Repurposing of spent lithium-ion battery separator as a green reductant for efficiently refining the cathode metals

Wei Hou; Xuanrui Huang; Rui Tang; Yulin Min; Qunjie Xu; Zhenhu Hu; Penghui Shi

doi:10.1016/j.wasman.2022.11.002

Repurposing of spent lithium-ion battery separator as a green reductant for efficiently refining the cathode metals

Waste Manag. 2023 Jan 1:155:129-136. doi: 10.1016/j.wasman.2022.11.002. Epub 2022 Nov 10.

Authors

Wei Hou¹, Xuanrui Huang¹, Rui Tang², Yulin Min³, Qunjie Xu³, Zhenhu Hu⁴, Penghui Shi⁵

Affiliations

¹ Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, PR China.
² Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200090, PR China. Electronic address: tangrui@shiep.edu.cn.
³ Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200090, PR China.
⁴ Anhui Engineering Laboratory of Rural Water Environment and Resource, School of Civil Engineering, Hefei University of Technology, Hefei 230009, PR China.
⁵ Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, Shanghai University of Electric Power, Shanghai 200090, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200090, PR China. Electronic address: shipenghui@shiep.edu.cn.

PMID: 36370622
DOI: 10.1016/j.wasman.2022.11.002

Abstract

Developing green and high-efficient pyrometallurgy processes to recycle precious metals from spent lithium-ion batteries (LIBs) is of great importance for resource sustainability and environmental protection. Herein, a novel reduction roasting approach relying on spent LIB separator to refine the spent cathode is proposed. The efficiency of repurposing separator as a reductant for roasting the spent LiCoO₂ cathode and the underlying mechanisms were investigated. After the separator-mediated roasting at 500 °C for 2 h, Li⁺ leaching efficiency of the cathode reached 93.2 %, >2.6 times higher than those after roasting without reductant (25.2 %) or with benchmark reductant graphite (26.1 %). Under the separator-added roasting condition, the cathode was converted to the desired products, CoO and Li₂CO₃. Based on the analysis of in-situ reaction using thermogravimetric/differential scanning calorimetry and pyrolysis gas species identification, the separator-mediated reduction roasting of cathode was composed of two stages, i.e., reducing gas generation due to separator pyrolysis, followed by the reducing gas mediated LiCoO₂ reduction. During the process, the generated C₂H₄ and CO dominated the reduction. The use of co-existing separator to recover precious metals from spent LIBs is an effective and sustainable strategy to maximize the utilization of spent LIBs.

Keywords: Li(+) leaching; Pyrolysis; Reduction roasting; Separator; Spent lithium-ion batteries.