventional electrolyte components, resulting in a porous and unevenly composed cathode electrolyte interphase (CEI) film that cannot effectively protect the cathode material. This, in turn, leads to the dissolution of transition metal ions, lattice oxygen loss, and irreversible structural phase transitions, manifesting as significant capacity decay, average voltage drop, and increased polarization during battery cycling. Currently, commercially available electrolyte systems (such as KPF6 electrolyte based on carbonate solvents) cannot meet the stringent requirements of LMO cathodes for interfacial stability, and highly adaptable functionalized electrolytes remain scarce.

[0004] Beyond interface compatibility challenges, the inherent flammability of the electrolyte itself severely restricts the safe development and practical application of potassium metal batteries, especially those based on high-energy-density cathodes. Currently, mainstream organic electrolyte solvents have low flash points and high volatility, making them highly flammable under abusive conditions such as heat and electricity. When combined with highly active potassium metal anodes, the safety risks are further amplified. Therefore, to further promote the development of potassium metal batteries, it is necessary to design and develop a novel electrolyte system that balances interface stability and intrinsic flame retardancy to improve the overall safety performance and cycle life of potassium metal batteries. Summary of the Invention

[0005] To address the technical problems of poor interfacial stability and poor thermal safety of existing flame-retardant electrolytes for potassium metal batteries, this invention proposes a flame-retardant electrolyte for potassium metal batteries and a potassium metal battery.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a flame-retardant electrolyte for potassium metal batteries, comprising a potassium salt, an organic solvent, and an additive; the organic solvent comprises a phosphate ester; the additive comprises potassium bis(fluorosulfonyl)imide (KFSI), wherein the concentration of potassium bis(fluorosulfonyl)imide in the organic solvent is 0.01~0.2 mol / L.

[0007] Preferably, the phosphate ester is one or a combination of two of tris(2,2,2-trifluoroethyl) phosphate (TFP) and triethyl phosphate (TEP).

[0008] Furthermore, the volume ratio of tris(2,2,2-trifluoroethyl) phosphate to triethyl phosphate is 1:0 to 0:1.

[0009] Preferably, the additive further includes 1,3-propanesulfonate lactone (PS) and / or vinyl sulfate (DTD).

[0010] Furthermore, the mass of the 1,3-propanesulfonate lactone accounts for 0.1 wt% to 5 wt% of the total mass of the potassium salt and organic solvent, more preferably 0.2 wt% to 2 wt%.

[0011] Furthermore, the mass of the vinyl sulfate accounts for 0.1 wt% to 5 wt% of the total mass of the potassium salt and organic solvent, more preferably 0.2 wt% to 2 wt%.

[0012] Furthermore, the concentration of the potassium difluorosulfonamide in the organic solvent is more preferably 0.02~0.1 mol / L.

[0013] Preferably, the potassium salt is potassium bis(trifluoromethylsulfonyl)imide or potassium hexafluorophosphate.

[0014] Furthermore, the concentration of the potassium salt in the organic solvent is 0.5~2 mol / L.

[0015] Secondly, the present invention provides a potassium metal battery, comprising a positive electrode, a negative electrode, and an electrolyte located between the positive electrode and the negative electrode, wherein the electrolyte is a flame-retardant electrolyte for potassium metal batteries as described above.

