Non-negative matrix factorization for 2D-XAS images of lithium ion batteries

Hiroki Tanimoto, Xu Hongkun, Masaishiro Mizumaki, Yoshiki Seno, Jumpei Uchiwada, Ryo Yamagami, Hiroyuki Kumazoe, Kazunori Iwamitsu, Yuta Kimura, Koji Amezawa, Ichiro Akai, Toru Aonishi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Lithium-ion secondary batteries have been used in a wide variety of purposes, such as for powering mobile devices and electric vehicles, but their performance should be improved. One of the factors that limits their performance is the non-uniformity of the chemical reaction in the process of charging and discharging. Many attempts have been made to elucidate the mechanism behind this reaction non-uniformity. In this paper, to detect non-uniformity in various physical properties from Co K-edge two-dimensional x-ray absorption spectroscopy (2D-XAS) images of lithium ion batteries, we propose a method that consists of one-sided orthogonal non-negative matrix factorization in combination with removal of the reference signal. The difference between x-ray absorption spectra acquired at different positions in the battery is very small. However, even in such a situation, our method can decompose the 2D-XAS data into different spatial domains and their corresponding absorption spectra. From the spectral decomposition of the obtained absorption spectra, we confirmed a transition-energy shift of the main peak as evidence for a change in the state of charge and also found spectral changes due to orbital hybridization in the decomposed spectral components.

Original languageEnglish
Article number115005
JournalJournal of Physics Communications
Issue number11
Publication statusPublished - 2021 Nov


  • 2D-XAS
  • Bayesian spectroscopy
  • Lithium Ion Secondary Battery
  • Non-Negative Matrix Factorization
  • Orbital Hybridization

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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