A lithium bromide-mediated electrochemical sorting of whole-component closed-loop green regeneration method and system for retired lithium-ion batteries

Abstract

The application belongs to the field of power battery solid waste recycling, and discloses a kind of lithium bromide mediated electrochemical sorting of decommissioned lithium ion battery full component closed loop green regeneration method and system. With the positive black powder of decommissioned lithium ion battery as raw material, membrane electrolysis lithium bromide solution is used, and the anode contains bromine liquid oxidizes black powder lattice to realize selective delithiation, and lithium hydroxide is generated synchronously in the cathode. After lithium immersion, the solid-liquid mixture is filtered, and the lithium bromide-containing filtrate returns to the anode chamber as electrolyte for recycling; The lithium hydroxide solution enriched in the cathode chamber is taken out regularly, and carbon dioxide is introduced to precipitate lithium carbonate, and the lithium precipitation mother liquor returns to the cathode chamber for recycling. The solid phase after delithiation and the self-produced lithium carbonate are regenerated into new positive electrode material by high-temperature solid phase calcination. Based on the whole closed loop path of "anode bromine production oxidation delithiation-cathode lithium production cyclic enrichment-carbonation and lithium precipitation-solid phase calcination regeneration", no additional acid and alkali is needed in the whole process, the three waste emissions are low, and the positive black powder of decommissioned battery is regenerated in full component closed loop.

Description

Technical Field

[0001] This invention belongs to the field of solid waste recycling of power batteries, and relates to a closed-loop green recycling method and system for retired lithium-ion batteries using lithium bromide dielectric electrochemical sorting. Specifically, it relates to a green recycling method for retired lithium-ion batteries based on lithium bromide dielectric electrochemical indirect oxidation, in-situ bromine and alkali production by membrane electrolysis, and closed-loop recycling of all components. Background Technology

[0002] Lithium-ion batteries, with their core advantages of high energy density, excellent low-temperature performance, and good rate performance, are widely used in high-end new energy vehicles, high-power energy storage, and digital electronics. As power batteries enter their retirement cycle in batches, the annual amount of retired waste batteries continues to rise. The lithium, nickel, cobalt, and other metals contained within these batteries are all high-value metals. Efficient and green recycling technologies are of great significance for solving solid waste pollution, revitalizing metal resources, and reducing the production cost of cathode materials.

[0003] Currently, various technical routes have emerged for the recycling and regeneration of retired batteries. The mainstream routes include strong acid full leaching separation, chemical reduction leaching, and traditional direct electrochemical recycling. Numerous publicly available patents and literature disclose these processes; however, each existing technology has certain technical bottlenecks and cannot simultaneously achieve low-cost, highly selective, and green closed-loop mass production regeneration. To further illustrate the novelty and inventiveness of this invention, the shortcomings of existing mainstream technologies are analyzed in depth, as follows: 1. Traditional strong acid full leaching recovery technology Chinese patent CN117947274A discloses a method for the complete extraction and separation of metal elements from sulfuric acid leaching solutions of spent ternary lithium batteries. The core process involves using sulfuric acid to perform full-component strong acid leaching of retired ternary cathode black powder, simultaneously dissolving lithium, nickel, cobalt, and manganese into the liquid phase. Subsequently, a mixed extractant system of N1923+TBP+sulfonated kerosene and P507+Lix63+sulfonated kerosene, combined with multi-stage stepwise extraction and back-extraction using hydrochloric acid, nitric acid, and sulfuric acid, achieves the complete extraction and separation of nickel, cobalt, manganese, and lithium. This process is currently the mainstream industrial solution for ternary battery recycling, but it has the following drawbacks: the strong acid system lacks any metal selectivity, all valuable metals are co-soluble, a multi-stage separation system is required, the process is lengthy, equipment investment is large, and waste emissions are high, resulting in high environmental treatment costs. Chinese patent CN115064805A uses organic mixed acid leaching to extract metals such as nickel, cobalt, and manganese. After precipitating nickel, cobalt, and manganese precursors with oxalic acid solution, they are mixed with lithium source and calcined for regeneration. This further confirms that the existing acid leaching process relies on a large amount of acid reagents, which cannot avoid the industry pain points of multi-metal co-solution, high separation difficulty, high reagent cost, and serious secondary pollution. Moreover, it cannot achieve in-situ precursor forming and can only prepare single metal salts, and cannot directly regenerate cathode materials in a closed loop.

[0004] 2. Chemical reduction-assisted leaching regeneration technology Chinese patent CN116555570A discloses a wet reduction leaching method. This method involves mixing black powder with water to form a slurry, adding acid and a reducing agent, and performing preliminary leaching at room temperature. Subsequently, liquid nitrogen or dry ice is introduced to form polycrystalline ice in the slurry, and the temperature is raised to melt the ice for deep leaching. Finally, the leachate is obtained by filtration. Chinese patent CN109666799A uses sulfuric acid and a reducing agent to leach battery cathode materials. After leaching, alkali is added to adjust the pH to 10-12 to co-precipitate nickel, cobalt, and manganese. The lithium-containing solution is concentrated, and sodium carbonate is added to precipitate lithium. While these methods reduce the acid concentration, they still have the following drawbacks: additional reducing agents must be added, resulting in high reagent costs; the decomposition of the reducing agent produces a large number of byproducts, contaminating the electrolyte and metal products; reduction leaching still cannot achieve selective metal separation, resulting in the co-dissolution of multiple metals and complex subsequent purification processes; residual byproducts and organic impurities easily lead to increased lattice defects in the regenerated cathode material, resulting in rapid battery capacity decay, poor cycle stability, and unreliable product consistency.

[0005] Besides the aforementioned wet reduction leaching method, there are also reports of high-temperature reduction roasting. For example, Chinese patent CN119956118A discloses a method for preferential lithium extraction via reduction roasting, which wet-mixes black powder, carbon source, and foaming agent, and then performs reduction roasting under the protection of a mixed gas composed of carbon monoxide and carbon dioxide to convert lithium into soluble lithium salts. Finally, selective leaching of lithium is achieved through slurry water leaching. Chinese patent CN117187572A obtains positive and negative electrode mixed electrode materials from waste lithium-ion batteries through industrial inert crushing and classification. The negative electrode graphite and other components inherent in the material are used as reducing agents for in-situ self-reduction roasting. The roasting product is then filtered after ultrasonic-assisted water leaching to obtain a lithium-containing filtrate. However, all of the above technologies rely on high-temperature roasting to achieve lithium phase conversion, resulting in high energy consumption, large equipment investment, and high tail gas treatment costs. The roasting process damages the material structure, and the residue after lithium extraction cannot be converted into precursors in situ. The selective extraction of lithium still cannot avoid the co-dissolution loss of some other metals.

