Method for preparing high-voltage lithium cobalt oxide cathode material by modifying and recycling normal-pressure waste lithium cobalt oxide battery

Abstract

The application discloses a method for preparing high-pressure lithium cobalt oxide cathode material by modifying and recycling normal-pressure waste lithium cobalt oxide battery, and relates to the technical field of lithium ion battery resource recycling. The method uses waste lithium cobalt oxide battery powder as raw material, adds lithium source and magnesium source according to the stoichiometric ratio based on the residual aluminum content, uniformly mixes to obtain a mixture, and performs sintering treatment on the mixture in an oxygen-containing atmosphere to obtain regenerated high-pressure lithium cobalt oxide cathode material. The application uses waste LCO as raw material, through controllable heat treatment under normal pressure and other processes, uses inherent residual aluminum in the material as a structure stabilizing unit, only introduces the minimum amount of exogenous modification elements, promotes the residual aluminum and the exogenous elements to occur in synergistic doping and interface reconstruction, thereby in-situ constructing a high-pressure stable interface phase and bulk phase doping structure on the surface and near-surface area of the material. The method directly realizes the performance upgrading of the waste LCO material to the high-pressure state, and significantly improves the cycle stability and reversible capacity of the regenerated material under high pressure.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery resource recycling technology, specifically to a method for modifying and regenerating waste lithium cobalt oxide batteries under normal pressure to prepare high-voltage lithium cobalt oxide cathode materials. Background Technology

[0002] Lithium cobalt oxide (LCO) cathode materials recovered from consumer electronics typically undergo aluminum doping modification in their precursors to improve cycle performance, resulting in the presence of bulk aluminum in the failed materials. Current research on the regeneration of waste LCO mainly focuses on lithium replenishment to restore capacity or treating it as a "blank matrix" for re-doping / coating. These methods fail to fully utilize the beneficial residual elements (such as aluminum) in the waste materials as a structural basis for regeneration, leading to resource waste and failing to leverage the potential synergistic effects of residual aluminum and introduced elements. This results in complex regeneration processes and limited performance improvements. In particular, no effective solution has yet been found for utilizing these "legacy" elements to upgrade materials to higher performance and high-voltage states (>4.5V) with minimal external addition. Summary of the Invention

[0003] This invention aims to overcome the shortcomings of existing recycling technologies that neglect the inherent characteristics of raw materials, and provides a method for modifying and regenerating waste lithium cobalt oxide (LCO) batteries under ambient pressure to prepare high-voltage LCO cathode materials. The core of this invention lies in: identifying and utilizing the inherent residual aluminum in waste LCO as a structurally stable foundation; and through the precise introduction of magnesium and lithium sources, achieving a synergistic doping effect between residual Al and newly introduced Mg in a one-step heat treatment process, thereby directly upgrading and regenerating waste LCO into a stable cathode material suitable for 4.6V high-voltage cycling.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing high-voltage lithium cobalt oxide cathode materials by modifying and regenerating spent lithium cobalt oxide batteries under normal pressure includes the following steps:

[0006] 1) Using waste lithium cobalt oxide battery powder as raw material, determine its residual aluminum content and, based on this, add lithium source and magnesium source according to stoichiometric ratio, and mix evenly to obtain a mixture.

[0007] 2) The mixture is sintered once in an oxygen-containing atmosphere at a temperature of 750-950℃ for 10-20 h. After cooling, the recycled high-voltage lithium cobalt oxide cathode material is obtained.

[0008] Furthermore, the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate, or lithium acetate, and the amount of lithium source added is 3%-10% more than the amount of lithium missing in the waste lithium cobalt oxide battery powder.

[0009] Furthermore, the magnesium source is at least one of magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium nitrate, or magnesium citrate, and the amount of magnesium source added satisfies the molar ratio of magnesium to residual aluminum in the mixture being 1:0.2-1:5.

[0010] Furthermore, the mixing in step 1) is carried out by mechanical chemical ball milling for 2-8 hours; the sintering temperature in step 2) is 850℃-900℃.

