Balancing Ionic and Electronic Conduction at the LiFePO4 Cathode-Electrolyte Interface and Regulating Solid Electrolyte Interphase in Lithium-Ion Batteries

Recently, in electric mobilities and stationary energy storage device applications, the development of long-lasting, low-cost, and high-safety lithium-ion batteries (LIBs) is widely studied. LiFePO4 (LFP) is a core cathode material for LIBs owing to its cost-effectiveness and high safety. However, it exhibits low electronic conductivity and sluggish Li+ diffusion, hindering the application of LFP cathodes in high-power battery industries. Herein, a triazole-motivated electrolyte additive, 1-(trimethylsilyl)-1H-benzotriazole (TMSBTA) is presented, for mitigating iron dissolution via HF scavenging, reinforcing the robustness of the solid electrolyte interphase and constructing a cathode-electrolyte interface (CEI) to balance the ion and electron conduction of the CEI on the LFP cathode. Scanning probe microscopy performed in the conductive atomic force microscopy mode indicates that the electronically conductive CEI created by the oxidative decomposition of TMSBTA enables rapid and homogeneous lithiation and delithiation during cycling without morphological changes in the LFP particles. This study elucidates the design principles of the CEI on the LFP cathode and is expected to guide integrated electrolyte additive engineering for LFP-containing LIBs.