Recycling and regeneration method of waste battery electrode materials

Abstract

The present invention belongs to the field of recycling waste battery materials, and specifically discloses a method for recycling positive electrode materials in waste battery electrode materials. The method comprises the following steps: stripping the waste battery to obtain waste electrode materials containing waste positive electrode active materials; mixing the waste electrode materials with an auxiliary agent in a solid phase, filling the mixture, and sealing the mixture in a pressure-resistant container for heat treatment to obtain a heat-treated material; and subjecting the heat-treated material to water immersion treatment to obtain a water immersion liquid and a water immersion residue enriched with positive electrode active material cations. The auxiliary agent is a water immersion liquid having a chemical formula of FeA m ·Hydrated crystals of nH2O; A is Cl ‑ 、SO4 2‑ 、NO3 ‑ The waste electrode material comprises at least one anion, wherein the valence value of A*m=2, and n is an integer between 2 and 10; the weight ratio of the positive electrode active material to the auxiliary agent is 1:3-10; and the heat treatment temperature is between 100°C and 200°C. The process of the present invention can achieve excellent metal water leaching to recover lithium and can also regenerate high-performance materials.

Description

Technical Field

[0001] The present invention belongs to the field of battery waste recycling, and in particular relates to the field of waste lithium battery material recycling. Background Art

[0002] Lithium-ion batteries contain high concentrations of lithium, cobalt, nickel, manganese, iron, aluminum, copper, phosphorus and carbon. Recycling lithium mixed metal oxide batteries can save 51.3% of natural resources. Recycling lithium-ion batteries can not only avoid the release of heavy metals into the environment, but also recover and reuse valuable metals.

[0003] The main methods for recovering cathode materials from used lithium-ion batteries currently rely on full-element leaching, or pre-extracting lithium followed by leaching of other elements. For example, Chinese patent publication CN114956130A discloses a lithium pre-extraction process, specifically heating a mixed solution containing used lithium battery cathode powder, water, and a polyhydric alcohol until the water reaches a subcritical state. This subcritical state is maintained for lithium pre-extraction, followed by solid-liquid separation to obtain a lithium-extracted solution. The polyhydric alcohol preferably has a hydroxyl group count of greater than or equal to 2, and the volume fraction of the polyhydric alcohol in the water and polyhydric alcohol is greater than or equal to 30%. Another example, Chinese patent publication CN114752769A discloses a method for recovering valuable metals from used lithium battery materials using diaphragm pyrolysis. The stripped cathode powder is then acid-leached to produce a solution rich in lithium, nickel, cobalt, and manganese.

[0004] Although the full leaching effect of metals in the positive electrode has been continuously improved with the continuous evolution of technology, most of the existing full leaching processes need to be achieved by liquid phase leaching with acid solution, which consumes a lot of acid and produces a lot of three wastes. In addition, it is also easy to be accompanied by the leaching of Al current collector, which will increase the difficulty of subsequent impurity removal and recovery. Summary of the Invention

[0005] In response to the problems faced by the existing recycling of positive electrodes of waste lithium-ion batteries, the purpose of the present invention is to provide a method for recycling positive electrode materials in waste battery electrode materials, aiming to achieve full leaching recovery of positive electrode materials in waste battery materials based on all-solid-state heat treatment-water immersion.

[0006] The second purpose of the present invention is to provide a method for regenerating positive electrode materials in waste electrode materials, aiming to repair and regenerate waste positive electrode materials.

[0007] In the existing technology, most of the elements of the cathode material in the waste battery need to be fully leached by acid leaching. This method easily produces a lot of three wastes. In addition, it is easy to leach components such as the current collector, which increases the difficulty of subsequent element utilization. To address this problem, the present invention has been developed and provides the following new processing ideas and methods:

[0008] A method for recovering positive electrode materials from waste battery electrode materials comprises: stripping waste battery materials containing waste positive electrode active materials; mixing the waste electrode materials with an additive in a solid phase, filling and sealing the mixture in a pressure-resistant container, and performing heat treatment to obtain a heat-treated material; and subjecting the heat-treated material to water leaching to obtain a water leaching solution and water leaching residue enriched with positive electrode active material cations.