[0006] 3. Traditional direct electrochemical recovery technology Chinese patent CN116177575A discloses a method for preferential lithium extraction via electrochemical leaching. This method involves grinding and sieving waste cathode material, mixing it with a binder (polyvinylidene fluoride), and coating it onto a graphite sheet to create a "ternary powder electrode sheet." This electrode sheet is used as the anode, and a titanium sheet as the cathode for electrolytic oxidation, allowing lithium ions to escape from the cathode lattice and enter the electrolyte. The leachate is then heated and concentrated to prepare lithium carbonate. Chinese patent CN108808150A utilizes the structural characteristics of layered ternary electrode materials to selectively extract lithium ions from the ternary cathode active material under an applied electric field. A precipitant is used for precipitation and recovery, and the lithium-deficient ternary cathode material is used as a catalyst for the oxygen evolution reaction. However, direct electrochemical recovery technology has the following problems: the electrode fabrication process is cumbersome, consumes a large amount of materials, and has high production costs; during electrolysis, the electrodes are prone to cracking, powdering, and uneven conductivity, leading to incomplete delithiation, localized over-oxidation, and significant metal leaching and loss; the cell voltage fluctuates greatly, energy consumption is high, and the single-batch processing capacity is limited, making it only suitable for small-scale laboratory tests and unable to achieve industrial mass production. Furthermore, related technologies lack an in-situ metal separation mechanism, resulting in a mixture of multiple metals after delithiation, making it impossible to directly obtain high-purity cathode precursors.

[0007] 4. Existing electrochemical indirect oxidation technology (closest to this invention but with key differences) Chinese patent CN118563107A discloses a method for recycling metal elements in waste battery cathode materials based on the electrolytic reaction of alkali metal chloride aqueous solution. The method involves placing the waste cathode material in an electrolytic alkali metal chloride aqueous solution system. Chlorine gas generated at the anode reacts with hydrogen gas generated at the cathode to produce hydrochloric acid for leaching the cathode material, while hydroxide ions at the cathode are used to precipitate transition metals. Although this process introduces indirect electrochemical means, its core is still the use of chlorine gas generated at the anode to react with hydrogen gas generated at the cathode to prepare hydrochloric acid for leaching the cathode material. Essentially, it belongs to a chlorine-assisted acid leaching route, rather than directly oxidizing and delithiating lithium using active chlorine species at the anode. Furthermore, this process has related engineering defects: chloride ions are a strictly controlled impurity in battery electrode materials, requiring a complex dechlorination process for lithium salt purification; chlorine gas is highly toxic, necessitating high investment in tail gas treatment equipment; and the lack of a closed-loop recycling system results in significant losses of reagents and materials, high wastewater production, and limited industrialization value. Currently, there are few reports on the recycling of waste batteries related to electrochemical indirect oxidation technology. Moreover, the relevant solutions lack in-situ metal precipitation and retention mechanisms, closed-loop salt solution circulation, and in-situ precursor forming and regeneration chains. Furthermore, the process flow is incomplete and cannot achieve closed-loop regeneration of all battery components.

[0008] In summary, current retired battery recycling technologies face numerous bottlenecks. For example, mainstream processes rely on strong acids and other reagents, resulting in high reagent consumption, severe pollution, and failure to meet the requirements of green industry development. Furthermore, they cannot achieve precise selective separation of lithium, often suffer from polymetallic co-dissolution, and involve complex separation processes, high material losses, and poor product purity. Therefore, there is an urgent need to develop a green recycling technology that requires no large amounts of exogenous acids, alkalis, or organic solvents, offers high selectivity, and allows for closed-loop recycling. Summary of the Invention

[0009] The purpose of this invention is to address the multiple technical bottlenecks in existing retired lithium-ion battery recycling processes, such as reliance on large amounts of exogenous reagents like strong acids, reducing agents, and organic extractants, as well as the significant impurities and difficulty in controlling oxidation in chlorine-based electrochemical recycling routes. This invention provides a closed-loop green regeneration method and system for all components of retired lithium-ion batteries using lithium bromide-mediated electrochemical separation. It constructs a combined system of pure lithium bromide electrolyte membrane electrolysis and external oxidation, leveraging the unique electrochemical advantages of bromide ions, anode-cathode partitioning coupling, and dual closed-loop circulation to achieve precise selective separation of lithium and closed-loop circulation of the bromide electrolyte throughout the process. This solves the technical problems of high pollution, high reagent loss, and difficulty in controlling product impurities in traditional processes, enabling low-cost, green, and large-scale mass production regeneration of retired batteries.

[0010] The technical solution of this invention is: This invention provides a closed-loop green regeneration method for all components of retired lithium-ion batteries through lithium bromide dielectric electrochemical sorting, comprising the following steps: S1. Raw material pretreatment: After deep discharge, mechanical disassembly, crushing and sorting, and impurity removal, retired lithium-ion batteries are used to obtain pure positive electrode black powder. S2. Membrane electrolysis for bromine and lithium hydroxide production: A lithium bromide solution is prepared and fed into the anode chamber of a membrane-divided dual-chamber electrolyzer. A low-concentration lithium hydroxide solution is initially added to the cathode chamber as a supporting electrolyte. Bromine ions are electro-oxidized at the anode to generate a bromine-containing solution. An alkaline lithium hydroxide solution is generated in situ at the cathode. S3, bromine oxidation delithiation and precipitation: The bromine-containing solution at the anode is introduced into the oxidation precipitation reactor and mixed with the black powder at the cathode. The liquid-phase bromine species oxidize the material lattice to achieve selective removal of lithium ions, obtaining an extraction slurry composed of a lithium-containing solution and a delithiated solid phase. After the bromine oxidation delithiation reaction is completed, a portion of the cathode lithium hydroxide alkaline solution is introduced to adjust the pH of the oxidation precipitation reactor system, so that the dissolved iron metal ions or nickel metal ions, cobalt metal ions, and manganese metal ions react with hydroxide ions to generate metal hydroxide precipitates. S4. Solid-liquid separation and filtrate recirculation: The solid-liquid mixture in the oxidation precipitation reactor is discharged as a whole and filtered to obtain a solid phase and a lithium bromide-containing filtrate; the solid phase is a mixture of the delithiated cathode material and the metal hydroxide precipitate, and the lithium bromide-containing filtrate is returned to the anode chamber of step S2 as an electrolyte for recycling. S5. Carbonation precipitation of lithium and mother liquor reuse: The lithium ion concentration in the cathode chamber of step S2 is monitored in real time. When the lithium ion concentration reaches the set threshold, the lithium hydroxide alkaline solution of the cathode is taken out and preheated. Carbon dioxide gas is then introduced to carry out the carbonation reaction to generate lithium carbonate precipitate. After filtration, washing and drying, lithium carbonate product is obtained. The lithium precipitation mother liquor is returned to the cathode chamber of step S2 for recycling. S6. Closed-loop regeneration of cathode material: After drying the solid phase obtained in step S4, it is precisely mixed with the lithium carbonate obtained in step S5 according to the target cathode material stoichiometric ratio, and then calcined at high temperature in a certain atmosphere. After cooling, crushing and sieving, the recycled cathode material is obtained, thus completing the closed-loop resource recycling of all components of retired batteries.

