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Realizing the Ultimate Thermal Stability of a Lithium-Ion Battery Using Two Zero-Strain Insertion Materials

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journal contribution
posted on 26.09.2018, 00:00 by Takeshi Uyama, Takao Inoue, Kazuhiko Mukai
Thermal runaway of lithium-ion batteries has been of great concern in light of their anticipated widespread use in future information devices and in support of an environmentally friendly society. Although the utilization of a fire retardant liquid electrolyte or a solid-state electrolyte has been proposed as a possible solution thus far, the possibility of thermal runaway at elevated temperatures above ∼200 °C continues to exist. In this study, we focused on materials for the positive electrode, spinel-structured LiCoxMn2–xO4 (LCMO) with 0 ≤ x ≤ 1, because of their thermal stability and “zero-strain” characteristics particularly for the x = 1 composition. Here, the term zero-strain refers to lattice parameters that undergo changes that are negligibly small during the charge and discharge reactions. Differential scanning calorimetry clarified that the x = 1 sample exhibited the most optimal thermal stability among the LCMO samples investigated, and that the total heat generation of the LCMO­(x = 1)|Li7La3Zr2O12|Li­[Li1/3Ti5/3]­O4(LTO) battery was ∼0 kJ mol–1 up to 480 °C, i.e., ultimate thermal stability. In addition, because of the zero-strain characteristics of LTO, the combination of LCMO­(x = 1) and LTO leads to an ideal battery that does not experience battery rupture, explosion, or leakage. Details of the thermal stability of the LCMO samples with 0 ≤ x ≤ 1 and necessary conditions for the ultimate thermal stability are discussed.