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A hierarchical spheroidal MnO@C heterogeneous interface as a cathode material for AZIBs and synthesized through a MOF, which exhibits the excellent cycling stability. [Display omitted] Aqueous zinc-ion batteries (AZIBs) have shown great potential as energy storage devices owing to their high energy density, low cost, and low toxicity. Typically, high performance AZIBs incorporate manganese-based cathode materials. Despite their advantages, these cathodes are limited by significant capacity fading and poor rate performance due to the dissolution and disproportionation of manganese. Herein, hierarchical spheroidal MnO@C structures were synthesized from Mn-based metal–organic frameworks, which benefit from a protective carbon layer to prevent manganese dissolution. The spheroidal MnO@C structures were incorporated onto a heterogeneous interface to act as a cathode material for AZIBs, which exhibited excellent cycling stability (160 mAh g−1 after 1000 cycles at 3.0 A g−1), good rate capability (165.9 mAh g−1 at 3.0 A g−1), and appreciable specific capacity (412.4 mAh g−1 at 0.1 A g−1) for AZIBs. Moreover, the Zn2+ storage mechanism in MnO@C was comprehensively investigated using ex-situ XRD and XPS studies. These results demonstrate that hierarchical spheroidal MnO@C is a potential cathode material for high-performing AZIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The functionalized graphene/polyaniline composite cathode showed high specific capacity and excellent rate performance. • A large conductive network was assembled by functionalized graphene and polyaniline. • The formation of -N-Zn-O- structure efficiently enhanced the Zn2+ storage behavior during discharging process. • A novel H+ and Zn2+ insertion mechanism was presented in this work. Polyaniline (PANI) as a typical conductive polymer has been widely applied in cathode materials of aqueous zinc ion battery (AZIB), owing to the features of high electronic conductivity and simple synthesized methods. However, the cycling instability caused of spontaneous deprotonation still limited the extensive application of PANI cathode materials. In this work, a functionalized commercial graphene (MEG) and PANI composite (MGP-1) was successfully assembled by a facile two-step method. When the MGP-1 acted as cathode material in AZIB, it demonstrated a high capacity of 184.5 mAh/g (0.2 A/g) and excellent rate performance of 137.6 mAh/g (3 A/g) compared to the PANI cathode. The corresponding analysis revealed that the boosted electrochemical behavior of MGP-1 was attributed to the large conductive network fabricated by the MEG and PANI, and the formations of -N-Zn-O- structures during discharging process. Moreover, based on the conventional H+ insertion mechanism, this work furtherly provided a H+ and Zn2+ insertion mechanism. In addition, the utilization of cheap and abundant commercial graphene would allow the graphene/polyaniline composite to be a promising cathode material applied in AZIB. [ABSTRACT FROM AUTHOR]

• A three-dimensional mesoporous microsphere structural β-MnO 2 /PPy composite was obtained using a facile hydrothermal method. • The electric PPy nanowires linked each β-MnO 2 nanorods to significantly enhance the energy storage behavior of β-MnO 2. • The total capacity was dominated by the synergistic effect between the diffusion-controlled and capacitive behavior. [Display omitted] Mn-based materials as a cathode have drawn much attention in aqueous zinc-ion batteries (AZIBs) for its advantages of low cost and environmental friendliness. However, the sluggish reaction kinetics and low structural stability still limit the electrochemical application of Mn-based materials. Herein, a β-MnO 2 / polypyrrole (PPy) composite was synthesized using a facile hydrothermal method. It delivered a remarkable specific discharge capacity of 361.8 mAh g−1 at a current density of 0.2 A g−1 and great rate performance compared to pure MnO 2 powder. And morphological and electrochemical characterizations revealed that the enhanced electrochemical performance of β-MnO 2 /PPy composite was mainly attributed to the high conductivity of PPy nanowires and the 3D mesoporous microsphere structure, which was assembled by β-MnO 2 nanorods and PPy nanowires. This article provided a new sight of synthesizing Mn-based materials/conducting polymer composites for high-performance cathode in zinc-ion batteries. [ABSTRACT FROM AUTHOR]