Transition-metal ions intercalation chemistry enabled the manganese oxides-based cathode with enhanced capacity and cycle life for high-performance aqueous zinc-ion batteries.

Abstract

Aqueous zinc-ion batteries (AZIBs) employing mild aqueous electrolytes are recognized for their high safety, cost-effectiveness, and scalability, rendering them promising candidates for large-scale energy storage infrastructure. However, the practical viability of AZIBs is notably impeded by their limited capacity and cycling stability, primarily attributed to sluggish cathode kinetics during electrochemical charge-discharge processes. This study proposes a transition-metal ion intercalation chemistry approach to augment the Zn2+ (de)intercalation dynamics using copper ions as prototypes. Electrochemical assessments reveal that the incorporation of Cu2+ into the host MnO2 lattice (denoted as MnO2-Cu) not only enhances the capacity performance owing to the additional redox activity of Cu2+ but also facilitates the kinetics of Zn2+ ion transport during charge-discharge cycles. Remarkably, the resulting AZIB employing the MnO2-Cu cathode exhibits a superior capacity of 429.4 mA h g-1 (at 0.1 A g-1) and maintains 50% capacity retention after 50 cycles, surpassing both pristine MnO2 (146.8 mA h g-1) and non-transition-metal ion-intercalated MnO2 (MnO2-Na, 198.5 mA h g-1). Through comprehensive electrochemical kinetics investigations, we elucidate that intercalated Cu2+ ions serve as mediators for interlayer stabilization and redox centers within the MnO2 host, enhancing capacity and cycling performance. The successful outcomes of this study underscore the potential of transition-metal ion intercalation strategies in advancing the development of high-performance cathodes for AZIBs.