Electrolyte, preparation method thereof, potassium ion battery and application

Abstract

This application provides an electrolyte and its preparation method, a potassium-ion battery, and its application. The electrolyte includes a potassium salt, a cationic additive, and a solvent; the cationic additive includes Al. 3+ Fe 3+ Ce 3+ Cr 3+ In 3+ Zr 4+ VO 2+ The electrolyte contains at least one of the following cations: trifluoromethanesulfonate, nitrate, sulfate, and chloride; the solvent includes water. By adding a cationic additive within the scope of this application to the electrolyte, it fills the vacancies caused by the dissolution of transition metal ions in the positive electrode active material during discharge. The metal cations in the cationic additive form stable coordination bonds with the anions in the structure of the positive electrode active material, and the cationic additive can form an interface phase rich in inorganic matter on the surface of the positive electrode, thereby inhibiting the continuous dissolution of transition metal ions in the positive electrode active material and improving the cycle performance of the potassium-ion battery.

Description

Technical Field

[0001] This application relates to the field of electrochemical technology, specifically to an electrolyte and its preparation method, a potassium-ion battery, and its applications. Background Technology

[0002] With the large-scale application of renewable energy and the increasing demand for grid-scale energy storage, the development of highly safe and long-life energy storage technologies has become a research hotspot. Aqueous potassium-ion batteries, due to their advantages such as using non-flammable aqueous electrolytes, abundant potassium resources, and high ionic conductivity, have become strong contenders for the next generation of large-scale energy storage technologies.

[0003] Electrolytes, acting as the "blood" of a battery, play a decisive role in its cycle life, energy density, and safety. Currently, research on electrolytes for aqueous potassium-ion batteries mainly focuses on high-concentration water-in-salt (WIS) systems. By increasing the salt concentration (>20 mol / L) to reduce the free water content, the electrochemical stability window is widened from approximately 2 V in traditional dilute solutions to around 3 V. However, when applied to aqueous potassium-ion batteries, their cycle stability remains poor, limiting their practical application. Therefore, developing a novel electrolyte system capable of achieving ultra-long cycle stability is of great significance for promoting the practical application of aqueous potassium-ion batteries. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art. Therefore, one objective of this application is to provide an electrolyte and its preparation method, a potassium-ion battery, and its application, to suppress the continuous dissolution of transition metal ions from the positive electrode active material and improve the cycle performance of the potassium-ion battery.

[0005] A first aspect of this application provides an electrolyte comprising a potassium salt, a cationic additive, and a solvent; said cationic additive comprising Al 3+ Fe 3+ Ce 3+ Cr 3+ In 3+ Zr 4+ VO 2+ The solvent includes at least one of the following: at least one trifluoromethanesulfonate, nitrate, sulfate, and chloride corresponding to at least one cation; the solvent includes water.

[0006] In some embodiments of this application, the concentration of the cationic additive in the electrolyte is 0.1 mol / L to 2 mol / L; preferably, the concentration of the cationic additive is 0.2 mol / L to 1 mol / L; more preferably, the concentration of the cationic additive is 0.2 mol / L to 0.5 mol / L.

[0007] In some embodiments of this application, the cationic additive includes at least one selected from Al(CF3SO3)3, Fe(CF3SO3)3, Ce(CF3SO3)3, In(CF3SO3)3, Al(NO3)3, Fe(NO3)3, Ce(NO3)3, Cr(NO3)3, In(NO3)3, Zr(NO3)4, Al2(SO4)3, Fe2(SO4)3, Ce2(SO4)3, Cr2(SO4)3, In2(SO4)3, Zr(SO4)2, VOSO4, AlCl3, FeCl3, CeCl3, CrCl3, InCl3, and ZrCl4.

[0008] In some embodiments of this application, the concentration of the potassium salt in the electrolyte is 10 mol / L to 30 mol / L.

[0009] In some embodiments of this application, the potassium salt includes at least one of potassium trifluoromethanesulfonate, potassium difluorosulfonamide, potassium acetate, and potassium trifluoroacetate.

[0010] In some embodiments of this application, the solvent further includes an organic solvent, which satisfies at least one of the following conditions: (1) The organic solvent includes at least one of carbonate solvents, phosphate solvents, alcohol solvents, amide solvents, and sulfone solvents; (2) In the solvent, the volume ratio of the organic solvent to the water is 0:1 to 10:1.

[0011] The second aspect of this application provides a method for preparing the electrolyte provided in the first aspect of this application, comprising: stirring and dissolving the potassium salt, the cationic additive and the solvent at 30°C to 70°C to obtain a first solution; cooling the first solution to room temperature and bubbling it with an inert gas to obtain the electrolyte.

[0012] In some embodiments of this application, the preparation method satisfies at least one of the following conditions: (1) The stirring and dissolving time is 0.5 h to 2 h; (2) The inert gas includes argon or nitrogen; (3) The bubbling treatment time is 0.5 h to 1 h; (4) The ventilation rate of the bubbling treatment is 2 mL / min to 10 mL / min.

[0013] A third aspect of this application provides a potassium-ion battery, which includes the electrolyte provided in the first aspect of this application or the electrolyte prepared by the method provided in the second aspect of this application.

[0014] In some embodiments of the present application, the potassium ion battery includes a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a Prussian blue analogue. The chemical formula of the Prussian blue analogue is K 2-x M[Fe(CN)6] 1-y ·zH2O, where M includes at least one of Mn, Fe, Cu, Ni, Co, and Zn, 0 < x < 1, 0 < y < 1, 0 < z < 1; the negative electrode plate includes a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes at least one of an organic material and a polyanion compound. Preferably, the organic material includes at least one of 3,4,9,10-perylene tetracarboxylic diimide and 1,4,5,8-naphthalene tetracarboxylic anhydride, and the polyanion compound includes potassium titanium phosphate.

