Voltage hysteresis during lithiation/delithiation of graphite associated with meta-stable carbon stackings
Publication date
2020-11-27
Document type
Research article
Author
Organisational unit
ISSN
Series or journal
Journal of materials chemistry A
Periodical volume
9
Periodical issue
1
First page
492
Last page
504
Peer-reviewed
✅
Part of the university bibliography
✅
Abstract
Cell voltage is a fundamental quantity used to monitor and control Li-ion batteries. The open cir- cuit voltage (OCV) is of particular interest as it is believed to be a thermodynamic quantity, free of kinetic effects and history and, therefore, “simple” to interpret. Here we show that the OCV characteristics of graphite show hysteresis between charge and discharge that do not solely orig- inate from Li dynamics and that the OCV is in fact history dependent. Combining First-Principles calculations with temperature-controlled electrochemical measurements, we identify a residual hysteresis that persists even at elevated temperatures of greater than 50 degC due to differences in the phase succession between charge and discharge. Experimental entropy profiling, as well as energies and volume changes determined from First-Principles calculations, suggest that the residual hysteresis is associated with different host lattice stackings of carbon and is related to Li disorder across planes in stage II configurations.
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