Recent progress of advanced carbon-based cathode in sodium-selenium batteries

In sodium chalcogen batteries, selenium has attracted greater attention in Na-Se batteries due to its attractive theoretical capacity and conductivity which is 20 orders of magnitude higher than that of sulfur. However, the capacity of the battery suffers from the shuttle effect, which limits its further enhancement. Therefore, the design of C/Se composite cathode that can alleviate volume expansion, accelerate electron transport, and inhibit polyselenide dissolution by using carbon matrix as selenium host has become a hot topic of extensive research nowadays. This paper makes a comprehensive review of C/Se composite as the cathode of Na-Se battery, distinguishing and highlighting different carbon matrices from the perspectives of hierarchical porous structure and adsorption effect, providing valuable insights into the rational design of carbon hosts and the analysis of operating principle. The research on Na-Se batteries is still in a relatively primary stage, and this work is expected to stimulate more visionary ideas.