[0009] The auxiliary agent is a chemical formula of FeA m ·Hydrated crystals of nH2O; A is Cl - 、SO4 2- 、NO3 - At least one anion in, the valence value of A*m=2, and n is an integer of 2 to 10;

[0010] The weight ratio of the positive electrode active material to the auxiliary agent in the waste electrode material is 1:3-10;

[0011] The temperature of heat treatment is between 100°C and 200°C.

[0012] The present invention provides a method for achieving full leaching of positive electrode active material elements based on all-solid-state heat treatment-water immersion, which innovatively conducts solid-phase heat treatment on waste electrode materials and additives, based on the FeA in the additives. m The combined use of crystalline water and the controlled catalytic reduction and hydrolysis of spent cathode active materials facilitates valence modification and crystal structure disruption, leading to full water leaching. The process described in this invention achieves excellent full leaching efficiency and selectivity, avoids concomitant leaching of components such as the current collector, and reduces the production of waste acid and other waste products, resulting in excellent technical results.

[0013] In the present invention, there is no particular requirement for the type of the waste batteries. Considering the market value, they can be waste lithium-ion batteries.

[0014] In the present invention, there is no particular requirement for the type of waste positive electrode active material in the waste electrode material. For example, it may include at least one of conventional LiMO2 and LiNPO4, and the M is at least one of Ni, Co, and Mn, and the N is at least one of Fe and Mn.

[0015] In the present invention, the waste electrode materials may also contain at least one of waste graphite, silicon, and silicon-carbon composite materials as negative electrode active materials. The negative electrode active materials are enriched in the water-leaching residue after water-leaching treatment.

[0016] In the present invention, the waste electrode material is allowed to contain at least one of a conductive agent and a binder;

[0017] In the present invention, the waste electrode material is also permitted to contain a current collector. The present invention, based on the combined all-solid-state heat treatment and water leaching process, can achieve full water leaching of the elements in the positive electrode active material. Furthermore, this avoids the problem of simultaneous leaching of the current collector encountered in acid leaching, thereby improving the full leaching effect and selectivity of the positive electrode active material.

[0018] In the present invention, the use of the ferrous type crystallization auxiliary agent, combined with its dosage and heat treatment temperature, can improve the subsequent water leaching effect and selectivity.

[0019] In the present invention, n is 4-8.

[0020] Preferably, among the auxiliary agents, the auxiliary agents include auxiliary agent A and auxiliary agent B;

[0021] The auxiliary agent A is FeA a n1H2O, the A a SO4 2- , the n1 is 7;

[0022] The auxiliary agent B is FeA b 2·n2H2O, the A b Cl - , the n2 is 4.

[0023] The present invention studies have shown that the combination of the auxiliary agent A and the auxiliary agent B can unexpectedly further synergistically improve the treatment effect of the positive electrode active material, further improve the full water leaching rate and selectivity of the treated material, and help improve the electrochemical properties of the regenerated material.

[0024] In the present invention, among the auxiliary agents, the weight ratio of auxiliary agent A to auxiliary agent B is 1:0.1-10, further 1:0.5-1.5.

[0025] In the present invention, the weight ratio of the positive electrode active material to the auxiliary agent in the waste electrode material is 1:5-8;

[0026] In the present invention, the waste electrode material and the additive are mixed in solid phase, filled in a protective atmosphere and sealed in a pressure-resistant container; or after filling, the atmosphere in the pressure-resistant container is replaced by a protective atmosphere;

[0027] Preferably, the protective atmosphere is at least one of nitrogen and inert gas.

[0028] The present invention also shows that carrying out the filling in a protective atmosphere, or replacing the atmosphere in the pressure vessel with a protective atmosphere after filling, can unexpectedly improve the synergy of the process and help to further improve the water leaching effect and selectivity.

