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Negative Muon Spin Rotation and Relaxation Study on Battery Anode Material, Spinel Li4Ti5O12
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2022-06-17 , DOI: 10.1021/acs.jpcc.2c02055
Izumi Umegaki 1 , Kazuki Ohishi 2 , Takehito Nakano 3 , Shoichiro Nishimura 1 , Soshi Takeshita 1 , Akihiro Koda 1 , Kazuhiko Ninomiya 4 , M. Kenya Kubo 5 , Jun Sugiyama 2, 6
Affiliation  

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 μSR (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±, DLiJ was estimated to be 8(2) × 10–12 cm2/s at 300 K with Ea = 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.

中文翻译:

电池负极材料尖晶石Li4Ti5O12的负介子自旋和弛豫研究

为了研究电池负极材料中 Li + ( D Li J )的固有自扩散系数,使用粉末样品测量了尖晶石 Li 4 Ti 5 O 12、负和正 μ 子自旋旋转和弛豫 (μ ± SR) 光谱在100-400 K的温度范围内。本研究中注入的μ +位于O 2-离子附近的间隙位置形成O-H状键,而注入的μ -主要被氧核捕获,导致介子氧的形成。μ +已知在间隙位点处会在高温下扩散。然而,介子氧在尖晶石分解温度之前是固定的。用 μ - SR (ν - )确定的场波动率随着温度升高到 200 K 以上而增加,热活化能为 0.08(5) eV。ν - ( T ) 曲线与使用 μ + SR获得的 ν + ( T ) 曲线非常吻合。因此,明确地确认了内部核磁场波动的起源是Li +扩散,即明确排除了μ +扩散的可能性。从获得的 ν ± , DLi J在 300 K 时估计为 8(2) × 10 –12 cm 2 /s, E a = 0.08 eV,假设常规四面体位点的 Li +离子随机跳到空置八面体位点行走过程。
更新日期:2022-06-17
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