Reactive Aramid Nanofiber-Reinforced Polyvinyl-Alcohol-Based Solid Polymer Electrolyte for High-Performance Li Metal Batteries
Yujun Zheng, Yinghao Tao, Wenyao Guo, Sheng Zhu, Jinchen Fan, Yulin Min
Abstract
Solid polymer electrolytes (SPEs) with high ionic conductivity and strong mechanical properties are preconditions for the stable cycling of high-performance Li metal batteries. However, single-polymer SPEs often have low ionic conductivity, which greatly limits their further application. Herein, a SPE composed of polyvinyl alcohol (PVA), reactive aramid nanofibers (RANFs), and lithium bistrifluoromethanesulfonimide (LiTFSI) is prepared using a simple solution-casting method. After introducing the RANFs, the SPE of RANFs/PVA-containing LiTFSI not only exhibits high mechanical properties but also has good thermal stability. The RANFs/PVA SPE constructed from the strong hydrogen bond interaction between rigid RANFs and flexible PVA shows high migration efficiency of lithium ions. When the loading amount of RANFs is 2 wt %, the ionic conductivity of RANFs/PVA reaches ∼7.7 × 10 –4 S·cm –1, and the lithium-ion migration number is ∼0.54 at 60 °C. Toward the Li|RANFs/PVA-2 wt %|LiFePO 4 full cell, the discharge specific capacity could reach 162.5 mA h·g –1 at 60 °C and 0.1 C. Meanwhile, the Li|RANFs/PVA-2 wt %|LiFePO 4 battery also shows outstanding long-term cycling performance and could maintain 81% of the initial capacity after 1200 cycles at 1 C. The solid-state Li|RANFs/PVA|LiFePO 4 cell also exhibits excellent resilience in destructive tests such as cell bending, piercing, and cutting.