Uniform mesoporous Nb 2 O 5 microspheres with controlled porosity for efficient lithium storage

Mesoporous metal oxides with both extraordinary porosity and functionality have been receiving increasing research attention in catalysis, sensing and various energy-related applications. However, progress in the rational and reliable syntheses of many components is quite alleviated, which severely restricts further potential explorations. Here, we present a facile template-free approach to synthesize a type of uniform mesoporous Nb2O5 microspheres with tunable grain and pore sizes. Such a method conducted in hydrothermal conditions undergoes a simple precursor hydrolysis and crystallite aggregation process, which enables flexible parameter control and is easy for large-scale production. In consequence, the obtained mesoporous Nb2O5 microspheres possess excellent and highly controlled mesoporosity and crystallinity, including large grain sizes (33.5 to 61.7 nm) and uniform pore sizes (7.7 to 45.0 nm). Due to the unique structural features for desirable mass diffusion and electrolyte access, the lithium-ion battery anode utilizing the mesoscopic Nb2O5 materials enables highly reversible pseudocapacitive charge storage, delivering a high specific capacity of 181 mAh·g-1 at 0.05 mA·cm-2 and volumetric capacity of 280 mAh·cm-3 at 2.5 mA·cm-2, good rate capability and long-term 1,000 stable cycles at 2.5 mA·cm-2. Our study affords a convenient toolbox for the synthesis of mesoporous metal oxides, which inspires the development of porous materials toward future technological potentials.