Solid‐Electrolyte Interphase Formation in Nanocarbon Composite Lithium‐Ion Battery Anodes

Abstract

Carbon nanotubes (CNTs) have emerged as a promising conducting additive for next‐generation high‐capacity anode materials owing to their ability to form an electrically conductive network that maintains contact when subjected to significant volume expansion. However, as a result of their high porosity and surface area, CNTs currently suffer from poor initial irreversible capacity loss due to solid‐electrolyte interphase (SEI) formation and excessive electrolyte consumption. Currently, there is limited understanding about how and where SEI forms on CNT‐containing electrodes. In this work, electrochemical atomic force microscopy (EC‐AFM) is employed to directly observe the influence of CNTs on SEI formation. By varying graphite:CNT ratio in casted electrodes, it is demonstrated that increasing CNT content results in earlier onset formation and a greater quantity of SEI. In addition, it is found that the SEI structure and nucleation behavior change with varying CNT concentration which has direct implications on the electrochemistry. Operando EC‐AFM provides real‐time visual insights into the SEI behavior which is critical for providing a more holistic understanding of the SEI formation. This work therefore helps redefine the role CNTs play within next‐generation anode materials and the impact they have on SEI dynamics.