LiFSI (lithium bis(fluorosulfonyl)imide) is a promising lithium salt for electrolytes in Li-ion batteries. However, the accumulation of harmful gases and heat during LiFSI hydrolysis could lead to serious safety accidents. Here we systematically investigate LiFSI hydrolysis processes under comprehensive conditions: higher temperature/acidity/basicity and lower water content can accelerate the hydrolysis, whereas the presence of DEC (diethyl carbonate) solvent, and other alkali metals (Na⁺, K⁺) can stabilize FSI⁻. Unexpectedly, under alkaline conditions, temperature/water content could not affect the hydrolysis greatly. By monitoring the hydrolysis intermediates and products using time-dependent ion chromatography, infrared spectra, and nuclear magnetic resonance, the hydrolysis routes are proposed and validated by accelerating rate calorimetry, differential scanning calorimetry measurements, and theoretical calculations. Under neutral/acidic conditions, electrophilic attack on the S–N bond generates FSO₂NH₂ and FSO₃⁻, while nucleophilic attack on the S–F bond produces FSO₂NSO₃²⁻ and SO₃NHSO₃²⁻ under alkaline conditions. As indicated by DFT calculation, the weaker S–N bond and larger S–N–S angle facilitate the electrophilic attack under acid conditions. Furthermore, very unstable intermediates (FSO₂NH₂ and CH₃CH₂OSO₃H) are determined for the first time. Based on these hydrolysis mechanisms, strategies for inhibiting LiFSI hydrolysis are provided, which is significant for the high-efficiency production and safe storage/transportation of LiFSI.

LiFSI（双（氟磺酰基）亚胺锂）是一种很有前途的锂离子电池电解质锂盐。然而，LiFSI水解过程中有害气体和热量的积累可能导致严重的安全事故。^{在这里，我们系统地研究了综合条件下的 LiFSI 水解过程：较高的温度/酸度/碱度和较低的水含量可以加速水解，而 DEC（碳酸二乙酯）溶剂和其他碱金属（Na +}，K ⁺）的存在可以稳定FSI ^-. 出乎意料的是，在碱性条件下，温度/含水量不会对水解产生很大影响。通过使用时间依赖性离子色谱、红外光谱和核磁共振监测水解中间体和产物，提出了水解路线并通过加速量热法、差示扫描量热法测量和理论计算进行了验证。在中性/酸性条件下，对 S–N 键的亲电攻击生成 FSO ₂ NH ₂和 FSO ₃ ⁻，而对 S–F 键的亲核攻击生成 FSO ₂ NSO ₃ ²⁻和 SO ₃ NHSO ₃ ²⁻在碱性条件下。如 DFT 计算所示，较弱的 S-N 键和较大的 S-N-S 角促进了酸性条件下的亲电攻击。此外，首次测定了非常不稳定的中间体（FSO ₂ NH ₂和 CH ₃ CH ₂ OSO _{3 H）。}基于这些水解机制，提供了抑制LiFSI水解的策略，这对于LiFSI的高效生产和安全储存/运输具有重要意义。