Lithium ion battery positive electrode material and photo-thermal recovery method and application thereof

Abstract

The invention discloses a lithium ion battery positive electrode material and a photo-thermal recovery method and application thereof. The photo-thermal recovery method comprises the following steps: uniformly mixing the waste lithium ion battery positive electrode material, a lithium source and a solvent, and performing photo-thermal lithium supplementation to obtain the regenerated lithium ion battery positive electrode material. According to the photo-thermal recovery method provided by the invention, lithium supplement and phase repair can be realized in the photo-thermal process, direct regeneration of the waste lithium ion battery positive electrode material is realized, and the components, the structure and the electrochemical performance of the recovered and repaired positive electrode material are equivalent to those of a commercial material; and moreover, the lithium supplementing time is remarkably shortened, the reaction temperature and pressure are reduced, the energy loss and regeneration cost are reduced, and the method is very environment-friendly and can be widely applied to the field of preparation of lithium ion battery positive electrodes or lithium ion batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy, and particularly relates to a lithium ion battery positive electrode material and a photothermal recovery method and application thereof. BACKGROUND

[0002] Lithium iron phosphate batteries exhibit excellent safety performance and excellent cycle stability, so that its market share in pure energy and power battery fields is steadily rising. It is estimated that the global lithium iron phosphate battery installed capacity will break through 500 GWh in 2025, accounting for more than half of the total demand for power batteries. However, due to its limited service life, the continuous active lithium loss and the degradation of the positive electrode material during the service of the battery result in that tens of thousands of waste batteries are accumulated in the market. Regenerating the waste lithium iron phosphate positive electrode by using a suitable recovery means helps to alleviate the supply chain pressure and save the battery manufacturing cost.

[0003] In the current industrial practice of recycling spent power batteries, pyrometallurgical recycling and hydrometallurgical recycling are the two most widely used mainstream technologies. However, their technical principles, operation processes, and resource consumption characteristics differ significantly, and both face economic benefit bottlenecks when adapting to the recycling of spent lithium iron phosphate batteries. From the perspective of pyrometallurgical recycling, its core logic is to separate valuable metals from other components through high-temperature smelting. The specific process usually includes pretreatment, roasting, smelting, and refining steps: first, the spent batteries need to be disassembled, crushed, and sorted to remove the shell, electrolyte, and other impurities, obtaining a mixed powder containing electrode materials; then the powder is sent to a high-temperature furnace (usually with a temperature of 1200-1600°C) for roasting, which makes the organic binder, carbon powder, and other combustible materials in the electrode material fully burn, and the metal oxides are reduced to metal elements or alloys; finally, the metal phase and slag are separated by the density difference of the molten material, and the metal phase is further refined to obtain high-purity metal or alloy products. However, this technology is a typical "energy-intensive" process - the high-temperature smelting process consumes a large amount of coal, natural gas, or electricity continuously, and the energy consumption of roasting and smelting alone accounts for more than 60% of the total energy consumption of the entire recycling process, which not only increases the unit recycling cost but also produces a large amount of carbon dioxide, sulfur dioxide, and other pollutants due to fuel combustion, posing certain environmental burdens. Hydrometallurgical recycling technology relies on the dissolution and extraction of chemical reagents to extract valuable metals, and its process is more detailed but relatively complex. This technology usually uses acid or alkaline solution as the core leaching agent, and by controlling temperature, pH value, and reaction time, the metal ions in the electrode material are fully dissolved into the solution. After leaching, insoluble impurities (such as carbon powder, aluminum foil scraps, etc.) are removed by filtration to obtain a pure metal ion mixture solution; then selective extraction is used to separate the metal ions in the solution step by step, and high-purity chemicals are prepared through precipitation, crystallization, and roasting. However, the core problem of hydrometallurgical recycling is the high consumption of reagents and the difficulty of treating wastewater, which increases equipment investment and operating costs, and if not properly handled, it can easily pollute the soil and water.

