Nano-porous bnnt composite with thermal switching for advanced batteries

Abstract

Thermoresponsive composite switch (TRCS) membranes for ion batteries include a porous scaffolding providing ion channels and a thermoresponsive polymer coating. Boron nitride nanotube (BNNT)/polymer composite TRCS membrane embodiments are preferable due to unique BNNT properties. A BNNT scaffold coated with one or more polymers may form a composite separator with tunable porosity (porosity level and pore size distribution), composition, wettability, and superior electronic isolation, oxidative/reduction resistance, and mechanical strength. The BNNT/polymer composite TRCS membrane optimizes the performance of ion batteries with tunable separator thicknesses that may be under 5 μιη. Nano-scale porosity with thin separator thicknesses improves the charge density of the battery. Nano-scale architecture allows for reversible localized switching on the nano scale, in proximity to thermally stressed ion substrates. Polymer thermal expansion will decrease porosity at temperatures approaching the thermal runaway point. The BNNT polymers composite therefore functions as a TRCS.