[0011] Further, the oxygen-containing atmosphere mentioned in step 2) is oxygen or air, and the airflow pressure is atmospheric pressure.

[0012] The regenerated high-voltage lithium cobalt oxide cathode material of the present invention, under the condition of a cutoff voltage of 4.5V and a charge-discharge cycle test at a 1C rate, has a capacity retention rate of not less than 85% after 400 cycles.

[0013] The regenerated high-voltage lithium cobalt oxide cathode material of the present invention shows an α-NaFeO2 type layered structure in the X-ray diffraction pattern, and the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak I(003) / I(104) is greater than 1.2.

[0014] The present invention also provides a lithium-ion battery cathode sheet comprising the aforementioned regenerated high-voltage lithium cobalt oxide cathode material.

[0015] The present invention also provides a lithium-ion battery comprising the aforementioned lithium-ion battery positive electrode.

[0016] The method of this invention promotes the synergistic effect of externally added magnesium ions and the inherent residual aluminum ions in the bulk phase of the material through a heat treatment process, so that they jointly enter the lithium cobalt oxide lattice and form a stable Al / Mg co-doped crystal structure.

[0017] This invention adopts the above technical solution to address the problems of existing waste lithium cobalt oxide regeneration technologies failing to fully utilize residual aluminum elements, having complex regeneration processes, and being difficult to upgrade high-pressure performance. It uses dismantled and recycled waste LCO as raw material and employs processes such as controllable heat treatment under normal pressure to utilize the inherent residual aluminum in the material as a structural stabilizing unit. Only a minimum amount of exogenous modifying elements are introduced to promote synergistic doping and interface reconstruction between residual aluminum and exogenous elements, thereby constructing a stable interface phase and bulk phase doped structure under high pressure in situ on the material surface and near-surface region.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. By using the often-overlooked residual aluminum in waste materials of lithium cobalt oxide batteries as an "in-situ dopant", the use of external dopant is reduced, the raw material cost is lowered, and the valuable components in the waste materials are maximized and intelligently utilized.

[0020] 2. Residual Al and newly introduced Mg exhibit a synergistic doping effect during high-temperature regeneration. The strong bond energy of Al³⁺ helps stabilize the crystal lattice framework and suppress oxygen evolution; the introduction of Mg²⁺ can modulate the crystal field environment, improve lithium-ion mobility, and further suppress phase transitions. The synergistic effect of these two dopants enhances the bulk structural stability of the material under high pressure from different dimensions, with better results than single doping.

[0021] 3. This invention perfectly integrates "lithium replenishment repair" and "Al / Mg synergistic high-pressure modification" into a single heat treatment step, resulting in a simple and efficient process. The regenerated lithium cobalt oxide material not only recovers its capacity but also achieves a significant leap in high-pressure cycling performance, with its long-term cycling stability at 4.5V far exceeding that of materials regenerated solely through lithium replenishment. Attached Figure Description

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments;

[0023] Figure 1 The images show the XRD patterns of waste lithium cobalt oxide (SLCO), repaired lithium cobalt oxide MP in Example 1 of this invention, and material RLCO in Comparative Example 1.

[0024] Figure 2 SEM images of waste lithium cobalt oxide (SLCO), repaired lithium cobalt oxide MP in Example 1 of this invention, and material RLCO of Comparative Example 1.

[0025] Figure 3 The graph shows the cycle performance of waste lithium cobalt oxide (SLCO), repaired lithium cobalt oxide MP in Example 1 of this invention, and material RLCO in Comparative Example 1 under the condition of 4.5V 1C.

[0026] Figure 4 The above figures show the rate performance of the repaired sample MP and the material RLCO in Comparative Example 1 of this invention. Detailed Implementation

[0027] Example 1

[0028] Method for preparing high-voltage lithium cobalt oxide cathode materials by modifying and regenerating spent lithium cobalt oxide batteries under normal pressure

[0029] 1) Take 1g of waste lithium cobalt oxide battery powder, and measure its residual aluminum content to be 2.8mg. Add 34mg of lithium carbonate as lithium source (the amount of lithium source added is 5% more than the amount of lithium missing in the waste lithium cobalt oxide battery powder), and 4mg of magnesium oxide as magnesium source (the amount of magnesium source added satisfies the molar ratio of magnesium to residual aluminum in the mixture to be 1:1). All raw materials are dry mixed in a planetary ball mill for 6 hours to obtain the mixture.

