基于多电子反应的金属硼化物负极材料设计、可控制备与表面改性研究

Metal boride air battery based on multi-electron reaction has higher energy density than monometallic air cell, such as lithium-air battery, znic-air battery, magnesium-air battery, et al., and can meet the various needs in many fields. However, the serious corrosion and surface passivation of metal boride anode in alkaline electrolyte has led to low pratical discharge capacity、poor rate performance and short storage life. In this project, a first principle methode is proposed to screen and optimize the metal boride materials, and metal boride anodes with mutiple microstructures and controlled crystal structures are designed and fabricated to improve discharge platform. A high anti-corrosive and high hydroxyl ion conductive layer will be developed to modify the metal boride anode surface, in order to reduce interface resistance and enhance discharge stability. The project will also investigate the relationship between material composition, microstucture and diffusion kinetic properties, study the effect of anode surface modification on battery electrochemical performance, and establish the transportation law of hydroxyl ion in the modification layer. It is expected to help to develop a metal boride anode of high capacity, high rate performance and high stability by the optimization of electrode fabrication process and interface performance, enrich the metal boride air batttery electroe preparation technolgoy and establish a theoretical foundation for the pratical application of high-performance large-capacity metal boride air batttery.

基于多电子反应的金属硼化物空气电池比少电子单金属空气电池（如锂空气电池、锌空气电池、镁空气电池等），具有更高的能量密度，能满足多种领域的实际应用。但是因目前金属硼化物负极在碱性电解液中存在腐蚀现象、表面钝化等问题而导致了实际放电容量有限、倍率性能差、存储寿命短，限制了其应用。本项目提出采用第一性原理筛选和优化硼化物电极材料体系，设计制备具有多种微观结构和晶体结构可控的硼化物负极材料，建立材料组成、微观结构与材料扩散动力学特性关系，提升电池放电平台，开发具有高抗腐蚀性且高OH-导电性的金属硼化物表面修饰层，以降低电极界面电阻，提高电池放电稳定性，研究电极表面改性对电池电化学性能的影响，建立电极界面OH-输运机制。通过金属硼化物电极制备工艺和界面性能优化，有望研制成功具有高容量、高倍率、高稳定性的金属硼化物负极，丰富金属硼化物负极的制备技术，为高性能大容量金属硼化物空气电池的实用化奠定基础。

基于多电子反应的金属硼化物空气电池比少电子单金属空气电池（如锂空气电池、锌空气电池、镁空气电池等），具有更高的能量密度，能满足多种领域的实际应用。但是因目前金属硼化物负极在碱性电解液中存在腐蚀现象、表面钝化等问题而导致了实际放电容量有限、倍率性能差、存储寿命短，限制了其应用。本项目结合理论计算和不同硼化物电极电化学行为研究筛选出具有最高电化学活性的金属硼化钒作为硼化物空气电池的负极材料。采用砂磨工艺获得高反应活性的纳米硼化钒粉体，然后通过原位包覆技术（具有两性离子的聚多巴胺包覆层、具有OH-离子传导率的镍铁双金属氢氧化物修饰层）进一步提高了硼化钒的化学稳定性，获得在500mA/g放电电流密度下，放电比容量达到3257mAh/g的硼化钒负极。通过自主设计的三电极电池可视装置及理化性能测试，分析了硼化钒负极不同状态下的产物种类，在此基础上探究了硼化钒电极在碱性电解液中腐蚀机理，并提出了新的阳极电荷转移反应机制。研究结果表明硼化钒在存储和放电过程中不会发生表面钝化，而影响硼化钒电极的放电性能因素是活性物质的面密度、阳极活性物质与电解液的直接接触面积以及碱性电解质中氢氧根离子浓度。最后在空气正极催化剂设计与微结构调控、电解液组分制备与优化、以及电池组装工艺优化的基础上制备了容量超过3Ah，并在0.1C倍率下比容量超过400Wh/kg的硼化物空气电池，为其实用化奠定了基础。