FeSO_4 as a Novel Li-Ion Battery Cathode

FeSO_4 has the characteristics of low cost and theoretical high energy density (799 W\cdoth\cdotkg^-1 with a two-electron reaction), which can meet the demand for next-generation lithium-ion batteries. Herein, FeSO_4 as a novel high-performance conversion-reaction type cathode is investigated. We use dopamine as a carbon coating source to increase its electronic conductivity. FeSO_4@C demonstrates a high reversible specific capacity (512 mA\cdoth\cdotg^-1) and a superior cycling performance (482 mA\cdoth\cdotg^-1 after 250 cycles). In addition, we further study its reaction mechanism. The FeSO_4 is converted to Fe and Li_2SO_4 during lithium ion insertion and the Fe|Li_2SO_4 grain boundaries further store additional lithium ions. Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes.