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

Nanoscale carbon-coated Li2MnSiO4 powder is prepared using a conventional solid-state method and can be used as the negative electrode in a Li2MnSiO4/activated carbon (AC) hybrid supercapacitor. Carbon-coated Li2MnSiO4 material presents a well-developed orthorhombic crystal structure with a Pmn2(1) space group, although there is a small impurity of MnO. The maximum specific capacitance of the Li2MnSiO4/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. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.