[0004] Under the background of the low economic benefits of traditional pyrometallurgical and hydrometallurgical technologies in the lithium iron phosphate battery recycling industry, the importance of developing direct recycling technology for lithium iron phosphate cathodes is increasingly prominent. The core advantage of this technology is that it does not need to completely disassemble the cathode material into single elements, but directly regenerates the waste cathode material into a cathode material that can be reused in battery production by repairing its damaged crystal structure and supplementing the lost active lithium during the cycle process, thereby fundamentally avoiding the shortcoming of traditional recycling technologies "high energy consumption, high pollution, and low benefit". At present, the most widely used core link in direct recycling technology is lithium supplementing treatment, which supplements lithium elements to the damaged lithium iron phosphate cathode material to repair its crystal structure defects caused by the continuous loss of active lithium during the cycle process and restore the electrochemical performance of the cathode material. Among them, liquid-phase hydrothermal lithium supplementing and solid-phase sintering lithium supplementing are the two most commonly used lithium supplementing methods, but both have obvious technical limitations in practical application, especially the strict requirements for reaction conditions, which restricts their industrialization promotion. The core problem of liquid-phase hydrothermal lithium supplementing technology is the dependence on high-temperature and high-pressure conditions: on the one hand, the operation of the high-pressure reactor needs to consume a large amount of electricity to maintain stable temperature and pressure, for example, the energy consumption of the hydrothermal reaction link alone is 800-1200 kWh for processing 1 ton of waste lithium iron phosphate cathode material, which is far beyond the original intention of "low energy consumption" of direct recycling technology; on the other hand, the high-temperature and high-pressure aqueous solution environment has significant safety risks, if the sealing performance of the reactor is poor, the high-temperature aqueous solution may splash due to sudden pressure drop, causing burns; at the same time, lithium-containing compounds may have side reactions with the aqueous solution at high temperatures, producing flammable and explosive gases such as hydrogen and oxygen, if the gas accumulates too much and is not discharged in time, it may cause the pressure in the reactor to abnormally rise, and even cause explosion. Solid-phase sintering lithium supplementing has even more stringent requirements for high-temperature conditions: first, the high-temperature sintering of 500-800 ℃ needs to rely on electric heating or fuel heating, which has a very high energy density, and the sintering energy consumption per ton of waste cathode material is 1500-2000 kWh, which is 1.5-2 times that of liquid-phase hydrothermal lithium supplementing, and the heating, holding, and cooling processes of the high-temperature furnace take a long time, which seriously affects the recycling efficiency. SUMMARY

[0005] The main purpose of the present application is to provide a lithium ion battery cathode material and its photothermal recycling method and application to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned application purposes, the technical solutions adopted by the present application include:

[0007] The first aspect of the present application provides a photothermal recycling method for a lithium ion battery cathode material, which comprises: uniformly mixing waste lithium ion battery cathode material, a lithium source, and a solvent, and then performing photothermal lithium supplementing to obtain regenerated lithium ion battery cathode material.

[0008] A second aspect of the invention provides a lithium-ion battery cathode material obtained by the aforementioned photothermal recovery method.

[0009] A third aspect of the present invention provides the application of the above-mentioned lithium-ion battery cathode material in the preparation of lithium-ion battery cathodes or in the field of lithium-ion batteries.

[0010] A fourth aspect of the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode comprises the aforementioned lithium-ion battery positive electrode material.

