Thermal stability analysis of LiNi0.8Mn0.1Co0.1O2/graphite–SiO and LiNi0.8Mn0.1Co0.1O2/lithium cells using differential scanning calorimetry

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Thermal stability analysis of LiNi0.8Mn0.1Co0.1O2/graphite–SiO and LiNi0.8Mn0.1Co0.1O2/lithium cells using differential scanning calorimetry

著　者
Kazuki Chiba, Masahiro Ota
収　録
Journal of Energy Storage 129 (2025) 117196
発　行
2025年9月
要　旨
Lithium metal batteries pose safety challenges owing to thermal runaway triggered by lithium dendrite formation and exothermic reactions. Graphite–silicon monoxide (Gr–SiO) anodes represent a compromise between the high capacity of lithium metal and the thermal reliability of graphite. This study analyzed the thermal stability of full cells comprising an NCM811 cathode and either a Gr–SiO or a lithium metal anode using differential scanning calorimetry (DSC). Scanning electron microscopy revealed morphological changes in the Li anode retrieved from a fully charged cell, suggesting increased surface reactivity. DSC indicated heating-rate-dependent shifts in exothermic peak temperatures, which was consistent with thermal decomposition kinetics and confirmed the reliability of the DSC measurements. Compared with NCM811/Li cells, exothermic reactions near 110 °C—primarily attributed to the lithium and carbonate-based electrolyte—were suppressed in NCM811/Gr–SiO cells, which improved the thermal stability. These results were validated by accelerating rate calorimetry, which confirmed a higher thermal runaway onset temperature for the NCM811/Gr–SiO cell than for the NCM811/Li cell. This study provides insights into the thermal stability of lithium-based batteries.

Speaker

千葉 一毅
千葉 一毅 / Kazuki Chiba

その他 執筆論文（共著含む）

Comparison between hard carbon and natural graphite using the thermal safety diagrams of lithium-ion batteries

著　者
Kazuki Chiba, Masahiro Ota
収　録
Journal of Energy Storage 48 (2022) 104010
発　行
2022年1月
要　旨
For the thermal safety of lithium-ion batteries (LIBs), it is important to consider the calorific value (Q), the onset temperature and time of the thermal runaway. Thus far, the onset temperature and time have been estimated for well-known materials using a thermal safety diagram. However, little attention has been paid to the hard carbon (HC) and natural graphite (NG) structures incorporated in a cell. In this study, the calorific values (Q) per unit energy density of cells with LiNi0.8Co0.1Mn0.1O2 (NCM811) as the cathode and HC and NG as the anodes were compared and found to be similar. The structures of these carbon materials were identified using powder X-ray diffraction. The surface on the anode was analyzed using X-ray photoelectron spectroscopy. Open current voltage (OCV) measurements of the cells during heating were also carried out. Furthermore, the obtained diagrams showed that NCM811/HC has a delayed onset time for the thermal runaway compared to NCM811/NG. These results will help in reducing the Q and reaction rates by controlling the OCV of the cell, thereby leading to LIBs with improved thermal safety properties.

Thermal safety diagram for lithium-ion battery using single-crystal and polycrystalline particles LiNi0.8Co0.1Mn0.1O2

著　者
Kazuki Chiba, Akihiro Yoshizawa, Yuji Isogai
収　録
Journal of Energy Storage 32 (2020) 101775
発　行
2020年10月
要　旨
Thermal runaway of lithium-ion battery (LIB) depends not only on the chemical composition of cathode materials but also on grain boundary. However, despite many studies on thermal stability of cathode materials to date, few safety diagrams of thermal runaway in full cells have been reported. In this study, the thermal safety diagram is compared in the full cell by using single-crystal and polycrystalline particles LiNi0.8Co0.1Mn0.1O2 (NCM811) as cathode material and natural graphite (NG) as anode material. A thermal safety diagram is made using a differential scanning calorimetry (DSC) by using an all-inclusive cell, which consists of all LIB components. Since a thermal runaway reaction is a series of elementary reactions, it is determined using the Friedman differential isoconversional method. Thermal runaway prediction results obtained using DSC data are verified using an acceleration rate calorimeter (ARC). The prediction results nearly match the verification results of ARC measurements, and it is clarified that the full cell using single-crystal particles NCM811 as the cathode material has higher thermal safety than that using polycrystalline particles NCM811.

