Advancing lithium-air capacitor batteries through redox pair-enabled dual-cathode configurations
Lithium-air capacitor batteries (LACBs) integrate the rapid charge-discharge capability of supercapacitors into conventional lithium-oxygen batteries, significantly enhancing power density. However, their cycling stability remains unsatisfactory. In this study, we incorporated redox mediators (RMs) into an LACB featuring a dual-cathode configuration. This design facilitates sustained electron transfer between the electrode and Li2O2/Oxygen, thereby delaying RM deactivation caused by electrode passivation and improving overall electrochemical performance. The RM-enhanced battery achieved over 250 cycles at 2 mA cm−2 with a limited capacity of 0.5 mAh cm−2, while exhibiting a 0.54 V reduction in charging voltage at 0.1 mA cm−2 compared to the RM-free system. Furthermore, application of an aluminum foil sealing technique enabled a power density of 13.8 mW cm−2 at 6 mA cm−2, overcoming mass transport limitations inherent in open-cell configurations. We also investigated the influence of oxygen barrier films with varying barrier capabilities on LACB performance. Results indicate that films with superior oxygen resistance better maintain a clean capacitor electrode surface, thereby providing more stable electron supply to the RMs and enhancing rate capability and cycling performance. These findings underscore the potential of redox mediators in improving the performance and longevity of LACBs, offering a promising strategy for their future development.