Carbon-coated CoP3 nanocomposites as anode materials for high-performance sodium-ion batteries

Abstract

It still remains a great challenge to develop a high-performance anode for sodium ion batteries. In this work, carbon-coated CoP3(CoP3@C) nanocomposites have been obtained by a high energy mechanical milling and used as an anode of sodium ion battery for the first time, showing a larger discharge capacity, longer cycling life and better rate capability as compared to plain CoP3. The superior performance is not only originated from significantly enhanced diffusion kinetics associating with the improvement of electron conductivity and volume change based on the presence of carbon layer, but also attributed to the partially pseudocapacitive behaviors of the redox reaction to construct a rapid electron transport pathway. In addition, the XRD and TEM analysis reveal that the Na-storage mechanism of the CoP3@C anode involves a conversion reaction from CoP3 to Na3P and metallic Co at the initial discharge and charge state. This study also provides a significant strategy to design special hybrid materials with excellent sodium storage capability for meeting the demand of large-scale energy storage systems.