Hybrid Ni–Mn–CeOxide Hierarchical HollowArchitectures for High-Performance Supercapacitors

Abstract

Hollow architectures are regarded as latent alternatives to energy storage. Despite various applicable synthesis strategies having been designed to access the hollow architectures of metal oxides, hybrid metal oxides with hollow architectures are seldom achieved because of the challenging synthesis. Here, a simple template strategy for achieving hybrid Ni–Mn–Ce oxide hierarchical hollow architectures is presented. Typically, a Ni–Mn–Ce glycerate precursor with a solid-state structure is first obtained via solvothermal treatment, which then functioned as a reactant template and can be converted to hierarchical hollow architecture intermediates after being treated in N-methylpyrrolidone (NMP) and H₂O solutions. Finally, hybrid Ni–Mn–Ce oxide hierarchical hollow architectures are finally obtained by calcining the intermediates. Exploited as a supercapacitor electrode material, both structural and compositional merits endow the Ni–Mn–Ce oxides with a large specific capacity of 688 C g^–1 at 2.0 A g^–1, striking rate capability, and slight decay after 6000 cycles. As expected, a solid-state asymmetric two-electrode device that is configured with a Ni–Mn–Ce oxide cathode takes an energy density of 78.9 W h kg^–1 at 1199.5 W kg^–1. As the power density increases to 11,998 W kg^–1, the device still shows a high energy density calculated to be 55.3 W h kg^–1. This work not only affords a prospective electrode material for supercapacitors but also offers a synthesis route for preparing hollow architecture hybrid metal oxides.