Preparation method and application of cathode material

Abstract

The invention provides a preparation method and application of a cathode material, and the preparation method of the cathode material comprises the following steps: weighing raw materials of a vanadium source, a phosphorus source, a potassium source and a rare earth element source, then adding water for dissolving, drying, calcining and ball-milling to obtain a rare earth element doped cathode material. The cathode material is high in energy density, stable in structure and good in conductivity, and the cycle performance of the battery can be improved. Particularly, a K < + > diffusion channel of the cathode material is obviously enlarged, and the cathode material has relatively high rate capability and has profound significance in application of the cathode material of the potassium storage secondary battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a method for preparing a cathode material and its application. Background Technology

[0002] In recent years, the rapid development of lithium-ion batteries has led to the massive depletion of lithium resources, resulting in a gradual increase in the cost of lithium-ion batteries and limiting their large-scale application. Potassium, an alkali metal element, belongs to the same group as lithium and is not only abundant in the Earth's crust but also possesses a similar energy storage mechanism to lithium-ion batteries. However, due to the large ionic radius of potassium ions, their diffusion in the bulk phase is slow, resulting in low electronic conductivity and poor rate performance. Therefore, finding suitable potassium storage materials is crucial for the development of potassium-ion batteries.

[0003] Currently, while some transition metal oxides, Prussian blue compounds, and polyanionic cathode materials have exhibited suitable potassium storage performance, their drawbacks are also quite significant. For example, layered oxide cathode materials, although theoretically having high specific capacity and Kc... + Two-dimensional diffusion within the layers is relatively fast, but layered oxides exhibit poor stability in air, and the interaction between interlayer oxygens is strong, particularly at K... + Phase transitions easily occur during insertion / extraction, severely affecting structural stability and leading to poor electrochemical cycling performance. While Prussian blue compounds exhibit high operating voltages, their unique structural defects attract a large number of water molecules for coordination, and these water molecules are difficult to remove, resulting in poor cycle life. In contrast, polyanionic materials, due to their stable framework structure, exhibit high K... + The volume change during insertion / extraction is small, especially for polyanionic materials represented by KVOPO4 and K3V2(PO4)3 phosphates. These materials not only have excellent ionic conductivity, but also exhibit higher structural stability and higher operating potential, making them a class of highly promising cathode materials for potassium-ion batteries.

[0004] Although conventional polyanionic materials have relatively stable structures, their low electronic conductivity and slow ion diffusion rate severely limit their further applications. Even if related technologies improve polyanionic materials through carbon coating technology, it is difficult to significantly improve their conductivity. Summary of the Invention

[0005] To address the problems and shortcomings of existing technologies, this invention provides a method for preparing a cathode material and its application. This cathode material exhibits high energy density, structural stability, and good conductivity, which is beneficial for improving the cycle performance of batteries. Specifically, the Kc of this cathode material... + The diffusion channels are significantly expanded, resulting in higher rate performance, which has profound significance for the application of cathode materials in potassium storage secondary batteries.

[0006] According to a first aspect of the present invention, a method for preparing a cathode material is provided, comprising the following steps: weighing raw materials vanadium source, phosphorus source, potassium source and rare earth element source, then dissolving them in water, drying, calcining and ball milling to obtain a rare earth element-doped cathode material.

[0007] Preferably, the molar ratio of potassium source, vanadium source, rare earth element source and phosphorus source is 1:(0.1-x):x:1, 0<x<0.1.

[0008] Preferably, the vanadium source includes at least one of vanadium dioxide, vanadium trioxide, vanadium pentoxide, and ammonium metavanadate; And / or, the phosphorus source includes at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate; And / or, the potassium source includes at least one of potassium dihydrogen phosphate, potassium carbonate, and potassium oxalate; And / or, rare earth element sources include at least one of the following: lutetium source, scandium source, yttrium source, lanthanum source, cerium source, praseodymium source, neodymium source, promethium source, samarium source, europium source, gadolinium source, terbium source, dysprosium source, holmium source, erbium source, thulium source, and ytterbium source.

[0009] Preferably, dissolving in water includes adding deionized water and stirring at 70-100°C for 2-6 hours; And / or, drying includes baking at 80~100℃ for 8~16 hours by means of forced air; And / or, calcination is carried out in a tube furnace, and the calcination temperature is raised to 800~1000℃ under inert gas protection, and the holding time is 12~18h; And / or, ball milling is carried out by adding water to the ball mill, with the mass ratio of balls, raw materials and deionized water being (4~6):1:1.

