Zeshan Alam, Shabbir H. Gheewala
The rapid expansion of electric vehicles creates a new sustainability challenge: managing used lithium-ion batteries that no longer meet vehicle requirements but still retain capacity for lower-demand uses. Used EV batteries can extend material value, reduce waste, support renewable energy integration, and advance circular economy transitions. However, they are not automatically sustainable. Their benefits depend on accurate state-of-health assessment, safety screening, lifecycle data, economic feasibility, social acceptance, circular business models, and eventual recycling. Hence, the central argument of this perspective is that used EV batteries should be managed through conditional circularity; reuse should be prioritized over recycling only when residual performance, safety, lifecycle environmental benefit, economic feasibility, data traceability, and final recycling responsibility can be demonstrated. Recent studies show potential applications in stationary storage, microgrids, renewable energy systems, and energy access, but barriers remain, including degradation uncertainty, thermal safety, standardization, data transparency, and market confidence. The main contribution of this perspective is a lifecycle decision framework for operationalizing conditional circularity in used EV battery management. The framework links battery diagnostics, sustainability assessment, planetary-boundary thinking, circular business models, risk assessment, AI-enabled battery management, and final recycling responsibility to determine when reuse, cascading, or direct recycling is the most responsible pathway.