The effect of compression on natural graphite anode performance and matrix conductivity
Anodes for lithium-ion cells were constructed from three types of natural graphite, two coated spherical and one flaky. Anode samples were compressed from 0 to 300 kg/cm2 and studied in half-cells to study the relations between anode density, SEI formation and anode cyclability. The C/25 formation of the SEI layer was found to depend on the nature of the graphite and the anode density. Compression of the uncoated graphite lead to an increased conductivity, but only slight improvements in the efficiency of the formation process. Compression of the anodes made from the amorphous-carbon-coated graphites greatly improved both the reversible capacity and first-cycle efficiency. In addition, the fraction of the irreversible charge associated with the surface of the graphite increased with compression, from both an increase in the electrolyte contact as well as compression of the amorphous layer. The cyclability of all of the anodes tended to improve with compression. This suggests that it is the improvement in the conductivity of the anode plays more of a role in the improvement in the cyclability than the formation process.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE. Assistant Secretary for Energy Efficiency and Renewable Energy. Office of the FreedomCAR and Vehicle Technologies Program (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 835354
- Report Number(s):
- LBNL-54779; R&D Project: 674501; TRN: US200501%%76
- Journal Information:
- Journal of Power Sources, Vol. 134, Issue 2; Other Information: Submitted to Journal of Power Sources, Volume 134, No.2; Journal Publication Date: 08/12/2004; PBD: 11 Mar 2004
- Country of Publication:
- United States
- Language:
- English
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