Unlocking High-Voltage Sodium Ion Batteries with MOF-Derived Cr2S3@C Anode Materials

Abstract

Extensive research on transition metal sulfide (TMS) materials highlight their potential as promising anode materials for sodium-ion batteries (SIBs). However, most TMS anodes exhibit average reaction potentials above 1.5 V vs. Na+/Na, resulting in full cell discharge plateaus below 2 V. Clearly, the inherently high reaction potentials associated with conversion reactions present a challenge in achieving high-voltage full cells. This not only significantly constrains the energy density utilization but also narrows the application scenarios for the final full cells. In this study, we present a cutting-edge MOF-derived Cr2S3@C composite as a promising anode material for SIBs, featuring a dual-mechanism charge storage process encompassing both conversion and alloying reactions. Remarkably, the conversion reactions occur at low potential plateau and, in conjunction with alloying reactions, offer considerable promise for developing high-voltage full cells. The developed anode material exhibits an outstanding reversible specific capacity of 764 mAh g–1, achieving a substantial energy density of 206 Wh kg–1 at a cut-off voltage of 4.0 V when paired with a Na3V2(PO4)3 cathode. This study provides new insights into the rational selection of TMS anodes for SIBs and demonstrates the utility of Nernst-based theoretical screening for guiding nanocomposite anode design.