[0011] Furthermore, in step S1, the retired lithium-ion battery is a lithium iron phosphate battery or a nickel-cobalt-manganese ternary lithium-ion battery.

[0012] Further, in step S2, the dual-chamber electrolytic cell is a corrosion-resistant electrolytic cell, and the membrane is selected as a diaphragm for caustic soda production or an alkali-resistant cation exchange membrane; the anode is a shape-stable bromine-electrode electrode, and the cathode is selected as one of a titanium electrode, a stainless steel electrode, a nickel electrode, or a graphite electrode.

[0013] Further, in step S2, the mass fraction of the lithium bromide solution is 1%~15%, and the mass fraction of the lithium hydroxide solution is 0.1%~5%; the membrane electrolysis voltage is 1.6~2.4 V, and the electrolysis is carried out at room temperature with stirring and cycling for 1~8 h; during the electrolysis process, the lithium ions dissolved from the positive electrode black powder migrate to the anode chamber with the anolyte, and migrate through the membrane to the cathode chamber under the drive of the electric field, where they combine with the hydroxide ions generated in situ at the cathode to continuously enrich lithium hydroxide.

[0014] Furthermore, in step S3, the solid-liquid ratio of the positive electrode black powder to the bromine-containing solution in the oxidation precipitation reactor is 20~200 g / L; the pH of the oxidation precipitation reactor is controlled to 10~13, and the precipitation reaction time is 0.5~3 h.

[0015] Furthermore, in step S5, the set threshold for lithium ion concentration is ≥10 g / L, the preheating temperature is 70~95℃, and the pH of the reaction endpoint of the carbonation process is controlled to be 9.5~11.5.

[0016] Further, in step S6, when the raw material is the positive electrode black powder of lithium iron phosphate battery, additional phosphorus and carbon sources need to be added. Lithium carbonate and solid phase are mixed at a Li:Fe molar ratio of 1.00~1.05:1, the amount of carbon source added is 5%~15% of the molar amount of iron, and phosphorus is added at a Fe:P molar ratio of 1:1. The calcination temperature is 600~800℃, the calcination time is 2~8 h, and the calcination atmosphere is nitrogen or argon. When the raw material is the positive electrode black powder of ternary lithium-ion battery, additional carbon source needs to be added. Lithium carbonate and solid phase are mixed at a Li / (Ni+Co+Mn) molar ratio of 1.02~1.08:1, and the amount of carbon source added is 3%~15% of the total molar amount of transition metals (Ni+Co+Mn). The material is reduced and calcined at 500~650℃ for 1~4 h in an inert atmosphere of nitrogen or argon, and then switched to an air or pure oxygen atmosphere for calcination at 800~950℃ for 3~10 h. h.

[0017] Further, in step S6, the carbon source is selected from at least one of glucose, sucrose, starch, citric acid, and acetylene black; the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, and phosphoric acid.

[0018] Another aspect of the present invention provides a system for realizing the above-mentioned closed-loop green regeneration method of retired lithium-ion batteries with lithium bromide dielectric electrochemical separation, comprising: a membrane electrolysis unit, an oxidation precipitation reactor, a first filtration unit, a cathode liquid preheating buffer tank, a carbon dioxide pressure stabilization gas supply unit for a carbonation reactor, a second filtration unit, a mixing and calcination unit, and a parameter configuration module built into the system. The membrane electrolysis unit includes an anode chamber and a cathode chamber of a dual-chamber electrolyzer. The anode chamber is equipped with an anolyte outlet and an anode filtrate return feed inlet. The cathode chamber is equipped with an online lithium-ion concentration monitoring module, a cathode liquid outlet, and an alkali distribution branch. The system has a built-in interlock valve that opens only when the lithium-ion concentration in the cathode chamber is ≥ a set threshold. The oxidation precipitation reactor is equipped with an online pH monitoring module and a stirring device. The oxidation precipitation reactor has an anolyte inlet, a positive electrode black powder feeding port, a discharge port and an alkaline solution inlet. The anolyte inlet is connected to the anolyte outlet of the anode chamber through a pipeline, and the alkaline solution inlet is connected to the alkaline solution distribution branch of the cathode chamber through a pipeline. The first filtration unit is provided with a solid-liquid mixture inlet, a solid phase outlet and a liquid phase outlet; the solid-liquid mixture inlet is connected to the outlet of the oxidation precipitation reactor through a pipeline, and the liquid phase outlet is connected to the anode filtrate return inlet through a first reflux pipeline, forming a closed-loop circulation loop of lithium bromide filtrate. The inlet of the cathode liquid preheating buffer tank is connected to the cathode liquid outlet of the cathode chamber via a pipeline; The carbonation reactor is equipped with a carbon dioxide pressure stabilizing gas supply unit. Its lithium-rich liquid inlet is connected to the outlet of the cathode liquid preheating buffer tank through a pipeline. The carbonation reactor is equipped with a carbon dioxide inlet pipeline and gas flow regulation device, temperature monitoring and heating device, and pH online monitoring module. The feed inlet of the second filtration unit is connected to the discharge outlet of the carbonation reactor through a pipeline, and the liquid phase outlet is connected to the feed inlet of the cathode chamber through the second reflux pipeline, forming a closed-loop circulation loop of lithium precipitation mother liquor. The mixing and roasting unit includes a drying device, a ball milling device, and a high-temperature roasting furnace. The ball milling device is equipped with a lithium carbonate inlet, a carbon source inlet, and a phosphorus source inlet for lithium iron phosphate regeneration. The inlet of the drying device is connected to the solid phase outlet of the first filtration unit, and the outlet of the drying device and the solid phase outlet of the second filtration unit are connected to the inlet of the ball milling device. The outlet of the ball milling device is connected to the inlet of the high-temperature roasting furnace. The system's built-in parameter configuration module includes a cathode liquid lithium ion concentration setting threshold unit, an oxidation precipitation reactor pH interlock control unit, a carbonation reactor pH, temperature, and aeration control unit, and a calcination atmosphere and temperature / time parameter configuration unit. All equipment is equipped with automatic interlocking actuators.

[0019] The overall concept and multiple core synergistic effects of this invention are analyzed as follows: The first layer utilizes a dedicated membrane electrolysis-external oxidation combined system for bromide ions, avoiding the inherent defects of chloride-based media. This invention employs lithium bromide as the sole circulating medium throughout the process, constructing a combined system of "membrane electrolysis for bromine production - anolyte export to an independent oxidation precipitation reactor - external oxidation for lithium removal." Since the oxidation potential of bromide ions is lower than that of chloride ions, active bromine species are preferentially generated during electrolysis, significantly suppressing the oxygen evolution side reaction and improving energy utilization efficiency. The bromine oxidation products are liquid at room temperature, making them less prone to volatilization and escape, resulting in a long-term stable oxidant concentration in the electrolyte. The anode chamber is free of black powder solid phases, avoiding engineering problems such as solid phase deposition clogging the membrane surface and scratching the diaphragm. Simultaneously, the oxidant concentration and export rate can be precisely controlled in the anolyte, achieving precise regulation of the oxidation-delithiation reaction. The lithium battery industry has a high tolerance for bromine impurities; self-produced lithium carbonate only requires simple impurity removal to meet battery-grade standards, eliminating the need for a deep impurity removal process.

