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SUMMARY:Ion-Dynamics in Materials for Future Solid State Energy Devices
DTSTART:20130913T141500
DTSTAMP:20260407T101236Z
UID:44dbaa18e24d35bf3caaac2cb57f356e44dc01036636f5960de7c319
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Martin Mansson\, Laboratory for Quantum Magnetism (LQM) - 
 EPFL & Laboratory for Neutron Scattering (LNS) - PSI\nOne of the most impo
 rtant scientific problems to solve for our modern society is how to conver
 t and store clean energy. In order to accomplish a paradigm shift in this 
 field\, we need to understand the fundamental dynamical processes that gov
 ern the transfer of energy on an atomic scale. For future energy devices l
 ike solid-state batteries (SSB) as well as solid-oxide fuel cells (SOFC)\,
  this means understanding and controlling the complex mechanisms of ion di
 ffusion in solid matter. Only recently\, developments of state-of-the-art 
 large scale experimental facilities e.g. neutron/muon spallation sources a
 s well as free electron lasers\, have opened new possibilities for studyin
 g such intrinsic material properties in a straightforward manner. I have i
 n a collaboration with Toyota Central Research and Development Laboratorie
 s in Japan\, developed a novel method that utilizes the muon-spin rotation
 /relaxation (m+SR) technique to probe the microscopic ion self-diffusion c
 onstant (Dion) with high accuracy [1]. I will give a brief introduction to
  the method itself as well as summarize our extensive m+SR studies of Li-i
 on diffusion in a wide range of battery cathode materials [2-6].\nIn the f
 ield of rechargeable batteries\, strong interest has recently been raised 
 to find a replacement for traditional Li-ion technology. The main reason i
 s that such batteries are rather expensive and in addition the extraction 
 of lithium metal is problematic from an environmental point of view due to
  its high reactivity and relatively low abundance in the Earth’s crust (
 only 20 ppm). One option to avoid these drawbacks may be to replace lithiu
 m (Li) with sodium (Na) in the electrode materials. Sodium is similar to l
 ithium in its chemical properties\, but approximately 1000 times more abun
 dant in the Earth’s crust (26’000 ppm) as well as in the form of salt 
 (NaCl) in normal seawater (15’000 ppm). This makes sodium based batterie
 s potentially more environmental friendly and easier to recycle as well as
  up to five times less expensive.\nCurrently the most common Li-ion cathod
 e material is LiCoO2\, where the Na-analog consequently is NaCoO2\, making
  this compound a logical first step towards the development of Na-ion batt
 eries. To understand the Na-ion diffusion process in this material\, we ha
 ve performed high-resolution neutron diffraction (ND) measurements as a fu
 nction of temperature. Our data display a two-step "melting" of the Na-ion
  planes\, involving an intriguing crossover from 1D-to-2D Na-diffusion cha
 nnels [7]. Further\, it is evident that the onset and evolution of ion-dif
 fusion is intrinsically linked to a series of subtle structural transition
 s\, which unlocks the diffusion pathways. Finally\, we have also performed
  m+SR [8] and pressure-dependent neutron scattering measurements [9]\, whi
 ch reveal novel and functional possibilities for tuning Na-ion diffusion u
 sing lattice-strains. In summary\, our current research has established a 
 novel and detailed insight into the ion-diffusion mechanisms in these comp
 ounds. This allows us to actively consider targeted tuning and smart desig
 n of energy related materials for the use in future solid state devices wi
 th optimized performance.
LOCATION:PH L1 503 http://plan.epfl.ch/?room=PHL1503
STATUS:CANCELLED
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