TY - JOUR
T1 - Pressure-Dependent Electrochemical Behavior of Di-Lithium Rhodizonate Cathodes
AU - Madsen, Kenneth E.
AU - Shin, Minjeong
AU - Gewirth, Andrew A.
N1 - Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/7/27
Y1 - 2021/7/27
N2 - Herein, we investigate the electrochemical properties of the high-capacity organic cathode material di-lithium rhodizonate (Li2C6O6) under different applied mechanical loads. We demonstrate, through a combination of pressure-dependent voltammetry and electrochemical impedance spectroscopy, that the charge-transfer kinetics at the cathode/electrolyte interface is strongly impacted by the magnitude of the load applied to the cathode. At low pressures, lithium rhodizonate displays untenably high charge-transfer impedances toward lithiation and delithiation. As the load applied to the cathode material is increased, the charge-transfer impedance decreases, reflecting a reduction in the overpotential associated with lithiation and delithiation. Furthermore, pressure-dependent galvanostatic cycling reveals that cells cycled at high pressures exhibit improvements in their overall capacity retention when compared with their low-pressure counterparts. Using a combination of postmortem X-ray diffraction and first-principles calculations, we show that, in the absence of sufficient external load, lithium rhodizonate converts from its redox-active structure to a redox-inactive structure, resulting in the observed rapid capacity fade. As the pressure applied to the electrode is increased, this phase transition is suppressed, resulting in improvements in both long-term stability and electrochemical kinetics.
AB - Herein, we investigate the electrochemical properties of the high-capacity organic cathode material di-lithium rhodizonate (Li2C6O6) under different applied mechanical loads. We demonstrate, through a combination of pressure-dependent voltammetry and electrochemical impedance spectroscopy, that the charge-transfer kinetics at the cathode/electrolyte interface is strongly impacted by the magnitude of the load applied to the cathode. At low pressures, lithium rhodizonate displays untenably high charge-transfer impedances toward lithiation and delithiation. As the load applied to the cathode material is increased, the charge-transfer impedance decreases, reflecting a reduction in the overpotential associated with lithiation and delithiation. Furthermore, pressure-dependent galvanostatic cycling reveals that cells cycled at high pressures exhibit improvements in their overall capacity retention when compared with their low-pressure counterparts. Using a combination of postmortem X-ray diffraction and first-principles calculations, we show that, in the absence of sufficient external load, lithium rhodizonate converts from its redox-active structure to a redox-inactive structure, resulting in the observed rapid capacity fade. As the pressure applied to the electrode is increased, this phase transition is suppressed, resulting in improvements in both long-term stability and electrochemical kinetics.
UR - http://www.scopus.com/inward/record.url?scp=85111216065&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85111216065&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.1c01523
DO - 10.1021/acs.chemmater.1c01523
M3 - Article
AN - SCOPUS:85111216065
SN - 0897-4756
VL - 33
SP - 5738
EP - 5747
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 14
ER -