Nano-Sized Bi2Te3@Reduced graphene oxide for enhanced sodium-ion storage: Insight into the electrochemical mechanism through in situ analysis

The development of new anode materials that meet the electrochemical performance requirements for sodium-ion batteries is critical but still significantly challenging. In this study, we synthesized a composite of ultrathin Bi2Te3 nanoparticles and reduced graphene oxide (Bi2Te3@rGO) through an in situ solvothermal reaction. This method enables Bi2Te3 nanoparticles to grow uniformly on the rGO surface, enhancing the electron-transfer rate and providing an excellent barrier against unfavorable reactions during the charging–discharging processes. The sodium-ion storage mechanism of Bi2Te3@rGO was investigated through in situ X-ray diffraction analysis. Bi2Te3@rGO was found to demonstrate high sodium-ion storage capacities of 456 mAh/g at 0.1 A/g and 272 mAh/g at a high current density of 5 A/g. This performance improvement is attributed to the contribution of rGO to suppressing the dissolution of polytellurides formed during the Na–Te reaction and the suppression of aggregation and subsequent inactivation of Bi or Te during the charging–discharging process, as revealed by post-cycling in situ and ex situ analyses. These findings offer insights into the sodium-ion storage mechanism of Bi2Te3 and highlight the integration of rGO as a promising strategy for enhancing the electrochemical properties of Bi2Te3.