[0010] Preferably, the preparation steps include weighing raw materials vanadium source, phosphorus source, potassium source, rare earth element source and citric acid, then dissolving them in water, drying, calcining and ball milling to obtain a cathode material doped with rare earth elements and coated with carbon.

[0011] Preferably, the amount of citric acid added is such that the carbon content accounts for 8wt% to 15wt% of the cathode material mass.

[0012] According to a second aspect of the present invention, a cathode material prepared by any of the above-described preparation methods is provided.

[0013] According to a third aspect of the present invention, a cathode electrode is provided, comprising: the cathode material described above.

[0014] According to a fourth aspect of the present invention, a battery is provided, comprising: the cathode electrode described above.

[0015] Preferably, the battery is a potassium-ion battery.

[0016] In summary, the present invention has the following advantages over the prior art: The cathode material prepared in this invention incorporates rare earth elements. Rare earth elements are characterized by large radius and high charge, and their introduction as dopant elements into the cathode material can expand the K-axis of the cathode material. + The diffusion channels enable the cathode material to possess high energy density, stable crystal structure, and excellent conductivity, thereby improving the rate performance of the cathode material and enhancing the cycle stability of the battery. This has profound significance for the application of cathode materials in potassium storage secondary batteries. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] According to a first aspect of the present invention, a method for preparing a cathode material is provided, comprising the following steps: weighing raw materials vanadium source, phosphorus source, potassium source and rare earth element source, then dissolving them in water, drying, calcining and ball milling to obtain a rare earth element-doped cathode material.

[0019] The cathode material preparation method provided by this invention, through controlling the process steps of mixing, drying, calcination, and ball milling, can prepare a cathode material with excellent conductivity. Vanadium, phosphorus, potassium, and rare earth element sources are dissolved in water and mixed to ensure uniform dispersion of these sources. Subsequent drying and calcination processes promote the breaking and recombination of chemical bonds, resulting in a cathode material with excellent conductivity. 3+ Bulk doping with rare earth elements at specific sites introduces larger rare earth ions into the cathode material, which can expand the K-axis of the cathode material. + The diffusion channel enables the cathode material to have high energy density and excellent conductivity, thereby improving the intrinsic conductivity of the cathode material and improving its rate performance. It is an excellent potassium storage cathode material, which in turn improves the cycle stability of batteries using this cathode material, especially meeting the requirements of potassium-ion batteries for high energy density and long cycle life.

[0020] In one or more embodiments, the molar ratio of potassium source, vanadium source, rare earth element source, and phosphorus source is 1:(0.1-x):x:1, where 0 < x < 0.1. Exemplarily, x can be equal to 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. This invention achieves optimal rate performance of the cathode material by controlling the amount of rare earth element source added.

[0021] In one or more embodiments, the vanadium source includes at least one of vanadium dioxide, vanadium trioxide, vanadium pentoxide, and ammonium metavanadate.

[0022] In one or more embodiments, the phosphorus source includes at least one of ammonium phosphate, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate.

[0023] In one or more embodiments, the potassium source includes at least one of potassium dihydrogen phosphate, potassium carbonate, and potassium oxalate.

[0024] In one or more embodiments, the rare earth element source includes at least one of the following: lutetium source, scandium source, yttrium source, lanthanum source, cerium source, praseodymium source, neodymium source, promethium source, samarium source, europium source, gadolinium source, terbium source, dysprosium source, holmium source, erbium source, thulium source, and ytterbium source.

[0025] In one or more embodiments, dissolving with water includes adding deionized water and stirring at 70-100°C for 2-6 hours. Exemplarily, the temperature can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc., but is not limited to the listed temperature values; other unlisted values ​​within the temperature range are also applicable. The stirring time can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, etc., but is not limited to the listed stirring time values; other unlisted values ​​within the stirring time range are also applicable. This invention achieves uniform mixing of materials by controlling the stirring temperature and stirring time.

