Stabilization of xLi[sub 2]MnO[sub 3]⋅(1−x)LiMO[sub 2] Electrode Surfaces (M=Mn, Ni, Co) with Mildly Acidic, Fluorinated Solutions

It has been demonstrated previously that -stabilized electrodes [, , , ] can provide anomalously high electrochemical capacities if charged to high potentials . High-voltage charging results in an irreversible capacity loss on the initial charge/discharge cycle; it also damages the electrode surface, leading to a high cell impedance. In this paper, we report that preconditioning electrode powders [alternatively in notation] with extremely mild acidic solutions of , , and salts in water and methanol (pH 6–6.5) leads to remarkable cycling stability of both lithium half-cells and full lithium-ion cells when repeatedly charged to high voltages . The enhanced electrochemical performance is attributed to stabilized electrode surfaces that are etched and passivated by fluorinated species. The low-temperature behavior of unconditioned and preconditioned electrodes is presented.