Electrolyte concentration is crucial for low-temperature aqueous batteries (LTABs) as it directly dictates electrolyte freezing point. However, the conventional approach for identifying suitable concentrations relies on determining freezing points of a large number of concentration combinations in the given H₂O–solute system, which is inefficient, particularly for multiple-solute systems. Here, we propose an approach to efficiently and rationally design anti-freezing electrolyte concentrations via the freeze concentration process. Freeze concentration is a process of concentrating dilute solution by precipitating ice or hydrates at target low temperatures (T_t). For single-solute systems, the frozen concentrated electrolyte (FCE) extracted from the liquid–ice mixture has, by nature, the lowest concentration (therefore the lowest cost) that remains unfrozen at T_t. For multiple-solute systems, instead of testing a large number of concentration combinations, the proposed approach can directly determine suitable concentrations via one freeze concentration experiment at T_t. As a demonstration, we successfully designed FCEs in H₂O–LiCl, H₂O–NaClO₄, and H₂O–NaClO₄–NaCF₃COO systems, and demonstrated superior performance in Li-based LiMn₂O₄//3,4,9,10-perylenetetracarboxylic diimide (PTCDI) and Na-based Na_1.4Co[Fe(CN)₆]_0.84·2.5H₂O//PTCDI full cells. This work provides a universal and efficient strategy to design electrolyte concentrations for LTABs.

中文翻译：

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冷冻浓缩工艺防冻电解液浓度的合理设计

电解质浓度对于低温水系电池 (LTAB) 至关重要，因为它直接决定电解质的凝固点。_{然而，确定合适浓度的传统方法依赖于确定给定H 2} O-溶质系统中大量浓度组合的冰点，这是低效的，特别是对于多溶质系统。在这里，我们提出了一种通过冷冻浓缩过程高效合理地设计防冻电解质浓度的方法。冷冻浓缩是通过在目标低温（ T _t ）下沉淀冰或水合物来浓缩稀溶液的过程。对于单溶质系统，从液冰混合物中提取的冷冻浓缩电解质（FCE）本质上具有在T _t时保持未冻结的最低浓度（因此成本最低） 。对于多溶质系统，所提出的方法可以通过T _t处的一次冷冻浓缩实验直接确定合适的浓度，而不是测试大量的浓度组合。作为示范，我们成功地设计了 H ₂ O–LiCl、H ₂ O–NaClO ₄和 H ₂ O–NaClO ₄ –NaCF ₃ COO 体系中的 FCE，并在锂基 LiMn ₂ O ₄ //3中展示了优异的性能,4,9,10-苝四甲酰二亚胺(PTCDI)和钠基Na _1.4 Co[Fe(CN) ₆ ] _0.84 ·2.5H ₂ O//PTCDI全电池。这项工作提供了一种通用且有效的策略来设计 LTAB 的电解质浓度。