[0020] The second step involves in-situ alkali production via anode-cathode partitioning, achieving selective lithium separation and impurity retention. This invention utilizes a dual-chamber electrolyzer to construct an in-situ acid-base control system: at the anode, bromide ions are oxidized to generate active bromine, which is then exported to an independent oxidation precipitation reactor. This active bromine is then directionally stripped of lithium ions from the crystal lattice, allowing them to enter the liquid phase (completed in the independent oxidation precipitation reactor, separate from the electrolyzer); at the cathode, water electrolysis continuously generates hydroxide ions, achieving effective enrichment of lithium in the cathode chamber, resulting in a high-concentration lithium cathode solution. After oxidation, a portion of the cathode alkali solution is introduced to adjust the pH of the oxidation precipitation reactor system. This allows trace amounts of metal ions dissolved from the anode solution to combine with hydroxide ions to form hydroxide precipitates, which are completely retained in the solid filter cake. Lithium is retained solely in the bromide filtrate. Precise phase separation of lithium from other metals is achieved in a single solid-liquid separation step, eliminating the need for complex separation processes such as extraction, multi-stage pH adjustment, and stepwise precipitation. The in-situ generated hydroxide has a uniform elemental composition and is free of external impurities, making it a direct precursor for the regenerated cathode.

[0021] The third layer: a dual closed-loop circulation system to achieve internal circulation of the bromide salt medium. This invention constructs a dual closed-loop circulation circuit for the anolyte and catholyte: ① Anolyte circulation: After oxidation, delithiation, and precipitation, the lithium bromide-containing filtrate is directly returned to the anode chamber as an electrolyte for reuse. Bromine ions only act as an "oxidation medium" throughout the process and are not consumed themselves; ② Catholyte circulation: The lithium hydroxide solution enriched in the cathode chamber is periodically removed and carbonated with carbon dioxide to precipitate lithium. The lithium precipitation mother liquor is returned to the cathode chamber as a supporting electrolyte for recycling. Except for bromide ions, the above dual closed-loop system does not introduce any other external impurities and produces no large amounts of waste liquid or waste salt, resulting in low environmental treatment costs.

[0022] The fourth stage: Integrated regeneration of delithiation solid phase and self-produced lithium carbonate with precise lithium matching and high-temperature roasting. The solid filter cake after delithiation is directly used as the precursor substrate, and the molar ratio with the self-produced battery-grade lithium carbonate is precisely controlled to compensate for high-temperature lithium volatilization. Trace carbon sources are uniformly dispersed, and high-temperature solid-phase roasting directly synthesizes new cathode materials, suitable for both lithium iron phosphate and ternary cathode material systems. The entire process involves internal material recycling, with all metals such as lithium being converted into battery-grade cathode raw materials, fully integrating the entire process of "waste battery dismantling - selective delithiation - lithium recovery - cathode regeneration".

[0023] The advantages and positive effects of this invention are: (1) The medium system is green and low in impurities, and the cost of lithium salt purification is greatly reduced: the whole process adopts a bromide circulation system, and there is no risk related to chloride ions; the self-produced lithium carbonate only needs simple impurity removal, saving the complex deep impurity removal process.

[0024] (2) The electrochemical reaction is stable and controllable with low energy consumption: the oxidation potential of bromide ions is lower, which greatly suppresses the side reaction of electrolytic oxygen; the bromine product is not easily volatilized and lost, and the amount of anolyte and the concentration of oxidant can be precisely controlled.

[0025] (3) One-step separation of lithium from other metals eliminates the need for multiple complex separation processes: in-situ alkali production at the cathode coupled with active bromine for directional delithiation, and one-step solid-liquid separation can achieve lithium entering the liquid phase, dissolving impurity metal ions, co-precipitating and retaining them in the solid phase.

[0026] (4) No external acids, alkalis and organic solvents are involved in the entire process: The main external material used in this process is carbon dioxide introduced in the lithium carbonate precipitation step, which eliminates the consumption of large amounts of reagents and secondary pollution from the source.

[0027] (5) Dual closed-loop circulation system, internal material circulation: both anolyte and catholyte are recycled in a closed loop. Except for bromide ions, no other foreign impurities are introduced throughout the process, and there is no large amount of waste liquid or waste salt discharged.

[0028] (6) It only involves conventional and mature unit operations with low industrialization risk: membrane electrolysis, oxidation, solid-liquid separation, lithium carbonate precipitation, and high-temperature roasting are all mature unit operations in the chemical industry. There are no special harsh working conditions, and they are easy to scale up and mass-produce.

[0029] (7) It has strong universality and is compatible with the entire lithium iron phosphate and nickel cobalt manganese ternary systems: there is no need to select high-quality raw materials or to make black powder sheets. It can be used for retired cathode black powder of both lithium iron phosphate and nickel cobalt manganese ternary systems, and has a wide range of applications. Attached Figure Description

[0030] Figure 1 This is a flowchart of the closed-loop green regeneration method for all components of retired lithium iron phosphate power batteries using lithium bromide-mediated electrochemical sorting, as described in Example 1.

[0031] Figure 2 This is a photograph of the solid phase obtained after delithiation in Example 1.

[0032] Figure 3 The image shows the XRD pattern of the solid phase obtained after delithiation in Example 1.

[0033] Figure 4 This is a photograph of lithium carbonate obtained by carbonation precipitation in Example 1.

[0034] Figure 5 The image shows the XRD pattern of lithium carbonate obtained by carbonation precipitation in Example 1.

[0035] Figure 6 This is a photograph of the regenerated lithium iron phosphate cathode material obtained by high-temperature calcination in Example 1.

[0036] Figure 7 The image shows the XRD pattern of the regenerated lithium iron phosphate cathode material obtained by high-temperature calcination in Example 1.

[0037] Figure 8 The image shows the XRD pattern of the solid phase obtained after delithiation in Example 3.

[0038] Figure 9 The image shows the XRD pattern of lithium carbonate obtained by carbonation precipitation in Example 3.

[0039] Figure 10 The image shows the XRD pattern of the regenerated NCM523 cathode material obtained by high-temperature calcination in Example 3. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0041] Example 1: Closed-loop regeneration of cathode black powder from retired lithium iron phosphate power batteries A closed-loop green regeneration method for all components of retired lithium iron phosphate power batteries via lithium bromide-mediated electrochemical sorting is described below. Figure 1 The specific steps are as follows: S1. Raw Material Pretreatment: Retired commercial lithium iron phosphate power batteries are subjected to deep discharge with sodium chloride solution, followed by mechanical disassembly, crushing, and air separation to remove impurities such as the outer shell, separator, and copper and aluminum foil, yielding pure cathode black powder. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis revealed that the black powder contains 3.92% lithium and 31.2% iron.

