Molten Salt-Assisted Synthesis of Single-Crystalline NCM523 Cathodes from Spent Precursors: High-Performance and Cost-Effective Recycling

The booming electric vehicle market underscores the pressing need for lithium-ion battery (LIB) recycling due to its finite lifespan. While traditional recycling is energy-intensive and complex, direct regeneration offers a promising alternative, though it struggles to remedy irreversible polycrystalline damage. In this context, we propose a molten salt-assisted direct upcycling strategy, which successfully converts spent polycrystalline LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) into a single-crystal structure by using a slightly excessive LiOH-Li 2 CO 3 molten salt system (only 10% excess to compensate lithium salt loss at high temperatures), and the upcycled NCM523 demonstrates electrochemical performance comparable to commercial level, delivering a discharge capacity of 163.083 mA h g –1 at 0.1 C and retaining 90.33% of its capacity after 100 cycles. Furthermore, the cost analysis indicates that direct upcycling requires only 14.07 $ kg –1, significantly lower than that of manufacturing cathodes from virgin materials. This strategy leverages the thermal dynamics of slightly excessive molten salts to achieve controlled transformation of polycrystalline NCM into single-crystal structures, and unlike previous regeneration approaches that primarily focus on morphological control, this method not only effectively restores electrochemical performance but also emphasizes practical economic viability in production, which provides a pathway for scaled-up and high-value recycling of spent cathode materials.