Amorphous\nZnO Quantum Dot/Mesoporous Carbon Bubble Composites for a High-Performance\nLithium-Ion Battery Anode

Abstract

Due to its high theoretical\ncapacity (978 mA h g^–1), natural abundance, environmental\nfriendliness, and low cost, zinc\noxide is regarded as one of the most promising anode materials for\nlithium-ion batteries (LIBs). A lot of research has been done in the\npast few years on this topic. However, hardly any research on amorphous\nZnO for LIB anodes has been reported despite the fact that the amorphous\ntype could have superior electrochemical performance due to its isotropic\nnature, abundant active sites, better buffer effect, and different\nelectrochemical reaction details. In this work, we develop a simple\nroute to prepare an amorphous ZnO quantum dot (QDs)/mesoporous carbon\nbubble composite. The composite consists of two parts: mesoporous\ncarbon bubbles as a flexible skeleton and monodisperse amorphous zinc\noxide QDs (smaller than 3 nm) encapsulated in an amorphous carbon\nmatrix as a continuous coating tightly anchored on the surface of\nmesoporous carbon bubbles. With the benefits of abundant active sites,\namorphous nature, high specific surface area, buffer effect, hierarchical\npores, stable interconnected conductive network, and multidimensional\nelectron transport pathways, the amorphous ZnO QD/mesoporous carbon\nbubble composite delivers a high reversible capacity of nearly 930\nmA h g^–1 (at current density of 100 mA g^–1) with almost 90% retention for 85 cycles and possesses a good rate\nperformance. This work opens the possibility to fabricate high-performance\nelectrode materials for LIBs, especially for amorphous metal oxide-based\nmaterials.