Hierarchical CaMn2O4/C Network Framework toward Aqueous Zn Ion Hybrid Capacitors as Competitive Cathodes

Manganese-based materials have received more attention as cathodes for aqueous zinc ion hybrid capacitors (AZIHCs) due to their advantages such as abundant reserves, low cost, and large theoretical capacity. However, manganese-based materials have the disadvantage of poor electrical conductivity. Herein, a solid-phase method was used to synthesize a hierarchical carbon-coated calcium manganate (CaMn2O4/C) network framework as the cathode for AZIHCs. Thanks to the unique structural/componential merits including conductive carbon coating and hierarchical porous architecture, the achieved CaMn2O4/C cathode shows an exceptionally long life of close to 5000 cycles at 2.0 A g−1, with a reversible specific capacity of 195.6 mAh g−1. The assembled CaMn2O4/C-based AZIHCs also display excellent cycling stability with a capacity retention rate of 84.9% after 8000 cycles at 1.0 A g−1, and an energy density of 21.3 Wh kg−1 at an output power density of 180.0 W kg−1.