A Graphical Approach for Identifying the Limiting Processes in Lithium-Ion Battery Cathode Using Electrochemical Impedance Spectroscopy

Abstract

Electrochemical impedance spectroscopy (EIS) has been proposed as an in situ strategy for the analysis of materials properties applied in the study of lithium-ion batteries (LIBs). However, the number and physical nature of the processes occurring simultaneously, combined with the typical interpretation of EIS spectra make the study challenging. To make the EIS interpretation more inclusive, in this work a graphical Bode diagram deconvolution is proposed, utilizing time constants τ (R-CPE), associated with relaxation of the phenomena occurring in battery composite electrodes. Since the effect of the additives on the electrode composite is still controversial and difficult to analyze for other in situ techniques, the graphical strategy is first applied to a LiFePO 4 cathode with PVDF as the binder, to discriminate the contribution of each τ during different state of charge (SOC). This is done by removing the influence of counter electrode using a commercial three-electrode set-up cell. Then, the same cathode was evaluated, but with a Single Lithium-Ion Conducting Binder (SLICB). The electrode modification was easily observed with the graphical analysis. The results show that SLICB improved the speed of the processes, moving them to high frequencies, given that the polymer provides a continuous supply of ions diminishing concentration polarization.

Organic–Inorganic Hybrid Cathode with Dual Energy‐Storage Mechanism for Ultrahigh‐Rate and Ultralong‐Life Aqueous Zinc‐Ion Batteries

“…Besides, Bode‐phase angles diagrams (Figure S11b,c, Supporting Information) indicate a prevalence of capacitive‐like behavior at high voltages potentials (>0.8 V). [ 50 ] As discussed above, the high‐performance EDA‐VO cathode with ultrahigh‐rate and ultralong‐life in ZIBs may be ascribed to the superior electrode kinetics and high capacitive contributions. The remarkable specific capacity and higher operating voltage result in a high energy density (310.8 W h kg −1 ) of the EDA‐VO cathode, which is overwhelmingly superior to other reported organic and vanadate cathodes for ZIBs (Figure 3e).…”

A Toolbox of Reference Electrodes for Lithium Batteries

“…The individual dynamic electrode behavior can be distinguished from an adjusted three‐electrode EIS measurement with minimal CE influence, [ 63 ] which greatly improves our understanding of the electrode processes. Figure 9d shows the respective contributions of the film resistance and charge transfer resistance from the anode and cathode in an MCMB|LiCoO 2 cell at different states of charge (SOCs).…”

Interface Engineering on Cellulose‐Based Flexible Electrode Enables High Mass Loading Wearable Supercapacitor with Ultrahigh Capacitance and Energy Density

“…The fitting results show consistent conclusion, which further proves a rapid ion/electron transport in CNT-i-Cell electrode despite the high mass loading (Figure S14, Supporting Information). [29,30] Kinetics analysis was further performed to evaluate the electrochemical behavior. The CV curves of CNT-i-Cell electrode are nearly rectangular (Figure S16a, Supporting Information), reflecting the rapid electron and ion transport in the electrode.…”

“…The fitting results show consistent conclusion, which further proves a rapid ion/electron transport in CNT‐i‐Cell electrode despite the high mass loading (Figure S14, Supporting Information). [ 29,30 ]…”