Lithium Secondary Battery Based on Intercalation in Carbon Fibers As Negative Electrode

Endo, Morinobu; Nakamura, Junichi; Emori, Akihiko; Sasabe, Yutaka; Takeuchi, Kenji; Inagaki, Michio

doi:10.1080/10587259408051684

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…Natural graphite may, in fact, be inherently unsuitable for some fast charge/discharge applications. On the other hand, MCMBs and graphitized carbon fibers show lower capacity, [3][4][5][8][9][10][11][12][13][14][15] but because of their low resistivities and special geometries, effective resistivity and contact resistance may possibly be minimized for the electrode. Ultimately, the trade-offs among factors in electrochemical performance can be resolved with improved simulations of materials performance.…”

Section: Discussionmentioning

confidence: 99%

“…Electrode resistivity is a function of resistivity of active materials, contact resistance, and resistivity of current collector. Improved anode performance via addition of conductive carbons in Li-ion secondary batteries has been demonstrated in various Li-ion electrochemistries [3][4][5][6][7][8][9][10][11][12][13][14][15] through interruption of solvent cointercalation into basal planes. Solvent cointercalation is governed by the texture of the GICs, which varies with material type ͑natural graphite, mesocarbon microbeads, carbon fibers, etc.͒ Several workers 3,4,7 have attempted to reduce electrolyte decomposition on graphite via combination of material types on the anode, e.g., mixing of flaky and spherical graphite.…”

Section: Conductionmentioning

confidence: 99%

“…7 Addition of conductive carbons in Li-ion secondary batteries has also been explored. [8][9][10][11][12][13] Larger, metallic fibers ͑with lengths and diameters on the order of micrometers͒ were shown by Ahn 8 to improve anodic conductivity, capacity, and high rate capability. Takami et al 9 and Osaki et al 10 showed that the MPCFs used as anodic materials for lithium-ion cells offered higher capacity rates and greater reversibility than those of graphitic anode materials.…”

Section: Conductionmentioning

confidence: 99%

“…More recently, chopped vapor grown carbon fibers ͑VGCFs͒ have been studied in detail as a conductive additives to Li-ion anodes. Endo et al 12 linked the structural features of these fibers to improved cell performance. Others, including Tatsumi et al 13 have compared various manufacturing techniques for the materials, showing, for example, that VGCFs produced by chopping after graphitization provide higher capacity than those produced by chopping before graphitization.…”

Section: Conductionmentioning

confidence: 99%

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Conduction in Multiphase Particulate/Fibrous Networks

Wang¹,

Cook

Sastry

2003

J. Electrochem. Soc.

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Several promising Li-ion battery technologies incorporate nanoarchitectured carbon networks, typically in the form of whisker/ particle blends bonded with thermoplastic binders to form the anodes. Degradation of these materials is currently a persistent problem, with damage presenting as blistering and/or delamination of the electrode. Both material composition and morphology play a role in these critical failure modes, and are explored in the present work as they affect conduction in practical battery materials. Lawrence Berkeley National Laboratories and the Institut de Recherche d'Hydro-Quebec supplied the materials studied in this work. Our present approach builds on our previous numerical work, incorporating real material morphology and careful selection of boundary conditions to reduce the numerical difficulties posed by singularities in the field solution, due to phase contrast, sharp corners, etc. In order to allow use of these models for various shapes of particles, we provide a few simple geometrical relations for calculation of total surface area for various morphologies of electrode materials. A four-point-probe technique was employed to obtain the experimental conductivities. Although the existence of contact resistance is well known, there is little literature regarding a technique to measure its value; here, we also present a method for quantifying it, assuming that the anode layer is comprised of two layers. Voltage functions for each layer are determined by enforcement of voltage continuity at the interfaces, current intensities at the inlet and outlet on both sides of interface, and assumption of zero voltage in the second layer as z → ϱ. The four-point-probe technique is suitable for the electrode materials tested, offering reasonable experimental precision in a simple setup. The results of this study offer some insight into the design of active materials. The model shows applicability to a wide variety of materials, including those comprised of fibers, particles, and flakes. Comparisons among simulation predictions and real material conductivities showed very good agreement. An obvious subject of future work is combined electrochemical, conduction, and mechanical modeling of these materials.

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