Efficient Stabilization of Na Storage Reversibility by Ti Integration into O3-Type NaMnO2
(a) Quasi-open-circuit voltage curves of the samples of (a) and 0.8 at the initial cycle. Rate capability of the samples is also shown in (b); sample loading, 4.38 mg cm–2 for and 4.66 mg cm–2 for . (c) Capacity retention of the sample of measured with/without constant voltage (CV) holding at 4.2 V for 2 h after being charged at a constant current (CC) of 4.2 V. Charge/discharge curves of the sample with voltage holding are shown in the inset. (d) An accelerated cycle test at a rate of 50 mA g-1. CV holding at 4.2 V for 30 min was applied on charge. Initial and last 3 cycles were cycled at a rate of 20 mA g-1.