Recent advances in effective protection of sodium metal anode

Because of the ultrahigh theoretical capacity, sodium metal is regarded as the most prospective next-generation anode material. However, due to the dendritic sodium formation as well as high chemical reactivity with electrolyte, it still has safety issues and poor cyclability, which have severely impeded the practicability of sodium metal technology. Therefore, it is important for the advanced sodium metal batteries to construct the stable dendrite-free sodium metal anode. In recent years, considerable efforts have been directed towards solving these problems, including sodium-electrode framework design, organic electrolyte modification, sodium-metal interface protection. Furthermore, solid-state electrolytes have an advantage over the liquid electrolytes and are considered to constitute safe solid sodium metal batteries so as to prohibit problematic sodium dendrites. This review comprehensively analyzes the growth mechanism of the sodium dendrites and summarizes recent advances in the strategies of suppressing the formation of sodium dendrite. The practical application in full batteries and future challenges of sodium metal anode are addressed for energy storage devices. We hope this review delivers an overall picture of sodium protection strategies and inspires more researches in the future.