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.