research

 

NSF-DMR

Title

"NanoDomain Structure and Multifunctional Properties of Polymer Derived Ceramics (PDCs)", supported by the Ceramics Program, under Dr. Lynnette Madsen

 

The Objective

To gain fundamental insights into how the nanodomain network of graphene (Saha, Williamson and Raj, 2008; DOI:, and mixed-bond tetrahedra of Si-C-N-O evolve from the organic state, and how they influence functional properties of the PDCs.

The Approach

The electrochemical insertion of Li into the PDCs has given fascinating results raising fundamental questions about the molecular sites, and their energy levels where Li resides. The polymer-route to processing enables easy fabrication of thin films anodes. In particular we are interested in the molecular mechanisms for the origin of first cycle loss and hysteresis exhibited by the PDCs.

Key Findings

PDCs have more than three times the capacity for Li than graphite. The Sanchez-Jiminez publication given below shows that the Li is stored in the mixed bond, SiCO tetrahedra in the nanodomain structure of the PDCs.

Recent Publications on Li Intrercalation in PDCs:

Ahn, D. & Raj, R. 2011, "Cyclic stability and C-rate performance of amorphous silicon and carbon based anodes for electrochemical storage of lithium", Journal of Power Sources, vol. 196, no. 4, pp. 2179-2186.
DOI: 10.1111/j.1551-2916.2006.00920.x

Ahn, D. & Raj, R. 2010, "Thermodynamic measurements pertaining to the hysteretic intercalation of lithium in polymer-derived silicon oxycarbide", Journal of Power Sources, vol. 195, no. 12, pp. 3900-3906.
DOI: 10.1016/j.jpowsour.2009.12.11

Sanchez-Jimenez, P.E. & Raj, R. 2010, "Lithium Insertion in Polymer-Derived Silicon Oxycarbide Ceramics", Journal of the American Ceramic Society, vol. 93, no. 4, pp. 1127-1135.
DOI: 10.1111/j.1551-2916.2009.03539.x

Shen, J., Ahn, D. & Raj, R. 2011, "C-rate performance of silicon oxycarbide anodes for Li plus batteries enhanced by carbon nanotubes", Journal of Power Sources, vol. 196, no. 5, pp. 2875-2878.
DOI: 10.1016/j.jpowsour.2011.02.091

Shen, J. & Raj, R. 2011, "Silicon-oxycarbide based thin film anodes for lithium ion batteries", Journal of Power Sources, vol. 196, no. 14, pp. 5945-5950.
DOI: 10.1016/j.jpowsour.2011.02.091

 

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