Overcharge protection of lithium-ion batteries with phenothiazine redox shuttles

Abstract

Overcharge in lithium-ion batteries (LIBs) can be mitigated using electron-donating small molecules with oxidation potentials just above the end-of-charge potential of the electrochemical cell. These additives function by oxidizing at the cathode/electrolyte interface, forming radical cations, and are then reduced at the anode/electrolyte interface, becoming neutral again. A variety of redox shuttles have been reported since 2005 including derivatives of TEMPO, alkoxybenzene, and phenothiazine. This perspective focuses on phenothiazines redox shuttles and their performance in LIBs.