Study on the thermal reduction effect of organic components in spent ternary lithium battery cathode active materials

Haidi Jiang; Zhaohui Li; Weining Xie; Guangwen Zhang; Zhaoyi Yu; Qichang Lu; Yaqun He

doi:10.1016/j.wasman.2022.05.011

Study on the thermal reduction effect of organic components in spent ternary lithium battery cathode active materials

Waste Manag. 2022 Jul 1:148:33-42. doi: 10.1016/j.wasman.2022.05.011. Epub 2022 May 31.

Authors

Haidi Jiang¹, Zhaohui Li¹, Weining Xie², Guangwen Zhang³, Zhaoyi Yu¹, Qichang Lu⁴, Yaqun He¹

Affiliations

¹ School of Chemical Engineering and Technology, China University of Mining &Technology, Xuzhou, Jiangsu 221116, China.
² School of Chemical Engineering and Technology, China University of Mining &Technology, Xuzhou, Jiangsu 221116, China; Advanced Analysis and Computation Center, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China. Electronic address: aacc_xwn5718@cumt.edu.cn.
³ School of Environment Science and Spatial Informatics, China University of Mining &Technology, Xuzhou, Jiangsu 221116, China.
⁴ Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, Qinghai 810008, China.

PMID: 35660255
DOI: 10.1016/j.wasman.2022.05.011

Abstract

To improve the adhesion between cathode materials and current collector, and increase the electronic conductivity among electroactive substances, a certain proportion of conductive agents (acetylene black) and agglomerant (PVDF) are usually added in the battery manufacturing process. However, these conductive agents have negative effects on the recovery of cathode materials by pyrolysis or calcination. Recognizing this issue, a method based on the concept of "treating spent with spent" was developed in this paper. Organic matters contained in cathode active materials functioned as the reduction reagents, which can reduce the valence state of transition metals, resulting in the breakdown of the strong chemical bond and the stable layered structure of cathode materials. In this study, the thermal reduction effect of different organic components on cathode active materials was analyzed respectively to evaluate the reduction function of each component. XRD, XPS and ICP-MS were used to compare and analyze changes of phase, element compound state and ion leaching efficiencies of different cathode materials before and after thermal reduction under different amounts of reducing agents. The results show that both PVDF and acetylene black reduced the high-valent metals to low-valent oxides or elemental substances, demonstrating their thermal reduction capabilities. Comparisons of the XRD, XPS analysis and ion leaching results of thermal reduced products suggest that acetylene black has a stronger thermal reduction ability than that of PVDF. The results also show that the reduction of the high nickel cathode material (NCM811) is easier than that of the low nickel cathode material (NCM111).

Keywords: Cathode material; In-situ thermal reduction; Spent ternary lithium battery.