[0016] The active material of the positive electrode is a Prussian blue-based material, a layered transition metal oxide, a polyanionic compound, or an organic electrode material. The active material of the negative electrode is potassium metal.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention uses phosphate esters as the core solvent for flame-retardant electrolytes in potassium metal batteries. On one hand, phosphate esters decompose upon combustion, generating phosphorus-containing free radicals such as PO· and HPO·. These free radicals inhibit combustion by capturing hydrogen free radicals (H·) and hydroxyl free radicals (OH·), thus improving the overall stability and safety of the battery system. On the other hand, the additives introduced in this invention induce solvent conversion, constructing a dense and uniform inorganic interfacial film on the positive electrode surface. Unlike high-dose KFSI, which, as the main salt, generates a large amount of KF to stabilize the interface through decomposition, the introduction of trace amounts of potassium difluorosulfonyl imide in this invention achieves this through FSI... Entering the solvation shell and participating in coordination raises the highest occupied molecular orbital (HOMO) energy level of the complex, making the phosphate ester molecule in the complex more prone to decomposition under high pressure. The lower bond energy C–O molecule, after breaking, leaves behind PO4. x The framework combines with potassium ions to transform into inorganic phosphate, which is adsorbed onto the positive electrode surface, constructing a phosphorus-rich inorganic interfacial film that enhances the chemical and mechanical stability of the interfacial film. This phosphorus-rich inorganic interfacial film effectively passivates the electrode, preventing the continued occurrence of side reactions between the electrode and the electrolyte, thereby improving battery stability. The electrolyte system of this invention features structural stability, safety, reliability, and excellent cycle performance, providing an effective solution for the practical application of potassium metal batteries. Furthermore, the electrolyte system design of this invention balances cost-effectiveness and industrialization prospects; the selected components have controllable costs and stable supply, providing a solid foundation for large-scale production and commercial application.

[0018] Furthermore, this invention introduces film-forming additives such as vinyl sulfate and 1,3-propanesulfonate lactone, which further stabilize the interfacial film formed on the cathode surface, enhance the mechanical toughness of the interfacial film under long-term cycling, and improve the cycle life of the battery. Therefore, the composite interfacial film constructed by the combination of multiple additives in this invention reshapes the interfacial chemical environment under high pressure, suppresses high-pressure oxidation side reactions and gas escape, and overcomes the problem of interfacial failure under high pressure and long-term cycling.

[0019] The research results of this invention show that when the aforementioned flame-retardant electrolyte for potassium metal batteries is combined with K... 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode assembly of the half-cell provides a discharge specific capacity of nearly 110 mA h / g when operating at a 0.5 C rate and a voltage range of 1.5–4 V. It also provides a reversible discharge capacity exceeding 100 mA h / g during cycling at a 1 C rate, and retains over 80% of its capacity after 300 cycles at 1 C. Furthermore, it exhibits excellent cycle stability and interface stability under a stable operating voltage of 4 V. This demonstrates that the battery assembled using the electrolyte described in this invention possesses high safety, high discharge specific capacity, and excellent cycle stability. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The first three charge-discharge curves of the potassium metal battery at a 0.5C rate corresponding to Example 1 of the present invention are shown.

[0022] Figure 2 The diagram shows the cycle performance of the potassium metal batteries corresponding to Example 1 and Comparative Example 1 of this invention at a 1C rate.

[0023] Figure 3 This is a test diagram of the flame retardant ability of the electrolyte in Embodiment 1 of the present invention. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0026] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0027] This invention provides a flame-retardant electrolyte for potassium metal batteries, achieving flame retardancy against potassium-based substrate cathode materials within a working voltage window of 1.5~4 V. 0.4 Li 0.1 Fe 0.1 Mn 0.8The good compatibility with O2. To verify the actual performance of the electrolyte proposed in this invention in potassium metal batteries, K was selected. 0.4 Li 0.1 Fe 0.1 Mn 0.8 O2 cathode material was used to assemble coin half-cells for testing. Electrolyte preparation and battery assembly were both performed in an argon glove box with oxygen and water content both below 0.1 ppm. The battery model was CR2032. After 4 hours of resting, the assembled batteries were subjected to constant current charge-discharge tests in the voltage range of 1.5–4.0 V using a Newway battery testing system to evaluate their electrochemical performance.

[0028] Example 1 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0029] The potassium salt is bis(trifluoromethylsulfonyl)imide potassium, and the concentration of the potassium salt in the organic solvent is 0.5 mol / L; the organic solvent is tris(2,2,2-trifluoroethyl) phosphate; the additive is a combination of bis(trifluoromethylsulfonyl)imide potassium and vinyl sulfate, the concentration of bis(trifluoromethylsulfonyl)imide potassium in the organic solvent is 0.025 mol / L, and the amount of vinyl sulfate added is 0.2 wt% of the electrolyte mass.

