Insertion reactions in advanced electrochemical energy storage

Abstract

A rechargeable electrochemical energy storage system employing an organic solvent-based electrolyte will be introduced: the lithium-ion cell. The electrode reactions base on Li+-insertion/-removal which ensure high rechargeability. The system possesses an operating voltage of ∼3.5 V and a high energy density. From a thermodynamic viewpoint such a cell is impossible because the used organic electrolyte is in contact with two electrodes that operate at extreme reducing (∼+0.1 V vs. Li/Li+) and oxidizing (∼+4.5 V vs. Li/Li+) potentials, respectively. However, lithium-ion cells perform successfully because a unique mechanism kinetically prevents the decomposition of electrolyte due to the formation of electronically insulating electrode/electrolyte interfaces that are still permeable to the electrochemically active Li+-cations.