Ferrocene-Derived Sulfur-Rich Cathode for High-Performance Rechargeable Lithium Batteries

Owing to abundant resources and low cost, organic compounds as cathode materials have shown unique advantages in lithium batteries. Control of structures could open a new chapter in designing the advanced organic cathode materials. Herein, we first report the synthesis of the ferrocene sulfur-rich copolymer (Fc-S), where the ring opening polymerization of elemental sulfur takes place along the cyclopentenyl of ferrocene. The Fc-S copolymer exhibits the nanosphere in which there is covalent binding between Fc and sulfur through the chemical and physical effects. The Fc skeleton can accommodate the 70 wt % sulfur to form the Fc-S nanocages (Fc-70S), which can effectively relieve the huge volume change of sulfur during the charge/discharge process and ease dissolution and diffusion of polysulfides out of cathode. The Li/Fc-70S cell can display the initial discharge specific capacity of 1037.4 mAh g–1 and long cycle life for 700 cycles with the retention of 55.1% at 0.2 C. As a result, this novel Fc-S nanocomposite provides the approaches for the improvement of Li–S batteries and the development of advanced organic electrode materials.