[0015] In some embodiments of the present application, the positive electrode current collector includes at least one of a titanium mesh, a carbon cloth, a carbon felt, and a graphite paper; the negative electrode current collector includes at least one of a carbon-coated aluminum foil, a carbon felt, a graphite paper, and a carbon-coated copper foil.

[0016] The fourth aspect of the present application provides an application of the potassium ion battery provided in the third aspect of the present application in an energy storage system.

[0017] Advantages of the present application: The present application provides an electrolyte and its preparation method, a potassium ion battery and an application. The electrolyte includes a potassium salt, a cationic additive, and a solvent; the cationic additive includes at least one of trifluoromethanesulfonates, nitrates, sulfates, and chlorides corresponding to cations of Al 3+ , Fe 3+ , Ce 3+ , Cr 3+ , In 3+ , Zr 4+ , VO 2+ ; the solvent includes water. By adding a cationic additive within the scope of the present application to the electrolyte, it fills the vacancy of the transition metal ion dissolution in the positive electrode active material in-situ during the discharge process of the potassium ion battery. The metal cations in the cationic additive form stable coordination bonds with the anions in the structure of the positive electrode active material, and the cationic additive can form an inorganic-rich interfacial phase on the surface of the positive electrode plate, thereby inhibiting the continuous dissolution of transition metal ions in the positive electrode active material and improving the cycle performance of the potassium ion battery.

[0018] Of course, it is not necessary for any product or method implementing the present application to achieve all the above-mentioned advantages simultaneously. Attached Figure Description

[0019] Figure 1 The graph shows the results of ICP-OES testing of the manganese and aluminum content of the electrolyte in the initial state of Example 1, the electrolyte after the first charge of the three-electrode system, and the electrolyte after the first discharge.

[0020] Figure 2 The graph shows the results of ICP-OES testing of the manganese and aluminum content of the electrolyte in the initial state of Example 1, as well as the electrolyte after the first discharge, the fourth discharge, the eighth discharge, the tenth discharge, and the twentieth discharge of the three-electrode system.

[0021] Figure 3 The graph shows the results of ICP-OES testing of the manganese content in the electrolyte of Comparative Example 1 in its initial state, as well as in the electrolyte after the first discharge, fourth discharge, eighth discharge, tenth discharge, and twentieth discharge of the three-electrode system.

[0022] Figure 4 The results are the Raman spectra of the initial KMnPBA positive electrode prepared in Example 1 and the Raman spectra of the KMnPBA positive electrode after 20 cycles of three-electrode charge-discharge testing. Detailed Implementation

[0023] The embodiments of this application are described in detail below, with examples of the embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0024] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0025] In aqueous potassium-ion batteries, WIS electrolytes still face numerous challenges. The positive electrode active material is prone to continuous dissolution of transition metal ions in aqueous electrolytes, leading to structural collapse and severe capacity decay, becoming a core bottleneck restricting the cycle life of aqueous potassium-ion batteries. Related technologies mainly involve introducing functional additives into the electrolyte, such as film-forming additives and chelating agents, to slow dissolution by forming a protective layer on the surface of the positive electrode or complexing transition metal ions. However, existing additives are mostly passive film-forming agents, making it difficult to achieve in-situ repair of the crystal structure of the positive electrode active material, and thus their effect on inhibiting the dissolution of transition metal ions is limited.

[0026] A first aspect of this application provides an electrolyte comprising a potassium salt, a cationic additive, and a solvent; said cationic additive comprising Al 3+ Fe 3+ Ce 3+ Cr 3+ In 3+ Zr 4+ VO 2+ The solvent includes at least one of the following: at least one trifluoromethanesulfonate, nitrate, sulfate, and chloride salt corresponding to at least one cation in the active material; the solvent includes water. Based on the principle of high-valence charge compensation, the high-valence cations of the cationic additives within the scope of this application have higher cation potential (CIP, charge / radius ratio), which can provide stronger electrostatic interactions and help enhance the bonding strength with anionic groups in the positive electrode active material, thereby stabilizing the crystal framework of the positive electrode active material. By adding the cationic additives within the scope of this application to the electrolyte, they fill the vacancies of transition metal ions in the positive electrode active material during the discharge process of the potassium-ion battery. Through the high-valence cation in-situ filling mechanism, the in-situ repair of the crystal structure of the positive electrode active material is achieved. The metal cations in the cationic additives form stable coordination bonds with the anions in the structure of the positive electrode active material, and the cationic additives can form an interface phase rich in inorganic matter on the surface of the positive electrode, thereby inhibiting the continuous dissolution of transition metal ions in the positive electrode active material and improving the cycle performance of the potassium-ion battery.

[0027] In some embodiments of this application, the concentration of the cationic additive in the electrolyte is 0.1 mol / L to 2 mol / L; preferably, the concentration of the cationic additive is 0.2 mol / L to 1 mol / L; more preferably, the concentration of the cationic additive is 0.2 mol / L to 0.5 mol / L. For example, the concentration of the cationic additive can be 0.1 mol / L, 0.15 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, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, or a range consisting of any two of these values. By adjusting the concentration of cationic additives in the electrolyte within the scope of this application, it is beneficial to further promote the in-situ repair of the crystal structure of the positive electrode active material by the cationic additives, further inhibit the continuous dissolution of transition metal ions in the positive electrode active material, and improve the cycle performance of potassium-ion batteries.

[0028] In some embodiments of this application, the cationic additive includes at least one of Al(CF3SO3)3, Fe(CF3SO3)3, Ce(CF3SO3)3, In(CF3SO3)3, Al(NO3)3, Fe(NO3)3, Ce(NO3)3, Cr(NO3)3, In(NO3)3, Zr(NO3)4, Al2(SO4)3, Fe2(SO4)3, Ce2(SO4)3, Cr2(SO4)3, In2(SO4)3, Zr(SO4)2, VOSO4, AlCl3, FeCl3, CeCl3, CrCl3, InCl3, and ZrCl4. The electrolyte including cationic additives within the above range is beneficial for further suppressing the continuous dissolution of transition metal ions from the positive electrode active material and improving the cycle performance of potassium-ion batteries.

