Off-line method to determine the electrode balancing of Li-ion batteries

Abstract

In this paper, we propose a non-invasive method to determine the electrode balancing of the lithium-ion batteries, which is the determination of (i) individual electrodes capacities and (ii) individual curves of equilibrium potentials of the electrodes as functions of the battery state of charge. The proposed method requires the average measurements of the battery voltage between discharge and charge for a low current. This averaged voltage is then associated with the reference average curves of the electrode equilibrium potentials issued from literature. To determine the electrode balancing, the method was first used on a pristine LiFePO 4 /graphite cell. The results are consitent with this cell data and the proposed method accuracy is compared to a reference method of the litterature. We then used the proposed method on an aged cell of the same type to evaluate the method robustness with respect to the change in the cell state of health. The tracking of each electrode capacity during the battery lifespan can be used as a non-invasive diagnosis tool to monitor the state of health evolution to each electrode. Furthermore, the access to the individual curves of electrodes equilibrium potentials as functions of the battery state of charge is the first step towards the implementation of a non-invasive tool for an optimal prediction of the battery operating limits during fast recharging.

In Situ Electrochemical Regeneration of Degraded LiFePO4 Electrode with Functionalized Prelithiation Separator

“…Figure S8, Supporting Information provides the relevant information of the graphite half cell, which exhibits a typical charge/discharge curve with three plateaus for the first cycle and a charging capacity of 362.1 mAh g −1 . [ 44 ] The initial charge/discharge profile as well as the internal structure of the regenerated cell is shown in Figure 5c. The initial charging specific capacity of the regenerated cell (calculated on the mass of LFP) reaches 241.6 mAh g −1 at 0.05 C (1 C = 170 mAh g −1 ) with an apparent voltage plateau attributable to the decomposition of Li 2 C 2 O 4 at around 4.4 V. Because of the Li + loss in cathode caused by electrochemically stripping 20% of theoretical lithium content in pristine LFP, the charging capacity of D‐LFP is only 146.2 mAh g −1 .…”

Differential Analysis of Galvanostatic Cycle Data from Li-Ion Batteries: Interpretative Insights and Graphical Heuristics

“…To retain focus on the qualitative graphical methods advocated in this work, we have not attempted this exercise on the small quantity of data presented here. For further detail, we direct the reader to published reports on fitting and numerical regression methods introduced for this purpose; ,,,,− context is given by a recent review, and we note a significantly increased number of subsequent publications on this topic during 2021–2022.…”

Equivalent Circuit Model For Sodium-Ion Batteries With Physical-Based Representations Of Their Non-Linearities

“…For this, we used the SoC concept. Mergo Mbeya et al [14] proposed a relation between the SoC and the mean concentration c mean in the electrodes of LiFePO 4 /graphite cells. We propose to decompose c surf into the sum of a mean concentration c mean and a shift from the mean concentration ∆c .…”