[0030] The preparation method of the electrolyte includes the following steps: First, the organic solvent is dehydrated using a molecular sieve. Then, a certain amount of organic solvent is taken out, and potassium bis(trifluoromethanesulfonyl)imide is added to a concentration of 0.5 mol / L. Then, potassium bis(trifluoromethanesulfonyl)imide is added to a concentration of 0.025 mol / L and 0.2 wt% vinyl sulfate is added sequentially. Then, the mixture is stirred at room temperature using a magnetic stirrer until the salt is dissolved. All operations are completed in a glove box.

[0031] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. For example... Figure 1 As shown, the assembled battery has a discharge specific capacity of 110.91 mA h / g at a 0.5 C rate at room temperature, and retains 80.08% of its capacity after 200 cycles at 0.5 C. Figure 2 As shown, the assembled battery retains 81.54% of its capacity after 300 cycles at 1 C.

[0032] Example 2 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0033] The potassium salt is bis(trifluoromethylsulfonyl)imide potassium, and the concentration of the potassium salt in the organic solvent is 0.5 mol / L; the organic solvent is tris(2,2,2-trifluoroethyl) phosphate; the additive is bis(fluorosulfonyl)imide potassium, and the concentration of bis(fluorosulfonyl)imide potassium in the organic solvent is 0.025 mol / L.

[0034] The preparation method of the electrolyte is the same as in Example 1.

[0035] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 108.17 mA h / g at room temperature and a capacity retention of 76.01% after 300 cycles at 1 C.

[0036] Comparing Example 1 and Example 2, it can be seen that the cycle stability of the battery is improved after adding DTD, indicating that the introduction of film-forming additives effectively improves battery stability.

[0037] Example 3 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0038] The potassium salt is potassium bis(trifluoromethylsulfonyl)imide, and the concentration of the potassium salt in the organic solvent is 0.5 mol / L. The organic solvent is a combination of tris(2,2,2-trifluoroethyl) phosphate and triethyl phosphate, with a volume ratio of 4:3. The additive is a combination of vinyl sulfate and potassium bis(fluorosulfonyl)imide, with the amount of vinyl sulfate added being 0.2 wt% of the electrolyte mass, and the concentration of potassium bis(fluorosulfonyl)imide in the organic solvent being 0.025 mol / L.

[0039] The preparation method of the electrolyte is the same as in Example 1.

[0040] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 98 mA h / g at 0.5 C rate at room temperature, and retained a specific capacity of 93.88 mA h / g after 200 cycles, with a capacity retention of 95.79%.

[0041] Comparing Examples 1 and 3, it can be seen that the discharge specific capacity of the battery decreased after the introduction of TEP solvent, which may be related to the reduction of ion transport number in the electrolyte.

[0042] Example 4 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0043] The potassium salt is potassium bis(trifluoromethylsulfonyl)imide, with a concentration of 0.5 mol / L in the organic solvent. The organic solvent is a combination of tris(2,2,2-trifluoroethyl) phosphate and triethyl phosphate, with a volume ratio of 4:3. The additive is potassium bis(fluorosulfonyl)imide, with a concentration of 0.025 mol / L in the organic solvent.

[0044] The preparation method of the electrolyte is the same as in Example 1.

[0045] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 87.56 mA h / g at 0.5 C rate at room temperature, and retained a specific capacity of 74.15 mA h / g after 150 cycles, with a capacity retention of 84.69%.

[0046] Example 5 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0047] The potassium salt is potassium bis(trifluoromethylsulfonyl)imide, and its concentration in the organic solvent is 0.5 mol / L. The organic solvent is a combination of tris(2,2,2-trifluoroethyl) phosphate and triethyl phosphate, with a volume ratio of 4:3. The additive is a combination of vinyl sulfate and potassium bis(fluorosulfonyl)imide, with the amount of vinyl sulfate added being 0.6 wt% of the electrolyte mass, and the concentration of potassium bis(fluorosulfonyl)imide in the organic solvent being 0.025 mol / L.