[0029] In some embodiments of this application, the concentration of the potassium salt in the electrolyte is 10 mol / L to 30 mol / L. For example, the potassium salt concentration can be 10 mol / L, 12 mol / L, 14 mol / L, 16 mol / L, 18 mol / L, 20 mol / L, 22 mol / L, 24 mol / L, 26 mol / L, 28 mol / L, 30 mol / L, or a range of any two of these values. By controlling the concentration of the potassium salt in the electrolyte within the above range, it is beneficial to reduce the content of free water in the electrolyte, broaden the electrochemical stability window of the electrolyte, reduce the occurrence of side reactions, and thus further improve the cycle performance of the potassium-ion battery.

[0030] In some embodiments of this application, the potassium salt includes at least one of potassium trifluoromethanesulfonate (KCF3SO3), potassium difluorosulfonamide (KFSI), potassium acetate (CH3COOK), and potassium trifluoroacetate (CF3COOK). The electrolyte of this application includes potassium salts within the above-mentioned range, which have high solubility in water, facilitating the preparation of high-concentration potassium salt electrolytes. They are also less prone to crystallization and significantly broaden the electrochemical stability window of the electrolyte. Furthermore, the potassium salts within the above-mentioned range, in synergy with the cationic additives provided in this application, can form a stable interfacial film on the electrode surface, further suppressing side reactions and reducing the dissolution of transition metals in the positive electrode active material, thereby further improving the cycle performance of the potassium-ion battery.

[0031] In some embodiments of this application, the potassium salt includes potassium trifluoromethanesulfonate, and the concentration of potassium trifluoromethanesulfonate is 20 mol / L to 22 mol / L. This allows for the construction of a structurally stable water-in-salt electrolyte. The concentration of potassium trifluoromethanesulfonate within this range effectively binds free water molecules, significantly suppressing hydrogen evolution and oxygen evolution side reactions, effectively broadening the electrochemical stability window of the electrolyte, and achieving a good balance between ionic conductivity and viscosity, resulting in excellent ion transport kinetics for the electrolyte. Simultaneously, the synergistic effect of potassium trifluoromethanesulfonate and the cationic additive provided in this application facilitates the in-situ formation of a uniform and dense interfacial passivation film on the electrode surface, further suppressing electrode material dissolution and electrolyte side reactions, thereby further improving the battery's cycle performance and overall electrochemical performance.

[0032] In some embodiments of this application, the potassium salt includes potassium bis(fluorosulfonyl)imide, and the concentration of potassium bis(fluorosulfonyl)imide is 25 mol / L to 30 mol / L. This results in a stable water-in-salt electrolyte with a wide electrochemical window, excellent interfacial film-forming properties, high cycle stability, and good low-temperature performance. The synergistic effect of the cationic additives in this application further improves the battery's cycle performance and overall electrochemical performance.

[0033] In some embodiments of this application, the potassium salt includes potassium acetate, with a concentration of 25 mol / L to 28 mol / L. This forms a stable water-in-salt electrolyte, effectively reducing free water molecules, suppressing hydrogen and oxygen evolution side reactions, and broadening the electrochemical stability window. Furthermore, the electrolyte viscosity at the above concentration is moderate, exhibiting excellent ion transport kinetics, which is beneficial for achieving good rate performance. Simultaneously, the synergistic effect of potassium acetate and the cationic additive provided in this application can form a stable passivation layer at the electrode interface, further inhibiting electrode material dissolution and improving battery cycle stability. In addition, potassium acetate has the significant advantages of readily available raw materials, low cost, and environmentally friendly fluorine-free properties, making it suitable for large-scale energy storage applications.

[0034] In some embodiments of this application, the potassium salt comprises potassium trifluoroacetate, with a concentration of 10 mol / L to 15 mol / L. This allows for efficient solvation control at moderate concentrations, effectively reducing free water content and suppressing hydrogen and oxygen evolution side reactions, thus broadening the electrochemical stability window. The strong electron-withdrawing effect of trifluoromethyl groups imparts higher oxidative stability to the anion, reducing electrolyte decomposition and improving the system's voltage withstand capability. This concentration range achieves both low viscosity and good ionic conductivity without requiring excessively high concentrations, resulting in superior ion transport kinetics. Simultaneously, the synergistic effect of potassium trifluoroacetate and the cationic additives provided in this application forms a uniform and stable interfacial film on the electrode surface, inhibiting electrode material dissolution and further enhancing cycle stability.

[0035] In some embodiments of this application, the solvent further includes an organic solvent, which includes at least one of carbonate solvents, phosphate solvents, alcohol solvents, amide solvents, and sulfone solvents. Preferably, the carbonate solvent includes at least one of ethylene carbonate and propylene carbonate; the phosphate solvent includes at least one of trimethyl phosphate and triethyl phosphate; the alcohol solvent includes at least one of ethylene glycol and glycerol; the amide solvent includes at least one of formamide, N-methylformamide, and N,N-dimethylformamide; and the sulfone solvent includes at least one of dimethyl sulfoxide, sulfolane, and sulfolane. The inclusion of organic solvents within the above range in the electrolyte is beneficial for broadening the electrochemical stability window of the electrolyte. Simultaneously, it facilitates synergistic effects with potassium salts and cationic additives in the electrolyte, forming a stable interfacial film at the electrode interface, thereby inhibiting the continuous dissolution of transition metal ions in the positive electrode active material and improving the cycle performance of the potassium-ion battery.

[0036] In some embodiments of this application, the solvent further includes an organic solvent, wherein the volume ratio of the organic solvent to the water is from 0:1 to 10:1. For example, the volume ratio of the organic solvent to water in the solvent can be 0:1, 1:10, 1:8, 1:6, 1:4, 1:2, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1, or a range of any two of these values. This is beneficial for further improving the cycle performance of potassium-ion batteries.

