Multilayer Porous Vanadium Nitride Microsheets Anodes for Highly Stable Na-ion Batteries

Sodiumion batteries(SIBs) have attracted intensive attention as promising alternative to lithium-ionbatteries(LIBs) for large scale energy storage systems because of low cost of sodium, similar energy storage mechanism and the reasonable performance. However, it is still a great challenge to search and design a robust structure of anode materials with excellent cycling stability and high rate capability for SIBs. Herein, multilayer porous vanadium nitride (VN) microsheets are synthesized through a facile and scalable hydrothermal synthesis-nitrogenization strategy as an effective anode material for SIBs. The multilayer porous VN microsheets not only offer more active sites for fast Na+ insertion/extraction process and short diffusion pathway, but also effectively buffer the volume change of anode due to more space in the multilayer porous structure. The large proportions of capacitive behavior imply that the Na+ charge storage depends on the intercalation pseudocapacitive mechanism. The multilayer porous VN microsheets electrodes manifest excellent cycling stability and rate capability, delivering a discharge capacity of 156.1 mA·h/g at 200 mA/g after 100 cycles, and a discharge capacity of 111.9 mA·h/g at 1.0 A/g even after 2300 cycles with the Coulombic efficiency of nearly 100%.