Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells

Merve Öztürk Kırkar

doi:10.29130/dubited.1967576

EN TR

Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells

Abstract

Thermal runaway is a critical safety concern in lithium-ion batteries, particularly because cathode chemistry and state of charge directly influence the severity of thermal abuse behavior. The present study performs a multivariate statistical analysis of thermal abuse behavior for commercial 21700-format cylindrical cells for five state-of-charge (SOC) levels (0%, 30%, 60%, 80%, 100%) and cathode chemistries (LFP, NMC, NCA-HEI, NCA-HEII, NCA-HP) using accelerating rate calorimetry data. The extracted thermal metrics are maximum temperature, thermal runaway onset temperature, self-heating onset temperature, and maximum heating rate. Two-way ANOVA with partial eta-squared (η_p^2) effect sizes assert significant main effects of SOC and chemistry, alongside a dominant chemistry and SOC interaction for thermal runaway onset temperature (η_p^2 = 0.99, p < 0.001). Non-parametric Kruskal–Wallis tests confirm the parametric findings, indicating robustness to distributional assumptions. A novel data-driven Thermal Risk Index (TRI) is developed employing principal component analysis-derived weights, with the first two principal components together explaining 94.1% of the total variance. The TRI shows a moderate monotonic dependence on SOC (Spearman's ρ = 0.480, p < 0.001), supporting its physical interpretation. Under fully charged conditions, NCA-HEI cells show the highest mean TRI (78.6), markedly exceeding LFP (33.4), a 2.4-fold difference between the most and least hazardous chemistries. These results quantify the chemistry-dependent safety hierarchy under operational extremes and propose an interpretable framework for comparative thermal risk assessment.

Keywords

Accelerating rate calorimetry, Cathode chemistry, Lithium-ion battery, State of charge, Thermal Risk Index

Supporting Institution

This research received no external funding.

Ethical Statement

This study does not involve human or animal participants. All procedures followed scientific and ethical principles, and all referenced studies are appropriately cited.

Thanks

The author does not wish to acknowledge any individual or institution.

Abstract

Lityum-iyon batarya uygulamalarında, özellikle elektrikli araçlarda, termal kaçak kritik bir güvenlik sorunu olup katot kimyası seçimi tehlike potansiyelini doğrudan etkilemektedir. Bu çalışmada, ticari 21700 tipi silindirik hücrelerin termal zorlanma koşullarındaki davranışı, beş farklı şarj durumu (SOC) seviyesi (%0, %30, %60, %80 ve %100) ve beş farklı katot kimyası (LFP, NMC, NCA-HEI, NCA-HEII ve NCA-HP) için hızlandırılmış oran kalorimetrisi verileri kullanılarak çok değişkenli istatistiksel yöntemlerle analiz edilmiştir. Analiz kapsamında maksimum sıcaklık, termal kaçak başlangıç sıcaklığı, kendiliğinden ısınma başlangıç sıcaklığı ve maksimum ısınma hızı olmak üzere dört termal metrik belirlenmiştir. Kısmi eta-kare (η_p^2) etki büyüklükleri ile birlikte uygulanan iki yönlü ANOVA sonuçları, SOC ve katot kimyasının anlamlı ana etkilerinin yanı sıra termal kaçak başlangıç sıcaklığı üzerinde baskın bir kimya–SOC etkileşimi olduğunu göstermiştir (η_p^2= 0,99, p<0,001). Parametrik olmayan Kruskal–Wallis testleri, parametrik bulguları destekleyerek sonuçların dağılım varsayımlarına karşı dayanıklı olduğunu ortaya koymuştur. Ayrıca, temel bileşen analizi ile türetilen ağırlıklar kullanılarak veri odaklı yeni bir Termal Risk İndeksi (TRI) geliştirilmiş; ilk iki temel bileşenin toplam varyansın %94,1’ini açıkladığı belirlenmiştir. TRI, SOC ile orta düzeyde monoton bir ilişki göstermiştir (Spearman ρ=0,480, p<0,001); bu durum indeksin fiziksel yorumlanabilirliğini desteklemektedir. Tam şarj koşullarında NCA-HEI hücreleri en yüksek ortalama TRI değerini (78,6) sergilemiş ve LFP hücrelerinden (33,4) belirgin biçimde daha yüksek risk göstermiştir; bu durum en yüksek ve en düşük tehlike düzeyine sahip kimyalar arasında 2,4 katlık bir fark olduğunu ortaya koymaktadır. Elde edilen sonuçlar, operasyonel uç koşullar altında katot kimyasına bağlı güvenlik hiyerarşisini nicel olarak ortaya koymakta ve karşılaştırmalı termal risk değerlendirmesi için yorumlanabilir bir çerçeve sunmaktadır.

Keywords

Hızlandırılmış oran kalorimetrisi, Katot kimyası, Lityum-iyon batarya, Şarj durumu, Termal Risk İndeksi, Termal kaçak

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Details

Primary Language

English

Subjects

Energy Generation, Conversion and Storage (Excl. Chemical and Electrical)

Journal Section

Research Article

Authors

Merve Öztürk Kırkar ^*
0000-0002-4414-0916
Türkiye

Publication Date

October 23, 2026

Submission Date

June 9, 2026

Acceptance Date

August 31, 2026

Published in Issue

Year 2026 Volume: 14 Number: 4

DOI

https://doi.org/10.29130/dubited.1967576

IZ

https://izlik.org/JA93KK57TB

APA

Öztürk Kırkar, M. (2026). Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells. Duzce University Journal of Science and Technology, 14(4), 1163-1175. https://doi.org/10.29130/dubited.1967576

AMA

1.Öztürk Kırkar M. Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells. DUBİTED. 2026;14(4):1163-1175. doi:10.29130/dubited.1967576

Chicago

Öztürk Kırkar, Merve. 2026. “Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells”. Duzce University Journal of Science and Technology 14 (4): 1163-75. https://doi.org/10.29130/dubited.1967576.

EndNote

Öztürk Kırkar M (October 1, 2026) Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells. Duzce University Journal of Science and Technology 14 4 1163–1175.

IEEE

[1]M. Öztürk Kırkar, “Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells”, DUBİTED, vol. 14, no. 4, pp. 1163–1175, Oct. 2026, doi: 10.29130/dubited.1967576.

ISNAD

Öztürk Kırkar, Merve. “Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells”. Duzce University Journal of Science and Technology 14/4 (October 1, 2026): 1163-1175. https://doi.org/10.29130/dubited.1967576.

JAMA

1.Öztürk Kırkar M. Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells. DUBİTED. 2026;14:1163–1175.

MLA

Öztürk Kırkar, Merve. “Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells”. Duzce University Journal of Science and Technology, vol. 14, no. 4, Oct. 2026, pp. 1163-75, doi:10.29130/dubited.1967576.

Vancouver

1.Merve Öztürk Kırkar. Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells. DUBİTED. 2026 Oct. 1;14(4):1163-75. doi:10.29130/dubited.1967576

Statistical Analysis of Cathode Chemistry and State-of-Charge Effects on Thermal Runaway Behavior of Type 21700 Lithium-Ion Cells

Abstract

Keywords

Supporting Institution

Ethical Statement

Thanks

Abstract

Keywords

References

Details

Primary Language

Subjects

Journal Section

Authors

Publication Date

Submission Date

Acceptance Date

Published in Issue

DOI

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