Microwave processing of spent coin cells for recycling of metallic values

Abstract

Lithium metal batteries are essential energy storage primary batteries in portable electronics. It is necessary to develop an effective recycling method for spent batteries containing valuable Lithium, Manganese, and Carbon values considering resource conservation and environmental concerns. In this study, spent Lithium metal batteries are manually dismantled, followed by Lithium dissolution in distilled water/iso-butyl alcohol mixture, and physical separation of steel and active cathode material. Microwave processing of cathode material comprising MnO2 and Carbon is attempted in pursuit of a short and effective recycling process. Dielectric properties of cathode materials were measured, and good microwave response of cathode material was observed at 900 W, 2.45 GHz. The reduction of MnO2 to MnO and Mn3O4 was attained because of Carbon present in the active cathode material. It was found that Manganese extraction was significantly increased from 9 to 94% on application of microwave treatment, and Lithium carbonate was recovered using water leaching. Microwave-assisted reduction of cathode material followed by citric acid leaching is proposed for the recycling of discarded coin cells. Mass balance and detailed cost calculations revealed that the process is economical, providing a positive net cash flow of 677.76 INR/kg spent coin cell.