Study on Cycle Life of Lithium-Ion Batteries Using in Situ 7Li Solid-State Nuclear Magnetic Resonance
We have developed an in situ 7Li solid-state nuclear magnetic resonance (NMR) measurement and studied the reaction inside the LIBs without decomposition [1,2]. We applied this technique to the analysis of the battery cycle life. The Li intercalation in carbon (graphite intercalation compound, GIC) was monitored every 100 cycles during cycle tests that were performed at 10 and 25 °C with 0.5 and 1 C discharge rates, respectively. The cell was composed of a LiCoO2 positive electrode, a carbon negative electrode, and an organic electrolyte (ethylene carbonate (EC)/ethyl methyl carbonate (EMC) with 1 M LiPF6). Fig. 1 shows the spectra measured at 100% state of charge (SOC), a fully charged mode at 0.2 C constant-current and constant-voltage (CCCV), every 100 cycles at 25 °C.
- K. Gotoh, M. Izuka, J. Arai, Y. Okada, T. Sugiyama, K. Takeda, H. Ishida, Carbon, 79, 380 (2014).
- J. Arai, Y. Okada, T. Sugiyama, K. Gotoh, M. Izuka, K. Takeda, ECS Trans. 62(1), 159 (2014).