Electronic structure and electrochemical performance of CoS2/MoS2 nanosheet composite: Simulation calculation and experimental investigation.

Conductive CoS 2 and cycling stable MoS 2 are integrated to form the interconnected CoS 2 /MoS 2 nanosheet composite with electroactive interface grown on Mo foil substrate to act as high-performance supercapacitor anode material with electrochemical and mechanical stability. The band gap and density of state of CoS 2 /MoS 2 determined by density functional theory simulation calculation indicates its improved electrical conductivity. The interface binding energy and differential charge density reveal that strong crystal interface interaction between MoS 2 (002) and CoS 2 (111) enables effective charge transfer in interconnected CoS 2 /MoS 2 nanosheet composite. CoS 2 /MoS 2 exhibits higher specific capacitance of 605.77 mF cm−2 than MoS 2 of 218.1 mF cm−2 at 1.0 mA cm−2 in 0.5 M Na 2 SO 4. The rate capacitance retention is improved from 57.8% of MoS 2 to 82.8% of CoS 2 /MoS 2 at 1–10 mA cm−2. The high cycling stability is achieved for MoS 2 (100.2%) and CoS 2 /MoS 2 (104.05%) after 5000 cycles at 10 mA cm−2 due to self-activation of multilayered MoS 2. An asymmetric solid-state supercapacitor using CoS 2 /MoS 2 anode and MnO 2 /carbon paper cathode achieves a capacitance of 4.32 F cm−3 at 1.0 mA cm−2 and an energy density of 1.944 mWh cm−3 at a power density of 18 mW cm−3, 97.8% after 5000 cycles at 5.0 mA cm−2, presenting effective energy storage. [ABSTRACT FROM AUTHOR]