Polyanions Enhance Conversion Reactions for Lithium/Sodium-Ion Batteries: The Case of SbVO4 Nanoparticles on Reduced Graphene Oxide

Anode materials based on redox alloying/dealloying reactions are regarded as one of the promising electrodes in Li/Na-ion batteries. However, the enormous volume change upon cycling induces the giant structure strain, particle pulverization and then capacity decay. Here, vanadates are proposed to mitigate this concern for alloy-type anode materials, using SbVO4 as an example. As indicated by density function theory and in situ/ex situ techniques, VO43- enhances the conversion reaction between Sb3+ and Sb, buffers the structure change induced by alloying/dealloying reactions of Sb and exhibits the electrochemical activity to Li ions. These results make SbVO4 superior to Sb, Sb2O3 and SbPO4 in the electrochemical performances, which applies both to lithium-ion batteries and to sodium-ion batteries. Then, the structure design and carbon composite are achieved by depositing monodispersed SbVO4 nanocrystals on reduced graphene oxides via a simple solvothermal reaction. This composite shows a good cycling stability and a high rate capability, especially in sodium-ion batteries (73.6% after 1500 cycles at 1 A g(-1), or 252 mAh g(-1) at 10 A g(-1)). These results open the door for other alloy-type anode materials to improve the performances.