Preparation of PVDF/KH570-SiO2/UHMWPE Li-Ion Battery Composite Separator via Coaxial Electrospraying/Electrospinning Method

Separators are considered a key component in lithium-ion batteries (LIBs); however, currently commercial polyolefin separators fall short in meeting the demands of high-performance LIBs due to their low porosity and other issues. In this paper, a novel coaxial electrospray/electrospinning device consisting of an outer nozzle and an inner nozzle is presented, which can simultaneously prepare composites containing nanofibers and nanoparticles. With this device, a new type of LIB separator was successfully fabricated by simultaneously spinning fibers of PVDF and spraying particles of KH570/SiO2 in situ onto an ultra-high molecular weight polyethylene (UHMWPE) separator. The average diameter of the fibers prepared from the inner nozzle is 0.46 μm, and the average diameter of the particles prepared from the outer nozzle is 70.81 nm. According to the analytical results, the porosity of the separator increases from 37.85% to 81.33%, and the longitudinal shrinkage decreases from 7.28% to 2.63% compared to the unmodified separator. Additionally, the initial charge/discharge specific capacity of the experimental separator increases from 107.8 to 152.0 mAh·g−1. Excellent cycling stability of the separators is also exhibited after 50 charging and discharging cycles.