A lithiated gel polymer electrolyte with superior interfacial performance for safe and long-life lithium metal battery

Rechargeable lithium metal batteries (LMBs) have gained much attention recently. However, the short lifespan and safety issues restrict their commercial applications. Here we report a novel gel polymer electrolyte (GPE) based on lithiated poly(vinyl chloride-r-acrylic acid) (PVCAALi) to realize dendrite-suppressing and long-term stable lithium metal cycling. PVC chains ensure the quick gelation process and high electrolyte uptake, and lithiated PAA segments enable the increase of mechanical strength, acceleration of lithium-ion transmission and improvement of interfacial compatibility. PVCAALi GPE showed much higher mechanical strength compared with other free-standing GPEs in previous works. It displays a superior ionic conductivity of 1.50 mS cm−1 and a high lithium-ion transference number of 0.59 at room temperature. Besides, the lithiated GPE exhibits excellent interfacial compatibility with lithium metal anodes. Lithium symmetrical cells with PVCAALi GPE yield low hysteresis of 50 mV over 1000 h at 1.0 mA cm−2. And the possible mechanism of the lithiated GPE with improved lithium-ion transfer and interfacial property was discussed. Accordingly, both the Li4Ti5O12/Li and lithium-sulfur (Li-S) cells assembled with PVCAALi GPE show outstanding electrochemical performance, retaining high discharge capacities of 133.8 mAh g−1 and 603.8 mAh g−1 over 200 cycles, respectively. This work proves excellent application potential of the highly effective and low-cost PVCAALi GPE in safe and long-life LMBs.