[0042] S2. Membrane electrolysis for bromine and lithium hydroxide production: A titanium alloy membrane-divided dual-chamber electrolytic cell is used. The cathode and anode chambers are separated by a perfluorosulfonic acid-perfluorocarboxylic acid composite cation exchange membrane (Asahi Glass product). The anode is a titanium-based ruthenium-iridium stabilizing bromine electrode, and the cathode is a stainless steel electrode. An 8% (w / w) lithium bromide solution is prepared and introduced into the anode chamber, while a 1% (w / w) lithium hydroxide solution is injected into the cathode chamber as a supporting electrolyte. Electrolysis is carried out at a constant voltage of 2.0 V and at room temperature with stirring for 2 hours.

[0043] S3. Oxidative Lithium Removal and Precipitation: All the bromine-containing solution from the anode chamber of the electrolytic cell is transferred to an independent oxidative precipitation reactor. The cathode black powder obtained in step S1 is added to the oxidative precipitation reactor at a solid-liquid ratio of 80 g / L between the cathode black powder and the bromine-containing solution. The reaction is carried out at room temperature with stirring for 3 hours. The liquid-phase bromine species oxidize the material lattice to selectively remove lithium ions, resulting in an extraction slurry composed of a lithium-containing solution and a delithiated solid phase. After oxidative lithium removal is complete, a portion of the lithium hydroxide alkaline solution produced in the cathode chamber is introduced to adjust the pH of the oxidative precipitation reactor to approximately 11.5, causing the dissolved iron ions to precipitate as ferric hydroxide. Stirring continues for 1 hour.

[0044] S4. Solid-liquid separation and filtrate recirculation: The solid-liquid mixture in the oxidation precipitation reactor is discharged as a whole and filtered to obtain a solid phase and a lithium bromide-containing filtrate; the obtained solid phase is a mixture of the delithiated cathode material and iron hydroxide precipitate; the lithium bromide-containing filtrate is returned to the anode chamber in step S2 for recycling.

[0045] S5. Carbonation precipitation of lithium and mother liquor reuse: Circulate steps S2 to S4, and monitor the lithium ion concentration in the cathode chamber of step S2 in real time. When the lithium ion concentration in the cathode chamber reaches 15.6 g / L (≥10 g / L threshold), take out the cathode lithium hydroxide alkaline solution, preheat it to 85℃, and introduce carbon dioxide to carry out the carbonation reaction. Control the endpoint pH≈10.5 to generate lithium carbonate precipitate, filter, wash, and dry to obtain lithium carbonate product; the lithium precipitation mother liquor is returned to the cathode chamber for recycling.

[0046] S6. Regeneration of lithium iron phosphate cathode: After drying the solid phase obtained in step S4 at 60°C, it is mixed with the self-produced lithium carbonate in step S5 at a Li:Fe molar ratio of 1.03:1. Carbon source (glucose) and phosphorus source (ammonium dihydrogen phosphate) are added. The amount of carbon source added is 5% of the molar amount of iron element, and the amount of phosphorus source added is made up according to the iron-phosphorus molar ratio of 1:1 in the target lithium iron phosphate chemical formula. The mixture is ball-milled for 3 h; calcined at 700°C for 6 h under nitrogen atmosphere, cooled, crushed and sieved to obtain the regenerated lithium iron phosphate cathode material.

[0047] The physical image and XRD pattern of the solid phase obtained after delithiation in step S4 are shown below. Figure 2 and Figure 3 The physical image and XRD pattern of the lithium carbonate obtained in step S5 are shown below. Figure 4 and Figure 5 Physical images and XRD patterns of the regenerated lithium iron phosphate cathode material obtained by high-temperature calcination are shown below. Figure 6 and Figure 7 Testing revealed that the main phase purity of the recycled lithium iron phosphate cathode material was 95.8%. After assembling into coin cells, the first charge-discharge test at a 0.1 C rate showed an initial discharge capacity of 154.2 mAh / g.

[0048] Example 2: Closed-loop regeneration of cathode black powder from retired lithium iron phosphate batteries (under different process conditions) The process flow is the same as in Example 1. The specific steps are as follows: S1. Raw material pretreatment: Same as step S1 in Example 1. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis revealed that the lithium content in the black powder was 3.85%, and the iron content was 30.5%.

[0049] S2, membrane electrolysis for bromine and lithium hydroxide production: The only difference from step S2 in Example 1 is that the cathode chamber and anode chamber are separated by a Dinora PMX asbestos-free perfluorinated composite membrane, and the cathode is a graphite electrode; the mass fraction of lithium bromide solution is 12%, and the mass fraction of lithium hydroxide solution in the cathode chamber is 1.5%; constant voltage 2.2 V, cyclic electrolysis at room temperature for 5 h.

[0050] S3, bromine oxidation delithiation and precipitation impurity removal: The only difference from step S3 in Example 1 is that the solid-liquid ratio of the positive electrode black powder to the bromine-containing liquid at the anode in the oxidation precipitation reactor is 120 g / L, and the reaction is carried out at room temperature for 4 h; the cathode alkaline solution is introduced to adjust the pH to about 12.0 so that the iron ions are completely precipitated, and stirring is continued for 1.5 h.

[0051] S4. Solid-liquid separation and filtrate reflux: Same as step S4 in Example 1.

[0052] S5, Lithium carbonate precipitation and mother liquor reuse: The only difference from step S5 in Example 1 is that the cathode liquid is preheated to 90°C and carbon dioxide is introduced to control the final pH to ≈11.0.

[0053] S6, Lithium iron phosphate cathode regeneration: The only difference from step S6 in Example 1 is that the Li:Fe molar ratio is 1.05:1, the carbon source is sucrose, and the amount added is 10% of the molar amount of iron; the phosphorus source is phosphoric acid; calcination is carried out at 750°C for 5 h.

[0054] The purity of the main phase of the recycled lithium iron phosphate cathode material was 95.3% as tested. The initial discharge capacity was 155.5 mAh / g when tested with a coin cell using the same method as in Example 1.

[0055] Example 3: Closed-loop regeneration of cathode black powder from retired nickel-cobalt-manganese ternary batteries (NCM523 raw material) The process flow is the same as in Example 1. The specific steps are as follows: S1. Raw material pretreatment: The only difference from step S1 in Example 1 is that the retired battery is a commercial NCM523 ternary lithium battery. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis showed that the lithium content in the black powder was 6.21%, and the molar ratio of Ni, Co, and Mn was 5:2:3.

[0056] S2, membrane electrolysis to produce bromine and lithium hydroxide: The only difference from step S2 in Example 1 is that a 10% lithium bromide solution is prepared and introduced into the anode chamber, and a 2% lithium hydroxide solution is injected into the cathode chamber; constant voltage 2.0 V, cyclic electrolysis at room temperature for 2.5 h.

