Synthesis of carbon coated Bi2O3 nanocomposite anode for sodium-ion batteries

Bi2O3 is a promising sodium storage material due to its high gravimetric specific capacity. However, Bi2O3 possesses lower electrochemical performance due to its poor electrical conductivity and structural integrity during Na+ insertion/extraction process. Here, we prepared a carbon coated Bi2O3 nanocomposite by a redox reaction and a carbon coating process. In this nanocomposite, the carbon layer can avoid the direct contact between Bi2O3 and electrolyte, which inhibits the repeated formation and decomposition of solid electrolyte interface film. Additionally, the carbon layer can enhance the electrical conductivity of Bi2O3 and suppress its aggregation due to its volume change during charge and discharge process. In addition, nano-sized Bi2O3 can reduce the transport distance of Na+ and electron. The nanocomposite shows excellent cycling performance and rate capability as anode for sodium-ion batteries. A high capacity of 421 mAh g−1 can be maintained after 100 cycles at 1500 mA g−1 and 392 mAh g−1 can be shown at 3200 mAh g−1.