Preparation Of Copper Chalcogenide Hollow Nanomaterials And Their Electrochemical Properties

Due to their low electrical conductivity, slow lithium ion transport rate and largevolume variation associated with repeated lithium ions insertion/extraction processes,transition metal oxide nanomaterials are still limited for wide applications in lithium ionbatteries. One effective approach to solve these issues and improve electrochemicalperformance is to synthesize hollow nanostructures with large specific surface area andshort lithium-ion transport distance. The large surface area endows the metal oxide withmore lithium storage sites and large electrode-electrolyte contact area for high lithiumions flux across the interface; The permeable thin shells provide significantly reducedpaths for both lithium ions and electrons diffusion. Hollow nanostructures are attractivefor providing sufficient buffering space to accommodate the strain associated withlithium uptake, leading to better electrochemical performances. Meanwhile, metalselenide has better conductivity compared with metal oxide. Herein, a chemical etchingroute has been developed to prepare hierarchical hollow structured CuSe andCu2-xSe-coated CuO nanotube array.CuSe with a hierarchical hollow structure formed from nanoplates has beensuccessfully prepared by a replacement/etching method with Cu(OH)2nano-wirebundles as precursors. The large difference between the solubility products of Cu(OH)2and CuSe results in the formation of Cu(OH)2/CuSe core/shell structures asintermediates. The CuSe with a hierarchical hollow structure is obtained when theCu(OH)2core is dissolved in ammonia solution. Use of the CuSe with a hierarchicalhollow structure as electrode material for lithium ion batteries results in enhancedelectrochemical properties, including initial coulombic efficiency and cyclingperformance, compared with use of CuSe nanoparticles. The relatively stable structureof CuSe with a hierarchical hollow structure is believed to be the main reason for theenhanced electrochemical performance.Utilization of well-aligned hybrid one-dimensional hollow nanostructured arrays is apromising strategy toward the development of transition metal oxides as high-cycle-lifestability and high-rate performance electrode materials for lithium ion batteries. Achemical replacement route has been used to prepare well-aligned Cu2-xSe-coated CuOnanotube arrays with400nm in diameter and several micrometers in length based onCu(OH)2nanotube arrays grown on copper substrate as the precursors. As integrated anode for lithium ion batteries, the Cu2-xSe-coated CuO nanotube array on coppersubstrate is capable of delivering a high cycling capacity of764mAh·g-1after100cycles at a current density of0.08mA·cm-2(0.1C) and retaining a discharge capacity of382.5mAh·g-1and94.5mAh·g-1at a current density of10mA·cm-2(12.5C) and20mA·cm-2(25C), respectively, exhibiting superior performance to bare CuO nanotubearray film. The synergistic effect of the successful hybrid integration of the CuOnanotube and the coated Cu2-xSe semiconducting layer significantly contributes to theenhanced electrochemical properties of the Cu2-xSe-coated CuO nanotube array anode.