Oxygen functionalized interface enables high MnO2 electrolysis kinetics for high energy aqueous Zn-MnO2 decoupled battery

Aqueous Zn-based batteries show great potential in large scale energy storage system due to their low-cost and high-safety merits. However, the practical application of Zn-based batteries is restricted by their inferior energy and power densities, which is resulted from the low output voltage and poor reaction kinetics of cathode materials. To address the above issues, we propose a decoupled aqueous Zn-Mn battery with high-rate and high-voltage by using oxygen functionalized carbon nanotubes (OCNTs) substrate. The functional interface can greatly improve the wettability of the electrode, promote the ion transport capability, and facilitate the rapid deposition/dissolution of MnO2/Mn2+. Consequently, the OCNTs/MnO2 electrode can deliver a high capacity of 9.2 mA h cm(-2) and superior capacity retention of 86.6% at an ultra-high current density of 200 mA cm(-2). When coupled with Zn anode, the Zn//OCNTs/MnO2 decoupled full battery exhibits a high discharge plateau (similar to 2.45 V) and area specific capacity (1.96 mA h cm(-2)) at a current density of 2 mA cm(-2). Moreover, the outstanding peak power density of 13.4 kW kg(-1) and peak energy density of 564.4 W h kg(-1) can be achieved for Zr//OCNTs/MnO2 battery (based on the mass of active material involved in the reaction on the positive and negative electrodes during charge and discharge), far beyond currently reported aqueous electrochemical energy storage devices. This work provides a train of thoughts for the development of high energy and power density aqueous batteries. Published under an exclusive license by AIP Publishing.

Automated summary

An aqueous Zn-Mn battery with high-rate and high-voltage has been proposed using oxygen functionalized carbon nanotubes substrate, addressing the low energy and power densities issue in Zn-based batteries. The battery exhibits superior capacity retention, outstanding power density, and energy density, providing significant insights for the development of high energy and power density aqueous batteries.