Superior flexibility of a wrinkled carbon shell under electrochemical cycling
KAUST DepartmentAdvanced Nanofabrication, Imaging and Characterization Core Lab
Physical Sciences and Engineering (PSE) Division
Materials Science and Engineering Program
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AbstractNanocarbon composites have been extensively employed in engineering alloy-type anodes in order to improve the poor cyclability caused by the enormous volume changes during lithium (Li+) insertion/extraction. The chemical vapor deposited wrinkled carbon shell (WCS) shows high electrical conductivity, excellent thermal stability and remarkable mechanical robustness, which help in retaining the structural integrity around the tin (Sn) anode core despite ∼250% variation in volume during repetitive lithiation and delithiation. In situ transmission electron microscopy reveals no embrittlement in the lithiated WCS, which fully recovers its original shape after severe mechanical deformation with no obvious structural change. Further analysis indicates that the capacity to accommodate large strains is closely related to the construction of the carbon shell, that is, the stacking of wrinkled few-layer graphenes. Both the pre-existing wrinkles and the few-layer thickness render the carbon shell superior flexibility and good elasticity under bending or expansion of the interior volume. Moreover, the WCS possesses fast lithium ion diffusion channels, which have lower activation barriers (∼0.1 eV) than that on a smooth graphene (∼0.3 eV). The results provide an insight into the improvement in cycle performance that can be achieved through carbon coating of anodes of lithium ion batteries. © 2014 The Royal Society of Chemistry.
SponsorsH. Wang acknowledges the financial support from the National Science Foundation of China (Grant no. 11322219), National Program for Special Support of Top-Notch Young Professionals and Fundamental Research Funds for the Central Universities. Q. Li acknowledges the award for excellent doctoral student from the Ministry of Education (Grant no. 188310-720907/014).
PublisherRoyal Society of Chemistry (RSC)
JournalJournal of Materials Chemistry A