Quasi-solid polymer electrolytes with fast interfacial transport for lithium metal batteries

The quasi-solid electrolyte based on Poly(vinylidene fluoride-co-hexafluoropropylene) has drawn great interest owing to good wettability and compatibility with lithium metal anode. However, the low ionic conductivity and lithium-ion transfer number limit the practical application of Poly(vinylidene fluoride-co-hexafluoropropylene). Herein, quasi-solid electrolyte is prepared by adding NASICON-type lithium-ion conductor Li1.3Al0.3Ti1.7(PO4)(3) to Poly(vinylidene fluoride-co-hexafluoropropylene). The Li1.3Al0.3Ti1.7(PO4)(3) not only reduces the crystallinity of the polymer, but also participates in the conduction process of Li+. Through the synergistic effect of Li1.3Al0.3Ti1.7(PO4)(3) and Poly(vinylidene fluoride-co-hexafluoropropylene), the quasi-solid polymer electrolyte has a high ionic conductivity (3.64 x 10(-3 )S cm(-1)) at room temperature and large lithium-ion transfer number (0.64). The symmetric cell exhibits a small overpotential (18 mV) as well as a stable cycle (3000 h) at 0.2 mA cm(-2 )with areal capacity of 0.2 mAh cm(-2 ). The full cell with LiFePO4 cathode keeps a discharge capacity of 143.4 mAh g(-1) after 600 cycles with capacity retention of 94.7%, and also performs good electrochemical performance with high voltage cathode (LiNi0.85Mn0.1Co0.05O2). Furthermore, the pouch cell assembled by quasi -solid polymer electrolyte have good flexibility, which can be used normally after folding and shearing. Our work supplies a feasible solution for the design of quasi-solid lithium metal batteries.