Li Diffusion inLixCoO2Probed by Muon-Spin Spectroscopy

Abstract

The diffusion coefficient of Li+ ions (D(Li)) in the battery material LixCoO2 has been investigated by muon-spin relaxation (mu+SR). Based on experiments in zero and weak longitudinal fields at temperatures up to 400 K, we determined the fluctuation rate (nu) of the fields on the muons due to their interaction with the nuclear moments. Combined with susceptibility data and electrostatic potential calculations, clear Li+ ion diffusion was detected above approximately 150 K. The D(Li) estimated from nu was in very good agreement with predictions from first-principles calculations, and we present the mu+SR technique as an optimal probe to detect D(Li) for materials containing magnetic ions.

Insight into lithium transport in lithium nitridometallate battery materials from muon spin relaxation

“…4 In contrast, Sugiyama et al 3 found an activated ν, coupled with decrease in Δ for a muon forming a hydrogen-like bond to oxygen in LixCoO2. Only the contribution which arises from dipolar interactions with 6 Li or 7 Li nuclei is narrowed by Li + diffusion.…”

“…1 However, muon spin relaxation (µSR) has been suggested recently as an alternative means of studying Li + transport in these circumstances. [2][3][4] In µSR experiments 100% spin polarized muons are implanted into materials where they thermalize, allowing the measurement of local magnetic fields. The radioactive decay of the muons results in the emission of positrons along the spin polarization direction which are detected by a set of scintillators arranged around the sample.…”

Ion Diffusion in Solids Probed by Muon-Spin Spectroscopy

“…This is a highly unsatisfactory situation, since D Li is one of the primary parameters that govern the charge and discharge rate of a Li-ion battery, particularly in the case of future solid state batteries. We have, therefore, attempted to measure D Li for layered lithium-transition-metal-oxides with µ + SR since 2005 [14][15][16][17][18][19][20]. Muons do not feel fluctuating magnetic moments at high T , but instead sense the change in nuclear dipole field due to Li diffusion.…”

Probing magnetic order in LiMPO4(M=Ni, Co, Fe) and lithium diffusion in LiBaker1, Franke2, Pratt3 et al. 2011Phys. Rev. B446300View full textAdd to dashboardCite

“…As well as being a sensitive probe of magnetic ordering, 24,25 µSR provides a means of investigating diffusion processes of both the muon 26 and other species that perturb its environment. 27 Lithium diffusion is a process that provides such a perturbation and µSR has now been applied to studying it in a wide range of battery cathode materials: Li 30 Li 3−x−y Ni x N, 31 , Li x CoO 2 , 27,32 and LiNiO 2 . 33 Of these, the studies on Li x CoO 2 have been the most extensive and found that the lithium diffusion rate in this compound is well suited to the timescale probed by µSR.…”