Cathodes comprising Li2MnSiO4 nanoparticles dispersed in the mesoporous carbon frameworks, CMK-3 and CMK-8

Abstract

Nanocrystals of lithium manganese silicate were loaded and dispersed within the frameworks of CMK-3 and CMK-8 mesoporous carbons. TEM observations suggest that the particles grow at a certain level of loading. The adsorption of nitrogen implies that the framework gradually becomes filled with oxide, though a considerable volume of mesopore still remains even when particles are found outside the pores by TEM. The clogging of the mesopores by Li2MnSiO4 oxide is discussed, which is important in understanding the diffusion of Li+. The charge and discharge reactions of Li+ were investigated. When the loading is low, the charge–discharge curves are considerably different between these two mesoporous carbon frameworks, though the plateaux and their smearing tendency with cycle number are quite similar. The contribution of carbon to this reaction is calculated, considering the symmetry of CMK-3, and subtracted from the charge–discharge curves of the composite material. The “net” charge–discharge curves of Li2MnSiO4 nanoparticles indicate a capacity of 300–360mAh/g for Li2MnSiO4@CMK-3, which is close to the theoretical capacity for the reaction with two Li+ ions per unit formula, 330mAh/g.