Figure 9.

a) Schematic illustration of the fabrication of FeS₂@C porous nanooctahedra cathode: I) uniform coating of carbon‐rich polysaccharide (CP) layers onto FeS₂ octahedra; II) carbonization of CP layers and partdecomposition of inner encapsulated FeS₂; III) removing of acid soluble FeS originated from the decomposed FeS₂ by hydrochloric acid. b) Details of the discharge and charge processes of FeS₂@C porous nanooctahedra cathode in schematic illustration. c) Rate capability at different rates (increased from 0.5C to 5C); d) discharge energy density and energy efficiency of the FeS₂@C porous nanoctahedra vs.cycle number shown along with the theoretical discharge energy density of LiCoO₂ cathode (550 Wh kg^–1 based on the mass of LiCoO₂ only), which is calculated using an average voltage of 3.9 V and a capacity of 140 mAh g^–1. Reproduced with permission.148