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Study On The Synthesis Of Doped Carbon Material And Its Application In Anode Material For Lithium Ion Battery And Catalyst For Oxygen Reduction Reaction

Posted on:2017-05-03Degree:MasterType:Thesis
Country:ChinaCandidate:Y F ZhanFull Text:PDF
GTID:2271330503467010Subject:Condensed matter physics
Abstract/Summary:PDF Full Text Request
The new carbon materials have shown potential application in the field of energy conversion and storage owing to its special nanostructure, excellent conductivity and good electrochemical performance. Recently, lithium-ion battery has been considered as the best energy storage device of the battery system and fuel cell is regarded as the clean and efficient electrochemical energy conversion device. These two techniques are expected to solve the problems of energy shortage and environmental degradation that the human beings are facing in the 21 st century. This dissertation is focused on the study of the synthesis of new carbon material and its application in the lithium ion battery and oxygen reduction reaction catalyst. The main research contents and conclusions are as follows:(1) The preparation of I-doped graphene and its application in the anode materials for lithium ion battery. The I-doped graphene is successfully prepared by thermal annealing of the mixture of graphite oxide(GO) and iodine. The crystal structure, morphologies and elemental analysis of graphene was studied by XRD, TEM, HRTEM, Raman and XPS. The results indicate that the I-doped graphene shows a high reversible specific capacity of 1690 mAh/g, which is about 2.85 times high than those of bare graphene(593 mAh/g) and 4.54 times higher than the theoretical capacity of commercial graphite(372 mAh/g). In addition, the I-doped graphene exhibits good cyclability for its reversible specific capacity retains 92.6% after 200 cycles. The I-doped graphene also reveals excellent rate performance. At a very high current rate of 25 A/g, I-doped graphene shows a revisable capacity of 153 mAh/g, which doubles that of bare graphene. The superior electrochemical performance of the I-doped graphene is explained by the change of graphene lattice, defects and positive charge density introduced by the doping of I atoms.(2) The preparation and ORR(oxygen reduction reaction) performance of iodine/nitrogen co-doped graphene. By doping graphene with iodine and ammonia, I and N co-doped graphene(ING) nanosheets is prepared. The ING catalysts show excellent ORR performance both in alkaline and acidic medium compared with bare graphene, iodine-doped graphene(IG) and nitrogen-doped graphene(NG). The asprepared catalyst exhibits striking activity in alkaline with an onset potential of 0.945 V(vs. RHE) which is the same with commercial Pt/C catalyst. In acidic media the ING shows a competitive activity. In both alkaline and acidic media the ING has excellent catalytic efficiency(the ORR is four-electron process) and outsanding stability(much better than the commercial Pt/C). The superior ORR performance of the ING can be attributed to the synergetic doping effect of I and N.(3) The study on the influence of nitrogen source and doping sequence on the electrocatalytic activity for oxygen reduction reaction of nitrogen doped carbon materials. The un-doped graphitic carbon(GC), which is prepared by high temperature pyrolysis of low-cost ionexchange resin(D113) at 1100 °C, is employed as the carbon source and the glycine and NH3 are chosen as different nitrogen source to synthesize the nitrogen doped GC. The structural defect of graphitic carbon, total nitrogen content, types of nitrogen species and surface area are different from different nitrogen source and doping sequence. The results indicate that glycine introduces high content of nitrogen to graphitic carbon but NH3 introduces no nitrogen; glycine will not influence the structure of graphitic carbon but NH3 introduces defects. The best catalyst is prepared by heat treat graphitic carbon with glycine at 900 °C first then further heat treated with NH3 at 900 °C.
Keywords/Search Tags:graphene, doping, lithium ion battery, anode material, oxygen reduction reaction, catalytic
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