[0037] The second aspect of this application provides a method for preparing the electrolyte provided in the first aspect of this application, comprising: stirring and dissolving the potassium salt, the cationic additive, and the solvent at a temperature of 30°C to 70°C to obtain a first solution; cooling the first solution to room temperature and bubbling it with an inert gas to obtain the electrolyte. For example, the stirring and dissolving temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or a range of any two of these values. The method for preparing the electrolyte provided in this application is simple, the reaction conditions are mild, and the cost is low, making it suitable for large-scale industrial application. The electrolyte prepared in this application helps to suppress the continuous dissolution of transition metal ions in the positive electrode active material and improves the cycle performance of potassium-ion batteries.

[0038] In some embodiments of this application, the stirring and dissolving time is 0.5h to 2h. For example, the stirring and dissolving time can be 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h, or a range of any two of these values. This is beneficial for obtaining a uniformly mixed electrolyte.

[0039] In some embodiments of this application, the inert gas includes argon or nitrogen.

[0040] In some embodiments of the present application, the time of the bubbling treatment is 0.5 h to 1 h. For example, the time of the bubbling treatment can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h or a range composed of any two of these values.

[0041] In some embodiments of the present application, the gas flow rate of the bubbling treatment is 2 mL / min to 10 mL / min. For example, the gas flow rate of the bubbling treatment can be 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, 6 mL / min, 7 mL / min, 8 mL / min, 9 mL / min, 10 mL / min or a range composed of any two of these values.

[0042] By bubbling an inert gas into the first solution, it is beneficial to remove the dissolved oxygen in the electrolyte and reduce the occurrence of side reactions.

[0043] The third aspect of the present application provides a potassium ion battery, which includes the electrolyte provided in the first aspect of the present application or the electrolyte prepared by the method provided in the second aspect of the present application. Since the potassium ion battery of the present application includes the above electrolyte, the potassium ion battery of the present application has all the advantages of the above electrolyte and will not be elaborated herein.

[0044] In some embodiments of the present application, the potassium ion battery includes a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a Prussian blue analogue. The chemical formula of the Prussian blue analogue is K 2-x M[Fe(CN)6] 1-y ·zH2O, where M includes at least one of Mn, Fe, Cu, Ni, Co, Zn, 0 < x < 1, 0 < y < 1, 0 < z < 1; the negative electrode plate includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. The negative electrode film layer includes a negative electrode active material, and the negative electrode active material includes at least one of an organic material and a polyanionic compound. Preferably, the organic material includes at least one of 3,4,9,10-perylene tetracarboxylic diimide (PTCDI) and 1,4,5,8-naphthalene tetracarboxylic dianhydride (PNTCDA), and the polyanionic compound includes potassium titanium phosphate (KTi2(PO4)3); more preferably, the negative electrode active material includes 3,4,9,10-perylene tetracarboxylic diimide (PTCDI).

[0045] The positive electrode active material of the present application includes a Prussian blue analogue K 2-x M[Fe(CN)6] 1-yZH₂O, with its three-dimensional network framework structure and large interstitial sites facilitating rapid potassium ion insertion / extraction, is an excellent positive electrode active material for potassium-ion batteries. However, Prussian blue analogues are prone to continuous dissolution of transition metal ions in aqueous electrolytes, leading to structural collapse of the positive electrode active material and affecting the cycle performance of potassium-ion batteries. This application incorporates a cationic additive into the electrolyte, which can fill the vacancies caused by the dissolution of transition metal ions in Prussian blue analogues during potassium-ion battery discharge. The metal cations in the cationic additive form stable coordination bonds with the cyano groups in the Prussian blue analogues, thereby stabilizing the crystal framework of the positive electrode active material. Furthermore, the cationic additive can form an inorganic-rich interfacial phase on the surface of the positive electrode, thus inhibiting the continuous dissolution of transition metal ions from the Prussian blue analogues and improving the cycle performance of potassium-ion batteries. In addition, the negative electrode active material provided in this application exhibits good compatibility with the electrolyte, reducing side reactions. Therefore, the matching of the electrolyte, positive electrode active material, and negative electrode active material provided in this application is beneficial to improving the cycle performance of potassium-ion batteries and resulting in excellent overall electrochemical performance.

[0046] The positive and negative electrode active materials used in this application are commercially available or can be prepared in-house. This application does not impose any particular restrictions on the preparation methods of the positive or negative electrode active materials, as long as the purpose of this application is achieved. For example, the positive electrode active material is a Prussian blue analogue K. 2-x M[Fe(CN)6] 1-y •zH₂O can be prepared by co-precipitation: First, prepare an aqueous solution of potassium ferrocyanide to obtain solution A; then prepare a salt solution containing element M to obtain solution B. Mix solutions A and B, then allow to stand for aging, centrifuge, and dry to obtain the Prussian blue analogue K. 2-x M[Fe(CN)6] 1-y ·zH2O.

[0047] In some embodiments of this application, the positive electrode current collector includes at least one selected from titanium mesh, carbon cloth, carbon felt, and graphite paper; the negative electrode current collector includes at least one selected from carbon-coated aluminum foil, carbon felt, graphite paper, and carbon-coated copper foil. Preferably, the positive electrode current collector includes titanium mesh, and the negative electrode current collector includes carbon-coated aluminum foil. The positive electrode current collector provided in this application has high chemical inertness and is not easily oxidized or corroded at the high positive electrode potential of potassium-ion batteries. Furthermore, it is not prone to side reactions with the electrolyte of this application, exhibiting stable electrochemical performance, thereby contributing to improved cycle life and safety of potassium-ion batteries. The negative electrode current collector provided in this application, while meeting electrochemical stability requirements, has low manufacturing costs and is suitable for industrial applications.

