
Understanding Inhomogeneous Reactions in Li‐Ion Batteries: Operando Synchrotron X‐Ray Diffraction on Two‐Layer Electrodes
Author(s) -
Sasaki Tsuyoshi,
Villevieille Claire,
Takeuchi Yoji,
Novák Petr
Publication year - 2015
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.201500083
Subject(s) - electrode , separator (oil production) , electrolyte , materials science , diffraction , porosity , current collector , synchrotron , perpendicular , electrochemistry , current density , ion , analytical chemistry (journal) , composite material , optics , chemistry , thermodynamics , physics , geometry , mathematics , quantum mechanics , chromatography , organic chemistry
To understand inhomogeneous reactions perpendicular to the current collector in an electrode for batteries, a method combining operando synchrotron X‐ray diffraction and two‐layer electrodes with different porosities is developed. The two layers are built using two different active materials (LiNi 0.80 Co 0.15 Al 0.05 O 2 and LiMn 2 O 4 ), therefore, tracing each diffraction pattern reveals which active material is reacting during the electrochemical measurement in transmission mode. The results demonstrate that the active material close to the separator is obviously more active than that one close to the current collector in the case of low porosity electrodes. This inhomogeneity should be due to the rate‐limitation and especially to low average ionic conductivity of the electrolyte in the porous electrode because the current flows first mainly into the electrode regions close to the separator. The inhomogeneity is found to be mitigated by the adjustment of the electrode density and thus porosity. Hence, the novel operando method reveals a clear inhomogeneous reaction perpendicular to the current collector.