A Novel Na-β″-Al<sub>2</sub>O<sub>3</sub> Nanosheet Enhanced Environmentally Friendly Solid Electrolyte for a Highly Stable Na–Metal Battery
Jing-xuan Li, Liang Zhong, Heng-fei Wu, Liping Zhou, Ying Liu, Zhou Wang, Gang Zhang, Lianli Zou, Mao‐xiang Jing
Abstract
The use of low-cost and easy-to-prepare solid electrolytes is expected to yield sodium-ion batteries with good chemical and thermal stability. However, the current solid electrolytes generally suffer from the defects of poor electrochemical performances, high fabrication cost, demanding fabrication environment, and serious pollution caused by the release of a large amount of organic solvents during the preparation process. Herein, an environmentally friendly polymer-based solid electrolyte was prepared by using a water-soluble triblock copolymer (Pluronic F127), sodium perchlorate as sodium salt, and water as solvent. The whole preparation process contains no organic pollutants and is accomplished under an air atmosphere. In addition, the introduction of Na-β″-Al 2 O 3 nanosheet-like fillers not only improves the ionic conductivity of the solid electrolyte by lowering the glass transition temperature ( T g ) and releasing more free sodium ions, but also improves the stability of the electrolyte/sodium anode interface through the reaction of Na-β″-Al 2 O 3 with the sodium anode to form a stable solid electrolyte interphase (SEI). The ionic conductivity and electrochemical window of the electrolyte were as high as 5.33 × 10 –4 S cm –1 and 4.8 V, respectively. The assembled Na 3 V 2 (PO 4 ) 3 /Na battery also exhibited good rate and cycling performance, which could be charged and discharged at 1 C and stably cycled more than 500 times at 0.3 C with a capacity retention rate of 95%. This low-cost environmentally friendly and easy-to-manufacture sodium-ion solid electrolyte provides a new idea and technology for the practical application of highly stable sodium-ion batteries.