Synthesis of amorphous cobalt silicate nanobelts@manganese silicate core-shell structures as enhanced electrode for high-performance hybrid supercapacitors.

Among diverse transition metal silicates (TMSs), cobalt silicate (Co2SiO4) and manganese silicate (MnSiO3) have been diffusely developed for electrode materials due to their high theoretical capacity, structural stability and simple synthetic process. In this work, Co2SiO4 nanobelts@MnSiO3 have been designed and synthesized as the enhanced electrode for high-performance hybrid supercapacitors. The one-dimensional (1D) Co2SiO4 nanobelts enhance their ability to transport electrons along the long axis, which allows current collection during the charge and discharge to improve electrochemical performances. The MnSiO3 coating can be a steady elastic buffer layer, which can protect the active materials during the charge and discharge in effect. What's more, the "core" and "shell" will both be a considerable offering to the total capacity. Sure enough, the capacitance value of Co2SiO4 nanobelts@MnSiO3 can achieve 309 F g-1 at 0.5 A g-1 accompanied by 64% capacitance retention after 10,000 cycles. And the hybrid supercapacitor (HSC) device assembled by Co2SiO4 nanobelts@MnSiO3 and activated carbon (AC) own an excellent capacitance of 384 mF cm-2 at 2 mA cm-2 accompanied by 57% capacitance retention after 2000 cycles. Meanwhile, the Co2SiO4 nanobelts@MnSiO3//AC HSC device's power density (P/W m-2) and energy density (E/Wh m-2) can reach to be 30 W m-2 and 0.77 Wh m-2, respectively. The unique and novel microstructure makes cobalt silicate and manganese silicate shine once again in excellent electrochemical performance.