[0026] In one or more embodiments, drying includes baking at 80-100°C for 8-16 hours using a forced-air method. Exemplarily, the drying temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, etc., but is not limited to the listed temperature values; other unlisted values ​​within the temperature range are also applicable. The drying time can be 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h, 12 h, 12.5 h, 13 h, 13.5 h, 14 h, 14.5 h, 15 h, 15.5 h, 16 h, etc., but is not limited to the listed time values; other unlisted values ​​within the time range are also applicable. This invention ensures that the mixture is fully dried and structurally stable by controlling the drying time and temperature.

[0027] In one or more embodiments, calcination is carried out in a tubular furnace, with the calcination temperature raised to 800-1000°C under inert gas protection, and the holding time is 12-18 hours. Exemplarily, the calcination temperature can be 800°C, 850°C, 900°C, 950°C, 1000°C, etc., but is not limited to the listed temperature values; other unlisted values ​​within the temperature range are also applicable. The holding time can be 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours, 15 hours, 15.5 hours, 16 hours, 16.5 hours, 17 hours, 17.5 hours, 18 hours, etc., but is not limited to the listed time values; other unlisted values ​​within the time range are also applicable. This invention improves calcination efficiency and ensures the structural stability of the cathode material by controlling the calcination temperature and holding time.

[0028] In one or more embodiments, ball milling is performed by adding water, with the mass ratio of balls, raw materials, and deionized water being (4~6):1:1. Exemplarily, the mass ratio of balls, raw materials, and deionized water can be 4:1:1, 5:1:1, 6:1:1, etc. This invention obtains cathode materials of optimal size by controlling the ball ratio.

[0029] In addition to the above preparation steps, the preparation steps of the cathode material of the present invention may also include weighing raw materials vanadium source, phosphorus source, potassium source, rare earth element source and citric acid, then dissolving in water, drying, calcining and ball milling to obtain a cathode material doped with rare earth elements and coated with carbon.

[0030] The cathode material preparation method provided by this invention, through controlling the process steps of mixing, drying, calcination, and ball milling, can prepare a cathode material with excellent conductivity. Vanadium source, phosphorus source, potassium source, rare earth element source, and citric acid are dissolved in water and mixed. Utilizing the chelating effect of citric acid, the vanadium source, phosphorus source, potassium source, and rare earth element source can be uniformly dispersed to form a stable mixed system. The subsequent drying and calcination processes promote the breaking and recombination of chemical bonds, resulting in a cathode material with excellent conductivity. 3+ Bulk doping with rare earth elements at specific sites introduces larger rare earth ions into the cathode material, which can expand the K-axis of the cathode material. + The diffusion channels enable the cathode material to possess high energy density and excellent conductivity. Combined with the carbon coating structure of the cathode material, the intrinsic conductivity of the cathode material is further improved, greatly enhancing the rate performance of the cathode material. Moreover, the structural stability of the cathode material is significantly improved, effectively buffering the structural deformation of the cathode material frame during charge and discharge. This makes the cathode material an excellent potassium storage cathode material, improving the cycle stability of batteries using this cathode material, especially meeting the requirements of potassium-ion batteries for high energy density and long cycle life.

[0031] In one or more embodiments, the amount of citric acid added satisfies the requirement that the carbon content accounts for 8 wt% to 15 wt% of the cathode material's mass. Exemplarily, the amount of citric acid added can be 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%, etc., but is not limited to the listed values; other unlisted values ​​within the range are also applicable. This invention achieves optimal coating effect by controlling the amount of citric acid added.

[0032] According to a second aspect of the present invention, a cathode material prepared by any of the above-described preparation methods is provided.

[0033] The cathode material of this invention can be a rare earth element-doped and carbon-coated KV. 0.1-x Lu x OPO4@C, or KV doped with rare earth elements. 0.1-x Lu x OPO4.

[0034] It should be noted that since the cathode material provided by the present invention is prepared by the cathode material preparation method provided by the first aspect of the present invention, the beneficial effects of preparing the cathode material in any of the above embodiments are applicable to the cathode material.

[0035] According to a third aspect of the present invention, a cathode electrode is provided, comprising: the cathode material described above.

[0036] The cathode electrode in this invention may further include a conductive agent and a binder. There are no particular limitations on the types of conductive agents and binders in the cathode electrode, as long as they achieve the purpose of this invention. Exemplarily, the binder may include, but is not limited to, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), styrene-butadiene rubber (SBR), hydroxypropyl cellulose, cellulose diacetate, carboxylated polyvinyl chloride, polyvinylpyrrolidone, polyurethane, acrylated styrene-butadiene rubber, epoxy resin, or nylon. Exemplarily, the conductive agent may include, but is not limited to, conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, or any combination thereof.

