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P2-type Na2/3Ni1/3Mn2/3O2 is an air-stable cathode material for sodium-ion batteries. However, it suffers irreversible P2-O2 phase transition in 4.2-V plateau and shows poor cycling stability and rate capability within this plateau. To evaluate the practicability of this material in 2.3–4.1 V voltage range, single-crystal micro-sized P2-type Na2/3Ni1/3Mn2/3O2 with high rate capability and cycling stability is synthesized via polyvinylpyrrolidone (PVP)-combustion method. The electrochemical performance is evaluated by galvanostatic charge-discharge tests. The kinetics of Na+ intercalation/deintercalation is studied detailly with potential intermittent titration technique (PITT), galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV). The discharge capacity at 0.1 C in 2.3–4.1 V is 87.6 mAh g−1. It can deliver 91.5% capacity at 40 C rate and keep 89% after 650 cycles at 5C. The calculated theoretical energy density of full cell with hard carbon anode is 210 Wh kg−1. The moderate energy density associated with high power density and long cycle life is acceptable for load adjustment of new-energy power, showing the prospect of practical application.

The fabrication of high-performance, low-cost photocatalysis materials, which absorb in the visible-light region, is of significance for their practical applications. A Ti2O@TiO2 (rutile) core-shell structure was fabricated through dehydrogenation and oxidation from TiH2. Thermal analysis indicates that a bimodal oxidation behavior accounts for the formation of a bi-phasic composite. The response of the composite under UV and visible light was measured by PL (photoluminescence) spectra and a photo-degradation test. A pronounced improvement in photo-degradation performance is attributed to the synergistic function of exciton separation of the core-shell structure and the visible light response of the Ti2O