可充电镁碘电池含碘复合材料的制备及其电化学性能研究

发布时间：2018-01-11 22:36

本文关键词：可充电镁碘电池含碘复合材料的制备及其电化学性能研究　出处：《天津理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：科学技术的快速发展,对储能电池的性能提出了新的要求,寻找一种新的清洁、安全、高效的电池体系迫在眉睫。碘作为阴极具有较高的理论容量(211 mAh g-1),以金属锂作为阳极,碘作为阴极的锂碘电池具有较高的能量密度和倍率性能,然而锂在充放电过程中会产生枝晶,使得直接以锂当作阳极的电池体系存在严重的安全问题。金属镁是一种理想的阳极材料,其具有较负的电极电势(-2.36 V vs.NHE),与金属锂相比金属镁具有更高的体积能量密度(3833 mAh cm-3),以金属镁作为阳极,碘作为阴极的镁碘电池体系具有较好的应用前景。本文通过使用β-环糊精和活性碳纤维两种不同的材料来固定碘,研究其作为镁碘电池正极的电化学性能,并进一步讨论了使用双三氟甲烷磺酰亚胺锂(LITFSI)作为电解液添加剂对于镁碘电池体系的影响。首先,我们使用β-环糊精作为固碘材料,通过紫外光谱测试确定了β-环糊精/碘复合物中碘的含量为17%。对β-环糊精/碘复合物进行XPS测试表明复合物中β-环糊精与碘之间的相互作用主要为物理吸附,进行热重分析表明β-环糊精对碘的吸附作用显著提升了碘的热稳定性。以β-环糊精/碘复合物作为正极,金属镁作为负极,一定浓度Mg(ClO4)2的DMSO溶液作为电解液组装电池。对组装的镁碘电池以0.1 C的倍率进行放电,0.2 C的倍率进行充电,初始放电容量为138 mAh g-1,电池循环20周后,放电容量为50 mAh g-1,组装的镁碘电池循环的库伦效率为70%左右。使用β-环糊精碘/复合物作为镁碘电池正极具有价格便宜,制备简单等特点,其在分子级别上对碘的吸附和脱附对于进一步研究镁碘电池的机理有一定的意义。其次,我们使用活性碳纤维作为固碘材料,研究活性碳纤维/碘复合物的电化学性能。使用活性碳纤维/碘复合物作为正极,金属镁作为负极,0.3 mol L-1[Mg(THF)6][AlCl4]2的PYR14TFSI和THF(V:V=1:1)混合液作为电解液组装电池。对组装的镁碘电池进行相应的循环伏安(CV)测试,在所得到的CV曲线上存在两组氧化还原峰,分别对应着I2/I3-和I3-/I-两个氧化还原电对的转化。以0.1 C的倍率进行放电,0.2 C的倍率进行充电,对电池进行充放电测试,初始放电容量为142 mAh g-1,但随着充放电测试的进行,电池的容量存在显著的衰减,第五周时电池的放电容量只有58mAh g-1。使用活性碳纤维/碘复合物作为正极省去了导电添加剂、粘结剂和集流体的使用,简化了制作流程,降低了电池的成本,但是电池的循环性能还需要进一步提升。最后,为了进一步提升镁碘电池的性能,我们使用LITFSI作为电解液中的添加剂,研究电解液含锂盐的镁碘电池的电化学性性能。电池充放电结果表明,其性能要明显优于不含锂盐的体系,初始放电容量为231 mAh g-1,50周循环后容量还能保持在60mAh g-1左右。活性碳纤维具有价格便宜、导电性好、吸碘能力强等特点,以活性碳纤维/碘复合物作为正极的镁碘电池具有良好的应用前景。
[Abstract]:The rapid development of science and technology, puts forward new requirements on the performance of the storage battery, look for a new kind of clean, safe, efficient imminent battery system. The theoretical capacity of iodine as a cathode with high (211 mAh g-1), with lithium metal as anode, energy density and rate capability of iodine as a lithium iodine battery cathode the high, however, will produce lithium dendrite in the process of charge and discharge, the lithium battery anode directly to the system as a serious security problems. Magnesium is a kind of ideal anode material, which has low potential (-2.36 V vs.NHE), compared with the metal lithium magnesium has the advantages of energy higher density (3833 mAh cm-3), with metal magnesium as the anode and cathode of the iodine iodine as magnesium battery system has good application prospects. In this paper, through the use of beta cyclodextrin and activated carbon fiber, two different materials to fixed iodine, Study on the electrochemical properties of magnesium as iodine cell, and further discusses the use of double three methane sulfonyl imide lithium fluoride (LITFSI) as the effects of electrolyte additives for magnesium iodide battery system. Firstly, we use the beta cyclodextrin as solid iodine materials by ultraviolet spectroscopy test to determine the beta cyclodextrin / content compound iodine iodine 17%. XPS test on cyclodextrin / iodine complexes show that the interaction between complexes of cyclodextrin and iodine is mainly physical adsorption, thermogravimetric analysis showed that the adsorption effect of cyclodextrin on iodine significantly improves the thermal stability of iodine in beta. Cyclodextrin / iodine complexes as cathode, magnesium as anode, a certain concentration of Mg (ClO4) 2 DMSO solution as electrolyte battery assembly. The assembly of iodine magnesium battery discharge at 0.1 C rate, 0.2 C rate for charging, the initial discharge capacity was 138 MAh g-1, the battery after 20 cycles, the discharge capacity of 50 mAh g-1, assembled magnesium iodine battery cycle efficiency in Kulun is about 70%. The use of beta cyclodextrin complexes as anode magnesium / refined iodine iodine battery has the advantages of low price, simple preparation and its characteristics, at the molecular level of iodine adsorption and desorption for the further study on the mechanism of magnesium iodine battery has certain significance. Secondly, we use the activated carbon fiber as solid iodine materials, electrochemical properties of activated carbon fiber / iodine complex. Using activated carbon fiber / iodine complexes as cathode, magnesium as anode, 0.3 mol L-1[Mg (THF) 6][AlCl4]2 and PYR14TFSI THF (V:V=1:1) mixed solution as the electrolyte battery assembly. The assembly of iodine magnesium battery corresponding cyclic voltammetry (CV) test, the CV curve obtained there are two groups of redox peaks corresponding to I2/I3- and I3-/I- two redox On the transformation. The discharge at 0.1 C rate, 0.2 C rate for charging, charging and discharging test of battery, the initial discharge capacity of 142 mAh g-1, but with the charge and discharge test, the battery capacity has significant attenuation, the discharge capacity of fifth weeks when the battery only 58mAh g-1. using activated carbon the fiber / iodine complex as cathode eliminates the use of conductive additives, binder and current collector, simplifies the production process, reduces the cost of the battery, but the cycle performance of the battery also needs further improvement. Finally, in order to further enhance the performance of magnesium iodine battery, we use LITFSI as an additive in the electrolyte, electrochemical performance of magnesium study on iodine liquid electrolyte battery. The battery charge and discharge. The results show that its performance is better than not containing lithium salt system, the initial discharge capacity of 231 mAh g-1,50 weeks after you can cycle At about 60mAh g-1, activated carbon fiber has the advantages of low price, good conductivity and strong iodine absorption ability. The activated carbon fiber / iodine complex as the positive electrode has good application prospects.

【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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