Mechanism of Ionic Impedance Growth for Palladium-Containing CNT Electrodes in Lithium-Oxygen Battery Electrodes and Its Contribution to Battery Failure

Abstract

The electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and on CNT (carbon nanotube) cathode with a palladium catalyst, palladium-coated CNT (PC-CNT), and palladium-filled CNT (PF-CNT) are assessed in an ether-based electrolyte solution in order to fabricate a lithium-oxygen battery with high specific energy. The electrochemical properties of the CNT cathodes were studied using electrochemical impedance spectroscopy (EIS). Palladium-filled cathodes displayed better performance as compared to the palladium-coated ones due to the shielding of the catalysts. The mechanism of the improvement was associated to the reduction of the rate of resistances growth in the batteries, especially the ionic resistances in the electrolyte and electrodes. The scanning electron microscopy (SEM) and spectroscopy were used to analyze the products of the reaction that were adsorbed on the electrode surface of the battery, which was fabricated using palladium-coated and palladium-filled CNTs as cathodes and an ether-based electrolyte.

Poly(Ionic Liquid)‐Based Composite Gel Electrolyte for Lithium Batteries

“…In both cases, two semi‐circles are observed, one at high frequency (HF) while the other one is at a medium frequency (MF), and a straight line has been observed at low frequencies (LF). In the model, R el is the resistance of the bulk electrolyte while the first semi‐circle at HF region represents as R int ||CPE int which is the interfacial resistance between the electrolyte and the electrodes and the corresponding constant phase element (CPE) is the distributed capacity of the electrode/electrolyte interfaces . The use of CPE instead of a capacitor is due to the non‐ideal behavior of the electrode mostly the inhomogeneity, roughness and porous nature of the electrode .…”

“…In the model, R el is the resistance of the bulk electrolyte while the first semi-circle at HF region represents as R int j j CPE int which is the interfacial resistance between the electrolyte and the electrodes and the corresponding constant phase element (CPE) is the distributed capacity of the electrode/electrolyte interfaces. [49,50] The use of CPE instead of a capacitor is due to the non-ideal behavior of the electrode mostly the inhomogeneity, roughness and porous nature of the electrode. [46,51] The second semi-circle at the MF is represented as R ct j j CPE dl in the model which is the charge transfer resistance between the electrolyte and the conductive agent while the CPE dl is related to the double layer capacitance.…”

Recent Advances in All-Solid-State Lithium–Oxygen Batteries: Challenges, Strategies, Future

“…The development of an ideal cathode for ASSLOBs has been impeded practically by a limited capacity and short cycle life. For the air cathode to effectively accommodate the deposition and decomposition of the discharge products, it necessitates a high porosity structure, excellent electronic conductivity, and high catalytic activity for both oxygen reduction and oxygen evolution reactions [208]. Unfortunately, the generation and dissolution of the discharge residue (Li 2 O 2 ) in two-electron processes have slow reaction rates.…”

Anomalous Discharge Behavior of Graphite Nanosheet Electrodes in Lithium-Oxygen Batteries

“…The Nyquist plot (b) can be used to discuss the more fundamental contributions to cell impedance. The cell in its pristine state shows the commonly observed semicircle in combination with a low-frequency (LF) tail [35,[39][40][41]. Equivalent circuit modelling of porous electrodes is complex and the assignment of certain geometries to fundamental processes is often uncertain.…”