[0048] In this application, the positive electrode includes a positive electrode film layer located on at least one side of the positive electrode current collector. The phrase "positive electrode film layer located on at least one side of the positive electrode current collector" means that the positive electrode film layer can be disposed on one surface of the positive electrode current collector along its thickness direction, or on two surfaces of the positive electrode current collector along its thickness direction. It should be noted that "surface" here can be the entire surface area of ​​the positive electrode current collector, or only a portion thereof; this application has no particular limitation, as long as the purpose of this application is achieved. This application has no particular limitation on the thickness of the positive electrode film layer and the positive electrode current collector, as long as the purpose of this application is achieved. For example, the thickness of the single-sided positive electrode material layer is 10 μm to 500 μm, and the thickness of the positive electrode current collector is 10 μm to 200 μm.

[0049] In this application, the positive electrode film layer also includes a positive electrode conductive agent and a positive electrode binder. This application does not impose any particular limitation on the types of positive electrode conductive agents and positive electrode binders, as long as they achieve the purpose of this application. For example, the positive electrode conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), acetylene black, Ketjen black, carbon nanotubes, graphene, or carbon fiber. For example, the positive electrode binder may include, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, or fluorinated acrylate resin. This application does not impose any particular limitation on the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode film layer; those skilled in the art can select them according to actual needs, as long as the purpose of this application is achieved.

[0050] In this application, there are no particular limitations on the preparation method of the positive electrode sheet, as long as it achieves the purpose of this application. For example, it can be prepared by the following method: mixing positive electrode active material, positive electrode conductive agent, and positive electrode binder, and adding N-methylpyrrolidone (NMP) and stirring evenly. The positive electrode slurry is uniformly coated on the surface of the positive electrode current collector, and after drying, a positive electrode sheet coated with a positive electrode film layer is obtained. Then, it is cold-pressed and cut to obtain the positive electrode sheet.

[0051] In this application, the negative electrode sheet includes a negative current collector and a negative electrode film layer located on at least one side of the negative current collector. The phrase "the negative electrode film layer is located on at least one side of the negative current collector" means that the negative electrode film layer can be disposed on one surface of the negative current collector along its thickness direction, or on two surfaces of the negative current collector along its thickness direction. It should be noted that the "surface" here can be the entire surface area of ​​the negative current collector, or only a portion thereof; this application has no particular limitation, as long as the purpose of this application is achieved. This application has no particular limitation on the thickness of the negative electrode film layer and the negative current collector, as long as the purpose of this application is achieved. For example, the thickness of the single-sided negative electrode material layer is 10 μm to 500 μm, and the thickness of the negative current collector is 10 μm to 200 μm.

[0052] The negative electrode material layer also includes a negative electrode conductive agent and a negative electrode binder. This application does not impose any particular limitation on the types of negative electrode conductive agents and binders, as long as they achieve the purpose of this application. For example, the negative electrode conductive agent may include, but is not limited to, at least one of conductive carbon black (Super P), acetylene black, Ketjen black, carbon nanotubes, graphene, or carbon fibers. The aforementioned carbon nanotubes may include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The aforementioned carbon fibers may include, but are not limited to, vapor-grown carbon fibers (VGCF) and / or carbon nanofibers. For example, the negative electrode binder may include, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), or carboxymethyl chitosan (CMCS). This application does not impose any particular limitation on the mass ratio of the negative electrode active material, conductive agent, and binder in the negative electrode film layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application is achieved. In some embodiments of this application, the negative electrode film layer may further include a thickener. This application does not particularly limit the type of thickener, as long as it achieves the purpose of this application. For example, the thickener may include, but is not limited to, at least one of sodium carboxymethyl cellulose or lithium carboxymethyl cellulose. This application does not particularly limit the mass ratio of the negative electrode active material, conductive agent, binder, and thickener in the negative electrode film layer. Those skilled in the art can select according to actual needs, as long as the purpose of this application is achieved.

[0053] In this application, there are no particular restrictions on the preparation method of the negative electrode sheet, as long as it achieves the purpose of this application. For example, it can be prepared by the following method: adding negative electrode active material, negative electrode conductive agent, and negative electrode binder to deionized water and stirring evenly to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on the surface of the negative electrode current collector, and after drying, a negative electrode sheet coated with a negative electrode film layer is obtained. Then, it is cold-pressed and cut to obtain the negative electrode sheet.

[0054] In this application, the potassium-ion battery also includes a separator. There are no particular limitations on the separator, as long as it achieves the purpose of this application. For example, the separator material may include, but is not limited to, at least one of polyethylene (PE), polypropylene (PP), and glass fiber. The separator type may include at least one of woven membrane, nonwoven fabric, microporous membrane, composite membrane, rolled membrane, or spun membrane. In this application, there are no particular limitations on the separator thickness, as long as it achieves the purpose of this application; for example, the separator thickness may be from 10 μm to 1000 μm.

[0055] In this application, the potassium-ion battery also includes a casing for housing the positive electrode, separator, negative electrode, and electrolyte, as well as other components known in the field of potassium-ion batteries. This application does not limit the scope of these other components. This application does not impose any particular limitation on the casing; it can be a casing known in the art, as long as it achieves the purpose of this application. For example, the casing can be a rigid casing or a flexible casing. The material of the rigid casing can be metal; this application does not limit the type of metal and can use known metal rigid casings, as long as they achieve the purpose of this application. The flexible casing can be a metal plastic film, such as aluminum-plastic film, steel-plastic film, etc. Specifically, the potassium-ion battery described in this application can be a button cell, a pouch cell, or a cylindrical cell; this application does not impose any particular limitation, as long as it achieves the purpose of this application.

