Integrated Contact and Chemical Prelithiation Method to Boost Coulombic Efficiency of Si-Based Anodes for Li-Ion Batteries

Abstract

Silicon-based anodes are considered a promising alternative for next-generation lithium-ion batteries (LIBs) due to their high theoretical capacity, which is significantly greater than that of traditional graphite anodes. However, the inherent challenge of the associated low initial Coulombic efficiency (ICE) due to irreversible lithium consumption limits their practical applications. Prelithiation techniques have emerged as a solution to compensate for this initial lithium loss, but current methods often face challenges such as high costs, incomplete lithiation, and complex setups. In this study, we present a novel modified direct contact prelithiation method utilizing a Li-ion-free biphenyl solution. This innovative approach integrates the advantages of both direct contact and wet chemical prelithiation, achieving fast, uniform, and cost-effective prelithiation of Si-based anodes. Electrochemical characterizations demonstrate that the method significantly enhances ICE, reaching from 66.7% to 115.4% after 10 min of prelithiation for SiO_x anodes and from 91.4% to 100.5% after just 90 s of prelithiation for Si anodes, while also stabilizing open-circuit voltage. Furthermore, microstructural analyses reveal the formation of a distinct solid electrolyte interphase layer after prelithiation. XPS depth profiling confirms the progressive lithiation of Si-based anodes, highlighting the formation of lithium oxide and lithium silicate compounds at varying depths with extended prelithiation times. These findings demonstrate the effectiveness of the proposed integrated prelithiation method in enhancing the electrochemical performance of Si-based anodes, paving the way for the development of high-energy-density LIBs.