High lithium storage performance of Ni 0.5 Fe 0.5 O 1− x N x thin film with NiO-type crystal structure

The large voltage hysteresis of the NiO anode, which owes much to the intermediate product Li 2 NiO 2 , is one of the main obstacles to its practical application in lithium-ion batteries. In this work, we show that the incorporation of Fe- and N-ions in the NiO lattice can suppress the formation of intermediate product Li 2 NiO 2 and thus greatly reduces the voltage hysteresis of the NiO anode from ∼1.2 to ∼0.9 V. In comparison with the pure NiO electrode, the Ni 0.5 Fe 0.5 O 1− x N x anode exhibits significantly enhanced reversible specific capacity (959 mAh·g −1 at 0.3 A·g −1 ), cycling stability (capacity retention of 96.1% at 100th cycle relative to the second cycle) and rate capability (442 at 10 A·g −1 ). These results provide a practical method to enhance the lithium storage performance of the NiO anode and more importantly a new solution to the large voltage hysteresis of conversion-type anodes.