[0056] The preparation process of the potassium-ion battery described in this application is well known to those skilled in the art, and this application does not impose any particular limitations. For example, the preparation process of the potassium-ion battery may include, but is not limited to, the following steps: stacking the positive electrode, separator, and negative electrode in sequence, and performing operations such as winding and folding as needed to obtain a wound electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain a potassium-ion battery. Alternatively, stacking the positive electrode, separator, and negative electrode in sequence, and then fixing the four corners of the entire stacked structure with tape to obtain a stacked electrode assembly; placing the electrode assembly into a housing; injecting electrolyte into the housing and sealing it to obtain a potassium-ion battery. In addition, overcurrent protection elements, conductive plates, etc., may be placed in the housing as needed to prevent pressure rise and overcharging / discharging inside the potassium-ion battery.

[0057] The fourth aspect of this application provides an application of the potassium-ion battery provided in the third aspect of this application in an energy storage system.

[0058] Example The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0059] Example 1 <Preparation of Electrolyte> Weigh 21 mmol of potassium trifluorosulfonate (KOTF) and 0.2 mmol of aluminum trifluorosulfonate (Al(OTF)3) and place them in an electrolyte preparation bottle. Add 1 ml of chromatographic grade H2O and incubate at 60°C with shaking for 1 hour until a clear, transparent, colorless first solution is formed. Cool the first solution to room temperature (25°C) and purge it with high-purity argon gas at a rate of 6 mL / min for 1 hour to remove dissolved oxygen, thus obtaining the electrolyte. In this example, the electrolyte has a KOTF concentration of 21 mol / L and an Al(OTF)3 concentration of 0.2 mol / L.

[0060] <Preparation of Positive Electrode Active Materials> 12 mmol of K₄Fe(CN)₆·3H₂O was added to 350 ml of deionized water and dissolved with stirring at 60 °C to form solution A. 12 mmol of MnSO₄·H₂O and 100 mmol of CH₃COOK were dissolved in 350 ml of deionized water to form solution B. Solution B was added dropwise to solution A at a rate of 10 ml / min, with continuous stirring at 60 °C for 12 hours. After the reaction was complete, the mixture was allowed to stand at 60 °C for 12 hours to age. The white precipitate was collected by centrifugation and washed twice each with deionized water and ethanol. The washed precipitate was then vacuum-dried at 70 °C for 12 hours to obtain the KMnPBA positive electrode active material, with the chemical formula K₄Fe(CN)₆·3H₂O. 1.88 Mn[Fe(CN)6] 0.97 0.51H2O.

[0061] <Preparation of the positive electrode> The above-prepared positive electrode active material KMnPBA, conductive carbon black Super P, and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 7:2:1. N-methylpyrrolidone (NMP) was added as a solvent, and the mixture was thoroughly mixed to form a uniform positive electrode slurry with a solid content of 70%. The positive electrode slurry was uniformly coated onto a titanium mesh with a thickness of 300 μm, dried at 60°C for 6 hours, and then vacuum dried at 110°C for 12 hours. The resulting electrode sheet was rolled and then punched to obtain a positive electrode sheet with a diameter of 12 mm and a positive electrode film thickness of 30 μm (positive electrode active material loading of 1.6 mg / cm).2 ).

[0062] Assembly of the three-electrode system Using the positive electrode sheet prepared above as the working electrode, activated carbon as the counter electrode, Ag / AgCl as the reference electrode, and the electrolyte prepared above as the electrolyte, a three-electrode system is assembled.

[0063] <Preparation of Negative Electrode Sheets> PTCDI (anode active material), conductive carbon black (conductive agent), and PVDF (binder) were mixed in a 7:2:1 mass ratio, with NMP added as a solvent. The mixture was thoroughly mixed to form a uniform anode slurry with a solid content of 60%. The anode slurry was then uniformly coated onto a 16 μm thick carbon-coated aluminum foil and vacuum-dried at 110°C for 12 hours. The resulting electrode sheet was then rolled and punched to obtain a 14 mm diameter anode sheet with a 25 μm anode film thickness (anode active material loading of 1.4 mg / cm³). 2 ).

[0064] Assembly of Potassium-ion Batteries In an argon-filled glove box, the above-prepared positive electrode, separator (separator type: Whatman (GF / D), thickness: 500 μm), the above-prepared negative electrode, and electrolyte are assembled into a CR2032 coin cell, wherein the amount of electrolyte added is 100 μl.

[0065] Examples 2 to 8 Except for the section on <Preparation of Electrolyte>, where the type of cationic additive was adjusted according to Table 1, the rest is the same as in Example 1.

[0066] Examples 9 to 15 Except for the section on <Preparation of Electrolyte>, where the concentration of the cationic additive was adjusted according to Table 1, the rest of the steps were the same as in Example 1.

[0067] Examples 16 to 18 Except for the section on <Preparation of Electrolyte>, where the type and concentration of potassium salt were adjusted according to Table 1, the rest of the instructions are the same as in Example 1.

[0068] Examples 19 to 22 Except for <Preparation of Electrolyte>, where the solvent was adjusted to a mixture of water and organic solvent according to Table 1, the rest is the same as in Example 1.

[0069] Comparative Example 1 Except for the absence of cationic additive Al(CF3SO3)3 in the <Preparation of Electrolyte>, the rest is the same as in Example 1.

[0070] Comparative Example 2 Except for the absence of cationic additive Al(CF3SO3)3 in the <Preparation of Electrolyte>, the rest is the same as in Example 20.

[0071] Comparative Examples 3 to 4 Except for <Preparation of Electrolyte>, where the cationic additives are replaced with Ca(CF3SO3)2 and Mg(CF3SO3)2 according to Table 1, the rest is the same as in Example 1.

[0072] ICP-OES analysis of the dissolution behavior of the transition metal element Mn in Example 1 and Comparative Example 1 The three-electrode systems assembled in Example 1 and Comparative Example 1 were subjected to constant current charge-discharge tests using Xinwei Battery Testing Equipment. The voltage window was 0-1.25 V (vs. Ag / AgCl): at 25°C, the three-electrode system was charged at a constant current of 0.2 A / g to a voltage of 1.25 V, and then discharged at a constant current of 0.2 A / g to a voltage of 0 V. This constituted one charge-discharge cycle, and the above charge-discharge cycle was repeated up to 20 times.

