Roles of Impurities on Recovered Li-NCM Cathode Materials in Hydrometallurgy Recycling

Zheng, Yadong

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Roles of Impurities on Recovered Li-NCM Cathode Materials in Hydrometallurgy Recycling

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The lithium-ion batteries (LIBs) have become an integral part of our life because of their light weight, high energy density, and long cycle life, suitable in powering smart phones and laptops that have revolutionized modern society. Massive use of LIBs has resulted in a huge demand for raw materials. Besides, large amount of waste batteries could threaten human health and environment. As such, recycling is regarded as an end-of-pipe process to resolve sustainability and environmental concerns. The hydrometallurgy recycling has been the focus of attention due to its high recovery efficiency, low energy costs, and large production capability. It includes battery shredding, sieving, acid leaching, and leachate tuning. Then, the metal sulfate leachate, which contains elements that are intended to be recovered, is used to synthesize precursor by co-precipitation. Lastly, cathode material is obtained by sintering a mix of precursor and lithium source. A variety of impurities could potentially be introduced into the leachate. In order to achieve stable, high-quality recovered cathode, many efforts have been made to improve the design and control of hydrometallurgy. Thus, the presence of impurities is a matter of concern, as it will have unintended impacts on the final product. There are three types of impurities: cations, solid particles, and anions, which originate from dissolved metal debris, additives, or other battery materials. This research provides a comprehensive insight into the impacts of impurity on the LiNi0.6Co0.2Mn0.2O2 (“NCM622”) cathode via hydrometallurgy method. Herein, selected impurities (Al, C, Fe, F, and P) are added in the process to obtain doped materials. By comparing with virgin reference, changes in as-prepared cathodes due to the addition of impurity will be analyzed and summarized in detail. The findings from this study systematically uncover the roles of impurities in hydrometallurgy. This serves as a critical guide for optimizing hydro recycling technique in order to maximize the recycling benefits.

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