Konovalova, Anastasiia Stock, Daniel Schroeder, Steffen Park, Hyun S. Jang, Jong Hyun Kim, Hyoung-Juhn Han, Jonghee Schroeder, Daniel Henkensmeier, Dirk 2024-01-19T17:00:37Z 2024-01-19T17:00:37Z 2021-09-02 2020-09 0376-7388 https://pubs.kist.re.kr/handle/201004/118233 Hydroxide ion conductive polymer coatings with a low permeability for zinc species reduce shape change and dendrite formation of zinc anodes, and reduce the capacity fade over charge/discharge cycles. Herein we focus on the material properties and aim to minimize the permeability of polybenzimidazole (PBI) for zincate ions by methylating its imidazole NH groups. This reduces the volume swelling in 4 M KOH solution from 104% for PBI to 20% for a PBI with 1.3 methyl groups per repeat unit. Similarly, materials with a degree of methylation (DOM) between 0.96 and 1.2 show very low uptake of KOH. Above a DOM of 1.7 decreasing alkaline stability is observed, presumably because a fraction of the imidazole groups is permethylated to benzmidazolium ions. Most importantly, membranes with a DOM around 1-1.2 revealed the lowest permeation for zincate ions, with permeability coefficients P of 0.9-1.5 10(-9) cm(2) s(-1), 3000 times lower than for PBI. At higher DOM slightly higher P values were observed. In a Zn/NiOOH cell an optimized anode coating with 0.96MePBI led to better cycling stability than with PBI, and an initial capacity of 265 mAh (g anode)(-1). English ELSEVIER Partially methylated polybenzimidazoles as coating for alkaline zinc anodes Article 10.1016/j.memsci.2020.118254 1 JOURNAL OF MEMBRANE SCIENCE, v.610 JOURNAL OF MEMBRANE SCIENCE 610 N scie scopus 000555548800008 2-s2.0-85084844062 Engineering, Chemical Polymer Science Engineering Polymer Science Article AIR BATTERIES MEMBRANES TEMPERATURE STABILITY ACID SEPARATOR FRAMEWORK POLYMERS IONOMER Alkylated polybenzimidazole Hydroxide ion conductivity Zincate ion permeability Zinc oxygen battery Anode coating