In situ 7Li nuclear magnetic resonance study of the relaxation effect in practical lithium ion batteries

Kazuma Gotoh, Misato Izuka, Juichi Arai, Yumika Okada, Teruyasu Sugiyama, Kazuyuki Takeda, Hiroyuki Ishida

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Lithium ion cells comprising actual components of positive electrodes (LiCoO2, LiNixCoyAlz, and LiMn2O4) and negative electrodes (graphite and hard carbon) were assembled for in situ 7Li nuclear magnetic resonance (NMR) experiments. The 7Li NMR measurements of the cells revealed a ''relaxation effect'' after overcharging: a decrease of the signal assigned to Li metal deposited on the negative electrode surface by overcharging. The reduction of the Li metal signal was inversely proportional to the increase of the signal of lithium stored in carbon. Therefore, the effect was ascribed to absorption of deposited lithium into the carbon of negative electrodes. The effect, which occurred rapidly in a few hours, reached an equilibrium state at 8-15 h. The slight shift of deposited metal suggests that dendritic Li easily re-dissolved, although larger Li particles remained. A hard carbon electrode has a greater effect of Li metal relaxation than graphite electrodes do, which is explainable by the bufferable structure of the carbon. Results are expected to be important for the discussion of the state of lithium, and for safer battery design.

Original languageEnglish
Pages (from-to)380-387
Number of pages8
Issue number1
Publication statusPublished - 2014

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)


Dive into the research topics of 'In situ <sup>7</sup>Li nuclear magnetic resonance study of the relaxation effect in practical lithium ion batteries'. Together they form a unique fingerprint.

Cite this