Summary
- Researchers at Argonne National Laboratory demonstrated a novel method using NMR spectroscopy to characterize chemical evolution in battery cells
- The technique focuses on the chemical degradation in commercial-grade pouch battery cells during long periods of operation
- The study observed that trapped lithium silicides in the anode reduced the cell’s energy storage capacity
- Adding a magnesium salt to the electrolyte helped decrease the amount of trapped lithium silicides
- The NMR capability at Argonne can be used by battery researchers and manufacturers to study long-term battery evolution without opening them up
Article
Researchers at the DOE’s Argonne National Laboratory have developed a novel method using nuclear magnetic resonance (NMR) spectroscopy to study the chemical evolution inside battery cells over extended periods. The technique allows for the characterization of chemical degradation in commercial-grade pouch battery cells as they operate for prolonged durations. NMR spectroscopy utilizes the magnetic properties of atomic nuclei to analyze the chemical environments in a sample, providing valuable insights into the behavior of lithium atoms in battery cells.
In a study conducted at Argonne, researchers applied the NMR spectroscopy technique to observe the fate of lithium atoms in silicon-anode cells as they underwent charging, discharging, and periods of rest over seven months. The Cell Analysis, Modeling, and Prototyping facility at Argonne fabricated the cells using a process similar to commercial battery manufacturing. The study revealed that during charging, many lithium atoms became trapped in the anode, leading to reduced energy-storage capacity. Additionally, lithium atoms remained in the anode as lithium silicides during discharge, further depleting the available lithium for cycling the cells and reacting with the electrolyte.
One significant finding of the study was that the addition of a magnesium salt to the electrolyte resulted in a decrease in the amount of trapped lithium silicides. This discovery suggests the possibility of using different chemical additives, electrolyte formulations, and silicon materials to limit the formation of trapped lithium silicides in battery cells. Argonne’s new NMR capability offers battery researchers and manufacturers a powerful tool for studying the long-term evolution of battery systems without the need to open them up. The sensitivity of NMR spectroscopy to light elements like lithium, silicon, carbon, and hydrogen makes it particularly useful for investigating emerging battery technologies such as sodium-ion and solid-state batteries.
According to Baris Key, an Argonne chemist and co-author of the study, the application of NMR to batteries has been limited until now, but the new capabilities provided by Argonne’s research could make it essential for researchers and manufacturers studying battery performance over time. The study was supported by the DOE’s Vehicle Technologies Office and published in the Journal of Power Sources. The research team, including authors such as Marco Rodrigues, Sohyun Park, and Fulya Dogan Key, hopes that the findings will inform new strategies for enhancing battery performance and durability through improved understanding of chemical processes within battery cells. Argonne’s NMR methods could also be applied to investigate aging in other battery components such as cathodes and electrolytes.
Overall, the research conducted at Argonne National Laboratory showcases the potential of NMR spectroscopy for studying chemical degradation and evolution in battery cells over extended periods of operation. By closely examining the behavior of lithium atoms in silicon-anode cells, the researchers identified factors contributing to reduced energy-storage capacity and proposed potential solutions such as the use of magnesium salts in the electrolyte. The availability of this new NMR capability at Argonne offers a valuable resource for battery researchers and manufacturers seeking to enhance the performance and reliability of battery technologies through improved understanding of chemical processes occurring within battery systems.
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