Extraction of Layerwise Conductivities in Carbon-Enhanced, Multilayered LiFePO[sub 4] Cathodes
- 1 January 2005
- journal article
- research article
- Published by The Electrochemical Society in Journal of the Electrochemical Society
- Vol. 152 (5), A1001-A1010
- https://doi.org/10.1149/1.1890766
Abstract
We performed experimental studies to determine electronic properties of multilayered LiFePO4LiFePO4 cathodes in order to quantify reductions in LiFePO4LiFePO4 matrix resistivity and/or contact resistances between matrices and current collectors by addition of carbon black and graphite. In order to extract these layerwise and interlayer properties, we extended the Schumann-Gardner approach to analysis of a four-point probe experiment and solved the resulting coupled nonlinear equations numerically. We studied five cathodes with varying amounts (3-12wt%)(3-12wt%) and types (carbon black, graphite) of conductive additives. LiFePO4LiFePO4 particles within the electrodes were precoated with carbon before mixing with additives and binder. Experimental results showed reductions of ∼62%∼62% in electrical resistivities of LiFePO4LiFePO4 matrix with addition of carbon black from 3to10wt%3to10wt% ; addition of graphite additives produced only small reductions. For concentrations above 6wt%6wt% of conductive additives, homogeneous electronic resistivities were observed. Contact resistances at interfaces between LiFePO4LiFePO4 matrix and carbon coating of current collector and between carbon coating and current collector were similar in all cases, indicating consistency in manufacturing. Future work will focus on combining models for capacitive loss with models for conductive properties, along with experimental verifications.Keywords
This publication has 26 references indexed in Scilit:
- Conductivity improvements to spray-produced LiFePO4 by addition of a carbon sourceMaterials Letters, 2004
- Particle Compression and Conductivity in Li-Ion Anodes with Graphite AdditivesJournal of the Electrochemical Society, 2004
- Influence of carbon black distribution on performance of oxide cathodes for Li ion batteriesElectrochimica Acta, 2003
- The role of carbon black distribution in cathodes for Li ion batteriesJournal of Power Sources, 2003
- Necessary and sufficient conditions for optimal flow control in multirate multicast networksIEE Proceedings - Communications, 2003
- Errors in Resistivities Calculated by Multilayer Analysis of Spreading ResistancesJournal of the Electrochemical Society, 1979
- Spreading resistance calculations for graded structures based on the uniform flux source boundary conditionSolid-State Electronics, 1977
- On the calculation of spreading resistance correction factorsSolid-State Electronics, 1976
- Spreading resistance correction factorsSolid-State Electronics, 1969
- Complicated MathematicsPhysical Review Letters, 1963