Efficient extraction of Mn2+ ions from the waste produced in the Hummers method for application in Li-ion batteries

Abstract

Graphene nanosheets are produced in mass by Hummers method, accompanied with the emission of waste acid effluent with Mn2+, which should be reasonably recycled. Herein, Mn2+ was extracted into Mn3O4 nanoparticles by oxidation precipitation. Desirably, Mn3O4 powders were the spinel crystal phase and the particle size was 100-150 nm. The reversible discharge capacities of Mn3O4 anode maintained 528 mAh/g at 0.5 A/g for 100 cycles and 423 mAh/g at 1.0 A/g for 300 cycles, with high capacity retention ratios of 93.4 % and 91.1 %, respectively. Obviously, this work may promote the development of the circular economy.