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Ceramic‐coating separator produced by aqueous slurry has drawn considerable attention because of its environmental friendliness in the development of high‐power lithium ion battery (LIB). However, there are some drawbacks existed including the formation of compact coating layer and uneven distribution of slurry. In this study, porous sodium alginate/boehmite coating layer was designed to cover on low‐cost PP nonwoven to give a battery separator (abbreviated as PCS) through polydopamine‐ induced water‐based coating method, in which nonsolvent N‐methyl pyrrolidone (NMP) was added to render porous structures through its final evaporation and the pretreatment of polydopamine on substrate could help slurry dispersed uniformly. Thoroughly investigations demonstrate this designed separator can not only endow battery with superior cell performance but also display good thermal dimensional stability and self‐extinguishing behavior. Therefore, PCS composite separator is low‐cost, environmentally friendly and feasible to meet performance requirements of high‐power LIB.

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Non-woven based battery separators have been developed rapidly in recent years due to their unique advantages in process, cost and performance. In this study, a novel double-crosslinked three-dimensional network coating was constructed by hyperbranched polyethyleneimine (PEI), Polydimethylsiloxane diglycidyl ether (PDMSDGE) and poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP. Then the caoting used to modify tissue paper, which composed of packed cellulose fibers is typical nonwoven with excellent hydrophilic properties required for lithium separators. As we expected, the composite separator shows unique advantages in terms of porosity, electrolyte absorption, mechanical properties and thermal stability. At the same time, the nucleophilic hyperbranched PEI in the coating makes the composite separator in a lithium-rich state in lithium ion battery, so the separator has a certain electric pumping capacity by electrokinetic surface conduction and electroosmosis. As a result, the electrochemical performance and battery performance are excellent too. In addition, we compared the performance of the double-crosslinked coating with two systems of single-crosslinked coating, PEI/PDMSDGE and PEI/PVDF-HFP. The results showed the excellent performance of the composite separator with double-crosslinked coating in terms of mechanical properties retention (95.05%) after electrolyte infiltration and discharge capacity retention (86.89%) after 200 cycles, which given by the stable molecular structure of the three-dimensional double-crosslinked network.