[0011] Compared with existing technologies, the present invention has at least the following beneficial effects: The photothermal recovery method provided by the present invention can realize lithium replenishment and phase repair during the photothermal process, realize the direct regeneration of decaying lithium iron phosphate, and the composition, structure and electrochemical performance of the recovered and repaired cathode material are comparable to those of commercial materials; moreover, the photothermal recovery method provided by the present invention significantly shortens the lithium replenishment time and reduces the reaction temperature and pressure, and the energy used can be solar energy, which is a green energy source, reducing energy loss and regeneration costs, and is very environmentally friendly. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the photothermal lithium replenishment process for waste lithium iron phosphate cathode materials in a typical embodiment of the present invention. Figure 2 These are X-ray photoelectron spectra of commercial lithium iron phosphate of the present invention, waste lithium iron phosphate in Example 7, and recovered lithium iron phosphate after photothermal lithium replenishment treatment in Example 7. Figure 3 This is a graph showing the first charge-discharge curves of commercial lithium iron phosphate of the present invention, waste lithium iron phosphate in Example 7, and recycled lithium iron phosphate after photothermal lithium replenishment treatment in Example 7. Figure 4 This is a cycle curve diagram of commercial lithium iron phosphate of the present invention, waste lithium iron phosphate in Example 7, and recycled lithium iron phosphate after photothermal lithium replenishment treatment in Example 7; Figure 5 This is the carbon element distribution spectrum in the energy dispersive X-ray spectrum of the recovered lithium iron phosphate after photothermal lithium replenishment treatment in Example 7 of the present invention; Figure 6This is the oxygen distribution spectrum in the energy dispersive X-ray spectrum of the recovered lithium iron phosphate after photothermal lithium replenishment treatment in Example 7 of the present invention; Figure 7 This is the iron distribution spectrum in the energy dispersive X-ray spectrum of the recovered lithium iron phosphate after photothermal lithium replenishment treatment in Embodiment 7 of the present invention; Figure 8 This is the phosphorus distribution spectrum in the energy dispersive X-ray spectrum of the recovered lithium iron phosphate after photothermal lithium replenishment treatment in Example 7 of the present invention. Detailed Implementation

[0014] In view of the problems existing in the prior art, the inventors of this invention have conducted extensive and in-depth research and have provided a lithium-ion battery cathode material and its photothermal recovery method and application.

[0015] The following will provide a further explanation of the technical solution, its implementation process, and its principles.

[0016] The first aspect of the present invention provides a photothermal recovery method for lithium-ion battery cathode material, comprising: mixing waste lithium-ion battery cathode material, lithium source and solvent evenly, and then performing photothermal lithium replenishment to obtain regenerated lithium-ion battery cathode material.

[0017] In some implementations, the photothermal recovery method for the lithium-ion battery cathode material specifically includes: mixing the lithium source with a solvent to obtain a lithium source-solvent mixed solution, then dispersing the waste lithium-ion battery cathode material into the lithium source-solvent mixed solution, performing the photothermal lithium replenishment, and obtaining regenerated lithium-ion battery cathode material.

[0018] In some implementations, the photothermal lithium replenishment temperature is 100~180°C and the time is 20~120 min.

[0019] In some implementations, the solid-liquid ratio of the waste lithium-ion battery cathode material to the lithium source-solvent mixture is 1:20~40.

[0020] In some embodiments, the lithium source content in the lithium source-solvent mixture is 10~15 mg / mL.

[0021] In some implementations, the light source used for photothermal lithium replenishment includes natural light sources and artificial light sources.

[0022] In some preferred embodiments, the natural light source includes sunlight.

[0023] In some preferred embodiments, the artificial light source includes, but is not limited to, a xenon lamp light source.

[0024] In some embodiments, the intensity of the light source used for the photothermal lithium replenishment is 150~200 mW / cm². 2 .

[0025] In some implementations, the waste lithium-ion battery cathode material includes waste lithium iron phosphate cathode material.

[0026] In some preferred embodiments, the lithium stoichiometry of lithium iron phosphate in the waste lithium iron phosphate cathode material is 0.60~0.90.

[0027] In some implementations, the lithium source includes lithium citrate, but is not limited to this.

[0028] In some embodiments, the solvent includes ethylene glycol, but is not limited to this.

