Rational Integration of Multiple Additives for High-Temperature Lithium-Ion Batteries

The rational combination of multiple electrolyte additives is a promising strategy for constructing stable interphases in lithium-ion batteries. However, unintended additive interactions can alter the preferential reduction/oxidation pathways at electrode surfaces, compromising cell performance. In this study, we identify a detrimental interaction between succinonitrile (SN) and lithium bis(oxalato)borate (LiBOB) on a graphite-silicon (Gr-Si) anode. Specifically, an electron-deficient boron-embedded solid electrolyte interphase (SEI) derived from LiBOB promotes the reduction of the electron-rich nitrile moieties of SN, disrupting fluoroethylene carbonate (FEC)-driven SEI construction. Based on this mechanism, SN was replaced with triisopropanolamine borate (TPAB), which mitigates transition metal dissolution through its amine moiety while forming a robust borate-based cathode electrolyte interphase. Moreover, TPAB combined with LiBOB avoided detrimental side reductions at the anode–electrolyte interface. The FEC-LiBOB-TPAB combination creates thermally stable interphases on the Gr-Si anode and LiNi0.91Co0.08Al0.01O2 cathode (4.8 mAh cm–2), enabling 68.7% capacity retention after 300 cycles at 45 °C and 1C.