Cost effective urea combustion derived mesoporous-Li2MnSiO4 as a novel material for supercapacitors

Abstract

Mesoporous-Li₂MnSiO₄ (LMS) having a surface area of 35 (±2) m² g⁻¹ is produced using a very simple, fast and cost effective urea combustion method for the first time and characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and surface area analysis. Li₂MnSiO₄ is crystallized in the orthorhombic phase with space group – Pmn2₁. The lattice parameters: a = 6.317(10) Å, b = 5.385(9) Å, c = 4.988(8) Å are calculated by the Rietveld method. The urea combustion derived LMS is found to be thermally stable till 600 °C in air and thereafter disintegrates into Li₂SiO₃ (orthorhombic) and MnO₂ (cubic). The presence of a homogeneous mesoporous (<20 nm) framework with a high surface area shows orthorhombic Li₂MnSiO₄ to be promising as a novel supercapacitor electrode as it delivers a specific capacitance of 175 (±5) F g⁻¹ at 3 mV s⁻¹ in 2 M KOH solution. The supercapacitive performance was further examined by galvanostatic charge–discharge cycling and complimented by electrochemical impedance spectroscopy.