石墨烯分散体系的制备及其性能研究

发布时间：2018-01-29 04:10

本文关键词： 石墨插层化合物石墨烯分散液高浓度高收率超级电容器　出处：《华东理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文采用电化学法在无机酸/无机盐水溶液中插层剥离阳极石墨棒,制备了石墨插层化合物(GIC_s),以此为原料,采用液相剥离法制备了高浓度稳定的石墨烯分散液。考察了电解质性质、电解液浓度以及电压对GIC_s层间距和氧化程度的影响;探讨了 GIC_s的结构、分散体系、超声时间、原料浓度等对所制备石墨烯分散液浓度的影响,以及影响石墨烯收率的因素。并得到制备高浓度石墨烯分散液的最优工艺条件。然后以石墨烯作为超级电容器的电极材料,考察不同因素对超级电容器电化学性能的影响。结果如下:1.不同电解质对石墨电化学剥离速率由大到小的顺序是:H_2SO_4、Na_2SO_4、H_3P0_4、(NH_4)_2HP0_4;S042-作为插层阴离子效果较好,由于硫酸的氧化性较强,所制备的GIC_s氧化程度较高。2.在Na_2SO_4溶液中电化学插层剥离,所获得的GIC_s层间距随电压、电解液浓度的升高而增大,同时其剥离速率也提高。当Na_2S0_4电解质浓度为0.5 M、电压为14 V时,电化学剥离最快,产物GIC_s层间距由石墨的0.3358 nm变为0.3381 nm,且含氧量也较低9.04%,是制备石墨烯的良好前躯体。3.在最优工艺条件下,石墨烯分散在NMP中的浓度高达11.47 mg/mL,同时收率为37%;在PVP/水中石墨烯的浓度也达到4.45 mg/mL,收率为14.8%。所获得的石墨烯尺寸都在1 μm左右,层数较少(少于10层),晶型结构较为完整,C/O比值高,缺陷主要是边缘缺陷,沉降实验表明分散液是非常稳定的。4.将石墨烯分散液作为电极活性物质的原料,采用扣式结构制作了石墨烯电极超级电容器,研究了电容器的组装工艺。探讨了电极成型压力、粘结剂用量对电容器电学性能的影响。以10 MP_a成型压力、5 wt.%的粘结剂含量制作电极,在6 mol/LKOH水系电解液中恒电流0.5 A/g下石墨烯超级电容器的比容可以达到162 F/g,能量密度也达到22.5 Wh/kg,并且具有较好的充放电循环性能。
[Abstract]:In this paper, a graphite intercalation compound (GICS) was prepared by intercalating the anode graphite rod in inorganic acid / inorganic salt aqueous solution by electrochemical method, which was used as raw material. High concentration and stable graphene dispersion was prepared by liquid phase stripping method. The effects of electrolyte properties, electrolyte concentration and voltage on the interlayer spacing and oxidation degree of GIC_s were investigated. The effects of the structure of GIC_s, dispersion system, ultrasonic time and concentration of raw materials on the concentration of graphene dispersion were discussed. And the factors affecting the yield of graphene were obtained. The optimum process conditions for preparing high concentration graphene dispersion were obtained. Then graphene was used as electrode material for supercapacitor. The effects of different factors on the electrochemical properties of supercapacitors were investigated. The results are as follows: 1. The order of electrochemical stripping rate of graphite from different electrolytes to graphite is: 1. H3P0 / hp0 / hp0 / hp0 / hp0 / hp0 / hp0 / hp0 / hp0 / hp0. The effect of S042- as an intercalation anion is better. Because of the strong oxidation of sulfuric acid, the oxidation degree of the prepared GIC_s is higher. 2. Electrochemical intercalation exfoliation in Na_2SO_4 solution. The obtained GIC_s layer spacing increases with the increase of voltage and electrolyte concentration, and its stripping rate also increases. When the electrolyte concentration of Na_2S0_4 is 0.5 m, the voltage is 14 V. Electrochemical peeling was the fastest, the GIC_s layer spacing of the product changed from 0.3358 nm of graphite to 0.3381 nm, and the oxygen content was lower than 9.04% nm. Under the optimum conditions, the concentration of graphene dispersed in NMP was up to 11.47 mg / mL, and the yield was 37%. The concentration of graphene in PVP / water was 4.45 mg / mL, and the yield was 14.8%. The size of graphene was about 1 渭 m and the number of layers was less than 10 layers. The crystal structure is relatively complete and the ratio of C / O is high. The defects are mainly marginal defects. The sedimentation experiment shows that the dispersion is very stable .4.The graphene dispersion is used as the raw material of the electrode active substance. The graphene electrode supercapacitor was fabricated with a button-type structure. The assembly process of the capacitor was studied and the electrode forming pressure was discussed. The effect of binder content on the electrical properties of capacitors. The electrode was made with 10 MP_a molding pressure and 5 wt.% binder content. The specific capacity and energy density of graphene supercapacitor can reach 162F / g and 22.5 Wh/kg respectively under the constant current of 0.5 Ag in 6 mol/LKOH aqueous electrolyte. And has better charge and discharge cycle performance.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ127.11

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