Ultra-long-life and ultrathin quasi-solid electrolytes fabricated by solvent-free technology for safe lithium metal batteries

The excessive consumption of organic solvent and enhancement of environmental protection protocols necessitate the exploitation of desirable approach to handle our solid-state electrolytes. Herein, we report an all solvent-free method for the preparation of low-cost, recyclability, flexible, ultrathin, and high ionic conductivity quasi-solid polymer electrolytes (QPE) membrane, which is an 5 μm-thick PE separators filled with polyether-block-polyamide (PEO-b-PA6)/LiTFSI/tetraethylene glycol dimethyl ether (TEGDME) (PPLT) that can be used as a safe lithium metal batteries. The self-fusion characteristics of the PEO-b-PA6 with supramolecular hydrogen bonds guarantees the intimate and perfect interfaces even during extreme deformations and crack of the solvent-free machining process. The ultrathin PE separators is mechanically strong, preventing batteries from short-circuiting even after more than 1200 h of cycling, and the ionic conductivity of PPLT reaches up to 1.02 × 10−4 S cm−1 at 30 ℃ by adding only 25 wt% of TEGDME as plasticizer. The LFP//Li cells using PPLT as electrolyte exhibits excellent reversible capacity of 116 mAh g−1 at 1 C after 700 cycles at 28 °C. In addition, the polymer soft-pack batteries using PPLT achieve highly reversible capacity of 124.9 mAh g−1 after 200 cycles at 0.2 C. It is noted that this solvent-free film-making process and outstanding electrochemical performance of this QPE could be further delivered to other room temperature rechargeable solid-state lithium metal batteries and enlighten safe, low-carbon green and high-energy solid-state batteries.