Poly(vinylidene fluoride)-based composite membranes with continuous metal–organic framework layer for high-performance separators of lithium-ion batteries

Lithium-ion batteries (LIBs) play a critical role in modern portable electronic devices, electric vehicles, and wearable electronics. However, the formation of lithium dendrites during cycling results in serious capacity loss and safety risks owing to the heterogeneous transport and deposition of Li+. In this work, we present a poly(vinylidene fluoride) (PVDF)-based composite membrane with a continuous metal–organic framework (MOF) layer as high-performance separators in LIBs. The PVDF membranes with uniform pore structures are prepared by using superspreading strategy, facilitating the growth of continuous and controllable MOF layer inside the membranes via a simple interfacial synthesis. The as prepared PVDF-MOF composite membranes display uniform and continuous subnanochannels with connected opened metal sites (OMS), which can generate a homogeneous transport of Li+. Taking advantages of the low impedance (∼2 Ω), high ionic conductivity (0.61 mS cm−1), and high stripping peak current (0.89 mA cm−2), the PVDF-MOF composite separators efficiently prevent the uneven deposition and the generation of lithium dendrites. Moreover, the PVDF-MOF-based LIBs showed a high capacity retention rate of 81.0 % after 250 cycles. This strategy paves a new avenue for MOF-based composite separator in LIBs.