Progress and innovation of nanostructured sulfur cathodes and metal-free anodes for room-temperature Na–S batteries

Rechargeable batteries are a major element in the transition to renewable energie systems, but the current lithium-ion battery technology may face limitations in the future concerning the availability of raw materials and socio-economic insecurities. Sodium-sulfur (Na-S) batteries are a promising alternative energy storage device for small- to large-scale applications driven by more favorable environmental and economic perspectives. However, scientific and technological problems are still hindering a commercial breakthrough of these batteries. This review discusses strategies to remedy some of the current drawbacks such as the polysulfide shuttle effect, catastrophic volume expansion, Na dendrite growth, and slow reaction kinetics by nanostructuring both the sulfur cathode and the Na anode. Moreover, a survey of recent patents on room temperature (RT) Na-S batteries revealed that nanostructured sulfur and sodium electrodes are still in the minority, which suggests that much investigation and innovation is needed until RT Na-S batteries can be commercialized.