NaTiO2: a layered anode material for sodium-ion batteries

Lithium-ion batteries are currently the energy storage technology of choice in portable electronic devices and electric vehicles. In recent years, sodium-ion batteries have been actively restudied as a promising alternative because of the abundance of sodium resources and the high capacity cathodes available. But as graphitic carbon can not be used as anode material, as it is in lithium batteries, the design of the novel Na-ion anode materials with high capacity and cycling-stability is critical for the We report on layered NaTiO2 as a potential anode material for Na-ion batteries. The material is prepared from only earth-abundant elements, delivers 152 mA h g 1 of reversible capacity at C/10 rate, shows excellent cyclability with capacity retention over 98% after 60 cycles, and high rate capability. Furthermore, in situ X-ray diffraction analysis reveals a reversible O3–O03 phase transition, including an unusual lattice parameter variation coupled to complicated Na vacancy orderings in a series of 2nd order phase transitions.