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Three‐Phase Multiscale Modeling of a LiCoO 2 Cathode: Combining the Advantages of FIB–SEM Imaging and X‐Ray Tomography
Author(s) -
Zielke Lukas,
Hutzenlaub Tobias,
Wheeler Dean R.,
Chao ChienWei,
Manke Ingo,
Hilger André,
Paust Nils,
Zengerle Roland,
Thiele Simon
Publication year - 2015
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201401612
Subject(s) - materials science , nanopore , electron tomography , ion , nanoscopic scale , focused ion beam , tomography , nanotechnology , glassy carbon , tomographic reconstruction , phase (matter) , lithium (medication) , scanning electron microscope , electrode , transmission electron microscopy , scanning transmission electron microscopy , electrochemistry , composite material , optics , cyclic voltammetry , chemistry , medicine , physics , quantum mechanics , organic chemistry , endocrinology
LiCoO 2 electrodes contain three phases, or domains, each having specific‐intended functions: ion‐conducting pore space, lithium‐ion‐reacting active material, and electron conducting carbon‐binder domain (CBD). Transport processes take place in all domains on different characteristic length scales: from the micrometer scale in the active material grains through to the nanopores in the carbon‐binder phase. Consequently, more than one imaging approach must be utilized to obtain a hierarchical geometric representation of the electrode. An approach incorporating information from the micro‐ and nanoscale to calculate 3D transport‐relevant properties in a large‐reconstructed active domain is presented. Advantages of focused ion beam/scanning electron microscopy imaging and X‐ray tomography combined by a spatial stochastic model, validated with an artificially produced reference structure are used. This novel approach leads to significantly different transport relevant properties compared with previous tomographic approaches: nanoporosity of the CBD leads to up to 42% additional contact area between active material and pore space and increases ionic conduction by a factor of up to 3.6. The results show that nanoporosity within the CBD cannot be neglected.