Huagen Peng, Ph.D.

Solid polymer electrolyte (SPE) rechargeable lithium batteries offer several potential advantages over current battery technologies based on liquid electrolytes. Easy containment of the solid electrolyte allows for more latitude in designing the battery shape, higher energy densities, and reduced environmental hazards. However, these potential advantages have not been fully realized after decades of research due to the low ion conductivity of SPE. Dramatic increases of the Li ion conductivity are needed and this progress requires the understanding of Li conduction mechanism.

PEO is widely studied as the polymer matrix for SPE. The lithium mobility is believed to be coupled with PEO segmental motion as one lithium ion is coordinated by several ether oxygen atoms. Quasielastic neutron scattering (QENS) is a well-suited technique to study the PEO segmental motion. Paring QENS with conductivity measurement by impedance spectroscopy on PEO/lithium salt complex can quantify the coupling of PEO segmental motion and lithium diffusion. The approach can be extended to SPE systems with additives such as nanoparticles and plasticizers, and therefore, the mechanism behind lithium conductivity improvement can be revealed.

Select Non-NIST publications:

• Peng HG, Kong YP, Yee AF, "Relaxation Kinetics of Nanostructures on Polymer Surface: Effect of Stress, Chain Mobility and Spatial Confinement", Macromolecules, Submitted, 2009

• Peng HG, Chi DZ, Wang WD, Li JH, Zeng KY, Vallery RS, Frieze WE, Skalsey MA, Gidley DW, and Yee AF, "Pore sealing by NH3 plasma treatment of porous low dielectric constant films", J. Electrochem. Soc. 154, G85-G94 (2007)

• Gidley DW, Peng HG, and Vallery RS, "Positron Annihilation as a Method to Characterize Porous Materials", Annu. Rev. Mater. Res. 36, 49-79 (2006)

• Peng HG, Vallery RS, Frieze WE, Liu M, Gidley DW, Yim JH, Jeong HD, and Kim J, "Deducing Pore Structure and Growth in Nanoporous Thin Films", Appl. Phys. Lett. 87, 161903 (2005)

• Peng HG, Frieze WE, Vallery RS, Gidley DW, Moore DL, and Carter RJ, "Revealing Hidden Pore Structure in Nanoporous Thin Films Using Positronium Annihilation Lifetime Spectroscopy", Appl. Phys. Lett. 86, 121904 (2005)

Professional Affiliations:

• American Physical Society (APS)

• Materials Research Society (MRS)