[0037] The present invention does not impose any particular limitation on the preparation method of the cathode sheet; any preparation method known in the art can be used, as long as it can achieve the purpose of the present invention. Exemplarily, the preparation method includes adding the above-mentioned cathode material, conductive agent, and binder to a solvent, coating the slurry onto the current collector using a single-layer coating, double-layer coating, or multi-layer coating method, and drying to obtain the cathode sheet. Solvents include, but are not limited to, N-methylpyrrolidone (NMP), n-hexane, n-heptane, and 2,4-methylpyrrolidone (NMP). dimethyl 3 Pentanone, monochlorobenzene, xylene, toluene, isobutyl isobutyrate, anisole, cyclohexanone, 1,3,5 Trimethylbenzene, n-decane, dodecane, or methylformamide, etc.

[0038] It should be noted that since the cathode electrode provided by the present invention includes the cathode material described in the second aspect of the present invention, the beneficial effects of preparing the cathode material described in any of the above embodiments are applicable to the cathode electrode.

[0039] According to a fourth aspect of the present invention, a battery is provided, comprising: the cathode electrode described above.

[0040] In one or more embodiments, the battery is a potassium-ion battery. The battery structure may include, but is not limited to, coin cells, pouch cells, cylindrical cells, etc.

[0041] The potassium-ion battery of this invention may include an anode electrode, a cathode electrode, a separator, and an electrolyte. There are no particular limitations on the anode electrode, separator, and electrolyte in the potassium-ion battery; those skilled in the art can choose according to actual needs, as long as the purpose of this invention can be achieved. Exemplarily, the separator includes, but is not limited to, one or more of the following: glass fiber, polypropylene separator, polyethylene separator, polypropylene / polyethylene double-layer composite membrane, polypropylene / polyethylene / polypropylene triple-layer composite membrane, polyimide electrospun separator, cellulose nonwoven separator, polyethylene terephthalate nonwoven separator, and separator with ceramic coating. Exemplarily, the anode electrode includes, but is not limited to, one or more of the following: alkali metal (e.g., potassium metal sheet), graphite, and hard carbon. For example, the electrolyte includes a potassium salt and a solvent, wherein the potassium salt includes, but is not limited to, one or more of potassium hexafluorophosphate, potassium bis(fluorosulfonyl)imide, potassium bis(trifluoromethanesulfonyl)imide, potassium trifluoromethanesulfonate, and potassium tetrafluoroborate, and the solvent includes, but is not limited to, one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, ethylene glycol dimethyl ether, 1,3-dioxolane, triethyl phosphate, and fluoroethylene carbonate.

[0042] The reagents, instruments, and materials used in this invention can all be obtained through commercial channels.

[0043] The present invention will be described below through specific embodiments. It should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0044] Example 1 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.08:0.02:1 (x=0.02). Then weigh citric acid with a carbon content of 10wt% of the target product. Add all raw materials together to 150ml of deionized water and stir in an 80℃ constant temperature water bath for 4 hours. Place the obtained solution in an 85℃ forced-air drying oven and dry for 12 hours. Take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800℃ under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85℃ forced-air drying oven and bake for 12 hours to obtain the rare earth element Lu-doped and carbon-coated cathode material KV. 0.08 Lu 0.02 OPO4@C, the carbon coating thickness of this cathode material is 0.3 nm.

[0045] Example 2 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.09:0.01:1 (x=0.01). Then weigh citric acid with a carbon content of 10wt% of the target product. Add all raw materials together to 150ml of deionized water and stir in an 80℃ constant temperature water bath for 4 hours. Place the obtained solution in an 85℃ forced-air drying oven and dry for 12 hours. Take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800℃ under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85℃ forced-air drying oven and bake for 12 hours to obtain the rare earth element Lu-doped and carbon-coated cathode material KV. 0.09 Lu 0.01 OPO4@C, the carbon coating thickness of this cathode material is 0.3 nm.

[0046] Example 3 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.07:0.03:1 (x=0.03). Then weigh citric acid with a carbon content of 10wt% of the target product. Add all raw materials together to 150ml of deionized water and stir in an 80℃ constant temperature water bath for 4 hours. Place the obtained solution in an 85℃ forced-air drying oven and dry for 12 hours. Then take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800℃ under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85℃ forced-air drying oven and bake for 12 hours to obtain the rare earth element Lu-doped and carbon-coated cathode material KV. 0.07 Lu 0.03 OPO4@C, the carbon coating thickness of this cathode material is 0.3 nm.

