Carbon-Encapsulated Pyrite as Stable and Earth-Abundant High Energy Cathode Material for Rechargeable Lithium Batteries

Cathode materials consisting of porous pyrite nano‐octahedra encapsulated by uniform carbon nanocages exhibit very high energy density, superior rate capability (reversible capabilities of 439, 340, and 256 mA h g−1 at 1C, 2.5C, and 5C, respectively) and stable cycling performance (ca. 10% capacity loss after 50 cycles at 0.5C with a capacity retention of 495 mA h g−1).