Bio-Inspired Polydopamine-Modified ZIF-90-Supported Gel Polymer Electrolyte for High-Safety Lithium Metal Batteries
Dongyun Wang, Biyu Jin, Xinyu Yao, Jiao Huang, Yongyuan Ren, Xiao Xu, Xiao Han, Fanqun Li, Feng Gao, Xiaoli Zhan, Qinghua Zhang
Abstract
Gel polymer electrolytes (GPEs) with high ionic conductivity and good flexibility have emerged as promising alternatives to traditional liquid electrolytes. Metal–organic frameworks (MOFs), with a hierarchical pore structure and high porosity, have attracted widespread attention as high-performance solid electrolytes. However, severe agglomeration of MOF particles hampers Li + transport, and the flammability of organic liquid electrolytes in GPEs poses safety risks. Herein, inspired by the bioadhesive properties of marine mussels, we developed novel polydopamine (PDA)-modified zeolitic imidazole framework-90 (ZIF-90) nanoparticles to act as a robust support layer. Based on the nonflammability and environmental friendliness of ionic liquids (ILs), through thiol–ene click chemistry, an IL-based gel is fabricated. PDA exhibits exceptional interfacial bonding between organic and inorganic components, thereby facilitating efficient Li + transfer. The stable three-dimensional open framework of ZIF-90 anchors bulky ions of IL and lithium salt while allowing unrestricted movement of small Li + . The nanowetting interface formed by ZIF-90 and IL, along with the polyether segments on the gel backbone, further facilitates Li + migration. The resulting ZIF-90@PDA GPE exhibits a high ionic conductivity of 2.98 × 10 –4 S cm –1 at 30 °C and a lithium-ion transference number of 0.43. Moreover, enhanced suppression of lithium dendrite growth, along with notable thermal stability and flame retardancy is achieved. The assembled LiFePO 4 /Li cell demonstrates remarkable cycling performance, exhibiting an initial discharge capacity of 140 mAh g –1 at 30 °C and 0.5 C, with a capacity retention of 90% after 300 cycles.