[0029] In the present invention, the heat treatment process is carried out at a relatively low temperature, so that it can be combined with the auxiliary agent to facilitate the subsequent water immersion effect.

[0030] Preferably, the heat treatment process includes two gradient insulation stages, wherein the temperature of the first insulation stage is 100-130°C and the temperature of the second insulation stage is 140-200°C. Further preferably, the temperature of the first insulation stage is 105-125°C and the temperature of the second insulation stage is 140-160°C.

[0031] The present invention studies show that carrying out the two-stage gradient treatment process in the presence of the auxiliary agent can further synergistically improve the subsequent water leaching effect and selectivity.

[0032] Preferably, the heat treatment time is 1 to 20 hours, preferably 4 to 10 hours.

[0033] In the present invention, when the heat treatment process is a two-stage gradient treatment process, the insulation time of the first insulation stage is 1 to 10 hours, and can further be 2 to 6 hours, and the insulation time of the second insulation stage is 1 to 5 hours, and can further be 2 to 4 hours.

[0034] In the present invention, thanks to the solid-state heat treatment assisted by the additive, water immersion can be achieved under relatively mild conditions.

[0035] For example, in the present invention, the solid-to-liquid ratio during the water immersion stage is 5 to 30 mL / g, preferably 10 to 20 mL / g. The temperature during the water immersion stage is 20 to 45°C. Furthermore, in a preferred embodiment of the present invention, excellent full water immersion can be achieved under even milder conditions, such as a liquid-to-solid ratio of 10 to 15 mL / g and a temperature of 20 to 30°C.

[0036] The time for the water immersion treatment is 0.1 h to 2 h, preferably 0.5 h to 1 h.

[0037] In the present invention, the leaching residue obtained by water leaching contains ferric oxide. When the treated waste electrode materials also contain negative electrode active materials, the waste active materials are also mainly enriched in the leaching residue.

[0038] The present invention also includes a method for regenerating waste battery electrode materials, which uses the recycling method of the present invention to obtain water-soaked residue and a water-soaked liquid enriched with positive electrode active material cations through water soaking treatment;

[0039] The aqueous solution is subjected to a deironing treatment and then to a coprecipitation treatment to separate the lithium solution and the metal slag of the treated positive electrode active material;

[0040] The metal slag and the lithium source are compositely oxidized and roasted to obtain a regenerated positive electrode active material.

[0041] The lithium source may be lithium hydroxide, lithium carbonate, etc. The oxidation roasting temperature may be 600-900° C., further 750-850° C. The oxidation roasting time may be 1-10 hours, further 4-8 hours.

[0042] In the present invention, the water extract can be subjected to iron removal treatment based on known processes, for example, the pH of the water extract is adjusted to 3-5, preferably 3.5-4.5, to precipitate iron, followed by solid-liquid separation to obtain an iron removal liquid, and then undergo subsequent co-precipitation treatment.

[0043] In the present invention, the regulator for regulating the water extract may be at least one of ammonia water, potassium hydroxide, and sodium hydroxide.

[0044] In the present invention, when the waste electrode materials also include waste negative electrode active materials, the water leaching treatment can produce water-leached residues enriched with negative electrode active materials, which can be regenerated to obtain regenerated negative electrode active materials using known processes, such as conventional carbon coating.

[0045] Beneficial effects

[0046] The present invention provides a method for achieving full leaching of positive electrode active material elements based on all-solid-state heat treatment-water immersion, which innovatively conducts solid-phase heat treatment on waste electrode materials and additives, based on the FeA in the additives. m The combined use of crystalline water and the controlled catalytic reduction and hydrolysis of spent cathode active materials facilitates valence modification and crystal structure disruption, leading to full water leaching. The process described in this invention achieves excellent full leaching efficiency and selectivity, avoids concomitant leaching of components such as the current collector, and reduces the production of waste acid and other waste products, resulting in excellent technical results.

