MnO2@CeO2 composite cathode for aqueous zinc-ion batteries: enhanced electrical conductivity and stability through Mn-O-Ce bonds

MnO2 cathodes have been limited in rechargeable aqueous Zn-ion batteries (AZIBs), primarily due to their poor electrical conductivity and manganese dissolution. To alleviate these challenges, a critical modification is proposed to form novel Mn-O-Ce bonds by compositing MnO2 with CeO2. In this work, the MnO2@CeO2 composite cathode was synthesized via a hydrothermal reaction and annealing treatment. Wherein, the density functional theory (DFT) calculations reveal that the Mn-O-Ce bond improves the cycling stability of MnO2@CeO2 by mitigating the dissolution of the manganese base. Meanwhile, based on the experimental results, incorporating CeO2 with MnO2 not only endows the metal oxides with outstanding electrochemical performance, but also enhances their electron transfer ability by the d-orbital interaction at the Fermi level. Moreover, the detailed ex situ characterization studies, reaction kinetics analyses and DFT calculations further illustrate the performance enhancement mechanism of the MnO2@CeO2 composite cathode, which possesses a special urchin-like morphology and Mn-O-Ce bonds, delivering a myriad of active reaction sites, stable crystal structures, and impressive ion diffusion characteristics for the intercalation of H+/Zn2+. The optimized Zn//MnO2@CeO2 battery achieves an ultrahigh capacity of 355 mA h g(-1) at 1 A g(-1) and superior durability of 89.68% after 1000 continuous cycles at 1 A g(-1). The above results imply that the MnO2@CeO2 composite is a potential cathode for AZIBs, which may shed new light on further exploration in cathode materials.