[0029] Specifically, the mechanism of photothermal lithium replenishment in this invention is as follows: photogenerated electrons lower the oxidation state of Fe, reducing its reset energy barrier, and the energy provided by photothermal energy accelerates the lithium replenishment reaction. Specifically, LFP is photoexcited to generate high-energy carriers, among which trivalent iron absorbs photogenerated electrons, lowering its valence state and facilitating the reset of anti-Fe, thus opening the lithium replenishment channel. Citrate ions promptly capture photogenerated holes, extending the lifetime of photogenerated electrons. Photothermal energy provides the energy for the lithium replenishment reaction, accelerating its progress.

[0030] In some embodiments, the photothermal recovery method for the lithium-ion battery cathode material further includes: The waste lithium-ion battery is disassembled to obtain the positive electrode sheet. Then, the binder in the positive electrode sheet is dissolved with a solvent for 4-8 hours, so that the positive electrode material in the positive electrode sheet is separated from the current collector, and the waste lithium-ion battery positive electrode material is obtained.

[0031] Furthermore, the solvent includes, but is not limited to, N-methylpyrrolidone (NMP).

[0032] Furthermore, the adhesive includes, but is not limited to, polyvinylidene fluoride or polyvinylidene fluoride.

[0033] Furthermore, the current collector is made of aluminum. For example, the current collector is aluminum foil.

[0034] In some more specific embodiments, the photothermal recovery method for the lithium-ion battery cathode material specifically includes the following steps: S1. Disassemble the waste lithium-ion battery to obtain the positive electrode sheet, and then use a solvent to dissolve the binder in the positive electrode sheet for 4~8 hours to separate the positive electrode powder and the current collector, thereby obtaining the positive electrode material of the waste lithium-ion battery. S2. Subsequently, the lithium source and solvent are mixed to obtain a lithium source-solvent mixed solution. Then, the waste lithium-ion battery cathode material is dispersed into the lithium source-solvent mixed solution and subjected to light-irradiation heating to replenish lithium, thereby obtaining regenerated lithium-ion battery cathode material.

[0035] In step S1, the waste lithium-ion battery cathode material can be waste lithium iron phosphate cathode material, the solvent includes N-methylpyrrolidone, the binder includes polyvinylidene fluoride or polyvinylidene fluoride, and the current collector material includes aluminum.

[0036] In step S2, the temperature for photothermal lithium replenishment is 100~180℃, and the time is 20~120 min; the solid-liquid ratio of the waste lithium-ion battery cathode material to the lithium source-solvent mixture is 1:20~40; the lithium source content in the lithium source-solvent mixture is 10~15 mg / mL; the light source used for photothermal lithium replenishment includes natural light and artificial light, wherein the natural light source can be sunlight, and the artificial light source can be a xenon lamp, and the intensity of the light source used for photothermal lithium replenishment is 150~200 mW / cm². 2 .

[0037] An exemplary schematic diagram of the photothermal lithium replenishment process for waste lithium iron phosphate cathode materials in a typical embodiment of the present invention is shown below. Figure 1 As shown, the waste batteries are first disassembled to obtain waste lithium iron phosphate positive electrode sheets. The binder in the waste positive electrode sheets is dissolved by soaking with NMP to obtain waste lithium-ion battery positive electrode material powder. Then, it is immersed in a lithium replenishment solution for photothermal lithium replenishment to obtain recycled lithium-ion battery positive electrode material.

[0038] The second aspect of the present invention provides a lithium-ion battery cathode material obtained by the aforementioned photothermal recovery method.

[0039] In some implementations, the lithium-ion battery cathode material includes lithium iron phosphate cathode material.

[0040] The third aspect of the present invention relates to the application of the above-described lithium-ion battery cathode material in the preparation of lithium-ion battery cathodes or in the field of lithium-ion batteries.

[0041] A fourth aspect of the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode comprises the aforementioned lithium-ion battery positive electrode material.

[0042] In some implementations, the lithium-ion battery includes a lithium iron phosphate battery.

[0043] In some preferred embodiments, the lithium-ion battery comprises a lithium iron phosphate coin cell.

