In materials science, precise molecular characterization is crucial for enhancing material properties. Spectroscopic techniques have become essential tools in this field, offering non-destructive ways to explore material properties, structural integrity, and chemical composition.

Nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FT-IR) spectroscopy are essential analytical tools in materials science. These complementary techniques are widely employed in the research and development (R&D) of new materials, quality control (QC) of manufactured products, and the study of material behavior. 

NMR and FT-IR: Two sides of the same analytical coin

Each technique has unique strengths when used independently. FT-IR is relatively inexpensive to operate and provides rapid, reliable results, even when used by non-experts. It is particularly effective for identifying functional groups and characterizing chemical bonds within a sample. NMR offers detailed insights into molecular structures, interactions, and dynamic processes, making it indispensable for elucidating complex molecular systems and driving new product development.

Both techniques generate unique spectral "fingerprints" of materials, facilitating precise identification and comparison. NMR and FT-IR are applicable to a broad range of materials, including polymers, ceramics, metals, and composites, making them versatile tools in materials science.

When combined, NMR and FT-IR provide a more comprehensive understanding of a material's composition and characteristics. This integrated approach enables the detection of impurities, evaluation of material quality, and in-depth analysis of structural, chemical, and dynamic properties, offering a robust foundation for both research and industrial innovation.

Spectroscopic techniques have become essential tools in this field, offering non-destructive ways to explore material properties, structural integrity, and chemical composition.

NMR and FT-IR in the battery industry

NMR and FT-IR are essential techniques in the research and development of battery technologies. Both methods offer complementary insights into the chemical and structural properties of materials used in batteries, such as electrodes, electrolytes, and separators. 

NMR spectroscopy is a non-destructive technique used to characterize the molecular structure of samples in both solid-state and solution. It enables the study of the local environment of nuclei in battery components, which is crucial for understanding ion transport mechanisms, electrode-electrolyte interactions, and phase transitions during battery operation. It can monitor ion movement in the electrolyte, determine the state of charge or discharge of battery components, and reveal subtle changes in the crystal structure of electrodes during cycling. These insights are invaluable for optimizing battery design, improving energy density, charging speed, and life cycle.

FT-IR, on the other hand, is widely used for analyzing functional groups, chemical bonds, and surface characteristics, making it an excellent tool for monitoring the quality and integrity of battery materials, such as electrodesⁱ and electrolytes.ⁱⁱ

FT-IR helps identify functional groups and monitor chemical changes that occur during cycling or aging, which are critical to understanding battery performance and longevity. It is also useful in assessing the compatibility of various materials, such as polymer binders and liquid electrolytes, which can influence the overall efficiency and stability of a battery.ⁱⁱⁱ

When combined, FT-IR and NMR offer a comprehensive understanding of battery materials from both a molecular and structural perspective. FT-IR can provide information on the chemical environment and surface interactions, while NMR offers data on the behavior of materials at the atomic level. This combination of techniques allows for a more holistic view of battery performance, helping researchers to identify potential issues such as degradation, capacity fade, or inefficient ion transport. By leveraging both techniques, manufacturers can improve the reliability and efficiency of batteries, particularly in next-generation energy storage solutions such as solid-state batteries or lithium-sulfur batteries.

Benefits to the lab of using NMR and FT-IR 

Recent advancements in benchtop NMR technology have made it more accessible, reducing the barriers to entry with simplified workflows and bringing this powerful technique out of traditional research laboratories. Similarly, developments in handheld FT-IR instruments have expanded their use, allowing them to move beyond the laboratory and into field applications.

The integration of artificial intelligence (AI), machine learning (ML), lab automation, and cloud-based data management platforms has significantly impacted both NMR and FT-IR. These technologies enable the analysis and interpretation of sample spectra at a higher level, unlocking new insights into materials research by automating data processing, improving accuracy, and enabling faster decision-making.

Real world examples of NMR and FT-IR in use
 

FT-IR and NMR were combined to study lithium-ion batteries, focusing on a novel lithium replenishment strategy. The techniques demonstrated that dilithium squarate (Li₂C₄O₄) is chemically stable, air-resistant, and well-suited for use as a lithium source in lithium-ion batteries. These properties ensure consistent performance and long-term reliability in lithium replenishment strategies.^iv

Another application where FT-IR and NMR can be used in tandem is to provide comprehensive analyses of polymer structure and composition. FT-IR reveals the presence and type of chemical bonds in the polymer, whereas NMR provides information on the arrangement of atoms and the connectivity of chemical bonds.

In a paper by Worzakowska, NMR and FT-IR were used to confirm the structure and evaluate the conversion degree (DC) of the double bonds in the poly(citronellyl methacrylate)-co-poly(benzyl methacrylate) copolymers.^v Poly(methacrylates) are widely used in biomedicine, dentistry and nanotechnology as elements and components of many blends and compositions. The results from both FT-IR and NMR confirmed the high efficiency of the polymerization process and the formation of branched, cross-linked materials.

The combined use of solid-state NMR and FT-IR in a study by Rizzuto et al. highlights their synergistic benefits for characterizing mixed-matrix membranes (MMMs) for CO² capture.^vi Together, these techniques revealed that the CO² adsorption mechanism of the metal–organic framework (MOF) was preserved in the polymer matrix, contributing to the enhanced selectivity and permeability of the membrane. This integrated approach allowed for a comprehensive understanding of the MMM's performance, offering deeper insights than either technique alone.

A complete picture

FT-IR and NMR are powerful tools that can be used together to provide a more complete picture of the structure and properties of materials. By combining their strengths, researchers can gain valuable insights into the behavior and performance of materials. 

Automated, high-throughput FT-IR and NMR systems further accelerate the development of advanced materials, enabling in-line production monitoring and streamlining research workflows. These advancements are crucial for meeting the growing demand for green materials and energy-efficient solutions, ensuring their role as essential tools in the future of materials science. 

References

i. "Analysis of Electrode Surfaces by IR Laser Imaging." Bruker Optics. 2023.

ii. "In Situ FTIR Spectroelectrochemistry: Experimental Set-up for the Investigations of Solutes and Electrode Surfaces." Bruker Optics. 2021.

iii. Amaral MM, Real CG, Yukuhiro VY, et al. "In situ and Operando Infrared Spectroscopy of battery systems: Progress and opportunities." Journal of Energy Chemistry. 2023;81:472-491. doi:10.1016/j.jechem.2023.02.036

iv. Liu G, Wan W, Nie Q, et al. "Controllable long-term lithium replenishment for enhancing energy density and cycle life of lithium-ion batteries." Energy Environ Sci. 2024;17:1163-1174. doi:10.1039/d3ee03740a

v. Worzakowska M. "TG/DSC/FTIR/QMS analysis of environmentally friendly poly(citronellyl methacrylate)-co-poly(benzyl methacrylate) copolymers." Journal of Materials Science. 2023;58(4):2005-2024. doi:10.1007/s10853-022-08089-5