Rationally designed carbon-encapsulated manganese selenide composites from metal-organic frameworks for stable aqueous Zn-Mn batteries

Aqueous zinc ion batteries (AZIBs) have emerged as promising candidates for large-scale energy storage and small electronic devices due to their environmentally friendly, safe, stable, and cost-effective characteristics. Among various cathode materials, manganese-based compounds, particularly manganese oxides, have garnered special attention for their high energy density, non-toxicity, and low cost. However, currently, reported cathode materials generally exhibit mediocre performance in terms of Zn2- storage kinetics and stability. This work proposes a novel cathode material for AZIBs based on manganese selenide nanoparticles (C@MnSe@GO-x) with graphene oxide (GO) encapsulation and in situ transformation of metal-organic frameworks. Upon activation, the C@MnSe@GO-x material transforms into MnOx, resulting in a high specific capacity of 457.14 mA h g-1 (at 100 mA g-1) in AZIBs. Even after 1500 cycles at 2000 mA g-1, the material maintains 86.15% of its specific capacity. The mechanism of the improved electrochemical performance of the C@MnSe@GO-x based electrode was also investigated by a series of electrochemical tests and ex situ XRD, revealing its transformation mechanism during the initial activation process. This research offers novel insights and theoretical backing for the design and optimization of cathode materials in aqueous zinc-ion batteries, contributing to the advancement of these batteries for practical applications. Electrochemical kinetics unveiled enhanced surface pseudocapacitance in C@MnSe@GO-2, while ex situ XRD exposed the transformation mechanism during activation.