Stacked additively manufactured electrochemical cell for reduction of carbon dioxide to ethylene

Ball, Keiran, Tacon, Christopher, Reeve, Sam, Perry, Samuel Charles and Leon, Carlos Ponce de (2019) Stacked additively manufactured electrochemical cell for reduction of carbon dioxide to ethylene. ECS Meeting Abstracts. (doi:10.1149/MA2019-02/18/984).

Abstract

An additively-manufactured two-cell stack is presented for the reduction of carbon dioxide to ethylene, forming part of a Horizon 2020 funded project, CO2EXIDE, which aims to recycle carbon dioxide in order to reduce greenhouse gas emissions1.

In this work we present a new compact flow field design, which allows for an easily expandable cell stack through the manufacture of additional identical bi-polar flow fields2. The flow fields are manufactured from 316L stainless steel using the 3D printing technique – Direct Metal Laser Sintering (DMLS). This allows them to simultaneously act as the flow fields and current collectors. The DMLS technology enables complex internal pipework, shown in figure 1, which allows a compact cell with no external pipework.

Our cell design is built around a membrane electrode assembly (MEA) (see figure 2), where CO2 is reduced at the cathode and water is oxidised at the anode3. The cathode is made from a copper nanoparticle catalyst, which is deposited onto a carbon gas diffusion layer. A nickel mesh is used as a catalyst for the anodic reaction. The flow fields were designed and optimised using the ANSYS Fluent 19.1 software in order to maximise residence time within the cell and ensure a similar pressure drop on each side of the MEA, which are essential to provide high reaction selectivity and to avoid pressure driven fluid transport across the proton exchange membrane respectively. Designing the flow field in this way allowed us to optimise our cell for both high ethylene yield and a long working life time (see figure 3 for the flow field pattern).

The finished assembly (see figure 4) was analysed for its ability to selectively reduce CO2 to ethylene. CO2 was flowed over the cathode at varying flow rates, and the outflow gas was collected for ex situ analysis by gas chromatography. This design is promising for the future development of CO2 as a carbon source for ethylene, as the stackable design makes this assembly more easily scalable for large scale operations.

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Contributors

Author: Samuel Charles Perry

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