Limited resources of lithium mean that lithium-based batteries will not be able to meet increasing energy-storage demands. Consequently, the price of Li is expected to skyrocket. Room-temperature sodium–sulfur (RT-Na/S) batteries are a promising alternative due to resource abundance (of both sodium and sulfur), non-toxicity, low cost and the high theoretical capacity of sulfur (1672 mAh g–1). But, the dissolution of polysulfides into the electrolyte during cycling causes a low reversible capacity and fast capacity fade. Now, researchers led by Shi-Zhang Qiao at the University of Adelaide have designed a new class of sulfur hosts for RT-Na/S batteries: nanometre-sized transition metal clusters decorated on hollow carbon nanospheres. These clusters are able to assist the immobilisation of sulfur and enhance the conductivity and activity of sulfur (Zhang B.-W., Sheng T., Wang Y.-X., Chou S., Davey K., Dou S.-X., Qiao S.Z. Angew. Chem. Int. Ed. 2019, 58, 1484–8). They serve as electrocatalysts to quickly reduce polysulfides into short-chain sulfides, thus improving the electrochemical performance of RT-Na/S batteries. Among these sulfur hosts, iron-based clusters exhibited excellent cycling and rate performance for RT-Na/S batteries.