[0047] In the present invention, the preferred combination of additives A and B, and / or filling under a protective atmosphere, and / or two-stage gradient heat treatment can unexpectedly further improve process synergy and further improve full water immersion efficiency and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The leaching results of Comparative Examples 2 to 4 are shown; DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below with reference to specific examples, but the present invention is not limited to the following examples.

[0050] In the present invention, the waste electrode material described in the present invention is an electrode material containing waste positive electrode active material, which can be waste positive electrode material or mixed black powder of waste positive electrode material and waste negative electrode material.

[0051] The present invention can cite the waste positive electrode treatment and regeneration method, which is to mix the solid raw materials containing the waste battery positive electrode material and the additives evenly, fill and seal them in a pressure-resistant reactor, and then place the reactor in an oven at 100-200 ° C to react for 1-20 hours. Then, the material is taken out and added with appropriate deionized water and stirred. After filtering, a leachate (water leachate) containing valuable metals in the positive electrode material and a water leach residue solid are obtained. The water leachate is selectively treated for iron removal and then co-precipitated under alkaline conditions to obtain a transition metal hydroxide precipitate. The lithium-rich solution is separated and sodium carbonate is added to obtain Li2CO3. The obtained transition metal hydroxide and lithium carbonate are oxidized and roasted in an oxygen atmosphere to obtain a regenerated ternary material.

[0052] In the present invention, there is no special requirement for the active material content in the waste electrode material. Considering the economic efficiency of the process, the content is preferably above 50 wt.%. In the following cases, unless otherwise stated, the active material content is 85-90 wt.%.

[0053] Example 1:

[0054] Step (1):

[0055] Waste battery power nickel cobalt manganese oxide lithium batteries (in this case, the initial NCM molar ratio is close to 1:1:1) are placed in 2 mol / L salt water for 30 hours of discharge treatment. The discharged batteries are dried at 85°C, disassembled and separated into positive and negative electrode sheets, and the positive electrode sheets are immersed in N-methylpyrrolidone to separate the current collectors in the electrode sheets. The waste positive electrode powder is filtered, washed with water, and dried;

[0056] Step (2):

[0057] A solid mixture of waste positive electrode powder and an additive (specifically additive A in this case, wherein the weight ratio of the positive electrode active material in the waste positive electrode powder to the additive A is 1:8) is loaded into a pressure-resistant reactor in an air atmosphere, and the volume of all solid materials in the reactor accounts for 50-55% by volume;

[0058] Step (3):

[0059] The reactor was sealed and heated to 150° C. (marked as T), and maintained at this temperature for 8 h for full solid-state heat treatment, followed by furnace cooling to obtain a heat-treated material.

[0060] The heat-treated material was mixed with deionized water and subjected to water immersion treatment, wherein the temperature of the water immersion stage was 40° C., the liquid-to-solid ratio was 20 ml / g, and the mixture was stirred and immersed in water for 60 minutes and then filtered to obtain a filtrate (water extract) and a filter residue.

[0061] In the filtrate, the leaching rates of various metal ions are Ni 98.7%, Co 98.9%, Mn 99.2%, and Li 99.7%.

[0062] Step (4):

[0063] Ammonia is added dropwise to the filtrate to adjust the pH of the system to 3.9-4.1, followed by solid-liquid separation to obtain an iron removal solution. Sodium hydroxide is then added to the iron removal solution to control the pH of the system to 10.9-11 for coprecipitation, followed by filtration to obtain a lithium-rich filtrate and NCM residue A. Sodium carbonate is added to the filtrate for lithium precipitation to obtain lithium carbonate residue B. NCM residue A and lithium carbonate residue B are dried, mixed in a certain proportion, and then calcined in an oxygen atmosphere for 6 hours (controlling the molar ratio of NCM to 1:1:1 and the molar ratio of Li:NCM to 1.05:1). They are then oxidatively calcined at 800°C (±10°C) for 6 hours to obtain a regenerated positive electrode active material.

