Single-crystalline Mn2V2O7 anodes with high rate and ultra-stable capability for sodium-ion batteries

Abstract

The abundant sodium resources provide a great potential for the practical application of sodium ion batteries (SIBs). However, the development of feasible anode materials with high-rate capability to solve the slow diffusion kinetics of Na+ has always been a major challenge for high performance SIBs. Herein, a layer-structured metal vanadate Mn2V2O7 (MnVO) with large open channel within its crystal structure frame is for the first time identified as a promising candidate for high-rate SIB anodes, which ensures a large pseudocapacitance contribution. Moreover, the prepared micron size single crystal structure of MnVO effectively shortens the diffusion and transmission paths of Na+ ions and electrons, thus accomplishing high capacity (a reversible capacity of 250 mA h g−1 at 0.2 A g−1), excellent cycling stability (125 mA h g−1 at 10 A g−1 after 3500 cycles with 98% capacity retention) and fast charge and discharge rates (120 mA h g−1 at 20 A g−1 after 5000 cycles). This work explores transition metal vanadates as SIB anodes with excellent rate performance.