Core cation tuned MxCo3-xS4@NiMoS4 [M = Ni, Mn, zn] core–shell nanomaterials as advanced all solid-state asymmetric supercapacitor electrodes

A supercapacitor would be one of the most reliable energy storage device, but due to inadequate energy density, it is restricted to commercialization. The bimetallic core nanoparticles possess multiple oxidation states in their [email protected] design, and understanding the effect of tuning of core cations are noble artifacts for effective research. Here, an effective strategy of varying the cations (M = Ni, Zn and Mn) in the MxCo3-xS4@NiMoS4 [email protected] is demonstrated. Among the MxCo3-xS4@NiMoS4 electrodes, the NiCo2S4@NiMoS4 [email protected] showed better electrochemical storage properties with areal capacity/gravimetric capacity of 0.92 mAh cm−2/287.5 mAh g−1 at 3 mA cm−2 (3410.0 F g−1 capacitance), and superior cycle life with ca. 92.3% capacity retention at high current density of 50.0 mA cm−2 after 10,000 cycles. Moreover, real–time application was monitored by assembling an asymmetric solid–state device, taking NiCo2S4@NiMoS4 as the cathode and Fe2O3/NG hydrogel as the anode. The device delivers an excellent cell capacity of 90.4 mA hg−1 with a remarkable cycle life of 90.5% after 10,000 cycles. The device stored a very high energy density of 72.3 Wh kg–1at 460.0 W kg−1 and retained an energy density of 32.6 Wh kg−1 at a high power density of 11,844.0 W kg−1, demonstrating high applicability towards practical energy storage devices.