Silicon particles coated with a metal–organic framework as anodes for enhanced lithium-ion batteries

Abstract

Silicon anodes are widely used in advanced energy conversion and storage devices such as lithium-ion batteries due to their high specific capacity. Nevertheless, the volume expansion and the poor electrical conductivity of silicon anodes limit their further commercial application. Thus, many researchers have recently explored several effective methods to improve their electrochemical performance and reduce volume expansion. These valuable methods include structure modification and design, seeking suitable binders, synthesizing composites of silicon with other materials, etc. In this work, we report a simple physical mixing method followed by pyrolysis to synthesize a Si and ZnMOF composite material (Si/ZnMOF) as a new type of MOF coated Si anode for lithium-ion batteries. Our Si/ZnMOF material pyrolyzed at 300 °C shows an excellent and stable capacity after long-term charge/discharge cycling. The specific capacity of the Si/ZnMOF-300 anode is 666.7 mA h g⁻¹ at a current density of 100 mA g⁻¹ after 250 charge/discharge cycles, which is twice as high as that of pure Si under the same charge/discharge conditions. The enhanced electrochemical performance of the Si/ZnMOF anode is due to the consolidated MOF network which covers the Si particle surface as a coating. That coating can alleviate the volume expansion of anode materials during the charge/discharge process.