[0047] Example 4 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.05:0.05:1 (x=0.05). Then weigh citric acid with a carbon content of 10wt% of the target product. Add all raw materials together to 150ml of deionized water and stir in an 80℃ constant temperature water bath for 4 hours. Place the obtained solution in an 85℃ forced-air drying oven and dry for 12 hours. Take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800℃ under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85℃ forced-air drying oven and bake for 12 hours to obtain the rare earth element Lu-doped and carbon-coated cathode material KV. 0.05 Lu 0.05 OPO4@C, the carbon coating thickness of this cathode material is 0.3 nm.

[0048] Example 5 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.04:0.06:1 (x=0.06). Then weigh citric acid with a carbon content of 10wt% of the target product. Add all raw materials together to 150ml of deionized water and stir in an 80℃ constant temperature water bath for 4 hours. Place the obtained solution in an 85℃ forced-air drying oven and dry for 12 hours. Take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800℃ under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85℃ forced-air drying oven and bake for 12 hours to obtain the rare earth element Lu-doped and carbon-coated cathode material KV. 0.04 Lu 0.06 OPO4@C, the carbon coating thickness of this cathode material is 0.3 nm.

[0049] Example 6 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of potassium carbonate, ammonium metavanadate, lutetium oxide, and ammonium dihydrogen phosphate according to a molar ratio of 1:0.05:0.05:1 (x=0.05). Add all raw materials together to 150 ml of deionized water and stir in a constant temperature water bath at 80°C for 4 hours. Place the resulting solution in an 85°C forced-air drying oven and dry for 12 hours. Then, take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800°C under an argon atmosphere for 12 hours. After cooling, grind the material in a planetary ball mill for 6 hours. The ratio of ball material, raw material, and deionized water is 4:1:1. Bake the ball-milled sample in an 85°C forced-air drying oven for 12 hours to obtain the rare earth element Lu-doped cathode material KV. 0.05 Lu 0.05 OPO4.

[0050] Comparative Example 1 The cathode material in this embodiment is prepared according to the following steps: First, weigh a certain amount of ammonium metavanadate, ammonium dihydrogen phosphate, and potassium carbonate in a molar ratio of 2:2:1. Then, weigh citric acid with a carbon content of 10 wt% of the target product. Add all raw materials together to 150 ml of deionized water and stir in an 80°C constant temperature water bath for 4 hours. Place the obtained solution in an 85°C forced-air drying oven and dry for 12 hours. Then, take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800°C under an argon atmosphere for 12 hours. After cooling, put the material into a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample into an 85°C forced-air drying oven and bake for 12 hours to obtain the carbon-coated cathode material KVOPO4@C. The carbon coating thickness of this cathode material is 0.3 nm.

[0051] Comparative Example 2 The cathode material in this embodiment is prepared according to the following steps: Weigh a certain amount of ammonium metavanadate, ammonium dihydrogen phosphate, and potassium carbonate in a molar ratio of 2:2:1. Add all raw materials together to 150 ml of deionized water and stir in a constant temperature water bath at 80°C for 4 hours. Place the resulting solution in an 85°C forced-air drying oven and dry for 12 hours. Then, take an appropriate amount of the dried sample and sinter it in a high-temperature tube furnace at 800°C under an argon atmosphere for 12 hours. After cooling, place the material in a planetary ball mill and grind it for 6 hours. The ratio of ball, raw material, and deionized water is 4:1:1. Place the ball-milled sample in an 85°C forced-air drying oven and bake for 12 hours to obtain the cathode material KVOPO4.

[0052] Testing and Analysis 1. Preparation of button cells: Using NMP (N-methylpyrrolidone) as a solvent, the cathode materials prepared in Examples 1-6 and Comparative Examples 1-2 were thoroughly ground with acetylene black and PVDF at a mass ratio of 80:10:10. The resulting slurry was uniformly coated onto aluminum foil with a coating mass of 0.2-0.3 g, and then dried in a vacuum drying oven at 100°C for 12 h to obtain the cathode sheet. A potassium-ion battery electrolyte was prepared using a solution of 0.8 mol / L KPF6 ethylene carbonate and propylene carbonate (mass ratio 3:7) and 1 wt% fluoroethylene carbonate. Glass fiber and potassium metal sheets were used as the potassium-ion battery separator and anode, respectively, to assemble a CR2032 type button half-cell. The battery assembly was carried out in an argon-filled glove box, with water and oxygen concentrations both less than 0.1 ppm.