[0030] 2) The mixture was placed in an oxygen atmosphere furnace with atmospheric pressure, and heated to 850°C at a rate of 3°C / min. After holding at this temperature for 10 hours, it was cooled with the furnace to obtain the high-pressure lithium cobalt oxide cathode material MP.

[0031] like Figure 1 As shown, the lithium cobalt oxide cathode material MP exhibits an α-NaFeO2 type layered structure in the X-ray diffraction pattern, and the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak, I(003) / I(104), is greater than 1.2.

[0032] Example 2

[0033] Method for preparing high-voltage lithium cobalt oxide cathode materials by modifying and regenerating spent lithium cobalt oxide batteries under normal pressure

[0034] 1) Using waste lithium cobalt oxide battery powder as raw material, its residual aluminum content was determined and based on this, lithium source (lithium hydroxide) and magnesium source (magnesium hydroxide) were added according to stoichiometric ratio. The amount of lithium source added was 5% more than the amount of lithium missing in the waste lithium cobalt oxide battery powder, and the amount of magnesium source added was such that the molar ratio of magnesium to residual aluminum in the mixture was 1:0.2. All raw materials were dry mixed in a planetary ball mill for 6 hours to obtain the mixture.

[0035] 2) Place the mixture in an oxygen atmosphere furnace with atmospheric pressure, heat it to 900℃ at 3℃ / min, hold it at that temperature for 15h, and then cool it to obtain the regenerated high-voltage lithium cobalt oxide cathode material.

[0036] Example 3

[0037] Method for preparing high-voltage lithium cobalt oxide cathode materials by modifying and regenerating spent lithium cobalt oxide batteries under normal pressure

[0038] 1) Using waste lithium cobalt oxide battery powder as raw material, its residual aluminum content is determined and based on this, lithium source (lithium nitrate) and magnesium source (magnesium nitrate) are added according to stoichiometric ratio. The amount of lithium source added is 10% more than the amount of lithium missing in the waste lithium cobalt oxide battery powder, and the amount of magnesium source added meets the molar ratio of magnesium to residual aluminum in the mixture of 1:5. All raw materials are dry mixed in a planetary ball mill for 8 hours to obtain the mixture.

[0039] 2) Place the mixture in an oxygen atmosphere furnace with atmospheric pressure, heat it to 750℃ at 3℃ / min, hold it at that temperature for 16h, and then cool it to obtain the regenerated high-voltage lithium cobalt oxide cathode material.

[0040] Comparative Example 1

[0041] Take 1g of waste lithium cobalt oxide battery powder, add the same amount of lithium carbonate as in Example 1, and dry mix all raw materials in a planetary ball mill for 6 hours to obtain a mixture. Place the mixture in an oxygen atmosphere furnace with an air pressure of atmospheric pressure, heat it to 850°C at 3°C / min, hold it at that temperature for 10 hours, and then cool it with the furnace to obtain a new material RLCO that only requires a supplemented lithium source.

[0042] Comparative Example 2

[0043] Take 1g of waste lithium cobalt oxide battery powder, place it in an oxygen atmosphere furnace, with the gas flow pressure at atmospheric pressure, heat it to 850℃ at 3℃ / min, hold it at that temperature for 10 hours, and then cool it with the furnace to obtain unrepaired waste lithium cobalt oxide material SLCO.

[0044] Performance testing

[0045] (1) Electrodes were fabricated using the materials prepared in Example 1 and Comparative Examples 1 and 2, respectively, with lithium metal as the negative electrode, and long-cycle tests were conducted at a voltage of 3.0-4.5V and a 1C rate. The results are as follows:

[0046] Material MP: Initial discharge capacity 158 mAh / g, capacity retention 86% after 400 cycles.

