Enhanced performance of fluorinated separator membranes for lithium ion batteries through surface micropatterning

Abstract

The increasing demand on electronic and portable devices requires battery system with improved energy storage capacity. Thus, studies in all battery components are being carried out to increase their performance. One of those battery components in the separator membrane. The present work reports on porous poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) separators with different patterned surfaces constituted by arrays of hexagons, lines, zig-zags and pillars microstructures and their influence on battery performance. Further, computer simulations allow to understand the influence of the patterned surface on battery response. It is observed that separator surface micropatterning increases battery performance. Thus, zig-zag surface micropatterning leads to a higher electrolyte current density (472.6 A.m(-2)), improved uptake value (262%), and larger ionic conductivity (3.00 mS cm(-1)) than the non-patterned separator. The increase of electrolyte/separator contact area (4.5 x 10(-7) m), leading to new pathways for lithium-ion diffusion, results in a discharge capacity efficiency similar to 804% (at 2C-rate) the one obtained for non-patterned separators. Thus, it is shown that micropatterning of separator membranes allow to significantly improve battery performance.