In situ formed self-healable quasi-solid hybrid electrolyte network coupled with eutectic mixture towards ultra-long cycle life lithium metal batteries

Abstract

The exploration of high-performance polymer-based electrolyte have great promise for the development of next-generation lithium metal batteries. In this study, a self-healable quasi-solid hybrid electrolyte network coupled with deep eutectic solvent (X-PPS-D4) was prepared by polyaddition reaction, photo-initiated free-radical crosslinking, and physical blending. X-PPS-D4 not only possessed high ionic conductivity (σ) of 2.03✗10−4 S cm−1 at 30 ℃ but also wide electrochemical stability window (0∼5.0 V vs. Li+|Li). The enhanced lithium ion transference number (tLi+= 0.44) for X-PPS-D4 resulted from reduction of anion mobility that was proved by spectral analysis together with nuclear magnetic resonance study and theoretical calculation. Under testing temperature of 30 ℃, X-PPS-D4 could support stable long-term (>1300 h) plating/stripping tests of lithium symmetrical cell at current density of 0.1 mA cm−2. More importantly, the in situ formed X-PPS-D4 on LiFePO4 cathode within the coin cell facilitated excellent cell performance with specific capacity over 100 mA h g−1 at 5 C and ultra-long cycle life (>1000 cycles) with high delivered specific capacity at 1 C (>116.1 mA h g−1 after 1000 cycle). X-PPS-D4 also supported coin cells with high voltage cathode to perform decently. This research provides new insights into structure-property relationship of quasi-solid hybrid electrolyte with eutectic mixture and offered an effective way to develop high-performance polymer-based electrolytes for LMBs.