[0048] The preparation method of the electrolyte is the same as in Example 1.

[0049] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 95.07 mA h / g at 0.5 C rate at room temperature, and a specific capacity of 73.74 mA h / g after 130 cycles, with a capacity retention of 77.56%.

[0050] Comparing Examples 3-5, it can be seen that compared with no vinyl sulfate, a small amount of vinyl sulfate can improve battery performance. However, when a large amount of vinyl sulfate is added, the battery capacity retention rate decreases. This indicates that the amount of vinyl sulfate added should not be too much and should be controlled at a low level.

[0051] Example 6 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0052] The potassium salt is potassium bis(trifluoromethylsulfonyl)imide, with a concentration of 0.5 mol / L in the organic solvent. The organic solvent is a combination of tris(2,2,2-trifluoroethyl) phosphate and triethyl phosphate, with a volume ratio of 4:3. The additive is a combination of 1,3-propanesulfonate lactone and potassium bis(trifluoromethylsulfonyl)imide, with the amount of 1,3-propanesulfonate lactone added being 0.2 wt% of the electrolyte mass, and the concentration of potassium bis(trifluoromethylsulfonyl)imide in the organic solvent being 0.025 mol / L.

[0053] The preparation method of the electrolyte is the same as in Example 1.

[0054] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 80.25 mA h / g at room temperature and a specific capacity of 79.51 mA h / g after 140 cycles.

[0055] Comparing Examples 3 and 6, it can be seen that the discharge specific capacity of the battery with PS as the film-forming additive is reduced, which may be related to the decrease in ion transport number in the electrolyte.

[0056] Comparative Example 1 The flame-retardant electrolyte for potassium metal batteries provided in this comparative example includes potassium salts and organic solvents.

[0057] The potassium salt is bis(trifluoromethylsulfonyl)imide potassium, and the concentration of the potassium salt in the organic solvent is 0.5 mol / L; the organic solvent is tris(2,2,2-trifluoroethyl) phosphate.

[0058] The preparation method of the electrolyte is the same as in Example 1.

[0059] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 108.29 mA h / g at room temperature and a discharge specific capacity of 48.93 mA h / g after 300 cycles at 1 C, with a capacity retention of 45.19%.

[0060] Comparative Example 2 The flame-retardant electrolyte for potassium metal batteries provided in this embodiment includes potassium salts, organic solvents, and additives.

[0061] The potassium salt is bis(trifluoromethanesulfonyl)imide potassium, and the concentration of the potassium salt in the organic solvent is 0.5 mol / L. The organic solvent is tris(2,2,2-trifluoroethyl) phosphate. The additive is vinyl sulfate, and the amount of vinyl sulfate added is 0.2 wt% of the electrolyte mass.

[0062] The preparation method of the electrolyte is the same as in Example 1.

[0063] The above electrolyte and K 0.4 Li 0.1 Fe 0.1 Mn 0.8 The O2 cathode was assembled into a CR2032 coin cell in an argon-filled glove box, and its electrochemical performance was tested. The assembled cell had a discharge specific capacity of 90.81 mA h / g at 1 C rate at room temperature, and a specific capacity of 58.04 mA h / g after 300 cycles, with a capacity retention of 53.36%.

[0064] Comparing Example 1, Comparative Example 1, and Comparative Example 2, it can be seen that although the capacity retention rate of the battery in Comparative Example 2 was improved compared to that in Comparative Example 1 after the addition of ethylene sulfate, the improvement was limited. In contrast, after further adding potassium bisfluorosulfonylimide to the electrolyte in Example 1, the cycle stability of the prepared battery was significantly improved. This indicates that the inorganic phosphate products induced by the potassium bisfluorosulfonylimide additive play a significant role in improving interfacial stability.

[0065] Figure 2The cycling stability data for Example 1 and Comparative Example 1 show that the stability of the battery in Example 1 is significantly better than that in Comparative Example 1. This indicates that the inorganic-organic composite interface film synergistically constructed by trace amounts of KFSI and DTD effectively inhibits the continuous oxidative decomposition of the electrolyte and interfacial side reactions under high pressure, and achieves the stable reconstruction of the interfacial chemical environment.

