Guo Xiaoyu, Xu Shengtao, Gu Rong, Zhang Da, Gong Shuaiqi, Xu Jinting, Gao Qingwei, Xu Qunjie, Min Yulin
Shanghai Key Laboratory of Materials Protection and Advanced Materials Electric Power, Shanghai University of Electric Power, Shanghai, 200090, P. R. China.
Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, P. R. China.
Angew Chem Int Ed Engl. 2025 Jan 30:e202414613. doi: 10.1002/anie.202414613.
Insufficient ionic conductivity and elevated desolvation energy barrier of electrolytes limit the low-temperature applications of lithium metal batteries (LMBs). Weakly solvating electrolytes (WSEs), with limited lithium salt dissociation capability, are prone to desolvate and drive anion-rich aggregates (AGGs). However, significant AGGs result in increased viscosity and low ionic mobility, contributing to battery failure at low temperatures (≤-20 °C). Here, we propose and achieve a transformation of WSEs' solvation structures from AGGs to contact ion pairs (CIPs) through modulating the overall solvation capability, thereby achieving the balance between weak Li- solvent interactions and desired ion migration kinetics. Remarkably, CIPs-dominated electrolyte shows a ten-fold increase in ionic conductivity compared to conventional WSEs. The Li||LiFePO (LFP) battery achieves more than 1400 cycles with 86.9 % capacity retention at 5 C. The practical 1.2 Ah LFP pouch cell delivered 69 % of the capacity at 25 °C when cycled at -40 °C. This strategy for solvation structure transformation in WSEs provides a novel approach for the development of electrolytes for low-temperature batteries.
电解质的离子电导率不足和去溶剂化能垒升高限制了锂金属电池（LMBs）在低温下的应用。弱溶剂化电解质（WSEs）的锂盐离解能力有限，容易发生去溶剂化并驱动富阴离子聚集体（AGGs）。然而，大量的AGGs会导致粘度增加和离子迁移率降低，从而导致电池在低温（≤-20°C）下失效。在此，我们提出并通过调节整体溶剂化能力实现了WSEs溶剂化结构从AGGs到接触离子对（CIPs）的转变，从而在弱锂-溶剂相互作用和所需的离子迁移动力学之间实现了平衡。值得注意的是，以CIPs为主的电解质的离子电导率比传统WSEs提高了十倍。Li||LiFePO（LFP）电池在5C下实现了超过1400次循环，容量保持率为86.9%。实际的1.2Ah LFP软包电池在-40°C循环时，在25°C下的容量为69%。这种WSEs溶剂化结构转变策略为低温电池电解质的开发提供了一种新方法。
