Communication—Ligand-Dependent Electrochemical Activity for Mn2+in Lithium-Ion Electrolyte Solutions

Manganese dissolution from metal-oxide cathodes, and subsequent deposition at graphitic anodes, are considered to be key causes of capacity fade in lithium-ion batteries. The Mn 2+ redox state is thought to be the major solvated Mn species, but its coordination environment is not well understood. Herein, we present the effects of Mn 2+ -containing electrolytes (Mn(PF 6 ) 2 and Mn(TFSI) 2 ) on the performance of lithium-iron-phosphate//graphite (LFP//Gr) cells. Clear differences in first-cycle capacities and subsequent cycling efficiencies depending on the associated counter-ion indicate that the Mn coordination environment has a profound effect on the associated electrochemical degradation mechanisms.