[0057] S3, bromine oxidation delithiation and precipitation impurity removal: The only difference from step S3 in Example 1 is that NCM523 black powder is added to the oxidation precipitation reactor at a solid-liquid ratio of 100 g / L between the positive electrode black powder and the bromine-containing liquid at the anode, and the reaction is stirred at room temperature for 4 h; the cathode lithium hydroxide alkaline solution is introduced to adjust the pH to about 11.5, so that the dissolved nickel, cobalt and manganese co-precipitate in the form of hydroxides, and stirring is continued for 1.5 h.

[0058] S4. Solid-liquid separation and filtrate reflux: Same as step S4 in Example 1.

[0059] S5, Lithium carbonate precipitation and mother liquor reuse: Same as step S5 in Example 1.

[0060] S6. Ternary cathode regeneration: After drying the solid phase obtained in step S4 at 60°C, it is mixed with lithium carbonate from step S5 at a ratio of Li / (Ni+Co+Mn)=1.05:1, and glucose carbon source is added in an additional amount of 8% of the total molar amount of transition metals (Ni+Co+Mn). The mixture is reduced and calcined at 600°C for 2 h under a nitrogen atmosphere, and then switched to an air atmosphere for oxidative calcination at 850°C for 7 h. After cooling, crushing and sieving, the regenerated NCM523 cathode material is obtained.

[0061] The XRD pattern of the solid phase obtained after delithiation in step S4 is shown in Figure 1. Figure 8 The XRD pattern of lithium carbonate obtained by carbonation precipitation is shown in [reference needed]. Figure 9 The XRD pattern of the regenerated NCM523 cathode material obtained by high-temperature calcination is shown below. Figure 10 Testing revealed that the purity of the main phase of the regenerated NCM523 cathode material was 94.2%. A coin cell test, conducted using the same method as in Example 1, showed an initial discharge capacity of 157.8 mAh / g.

[0062] Example 4: Closed-loop regeneration of cathode black powder from retired nickel-cobalt-manganese ternary batteries (NCM811 raw material) The process flow is the same as in Example 1. The specific steps are as follows: S1. Raw material pretreatment: The only difference from step S1 in Example 1 is that the retired battery is a commercial NCM811 high-nickel ternary power battery. Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis showed that the lithium content in the black powder was 6.45%, and the molar ratio of Ni, Co, and Mn was 8:1:1.

[0063] S2, membrane electrolysis to produce bromine and lithium hydroxide: The only difference from step S2 in Example 2 is that the mass fraction of the lithium hydroxide solution in the cathode chamber is 1%, and the constant voltage is 2.3 V.

[0064] S3, bromine oxidation delithiation and precipitation impurity removal: The only difference from step S3 in Example 1 is that NCM811 black powder is added to the positive electrode black powder and the bromine-containing liquid at a solid-liquid ratio of 150 g / L in the oxidation precipitation reactor and reacted at room temperature for 5 h; the pH is adjusted to about 11.5 by introducing the cathode lithium hydroxide alkaline solution to precipitate Ni / Co / Mn hydroxides and stirring is continued for 2 h.

[0065] S4. Solid-liquid separation and filtrate reflux: Same as step S4 in Example 1.

[0066] S5, Carbonation precipitation of lithium and recycling of mother liquor: The only difference from step S5 in Example 1 is that the cathode lithium hydroxide alkaline solution is preheated to 90°C and carbon dioxide is introduced to control the final pH to approximately 11.0.

[0067] S6, Ternary cathode regeneration: The only difference from step S6 in Example 3 is that the Li / (Ni+Co+Mn) molar ratio is 1.08:1, and the amount of carbon source sucrose added is 10% of the total molar amount of transition metals (Ni+Co+Mn); reduction roasting at 650℃ under nitrogen atmosphere for 3 h, and oxidation roasting at 920℃ under pure oxygen atmosphere for 6 h.

[0068] The purity of the main phase of the regenerated NCM811 cathode material was 93.1% after testing. The initial discharge capacity was 183.5 mAh / g after testing with a coin cell, using the same method as in Example 1.

[0069] Example 5 A system for implementing the lithium bromide-mediated electrochemical separation method for the closed-loop green regeneration of retired lithium-ion batteries, comprising a membrane electrolysis unit, an oxidation precipitation reactor, a first filtration unit, a cathode liquid preheating buffer tank, a carbonation reactor with a carbon dioxide pressure stabilization and gas supply unit, a second filtration unit, a mixing and calcination unit, and a system-built-in parameter configuration module. Each unit is equipped with an interlocking automatic control mechanism, thus establishing a complete universal closed-loop regeneration production line for retired lithium iron phosphate batteries or nickel-cobalt-manganese ternary lithium-ion batteries. The structural and pipeline coupling relationships of each unit are as follows: The membrane electrolysis unit includes an anode chamber and a cathode chamber of a dual-chamber electrolyzer separated by a perfluorosulfonic acid-perfluorocarboxylic acid composite cation exchange membrane or an asbestos-free perfluoro composite membrane for caustic soda production. It is equipped with an anode electrolyte preparation tank and a cathode support alkali preparation tank, corresponding to the feed to the anode and cathode chambers, respectively. A titanium-based ruthenium-iridium stabilizing bromine electrode is installed in the anode chamber, and a stainless steel or graphite electrode is installed in the cathode chamber. The anode chamber has an anode liquid outlet and an anode filtrate return feed inlet. The bromine-containing solution produced from the anode is unidirectionally transported to the oxidation precipitation reactor via pipeline. The cathode chamber is equipped with an online lithium ion concentration monitoring module, an alkali distribution branch, and a cathode liquid outlet. The system interlock valve only opens the cathode liquid outlet valve when the cathode lithium concentration is ≥10 g / L. The lithium hydroxide alkali solution produced from the cathode chamber is transported in two routes: one to the oxidation precipitation reactor to adjust the pH and precipitate metal impurities, and the other to the cathode liquid preheating buffer tank.

[0070] The oxidation precipitation reactor is equipped with an online pH monitoring module and a stirring device. It has an anolyte inlet, a cathode black powder feed port, a discharge port, and an alkali inlet. The anolyte feed pipe connects to the anolyte outlet of the membrane electrolysis unit, and the alkali inlet connects to the alkali distribution branch of the cathode chamber via a pipe. The first filtration unit has a solid-liquid mixture inlet, a solid phase outlet, and a liquid phase outlet. The discharge port at the bottom of the oxidation precipitation reactor connects to the solid-liquid mixture inlet of the first filtration unit via a pipe. The first filtration unit has two discharge paths: the liquid phase outlet connects to the anolyte reflux feed port via a first return pipe, forming a closed-loop circulation circuit for the lithium bromide electrolyte; and the solid phase outlet connects to the drying device of the mixing and calcination unit.

