Lithium diffusion in spinel Li4Ti5O12 and LiTi2O4

Abstract

Diffusion of Li + in (111) oriented thin films of the spinels Li 4 Ti 5 O 12 and LiTi 2 O 4 has been studied with 8 Li β-detected NMR in the temperature range between 5 and 310 K. In Li 4 Ti 5 O 12 , the spin-lattice relaxation rate (1/T 1) versus temperature shows a clear maximum around 100 K (=T max) which we attribute to magnetic freezing of dilute Ti 3+ local magnetic moments, consistent with the results of magnetization and muon spin relaxation (μ + SR) measurements. The decrease in 1/T 1 with temperature above T max indicates that Li + starts to diffuse with a thermal activation energy (E a) of 0.11(1) eV. In LiTi 2 O 4 , on the contrary, as temperature increases from 200 K, 1/T 1 increases monotonically up to 310 K. This suggests that Li also starts to diffuse above 200 K with E a = 0.16(2) eV in LiTi 2 O 4. Comparison with conventional Li-NMR on Li 4 Ti 5 O 12 implies that both β-NMR and μ + SR sense short-range Li motion, i.e., a jump diffusion of Li + to the nearest neighboring sites.

Pulsed Laser Deposited Films for Microbatteries

“…As-deposited films at a substrate temperature of 700 °C in a 6.6 Pa oxygen partial pressure exhibited a high initial capacity (~200 mAh·g −1 ) but poor stability [311]. Kumatani Studies of the electrochemical performance and kinetic behavior of PLD LTO films deposited on Pt/Ti/SiO2/Si substrates were reported by Deng et al [313]. Using an Li-rich target (i.e., excess 5 wt.…”

“…The energy barrier of the diffusion of lithium ions was estimated to be Ea = 0.11 eV in LTO (111)oriented PLD thin films (190 nm thick) grown on a spinel MgAl2O4 (111) substrate [314]. Studies of the electrochemical performance and kinetic behavior of PLD LTO films deposited on Pt/Ti/SiO 2 /Si substrates were reported by Deng et al [313]. Using an Li-rich target (i.e., excess 5 wt.% Li 2 O), the films annealed at 700 • C for 2 h in air were well-crystallized items with densely packed grains.…”

Recent Developments of Nanomaterials and Nanostructures for High‐Rate Lithium Ion Batteries

“…Quantitatively, the estimated activation energy barrier drops from 0.62 (x = 0) to 0.36 eV (x = 0.1). [137] Generally, both spin-lattice and spin-spin relaxation rate constants in NMR experiment can be used to study the shortrange motional processes at a timescale of ns to ms. [140] As an example, spin-lattice relaxation rate (1/T 1 ) was used to estimate the activation energy of lithium ion diffusion in thin films of Li 4 Ti 5 O 12 and LiTi 2 O 4 by 8 Li β-NMR within the temperature range from 5 to 300 K by Sugiyama et al [138] As shown in Figure 15b, the 1/T 1 change rate as a function of inverse temperature at low temperature levels (T < 100 K) is much more gentle than that at high temperature levels (T > 200 K), which suggests that two relaxation mechanisms within various temperature ranges (i. e., localised magnetic moments/lithium diffusion dominates at low/high temperature levels). The energy barrier (for lithium ions diffusing in Li 4 Ti 5 O 12 ) was estimated to be~0.11 eV by Figure 14.…”

Desorption reaction in MgH2 studied with in situ μ+SR

“…This indicates that the eld uctuation rate (n) is very rapid compared with the static width (D) due to H int , as in the case for Li-and Na-diffusion in battery materials. [37][38][39][40][41][42][43][44][45][46] In order to extract D and n from the m + SR data for the three samples, the ZF-and LF-m + SR spectra were tted by a combination of two dynamic Gaussian KT signals (G DGKT ) 57 and a timeindependent background signal coming from the muons stopping in the sample cell:…”

“…Indeed, there are still large discrepancies between experimental results and calculated predictions for hydrogen diffusion in MgH 2 . [31][32][33][34][35][36] We have therefore used m + SR to study H int in MgH 2 (where it arises mainly from the nuclear magnetic moment of 1 H), since the diffusion coefficients of Li + and Na + are estimated for many battery materials using the uctuation rate of H int detected with m + SR. [37][38][39][40][41][42][43][44][45][46] Due to the fact that the natural abundance of 25 Mg with I ¼ 5/2 is 10%, the m + SR spectrum caused by the m + s stopped in a Mg phase should be time independent, particularly above room temperature. Taking Remembering that m + behaves as a light isotope of H + in solids, 1,2 m + is expected to be mobile in any system where H is diffusing, regardless of the charge state of H. However, the differences between the diffusive behaviors observed by m + SR in the three MgH 2 samples imply that m + diffusion is not equivalent to H diffusion in MgH 2 .…”