[0064] Step (5):

[0065] The electrochemical performance of the regenerated positive electrode active material was tested under the following steps and conditions: in a glove box under argon atmosphere, aluminum foil was used as the current collector, a positive electrode sheet containing 90% regenerated positive electrode active material (regenerated positive electrode active material: conductive carbon black: PVDF weight ratio of 90:5:5) was coated, the negative electrode was a lithium sheet, 1 mol / L LiPF6 EC / EMC (volume ratio of 1:1) was used as the electrolyte, and the electrolyte showed 188 mAh g at room temperature and 1C constant current for 500 cycles. -1 cycle capacity.

[0066] Example 2:

[0067] Compared with Example 1, the only difference is that the auxiliary agent in step (2) is changed to auxiliary agent B, and the other operations and parameters are the same as Example 1.

[0068] In step (3), the leaching rate of each metal ion is Ni 98.6%, Co 98.8%, Mn 99.5%, and Li 99.8%.

[0069] At room temperature, the constant current cycle of 1C for 500 cycles showed a capacity of 185 mAh g -1 cycle capacity.

[0070] Example 3:

[0071] Compared to Example 1, the only difference is that the additives are additives A and B in a weight ratio of 1:1, and the total amount of additives is the same as in Example 1. Furthermore, in step 3, the water immersion temperature is 25°C, the liquid-to-solid ratio is 10 ml / g, and the leaching time is 30 minutes. Other operations and parameters are the same as in Example 1.

[0072] In the filtrate of step (3), the leaching rate of each metal ion is Ni 99.6%, Co 99.5%, Mn 99.8%, and Li 99.9%.

[0073] At room temperature, the constant current cycle of 1C for 500 cycles showed a capacity of 190 mAh g -1 cycle capacity.

[0074] The study showed that the combined use of additives A and B can unexpectedly achieve synergy, which can achieve better full water immersion effect of LNCM under milder conditions and help improve the electrochemical performance of the regenerated material.

[0075] Example 4

[0076] Compared with Example 1, the only difference is that, under the premise of keeping the amount of waste positive electrode powder unchanged, the ratio of positive electrode active material and auxiliary agent in the waste positive electrode powder is changed. The experimental groups are:

[0077] A: weight ratio of positive electrode active material / auxiliary agent A is 1:9;

[0078] B: weight ratio of positive electrode active material / auxiliary agent A 1:5;

[0079] The result is:

[0080] In the filtrate of step (3) in A, the leaching rate of each metal ion is Ni98.9%, Co99.1%, Mn99.6%, Li99.8%. At room temperature, 1C constant current cycle 500 cycles showed 189mAh g -1 cycle capacity.

[0081] In the filtrate of step (3) in B, the leaching rate of each metal ion was Ni98.1%, Co98.3%, Mn99.1%, and Li99.2%. At room temperature, the constant current cycle of 1C for 500 cycles showed 183 mAh g -1 cycle capacity.

[0082] Example 5:

[0083] Compared with Example 1, the only difference is that in step (3), the temperature T is 190° C. and the time is 5 h. Other operations and parameters are the same as in Example 1.

[0084] In the filtrate of step (3), the leaching rate of each metal ion is Ni 98.6%, Co 98.5%, Mn 99.1%, and Li 99.2%.

[0085] At room temperature, the constant current cycle of 1C for 500 cycles showed a capacity of 186 mAh g -1 cycle capacity.

[0086] Example 6

[0087] Compared with Example 1, the only difference is that after the filling is completed, the atmosphere of the system is replaced by Ar, and then subsequent treatment is carried out. In addition, in step 3, the water immersion temperature is 25°C, the liquid-solid ratio is 10 ml / g, and the leaching time is 30 min.

[0088] In the filtrate of step (3), the leaching rate of each metal ion is Ni 98.8%, Co 99.3%, Mn 99.3%, and Li 99.6%.

