蛋黄-蛋壳结构锂离子筛的设计合成及其电化学提锂方法研究

Metal lithium and its compounds, which are widely used in traditional industry, high technology and new energy, are important strategic resources in national economy and national defence construction. The wester Qaidam salt lake, as the representative of our country, is rich magnesium type salt lake, high concentration of magnesium thereby has a great interference on the separation of scattered lithium ions. Based on the preliminary findings, this project intends to design and synthesize a novel high-performance lithium ion-sieve with yolk-shell structure, then research and develop a new electrochemical method for extracting lithium from salt lake brine with high magnesium lithium ratio based on this lithium ion-sieve. This project will systematically study the reaction mechanism of the electrochemical lithium extraction, and reveal the relationship between the composition structure of this new lithium ion-sieve and the electrochemical lithium extraction performance, then create a new technology for extracting lithium from salt lake brine with high magnesium lithium ratio. The project approval and implementation of this project is expected to establish a simple and efficient lithium extraction method and technology, whilst we will get an in-depth understanding of the characteristics and rules of multi-element separation from the salt lake and provide a reference for the efficient separation of Rb, Cs and B isotope etc. scattered elements.

金属锂及其化合物在传统工业、高新技术及新能源领域具有广泛应用，是国民经济和国防建设的重要战略资源。本项目针对我国盐湖镁锂比高提锂困难的问题，设计合成以锂离子筛为核，多孔碳层为壳，且核壳之间留有空腔的新型蛋黄-蛋壳结构锂离子筛，并基于该锂离子筛开发电化学提锂新方法：利用多孔碳壳进行锂和镁的粗分离，核壳间空腔富集锂，锂离子筛核高选择性嵌入锂，从而实现高镁锂比盐湖卤水中锂的高效快速提取。本项目将系统研究电化学提锂的反应机理及关键影响因素，揭示新型锂离子筛组成结构与提锂性能间的关系规律，创建高镁锂比盐湖卤水提锂新方法并开发关键提锂装置。本项目的研究成果，对盐湖卤水中铷、铯、硼等稀散元素的提取也具有借鉴意义。

锂离子电池，特别是动力锂离子电池的快速发展对锂资源的需求急剧增长。本项目针对我国青海盐湖中镁锂比高导致提锂困难的问题，提出电化学提锂新思路。通过对电化学提锂的反应机理及影响因素、电化学提锂体系及装置的构建、其他阳离子对电化学提锂的影响规律、电化学提锂工艺参数的优化等进行系统研究，实现了盐湖锂资源的高效电化学方法提取。确定了以商业尖晶石型锰酸锂LiMn2O4电化学脱锂后得到的λ-MnO2锂离子筛作为工作电极、以银粉作为辅助电极的电化学提锂体系；确定了电化学提锂的电压范围为0.3~1.1 V，以避免Na+、Mg2+、K+、Ca2+等阳离子的共嵌入；采用恒电流充电-间歇式放电的方式进行电化学提锂，以排除其他高浓度阳离子对电化学提锂的影响。最终实现了在高浓度的其他阳离子存在时的电化学提锂，提锂容量达到4 mmol/g以上。采用电化学方法提锂，极大地提高了锂离子筛的交换容量和交换速度，并有效克服传统离子交换吸附法盐酸污染环境、腐蚀设备，淡水及动力消耗大，锂离子筛颗粒易破碎损失等问题。另外，电化学提锂方法可以与盐湖地区丰富的风能、太阳能等新能源有效结合，在提锂过程中实现新能源的存储与转化，具有实际应用前景。本项目工作为我国盐湖锂资源的提取提供了新的途径，对盐湖卤水中铷、铯、硼等稀散元素的提取也具有借鉴意义。