Battery Materials Self-Assembled Vanadium Pentoxide (V 2 O 5 ) Hollow Microspheres from Nanorods and Their Application in Lithium-Ion Batteries** An-Min Cao, Jin-Song Hu, Han-Pu Liang, and Li-JunWan* Self-assembled structures with highly specific morphology and novel properties are of great interest to chemists and materials scientists. As a result of rapid advancements in synthetic strategies, highly organized building blocks of metals, [1] semiconductors, [2] copolymers, [3] organic–inorganic hybrid materials, [4] and biominerals [5] have been synthesized by using various methods. However, controlled organization into curved structures from rodlike building blocks remains a challenge. Such a capability is attractive to scientists not only because of its importance in understanding the concept of self-assembly with artifial building blocks but also for its great application potential. [6–9] Vanadium pentoxide (V 2 O 5 ) has been extensively studied as a well-known transition-metal oxide. Various nanostructures of V 2 O 5 , [10] such as nanotubes, nanowires, nanofibers, nanobelts, nanorods, and mesoporous structures have already been synthesized by a variety of methods, including reverse-micelletransition, sol–gel process, hydrothermal treatment, and electrochemical deposition. Nanostructured V 2 O 5 has potential application in the fields of lithium-ion batteries, [10c,d,11] actuators, [10f] catalysis, [12] and sensors. [13] To our knowledge, hollow microspherical V 2 O 5 has not been reported until now although such a structure has long been a focus of research. [14] Herein, we describe a facile method to self-assemble V 2 O 5 nanorods into microspheres. A mediated polyol process was adopted to prepare hollow microspherical V 2 O 5 , in which ethylene glycol (EG) is treated with a metal salt in the presence of poly(vinylpyrrolidone) (PVP). Such a method was previously used to obtain metal nanoparticles, nanowires (EG as a reductant), [15] and oxide nanowires (EG as a ligand). [16] We now present its use, for the first time, to synthesize hollow microspheres of V 2 O 5 . Using vanadium( iii ) acetylacetonate (acac) as the metal-ion source, we have synthesized hollow microspheres with nanorods on their surface; moreover, the morphologies of such nanorods are [*] A.-M. Cao, J.-S. Hu, H.-P. Liang, Prof. Dr. L.-J. Wan Institute of Chemistry Chinese Academy of Sciences (CAS) Beijing 100080 (China) Fax: (+ 86)106-255-8934 E-mail: wanlijun@iccas.ac.cn [**] This work was supported by the National Natural Science Foundation of China (No. 20025308, 20177025, 10028408, and 20121301), the National Key Project on Basic Research (Grant G2000077501). The Chinese Academy of Sciences is gratefully acknowledged. The authors thank Dr. Li Jiang at Schlumberger Doll Research (USA) for his help with the writing of the manuscript. Supporting information for this article is available on the WWW under http://www.angewandte.org or from the author. Angewandte Chemie 4391 Angew. Chem. Int. Ed. 2005, 44, 4391–4395 DOI: 10.1002/anie.200500946 # 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim