Zheng Jing, Chen Ran, Nie Luanjie, Chu Xiaokang, Wang Hao, Xia Haobo, Lin Yuxiao, Li Yunsong, Lin Zixia, Xue Fei, Ma Mengtao, Lai Qingxue
Department of Chemistry and Materials Science, College of Science, Nanjing Forestry University, Nanjing 210037, PR China.
Department of Chemistry and Materials Science, College of Science, Nanjing Forestry University, Nanjing 210037, PR China.
J Colloid Interface Sci. 2025 Dec;699(Pt 1):138164. doi: 10.1016/j.jcis.2025.138164. Epub 2025 Jun 10.
Weakly solvated electrolytes (WSE) have been proposed for potassium-ion batteries (PIBs) to address the interfacial stability issue of K-storage via weakening the cation-solvent interaction to achieve anion-rich solvation sheath for constructing anion-derived stable solid electrolyte interface (SEI) film. However, the insufficient salt dissociation capacity of the employed solvents with low solvation ability significantly limited the wide manipulation of solvation structures for realizing satisfactory K-storage performance. Herein, a dual weakly solvated electrolytes (DWSE) was developed for alloy-type Bi-based K-storage anode. The dual weakly solvated structures with abundant contact ion pair (CIP) and aggregate (AGG) were manipulated via employing a cyclic ether of tetrahydrofuran (THF) with monovalent coordination with K as the bulk solvent, and increased salt concentrations simultaneously. The prepared carbon confined Bi anode (Bi@C) in the optimized DWSE delivered a distinct three-step alloying mechanism with high reversible capacity (468 mAh/g at 50 mA/g), cycling stability (381 mAh/g after 100 cycles at 50 mA/g) and rate properties (336 mAh/g even at 400 mA/g). The fast ion transfer kinetics and anion-derived KF-rich SEI were revealed to be responsible for the excellent K-storage performance of Bi@C anode. These results provide a new thought for the electrolyte development of advanced energy storage devices.
弱溶剂化电解质（WSE）已被提出用于钾离子电池（PIB），旨在通过削弱阳离子与溶剂的相互作用来解决钾存储的界面稳定性问题，从而实现富含阴离子的溶剂化鞘层，以构建阴离子衍生的稳定固体电解质界面（SEI）膜。然而，所采用的具有低溶剂化能力的溶剂的盐解离能力不足，显著限制了溶剂化结构的广泛调控，难以实现令人满意的钾存储性能。在此，我们开发了一种用于合金型铋基钾存储阳极的双弱溶剂化电解质（DWSE）。通过使用与钾具有单价配位的四氢呋喃（THF）环状醚作为主体溶剂，并同时提高盐浓度，调控了具有丰富接触离子对（CIP）和聚集体（AGG）的双弱溶剂化结构。在优化的DWSE中制备的碳限制铋阳极（Bi@C）呈现出独特的三步合金化机制，具有高可逆容量（50 mA/g时为468 mAh/g）、循环稳定性（50 mA/g下100次循环后为381 mAh/g）和倍率性能（即使在400 mA/g时也为336 mAh/g）。快速的离子传输动力学和富含阴离子的KF衍生SEI被证明是Bi@C阳极优异钾存储性能的原因。这些结果为先进储能器件的电解质开发提供了新的思路。
