Electrochemical Behavior and Relaxation-Induced Potential Recovery in Polypeptide-Based Cathodes for Primary Lithium Batteries

In this paper, polypeptides were investigated as groundbreaking advancements to effective cathode-active materials for prototypes of high-capacity primary lithium batteries. The influence of mechanical pressing, discharge current, and relaxation behavior on the electrochemical performance of peptide-based electrodes was analyzed. Cathodes prepared under optimized pressure exhibited improved interparticle contact, which resulted to the achievement of high discharge process performance: increase of specific energy to 5,600 mWh g −1 and stable specific capacity 2,900 mAh g −1 under current density 10 mA g −1 . Galvanostatic testing revealed a gradual decrease of specific capacity with increasing current to 70 mA g −1 , indicating kinetic limitations typical for organic electrodes. Furthermore, galvanostatic intermittent discharge experiments demonstrated a pronounced potential recovery during relaxation periods, which allows to significantly increase the total discharge capacity. This relaxation-induced recovery of potential was interpreted as a suggesting a reversible redistribution of lithium ions within the porous biopolymer matrix and partial effect of slow electrolyte redistribution. Specific capacity increased by 6,000 mAh g −1 for galvanostatic intermittent discharge mode compared to 2,900 mAh g −1 in galvanostatic continuous mode. The study highlights the role of mechanical densification and molecular mobility in modulating charge transport within peptide-based cathodes, providing a foundation for further optimization of high-capacity organic lithium batteries systems.