[0044] In some implementations, the initial capacity of the repaired cathode material of the lithium-ion battery is above 150 mAh / g.

[0045] In some implementations, the capacity retention rate of the lithium-ion battery is above 85%.

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0047] For experiments not specifically described in the examples, the procedures or conditions can be performed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available. Other unmentioned raw materials and instruments are all conventionally chosen and do not involve the core technical means of this invention.

[0048] Example 1 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0049] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 250 mg of DLFP in 10 mL of the lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:40. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 180°C and held at that temperature for 2 hours. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0050] Example 2 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0051] (2) Dissolve 150 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 15 mg / mL. Disperse 250 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:40. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 180°C and held at that temperature for 2 hours. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0052] Example 3 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0053] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 180 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0054] Example 4 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0055] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0056] Example 5 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0057] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 140 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0058] Example 6 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0059] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 20 min. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0060] Example 7 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0061] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 1 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0062] Example 8 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0063] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 170 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 1 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0064] Example 9 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0065] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 200 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 1 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0066] Example 10 This embodiment provides a photothermal recovery method for LFP (lithium iron phosphate), specifically including the following steps: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0067] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of the lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Photothermal regeneration is achieved outdoors using a condenser lens and solar light source. The light intensity was measured to be 150 mW / cm². 2 Heat it to 100 degrees Celsius. o C, incubate for 1 h. After the reaction is complete, wash repeatedly with ethanol 3 times, centrifuge and dry to collect the recovered lithium iron phosphate, denoted as RLFP.

[0068] Comparative Example 1 Comparative Example 1 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Examples 1 and 2 in that the concentration of the lithium citrate-ethylene glycol solution used in this comparative example is 5 mg / ml. (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium / iron stoichiometric ratio of lithium iron phosphate was 0.83.

[0069] (2) Dissolve 50 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 5 mg / mL. Disperse 250 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:40. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 180 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0070] Comparative Example 2 Comparative Example 2 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Examples 1 and 3 in that the solid-liquid ratio of DLFP and lithium citrate-ethylene glycol solution used in this comparative example is 1:10. (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0071] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 1000 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:10. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 180 °C and held at that temperature for 2 hours. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0072] Comparative Example 3 Comparative Example 3 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Examples 4, 6, and 7 in that the photothermal lithium replenishment time used in this comparative example is 5 minutes. (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0073] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 100 °C and held at that temperature for 5 min. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0074] Comparative Example 4 Comparative Example 4 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Examples 3, 4, and 5 in that the photothermal lithium replenishment temperature used in this comparative example is 80°C. o C: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0075] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 80 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0076] Comparative Example 5 Comparative Example 5 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Examples 3, 4, and 5 in that the photothermal lithium replenishment temperature used in this comparative example is 200°C. o C: (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0077] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Use light with an intensity of 150 mW / cm². 2 The lithium replenishment system was heated under xenon lamp illumination to 200 °C and held at that temperature for 2 h. After the reaction was complete, the system was washed three times with ethanol, centrifuged, dried, and the recovered lithium iron phosphate was collected and designated as RLFP.

[0078] Comparative Example 6 Comparative Example 6 provides a photothermal recovery method for LFP (lithium iron phosphate), which differs from Example 7 in that only electrothermal heating is used in this comparative example, without light irradiation. (1) After manually dismantling waste LFP batteries to obtain the positive electrode sheet, the electrode sheet was immersed in NMP solution for 8 h, heated and stirred at 120℃ to separate the positive electrode powder and the current collector. The LFP powder was repeatedly washed with NMP and dried in a vacuum oven to collect the waste lithium iron phosphate powder, which was denoted as DLFP. At this time, the lithium stoichiometry of lithium iron phosphate was 0.83.

