Critical evaluation of activated carbon as a counter electrode in post-lithium batteries

The development of post-lithium batteries based on cations such as K⁺, Mg²⁺, and Ca²⁺ requires reliable electrochemical evaluation methods. Owing to the frequent instability of metallic counter electrodes, activated carbon is increasingly used as an alternative, although its improper use can significantly bias the interpretation of electrochemical data.

Alexandru Vlad (WEL Research Institute – UCLouvain) and co-workers systematically investigated the influence of several key parameters on the behaviour of activated carbon in systems including a Ca–Zn–PTtSA positive electrode. The researchers demonstrated that poorly controlled conditions can lead to artificial voltage shifts, errors in the estimation of diffusion coefficients, and the misinterpretation of electrolyte decomposition as intrinsic redox activity. Based on these findings, they propose practical recommendations for the proper use and reporting of activated carbon counter electrodes.

Reference : Markowski et al, How improper use of activated carbon leads to biased data interpretation in post-li battery systems, J Mater Chem A (2026) https://doi.org/10.1039/D6TA02368A