[0071] The carbonation reactor is equipped with an independent carbon dioxide pressure stabilization gas supply unit. Its lithium-rich liquid inlet is connected to the outlet of the cathode liquid preheating buffer tank through a pipeline. The carbonation reactor is equipped with a carbon dioxide inlet pipeline and a gas flow regulation device, a temperature monitoring and heating device, and a pH online monitoring module. The carbonation reactor outlet pipeline is connected to the second filtration unit. The liquid phase outlet of the second filtration unit is connected to the inlet of the membrane electrolysis cathode chamber through the second reflux pipeline, forming a closed-loop circulation loop of lithium precipitation mother liquor. The solid phase outlet produces battery-grade lithium carbonate and is transported to the feed end of the ball mill device.

[0072] The mixing and roasting unit includes a drying device, a closed ball milling device, and a high-temperature roasting furnace with controllable atmosphere. The ball milling device is equipped with a lithium carbonate inlet, a carbon source inlet, and a phosphorus source inlet for lithium iron phosphate regeneration. The delithiated solid phase output from the drying device enters the feeding end of the ball milling device. The closed ball milling device mixes the received delithiated solid phase, lithium carbonate, carbon source, and optional phosphorus source materials and then sends them to the high-temperature roasting furnace. The roasting furnace switches the atmosphere according to the type of raw materials (nitrogen / argon for lithium iron phosphate system, air / pure oxygen for ternary system). The roasting product is cooled, crushed, and sieved to obtain the finished regenerated cathode material.

[0073] The system's built-in parameter configuration module includes a cathode lithium concentration threshold setting unit, an oxidation precipitation reactor pH interlock control unit, a carbonation reactor temperature, gas flow, and pH adjustment unit, and a roasting atmosphere and temperature / time parameter configuration unit. It is equipped with a fully automated interlocking actuator: when the cathode lithium concentration does not reach the set threshold, the carbonation reactor feed valve is locked; when the pH of the oxidation precipitation reactor deviates from the 10-13 range, the cathode alkali feed flow rate is automatically adjusted; when the pH of the carbonation system exceeds the 9.5-11.5 range, the carbon dioxide gas supply flow rate regulation valve is activated; the roasting unit automatically matches the corresponding roasting temperature, holding time, and protective atmosphere according to the type of black powder raw material, achieving fully automated continuous closed-loop operation.

[0074] Comparative Example 1: Closed-loop regeneration of cathode black powder from retired lithium iron phosphate batteries (S3 pH adjustment and co-precipitation step omitted) The basic process is the same as in Example 1, except that in step S3, after the bromine oxidation delithiation reaction is completed, the lithium hydroxide alkaline solution produced in the cathode chamber is not introduced to adjust the pH of the system. Instead, the solid-liquid mixture in the oxidation precipitation reactor is directly discharged and filtered.

[0075] In Comparative Example 1, after omitting the pH adjustment co-precipitation step in step S3, the iron ions dissolved during the bromine oxidative delithiation process could not be retained in the solid phase but returned to the anode chamber with the lithium bromide-containing filtrate. As the cycle continued, iron ions accumulated in the anolyte, and hydroxides continuously deposited on the surface of the cation exchange membrane, clogging the membrane pores and preventing the device from operating normally.

[0076] In the S3 process of this invention, lithium hydroxide produced by the cathode is introduced to adjust the pH, so that the dissolved iron is simultaneously precipitated as hydroxide and retained in the solid phase. This can achieve efficient phase separation of lithium and iron in one solid-liquid separation, which not only avoids the accumulation of impurities in the lithium bromide circulating electrolyte and damage to the electrolyte membrane, and reduces electrolysis energy consumption, but also completely retains the iron source for subsequent regeneration of lithium iron phosphate. This verifies the advantages of in-situ precipitation and impurity removal and precise phase separation of lithium metal in this invention.

[0077] The embodiments of the present invention have been shown and described above. For those skilled in the art, improvements or modifications can be made based on the above description. For example, if the pretreated black powder contains aluminum as the anode current collector, it is treated with cathode alkaline solution to remove the aluminum; before oxidative lithium extraction, N-methylpyrrolidone or N,N-dimethylformamide is used to dissolve and extract the polyvinylidene fluoride binder in the black powder, or it can be removed directly by pyrolysis; after oxidative delithiation, the extraction slurry is separated into solid and liquid phases and then precipitated with cathode alkaline solution to dissolve the metal ions, and only the delithiated solid phase is used without adding alkali to precipitate the obtained solid phase and calcining it with lithium carbonate to prepare the cathode material; the filtrate returned to the anode chamber of the membrane electrolysis unit is deeply purified and then returned to the anode chamber to extend the service life of the membrane; during bromine oxidative delithiation, hydrobromic acid solution is used for acidification to accelerate the extraction rate and efficiency; the cathode tank is periodically cleaned with anode tank solution to dissolve lithium carbonate microcrystals on the membrane surface, or the cathode tank is periodically cleaned with hydrobromic acid solution, and after the lithium bromide in the solution reaches a certain concentration, it is used to replenish the anode tank solution, etc. All equivalent substitutions and process fine-tuning based on the fully closed-loop regeneration approach of “bromine oxidation delithiation at membrane electrolysis anode - lithium production and recycling at cathode - lithium carbonate precipitation - solid-phase roasting regeneration” fall within the protection scope of this invention.

Claims

1. A closed-loop green regeneration method for all components of retired lithium-ion batteries using lithium bromide-mediated electrochemical sorting, characterized in that, Includes the following steps: S1. Raw material pretreatment: After deep discharge, mechanical disassembly, crushing and sorting, and impurity removal, retired lithium-ion batteries are used to obtain pure positive electrode black powder. S2. Membrane electrolysis for bromine and lithium hydroxide production: A lithium bromide solution is prepared and fed into the anode chamber of a membrane-divided dual-chamber electrolyzer. A low-concentration lithium hydroxide solution is initially added to the cathode chamber as a supporting electrolyte. Bromine ions are electro-oxidized at the anode to generate a bromine-containing solution. An alkaline lithium hydroxide solution is generated in situ at the cathode. S3, bromine oxidation delithiation and precipitation removal: The bromine-containing solution at the anode is introduced into the oxidation precipitation reactor and mixed with the black powder at the cathode to react. The liquid bromine species oxidize the material lattice to achieve selective removal of lithium ions. After the bromine oxidation delithiation reaction is completed, a portion of the lithium hydroxide alkaline solution produced at the cathode is introduced to adjust the pH of the oxidation precipitation reactor system, so that the dissolved metal ions react with hydroxide ions to generate metal hydroxide precipitates. S4. Solid-liquid separation and filtrate recirculation: The solid-liquid mixture in the oxidation precipitation reactor is discharged as a whole and filtered to obtain a solid phase and a lithium bromide-containing filtrate; the lithium bromide-containing filtrate is returned to the anode chamber of step S2 as an electrolyte for recycling. S5. Carbonation precipitation of lithium and mother liquor reuse: The lithium ion concentration in the cathode chamber of step S2 is monitored in real time. When the lithium ion concentration reaches the set threshold, the lithium hydroxide alkaline solution of the cathode is taken out and preheated. Carbon dioxide gas is then introduced to carry out the carbonation reaction to generate lithium carbonate precipitate. After filtration, washing and drying, lithium carbonate product is obtained. The lithium precipitation mother liquor is returned to the cathode chamber of step S2 for recycling. S6. Closed-loop regeneration of cathode material: After drying the solid phase obtained in step S4, it is precisely mixed with the lithium carbonate obtained in step S5 according to the target cathode material stoichiometric ratio, and then calcined in a certain atmosphere. After cooling, crushing and sieving, the recycled cathode material is obtained, thus completing the closed-loop resource recycling of all components of the retired battery.

