A Review of Secondary Utilization of Retired Power Battery

The exponential growth of the new energy vehicle industry has driven a surge in global battery installations, leading to a projected 900,000 tons of retired batteries by 2025. While secondary utilization theoretically extends lifecycles compared to direct disposal, persistent pack-level challenges remain. Specifically, issues such as capacity dispersion, resistance escalation, and aging-mode mismatches significantly impede rapid grading and reliable regrouping. Although current capabilities excel in data-driven sorting, critical gaps persist regarding standardization, cost realism, and large-scale safety validation. Consequently, this review compares the trade-offs of four end-of-life routes: pyrometallurgy offers robustness but entails high energy and lithium losses; hydrometallurgy achieves high purity yet relies on chemical additives; direct regeneration enables low-carbon structural restoration but is limited by feedstock cleanliness; and electro-regeneration facilitates cathode-to-cathode cycling pending specific modifications. Finally, by integrating material-level indicators with techno-economic and policy frameworks, we outline feasible pathways for sustainable secondary utilization.