Spatially Uniform Lithiation Enabled by Single-Walled Carbon Nanotubes

Uncontrolled volume changes in Si-based anode materials drastically deteriorate the electron-conduction network, accelerating the capacity fading. From a macroscopic viewpoint, the use of single-walled carbon nanotubes (SWCNTs) as conductive additives has been confirmed to help preserve electron-conduction channels. However, the specific mechanism of how SWCNTs behave in Si-based anodes remains unclear. Herein, we investigate the role of SWCNTs in the pulverization behavior of Si-based anode materials at the nanoscale. Surface potential mapping using Kelvin probe force microscopy showed an uneven charging/discharging process of the Si-based anode in the absence of SWCNT additives. Conversely, the anode including SWCNTs enabled uniform electron transfer to the active material, providing a stable electrochemical reaction site. Our visualization method reveals the role of SWCNTs in ensuring uniform volume change during cycling and ultimately alleviation of particle pulverization.