Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires

Type
Article

Authors
McDowell, Matthew T.
Cui, Yi

KAUST Grant Number
KUS-l1-001-12

Online Publication Date
2011-07-19

Print Publication Date
2011-10

Date
2011-07-19

Abstract
Nanostructured Si is a promising anode material for the next generation of Li-ion batteries, but few studies have focused on the electrical properties of the Li-Si alloy phase, which are important for determining power capabilities and ensuring sufficient electrical conduction in the electrode structure. Here, we demonstrate an electrochemical device framework suitable for testing the electrical properties of single Si nanowires (NWs) at different lithiation states and correlating these properties with structural changes via transmission electron microscopy (TEM). We fi nd that single Si NWs usually exhibit Ohmic I - V response in the lithiated state, with conductivities two to three orders of magnitude higher than in the delithiated state. After a number of sequential lithiation/delithiation cycles, the single NWs show similar conductivity after each lithiation step but show large variations in conductivity in the delithiated state. Finally, devices with groups of NWs in physical contact were fabricated, and structural changes in the NWs were observed after lithiation to investigate how the electrical resistance of NW junctions and the NWs themselves affect the lithiation behavior. The results suggest that electrical resistance of NW junctions can limit lithiation. Overall, this study shows the importance of investigating the electronic properties of individual components of a battery electrode (single nanostructures in this case) along with studying the nature of interactions within a collection of these component structures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Citation
McDowell MT, Cui Y (2011) Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires. Adv Energy Mater 1: 894–900. Available: http://dx.doi.org/10.1002/aenm.201100258.

Acknowledgements
We thank S. Jeong for deposition of amorphous Si. We also appreciate the helpful comments on the manuscript from Z. Beiley and A. Jackson. A portion of this work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, Subcontract NO. 6951379 under the Batteries for Advanced Transportation Technologies (BATT) Program. A portion of this work was also supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract DE-AC02-76SF0051, through the SLAC National Accelerator Laboratory LDRD project. Y.C. acknowledges support from the ONR Young Investigator Award and the King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-l1-001-12). M. T. M. acknowledges the National Defense Science and Engineering Graduate Fellowship, the National Science Foundation Graduate Fellowship, and the Chevron Stanford Graduate Fellowship for funding and support.

Publisher
Wiley

Journal
Advanced Energy Materials

DOI
10.1002/aenm.201100258

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