The origin of overpotential in lithium-mediated nitrogen reduction
O Westhead1, R Tort2, M Spry1
1Department of Materials, Imperial College London, UK. i.stephens@imperial.ac.uk.
Faraday Discussions
|April 24, 2023
Summary
Researchers developed a simple method to quantify voltage losses in lithium-mediated nitrogen reduction. This analysis reveals overpotential sources, aiding in the development of efficient nitrogen reduction systems.
Area of Science:
- Electrochemistry
- Materials Science
- Chemical Engineering
Background:
- Lithium-mediated nitrogen reduction systems have gained attention for ammonia synthesis.
- Quantifying overpotential and voltage losses in these systems remains challenging.
- Accurate potential measurements are crucial for system optimization.
Purpose of the Study:
- To develop a straightforward method for determining the Reversible Hydrogen Electrode (RHE) potential in lithium-mediated nitrogen reduction.
- To investigate the Nernst equation and identify sources of voltage losses.
- To enable direct comparison with other nitrogen reduction mechanisms.
Main Methods:
- Implementation of a simple method to measure RHE potential.
- Analysis of potential losses, including lithium ion solvation and solid electrolyte interphase resistive losses.
- Electrolyte optimization using LiClO4, ethanol, and tetrahydrofuran.
Main Results:
- A minimum overpotential of -3.59 ± 0.07 V vs. RHE was achieved.
- Faradaic efficiency was measured at 6.5 ± 0.2%.
- Key voltage loss contributors identified as Li+ solvation and SEI resistance.
Conclusions:
- The developed method accurately quantifies overpotential in lithium-mediated nitrogen reduction.
- Understanding voltage losses facilitates the design of more efficient electrochemical nitrogen fixation systems.
- This approach allows for standardized comparisons across diverse nitrogen reduction strategies.
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