Fluorine atom-inducing graphene oxide in situ coating SnPO composites as anode for sodium ion batteries

Abstract With the development of society, rechargeable batteries are becoming ever-popular in people's lives. Although rechargeable sodium-ion batteries have attracted a large number of researchers, they suffer from the limited cycle stability and low capacity. To address these issues, tin-phosphorus-oxygen (SnPO) composite materials were protected by the curling of reduced graphene oxide (rGO) induced by the fluorine atoms from the electrolyte. The in-situ coating protection not only can increase the electrical conductivity, but also more importantly adjust the large volume expansion and suppress the pulverization of electrode materials during cycling. As a result, the SnPO composite delivers an initial discharge/charge capacity of 843 mAh g −1 /450 mAh g −1 at the current density of 50 mA g −1 and still retains a reversible discharge capacity of ∼420 mAh g −1 after 100 cycles. Moreover, it achieves a superior rate performance with the capacity of 200 mAh g −1 at the current density of 2000 mA g −1 . The superior electrochemical performance and the facile in-situ protection strategy will make a great contribution to the future development of rechargeable batteries.