Nylon binder enables high-performance flexible ultra-thick electrode preparation in a water-based environment

Abstract

The demand for high-energy-density lithium-ion batteries has spurred the development of advanced thick electrodes. However, conventional polyvinylidene fluoride (PVDF) binders face challenges like weak adhesion and the use of environmentally unfriendly N-methylpyrrolidone (NMP) solvent, hindering the industrial processing of high-loading electrodes. In this study, a fully recyclable lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) aqueous solution is employed to dissolve nylon (PA, including polylaurylamide, PA12, and nylon elastomer, TPAE) as an aqueous binder, allowing the preparation of LFP/CNT/PA thick electrodes through a water-based phase conversion method. The strong adhesion and flexible chains of nylon lead to an integral conductive porous network structure in the flexible electrode film, with a controllable thickness ranging from 20 to 3000 μm. Moreover, the polar groups in TPAE can enhance lithium ion diffusion, leading to excellent rate performance and an areal capacity of 36.2 mA h cm⁻². Additionally, this PA-based aqueous binder is also suitable for anode preparation, enabling the fabrication of a flexible LFP//Gr battery with stable voltage output under various bending states. This study not only introduces a new aqueous binder but also showcases a method for producing flexible thick electrodes.