Overdischarge of Spent Lithium Ion Batteries Induced Copper Deposition Onto Cathode for Better Upcycling

Abstract

An efficient recycling strategy is of importance for reducing the environmental impact of spent lithium-ion batteries (LIBs), alleviating resource shortages, and achieving high-value utilization of battery waste. State-of-the-art materials upcycling enables the transformation of spent battery materials into advanced materials with improved performance through modification with external substances. In this work, we introduce an upcycling strategy based on spent LIBs overdischarge, which enables the incorporation of Cu and Li from the anode into LiCoO₂ for the construction of modified LiCoO₂ with structural stability and rate performance. During overdischarge, the anode potential reaches the oxidation potential of Cu foil, generating Cu ions that migrate under the electric field and deposit on the cathode. Simultaneously, lithium from the decomposition of the solid electrolyte interphase on the anode supplements the lithium deficiency in LiCoO₂. These Cu and Li, combined with cathode electrolyte interphase (CEI) species formed during cycling and Al contamination introduced during the recycling process, contribute to the formation of CEI phases and Cu coated, and Al and Cu doped LiCoO₂ with a stable interface and improved ionic transport properties. Compared with commercial and degraded materials, the upcycled cathode exhibits obvious advantages, delivering an initial capacity of 164.04 mAh g⁻¹ and maintaining 97.4% capacity retention after 300 cycles at 0.5 C. At high current densities of 2 C and 5 C, the material retains capacities of 147.2 mAh g⁻¹ and 132.6 mAh g⁻¹, respectively. This study demonstrates that introducing beneficial elements during the recycling of spent LIBs enables concurrent improvements in battery performance, cost efficiency, and resource utilization.