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Influence of Electronic Type Purity on the Lithiation of Single-Walled Carbon Nanotubes.

Abstract: 

Single-walled carbon nanotubes (SWCNTs) have emerged as one of the leading additives for high-capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current
collection efficiency, and charge/discharge rate for high power applications.
However, since as-grown SWCNTs possess a distribution of physical and electronic structures, it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Toward this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content.
Experimentally, vacuum-filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity
than their semiconducting counterparts, which is consistent with ab initio molecular dynamics and density functional theory calculations in the limit
of isolated SWCNTs. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels
comparable to metallic SWCNTs, which is corroborated by theoretical calculations that show increased lithiation of semiconducting SWCNTs in the
limit of small SWCNT*SWCNT spacing. Overall, these results will inform ongoing efforts to utilize SWCNTs as conductive additives in nanocomposite
lithium ion battery electrodes.

Citation: 
Jaber-Ansari L, H Iddir, LA Curtiss, and MC Hersam.2014."Influence of Electronic Type Purity on the Lithiation of Single-Walled Carbon Nanotubes."ACS Nano 8(3):2399-2409. doi:10.1021/nn405921t
Authors: 
L Jaber-Ansari
H Iddir
LA Curtiss
MC Hersam