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• Comment: Can be incorporated into Nuclear magnetic resonance § Applications. Be sure to format your edits properly with inline citations, see WP:REFB for more help. Bobby Cohn (talk) 15:22, 13 November 2024 (UTC)

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NMR in battery

Nuclear Magnetic Resonance (NMR) is a powerful analytical tool for investigating the local structure and ion dynamics in battery materials. NMR provides unique insights into the short-range atomic environments within complex electrochemical systems such as batteries. Electrochemical processes rely on redox reactions, in which ⁷Li or ²³Na are often involved. Accordingly, their NMR spectroscopies are affected by the electronic structure of the material, which makes NMR an essential technique for probing the behavior of battery components during operation.

Applications of NMR in Battery Research
● Electrodes and Structural Transformations: During charge and discharge cycles, the materials in the anodes and cathodes undergo local structural transformations. These changes can be monitored using NMR by analyzing the signal's line shape, line intensity, and chemical shift.¹ These transformations are often not captured by X-ray diffraction techniques (providing long-range information),² making NMR indispensable for understanding the underlying mechanisms of energy storage.
● Metal Dendrite Formation: One of the challenges in lithium and sodium-based batteries is the formation of metal dendrites, which can lead to short circuits and catastrophic battery failure. In Situ NMR allows researchers to observe the formation of lithium or sodium dendrites in real time during battery cycling.³ Varying the cycling rates can also quantify the effect on dendrite formation, aiding in the development of strategies to suppress dendrite growth and reduce the risk of short circuits.
● Solid Electrolytes and Interfaces: Solid electrolytes, a key focus of next-generation battery research, often suffer from limited ion diffusion rates. NMR techniques can measure diffusivity in solid electrolytes, helping researchers understand how to enhance ion conductivity.⁴ Furthermore, NMR is used to study the Solid Electrolyte Interface (SEI), a layer that forms on the electrode surface and thus influences battery stability. Solid-state NMR (ssNMR) is particularly valuable for characterizing the composition and ion dynamics within the SEI layer due to its nondestructive testing capabilities.⁵

In Situ and Ex Situ NMR Techniques
NMR technology can be divided into two main experimental approaches in battery research: In Situ NMR and Ex Situ NMR.⁶ Each offers unique advantages depending on the research goals.
● In Situ NMR: In situ NMR enables real-time observation of chemical and structural changes in batteries while they are operating. This is particularly important for studying transient species that only exist under working conditions, such as certain intermediate reaction products. In situ NMR has become a critical tool for understanding processes like lithium and sodium plating and dendrite formation during battery cycling.³

Schematic of in situ NMR

● Ex Situ NMR: Ex situ NMR is used after the battery has been disassembled, allowing for high-resolution analysis of battery components. It is often employed to study a wide range of nuclei, including ¹H, ²H, ⁶Li, ⁷Li, ¹³C, ¹⁵N, ¹⁷O, ¹⁹F, ²⁵Mg, ²⁹Si, ³¹P, ⁵¹V, ¹³³Cs. Many of these nuclei are quadrupolar or present in low abundance, making them difficult to detect. However, ex situ NMR benefits from better sensitivity and narrower linewidths, which can be further improved by employing larger sample volumes, higher magnetic fields, or magic angle spinning (MAS).

See Also
Nuclear magnetic resonance
Nuclear magnetic resonance spectroscopy
X-ray diffraction
Solid-state nuclear magnetic resonance
Magic angle spinning

References
1. Pecher, O., et al., Materials’ Methods: NMR in Battery Research. Chemistry of Materials, 2017. 29(1): p. 213-242.
2. Key, B., et al., Real-Time NMR Investigations of Structural Changes in Silicon Electrodes for Lithium-Ion Batteries. Journal of the American Chemical Society, 2009. 131(26): p. 9239-9249.
3. Bhattacharyya, R., et al., In situ NMR observation of the formation of metallic lithium microstructures in lithium batteries. Nature Materials, 2010. 9(6): p. 504-510.
4. Uitz, M., et al., Ion dynamics in solid electrolytes for lithium batteries: Probing jump rates and activation energies through time-domain Li NMR. Journal of Electroceramics, 2017. 38: p. 142-156.
5. Ilott, A.J. and A. Jerschow, Probing Solid-Electrolyte Interphase (SEI) Growth and Ion Permeability at Undriven Electrolyte–Metal Interfaces Using 7Li NMR. The Journal of Physical Chemistry C, 2018. 122(24): p. 12598-12604.
6. Hu, J.Z., et al., In situ and ex situ NMR for battery research. Journal of Physics: Condensed Matter, 2018. 30(46): p. 463001.