Na₂S Cathodes Enabling Safety Room Temperature Sodium Sulfur Batteries

Room temperature sodium-sulfur (RT-Na/S) battery is regarded as a promising next-generation battery system because of their high theoretical specific capacity, and abundant availability of anodes and cathodes. Nevertheless, the direct use of sodium metal could result in the dendrite growth, causing the safety concerns. Interestingly, employing Na2S as the cathode materials can be paired with Na-free anode to effectively avoid the problem of dendrite growth. However, the poor electronic conductivity of Na2S and the sluggish kinetic conversion to sodium polysulfides can lead to high initial charge activation barriers and rapid capacity degradation, thereby constraining their practical application. In this concept, the electrochemical mechanism of Na2S cathode is summarized to present the potential for RT-Na/S batteries. Additionally, recent advances on Na2S cathodes have been discussed in detail with an emphasis on functionalized matrix, morphology modulation, and optimizing cell structure. Finally, the future opportunities and challenges for the development of Na2S cathode based RT-Na/S batteries are proposed.