[0079] (2) Dissolve 100 mg of lithium citrate in 10 mL of ethylene glycol to prepare a lithium citrate-ethylene glycol solution with a lithium citrate content of 10 mg / mL. Disperse 500 mg of DLFP in 10 mL of lithium citrate-ethylene glycol solution at a solid-liquid ratio of 1:20. Heat the lithium replenishment system to 100 °C using a heated stirring table and keep it at that temperature for 1 h. After the reaction is complete, wash the solution three times with ethanol, centrifuge and dry it to collect the recovered lithium iron phosphate, which is denoted as RLFP.

[0080] Performance testing The lithium iron phosphate cathode materials recovered in Examples 1-10 and Comparative Examples 1-6 were used to make batteries for performance testing. Specifically, lithium sheets were used as the negative electrode, the electrolyte was a 1M LiPF6 EC:DEC=1:1 lithium battery electrolyte, and the separator was a 25 μm thick lithium battery separator. The batteries were assembled into coin cells for battery testing.

[0081] The specific testing method is as follows: After the battery is assembled, it is left to stand for 8 hours. Then, it is charged and discharged three times at a constant current rate of 0.1 C, followed by a long-cycle test at a rate of 0.33 C.

[0082] Table 1 shows the relevant process parameters of the photothermal recovery methods in Examples 1-10 and Comparative Examples 1-6, as well as the relevant performance test results of batteries made from the recovered lithium iron phosphate cathode material.

[0083] Table 1. Relevant process parameters and battery performance test results for the solar thermal recovery method. Group Lithium citrate-ethylene glycol concentration (mg / ml) Solid-liquid ratio Reaction temperature (°C) o C Reaction time Intensity (mW / cm 2 ) Initial capacity of the positive electrode material after repair (mAh / g) Capacity retention rate (%) Stoichiometric ratio of lithium Example 1 10 1:40 180 2 h 150 155 85% 1.06 Example 2 15 1:40 180 2 h 150 153 94% 1.04 Example 3 10 1:20 180 2 h 150 156 97% 1.07 Example 4 10 1:20 100 2 h 150 152 95% 1.09 Example 5 10 1:20 140 2 h 150 154 95% 1.10 Example 6 10 1:20 100 20 min 150 155 93% 1.04 Example 7 10 1:20 100 1 h 150 156 90% 1.07 Example 8 10 1:20 100 1 h 170 157 91% 1.09 Example 9 10 1:20 100 1 h 200 156 93% 1.10 Example 10 10 1:20 100 1 h 150 157 92% 1.11 Comparative Example 1 5 1:40 180 2 h 150 143 75% 0.88 Comparative Example 2 10 1:10 180 2 h 150 140 80% 0.89 Comparative Example 3 10 1:20 100 5 min 150 139 79% 0.88 Comparative Example 4 10 1:20 80 2 h 150 138 80% 0.87 Comparative Example 5 10 1:20 200 2 h 150 156 93% 1.04 Comparative Example 6 10 1:20 100 1 h 0 140 83% 0.84

[0084] As shown in Table 1, comparing the performance test results of Examples 1 and 2 and Comparative Example 1, the electrochemical performance of Examples 1 and 2 is comparable, reaching the level of commercial lithium iron phosphate, while the performance of Comparative Example 1 is worse. When the concentration of lithium citrate-ethylene glycol is low (5 mg / ml, Comparative Example 1), the first-cycle performance and capacity retention of its RLFP are lower than those of commercial materials. This indicates that the concentration of lithium-containing solution and the lithium content play a crucial role in the performance of recovered lithium iron phosphate. Therefore, the solution concentrations of 10 and 15 mg / ml in Examples 1 and 2 can repair DLFP and restore its performance to the level of commercial materials.

[0085] Comparing the performance test results of Examples 1, 3, and 2, the electrochemical performance of Examples 1 and 3 is comparable, reaching the level of commercial lithium iron phosphate, while the performance of Comparative Example 2 is worse. When the solid-liquid ratio of the waste lithium iron phosphate and lithium citrate-ethylene glycol solution is low (1:10, Comparative Example 2), i.e., the amount of lithium replenishment solution used is low, the first-cycle performance and capacity retention of its RLFP are lower than those of commercial materials. This indicates that the amount of lithium-containing solution used plays a crucial role in the performance of recycled lithium iron phosphate. Therefore, the solid-liquid ratios of 1:40 and 1:20 in Examples 1 and 3 can repair DLFP and restore its performance to the level of commercial materials.

