Three-dimensional cage-like Si@ZIF-67 core-shell composites for high-performance lithium storage

Abstract

Silicon is considered to be a desirable LIBs electrode material because of its high specific capacity and suitable reaction voltage. However, its large volume expansion effect severely limits its commercial application. Therefore, surface modification and smart structural designs, such as nanostructures, core-shell structures and silicon-carbon composite structures, are some of the most effective ways to solve the serious volume expansion effect of silicon anode materials. In recent years, metal oxide anode materials derived from organic frameworks have been extensively studied. They have porous structures and abundant carbon materials, which can effectively enhance conductivity and alleviate the volume expansion. In this paper, Si@ZIF-67 composites were successfully prepared by a simple liquid phase method. When this composites had been reduced at 600 °C and been used as an anode material in a lithium-ion battery, it delivers a high specific capacity of 1230 mA h g−1 after 200 cycles at 0.5 A g−1. Even at a high current density of 1 A g−1 for 400 cycles, it still maintains a specific capacity of 1180 mA h g−1, indicating excellent electrochemical performance. The surface modification results of this paper provide a new way to solve the volume expansion effect of a silicon anode material.