(590s) Innovative water management strategies for stable and efficient CO? electrolysis

CO₂ electrolysis offers a promising pathway to convert CO₂ into valuable chemicals such as carbon monoxide and hydrocarbons, which can serve as feedstocks for the chemical industry. This process has the potential to close the carbon cycle and pave the way for zero-emission synthetic fuels and value-added chemicals. However, current CO₂ electrolysis cells face several challenges that limit their efficiency and stability, many of which are related to water management within the cell.

Excess water (due to osmosis and pressure differences) can lead to flooding of the gas diffusion electrodes, preventing access for the gas. Conversely, insufficient water (due to reactions, electro-osmosis and heating) may cause electrolyte salt to precipitate and ion-exchange membranes to dry out, significantly increasing ohmic resistance or even leading to total cell failure.

We study configurations for CO2 electrolysis that provide water and electrolyte via a layer of micro-channels in the cell. We compare flow properties and electrochemical performance for different microchannel layers. Previous work in our group has already demonstrated successful integration of microchannels within an anion exchange membrane.1 The membrane with microchannels showed increased current densities compared to a similar membrane without channels, providing evidence for improved hydration. By maintaining the membrane-integrated hydration, we aim to suppress carbonate salt precipitation near the cathode, unlocking longer-term operational stability and maintaining low overpotential. Moreover, improved membrane hydration reduces ohmic voltage losses for improved CO2 to CO conversion efficiency.

Keywords:

Electrochemical fundamentals, Energy (Sustainability & Environment), Carbon management

1. Petrov, K. V. et al. Anion-exchange membranes with internal microchannels for water control in CO2 electrolysis. Sustainable Energy Fuels 6, 5077–5088 (2022).