High temperature molten salts mediated deep regeneration and recrystallization of ternary nickle-rich cathodes

Abstract

Within the framework of carbon neutrality, lithium-ion batteries (LIBs) are progressively booming along with the growing utilization of green and clean energy. However, the extensive application of LIBs with limited lifespan has brought about a significant recycling dilemma. The traditional hydrometallurgical or pyrometallurgical strategies are not capable to maximize the output value of spent LIBs and minimize the potential environmental hazards. Herein, to alternate the tedious and polluting treatment processes, we propose a high-temperature molten-salt strategy to directly regenerate spent cathodes of LIBs, which can also overcome the barrier of the incomplete defects' restoration with previous low-temperature molten salts. The high-energy and stable medium environment ensures a more thorough and efficient relithiation reaction, and simultaneously provides sufficient driving force for atomic rearrangement and grains secondary growth. In consequence, the regenerated ternary cathode (R-NCM) exhibits significantly enhanced structural stability that effectively suppresses the occurrence of cracks and harmful side reactions. The R-NCM delivers excellent cycling stability, retaining 81.2% of its capacity after 200 cycles at 1 C. This technique further optimizes the traditional eutectic molten-salt approach, broadening its applicability and improving regenerated cathode performance across a wider range of conditions.