大型放射光施設 SPring-8

Speaker : Dr. Bernardo Barbiellini

Language : ENGLISH

Affiliation : Department of Physics, Northeastern University, USA

Title : X-ray Advanced Characterizations of Lithium Battery Materials

Abstract :
During the lithium-ion battery charging process, Li positive ions are extracted from the cathode material (delithiation) by an external voltage source and inserted (intercalated) into an anode material (lithiation). The same process occurs in reverse when discharging. Cathode materials are crucial to improved performance, in part because there are not yet materials that can maintain high power and stable cycling with a capacity comparable to that of anode materials. We have mostly explored LiMn2O4 spinel and LiFePO4 olivine ceramic materials, which are used as cathodes. The transition metal oxidation number can be monitored with the L-edge x-ray absorption spectroscopy (XAS). In general, XAS reveals the electronic structure of unoccupied energy levels of the sample while X-ray emission spectroscopy (XES) gives the complementary information about the occupied energy levels. All these spectra can be either predicted or verified by first-principles calculations. Moreover, the theory predicts that techniques based on inelastic X-ray scattering can be used to detect the elusive lithium. In particular, X-ray Compton scattering can directly image electronic orbitals associated with lithiation as demonstrated in a recent study of LiMn2O4. So far, we have shown that x-ray spectra can be successfully predicted using first-principles. Thus, we have enabled a fundamental characterization of lithium battery materials involving spectroscopy and first-principles calculations. The detailed information we have obtained regarding the evolution of electronic states will be indispensable for understanding and optimizing battery materials.

担当者 : 櫻井 吉晴
Mail : sakurai@spring8.or.jp
PHS : 3803