用于热电池的多孔氧化镁纤维表面改性工艺研究

发布时间：2019-01-16 08:44

【摘要】：热电池是采用固态盐作为电解质的原电池。在实际工作状态下,热电池中的固态电解质因熔融而具有流动性,容易发生泄漏,造成不良影响。因此有必要在电解质中加入一定量的粘接剂抑制熔融电解质盐的流动。多孔氧化镁纤维具有复杂的网络结构和多孔形貌。向电解质中加入多孔氧化镁纤维,其抑制熔盐流动的能力优于同等质量下的传统粘接剂材料。为了进一步提升多孔氧化镁纤维对熔盐流动的抑制能力,提升热电池的电性能,以物理和化学两种方式对多孔氧化镁纤维进行了表面改性。首先采用水热反应法制备了多孔氧化镁纤维,并以此法获得的纤维作为改性的基体材料。化学改性方法采用不同质量的氢氟酸对多孔氧化镁纤维进行了表面腐蚀。物理改性方法使用等离子喷涂的方式在多孔氧化镁纤维表面涂覆上一层氧化铝。向二元电解质体系(LiCl-KCl)和三元电解质体系(Li F-LiCl-Li Br)中,加入化学改性纤维和物理改性纤维作为粘接剂,并从电导率、放电容量、电解质泄露量和形变量几个方面进行了评价。多孔氧化镁纤维进行化学表面改性后,纤维表面留下了氟化镁,同时纤维的比表面积获得了明显的提升,增加了电解质和粘接剂的接触面积,有效降低了电解质的泄露量和形变量。随着改性过程中氢氟酸摩尔量的增加,纤维表面氟化镁的增多,EB粉末的电导率小幅度降低,但是放电容量获得显著提升,总体上获得了更好的电性能。无论在二元或是三元体系电解质体系中,化学改性对流动抑制性和电性能的提升都得到了验证。多孔氧化镁纤维进行物理表面改性后,纤维表面涂覆上一层氧化铝。氧化铝相对于氧化镁,对熔盐具有更好的亲和力,降低了电解质的泄露量和形变量。纤维表面涂覆的氧化铝会小幅降低体系的电导率。但在具有相近电导率的情况下,模型电池具有更大的放电容量,因此总体上的电性能也获得了一定的提升。物理改性对流动抑制能力和电性能的提升,同样也在二元或三元电解质体系中获得了确认。
[Abstract]:Thermal battery is a primary battery using solid salt as electrolyte. Under the actual working condition, the solid electrolyte in the thermal battery has fluidity due to melting, which is easy to leak and cause adverse effects. Therefore, it is necessary to add a certain amount of adhesive to the electrolyte to inhibit the flow of molten electrolyte salt. Porous magnesium oxide fiber has complex network structure and porous morphology. When the porous magnesium oxide fiber was added to the electrolyte, the ability of inhibiting the flux of molten salt was better than that of the traditional adhesive material of the same quality. In order to further enhance the inhibition ability of porous magnesium oxide fiber to molten salt flow and enhance the electrical properties of thermal battery, the surface modification of porous magnesium oxide fiber was carried out by physical and chemical methods. Firstly, porous magnesium oxide fibers were prepared by hydrothermal reaction, and the fibers were used as modified matrix materials. The surface corrosion of porous magnesium oxide fiber was studied by chemical modification method with different quality hydrofluoric acid. The physical modification method is plasma sprayed on the surface of porous magnesium oxide fiber with a layer of alumina. To binary electrolyte system (LiCl-KCl) and ternary electrolyte system (Li F-LiCl-Li Br), chemical modified fiber and physical modified fiber are added as adhesives, and from conductivity, discharge capacity, The electrolyte leakage and shape variables were evaluated. After the chemical surface modification of porous magnesium oxide fiber, magnesium fluoride was left on the surface of the fiber, and the specific surface area of the fiber was obviously improved, and the contact area between electrolyte and adhesive was increased. The leakage and shape variables of electrolyte are reduced effectively. With the increase of the amount of hydrofluoric acid and the increase of magnesium fluoride on the fiber surface, the conductivity of EB powder decreased slightly, but the discharge capacity was improved significantly, and the better electrical properties were obtained as a whole. The enhancement of flow inhibition and electrical properties by chemical modification has been verified in both binary and ternary electrolyte systems. After the physical surface modification of porous magnesium oxide fiber, a layer of alumina was coated on the surface of the fiber. Compared with magnesium oxide, alumina has better affinity to molten salts and reduces electrolyte leakage and shape variables. Alumina coated on the surface of the fiber will slightly reduce the conductivity of the system. But under the condition of similar conductivity, the model battery has larger discharge capacity, so the overall electrical performance has been improved. The enhancement of flow inhibition and electrical properties by physical modification has also been confirmed in binary or ternary electrolyte systems.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM915

【参考文献】