A novel synthetic route of micrometer-sized LiCoMnO4 as 5 V cathode material for advanced lithium ion batteries

著　者
Kazuki Chiba, Yuki Hamada, Hiroshi Hayakawa, Naoki Hamao, Kunimitsu Kataoka, Mikito Mamiya, Norihito Kijima, Naoya Ishida, Yasushi Idemoto, Junji Akimoto
収　録
Solid State Ionics 333 (2019) 9-15
発　行
2019年1月
要　旨
We synthesized micrometer-sized LiCoMnO4 with spinel structure by heating ion-exchanged LixCo0.5Mn0.5O2 with O6-type layered rocksalt structure at 600 °C. In this synthetic route, we first synthesized micrometer-sized NaxCo0.5Mn0.5O2 with P2-type layered rocksalt structure at 900 °C. Then, we prepared O6-LixCo0.5Mn0.5O2 by ion-exchange of Na+ for Li+ using LiNO3 at 280 °C The structural transformation from layered rocksalt to spinel structure was confirmed at about 600 °C by the DTA curve. The average particle size of about 5 μm was almost the same as that of the starting P2-NaxCo0.5Mn0.5O2. The discharge capacity–voltage curves of the present LiCoMnO4 showed a maximum discharge capacity of about 105 mA h g−1 between 3.0 and 5.2 V vs. Li/Li+ at 25 °C, in spite of large micrometer-sized particles. We believe that micrometer-sized LiCoMnO4 would be important as one of 5 V cathode materials to achieve its higher compressed density of the electrode for advanced lithium ion batteries (LIBs), such as all solid-state LIB application.

Characterization of NaxLi0.67+yNi0.33Mn0.67O2 as a positive electrode material for lithium-ion batteries

著　者
Kazuki Chiba, Masahiro Shikano, Hikari Sakaebe
収　録
RSC Advances 8 (2018) 26335
発　行
2018年6月
要　旨
The relationship between the charge–discharge properties and crystal structure of NaxLi0.67+yNi0.33Mn0.67O2 (0.010 ≤ x ≤ 0.013, 0.16 ≤ y ≤ 0.20) has been investigated. Li/NaxLi0.67+yNi0.33Mn0.67O2 cells exhibit gradually sloping initial charge and discharge voltage–capacity curves. The initial charge capacity increased from 171 mA h g−1 for thermally-treated Na0.15Li0.51Ni0.33Mn0.67O2 to 226 mA h g−1 for Na0.010Li0.83Ni0.33Mn0.67O2 with an increase in the Li content. The initial maximum discharge capacity was 252 mA h g−1 in the case of Na0.010Li0.83Ni0.33Mn0.67O2 between 4.8 and 2.0 V at a fixed current density of 15 mA g−1 (0.06 C) at 25 °C. The predominance of the spinel phase leads to the high initial discharge capacity of Na0.010Li0.83Ni0.33Mn0.67O2. This study shows that chemical lithiation using LiI is effective to improve the electrochemical properties.

NaxLi0.7−xNi1−yMnyO2 as a new positive electrode material for lithiumion batteries

著　者
Kazuki Chiba, Noboru Taguchi, Masahiro Shikano, Hikari Sakaebe
収　録
Journal of Power Sources 311 (2016) 103-110
発　行
2016年2月
要　旨
In this study, a new class of contenders for high-voltage and high-capacity positive electrode materials with the composition NaxLi0.7 − xNi1 − yMnyO2 (0.03 < x ≤ 0.25, 0.5 ≤ y ≤ 0.8) was synthesized by thermal treatment; these positive electrode materials synthesized by Na+/Li+ exchange using P3-Na0.7Ni1 − yMnyO2 (0.5 ≤ y ≤ 0.8) as the precursor exhibited a mixture of layered and spinel structures. The (dis)charge voltage-capacity curve of materials with these compositions significantly varied according to the residual Na and Mn content. Notably, HT- NaxLi0.7 − xNi1 − yMnyO2 (x = 0.093, y = 0.67) exhibited a maximum discharge capacity of 261 mA h g−1 at an average voltage of 3.36 V at 25 °C (between 2.0 and 4.8 V), which translates to an energy density of 943 W h kg−1. The obtained electrochemical performance is rationalized by the phase fractions of layered and spinel structures, which is triggered by the residual Na and Mn content in NaxLi0.7 − xNi1 − yMnyO2.

Synthesis and electrochemical properties of Li2/3Ni1/3Mn2/3O2 as a novel 5 V class positive electrode material for lithium-ion batteries

著　者
Kazuki Chiba, Masahiro Shikano, Hikari Sakaebe
収　録
Journal of Power Sources 304 (2016) 60-63
発　行
2015年11月
要　旨
A lithium nickel manganese oxide, O3-Li2/3Ni1/3Mn2/3O2, is synthesized from the precursor, P3-Na2/3Ni1/3Mn2/3O2, by a Na+/Li+ ion exchange reaction using molten salt. Post-heating at 300, 400, 500, 600, and 700 °C is carried out for 5 h in air. The products are characterized by powder XRD, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), SEM, 6Li-magic-angle-spinning-NMR, and electrochemical measurements. The charge/discharge profiles of O3-Li2/3Ni1/3Mn2/3O2, thermally treated at 500°C, show a high-potential plateau region at 4.8 V. Furthermore, sloping voltage profiles are observed at an average voltage of 3.21 V. An initial discharge capacity of 257 mA h g−1 is obtained between 2.0 and 4.8 V with a current density of 15 mA g−1 at 25°C. This capacity corresponds to 0.90 electron transfers per formula unit. This study shows that Post-heating of O3-Li2/3Ni1/3Mn2/3O2 is effective to improve its electrochemical properties.