The Preparation Of Carbon Nanotube Arrays Doped With Nitrogen On Conductive Carbons Papers And Its Application In Lithium-air Batteries

Li-air batteries have attracted more and more attention with ultra-high theoretical energy density of 11140 Wh kg-1. However, the research of Li-air battery is still at the stage of laboratory because there is huge gap between the practical enery density and the the theoretical as well as cycle performance. Among all of the factors that affect the performance of the cell, cathode is the most important part of the cell bacause it is the carrier of the catalyst and bear most of the voltage drop. Currently, research on lithium-air battery cathode materials focused on the carbon materials especially the nitrogen-doped carbon nanotubes(N-CNTs) which have parallel pore structure and catalytic activity. However, the subsrate of N-CNTs are metal sheets or quartz plate which cannot conducing eveen though they have so many advantages that are used to solve the problems of low energy density and insufficient cycle performance.In this paper, densely parked, vertically aligened N-doped carbon nanotubes were synthesis by chemical vapor deposition(CVD) on one side of carbon paper. Then scanning electron microscope(SEM), transmission electron microscopy(TEM), X-ray diffraction spectroscopy(XRD), fourier transform infrared spectroscopy(FTIR) were used to characterize the physical appearance. Cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and the galvanostatic discharge-charge were performed to characterize the chemical properties, and the influence on the performance of lithium-air battery when the different molar ratio of carbon and nitrogen from same nitrogen source and same molar ratio of carbon and nitrogen from different nitrogen source when N-CNTAs as the cathode material.Results are as follows:1. Preparation and characterization of N-CNTAs / carbon paper from different nitrogen contentDensely parked, vertically aligened N-doped carbon nanotubes were synthesis by chemical vapor deposition(CVD) on one side of carbon paper with ethyl-enediamine as nitrogen, xylene as a carbon source and ferrocene as a catalyst. And examining the effents of the molar ratio of carbon and nitrogen(from 10:1 to 50:1)on the micro-morphology of N-CNTAs and the performanc of Li-air battery. It can be conclude that N-CNTAs have smooth walls and uniform diameterthe while the sequence of N-CNTAs prepared by this method is good. The performance of the battery is best and the ratio of the pyridine nitrogen is highest when the ratio is 20:1.2. Preparation and characterization of N-CNTAs/carbon paper from different nitrogen sourceN-CNTAs were prepared by different nitrogen source at the molar ratio of 20:1. These nitrogen source are a-N,N-dimethylformamide, b-diethylamine, c-triethylamine, d-ethylenediamine, e-pyridine andf-acetonitrile. What’s more, the effect of different nitrogen source on the micro-morphology of N-CNTAs/carbon paper and performance of Li-air battery were also been investigated under the ratio of 20:1. The results are shows:(1)XRD results showed that six different nitrogen sources prepared N-CNTAs/carbon paper higher than the degree of graphitization, the order of graphitization degree is: a> f> b> d> e> c.(2) FT-IR results showed that the proportion of nitrogen in the pyridine nitrogen of different materials, the proportion of pyridine nitrogen in six different air cathode is: d> c> e> f> a> b.(3) Charge-discharge test and impedance, cyclic voltammetry test results show that the catalytic activity is best when triethylamine as nitrogen source material, followed by ethylenediamine and pyridine, while DMF, acetonitrile and diethylamine less effective when used as nitrogen source.These conclusions consistent with the results of infrared.Consolidated statement, the catalytic activity has little significant relationship with crystalline of the materials, mainly related to the ratio of pyridine nitrogen, the greater of pyridine nitrogen ratio the higher of the catalytic activity.