Ultrathin Na_1.1V₃O_7.9 Nanobelts with Superior Performance as Cathode Materials for Lithium-Ion Batteries

The Na_1.1V₃O_7.9 nanobelts have been synthesized by a facile and scalable hydrothermal reaction with subsequent calcinations. The morphologies and the crystallinity of the nanobelts are largely determined by the calcination temperatures. Ultrathin nanobelts with a thickness around 20 nm can be obtained, and the TEM reveals that the nanobelts are composed of many stacked thinner belts. When evaluated as a cathode material for lithium batteries, the Na_1.1V₃O_7.9 nanobelts exhibit high specific capacity, good rate capability, and superior long-term cyclic stability. A high specific capacity of 204 mA h g^–1 can be delivered at the current density of 100 mA g^–1. It shows excellent capacity retention of 95% after 200 cycles at the current density of 1500 mA g^–1. As demonstrated by the ex situ XRD results, the Na_1.1V₃O_7.9 nanobelts have very good structural stability upon cycling. The superior electrochemical performances can be attributed to the ultra-thin nanobelts and the good structural stability of the Na_1.1V₃O_7.9 nanobelts.