Na0.5Bi0.5TiO3 perovskite anode for lithium-ion batteries†

Lithium-ion battery technology, currently the most popular form of mobile energy storage, primarily uses graphite as the anode. However, the graphite anode, owing to its low working voltage at high current density, is susceptible to lithium plating and related safety risks. In this direction, perovskite oxides like CaSnO₃, more recently PbTiO₃, have been explored as alternate anode materials due to their higher operational voltage. Extending this family of perovskites, we introduce a widely used lead-free piezoelectric ceramic Na_0.5Bi_0.5TiO₃ (NBT) as a potential anode for lithium-ion batteries. NBT has an average voltage of 0.7 V and a high capacity of 220 mA h g⁻¹. Ex situ diffraction and spectroscopy tools were used to understand the charge storage mechanism. The oxide undergoes an irreversible conversion reaction in the first discharge, followed by reversible (de)alloying of Bi with Li in the subsequent cycles. This material is airstable, with a capacity retention of 82% up to 50 cycles at a high current of 100 mA g⁻¹ without any optimization. Furthermore, limiting the voltage window increases the cycle life to 200 cycles. Perovskite-type Na_0.5Bi_0.5TiO₃ is proposed as a new Bi-based conversion alloying anode for lithium-ion batteries.