Clay Nanosheets in Skeletons of Controlled Phase Inversion Separators for Thermally Stable Li‐Ion Batteries

Phase inversion is a powerful alternative process for preparing ultra‐thin separators for various secondary batteries. Unfortunately, separators prepared from phase inversion generally suffer from uneven pore size and pore size distribution, which frequently results in poor battery performance. Here, a straightforward route is demonstrated to solve the drawbacks of phase‐inversion‐based separators for Li‐ion batteries by means of directly incorporating 2D clay sheets in the skeleton of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) with multiscale pore generation from a simple one‐step solution coating method. Additionally generated pores by the inclusion of 2D nanosheets in PVdF‐HFP skeletons, combined with the multiscale pores (several micrometers + sub‐micrometers) originally generated by means of the controlled phase inversion, can generate additional ionic transport pathways, leading to Li‐ion battery performances better than those of commercialized polyethylene separators. Moreover, the addition of extremely low contents of 2D clay sheets in PVdF‐HFP separators allows thermally stable polymer separators to be realized.