Potassium pre-inserted K1.04Mn8O16 as cathode materials for aqueous Li-ion and Na-ion hybrid capacitors

Abstract For the applications of aqueous Li-ion hybrid capacitors and Na-ion hybrid capacitors, potassium ions are pre-inserted into MnO2 tunnel structure, the as-prepared K1.04Mn8O16 materials consist of nanoparticles and nanorods were prepared by facile high-temperature solid-state reaction. The as-prepared materials were well studied and they show outstanding electrochemical behavior. We assembled hybrid supercapacitors with commercial activated carbon (YEC-8A) as anode and K1.04Mn8O16 as cathode. It shows high energy and power densities. Li-ion capacitors reach a high energy density of 127.61 Wh kg−1 at the power density of 99.86 W kg−1 and Na-ion capacitor obtains 170.96 Wh kg−1 at 133.79 W kg−1. In addition, the hybrid supercapacitors demonstrate excellent cycling performance which maintain 97% capacitance retention for Li-ion capacitor and 85% for Na-ion capacitor after 10,000 cycles.