Method for recycling metal of waste lithium battery by using carbon dioxide

Abstract

The invention discloses a method for recycling metal of a waste lithium battery by using carbon dioxide, which comprises the following steps: (1) discharging, disassembling and crushing a retired lithium nickel cobalt manganate ternary lithium ion battery to obtain a positive pole piece, and separating a positive active material from the pole piece to obtain a lithium nickel cobalt manganate positive material; (2) soaking the nickel cobalt lithium manganate positive electrode material in the mixed solution of oxalic acid, citric acid and L-ascorbic acid, heating in a water bath to 90 + / -3 DEG C for leaching, adding a small amount of ferrous chloride, and collecting the leachate; and (3) introducing excessive carbon dioxide gas into the leach liquor at the constant temperature of 5-8 DEG C ice bath, removing a precipitated phase, heating to separate out a solid phase, carrying out alcohol precipitation, filtering, and drying to obtain a lithium carbonate recovery product. Lithium carbonate recovered through the method has the high leaching rate, it can be guaranteed that lithium is recovered to the maximum extent, and the technological method is simple and convenient to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling of lithium battery cathode materials, and particularly to a method for recycling metals from waste lithium batteries by using carbon dioxide. Background Art

[0002] Lithium batteries are constantly undergoing rapid changes. Lithium batteries have become a dazzling star in chemical energy due to their excellent performance. With the continuous improvement of scientists' requirements for high-capacity and high-energy-density and further development, lithium batteries will inevitably play a crucial role in the future energy structure. With the rapid development of lithium batteries, the problem of recycling waste battery materials has become increasingly prominent. According to relevant literature, by 2035, the global waste lithium batteries will reach more than 6 million tons. If not properly treated and recycled, it will not only waste resources but also pollute the environment. Therefore, the recycling and resource utilization of waste lithium battery materials are particularly important. Lithium batteries are classified according to the cathode materials, including lithium cobalt oxide batteries, lithium manganese oxide batteries, lithium iron phosphate batteries, nickel cobalt manganese ternary material batteries, etc. Among them, ternary materials are widely used as the cathode materials of lithium batteries in fields such as electric vehicles or portable tools due to their advantages such as high energy density and good cycle life. The recycling methods include wet method, pyrometallurgy, etc. At present, mainly through hydrometallurgy to recycle waste lithium ion batteries, but there are still problems in the recycling process such as complex and cumbersome processes, difficult separation of metal recycling, and treatment of "three wastes". Therefore, it is necessary to continuously explore and improve the recycling process and find more suitable recycling methods to meet the needs of the growing waste lithium ion battery recycling market. Summary of the Invention

[0003] For this reason, the present invention provides a method for recycling metals from waste lithium batteries by using carbon dioxide. The steps include:

[0004] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the cathode plate containing lithium nickel cobalt manganese oxide. Immerse the cathode plate in triethyl phosphate for 30 - 40 minutes to separate the cathode active material from the plate, perform solid-liquid separation, wash the solid phase, and dry it to obtain the lithium nickel cobalt manganese oxide cathode material;

[0005] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. Immerse the lithium nickel cobalt manganese oxide cathode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, heat it in a water bath to 90 ± 3 °C, and stir it at a constant temperature of 90 ± 3 °C for 30 - 40 min. During the constant temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride, and continue to stir at a constant temperature of 90 ± 3 °C for 10 - 20 min after the addition is completed. Then cool it naturally to room temperature, perform solid-liquid separation to remove the leaching residue, and collect the leachate;

[0006] (3) Mix the waste gas collected from the previous process and carbon dioxide gas, and introduce it into the leachate maintained at a constant temperature of 5 - 8 °C in an ice bath to ensure an excess of carbon dioxide gas. Then perform solid-liquid separation to remove the precipitate phase, heat the liquid phase to 80 - 90 °C to precipitate the solid phase, perform alcohol precipitation, filter, and dry the solid phase at 100 °C for more than 1 h to obtain the lithium carbonate recovery product.

