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

For the applications of aqueous Li-ion hybrid capacitors and Na-ion hybrid capacitors,potassium ions are pre-inserted into MnO2tunnel structure,the as-prepared K1.04Mn8O16materials 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-8 A) as anode and K1.04Mn8O16as cathode.It shows high energy and power densities.Li-ion capacitors reach a high energy density of 127.61 Wh kg-1at the power density of 99.86 W kg-1and 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.