Three-dimensional Ge/GeO2 shell-encapsulated Nb2O5 nanoparticle assemblies for high-performance lithium-ion battery anodes

We report an efficient nanostructure of three-dimensional germanium/germanium dioxide (Ge/GeO2) shell-encapsulated niobium pentoxide (Nb2O5) nanoparticle assemblies for high-performance Li storage anode materials. The Ge/GeO2-encapsulated Nb2O5 nanoassemblies are prepared via a simple solvothermal synthesis method. The Ge/GeO2 layer binds the surfaces and interfaces of the interconnected Nb2O5 nanoparticle assemblies, presenting as dense and uniform microspheres. The tightly bound Ge/GeO2 layer interconnects the nanoassemblies to provide high capacity and a pathway for Li+ and electron transport. Via the Nb2O5 assemblies, fast Li+ transport kinetics are secured using a pseudocapacitive reaction mechanism during Li+ insertion and extraction, while Ge nanoparticles provide the high specific capacity. As a result, the Ge/GeO2-encapsulated Nb2O5 microspheres deliver a greatly enhanced reversible capacity of 800 mA h g(-1) and excellent high-rate capability. The superior high-performance in Ge/GeO2 -encapsulated Nb2O5 microspheres arises from a synergetic effect between the interconnected microstructure and the highly reversible GeO2 phase. The encapsulated interconnection material design concept allows control of the Ge-based electrode materials composition making it ideal for fabrication of high-performance electrodes in Li-ion batteries. (C) 2020 Elsevier Ltd. All rights reserved.