Anion conductive polymers: new development for energy devices

Research Project

Project/Area Number	22KF0156
Project/Area Number (Other)	22F22035 (2022)
Research Category	Grant-in-Aid for JSPS Fellows
Allocation Type	Multi-year Fund (2023) Single-year Grants (2022)
Section	外国
Review Section	Basic Section 26040:Structural materials and functional materials-related
Research Institution	University of Yamanashi
Principal Investigator	宮武健治山梨大学, 大学院総合研究部, 教授 (50277761)
Co-Investigator(Kenkyū-buntansha)	YADAV VIKRANT 山梨大学, 大学院総合研究部, 外国人特別研究員
Project Period (FY)	2023-03-08 – 2025-03-31
Project Status	Granted (Fiscal Year 2023)
Budget Amount *help	¥2,300,000 (Direct Cost: ¥2,300,000) Fiscal Year 2024: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 2023: ¥1,100,000 (Direct Cost: ¥1,100,000) Fiscal Year 2022: ¥700,000 (Direct Cost: ¥700,000)
Keywords	anion exchange membranes / fuel cells / water electrolyzers
Outline of Research at the Start	Designing and synthesis of alkali stable imidazolium salts, designing and synthesis of series-connected cycloaliphatic diamine-based tetra-cationic cross-linker, tethering of long alkyl chain on poly(p-phenylene) backbone, controlled cross-linking and quaternization on partially quaternized bromoalkylated poly(p-phenylene) will be carried out to develop robust AEM for anion exchange membrane fuel cell (AEMFC) applications. Other applications such as alkaline water electrolysis cells will also be investigated.
Outline of Annual Research Achievements	In this year,a series of 2,5-dichlorobenzene monomers differed in semi-fluoroalkyl pendant length were synthesized and copolymerized. The terpolymers provided bendable membranes by solution casting. The maximum ion conductivity of 112 mS/cm was achieved for the membrane formulated with C11 pendant. Cx-QPip-n membranes showed good alkaline stability, in particular, C11-QPip-1.86 retained 75% of the original conductivity after 1,056 h in harsh alkaline conditions (8 M KOH aqueous solution at 80 degrees C). C11-QPip-1.86 membrane was subjected to alkaline water electrolysis cell with Co-based platinum group metal-free anode catalyst which showed good performance. The cell was durable for 1000 h with minor voltage change at a constant current density operation.
Current Status of Research Progress	Current Status of Research Progress 2: Research has progressed on the whole more than it was originally planned. Reason According to the research plan, highly conductive and alkaline stable anion exchange membranes were developed and analyzed.
Strategy for Future Research Activity	The rational design and synthesis of AEM is planned by taking into consideration the loading of maximum number of quaternary ammonium groups on poly(p-phenylene) backbone so that resultant AEMs could avail desired properties. This will accomplish in two steps: i) Partial quaternization (60-80 mol% in relation to available bromine atoms) of bromoalkylated poly(p-phenylene) using imidazolium salt which showed long term alkaline stability using both techniques (NMR investigation and Density Functional Theory), and ii) controlled degree of cross-linking with simultaneous quaternization using series-connected tetra-cationic cross-linker which also showed long term alkaline stability. This approach mitigate trade-off between hydroxide ion conductivity and mechanical stability.