Facilitating Lithium-Ion Conduction in Gel Polymer Electrolyte by Metal-Organic Frameworks
Lü Xing, Haiping Wu, Dejia Kong, Xinru Li, Li Shen, Yunfeng Lu
Abstract
Gel polymer electrolytes (GPL) that comprise polymer, lithium salts, and organic plasticizers hold great promise for safer lithium-ion batteries, because of liquid-like ionic conductivity, as well as solid-like leakage-free property. However, only a small portion of ion conduction effectively carried by Li+ ions (or low Li+ transference number) gives rise to poor interfacial stability between GPL with electrodes and limited practicability. Here, metal-organic framework (MOF) containing open-metal sites (OMSs) are used as fillers that endow GPL simultaneously with high ionic conductivity (>1 mS cm–1) and a high Li+ transference number (up to 0.66), which results from immobilized anions and facilitated cation conduction by virtue of OMSs. Implementations of the GPL with OMSs-laden MOF in pseudo-solid-state batteries afford affinitive interfaces involving metallic Li and intercalation-type electrodes (LiFePO4, Li4Ti5O12), which contribute to significant improvements in battery durability and thereby could introduce a new type of MOF fillers for solid-state polymer electrolytes.