Electrochemical performance of carbon-coated lithium manganese silicate for asymmetric hybrid supercapacitors

Nanoscale carbon-coated Li 2MnSiO 4 powder is prepared using a conventional solid-state method and can be used as the negative electrode in a Li 2MnSiO 4/activated carbon (AC) hybrid supercapacitor. Carbon-coated Li 2MnSiO 4 material presents a well-developed orthorhombic crystal structure with a P mn2 1 space group, although there is a small impurity of MnO. The maximum specific capacitance of the Li 2MnSiO 4/AC hybrid supercapacitor is 43.2 F g −1 at 1 mA cm −2 current density. The cell delivers a specific energy as high as 54 Wh kg −1 at a specific power of 150 W kg −1 and also exhibits an excellent cycle performance with more than 99% columbic efficiency and the maintenance of 85% of its initial capacitance after 1000 cycles.