Structure & Dynamics in Energy Materials using Muons & Neutrons

In order to obtain a paradigm shift in sustainable energy storage and conversion a new generation of materials needs to be realized. An important step will be to obtain a deeper understanding and control of the underlying structural and dynamic mechanisms related to the operational cycles within the device. Only recently, developments of state-of-the-art large scale experimental facilities i.e. neutron/muon spallation sources as well as synchrotron and free electron lasers, have opened new possibilities for studying such intrinsic material properties on the atomic scale in a straightforward manner. In a collaboration between academia and industry (Toyota CRDL) we have developed a novel and unique method that utilizes the muon-spin rotation/relaxation (m+SR) technique to directly probe the microscopic ion self-diffusion constant (Dion) with high accuracy [1] in both bulk materials as well as in thin films and interfaces. I will give a brief introduction to the method itself as well as summarize our extensive studies of microscopic ion diffusion in a wide range of energy related materials [2,3]. Further, more detailed results will be presented for one selected Na-ion material where we have conducted extensive studies using μ+SR [2], neutron powder diffraction (NPD) [4] and quasi-elastic neutron scattering (QENS) [5] as a function of temperature and chemical composition. Our results show unique details of the diffusion processes in these compounds. One example is how the Na-ion diffusion paths evolve from quasi-1D to fully 2D as a function of temperature and that such evolution is directly linked to subtle structural changes that unlock the diffusion channels. Finally, novel results from inelastic neutron scattering (INS) will be presented that reveal how surface phonons can tune device performance in nano-structured energy materials [6,7].

Fig. 1: (a) Rechargeable battery (b) Layered electrode material (c) Novel Q1D diffusion channels in NaxCoO2 (c) Activation energies (Ea) for Na-ion diffusion extracted from our μ+SR experiments.


[1] J. Sugiyama, M. Månsson, et al., Phys. Rev. Lett. 103, 147601 (2009)

[2] M. Månsson and J. Sugiyama, Ph. Scr. 88, 068509 (2013)

[3] J. Sugiyama, M. Månsson, et al., Phys. Rev. B 85, 054111 (2012)   +   Phys. Rev. B 92, 014417 (2015)

[4] M. Medarde, J. Sugiyama, M. Månsson, F. Juranyi, et al., Phys. Rev. Lett. 110, 266401 (2013)

[5] F. Juranyi, M. Månsson, et al., EPJ Web Conf. 83, 02008 (2015)

[6] Bozyigit, Wood, et al., Nature 531, 618 (2016)

[7] P. Benedek, M. Månsson, V. Wood, et al., Sustainable Energy & Fuels [RSC] (2019) – Accepted for publication


This research is funded by Marie Skłodowska-Curie Action: European Commission and Swedish Research Council, VR (Dnr. 2014-6426), a VR neutron project grant (Dnr. 2016-06955), Swedish Foundation for Strategic Research (SSF-SwedNess), and Carl Tryggers Foundation (CTS-16:324).