Negative Muon Spin Rotation and Relaxation Study on Battery Anode Material, Spinel Li4Ti5O12
Negative Muon Spin Rotation and Relaxation Study on Battery Anode Material, Spinel Li4Ti5O12
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DOI：
10.1021/acs.jpcc.2c02055
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
I. Umegaki;K. Ohishi;T. Nakano;S. Nishimura;S. Takeshita;A. Koda;K. Ninomiya;M. K. Kubo;J. Su
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文献类型：
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作者：
I. Umegaki;K. Ohishi;T. Nakano;S. Nishimura;S. Takeshita;A. Koda;K. Ninomiya;M. K. Kubo;J. Su
为了研究锂离子在电池负极材料尖晶石Li4Ti5O12中的本征自扩散系数（DLiJ），使用粉末样品在100 - 400 K的温度范围内测量了负和正μ子自旋旋转和弛豫（μ ± SR）谱。注入的μ +离子位于O2-离子附近的间隙位置，形成O-H键，而注入的μ-离子主要被氧核俘获，形成μ子氧。众所周知，间隙部位的μ +在高温下会扩散。然而，μ子氧是不动的，直到尖晶石分解温度。用μ-SR（ν-）方法测得的场涨落率在200 K以上随温度升高而增加，热激活能为0.08（5）eV。ν-（T）曲线与μ + SR得到的ν +（T）曲线吻合得很好。因此，内部核磁场波动的起源被明确地确认为Li+扩散，即，μ +扩散的可能性被清楚地排除。在假设正四面体位置的Li+离子以无规行走的方式跃迁到八面体空位的条件下，由计算得到的ν ±估算出300 K时的DLiJ为8（2）× 10 - 12cm~2/s，Ea = 0.08 eV.
To study an intrinsic self-diffusion coefficient of Li+(DLiJ) in a battery anode material, spinel Li4Ti5O12, negative and positive muon spin rotation and relaxation (μ±SR) spectra were measured using a powder sample in a temperature range of 100–400 K. The implanted μ+in this study locates at an interstitial site near the O2–ion to form an O–H like bond, whereas the implanted μ–is mainly captured by an oxygen nucleus, resulting in muonic oxygen formation. The μ+at an interstitial site is known to diffuse at high temperatures. Nevertheless, the muonic oxygen is immobile until the spinel decomposition temperature. The field fluctuation rate determined with μ–SR (ν–) increased with increasing temperature above 200 K with a 0.08(5) eV thermal activation energy. The ν–(T) curve agreed well with the ν+(T) curve obtained with μ+SR. Thus, the origin of a fluctuation in the internal nuclear magnetic field was unambiguously confirmed as Li+diffusion, i.e., the possibility of μ+diffusion is clearly excluded. From the obtained ν±,DLiJwas estimated to be 8(2) × 10–12cm2/s at 300 K withEa= 0.08 eV, under the assumption that the Li+ions at the regular tetrahedral site jump to the vacant octahedral site with a random walk process.