[0007] Further, in the step (1), the mass ratio of the positive electrode plate immersed in triethyl phosphate is positive electrode plate:triethyl phosphate = 1:50 - 100.

[0008] Further, in the step (2), in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 80 - 90 g / L, the concentration of citric acid is 60 - 65 g / L, the concentration of L-ascorbic acid is 30 - 35 g / L, and the solvent is water.

[0009] Further, in the step (2), the amount ratio of the lithium nickel cobalt manganese oxide cathode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide cathode material:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 20 - 30 g:1 L.

[0010] Further, in the step (2), the addition amount ratio of ferrous chloride to the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is ferrous chloride:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 1 - 4 g:1 L.

[0011] The beneficial effects of the present invention are as follows: The lithium carbonate recovered by the method of the present invention has a high leaching rate, can ensure the maximum recovery of lithium, and the process method is simple and easy to operate. Description of the Drawings

[0012] Figure 1 It is a comparison chart of the lithium leaching rates of the methods described in each example and comparative example. Detailed Embodiments

[0013] The mechanism of the present invention lies in: acid leaching the lithium nickel cobalt manganese oxide cathode material through the acidic and reducing environment of the mixture of oxalic acid, citric acid and L-ascorbic acid, where oxalic acid and L-ascorbic acid are used as composite reducing agents, and at the same time oxalic acid and citric acid provide an acidic environment. The main reaction formula is:

[0014] LiNi x Co y Mn z O2 + H2C2O4 (oxalic acid) + C6H8O6 (L-ascorbic acid) + H + →Li + + Ni 2+ + Co 2+ + Mn 2+ + CO2↑ + H2O; Adding ferrous ions is beneficial to catalyze the decomposition of oxalic acid to generate highly reactive free radicals (·CO2 - ), significantly improving the reduction ability and making the leaching rate higher and more complete:

[0015] H2C2O4 + Fe 2+ →Fe 3+ + 2CO2 + 2H + + 2e - ;

[0016] Fe 3+ + H2C2O4 → Fe 2+ + ·CO2 - + H + ;

[0017] Among them, the insoluble substances in the leaching process are filtered out, and the large amount of carbon dioxide generated is used later.

[0018] In the above leaching solution, through excessive carbon dioxide, Ni 2+ 、Co 2+ 、Mn 2+ ions form carbonate precipitates, and lithium carbonate continues to react with carbon dioxide to form soluble lithium bicarbonate. The insoluble substances are filtered out to achieve the separation of lithium:

[0019] Li2CO3 + CO2 + H2O → 2LiHCO3;

[0020] Since lithium bicarbonate is easily decomposed by heat, the reaction is required to be carried out in an ice bath constant temperature environment. The solution containing lithium bicarbonate is then heated to about 85°C to promote the decomposition of lithium bicarbonate into lithium carbonate precipitate, and the final lithium-containing product is obtained.

[0021] The following further illustrates the present invention with reference to embodiments.

[0022] Example 1

[0023] A method for recycling metals from waste lithium batteries using carbon dioxide, the steps including:

[0024] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the positive electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the positive electrode sheet in triethyl phosphate for 30 - 40 min to separate the positive electrode active material from the electrode sheet. In step (1), the mass ratio of the positive electrode sheet immersed in triethyl phosphate is positive electrode sheet:triethyl phosphate = 1:50; perform solid-liquid separation, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide positive electrode material;

[0025] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. In the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 80 g / L, the concentration of citric acid is 60 g / L, and the concentration of L-ascorbic acid is 30 g / L, and the solvent is water; immerse the lithium nickel cobalt manganese oxide positive electrode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid. The dosage ratio of the lithium nickel cobalt manganese oxide positive electrode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide positive electrode material:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 20 g:1 L; heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 30 min. During the constant-temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring ends, add a small amount of ferrous chloride. The addition amount of ferrous chloride and the amount ratio of the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is ferrous chloride:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 1 g:1 L; continue to stir at a constant temperature of 90 °C for 10 min after the feeding is completed, then naturally cool to room temperature, perform solid-liquid separation to remove the leaching residue, and collect the leaching solution;

