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Abstract A three-electrolyte cell configuration, in which an additional compartment filled with salt solution is created between the cation-exchange membrane and the anion-exchange membrane to separate the respective opposite charged ionic species, can be used to realize novel electrochemical systems using promising redox couples. Using lead-acid metal hydride hybrid redox couple as a typical three-electrolyte prototype, we monitored the potential change of individual components during operation to obtain better understanding on the factors affecting the electrochemical performance (including types of salt solution, electrolyte concentration, inter-electrode gap). Key issues (i.e., salting-out) and proposed solutions are discussed. This work offers new solutions to develop promising energy storage techniques. Highlights • Effect of salt solution, concentration and inter-electrode gap of the three-electrolyte battery system was studied. • Salt solution with higher ionic conductivity in the buffer chamber, lowers the change voltage across the membranes. • The inter-electrode gap is optimised to reduce the internal resistance of the system. [ABSTRACT FROM AUTHOR]

An iron-nitrogen-doped core-shell mesoporous carbon support loaded with a RuO2 catalyst was used as a Li-O2 cathode. Corrosion and degradation problems were avoided by doping carbon with iron and nitrogen. Well-dispersed RuO2 in the hierarchical porous structure facilitated a reversible nanoscale solid-phase reaction. At 2.0 A g−1 (on the basis of catalyst plus carbon support), a capacity of 10 Ah g−1 was demonstrated with a discharge potential of 2.4 V and a corresponding recharge potential of 3.6 V. On the other hand, at 1.0 A g−1, the discharge and recharge potentials are maintained at 2.5 V and 3.5 V, respectively, over 50 cycles. [ABSTRACT FROM AUTHOR]

Abstract: A series of experiments have been performed to investigate the effects of three electrolytes of different compositions (EO, EA and EM) on the electrochemical characteristics of MmNi3.55Co0.72Al0.3Mn0.43 hydrogen storage alloy electrode. Electrolytes EA and EM were obtained by adding appropriate amounts of Al2(SO4)3 and MnSO4 to the original electrolyte EO (6M KOH+1wt% LiOH), respectively. Electrode activation, maximum capacity, cycle life, self-discharge and high-rate discharge characteristics have been studied. It was found that a maximum capacity of about 260mAh/g has been obtained for the alloy electrodes in all these electrolytes after 5–7 cycles of charging/discharging. The alloy electrodes have a good durability in electrolytes EA and EM, especially after 175 cycles. Using the capacity retention as an indication of self-discharge resistance, almost identical degree of capacity retention (82% after 4 days and 45% after 16 days) has been observed at 298K, regardless of the electrolytes used. When tested at higher temperature, however, a higher capacity retention (46% after 3 days) at 333K has been observed for electrodes in electrolyte EA, and about 32% for electrodes in both electrolytes EO and EM. As to high-rate discharge behavior of the results of high-rate discharge tests indicated that about 50% of discharge efficiencies were obtained in the three electrolytes at 333K by continuous-model high-rate discharge method, at a discharge rate of 7C, and 22% in 298K. The alloy electrode in electrolyte EM has the best durability, in which about 50% of discharge efficiency at DC=9C was obtained by step-model high-rate discharge method at 333K, which was even higher than that at 298K. [Copyright &y& Elsevier]

Three-electrolyte configuration with two oppositely charged ion-exchange membranes can be used to yield various promising pH differential power sources. pH change, ion transport and potential profiles across the membranes and electrode/electrolyte interfaces of a three-electrolyte pH differential lead dioxide-metal hydride system are therefore systematically investigated for the first time. We find that i) pH changes of the acid and alkaline chambers are dependent on the combined effect of the electrode reaction and the ion transport. In addition, the pH change of the middle chamber is also affected by the crossover of protons from acid chamber if the anion-exchange membrane has a low permselectivity; ii) the electrical potential gradient mainly controls the ion transport with current flows; iii) the high overall cell voltage is attributed to the large pH acid-alkaline , while the potential across the membranes and electrode/electrolyte interfaces is affected by both pH and the concentration gradient. Key issues and proposed solutions are discussed to improve the electrochemical performance of this three-electrolyte pH differential electrochemical system. This work offers new opportunities to develop promising energy storage technologies. Ionic interfaces of a three-electrolyte pH differential system are studied, and feasible solutions are put forward to further improve the electrochemical performance of such a system. Image 1 • Ionic interfaces of a three-electrolyte pH differential system were studied. • Adding salts into electrolyte solutions was put forward to improve the cell performance. • This work offers new opportunities to develop promising energy technologies. [ABSTRACT FROM AUTHOR]