The lowest operational temperature of commercial graphite‖LiCoO₂ (LCO) batteries is limited to ∼−20 °C due to the high reaction energy barrier of Li⁺ in the interlayers of the graphite anode and the unstable solid electrolyte interphase (SEI) forming at low temperatures. Lithium (Li) metal with ideally host-less nature is expected to support the low-temperature operation of the LCO cathode, but low-temperature applications of Li‖LCO batteries are severely challenged with disastrous issues of conventional electrolytes including the high solvation structure of Li⁺, low desolvation energy, low Li⁺ saturation concentration, and LiF-barren SEI and cathode electrolyte interphase (CEI) (below 7%) with a small Li⁺ conductivity and diffusion coefficient. Here, using iso-butyl formate (IF) as an anti-freezing agent with an ultralow melting point of −132 °C and an ultralow viscosity of 0.30 Pa s, a fluorine–sulfur electrolyte is designed to achieve a low-coordination number (0.07), high desolvation energy (−27.97 eV) and high Li⁺ saturation concentration (1.40 × 10⁻¹⁰ mol s⁻¹) electrolyte, which enables efficient reversible transport of Li⁺ and formation of abundant F radicals to construct stable LiF-rich SEI (10.48%) and CEI (17.91%) layers with large Li⁺ conductivities (1.00 × 10⁻⁵ mS cm⁻¹ and 6.65 × 10⁻⁵ mS cm⁻¹) and large diffusion coefficients (1.10 × 10⁻²¹ m² s⁻¹ and 2.07 × 10⁻²⁰ m² s⁻¹). With the electrolyte, Li‖LCO batteries deliver unprecedented cyclic performances at −70 °C including a stable capacity of 110 mA h g⁻¹ over 170 cycles. The work provides an opportunity for developing ultralow-temperature LCO batteries.

中文翻译：

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通过超低温 LiCoO2 电池的抗冻电解质重建富含 LiF 的中间相

由于石墨负极层间_Li + 的高反应能垒^和在低温。具有理想无主体性质的锂 (Li) 金属有望支持 LCO 阴极的低温运行，但 Li‖LCO 电池的低温应用受到传统电解质灾难性问题的严峻挑战，包括高溶剂化结构Li ⁺，去溶剂化能低，Li ⁺饱和浓度低，LiF贫乏SEI和正极电解质界面（CEI）（低于7%）， Li ^+含量低电导率和扩散系数。在这里，使用甲酸异丁酯（IF）作为防冻剂，具有-132°C的超低熔点和0.30 Pa·s的超低粘度，氟硫电解质被设计为实现低配位数（ 0.07)、高去溶剂能(−27.97 eV)和高Li ⁺饱和浓度(1.40 × 10 ⁻¹⁰ mol s ^{−1 )电解质，可实现Li +}的高效可逆传输和大量F自由基的形成，从而构建稳定的富LiF SEI (10.48%) 和 CEI (17.91%) 层具有大的 Li ⁺电导率（1.00 × 10 ^-5 mS cm ^-1和 6.65 × 10 ^-5 mS cm ^-1) 和大扩散系数（1.10 × 10 ⁻²¹ m ² s ⁻¹和 2.07 × 10 ⁻²⁰ m ² s ⁻¹）。使用电解质，Li‖LCO 电池在 −70 °C 下提供前所未有的循环性能，包括在 170 次循环中稳定容量为 110 mA hg ^{−1 。}该工作为开发超低温LCO电池提供了机会。