Electrochemical Oscillation during Galvanostatic Charging of LiCrTiO4 in Li-Ion Batteries

Abstract

In the late 1960s, the establishment of Prigogine’s dissipative structure theory laid the foundation for the (electro)chemical oscillation phenomenon, which has been widely investigated in some electrochemical reactions, such as electro-catalysis and electro-deposition, while the electrochemical oscillation of Li-ion batteries has just been discovered in spinel Li4Ti5O12 a few years before. In this work, spinel LiCrTiO4 samples were synthesized by using a high-temperature solid-state method, characterized with SEM (Scanning electron microscope), XRD (X-ray diffraction), Raman and XPS (X-ray photoelectron spectroscopy) measurements, and electrochemically tested in Li-ion batteries to study the electrochemical oscillation. When sintering in a powder form at a temperature between 800 and 900 °C, we achieved the electrochemical oscillation of spinel LiCrTiO4 during charging, and it is suppressed in the non-stoichiometric LiCrTiO4 samples, especially for reducing the Li content or increasing the Cr content. Therefore, this work developed another two-phase material as the powder-sintered LiCrTiO4 exhibiting the electrochemical oscillation in Li-ion batteries, which would inspire us to explore more two-phase electrode materials in Li-ion batteries, Na-ion batteries, etc.

Modeling Li-Ion Battery Voltage Oscillations and the Impact of Exchange Current Density on Oscillation Properties

“…The simulated oscillations show an inverse dependence of its frequency on the (dis)­charge rate, matching experimental results. , Using simulation data, this trend is understood as a current distribution process. Operation direction influence on the oscillation properties, as seen in experimental results, ,, is also reproduced numerically. We demonstrate how the exchange current promotes this influence, an aspect still overlooked in the literature.…”

“…One important feature present in both experimental results and our findings is the asymmetry in charging and discharging oscillations (see Figure 2a). 4,19,20 In our simulations, the origin of this behavior is the exchange current density, which has important dependence on γ TS (recall eq 4). Equation 8, obtained using transition-state theory, predicts the dependence of γ TS on c̃s.…”

“…Electrochemical oscillations were recently reported during galvanostatic operation of LIBs with surface-treated LTO electrodes. ,,, These works investigated how experimental parameters interfere in the oscillation properties such as oscillation morphology, amplitude, and frequency. Li and co-workers attributed the oscillation phenomenon to a discrete nature of the phase separation process, in which the electrochemical oscillations represent a group of particles separating phases in synchrony .…”