Effect of Porous Transport Layer on Zero-Gap Alkaline Water Electrolysis

Abstract

Green hydrogen refers to hydrogen produced without emitting greenhouse gases into the atmosphere and is eco-friendly because it extracts hydrogen from carbon-neutral fuels such as water or ammonia. Water electrolysis, a method of producing hydrogen from water, is a next-generation hydrogen production technology that can achieve carbon neutrality in the entire process of hydrogen production by utilizing renewable energy generated from solar or wind power, not electricity generated from thermal power generation. Among them, alkaline water electrolysis is widely used due to its high price competitiveness and high technology maturity but has a disadvantage of low hydrogen density due to its relatively low performance. However, the performance can be improved using the Zero-Gap alkaline water electrolysis, and the porous transport layer (PTL) can be grafted to efficiently supply the electrolyte into the cell and emit the generated gas. In this dissertation, PTL composed of nickel foam, nickel mesh, and suspension mesh with different physical properties was grafted to alkaline water electrolysis cells to measure performance, and the relationship was analyzed by observing the change in performance according to the physical properties of PTL. Finally, in the case of SUS mesh PTL, the performance was especially superior in high current density, which facilitates material transfer, indicating that the SUSMES with the largest pore size and separated layers showed an advantage in terms of material transfer. Accordingly, it is seen that the gas generated through the reaction is smoothly emitted from the surface of the electrode, and thus the overall overvoltage is reduced, and the performance is improved. Although performance is improved by grafting PTL with optimal properties in alkaline water electrolysis, research on PTL in alkaline water electrolysis is still insufficient, so research on new materials or design of PTL structures is needed.