[0053] 2. Electrical Performance Testing: CR2032 coin half-cells prepared using the cathode materials of Examples 1-6 and Comparative Examples 1-2 were tested using the Blue Electric CT2001A battery testing system at 2.0-4.0V (vs. K). + Within the voltage range of / K), constant current charge-discharge cycle tests were performed at room temperature (25℃) with current densities of 50mA / g, 100mA / g, and 150mA / g, respectively.

[0054] The electrochemical performance data of CR2032 coin cells prepared using the cathode materials of Examples 1-6 and Comparative Examples 1-2 are shown in the table below.

[0055]

[0056] Based on the table above, Example 6 exhibits better rate performance and higher capacity retention compared to Comparative Examples 1 and 2, indicating that rare earth element doping can expand the K-value of the cathode material. +The diffusion channels enable the cathode material to possess high energy density and excellent conductivity, thereby improving its intrinsic conductivity and thus enhancing its rate performance. Examples 1-5 show a significant improvement in rate performance and capacity retention compared to Example 6. This is because the combination of rare earth element doping and uniform carbon coating not only improves the structural stability of the cathode material but also allows for better construction of a conductive network due to the presence of numerous defects, greatly improving conductivity and effectively enhancing rate performance. While there are differences in rate performance and capacity retention between Examples 1-5, these differences are small, indicating that the amount of rare earth element doping has a relatively small impact on the rate performance and capacity retention of the cathode material.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. 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 be made to the technical solutions of the present invention, but such modifications or substitutions are all within the scope of protection of the present invention.

Claims

1. A method for producing a cathode material, characterized by, The preparation method comprises the following steps: The vanadium source, the phosphorus source, the potassium source and the rare earth element source are weighed, then dissolved in water, dried, calcined and ball milled to obtain the cathode material doped with the rare earth element.

2. The method of producing a cathode material according to claim 1, characterized in that: The molar ratio of the potassium source, the vanadium source, the rare earth element source and the phosphorus source is 1:(0.1-x):x:1, and 0 3. The method of claim 1, wherein: The vanadium source comprises at least one of vanadium dioxide, divanadium trioxide, divanadium pentoxide and ammonium metavanadate; The phosphorus source comprises at least one of ammonium phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate; The potassium source comprises at least one of potassium dihydrogen phosphate, potassium carbonate and potassium oxalate; The rare earth element source comprises at least one of lutetium source, scandium source, yttrium source, lanthanum source, cerium source, praseodymium source, neodymium source, promethium source, samarium source, europium source, gadolinium source, terbium source, dysprosium source, holmium source, erbium source, thulium source and ytterbium source.

4. The method of claim 1, wherein: The water dissolving comprises adding deionized water and stirring at 70-100 DEG C for 2-6 hours; The drying comprises baking at 80-100 DEG C in the form of air blowing for 8-16 hours; The calcination is performed in a tube furnace, the calcination temperature is increased to 800-1000 DEG C under the protection of inert gas, and the holding time is 12-18 hours; The ball milling is performed by adding water, and the mass ratio of the ball, the raw material and the deionized water is (4-6):1:

1.

5. The method of producing a cathode material according to any one of claims 1 to 4, characterized in that: The preparation steps comprise weighing the vanadium source, the phosphorus source, the potassium source, the rare earth element source and citric acid, then dissolving in water, drying, calcining and ball milling to obtain the cathode material doped with the rare earth element and coated with carbon.

6. The method of producing a cathode material according to claim 5, characterized in that: The addition amount of the citric acid satisfies that the carbon content accounts for 8wt%-15wt% of the mass of the cathode material.

7. A cathode material prepared by the preparation method in any one of claims 1-6.

8. A cathode electrode, characterized by The preparation method comprises the following steps: The cathode material in claim 7.

9. A battery, characterized by The preparation method comprises the following steps: The cathode tab in claim 8.

10. The battery of claim 9, wherein: The battery is a potassium ion battery.

Images