Energy storage performance of hybrid aqueous supercapacitor based on nano-Li2MnSiO4 and activated carbon

Novel asymmetric supercapacitor (ASC) composed of nanocrystalline Li2MnSiO4 (LMS) and activated carbon (AC) in aqueous electrolyte is investigated. ASC is tested in three different electrolytes, viz. 2 M KOH, 2 M LiOH, and 2MLi(2)SO(4). The aqueous solution of 2 M KOH is found to be an appropriate electrolyte in terms of better capacitance, cyclability, and rate capability probably due to a smaller hydration sphere radius and larger ionic conductivity of K+ ions. The electrochemical performance of ASC is examined using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) cycling, and results are complimented with electrochemical impedance spectroscopy (EIS). Novel ASC exhibits the specific capacitance of 60 (similar to 5) F g(-1) at 3 mV s(-1) in 2 M KOH. The excellent cyclability (till 5000 cycles) is also observed. The improved supercapacitive properties are mainly ascribed to the unique morphology of LMS (surface area similar to 30 m(2) g(-1) and homogenous meso-pore distribution) which provides easy percolation of electrolytic ions to provide better formation of electric double layer with minor redox behavior. The ex situ X-ray diffraction (XRD) measurement was carried out on a cycled electrode to support the plausible reaction mechanism.