[0089] At room temperature, the constant current cycle of 1C for 500 cycles showed a capacity of 189 mAh g -1 cycle capacity.

[0090] As can be seen from Examples 1 and 6, solid-phase heat treatment in a preferred Ar atmosphere can unexpectedly further improve the thermal modification effect, and can achieve equivalent or even better water immersion full leaching effect under milder water immersion conditions.

[0091] Example 7

[0092] Compared with Example 1, the only difference is that in step (3), the heat treatment process includes a two-stage gradient treatment process, wherein the temperature of the first stage is 110°C for 5 hours, and then the temperature is increased to 150°C at a rate of 10°C / min and maintained for 3 hours. In addition, in step 3, the water immersion temperature is 25°C, the liquid-to-solid ratio is 10 ml / g, and the leaching time is 30 minutes.

[0093] In the filtrate of step (3), the leaching rate of each metal ion is Ni 99.7%, Co 99.5%, Mn 99.9%, and Li 99.9%.

[0094] At room temperature, the constant current cycle of 1C for 500 cycles showed a capacity of 193 mAh g -1 cycle capacity.

[0095] As can be seen from Examples 1 and 7, the solid-phase heat treatment proposed in the preferred two stages can unexpectedly further improve the thermal modification effect, and can also obtain equivalent or even better water immersion full leaching effect under milder water immersion conditions.

[0096] Comparative Example 1

[0097] Compared with Example 1, the only difference is that in step (2), an auxiliary agent A for removing crystallization water (that is, ferrous sulfate without crystallization water) is used as an auxiliary agent, and the total amount of the auxiliary agent remains unchanged. Other operations and parameters are the same as in Example 1.

[0098] In the filtrate of step (3), the leaching rate of each metal ion is Ni 43.7%, Co 42.5%, Mn 37.2%, and Li 63.4%.

[0099] Comparative Example 2

[0100] Compared with Example 1, the only difference is that in step (2), the auxiliary agent is replaced by an equal weight of CuSO4·5H2O, and the other operations and parameters are the same as those in Example 1.

[0101] In the filtrate of step (3), the leaching rate of each metal ion is Ni 23.1%, Co 22.5%, Mn 27.2%, and Li 45.9%.

[0102] Comparative Example 3

[0103] Compared with Example 1, the only difference is that in step (2), the auxiliary agent is replaced by an equal weight of ZnSO4·7H2O, and the other operations and parameters are the same as those in Example 1.

[0104] In the filtrate of step (3), the leaching rate of each metal ion is Ni 25.9%, Co 29.5%, Mn 38.9%, and Li 50.3%.

[0105] Comparative Example 4

[0106] Compared with Example 1, the only difference is that in step (2), the auxiliary agent is replaced by an equal weight of MgSO4·7H2O, and the other operations and parameters are the same as those in Example 1.

[0107] In the filtrate of step (3), the leaching rate of each metal ion is Ni31.8%, Co34.8%, Mn36.2%, and Li53.4%.

[0108] Comparative Example 5:

[0109] Compared with Example 1, the only difference is that no auxiliary agent with crystallization water is used. Instead, in step (2), ferrous sulfate without crystallization water and deionized water are added so that the molar ratio of ferrous sulfate to water is 1:7. Other operations and parameters are the same as those in Example 1.

[0110] In the filtrate of step (3), the leaching rate of each metal ion is Ni89.5%, Co85.7%, Mn91.9%, and Li93.4%.

[0111] Comparative Example 6

[0112] Compared with Example 1, the only difference is that in step (3), the temperature T is set to 80° C., and other operations and parameters are the same as in Example 1.

[0113] In the filtrate of step (3), the leaching rate of each metal ion is Ni 63.4%, Co 60.7%, Mn 42.9%, and Li 80.1%.

