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Effects of Graphite Structure and Ion Transport on the Electrochemical Properties of Rechargeable Aluminum–Graphite Batteries
Version 2 2019-11-04, 19:03
Version 1 2019-10-31, 23:03
journal contribution
posted on 2019-11-04, 19:03 authored by Jeffrey H. Xu, Damon E. Turney, Ankur L. Jadhav, Robert J. MessingerRechargeable aluminum–graphite
batteries using chloroaluminate-containing ionic liquid electrolytes
store charge when molecular chloroaluminate anions intercalate into
graphite. However, the relationship between graphite structure and
bulk electrochemical properties is not well understood. Here,
we characterize the structure of natural, synthetic, and pyrolytic
graphites and analyze their electrochemical performance in aluminum–graphite
cells, revealing insights into their charge storage mechanisms,
rate capabilities, Coulombic efficiencies, and extended cycling stabilities.
Natural graphite exhibited the highest specific capacity at all potentials
and the greatest capacity retention during variable-rate galvanostatic
cycling. The compositions of the intercalated electrodes (Cx[AlCl4]) were determined coulometrically,
and their stage numbers were rationalized by using a hard-sphere model.
Variable-rate CV analyses establish that the rates of reversible electrochemical
chloroaluminate intercalation in natural and synthetic graphites are
effectively reaction-limited at potentials <2.1 V, and neither
strongly diffusion- nor reaction-limited above 2.3 V, differing significantly
from the diffusion-limited electrochemical intercalation of lithium
cations into graphite. The results yield a new understanding of the
relationships between graphite structure, ion transport, and electrochemical
properties in rechargeable aluminum–graphite batteries and
are expected to aid the rational design of graphite electrodes with
enhanced electrochemical performance.
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graphite electrodes withgraphite structurecharge storage mechanismselectrochemical performancediffusion-limited electrochemical intercalationVariable-rate CV analyseselectrochemical chloroaluminate intercalationbulk electrochemical propertieselectrolytes store chargechloroaluminate anions intercalate
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