[0026] (3) Mix the waste gas collected from the previous process and carbon dioxide gas and introduce them into the leaching solution maintained at a constant temperature of 5 °C in an ice bath, ensure that the carbon dioxide gas is in excess, then perform solid-liquid separation to remove the precipitate phase, heat the liquid phase to 85 °C to precipitate the solid phase, then add ethanol for alcohol precipitation, filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0027] Example 2

[0028] A method for recycling metals from waste lithium batteries using carbon dioxide, the steps including:

[0029] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the positive electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the positive electrode sheet in triethyl phosphate for 30 min to separate the positive electrode active material from the sheet. In step (1), the mass ratio of the positive electrode sheet immersed in triethyl phosphate is positive electrode sheet:triethyl phosphate = 1:50; perform solid-liquid separation, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide positive electrode material;

[0030] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. In the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 85 g / L, the concentration of citric acid is 60 g / L, and the concentration of L-ascorbic acid is 30 g / L, and the solvent is water; immerse the lithium nickel cobalt manganese oxide positive electrode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid. The amount ratio of the lithium nickel cobalt manganese oxide positive electrode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide positive electrode material:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 25 g:1 L; heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 30 min. During the constant temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride. The addition amount of ferrous chloride and the amount ratio of the mixed solution of oxalic acid, citric acid, and L-ascorbic acid are ferrous chloride:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 2 g:1 L; continue to stir at a constant temperature of 90 °C for 10 min after the feeding is completed, and then naturally cool to room temperature. Perform solid-liquid separation to remove the leaching residue and collect the leaching solution;

[0031] (3) Mix the waste gas collected from the previous process and carbon dioxide gas and introduce them into the leaching solution maintained at a constant temperature of 5 °C in an ice bath to ensure an excess of carbon dioxide gas. Then perform solid-liquid separation to remove the precipitate phase. Heat the liquid phase to 85 °C to precipitate the solid phase and then add ethanol for alcohol precipitation. Filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0032] Example 3

[0033] A method for recovering metals from waste lithium batteries using carbon dioxide, the steps include:

[0034] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the positive electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the positive electrode sheet in triethyl phosphate for 30 min to separate the positive electrode active material from the sheet. In step (1), the mass ratio of the positive electrode sheet immersed in triethyl phosphate is positive electrode sheet:triethyl phosphate = 1:50; perform solid-liquid separation, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide positive electrode material;

[0035] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. In the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 85 g / L, the concentration of citric acid is 65 g / L, and the concentration of L-ascorbic acid is 35 g / L. The solvent is water. Immerse the lithium nickel cobalt manganese oxide cathode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid. The mass ratio of the lithium nickel cobalt manganese oxide cathode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide cathode material: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 25 g: 1 L. Heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 30 min. During the constant-temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride. The addition amount of ferrous chloride and the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is ferrous chloride: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 3 g: 1 L. After the feeding is completed, continue to stir at a constant temperature of 90 °C for 10 min, then naturally cool to room temperature, separate the solid and liquid to remove the leaching residue, and collect the leaching solution.

[0036] (3) Mix the waste gas collected from the previous process and carbon dioxide gas and introduce them into the leaching solution kept at a constant temperature of 5 °C in an ice bath to ensure an excess of carbon dioxide gas. Then, separate the solid and liquid to remove the precipitate phase. Heat the liquid phase to 85 °C to precipitate the solid phase, add ethanol for alcohol precipitation, filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0037] Example 4

[0038] A method for recycling metals from waste lithium batteries using carbon dioxide, the steps include:

[0039] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain a cathode plate containing lithium nickel cobalt manganese oxide. Immerse the cathode plate in triethyl phosphate for 30 min to separate the cathode active material from the plate. In step (1), the mass ratio of the cathode plate immersed in triethyl phosphate is cathode plate: triethyl phosphate = 1:50. Separate the solid and liquid, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide cathode material.

