Deciphering the Purification Additive Chemistries for Ultra‐Stable High‐Voltage Lithium‐Ion Batteries

Abstract Hydrogen fluoride (HF)‐induced degradation of electrode materials and interphases presents a significant challenge for high‐voltage Li‐ion batteries. However, progress in developing advanced HF‐scavenging additives is hindered by a limited understanding of HF‐elimination reactions and the absence of a robust design principle. Herein, it is proposed to analyze the energy decomposition analysis of 24 additives to elucidate the underlying HF‐scavenging mechanism and identify key factors influencing HF‐additives reactions. The findings reveal that orbital contribution ratio (OCR) is a critical determinant of chemical bonding in HF‐additive reactions. Specifically, an 80% OCR for H ⁺ and a 53% OCR for F ⁻ are essential for completing HF elimination. Based on these insights, a general principle for designing effective HF‐elimination additives is proposed and heptamethyldisilazane as a particularly well‐suited candidate, exhibiting optimal OCR for both H ⁺ and F ⁻ ions is identified. Remarkably, the addition of just 1 wt.% HMDS significantly eliminats HF, inhibiting cathode‐to‐anode crosstalk behaviors and limiting electrode and interphase degradation. This guardian endows graphite/LiNi _0.8 Co _0.1 Mn _0.1 O ₂ pouch cells with a significant performance improvement, achieving 80% capacity retention over 2528 cycles, a substantial improvement compared to the 1139 cycles observed without HF‐elimination additive. The study provides valuable insights for the design of advanced electrolyte additives for high‐performance Li‐ion batteries.