High capacity and fast Na+ transport in the SbPS4 material by Bi3+ substitution for sodium-ion batteries

Abstract

The SbPS₄ material has become a research hotspot in sodium ion battery anode due to its high specific capacity. Herein, we propose an effective strategy of Bi³⁺ substitution in SbPS₄ to improve the electrochemical performance during long-term charge and discharge processes. Compared with the specific capacity of 574 mA h g⁻¹ of SbPS₄, the Sb_0.7Bi_0.3PS₄ material delivers a higher value of 831 mA h g⁻¹ at 0.1 A g⁻¹, which is a 30.9% improvement. The improvement in the electrochemical performance was attributed to the introduction of Bi active element, which can reduce large volume changes and enhance the ion and electron conductivities of SbPS₄. In addition, we have proved that pseudo-capacitance control in kinetic behaviors is instrumental for fast Na⁺ transport in Sb_0.7Bi_0.3PS₄ (92.1% of the total capacity comes from the capacitive contribution at 1.0 mV s⁻¹). Moreover, the full battery exhibited excellent rate performance (122.9 mA h g⁻¹ at 0.1C and 102.7 mA h g⁻¹ at 1C) when paired by a Sb_0.7Bi_0.3PS₄ anode and a Na₃V₂(PO₄)₂O₂F cathode.