Simultaneously Porous Structure and Chemical Anchor: A Multifunctional Composite by One-Step Mechanochemical Strategy toward High-Performance and Safe Lithium–Sulfur Battery

A lithium–sulfur (Li–S) battery has been regarded as one of the most promising energy-storage systems to meet requirements for high energy density in electric vehicles, advanced portable electronic devices, and so on. However, practical application of a Li–S battery is restricted severely by easy dissolution of lithium polysulfides and high flammability of sulfur. Herein, we developed, for the first time, a multifunctional composite directly prepared by a facile, green, low-cost, and large-scale ball-milling method with fly ash and sulfur. Due to the unique microstructure and sulfur-related components as chemical anchors, composites possessed good electron/ion transport, favorable resistance to volume change of sulfur, and strong chemical affinity to polysulfides, which greatly facilitate redox kinetics, maintain structural integrity of the cathode, and suppress polysulfide shuttling in electrolyte, hence significantly boosting electrochemical performance of the Li–S battery with high initial discharge capacity, superior cycling stability, and satisfying rate capability. Typically, Li–S batteries based on a composite with a sulfur loading of 86.9% present initial discharge capacities of 969.8, 894.3, and 769.7 mAh g–1 as well as capacity decay rates of 0.068% (400 cycles), 0.1% and 0.042% per cycle (200 cycles) at 0.2, 0.5, and 1 C, respectively. Moreover, the average specific self-extinguishing time of the composite-based cathode was clearly reduced to less than half of that of the pristine sulfur-based cathode, indicating significantly promoting the safety of the battery.