Metal–Organic Framework-Derived NiO@C as a Host for MnO₂ Cathode of Stable Zinc-Ion Batteries

Abstract

MnO2 has been regarded as one of the most promising cathode materials for safe and inexpensive aqueous Zn-ion batteries (AZIBs). However, the severe Mn dissolution upon cycling is a major challenge for their practical application. Herein, we prepared a flexible and carbonaceous host for the MnO2 cathode in the form of metal–organic framework-derived nanoporous carbon decorated with NiO nanoparticles. The NiO nanoparticle-encapsulated carbon as a helpful additive led to a synergistic effect with MnO2. The MnO2 hosted on the flexible support allowed the construction of AZIB with a high capacity (330 mAh/g after 250 cycles at 0.625 A/g) and good cyclic performance (74.4% retention after 1500 cycles at 3.75 A/g). It is believed that the structural transformation of β-MnO2 (MnO2 → Mn2+ → birnessite MnO x ) and the reversible (de)insertion of Zn2+ into NiO (NiO ↔ Zn x NiO) play a key role in the high capacity and cyclic stability of the prepared AZIBs. Our approach holds great promise to design various hosts for MnO2-based cathodes of AZIBs.

Metal–Organic Framework‐Derived MnO/C Nanocomposite with Lamellar Porous Structure for High‐Performance Aqueous Zinc‐Ion Battery

“…For MnO/C-600, MnO/C-700, and MnO/C-800, they were calculated to be 1.10, 0.99, and 0.05, respectively, indicating a low degree of graphitization with more defects present in MnO/C-600 compared to MnO/C-800 or MnO/C-700. [29] The BET results of Mn-BTCA, MnO/C-600, MnO/C-700, and MnO/C-800 are shown in Figure 1d. The surface area of the Mn-BTCA is 68.9 m 2 g À1 .…”

CNT Composite β-MnO2 with Fiber Cable Shape as Cathode Materials for Aqueous Zinc-Ion Batteries

“…At present, the materials widely used in AZIBs mainly include: (1) vanadium-based materials that can promote the insertion and removal of Zn 2+ attributed to it having an open layered structure during charging/discharging processes. Nevertheless, they have poor conductivity and low operating voltage. , (2) Prussian blue analogues that possess a high output voltage and stable structure but low theoretical capacity, poor conductivity, and poor rate capability. , (3) Transition metal sulfides that have a high specific area and abundant interior defects, but instability of the material structure affects their electrochemical properties during charging and discharging. , (4) Manganese-based materials that have multiple valence states, adjustable structure, a high operating voltage, and theoretical capacity, but their structures are unstable and tend to collapse in long-term cycles. , Although a manganese-based positive electrode material in AZIBs has become the most widely used positive electrode material because of its high energy density, large capacity as well as long life, its actual application is restricted due to its poor conductivity, relatively low energy density, and incomplete understanding of the electrochemical reaction mechanism. , Therefore, the methods to strengthen the properties of manganese-based positive materials include carbon coating, metal element doping, morphology refinement, defect engineering, nanostructure engineering, and conductive polymer coatings . For example, Wang et al.…”