Determination of Oxygen and Nitrogen in Graphite and Carbon-Based Battery Materials

Significance of the topic

The accurate determination of oxygen and nitrogen in graphite and carbon-based battery materials is critical for optimizing lithium-ion cell performance, safety and lifetime. Oxygen content affects lithium intercalation behavior, structural stability and parasitic reactions that influence energy density and cycle life. Nitrogen—often intentionally introduced by doping—modifies electronic conductivity, catalytic behavior and surface chemistry, impacting rate capability and electrode formation. Rapid, accurate elemental analysis supports raw material acceptance, process control, electrode development and failure analysis in battery R&D and manufacturing.

Goals and overview of the application note

This application note describes a validated workflow using the LECO ON836 (including ONH836) inert-gas fusion analyzer to quantify oxygen and nitrogen simultaneously in graphite and carbon-based battery powders and composite anode materials. Objectives include presenting measurement principles, recommended instrument parameters and sample handling, demonstrating typical analytical performance on representative materials, and outlining best practices for calibration and routine analysis.

Methodology

The method uses inert-gas fusion (impulse graphite-furnace combustion) with sequential detection by non-dispersive infrared (NDIR) cells for CO/CO2 and by a thermal conductivity (TC) detector for nitrogen after selective scrubbing. Key steps:

• Pre-weighed sample (typically ~0.10 g) is sealed in a nickel capsule and dropped automatically into a graphite crucible in the impulse furnace.
• High-temperature reaction with the graphite crucible converts oxygen in the sample to CO/CO2; liberated gases are swept by an inert carrier (helium recommended) through a mass flow controller and detectors.
• Initial NDIR measures CO/CO2; a heated reagent stage oxidizes residual CO to CO2 and H2 to H2O. A subsequent NDIR quantifies total CO2 (for oxygen determination) after correcting for conversions.
• CO2 and H2O are removed chemically, leaving nitrogen as the dominant analyte; nitrogen is quantified by a thermal conductivity detector.

Used instrumentation

• Instrument model: LECO ON836 (including ONH836 option) designed for simultaneous O and N measurement across a dynamic range.
• Detectors: NDIR cells for CO/CO2 detection and a Thermal Conductivity (TC) detector for nitrogen.
• Furnace: Impulse graphite crucible with automated sample drop and lower/upper electrode mechanisms.
• Accessories: 776-247 graphite crucibles, 502-822 nickel capsules, electrode tips (models 611-351-181 / 611-351-182), crucible and sample tweezers, five-place balance for low-mass samples.
• Carrier gas: Helium (recommended); Argon is an acceptable alternative.

Method parameters and operational notes

Summarized operational settings include automated sample drop, analysis delay ~30 s, nominal sample mass ~1.0000 g for some calibration steps but typical sample analysis uses ~0.10 g. Furnace power was operated in constant mode (example power settings reported: ~5200 W for oxygen runs and ~4750 W for nitrogen sequences; values may require adjustment depending on line voltage to avoid crucible burn-through). For samples with a high free-swelling index, reduced sample mass (~0.05 g or less) is recommended; use a five-place balance when weighing ≤0.05 g. Surface oxide removal was not applied in the reported runs. Safety: follow SDS for all reference materials and samples.

Calibration approach: linear calibrations forced through the origin were used for both oxygen and nitrogen. Certified reference materials included LECO LCRM iron powders and LCRM/LRM steel pins; calibration verification used secondary standards (JK47A iron powder, etc.). A minimum of three replicates per blank, calibration or sample replicate was recommended for blank setting and calibration/drift correction.

Typical results and discussion

Representative analyses on commercially sourced graphite and carbon-based anode materials produced the following key outcomes:

• Oxygen: Typical oxygen concentrations for evaluated graphite powders and carbon materials clustered around 0.30 wt% O (mean ≈ 0.30% with sample standard deviation ≈ 0.01 for the example dataset).
• Nitrogen: Nitrogen values were very low, on the order of 0.004–0.005 wt% N (mean ≈ 0.005% with standard deviation <0.001 in the provided dataset), demonstrating the methods capability to quantify trace N in carbon matrices.
• Mass reproducibility: Reported replicate masses and measured signals indicate good sample-handling precision; reduced-mass protocols were used for materials with high free-swelling behavior to avoid crucible disruption.
• Calibration and verification: Calibrations used certified LECO reference materials with verification by independent standards. Linear force-through-origin calibration was effective across the reported ranges.

Discussion points:

• The inert-gas fusion approach with sequential NDIR/TC detection provides robust separation of oxygen and nitrogen signals even in carbon-rich matrices where CO/CO2 background and CO oxidation stages must be carefully controlled.
• Sample morphology and swelling behavior can substantially affect analysis mass and furnace interaction; modifying sample mass and validating with replicate runs mitigates these effects.
• Instrument power and crucible selection/condition must be optimized to balance complete analyte release and crucible longevity.

Benefits and practical applications

• Simultaneous, high-throughput quantification of O and N supports routine quality control of active materials and feedstocks used in battery electrodes.
• Low detection capability for nitrogen enables monitoring of doping levels and unintentional N contamination relevant to electrical and electrochemical performance.
• Method supports material development workflows: rapid screening of doped carbons, evaluation of binder or coating contributions to heteroatom content, and batch-release testing in production environments.

Future trends and potential uses

• Tighter control of heteroatom content will be increasingly important as electrodes are engineered at nanoscale and as silicon/carbon composites gain market share; accurate O and N analytics will be integral to these developments.
• Integration with laboratory informatics and automated sample-handling will streamline high-throughput screening for new anode chemistries.
• Method refinements and alternative detection chemistries may push quantification limits lower, improving analysis of ultra-pure carbons and trace dopants.
• Expanded matrix-specific protocols (for SiOx-containing composites, high-swelling graphites or binder-rich powders) will broaden applicability across evolving battery material designs.

Conclusion

Inert-gas fusion analysis on the LECO ON836 platform provides a practical, reliable workflow for simultaneous oxygen and nitrogen determination in graphite and carbon-based battery materials. The combination of NDIR and TC detection, along with careful sample preparation, calibration with certified reference materials and appropriate furnace settings, yields precise and reproducible measurements appropriate for R&D and production quality control. Attention to sample mass selection and furnace power settings is necessary to accommodate material-specific behaviors such as free swelling and to protect crucibles.

References

• LECO Corporation application note: Determination of Oxygen and Nitrogen in Graphite and Carbon-Based Battery Materials, Form No. 203-821-717, REV0, 2026.
• Certified reference materials referenced: LECO LCRM and LRM series (e.g., 502-702 LCRM Iron Powder, 502-904 LCRM Steel Pin), and secondary standards (JK47A Iron Powder).
• Instrumentation: LECO ON836 / ONH836 series operator's instruction manual (for detailed parameter definitions and safety instructions).