[0086] Comparing the performance test results of Examples 3, 4, and 5 with those of Comparative Examples 4 and 5, the electrochemical performance of Examples 3, 4, and 5 is comparable, all reaching the level of commercially available lithium iron phosphate. The electrochemical performance of Comparative Examples 4 and 5 is relatively poor. When adjusting the reaction temperature of the photothermal lithium replenishment system, the temperature range is 100-180°C. o C. The selected temperatures all achieved performance recovery of the recycled materials. The first-cycle performance and capacity retention of the RLFP recovered in the three examples were restored to the level of commercial materials. However, the reaction temperature in Comparative Example 4 was lower at 80°C. o At temperature C, lithium replenishment is not possible, and when the reaction temperature in Comparative Example 5 is too high, reaching 200°C... o After temperature C, the boiling point of ethylene glycol is exceeded. Even if lithium replenishment could be completed immediately, considering the safety risks, the suitable temperature is 100-180°C. o C.

[0087] Comparing the performance test results of Examples 4, 6, and 7 with Comparative Example 3, the electrochemical performance of Examples 4, 6, and 7 is comparable, recovering to the CLFP level. Comparative Example 3 exhibits poorer electrochemical performance. When the photothermal lithium replenishment time is short (5 min, Comparative Example 3), the lithium replenishment reaction cannot be fully completed, and the first-cycle performance and capacity retention of its RLFP are lower than those of commercially available materials. This indicates that the lithium replenishment time plays a crucial role in the performance of recovered lithium iron phosphate. Therefore, the lithium replenishment times of 2 h, 20 min, and 1 h in Examples 4, 6, and 7 can repair RLFP, restoring its performance to the level of commercially available materials.

[0088] Comparing the performance test results of Example 7 and Comparative Example 6, when heat energy is provided by a hot plate but there is no light (Comparative Example 6), the lithium replenishment reaction cannot be fully completed, and the first-cycle performance and capacity retention of its RLFP are lower than those of commercial materials. This indicates that light is crucial for generating photo-generated electrons to promote the lithium replenishment reaction. Therefore, the performance of the RLFP in Example 7 is restored to the level of commercial materials.

[0089] Comparing the performance test results of Examples 7, 8, and 9, the electrochemical performance of Examples 7, 8, and 9 is comparable, recovering to the CLFP level. The results indicate a light intensity of 150-200 mW / cm². 3 At that time, the capacity of the RLFP was fully recovered, proving that the suitable regenerated light intensity range is 150-200 mW / cm². 3 .

[0090] Comparing the performance test results of Examples 7 and 10, it can be seen that the electrochemical performance of Examples 7 and 10 is comparable, recovering to the CLFP level.

[0091] As a comparison, the present invention also prepared a control battery by replacing the above-mentioned RLFP with commercial lithium iron phosphate material (CLFP).

[0092] In this invention, Figure 2 The X-ray photoelectron spectra of commercial lithium iron phosphate, waste lithium iron phosphate (DLFP) in Example 7, and recycled lithium iron phosphate (RLFP) after photothermal lithium replenishment treatment in Example 7 are shown. The X-ray photoelectron spectra of DLFP and RLFP ... Figure 3 , 4 These are the electrochemical performance characterization results of CLFP, DLFP in Example 7, and RLFP in Example 7. Figure 3 and Figure 4 The figures show the charge-discharge curves and cycle curves of the battery, respectively. The results demonstrate the effectiveness of the photothermal lithium replenishment method of the present invention in repairing the electrochemical performance of DLFP. The charge-discharge capacity and cycle stability are comparable to those of commercial lithium iron phosphate materials.Figure 5 The image shown is an energy dispersive X-ray spectrum of recovered lithium iron phosphate after photothermal lithium replenishment treatment in Example 7, demonstrating that the present invention can maintain the elemental homogeneity of RLFP.

