钾离子电池低温电解质的研究进展

Advances in low-temperature electrolytes for potassium-ion batteries

钾离子电池因其能量密度高、廉价易得等特点,已成为有潜力的储能设备,尤其钾离子更小的斯托克斯半径,使超低温钾离子电池成为可能。然而,传统电解质会使钾离子电池在低温下生长枝晶,导致电池失效并造成安全隐患。因此,改善电解质的低温特性对提高钾离子电池低温性能至关重要。本文综述了近些年钾离子电池低温电解质的研究进展,其大致可分为三类,即非水系电解液、水系电解液和固态电解质。其中,非水系电解液大多含弱溶剂化醚类溶剂和添加剂,提高界面去溶剂化过程的同时使电极表面形成良好的界面膜,以提高电池的低温性能;水系电解液通过引入特定的添加剂分子降低电解液凝固点的同时破坏H2O分子间氢键网络,实现电池低温性能;固态电解质以准固态电解质为主,使聚合物骨架孔道中保留少量液态电解液以提高电解质体相离子传输,并降低电解质与电极界面接触阻抗,最终提高电池的低温性能。

Potassium-ion batteries(PIBs)have emerged as a potential energy storage device due to their high energy density and low cost.In particular,the smaller Stokes radius of K+enables ultra-low temperature potassium-ion batteries.However,conventional electrolytes can cause PIBs to grow dendrites at low temperatures,leading to battery failure and safety hazards.Therefore,improving the low-temperature properties of the electrolyte is crucial to improving the low-temperature performance of PIBs.This study reviews the progress made in recent years related to low-temperature electrolytes for PIBs,which can be roughly divided into three categories,namely non-aqueous electrolytes,aqueous electrolytes,and solid electrolytes.Non-aqueous electrolytes mostly contain weakly solvating ether solvents and additives,which enhance the interfacial desolvation process and form a good solid electrolyte interface film on the electrode surface to improve the low-temperature performance of PIBs.The aqueous electrolyte helps PIBs to achieve good low-temperature performance by introducing specific additive molecules to lower the electrolyte freezing point and destroy the network of hydrogen bonds between the H2O molecules.The quasi-solid-state electrolyte,which retains a small amount of liquid electrolyte in the channels of the polymer skeleton,improves the electrolyte bulk ion transport and reduces the contact resistance between the electrolyte and the electrode interface,which ultimately improves the low-temperature performance of PIBs.