A Skin‐Mimicked Polymer Gel Electrolyte for Stabilizing Lithium Metal Batteries

Animal skins usually display strong and tough mechanical properties even with a high loading of liquids inside. To address the trade-off between mechanical properties and ion-conductivity of gel polymer electrolytes with a high loading of liquid plasticizer, a skin-inspired nonflammable elastic gel polymer electrolyte (SINE-GPE) is successfully fabricated with both high gel-strength and ion-conductivity by anti-solvent induced self-assembly (ASISA) strategy.

Abstract

The electrolytes for advanced lithium-metal batteries need to simultaneously achieve high-performances in ion-conductivity, lithium-ion transference number, elasticity and mechanical strength, and safety etc. Gel polymer electrolytes (GPEs) are promising, however, conventional GPEs find it challenging to achieve all these performances, mainly due to a poor control of the liquid plasticizer inside. Here, inspired by the animal skins that can perfectly overcome the trade-off between the mechanics and complex biofunctions via water-encapsulation inside cellular network, it is attempted to design and fabricate a type of skin-inspired nonflammable elastic GPE (SINE-GPE) to address this challenge. To do that, an anti-solvent induced self-assembly (ASISA) strategy is proposed to fabricate a porous vesicular membrane based on a triblock thermoplastic polyurethane (i.e., the SINE-skeleton). Then, nonflammable liquid electrolyte is encapsuled inside the SINE-skeleton to prepare the SINE-GPE. The resultant SINE-GPE achieves not only a high gel-strength of 2.0 ± 0.1 MPa, a recoverable strain of 90% and a high ionic conductivity of 1.2 × 10⁻³ S cm⁻¹ at RT, but also selective lithium-ion transport (t_Li+ = 0.82). Consequently, this SINE-GPE can effectively stabilize lithium-metal anode with a smooth solid-electrolyte-interphase, which is explained by a self-massaging mechanism of the SINE-GPE during lithium stripping and deposition.