A gel polymer electrolyte based on PVDF-HFP modified double polymer matrices via ultraviolet polymerization for lithium-sulfur batteries

Abstract

Currently, as a new kind of separator, gel polymer electrolytes (GPEs) not only should play a role to separate cathode and anode, but also should have high ionic conductivity to guarantee the elevated electrochemical performances. As for quasi-solid-state lithium-sulfur batteries (LSBs), it is also very important to confine the shuttle effect and Li dendrite growth. Herein, we synthesize GPEs polymerized under ultraviolet, in which the poly(vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) is one of the polymer matrices to provide high ionic conductivity and toughness, pentaerythritol tetrakis-divinyl adipate (PETT-DA) is another polymer matrix to simultaneously suppress shuttle effect and lithium dendrite. More importantly, Li6.4La3Zr1.4Ta0.6O12 (LLZTO) provides the Li+ transport sites to facilitate the Li+ transport speed. Meanwhile, it can hinder the crystallization of polymers, reducing crystallinity of GPEs. Prominently, the designed GPEs with 10 wt% LLZTO have elevated ionic conductivity of 8.74 × 10−4 S cm−1 and Li+ transference number of 0.69, accompanied with superb capacity retention of 88.6% after 300 cycles at 1C. Importantly, the excellent mechanical properties and thermal stability give more potentials to the commercialization of LSBs.