High-Pressure Electrochemistry in Condensed Gases and Supercritical Fluids

Andrew Wong | 21-LW-057

Project Overview

The growing demand for renewable energy, spurred by the need to reduce reliance on foreign fossil-fuel imports, construct a resilient electricity grid, and address the mounting challenges of climate change, points toward a future of substantial electrification. Currently the major United States energy and chemical industries are dominated by large-scale thermochemical processes within power plants, refineries, and petrochemical facilities that rely on fossil-fuel combustion. This project aims set the stage for viable industrial alternatives to energy and materials production using high-pressure electrochemistry. Electrochemistry provides an electrified alternative for thermochemical processes by using electricity rather than heat to produce new chemicals. Performing electrochemistry at high-pressures is advantageous because both the chemical reactants and products are concentrated 100s or 1000s of times, dramatically decreasing the size, and therefore cost, of the reactor hardware.

This project started as an exploration of high-pressure carbon dioxide (CO2) electrochemistry, which has been known to produce chemicals such as carbon monoxide and ethylene, both foundational building blocks for common materials such as plastics and fuels. At sufficiently high pressures, CO2 becomes a supercritical fluid that approaches the density of water and is a highly concentrated reactant. This project explored this new system by three complementary avenues: 1. We designed and constructed a new high-pressure electrochemistry experimental setup to test these reactions at 1000 times atmospheric pressure. 2. We used thermodynamics to explore unique two- and three-materials interactions, creating new phase diagrams in the process. 3. We combined computational simulations to provide new insight into interactions happening at the molecular level. With these new techniques and insights, this project accomplished its goals of performing the Lab's first high-pressure electrochemical experiments, producing a range of unexpected small molecules in supercritical CO2, and has established a new experimental and computational platform for developing electrochemical reactions in a range of condensed gases.

Mission Impact

A key component of this project was to bring together two independent branches of the Lab together for the first time, namely historic expertise in high-pressure physics and a growing portfolio of projects in electrochemical conversion of small molecules. Elements of this project have helped seed efforts in several newly funded projects including lab-directed research and development (LDRD) and cooperative research and development agreements (CRADAs). This project produced a new high-pressure electrochemistry tool at the Lab which will be used for other electrochemistry projects. The growth of connections between experts in high-pressure physics and electrochemistry has allowed faster production of new tooling to support ongoing projects. The computational tools developed in this project have attracted the attention of researchers exploring planetary formation, providing an unexpected bridge to other experts. Additionally, this project supported three postdocs through conversion to staff scientists and supported a new-hire postdoc to the Lab. Overall, this project furthered the NNSA mission to develop science and technology tools and capabilities to meet future national-security challenges, particularly as they pertain to energy and materials, and provided important research progress directly connected to aims of the Department of Energy's Advanced Manufacturing Office and Office of Fossil Energy and Carbon Management.

Publications, Presentations, and Patents

Wong, A, and T. Moore. 2022. "Use of Organic Cosolvents to Enhance Water Solubility in CO2 for High Pressure CO2 Electroreduction." ROI IL-13737.

Wong, A, and T. Moore. 2022. "Spontaneous Phase Separation and Density Stratification to Facilitate High Pressure Electrochemical CO2 Reduction." ROI IL-13775.