锂—空气电池钯负载多孔碳材料一体化空气电极研究

发布时间：2018-06-27 14:18

本文选题：锂-空气电池 + 钯负载　；参考：《燕山大学》2014年硕士论文

【摘要】：本文采用硬模板法和电泳技术成功制备了Pd负载的具有多级孔道结构的碳材料(Pd-modified hollow sphere carbon，PHSC)一体化正极。并以该复合材料为研究对象，运用X射线衍射(XRD)、热重分析(TG-DSC)、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)、比表面积分析(BET)、拉曼光谱(Raman)和红外光谱分析(IR)对复合材料进行了表征。运用恒电流充放电、交流阻抗(EIS)和循环伏安(CV)等方法对其电化学性能进行测试和分析，系统的研究了复合材料的形貌、结构和电化学性能。并对放电产物进行了定量分析。经过XRD图谱分析得出Pd颗粒结晶性良好，并成功负载在碳球壳内，TG-DSC测试表明Pd含量为25wt.%。通过SEM可以看出碳球壳已经牢固地沉积在碳纸的框架中。孔分布曲线得出该材料有3nm和20-100nm两种孔道结构，用BET法计算得出该材料的比表面为127m2/g，BJH法测得孔体积为0.22cm3/g。TEM得出Pd粒子的颗粒大小为10-15nm，碳球壳的壁厚为9.19nm。限定放电比容量为3000mAh/g，在300mA/g电流密度下放电，与传统的SP碳和无钯负载碳球壳(HSC)电极相比，PHSC电极的过电位分别降低了300mV和490mV，大幅度提高了能量转换效率。CV测试使该结果得到了证实。用该材料作锂-空气电池的正极在1.5A/g的电流密度下放电比容量可以达到5900mAh/g。限定充放电比容量为1000mAh/g，以300mA/g的电流密度充放电，电池可以循环205次。我们对放电产物进行了SEM表征，，结果发现SP电极的放电产物Li2O2呈圆盘状，而我们制备的PHSC电极的放电产物Li2O2为片状结构，厚度为10nm左右，均匀生长在碳球壳表面。对放电过程中的放电产物予以定量分析，PHSC电极在100次循环之后Li2O2的含量达到81.6%。以Pd负载的多孔碳一体化电极为空气电极，该锂-空气电池性能得到了大幅度提高，这些优异的性能归因于Pd纳米粒子的催化活性与空气电极的孔道结构，设计结构更加合理的空气电极将是锂-空气电池未来发展的一个新方向。
[Abstract]:In this paper, the Pd-modified hollow sphere carbon (PHSC) cathode supported by PD was successfully prepared by hard template method and electrophoretic technique. The composites were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG-DSC), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), specific surface area analysis (BET), Raman spectroscopy (Raman) and infrared spectroscopy (IR). The electrochemical properties of the composites were measured and analyzed by means of constant current charge-discharge, alternating current impedance (EIS) and cyclic voltammetry (CV). The morphology, structure and electrochemical properties of the composites were systematically studied. The discharge products were quantitatively analyzed. XRD analysis showed that the crystallinity of PD particles was good, and the TG-DSC results showed that the PD content was 25 wt.TG-DSC. It can be seen by SEM that the carbon spherical shell has been firmly deposited in the framework of carbon paper. The pore distribution curves show that the material has two kinds of pore structures: 3nm and 20-100nm. The specific surface area of the material is 127m2 / g / g BJH method. The pore volume measured by BJH method is 0.22 cm ~ 3 / g 路TEM. The particle size of PD particles is 10-15 nm and the wall thickness of carbon spherical shell is 9.19 nm. The specific discharge capacity is 3,000 mAh-g, which is discharged at the current density of 300mA/g. Compared with the conventional SP carbon and palladium free carbon spherical shell (HSC) electrodes, the overpotential of PHSC electrode is reduced by 300mV and 490mV, respectively. Using this material as the cathode of lithium-air battery, the discharge specific capacity can reach 5900mAh / g at the current density of 1.5A/g. The limited charge-discharge capacity is 1000mAh / g, and the battery can be recirculated 205 times at the current density of 300mA/g. The discharge products were characterized by SEM. It was found that the discharge product Li _ 2O _ 2 of SP electrode was disk-shaped, while that of discharge product Li _ 2O _ 2 of our prepared electrode was flake structure with thickness of about 10nm, and it grew uniformly on the surface of carbon spherical shell. Quantitative analysis of discharge products during discharge the content of Li _ 2O _ 2 in PHSC electrode reached 81.6 after 100 cycles. The performance of the lithium-air battery was greatly improved by using the porous carbon electrode supported by PD as the air electrode. These excellent properties were attributed to the catalytic activity of PD nanoparticles and the pore structure of the air electrode. The design of air electrode with more reasonable structure will be a new direction in the future development of lithium-air battery.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM911.41;O646.5

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