Ultrafine MoO2-Carbon Microstructures Enable Ultralong-Life Power-Type Sodium Ion Storage by Enhanced Pseudocapacitance

The achievement of the superior rate capability and cycling stability is always the pursuit of sodium-ion batteries (SIBs). However, it is mainly restricted by the sluggish reaction kinetics and large volume change of SIBs during the discharge/charge process. This study reports a facile and scalable strategy to fabricate hierarchical architectures where TiO2 nanotube clusters are coated with the composites of ultrafine MoO2 nanoparticles embedded in carbon matrix (TiO2@MoO2-C), and demonstrates the superior electrochemical performance as the anode material for SIBs. The ultrafine MoO2 nanoparticles and the unique nanorod structure of TiO2@MoO2-C help to decrease the Na+ diffusion length and to accommodate the accompanying volume expansion. The good integration of MoO2 nanoparticles into carbon matrix and the cable core role of TiO2 nanotube clusters enable the rapid electron transfer during discharge/charge process. Benefiting from these structure merits, the as-made TiO2@MoO2-C can deliver an excellent cycling stability up to 10 000 cycles even at a high current density of 10 A g(-1). Additionally, it exhibits superior rate capacities of 110 and 76 mA h g(-1) at high current densities of 10 and 20 A g(-1), respectively, which is mainly attributed to the high capacitance contribution.