In recent years, in response to the global environmental crisis and reducing carbon emissions, countries are actively promoting new energy vehicles. According to statistics, since 2014, when new energy vehicles entered the passenger car market, the production and sales of new energy vehicles have been increasing.
As of 2023, the production and sales of new energy vehicles in China have approached 10 million units, and the share of new energy vehicles in China's auto market has exceeded 30%. It is worth noting that according to the average service life of power batteries of 5-8 years, the power batteries of new energy vehicles promoted in China in the early days have entered the "retirement" period.
If used batteries are not properly disposed of, the heavy metals and harmful chemicals they contain will cause serious pollution to soil and water resources, threatening the balance and stability of the entire ecosystem.
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It is estimated that by 2030, more than 3 million tons of waste power batteries will be generated by new energy vehicles, but the standardized recycling rate of new energy vehicle power batteries in China is less than 30%. Therefore, the recycling and treatment of waste power batteries has become the focus of attention in the industry.
On May 14, 2024, mainland scientists published an article on the sustainable recycling of retired power batteries in the journal Nature Sustainability, which is expected to accelerate the promotion and application of advanced recycling technologies for power batteries and promote the rapid commercialization and development of the battery recycling industry.
The findings were published in the journal Nature Sustainability (Image source: Nature Sustainability)
In this study, the authors used leaching and co-precipitation to extract high-value metal elements from lithium battery cathode materials and regenerate electrodes. In the leaching process, the authors selectively dissolved the high-value metal elements in the cathode materials of lithium batteries, including lithium, cobalt, nickel and manganese, by taking advantage of the different dissolution efficiency of different metal elements in acetic acid, and then obtained clear and transparent leachate by filtration.
In order to maximize the high added value of the cathode elements of lithium batteries, the authors used a mixed solution of ammonia and sodium hydroxide to co-precipitate the leaching solution to prepare spherical precursors in a continuous stirred tank reactor.
Among them, ammonia can be used as a chelating agent to form metal-ammonia complexes with transition metals in the leaching solution to prevent phase precipitation in the co-precipitation process. In the co-precipitation process, more than 99.8% of the high-value metals, in addition to lithium ions, are recovered by spherical precursors with design ratios of nickel, cobalt, and manganese. Finally, the regenerated R-NCM cathode material was obtained by high-temperature lithiation reaction.
Extraction of high-value elements (a. the relationship between the dissolution efficiency of metals and the concentration of slurry; b. the comparison of the dissolution efficiency of metals in lithium batteries by different types of acid solutions; c. vacuum-assisted filtration. (Image source: Ref. 1)
The experimental results show that the R-NCM regenerated cathode material exhibits high reversible capacity and high coulombic efficiency (>99.7%). In terms of stability, the cathode material has a capacity retention rate of 81.2% after 500 charge-discharge cycles, which is better than that of commercial NCM cathode materials (capacity retention rate of 50.1%), and the regenerated cathode material retains the spherical structure of the precursor, with minimal microcracks and strong phase stability during cycling.
Compared with commercial NCM cathode materials, the production and use of R-NCM renewable cathode materials can effectively reduce the potential of global warming and the scarcity of fossil resources. In terms of battery cost, the use of R-NCM renewable cathode materials can reduce the manufacturing cost of lithium-ion battery packs and sodium-ion battery packs by $21.65 per kWh and $41.67 per kWh, respectively.
Lithium-ion battery regeneration cathode material (a. SEM image and elemental distribution map of spherical R-NCM powder, nickel (blue), cobalt (pink) and manganese (green) with a scale of 1 μm; b. 2D GIXRD image, c. K-boundary XANES spectra of nickel, d, e, f. electrochemical performance characterization results, g. cross-sectional FIB electron microscope image of commercial NCM electrode and R-NCM electrode after cycling with 1 μm bar, h. In-situ XRD image of R-NCM electrode and corresponding cycle curves, i. 3D reconstruction of representative materials on the electrode surface. (Image source: Ref. 1)
At present, lithium batteries are recycled and reused
What else is being done?
The recycling and reuse of lithium batteries refers to the dismantling of retired lithium batteries through chemical, physical, biological and other means to achieve the purpose of recovering metal elements such as nickel, cobalt, manganese, lithium and other recyclable materials. At present, the methods of lithium battery recycling and reuse mainly include wet recycling, fire recycling and biological recycling.
Wet recovery refers to the selective dissolution of metals in electrode materials with chemical reagents, and then the separation of metal elements in the leaching liquid. This technology has the advantages of high recovery rate, high product purity and low energy consumption, and is currently the most widely used recycling technology.
Pyrometallurgical recovery refers to the removal of impurities from waste batteries by high-temperature means, and finally extracts fine powdery materials containing metals and their compounds. The operation process of this technology is simple, the efficiency is relatively high, and it is suitable for processing a large number of batteries or complex structures.
Biological recycling refers to the selective leaching of metal elements from waste batteries by using the metabolic process of microorganisms to achieve the purpose of extracting high-value metal elements. The technology is environmentally friendly, but it is still in the research and development stage and the technology is not yet mature.
Lithium battery environmental recycling
The impact on our lives?
1. Environmental protection
Lithium battery recycling can significantly reduce the environmental pollution caused by used batteries. Through professional recycling and processing, it can prevent harmful substances in waste batteries, such as heavy metals, organic solvents, etc., from leaking into the environment, and protect soil and water resources.
2. Resource conservation
Lithium-ion battery recycling enables the reuse of high-value and rare materials. For example, recycled metal elements such as lithium, nickel, and cobalt can be used as raw materials to produce new batteries after refining and purifying, reducing production costs and saving resources.
In addition, recycled battery chips and electrolytes can also be recycled and reused, further improving resource efficiency.
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epilogue
As a new choice for environmentally friendly travel, new energy vehicles have not only brought revolutionary changes to our travel mode, but also made great contributions to environmental protection. Although the recycling technology of waste batteries can alleviate the pollution of waste batteries to the environment to a certain extent, it still advocates that we develop good car habits in our daily life, prolong the service life of batteries, reduce the production of waste batteries, and contribute to the global environment.
bibliography
[1] Yang, T., Luo, D., Zhang, X. et al. Sustainable regeneration of spent cathodes for lithium-ion and post-lithium-ion batteries. Nat Sustain, 2024.
[2] HE Hongkai, WANG Yuewei, CHEN Chaofang, et al. Guangzhou Chemistry, 2014, 39(4):6.
[3] Li Xiang, Fan Jiayue, Zhu Xinyi. Industrial Innovation Research, 2023(19):11-13.
[4] Ferrara C , Ruffo R , Quartarone E ,et al. Circular Economy and the Fate of Lithium Batteries: Second Life and Recycling[J]. Advanced Energy and Sustainability Research, 2021.
Planning and production
Produced by丨Popular Science China
Author丨Shi Chang, Ph.D. in Physical Chemistry
Producer丨China Science Expo
Editor-in-charge丨Yinuo
Reviewer丨Xu Lai Linlin