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conferenceseries
.com
Volume 7
Biosensors Journal
ISSN: 2090-4967
Electrochemistry 2018
June 11-12, 2018
June 11-12, 2018 | Rome, Italy
4
th
International Conference on
Electrochemistry
Sodium vs. lithium co-intercalation with diglyme electrolyte into graphite anodes: Evidence from
multi-nuclear solid state NMR spectroscopy
Nicole Leifer, Miryam Fayena Greenstein, Albert Mor, Gil Goobes
and
Doron Aurbach
Bar Ilan University, Israel
T
he growing need for cost-effective batteries for large scale energy storage is motivating sodium-ion battery (SIB)
technology development, especially in applications where energy density/weight is not crucial. However, the performance
of intercalation compounds as viable electrodes for SIB has not matched the success of Li-ion batteries (LIBs). Graphite, as
the most widely used anode material in current commercial LIBs, exhibits very low capacities (<35 mAh/g) as an anode
material in SIBs, as compared to 372 mAh/g for Li. This has been attributed to the instability of the Na ions intercalated
into graphite, unlike Li ions. By using diglyme as the electrolyte solvent, however, reversible Na intercalation in graphite was
achieved with capacities reaching 80 mAh/g for up to 1000 cycles and >99% reversible capacity. The good recyclability and
limited capacity fade was attributed to the concomitant intercalation of the alkali ions with coordinated diglyme molecules
(co-intercalation), i.e. the formation of ternary (t)-GIC complexes upon discharge. Analogous studies with Li gave inferior
results, with exfoliation of the graphite layers upon extended cycling. Computational studies suggest that the Na-diglyme
complex intercalates and binds quite differently than Li-diglyme complex in the graphite. However, experimental evidences
of co-intercalation are only indirect and so is their relation to the disparate electrochemical behavior of Na vs. Li. This study
examined the graphite anode material, diglyme molecules and the alkali ions upon electrochemical cycling against Na or Li
metal in a diglyme-based electrolyte solution via solid-state NMR spectroscopy. Direct evidence for co-intercalation, as well
as qualitative and quantitative comparisons of the details of the ion-solvent-graphite interactions, are provided via
23
Na,
7
Li,
1
H and
13
C NMR measurements. The conclusion from this work should prove useful for improving the performance of other
higher capacity carbon based anodes for SIBs.
nickyl@alum.mit.eduBiosens J 2018, Volume 7
DOI: 10.4172/2090-4967-C1-003