Improved Energy Storage Solution Based on Hybrid Oxide Materials

Electrodeposited-oxidized FeCoNi-based electrodes have shown to exhibit enhanced electrochemical behavior in Li cells in terms of first-cycle reversibility and minimal discharge polarization on successive discharges. The latter is referred to as the main faradic conversion reaction taking place at 0.8 V versus Li + /Li 0 in first and consecutive cycling. In this communication, the faradic and capacitive charge-storage capacities are unfolded. The main effect responsible for the high reversibility achievable from first to second discharge is a pseudocapacitive contribution that starts in the second discharge between 1.75 and 1.5 V and compensates for the loss of capacity due to electrolyte decomposition in the previous discharge, thus leading to a high Coulombic efficiency (∼85%). The intensity dependence of the different peak currents with the sweep rate has been extensively examined to understand the differences of capacity contributions in the total charge storage. Specific capacitance for FeCoNi-based film could reach as high as 600 F g –1 .