Analysis of the counter-electrode potential in a 3-electrode lithium ion battery cell

• The potential course of a Li metal CE is observed in a 3-electrode battery cell.
• The CE potential was found to be connected to phase transitions in the WE.
• The analysis of the CE yields information about the current distribution in the WE.
• This relation can be used to study the current distribution in porous electrodes.

A phenomenon which was not yet described is observed in the potential course of a lithium metal counter electrode (CE) employed for investigations of porous graphite electrodes (WE). The potential characteristics of the CE were found to be strictly connected to the lithium concentration in the active material of the WE. The authors suggest that the observed phenomena at the CE are related to changes of the current density distribution across the thickness of the porous WE. The local depletion/enrichment of lithium in the pores affects the lithium concentration gradient in the electrolyte which results in changes of the overpotential at the CE. This relation may be used prospectively to study the current density distribution in porous electrodes as a function of time, C — rate and state of charge.

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