[0066] Figure 3 This is a test diagram of the flame retardancy of the electrolyte in Example 1. The white disc is the GFD separator commonly used in batteries. The electrolyte to be tested was dropped onto the separator and fully wetted. It can be seen that no fire occurred after contact with an open flame, demonstrating good flame retardancy.

[0067] In summary, by comparing the experimental results of the above embodiments, it can be seen that the electrolyte exhibits excellent electrochemical performance when using potassium bis(trifluoromethanesulfonyl)imide as the potassium salt, tris(2,2,2-trifluoroethyl) phosphate as the organic solvent, and potassium bis(fluoromethanesulfonyl)imide and vinyl sulfate as additives. Specifically, when the potassium salt concentration is 0.5 mol / L, the concentration of potassium bis(fluoromethanesulfonyl)imide additive is 0.025 mol / L, and the proportion of vinyl sulfate additive is 0.2 wt%, the electrolyte exhibits excellent electrochemical performance compared to K... 0.4 Li 0.1 Fe 0.1 Mn 0.8 Potassium metal batteries assembled with an O2 cathode exhibit the best performance. This performance advantage is attributed to the additive potassium bis(fluorosulfonyl)imide, which induces solvent conversion to produce inorganic phosphates that form a film on the cathode surface, thereby creating a phosphorus-rich inorganic interfacial film. This phosphorus-rich inorganic interfacial film effectively prevents electron tunneling and improves interfacial stability. Simultaneously, the introduction of film-forming additives further enhances the stability of the interfacial film and reduces side reactions between the electrode material and the electrolyte.

[0068] Finally, it should be emphasized that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A flame-retardant electrolyte for potassium metal batteries, characterized in that, It includes potassium salt, organic solvent and additives; the organic solvent includes phosphate ester, the additive includes potassium difluorosulfonyl imide, and the concentration of potassium difluorosulfonyl imide in the organic solvent is 0.01~0.2 mol / L.

2. The flame-retardant electrolyte for potassium metal batteries according to claim 1, characterized in that, The phosphate ester is one or a combination of two of tris(2,2,2-trifluoroethyl) phosphate and triethyl phosphate.

3. The flame-retardant electrolyte for potassium metal batteries according to claim 2, characterized in that, The volume ratio of tris(2,2,2-trifluoroethyl) phosphate to triethyl phosphate is 1:0 to 0:

1.

4. The flame-retardant electrolyte for potassium metal batteries according to claim 1, characterized in that, The additives also include 1,3-propanesulfonate lactone and / or vinyl sulfate.

5. The flame-retardant electrolyte for potassium metal batteries according to claim 4, characterized in that, The mass of the 1,3-propanesulfonate lactone is 0.1 wt% to 5 wt% of the electrolyte mass.

6. The flame-retardant electrolyte for potassium metal batteries according to claim 4, characterized in that, The mass of the ethylene sulfate is 0.1 wt% to 5 wt% of the electrolyte mass.

7. The flame-retardant electrolyte for potassium metal batteries according to claim 1, characterized in that, The potassium salt is potassium bis(trifluoromethylsulfonyl)imide or potassium hexafluorophosphate.

8. The flame-retardant electrolyte for potassium metal batteries according to claim 1, characterized in that, The concentration of the potassium salt in the organic solvent is 0.5~2 mol / L.

9. A potassium metal battery, characterized in that, It includes a positive electrode, a negative electrode, a membrane disposed between the positive electrode and the negative electrode, and an electrolyte located between the positive electrode and the membrane; the electrolyte is the electrolyte according to any one of claims 1 to 8.

10. The potassium metal battery according to claim 9, characterized in that, The active material of the positive electrode is a Prussian blue-based material, a layered transition metal oxide, a polyanionic compound, or an organic electrode material, and the active material of the negative electrode is potassium metal.

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