Spatially Uniform Lithiation Enabled by Single-Walled Carbon Nanotubes

Abstract

Uncontrolled volumechanges in Si-based anode materials drasticallydeteriorate the electron-conduction network, accelerating the capacityfading. From a macroscopic viewpoint, the use of single-walled carbonnanotubes (SWCNTs) as conductive additives has been confirmed tohelp preserve electron-conduction channels. However, the specificmechanism of how SWCNTs behave in Si-based anodes remains unclear.Herein, we investigate the role of SWCNTs in the pulverization behaviorof Si-based anode materials at the nanoscale. Surface potential mappingusing Kelvin probe force microscopy showed an uneven charging/dischargingprocess of the Si-based anode in the absence of SWCNT additives. Conversely,the anode including SWCNTs enabled uniform electron transfer to theactive material, providing a stable electrochemical reaction site.Our visualization method reveals the role of SWCNTs in ensuring uniformvolume change during cycling and ultimately alleviation of particlepulverization.