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Compared with commercial polyolefin separators, the poor mechanical performance of electrospun polymeric membranes limits their usage as battery separators. Herein, poly(methyl methacrylate) (PMMA) and SiO2 nanoparticles were introduced into electrospun poly(vinylidene fluoride) (PVdF) membranes to form a PVdF/PMMA/SiO2 nonwoven membrane. A hot‐pressing method controlled the thickness of the electrospun membranes and improved their mechanical performance further. SEM tests show that PMMA partly melts in the composite membrane, which bonds neighboring electrospun fibers to reinforce the mechanical strength of the membrane. Uniformly distributed SiO2 nanoparticles on the electrospun fibers could supply higher resistance to mechanical impact. As a result, the composite membrane shows a high tensile strength (32.69 MPa) and high elongation at breakage (137.50 %). Differential scanning calorimetry and hot oven tests indicate that the composite membrane has excellent thermal stability. Furthermore, the addition of PMMA and SiO2 can decrease the crystallinity of PVdF and further improve the absorption of liquid electrolyte. According to the results of electrochemical tests, the composite membrane exhibits higher ionic conductivity (4.0×10−3 S cm−1) and lower interfacial resistance than those of the Celgard separator. The lithium‐ion cell assembled from the composite membrane exhibits more stable cycle performance, higher discharge capacity (158 mA h g−1), and excellent capacity retention.

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The problem of roadway support in swelling soft rock was one of the challenging problems during mining. For most geological conditions, combinations of two or more supporting approaches could meet the requirements of most roadways; however, in extremely swelling soft rock, combined approaches even could not control large deformations. The purpose of this work was to probe the roadway deformation mechanisms in extremely swelling soft rock. Based on the main return air-way in a coal mine, deformation monitoring and geomechanical analysis were conducted, as well as plastic zone mechanical model was analysed. Results indicated that this soft rock was potentially very swelling. When the ground stress acted alone, the support strength needed in situ was not too large and combined supporting approaches could meet this requirement; however, when this potential released, the roadway would undergo permanent deformation. When the loose zone reached 3 m within surrounding rock, remote stress p∞ and supporting stress P presented a linear relationship. Namely, the greater the swelling stress, the more difficult it would be in roadway supporting. So in this extremely swelling soft rock, a better way to control roadway deformation was to control the releasing of surrounding rock’s swelling potential.

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