Recycling lithium-ion batteries (LIBs) can supplement existing supplies of critical materials and improve the environmental sustainability of LIB supply chains. In this work, environmental intensities (greenhouse gas emissions, water consumption, energy consumption) of industrial-scale production of battery-grade cathode materials from used LIBs are compared to the intensities of conventional mining supply chains. Refining mixed-stream LIBs into battery-grade materials reduces these environmental intensities by at least 55%. Electricity consumption is identified as the principal contributor to all LIB recycling environmental intensities, and different electricity sources can change greenhouse gas emissions up to eight times. Supply chain steps that precede refinement (material extraction and transport) contribute marginally to the environmental intensities of circular LIB supply chains (<5%), but are more significant in conventional supply chains (31%). This analysis disaggregates conventional and circular steps based on material extraction, transport, and industrial refinement operations to provide important insights for advancing sustainable LIB supply chains.