Preparation And Electrochemical Performance Of Porous Copper/carbon Nanophase Composite Anode Materials

Lithium-ion batteries（LIBs）, which have high energy density, high operatingvoltage, wide operating temperature range, long cycle life, no memory effect, lightweight, etc., have been extensively used in portable electronic devices, plug-in hybridelectronic vehicles, military equipment and aerospace industry. So far, manyresearchers have studied the lithium intercalation properties of carbon nanotubes aselectrode materials of lithium-ion batteries. In addition, carbon nanotubes can alsodirectly be added to the electrode used as a conductive agent. During manufacturingprocess of conventional electrode, the copper foil current collector was uniformlycoated with an active intercalation electrode materials. The binder added in the activematerilals will decrease the conductivity of the electrode and the poor dispersibility ofthe carbon nanotubes also limits the role of carbon nanotube as a conductive agent.Inthis paper, by using the porous copper as current collector, carbon nanomaterials weredirectly synthesized in porous copper matrix by chemical vapor deposition whichform a continuous three-dimensional conductive network within the electrode material.The method can not only save the binder added, but also disperse the carbonnanomaterials uniformly.Porous copper bulks were prepared by using NaCl and NH4HCO3particles aspore-forming agent. The effects of the shape and amount of the agent on the porosityand pore size of porous copper bulk were investigated. The results indicated that usingthe electrolytic copper powder and NaCl particles as raw material, porous copper witha three-dimensional interconnected network, controllable pore diameter and porositycan be successfully prepared through sintering-desolventizing technology.Carbon nanomaterials were direct synthesized on porous copper matrix by CVDat600℃using Ni/Y as catalyst. Carbon products are the bamboo-like carbonnanotubes and single helical carbon nanofibers when the concentrations are0.001mol/L and0.01mol/L. When the growth temperatures are700℃and800℃, theconcentration of the catalyst Ni/Y is0.001mol/L, the carbon products are the mixtureof single and double helical carbon fiber and noodles-like carbon fiber, respectively.The charge-discharge characteristics, cycle performance and rate dischargecapability were tested for the carbon/porous copper composite electrode containingcarbon nanophase with various morphologies. The results show that the porou copper/carbon nanomaterials composites electrode with porosity of about81%and thethickness of14μm show excellent electrochemical performance. The bamboo-likeCNTs and the single helical carbon nanofibers exhibit better electrochemicalperformance then other carbon nanophases. The first discharge capacity of the twosamples are1238.3mAh/g and1402.6mAh/g respectively. The samples exhibit anexcellent capacity of328.9mAh/g, and340.1mAh/g after100cycles at1C.