[0040] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. In the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 90 g / L, the concentration of citric acid is 65 g / L, and the concentration of L-ascorbic acid is 35 g / L. The solvent is water. Immerse the lithium nickel cobalt manganese oxide cathode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid. The mass ratio of the lithium nickel cobalt manganese oxide cathode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide cathode material: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 30 g: 1 L. Heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 30 min. During the constant-temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride. The addition amount of ferrous chloride and the amount of the mixed solution of oxalic acid, citric acid, and L-ascorbic acid are in the ratio of ferrous chloride: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 4 g: 1 L. After the feeding is completed, continue to stir at a constant temperature of 90 °C for 10 min, then naturally cool to room temperature, perform solid-liquid separation to remove the leaching residue, and collect the leaching solution.

[0041] (3) Mix the waste gas collected from the previous process and carbon dioxide gas, and then introduce them into the leaching solution maintained at a constant temperature of 5 °C in an ice bath to ensure an excess of carbon dioxide gas. Then perform solid-liquid separation to remove the precipitate phase. Heat the liquid phase to 85 °C to precipitate the solid phase, then add ethanol for alcohol precipitation, filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0042] Comparative Example 1

[0043] A method for recycling metals from waste lithium batteries for comparison, the steps include:

[0044] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain a positive electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the positive electrode sheet in triethyl phosphate for 30 min to separate the positive electrode active material from the electrode sheet. In step (1), the mass ratio of the positive electrode sheet immersed in triethyl phosphate is positive electrode sheet: triethyl phosphate = 1:50. Perform solid-liquid separation, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide cathode material.

[0045] (2) Prepare a mixed solution of oxalic acid and citric acid. In the mixed solution of oxalic acid and citric acid, the concentration of oxalic acid is 85 g / L, the concentration of citric acid is 65 g / L, and the solvent is water. Immerse the lithium nickel cobalt manganese oxide cathode material in the mixed solution of oxalic acid and citric acid. The mass ratio of the lithium nickel cobalt manganese oxide cathode material immersed in the mixed solution of oxalic acid and citric acid is lithium nickel cobalt manganese oxide cathode material: mixed solution of oxalic acid and citric acid = 25 g: 1 L. Heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 30 min. During the constant temperature stirring process, extract the exhaust gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride. The addition amount of ferrous chloride and the amount ratio of the mixed solution of oxalic acid, citric acid, and L-ascorbic acid are ferrous chloride: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 3 g: 1 L. After the feeding is completed, continue to stir at a constant temperature of 90 °C for 10 min, then naturally cool to room temperature, separate the solid and liquid to remove the leaching residue, and collect the leaching solution.

[0046] (3) Mix the exhaust gas collected from the previous process and carbon dioxide gas and introduce them into the leaching solution kept at a constant temperature of 5 °C in an ice bath to ensure that the carbon dioxide gas is in excess. Then separate the solid and liquid to remove the precipitate phase. Heat the liquid phase to 85 °C to precipitate the solid phase, then add ethanol for alcohol precipitation, filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0047] Comparative Example 2

[0048] A method for recycling metals from waste lithium batteries for comparison, the steps include:

[0049] (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the cathode electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the cathode electrode sheet in triethyl phosphate for 30 min to separate the cathode active material from the electrode sheet. In step (1), the mass ratio of the cathode electrode sheet immersed in triethyl phosphate is cathode electrode sheet: triethyl phosphate = 1:50. Separate the solid and liquid, wash the solid phase with deionized water 3 times, and dry it to obtain the lithium nickel cobalt manganese oxide cathode material.

[0050] (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. In the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 85 g / L, the concentration of citric acid is 65 g / L, and the concentration of L-ascorbic acid is 35 g / L. The solvent is water. Immerse the lithium nickel cobalt manganese oxide cathode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid. The mass ratio of the lithium nickel cobalt manganese oxide cathode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide cathode material: mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 25 g: 1 L. Heat in a water bath to 90 °C and stir at a constant temperature of 90 °C for 40 min. During the constant temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process, then cool naturally to room temperature, perform solid-liquid separation to remove the leaching residue, and collect the leaching solution.