2. The method according to claim 1, characterized in that, In step S1, the retired lithium-ion battery is a lithium iron phosphate battery or a nickel-cobalt-manganese ternary lithium-ion battery.

3. The method according to claim 1, characterized in that, In step S2, the dual-chamber electrolytic cell is a corrosion-resistant electrolytic cell, and the membrane is selected from diaphragms used in caustic soda production or alkali-resistant cation exchange membranes; the anode is a shape-stable bromine-electrode electrode, and the cathode is selected from one of titanium electrode, stainless steel electrode, nickel electrode or graphite electrode.

4. The method according to claim 1, characterized in that, In step S2, the mass fraction of the lithium bromide solution is 1%~15%, and the mass fraction of the lithium hydroxide solution is 0.1%~5%; the membrane electrolysis voltage is 1.6~2.4 V, and the electrolysis is carried out at room temperature with stirring and cycling for 1~8 h; during the electrolysis process, the lithium ions dissolved from the positive electrode black powder migrate to the anode chamber with the anolyte, and migrate through the membrane to the cathode chamber under the drive of the electric field, where they combine with the hydroxide ions generated in situ at the cathode to continuously enrich lithium hydroxide.

5. The method according to claim 1, characterized in that, In step S3, the solid-liquid ratio of the positive electrode black powder to the bromine-containing solution in the oxidation precipitation reactor is 20~200 g / L; the pH of the oxidation precipitation reactor is controlled to 10~13, and the precipitation reaction time is 0.5~3 h.

6. The method according to claim 1, characterized in that, In step S4, the solid phase is a mixture of the delithiated cathode material and the metal hydroxide precipitate.

7. The method according to claim 1, characterized in that, In step S5, the set threshold for lithium ion concentration is ≥10 g / L, the preheating temperature is 70~95℃, and the pH of the reaction endpoint of the carbonation process is controlled to be 9.5~11.

5.

8. The method according to claim 1, characterized in that, In step S6, when the raw material is the positive electrode black powder of lithium iron phosphate battery, additional phosphorus and carbon sources are required. Lithium carbonate and solid phase are mixed at a Li:Fe molar ratio of 1.00~1.05:1, the amount of carbon source added is 5%~15% of the molar amount of iron, and phosphorus is added at a Fe:P molar ratio of 1:

1. The calcination temperature is 600~800℃, the calcination time is 2~8 h, and the calcination atmosphere is nitrogen or argon. When the raw material is the positive electrode black powder of ternary lithium-ion battery, additional carbon source is required. Lithium carbonate and solid phase are mixed at a Li / (Ni+Co+Mn) molar ratio of 1.02~1.08:1, and the amount of carbon source added is 3%~15% of the total molar amount of transition metal (Ni+Co+Mn). The material is reduced and calcined at 500~650℃ for 1~4 h in an inert atmosphere of nitrogen or argon, and then switched to an air or pure oxygen atmosphere and calcined at 800~950℃ for 3~10 h.

9. The method according to claim 8, characterized in that, In step S6, the carbon source is selected from at least one of glucose, sucrose, starch, citric acid, and acetylene black; the phosphorus source is selected from at least one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, and phosphoric acid.

10. A system for implementing the closed-loop green regeneration method for all components of retired lithium-ion batteries using lithium bromide-mediated electrochemical sorting as described in any one of claims 1 to 9, characterized in that, include: The membrane electrolysis unit includes an anode chamber and a cathode chamber of a dual-chamber electrolyzer. The anode chamber is equipped with an anolyte outlet and an anode filtrate return feed inlet. The cathode chamber is equipped with an online lithium-ion concentration monitoring module, a cathode liquid outlet, and an alkali distribution branch. The system is equipped with an interlock valve that opens only when the lithium-ion concentration in the cathode chamber is ≥ a set threshold. An oxidation precipitation reactor is provided, which is equipped with an online pH monitoring module and a stirring device. The oxidation precipitation reactor has an anolyte inlet, a positive electrode black powder feeding port, a discharge port, and an alkaline solution inlet. The anolyte inlet is connected to the anolyte outlet of the anode chamber through a pipeline; the alkaline solution inlet is connected to the alkaline solution distribution branch of the cathode chamber through a pipeline. The first filtration unit is provided with a solid-liquid mixture inlet, a solid phase outlet and a liquid phase outlet; the solid-liquid mixture inlet is connected to the outlet of the oxidation precipitation reactor through a pipeline, and the liquid phase outlet is connected to the anode filtrate return inlet through a first reflux pipeline, forming a closed-loop circulation circuit containing lithium bromide filtrate. The inlet of the cathode liquid preheating buffer tank is connected to the cathode liquid outlet of the cathode chamber via a pipeline; The carbonation reactor is equipped with a carbon dioxide pressure stabilizing gas supply unit. Its lithium-rich liquid inlet is connected to the outlet of the cathode liquid preheating buffer tank through a pipeline. The carbonation reactor is equipped with a carbon dioxide inlet pipeline and gas flow regulation device, temperature monitoring and heating device, pH online monitoring module, and the outlet of the carbonation reactor is connected to the second filtration unit. The second filtration unit has its inlet connected to the outlet of the carbonation reactor via a pipeline, and its liquid phase outlet connected to the cathode chamber inlet via a second reflux pipeline, forming a closed-loop circulation circuit for lithium precipitation mother liquor. The mixing and roasting unit includes a drying device, a ball milling device, and a high-temperature roasting furnace. The ball milling device is provided with a lithium carbonate inlet, a carbon source inlet, and a phosphorus source inlet for lithium iron phosphate regeneration. The inlet of the drying device is connected to the solid phase outlet of the first filtration unit, and the outlet of the drying device and the solid phase outlet of the second filtration unit are connected to the inlet of the ball milling device. The outlet of the ball milling device is connected to the inlet of the high-temperature roasting furnace. The system has a built-in parameter configuration module, including a cathode liquid lithium ion concentration setting threshold unit, an oxidation precipitation reactor pH control unit, a carbonation reactor pH, temperature, and aeration control unit, and a calcination atmosphere and temperature / time parameter configuration unit. All equipment is equipped with automatic interlocking actuators.

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