Lightweight Metallic MgB2 Mediates Polysulfide Redox and Promises High-Energy-Density Lithium-Sulfur Batteries

？ Li-S battery cathode host based on metallic, lightweight, high-surface-area MgB2 ？ First-principles calculations reveal unique binding of sulfides with boride surface ？ Surface-mediated polysulfide redox yields a high exchange current at interface ？ Stable cycling at high sulfur loadings of 9.3 mg cm？2 with low electrolyte volum