Comparing measurement of limiting current in block copolymer electrolytes as a function of salt concentration with theoretical predictions

•Optimizing electrolyte performance.•Limiting current provides a robust criterion for determining the optimum electrolyte.•Experiments were conducted on rigid block-copolymer electrolytes mixed with LiTFSI.•The dependence of limiting current on salt concentration is in good agreement with predictions from concentrated solution theory. Optimizing electrolyte performance is crucial for the widespread adoption of electrochemical energy storage. We demonstrate that limiting current provides a robust criterion for determining the optimum electrolyte. Experiments were conducted on rigid block copolymer electrolytes comprising mixtures of polystyrene-block-poly(ethylene oxide) copolymer (SEO) and lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI) over a salt concentration range from rav = 0.04 to rav = 0.20 (rav is the molar ratio of lithium ions to ethylene oxide). We show that the maximum limiting current density is 4.3 mA cm−2 at rav = 0.12. The dependence of limiting current on salt concentration is in good agreement with predictions from Newman's concentrated solution theory with no adjustable parameters. [Display omitted]