[0073] Electrolytes from the initial electrolyte, after the first charge, after the first discharge, after the 4th discharge, after the 8th discharge, after the 10th discharge, and after the 20th discharge were subjected to ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) testing. Specifically, for each test, 1 mL of electrolyte was added to a volumetric flask, and the volume was adjusted to 50 mL with ultrapure water and mixed thoroughly (dilution treatment). Then, 2 mL of the mixed liquid was used for ICP-OES testing.

[0074] The test results of aluminum ion content and manganese ion content of the initial state electrolyte, the electrolyte after the first charge, and the electrolyte after the first discharge in Example 1 after dilution treatment are shown in Table 1 and... Figure 1 As shown.

[0075] Table 1

[0076] From Table 1 and Figure 1 As can be seen, when the electrolyte is first charged to 1.25V, the concentration of manganese ions increases significantly, indicating that manganese dissolution mainly occurs during the charging process. When the electrolyte is discharged to 0V, the concentration of aluminum ions decreases significantly, which corresponds to the in-situ substitution reaction of aluminum ions entering the crystal framework during the discharge process. This also directly verifies the in-situ filling mechanism of aluminum ions filling manganese vacancies during the discharge process.

[0077] The test results of aluminum and manganese ion content after dilution of the initial state electrolyte, electrolyte after the first discharge, electrolyte after the fourth discharge, electrolyte after the eighth discharge, electrolyte after the tenth discharge, and electrolyte after the twentieth discharge in Example 1 are shown in Table 2. Figure 2 As shown.

[0078] Table 2

[0079] The test results of manganese ion content after dilution of the electrolyte in the initial state, electrolyte after the first discharge, electrolyte after the fourth discharge, electrolyte after the eighth discharge, electrolyte after the tenth discharge, and electrolyte after the twentieth discharge of Comparative Example 1 are shown in Table 3. Figure 3 As shown.

[0080] Table 3

[0081] From Table 2 and Figure 2 It can be seen that in the first 10 cycles of the three-electrode system in Example 1, the aluminum ion content in the electrolyte gradually decreased (from 56.535 ppm to 44.439 ppm), while the manganese ion content gradually increased (from 0 ppm to 12.893 ppm). After 10 cycles, both the manganese ion and aluminum ion contents tended to stabilize, confirming that aluminum ion substitution mainly occurred in the first 10 cycles, and that manganese ion dissolution was effectively suppressed. In comparison, from Table 3 and... Figure 3 As can be seen, the manganese ion content in the electrolyte of Comparative Example 1 continuously increases, reaching 16.895 ppm after 10 cycles and 21.922 ppm after 20 cycles. This demonstrates that by adding a cationic additive to the electrolyte of this application, during the discharge process of a potassium-ion battery, the high-valence cations in the cationic additive fill the vacancies for the dissolution of transition metal ions in the positive electrode active material in situ, inhibiting the continuous dissolution of transition metal ions in the positive electrode active material.

[0082] Raman spectroscopy test The three-electrode system assembled in Example 1 was subjected to constant current charge-discharge testing using Xinwei Battery Testing Equipment. The voltage window was 0-1.25 V (vs. Ag / AgCl): at 25°C, the three-electrode system was charged at a constant current of 0.2 A / g to a voltage of 1.25 V, and then discharged at a constant current of 0.2 A / g to a voltage of 0 V. This constituted one charge-discharge cycle, and the above charge-discharge cycle was repeated up to 20 times.

[0083] After 20 cycles, the electrode sheet was removed, washed with dimethyl carbonate (DMC), and vacuum dried. Confocal Raman microscopy (HORIBA LabRAM HR Evolution) was used to test both the uncycled initial KMnPBA cathode prepared in Example 1 and the KMnPBA cathode prepared after 20 cycles. All tests were conducted at room temperature and atmospheric conditions, with an excitation wavelength of 532 nm.

[0084] from Figure 4 As can be seen from the data, compared with the initial KMnPBA cathode, the Raman spectrum of the cathode after 20 cycles shows that at 2078 cm⁻¹... -1 A new acromion appears, belonging to Al. 3+ -N≡C-Fe 2+ Vibration modes, indicating Al 3+ Successfully entered the crystal lattice to form coordination bonds.

[0085] Cyclic performance test The potassium-ion batteries assembled in the aforementioned embodiments and comparative examples were subjected to constant current charge-discharge tests using Xinwei Battery Testing Equipment. The test results are shown in Table 1.

[0086] (1) 0.2 A / g Cyclic Performance Test: At 25℃, the potassium-ion battery was charged at a constant current of 0.2 A / g to a voltage of 2.2V, and then discharged at a constant current of 0.2 A / g to a voltage of 0V. The initial discharge capacity was recorded as Q1, which constituted one charge-discharge cycle. This charge-discharge cycle was repeated for 500 cycles, and the final discharge capacity was recorded as Q2. Capacity retention rate after 500 cycles of 0.2 A / g = Q2 / Q1 × 100% (2) 6 A / g Cycling Performance Test: At 25℃, the potassium-ion battery was charged at a constant current of 6 A / g to a voltage of 2.2V, and then discharged at a constant current of 6 A / g to a voltage of 0V. The initial discharge capacity was recorded as P1. This constituted one charge-discharge cycle. The above charge-discharge cycle was repeated for 30,000 cycles, and the final discharge capacity was recorded as P2. Capacity retention rate after 30,000 cycles of 6 A / g = P2 / P1 × 100% The cycle performance of potassium-ion batteries is evaluated by capacity retention rate; the higher the capacity retention rate, the better the cycle performance of the potassium-ion battery.

[0087] The preparation and performance parameters of each embodiment and comparative example are shown in Table 4.

[0088] Table 4

[0089] Note: " / " in Table 4 indicates that no relevant preparation parameters are available.

