Sb₂Te₃ Hexagonal Nanosheets as High-Capacity Positive Materials for Rechargeable Aluminum Batteries

Among all metal-ion batteries, aluminum-ion ones are more advantageous because of a longer cycle life, less safety concerns, and lower cost, which has become an ideal alternative to the next-generation lithium battery systems. However, the poor stability of the positive material, the strong acidity of the electrolyte, and the high price of the current collector restrict the wide use of aluminum-ion batteries (AIBs). Compared with semiconductors, Sb2Te3 has higher conductivity and faster electron transport capabilities, which can significantly reduce the obstacles to energy accumulation. In this study, the Sb2Te3 nanosheets deliver a high specific capacity of ∼375 mA h g–1 at the first cycle and a discharge plateau ∼1.3 V at 500 mA g–1. In addition, through applying an improved separator, the dissolution of the positive material was slowed down and the electrochemical performance of Sb2Te3 was enhanced. Therefore, the reversible capacity of Sb2Te3 can be retained at about 110 mA h g–1 beyond 500 cycles. By density functional theory calculations, the valence change of Sb2Te3 in the reaction can be analyzed. This confirms that the reaction of SbCl3 with the changed valence of Te is more likely to occur, and the valence of Sb in Sb2Te3 can remain unchanged. The results demonstrate the feasibility of telluride application as positive electrodes in AIBs.