[0051] (3) Mix the waste gas collected from the previous process and carbon dioxide gas, and then introduce them into the leaching solution kept at a constant temperature of 5 °C in an ice bath to ensure an excess of carbon dioxide gas. Then perform solid-liquid separation to remove the precipitate phase. Heat the liquid phase to 85 °C to precipitate the solid phase, add ethanol for alcohol precipitation, filter, and dry the solid phase at 100 °C for 1 h to obtain the lithium carbonate recovery product.

[0052] Use an atomic absorption spectrophotometer to measure the component content of the lithium carbonate recovery product obtained by the methods of the above examples and comparative examples respectively, and calculate the leaching rate of lithium. The results are as Figure 1 shown. It can be seen from the figure that the lithium carbonate recovered by the method of the present invention has a high leaching rate, which can ensure the maximum recovery of lithium, and the process method is simple and easy to operate. Comparing Example 3 with each comparative example, it can be seen that adding oxalic acid alone or not adding ferrous salt will significantly affect the leaching rate of lithium.

[0053] The technical solutions provided by the present invention have been introduced in detail above. For those of ordinary skill in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for recycling metal from waste lithium batteries using carbon dioxide, characterized in that the steps Including: (1) Discharge the retired lithium nickel cobalt manganese oxide ternary lithium-ion battery, then disassemble and crush it in a nitrogen atmosphere to obtain the positive electrode sheet containing lithium nickel cobalt manganese oxide. Immerse the positive electrode sheet in triethyl phosphate for 30 - 40 min to separate the positive electrode active material from the electrode sheet, perform solid-liquid separation, wash the solid phase, and dry it to obtain the lithium nickel cobalt manganese oxide positive electrode material; (2) Prepare a mixed solution of oxalic acid, citric acid, and L-ascorbic acid. Immerse the lithium nickel cobalt manganese oxide positive electrode material in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, heat it in a water bath to 90 ± 3°C, and stir it at a constant temperature of 90 ± 3°C for 30 - 40 min. During the constant temperature stirring process, extract the waste gas generated by the reaction and introduce it into the next process. After the stirring is completed, add a small amount of ferrous chloride. After the feeding is completed, continue to stir at a constant temperature of 90 ± 3°C for 10 - 20 min, and then naturally cool it to room temperature. Perform solid-liquid separation to remove the leaching residue and collect the leaching solution; (3) Mix the waste gas collected in the previous process with carbon dioxide gas and introduce it into the leaching solution maintained at a constant temperature of 5 - 8°C in an ice bath to ensure an excess of carbon dioxide gas. Then perform solid-liquid separation to remove the precipitation phase, heat the liquid phase to 80 - 90°C to precipitate the solid phase, perform alcohol precipitation, filter, and dry the solid phase at 100°C for more than 1 h to obtain the lithium carbonate recovery product.

2. The method for recycling metal from waste lithium batteries using carbon dioxide according to claim 1, wherein In the step (1), the mass ratio of the positive electrode sheet immersed in triethyl phosphate is positive electrode sheet:triethyl phosphate = 1:50 - 100.

3. The method for recycling metal from waste lithium batteries using carbon dioxide according to claim 1, wherein In the step (2), in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid, the concentration of oxalic acid is 80 - 90 g / L, the concentration of citric acid is 60 - 65 g / L, the concentration of L-ascorbic acid is 30 - 35 g / L, and the solvent is water.

4. A method for recycling metal from waste lithium batteries using carbon dioxide according to claim 1, characterized in that, In the step (2), the dosage ratio of the lithium nickel cobalt manganese oxide positive electrode material immersed in the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is lithium nickel cobalt manganese oxide positive electrode material:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 20 - 30 g:1 L.

5. A method for recycling metal from waste lithium batteries using carbon dioxide according to claim 1, characterized in that, In the step (2), the dosage ratio of the added ferrous chloride to the mixed solution of oxalic acid, citric acid, and L-ascorbic acid is ferrous chloride:mixed solution of oxalic acid, citric acid, and L-ascorbic acid = 1 - 4 g:1 L.

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