Influence of carbon towards improved lithium storage properties of Li2MnSiO4 cathodes

Abstract

Superior lithium storage in Li₂MnSiO₄ cathodes was observed by altering carbon content during the formulation of electrodes. Initially, Li₂MnSiO₄ was prepared by a conventional solid-state reaction at 900 °C under Ar flow with a fixed amount of adipic acid, which acts as a gelating agent during synthesis. The phase formation was confirmed through powder X-ray diffraction measurements. Scanning electron microscope pictures indicate the particulate morphology of synthesized Li₂MnSiO₄ particles. Various compositions of electrodes were formulated using the conducting carbon (ketjen black) from 3 to 11 mg along with active material. All the fabricated electrodes were cycled in a Li/Li₂MnSiO₄ cell configuration to evaluate its lithium storage performance at 0.05 C rate. Among the electrodes, 42% carbon in the composite electrode exhibited a very stable discharge behaviour ∼140 mA h g⁻¹ for 40 cycles at room temperature. Such storage performance was ascribed to the improved electronic conductivity of Li₂MnSiO₄ electrodes by incorporating carbon. This improvement was supported by electrochemical impedance spectroscopy measurements. Rate performance studies were also conducted and presented in the manuscript.