Direct-Recycling of LiFePO4 Cathodes from a Hybrid-Electric Bus Battery Via Chemical Relithiation

Abstract

Direct recycling of LiFePO4 (LFP) has environmental benefits as a battery waste management strategy, but its efficacy and scalability have yet to be fully understood. As the use of LFP is projected to grow significantly by 2030, it is essential to understand the factors affecting the performance of recycling processes and the quality of their products.This work examines the effectiveness of chemical relithiation on LFP cells of various states-of-health. The work expands on statistical analyses and materials characterization of the cells that were previously presented.1,2 In the previous work, we conducted diagnostic experiments on cells ranging from healthy as-purchased cells to used cells with less than 20% of their initial capacity. The used cells are sampled from a retired hybrid-electric city bus battery pack comprising A123 1536 cells manufactured between 2009 and 2017. Characterization techniques included constant-current cycling, EIS, XRD, and SEM.In this talk, we will discuss methods for direct-recycling LFP cathodes, such as the refunctionalization protocols designed by Ganter et al.3 We will summarize the dependency between various states-of-health and the yield and performance of directly recycled LFP cathode material. Correlations between the efficacy of direct recycling and battery diagnostic information (e.g., percent of initial capacity, direct-current internal resistance, alternating-current impedance, SEM, and XRD) are of particular interest. We will also discuss the implications of scaling up the chemical relithiation process and combining cathode material from cells of various states-of-health. Ramirez-Meyers, K., Rawn, B. & Whitacre, J. (Invited) Statistical Distribution and Feasibility for Re-Use of A123 LiFePO4 Cells from a Hybrid-Bus Battery Pack. PRiME 2020 ECS ECSJ KECS Jt. Meet. MA2020-02, (2020). Ramirez-Meyers, K. & Whitacre, J. Characterization of Used A123 LiFePO4 Cells from a Hybrid-Bus Battery Pack. ECS Meet. Abstr. Vancouver, BC. (2022). Ganter, M. J., Landi, B. J., Babbitt, C. W., Anctil, A. & Gaustad, G. Cathode refunctionalization as a lithium-ion battery recycling alternative. J. Power Sources 256, 274–280 (2014).