Recycling of discarded coin cells for recovery of metal values

Abstract

Lithium-metal primary batteries, widely used in portable electronics, contain lithium, manganese, and carbon, which can be recycled to conserve resources and prevent environmental damage. This study investigates the thermal response of active material under ambient conditions and its effects on manganese dissolution in organic acid. Thus, spent lithium metal batteries were manually dismantled, the lithium they contain was dissolved in a mixture of distilled water and isobutyl alcohol, and the steel and active cathode material were mechanically separated. The thermal exposure of active material comprising MnO2 and C resulted in carbothermal reduction with products Mn3O4 and MnO. The composition of product at optimum condition (800 °C, 30 min) comprises 60 wt% Mn, 21.5 wt% O, and 18.5 wt% C in the form of MnO, Mn3O4, and C. Manganese extraction increased significantly on thermal treatment, yielding 81% at optimum condition. Therefore, thermal treatment for the indigenous reduction of MnO2, followed by leaching in an organic acid, is proposed for lithium and manganese value recovery from spent coin cells. The activation energy for thermal dissociation of active material has been identified as 20.96 kJ/ mol, and mass balance for the process followed has also been investigated.