Molten salt-assisted regeneration and characterization of submicron-sized LiNi0.5Co0.2Mn0.3O2 crystals from spent lithium ion batteries

Abstract

Nowadays the increasing demand of energy storage devices leads to consumption of a large number of lithium-ion batteries (LIBs), it is an urgent topic about how to deal with the large quantity of discarded LIBs. In this work, the spent-LiNi0.5Co0.2Mn0.3O2 (SNCM) cathode material was directly re-synthesized by one-pot molten salt-assisted regeneration. The effect of various quantity ratios of molten salts and the spent-LiNi0.5Co0.2Mn0.3O2 (SNCM) material on preparation and electrochemical properties of the regenerated submicron-sized LiNi0.5Co0.2Mn0.3O2 crystals has been studied in detailed. The lithium deficiency, degraded crystal structure and impure surface of SNCM are successfully restored in liquid medium of lithium-contained molten salt. The structural restoring, structure stability and capacity recovering of the regenerated samples are determined by the environment of molten salts. The optimized regenerated sample MS1.1 delivers the highest initial capacity of 152.5 mAh g−1 at 0.2 C rate, and it remains 86% capacity after 100 cycles. MS1.1 with the smallest charge transfer resistance delivers the highest capacity of 133.4 mAh g−1 at 5 C rate, and it presents excellent cyclic stability for 500 cycles. After 100 cycles, stable crystal morphology of MS1.1 is still maintained, and MS1.1 induces less side reactions and low quantity of by-products. The restored electrochemical performances of MS1.1 sample prove that the molten salt-assisted regeneration maybe a facial and effective method for other spent cathode materials.