Exploration of Ca 0.5 Ti 2 (PO 4 ) 3 @carbon Nanocomposite as the High-Rate Negative Electrode for Na-Ion Batteries

Exploring suitable electrode materials with high specific capacity and high-rate capability is a challenging goal for the development of Na-ion batteries. Here, we report a NASICON-structured compound, Ca Ti (PO ) , with respect to its synthesis and electrochemical properties. The electrode is found to enable fast Na ion diffusion owing to the rich crystallographic vacancies, affording a reversible capacity of 264 mA h g between 3.0 and 0.01 V. In particular, the hybrid Ca Ti (PO ) @carbon exhibits remarkable rate performance with a discharge capacity of nearly 45 mA h g at a current density of 20 A g , which is attributed to the pseudocapacitive effect.