Designing of multilevel-nanofibers-based organic-inorganic hybrid gel electrolyte enabling an innovative lithium-ion battery with superior ionic transport capability and advanced security

摘要

Separator plays a key background role in maintaining excellent ionic flux and avoiding the subject of internal short-circuit faults, which is thought as the key-part of lithium-ion battery. Hence, the characteristics of prominent thermal stability, eminent electrolyte affinity and laudable mechanical strength are of vital importance to guarantee energy density and security for lithium-ion cells. In this study, a natty poly(vinylidene fluoridehexafluoropropylene) (PVDF-HFP)-based gel membrane with multi-level nanofibers was resoundingly prepared for the first time through blend electrospinning of manganese dioxide (MnO2) particles and poly-m-phenyleneisophthalamide (PMIA) solution. The organic-inorganic hybrid multi-level gel electrolyte presented relatively high porosity, small aperture, superior electrolyte uptake and outstanding heat-resistance. Moreover, the mutual overlaps between the coarse fibers and the fine fibers within the multi-level nanofiber membrane provided a strong skeleton support to suppress the lithium-dendrites growth, resulting in an appealing safety for the resulting batteries. And the existence of the multi-level nanofibers can significantly accommodate more sufficient active sites and shorter diffusion channels to accelerate lithium ions migration. Depend on these benefits, the asassembled cells using the hybrid PMIA separator delivered superior ionic conductivity (2.27 x 10(-3) S cm(-1)) and steady anodic stability window (similar to 5.01 V). The most extraordinary was that the capacity retention of the resulting lithium-ion cell reached up to 90.5% after 200 cycles at 0.5 C, while the Celgard PP separator merely achieved to 70.2%. This work proved that the addition of functional inorganic particles similar with MnO2 in gel PVDF-HFP-doped PMIA membrane with multi-level structure could enhance the lithium ions transport capability and resist the growth of lithium dendrites, which would prompt a great development of lithium-ion cells with reassuring safety and high energy.