[0090] As can be seen from Examples 1 to 22 and Comparative Examples 1 to 4, the electrolytes in the embodiments of this application include cationic additives within the scope of this application, which enables the potassium-ion battery to have a higher capacity retention rate after 500 cycles at 0.2 A / g and a capacity retention rate after 30,000 cycles at 6 A / g, indicating that the potassium-ion battery of the embodiments of this application has better cycle performance. However, Comparative Examples 1 and 2 did not add cationic additives, and the cationic additives added to Comparative Examples 3 and 4 were not within the scope of this application. The capacity retention rates after 500 cycles at 0.2 A / g and after 30,000 cycles at 6 A / g of Comparative Examples 1 to 4 were both lower, indicating that the potassium-ion battery of the comparative examples had poor cycle performance.

[0091] As can be seen from Examples 1, 9 to 15, the concentration of the cationic additive in the electrolyte affects the cycle performance of the potassium-ion battery. By adjusting the concentration of the cationic additive within the range of 0.1 mol / L to 2 mol / L, the obtained potassium-ion battery has better cycle performance.

[0092] As can be seen from Examples 1, 16 to 18, the type and concentration of potassium salt in the electrolyte affect the cycle performance of potassium-ion batteries. By selecting potassium salts within the scope of this application and adjusting the concentration of potassium salts within the scope of this application, the obtained potassium-ion batteries have better cycle performance.

[0093] As can be seen from Examples 19 to 22 and Comparative Example 2, when the solvent is a mixture of water and an organic solvent, and the electrolyte includes cationic additives within the scope of this application, the resulting potassium-ion battery exhibits superior cycle performance. Furthermore, as can be seen from Examples 1 and 19 to 22, when the electrolyte solvent of this application is pure water, the resulting potassium-ion battery exhibits superior cycle performance.

[0094] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0095] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An electrolyte, characterized by, The electrolyte comprises a potassium salt, a cation additive and a solvent; the cation additive comprises at least one of the following: Al 3+ , Fe 3+ , Ce 3+ , Cr 3+ , In 3+ , Zr 4+ , VO 2+ corresponding to at least one of triflate, nitrate, sulfate, chloride The solvent includes water.

2. The electrolyte according to claim 1, characterized in that, In the electrolyte, the concentration of the cationic additive is 0.1 mol / L to 2 mol / L; preferably, the concentration of the cationic additive is 0.2 mol / L to 1 mol / L; more preferably, the concentration of the cationic additive is 0.2 mol / L to 0.5 mol / L.

3. The electrolyte according to claim 1, characterized in that, The cationic additive includes at least one of Al(CF3SO3)3, Fe(CF3SO3)3, Ce(CF3SO3)3, In(CF3SO3)3, Al(NO3)3, Fe(NO3)3, Ce(NO3)3, Cr(NO3)3, In(NO3)3, Zr(NO3)4, Al2(SO4)3, Fe2(SO4)3, Ce2(SO4)3, Cr2(SO4)3, In2(SO4)3, Zr(SO4)2, VOSO4, AlCl3, FeCl3, CeCl3, CrCl3, InCl3, and ZrCl4.

4. The electrolyte according to claim 1, characterized in that, In the electrolyte, the concentration of the potassium salt is 10 mol / L to 30 mol / L.

5. The electrolyte according to claim 1, characterized in that, The potassium salt includes at least one of potassium trifluoromethanesulfonate, potassium difluorosulfonamide, potassium acetate, and potassium trifluoroacetate.

6. The electrolyte according to any one of claims 1 to 5, characterized in that, The solvent further includes an organic solvent, which satisfies at least one of the following conditions: (1) The organic solvent includes at least one of carbonate solvents, phosphate solvents, alcohol solvents, amide solvents, and sulfone solvents; (2) In the solvent, the volume ratio of the organic solvent to the water is 0:1 to 10:

1.

7. A method for preparing the electrolyte according to any one of claims 1 to 6, characterized in that, include: The potassium salt, the cationic additive, and the solvent are stirred and dissolved at 30°C to 70°C to obtain a first solution; The first solution was cooled to room temperature and then bubbled with an inert gas to obtain the electrolyte.

8. The method according to claim 7, characterized in that, At least one of the following conditions must be met: (1) The stirring and dissolving time is 0.5 h to 2 h; (2) The inert gas includes argon or nitrogen; (3) The bubbling treatment time is 0.5 h to 1 h; (4) The ventilation rate of the bubbling treatment is 2 mL / min to 10 mL / min.

9. A potassium-ion battery, characterized in that, The electrolyte includes any one of claims 1 to 6 or an electrolyte prepared by the method described in any one of claims 7 to 8.

10. The potassium-ion battery according to claim 9, characterized in that, The potassium ion battery comprises a positive electrode sheet and a negative electrode sheet, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises a Prussian blue analogue, the Prussian blue analogue has a chemical formula of K 2-x M[Fe(CN)6] 1-y ·zH2O, wherein M comprises at least one of Mn, Fe, Cu, Ni, Co and Zn, 0 The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer located on at least one side of the negative electrode current collector, the negative electrode film layer comprises a negative electrode active material, the negative electrode active material comprises at least one of an organic material and a polyanionic compound.

11. The potassium-ion battery according to claim 10, characterized in that, The organic material includes at least one of 3,4,9,10-perylenetetracarboxylic diimide and 1,4,5,8-naphthalenetetracarboxylic anhydride, and the polyanionic compound includes potassium titanium phosphate.

12. The potassium-ion battery according to claim 10, characterized in that, The positive electrode current collector includes at least one of titanium mesh, carbon cloth, carbon felt, and graphite paper; the negative electrode current collector includes at least one of carbon-coated aluminum foil, carbon felt, graphite paper, and carbon-coated copper foil.

13. The application of the potassium-ion battery according to any one of claims 9-12 in an energy storage system.

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