Claims

1. A method for recovering positive electrode materials from waste battery electrode materials, characterized in that: Stripping waste electrode materials containing waste positive electrode active materials from waste batteries; mixing the waste electrode materials with an additive in a solid phase, filling and sealing the mixture in a pressure-resistant container, and performing heat treatment to obtain a heat-treated material; and subjecting the heat-treated material to water leaching to obtain a water leaching solution and a water leaching residue enriched with positive electrode active material cations. The auxiliary agent is a chemical formula of FeA m ·Hydrated crystals of nH2O; where A is Cl - 、SO4 2- 、NO3 - At least one anion in the formula (A), the valence value of A*m=2, and n is an integer from 2 to 10; The weight ratio of the positive electrode active material to the auxiliary agent in the waste electrode material is 1:3-10; The heat treatment temperature is between 100℃ and 200℃; The waste batteries are waste lithium-ion batteries; The waste positive electrode active material includes at least one of LiMO2 and LiNPO4, wherein M is at least one of Ni, Co, and Mn, and N is at least one of Fe and Mn; The waste electrode material and the auxiliary agent are mixed in solid phase, filled in a protective atmosphere and sealed in a pressure-resistant container; or the atmosphere in the pressure-resistant container is replaced by the protective atmosphere after filling.

2. The recycling method according to claim 1, wherein The waste electrode materials also contain at least one negative electrode active material selected from waste graphite, silicon, and silicon-carbon composite materials.

3. The recycling method according to claim 1, wherein: The waste electrode material also contains at least one of a conductive agent and a binder.

4. The recycling method according to claim 1, wherein The waste electrode material also contains a current collector.

5. The recycling method according to claim 1, wherein: Among the auxiliary agents, the auxiliary agents include auxiliary agent A and auxiliary agent B; The auxiliary agent A is FeA a n1H2O, the A a SO4 2- , the n1 is 7; The auxiliary agent B is FeA b 2·n2H2O, the A b Cl - , the n2 is 4.

6. The recycling method according to claim 5, wherein: Among the auxiliary agents, the weight ratio of auxiliary agent A to auxiliary agent B is 1:0.1-10.

7. The recycling method according to claim 1, wherein: The protective atmosphere is at least one of nitrogen and inert gas.

8. The recycling method according to claim 1, wherein: The heat treatment process includes two gradient insulation stages, wherein the temperature of the first insulation stage is 100~130℃; the temperature of the second insulation stage is 140~200℃.

9. The recycling method according to claim 8, wherein: The temperature of the first insulation stage is 105~125℃; the temperature of the second insulation stage is 140~160℃.

10. The recycling method according to claim 8, wherein: The holding time of the first holding stage is 1 to 10 hours, and the holding time of the second holding stage is 1 to 5 hours.

11. The recycling method according to claim 1, wherein: The solid-liquid ratio in the water immersion stage is 5~30 mL / g.

12. The recycling method according to claim 1, wherein: The temperature during the water immersion treatment stage is 20~45℃.

13. The recycling method according to claim 1, wherein: The time of water immersion treatment is 0.1h~2h.

14. The recycling method according to claim 1, wherein: The water immersion treatment time is 0.5~1h.

15. A method for regenerating waste battery electrode materials, characterized in that: The recovery method according to any one of claims 1 to 14 is used to obtain water-soaked residue and a water-soaked liquid enriched with cations of the positive electrode active material through water-soaking treatment; The aqueous solution is subjected to a deironing treatment and then to a coprecipitation treatment to separate the lithium solution and the metal slag of the treated positive electrode active material; The metal slag and the lithium source are compositely oxidized and roasted to obtain a regenerated positive electrode active material.

16. The method for regenerating waste battery electrode materials according to claim 15, characterized in that: The pH of the water extract is adjusted to 3-5 to precipitate the iron, and then the solid-liquid separation is carried out to obtain the iron removal liquid, which is then subjected to subsequent co-precipitation treatment.

17. The method for regenerating waste battery electrode materials according to claim 16, wherein: The water-leached residue contains negative electrode active material, which is regenerated to obtain regenerated negative electrode active material.

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