A closed-loop regeneration of LiNi0.6Co0.2Mn0.2O2 and graphite from spent batteries via efficient lithium supplementation and structural remodelling

Abstract

The recycling and regeneration of spent lithium nickel cobalt manganese oxides (NCMs) are highly valued, due to the scarcity of raw materials and high cost of the synthetic process. Nevertheless, most current investigations are mainly focused on the recycling of NCMs with low nickel content (e.g. NCM111 or NCM 523), and there are hardly any reports on the corresponding research on high nickel NCMs. Herein, we report a novel closed-loop method to realize the simultaneous regeneration of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) and graphite electrode materials from spent batteries. By adding an appropriate amount of lithium sources and designing a segmental calcination process, the depleted lithium in the spent NCM622 material is efficiently supplemented, and the collapsed structure of NCM622 is simultaneously remodelled. The spent graphite is also reconstructed by pretreatment and annealing at the same time. The regenerated NCM622 and graphite used in a new full cell deliver a reversible capacity of 151.4 mA h g⁻¹ after 100 cycles at 0.2C with a capacity retention of 95.6% and gradually improved coulombic efficiency, exhibiting battery performance comparable to that of new commercial batteries. The solid phase regeneration method proposed in this paper will provide strong support for the sustainable development of power lithium ion batteries, especially in industrial applications.