[0093] In summary, the photothermal recovery method provided by this invention can achieve lithium replenishment and phase repair during the photothermal process, enabling direct regeneration of decaying lithium iron phosphate. The composition, structure, and electrochemical performance of the recovered and repaired cathode material are comparable to those of commercial materials. Moreover, it can significantly reduce the temperature, pressure, and time of the lithium replenishment reaction, and utilizes green and pollution-free light energy. It has the advantages of simple process, excellent recovery effect, and environmental friendliness.

[0094] All aspects, embodiments, features, and examples of this invention should be considered illustrative in all respects and are not intended to limit the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention.

[0095] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0096] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A method for photothermal recovery of lithium-ion battery cathode material, characterized in that, include: After the waste lithium-ion battery cathode material, lithium source and solvent are mixed evenly, photothermal lithium replenishment is performed to obtain the regenerated lithium-ion battery cathode material.

2. The photothermal recovery method according to claim 1, characterized in that, Specifically, it includes: The lithium source and solvent are mixed to obtain a lithium source-solvent mixed solution. Then, the waste lithium-ion battery cathode material is dispersed into the lithium source-solvent mixed solution for photothermal lithium replenishment, and the lithium-ion battery cathode material is recovered.

3. The photothermal recovery method according to claim 2, characterized in that: The photothermal lithium replenishment temperature is 100~180℃, and the time is 20~120min; And / or, the solid-liquid ratio of the waste lithium-ion battery cathode material to the lithium source-solvent mixed solution is 1:20~40; And / or, the lithium source content in the lithium source-solvent mixture is 10~15 mg / mL; And / or, the light source used for the photothermal lithium replenishment includes natural light sources and artificial light sources; Preferably, the natural light source includes sunlight; Preferably, the artificial light source includes a xenon lamp light source; And / or, the intensity of the light source used for the photothermal lithium replenishment is 150~200 mW / cm². 2 .

4. The photothermal recovery method according to claim 1 or 2, characterized in that: The waste lithium-ion battery cathode material includes waste lithium iron phosphate cathode material; Preferably, the lithium stoichiometry of lithium iron phosphate in the waste lithium iron phosphate cathode material is 0.60~0.90; And / or, the lithium source includes lithium citrate; And / or, the solvent includes ethylene glycol.

5. The photothermal recovery method according to claim 1, characterized in that, Also includes: Disassemble the waste lithium-ion battery to obtain the positive electrode sheet, and then use a solvent to dissolve the binder in the positive electrode sheet for 4-8 hours to separate the positive electrode material from the current collector and obtain the positive electrode material of the waste lithium-ion battery. Preferably, the solvent comprises N-methylpyrrolidone; Preferably, the adhesive comprises polyvinylidene fluoride or polyvinylidene fluoride; Preferably, the material of the current collector includes aluminum.

6. A lithium-ion battery cathode material obtained by the photothermal recovery method according to any one of claims 1-5.

7. The lithium-ion battery cathode material according to claim 6, characterized in that: The lithium-ion battery cathode material includes lithium iron phosphate cathode material.

8. The application of the lithium-ion battery cathode material according to claim 6 or 7 in the preparation of lithium-ion battery cathodes or in the field of lithium-ion batteries.

9. A lithium-ion battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator, characterized in that: The positive electrode comprises the lithium-ion battery positive electrode material as described in claim 6 or 7.

10. The lithium-ion battery according to claim 9, characterized in that: The lithium-ion battery includes a lithium iron phosphate battery; Preferably, the lithium-ion battery includes a lithium iron phosphate coin cell; And / or, the initial capacity of the repaired cathode material of the lithium-ion battery is above 150 mAh / g; And / or, the capacity retention rate of the lithium-ion battery is above 85%.

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