ZIF-8@MXene-reinforced flame-retardant and highly conductive polymer composite electrolyte for dendrite-free lithium metal batteries

A ZIF-8@MXene nanosheet reinforced polymer composite electrolyte was developed. In this electrolyte, abundant interactions and ion transport channels were generated by virtue of well-compatibility and plentiful functional groups and Lewis acid sites, enabling to high ionic conductivity and superior thermostability and flame retardance. This shows splendid potential for developing polymer electrolytes by cooperating two dimensional materials with MOFs. [Display omitted] •Developed Ti3C2-MXene nanosheets with horizontally extended ZIF-8 on the surface (ZIF-8@MXene) and a well compatible polymer composite electrolyte (PE- ZIF-8@MXene).•ZIF-8@MXene decreased the coupling of Li ion and polymer chain and provided ion transport channels to improve Li+ transportation.•Intrinsically stable ZIF-8@MXene enhanced the thermostability and flame resistance of electrolyte.•PE-ZIF-8@MXene presented a high ionic conductivity of 4.4 mS cm−1.•Assembled lithium batteries revealed a long cycling life up to 2000 h at 0.5 mA cm−2. Though polymer electrolytes have been regarded as promising separators for solid-state lithium metal batteries, their low ionic conductivity, poor thermostability and inflammability limit their practical applications. Herein, a polymer composite electrolyte consisting of metal–organic frameworks modified Ti3C2-MXene nanosheets (ZIF-8@MXene) and polymer mixture (PE-ZIF-8@MXene) was fabricated. The fabricated nonflammable ZIF-8@MXene nanosheets have abundant functional groups and Lewis acid sites as well as high specific surface area. In the composite electrolyte, ZIF-8@MXene nanosheets increased the dissociation of lithium salts and provided channels for transporting ions, accelerating the Li ion transportation. They also enhanced the tensile strength, thermostability and flame resistance of PE-ZIF-8@MXene. Consequently, the fabricated flame-retardant PE-ZIF-8@MXene presented high ionic conductivity (4.4 mS cm−1), impressive Li+ transference number (0.76) and enhanced tensile strength (3.77 MPa). In addition, the assembled Li|PE-ZIF-8@MXene|Li had a long cycle life of 2000 h, and Li|PE-ZIF-8@MXene|LiFePO4 batteries displayed a capacity retention of 89.6% after 500 cycles.