[0047] Material RLCO (lithium replenishment only): initial discharge capacity 151 mAh / g, capacity retention 85% after 400 cycles, and minimal performance degradation.

[0048] Material SLCO (waste lithium cobalt oxide): completely scrapped, with an initial capacity of only 47 mAh / g.

[0049] (2) Rate testing was conducted at a voltage of 3.0-4.5V. The results are as follows:

[0050] Material MP: Capacity decay is not significant at high rates.

[0051] Material RLCO (lithium supplement only): Severe capacity loss at high rates.

[0052] Results Analysis: The lithium cobalt oxide cathode material MP regenerated by the method of this invention exhibits superior high-voltage cycle stability compared to RLCO regenerated only by lithium replenishment, but significantly better rate performance. Simultaneously, the addition of Mg greatly reduces battery polarization, demonstrating that Al / Mg synergistic modification effectively stabilizes the crystal structure and broadens the lithium-ion transport channels. This stems from the unique distribution of residual Al in the original crystal lattice and the reintegration effect during the heat treatment process.

Claims

1. A method for preparing high-voltage lithium cobalt oxide cathode material by modifying and regenerating spent lithium cobalt oxide batteries under normal pressure, characterized in that, Includes the following steps: 1) Using waste lithium cobalt oxide battery powder as raw material, determine its residual aluminum content and, based on this, add lithium source and magnesium source according to stoichiometric ratio, and mix evenly to obtain a mixture. 2) The mixture is sintered once in an oxygen-containing atmosphere at a temperature of 750-950℃ for 10-20 h. After cooling, the recycled high-voltage lithium cobalt oxide cathode material is obtained.

2. The method for preparing high-voltage lithium cobalt oxide cathode material by modifying and regenerating spent cobalt oxide batteries under normal pressure according to claim 1, characterized in that, The lithium source is at least one of lithium carbonate, lithium hydroxide, lithium nitrate or lithium acetate, and the amount of lithium source added is 3%-10% more than the amount of lithium missing in the waste lithium cobalt oxide battery powder.

3. The method for preparing high-voltage lithium cobalt oxide cathode material by modifying and regenerating spent cobalt oxide batteries under normal pressure according to claim 1, characterized in that, The magnesium source is at least one of magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium nitrate, or magnesium citrate, and the amount of magnesium source added satisfies the molar ratio of magnesium to residual aluminum in the mixture being 1:0.2-1:

5.

4. The method for preparing high-voltage lithium cobalt oxide cathode material by modifying and regenerating waste lithium cobalt oxide batteries under normal pressure according to claim 1, characterized in that, Step 1) The mixing is carried out by mechanical chemical ball milling for 2-8 hours; Step 2) The sintering temperature is 850℃-900℃.

5. The method for preparing high-voltage lithium cobalt oxide cathode material by modifying and regenerating waste lithium cobalt oxide batteries under normal pressure according to claim 1, characterized in that, The oxygen-containing atmosphere mentioned in step 2) is oxygen or air, and the airflow pressure is normal pressure.

6. The regenerated high-voltage lithium cobalt oxide cathode material obtained by the method according to any one of claims 1-5.

7. The regenerated high-voltage lithium cobalt oxide cathode material according to claim 6, characterized in that, The regenerated high-voltage lithium cobalt oxide cathode material, under a cutoff voltage of 4.5V and a charge-discharge cycle test at a 1C rate, exhibits a capacity retention rate of no less than 85% after 400 cycles.

8. The regenerated high-voltage lithium cobalt oxide cathode material according to claim 6, characterized in that, The regenerated high-voltage lithium cobalt oxide cathode material shows an α-NaFeO2 type layered structure in the X-ray diffraction pattern, and the intensity ratio of the (003) crystal plane diffraction peak to the (104) crystal plane diffraction peak, I(003) / I(104), is greater than 1.

2.

9. A positive electrode sheet for a lithium-ion battery, characterized in that, It comprises the regenerated high-voltage lithium cobalt oxide cathode material as described in claim 6.

10. A lithium-ion battery, characterized in that, It comprises the lithium-ion battery positive electrode sheet as described in claim 9.

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