An Integrated Na2S−Electrocatalyst Nanostructured Cathode for Sodium–Sulfur Batteries at Room Temperature

Room-temperature sodium–sulfur (RT Na–S) batteries offer a superior, high-energy-density solution for rechargeable batteries using earth-abundant materials. However, conventional RT Na–S batteries typically use sulfur as the cathode, which suffers from severe volume expansion and requires pairing with a sodium metal anode, raising significant safety concerns. Utilizing Na2S as the cathode material addresses these issues, yet challenges such as Na2S’s low conductivity as well as the shuttle effect of polysulfide still hinder RT Na–S battery development. Herein, we present a simple and cost-effective method to fabricate a Na2S–Na6CoS4/Co@C cathode, wherein Na2S nanoparticles are embedded in a conductive carbon matrix and coupled with dual catalysts, Na6CoS4 and Co, generated via the in situ carbothermal reduction of Na2SO4 and CoSO4. This approach creates a three-dimensional porous composite cathode structure that facilitates electrolyte infiltration and forms a continuous conductive network for efficient electron transport. The in situ formed Na6CoS4/Co electrocatalysts, tightly integrated with Na2S, exhibit strong catalytic activity and robust physicochemical stabilization, thereby accelerating redox kinetics and mitigating the polysulfide shuttle effect. As a result, the Na2S–Na6CoS4/Co@C cathode achieves superior capacity retention, demonstrating a discharge capacity of 346 mAh g−1 after 100 cycles. This work highlights an effective strategy for enhancing Na2S cathodes with embedded catalysts, leading to enhanced reaction kinetics and superior cycling stability.