新型聚合物电解质基固态锂-空气电池复合空气电极构筑研究

The development of solid-state batteries is the best choice for solving the safety and stability of high-specific-energy lithium-air batteries and improving their practicability. At present, there are many problems hindering the development of solid-state lithium-air batteries, and the architecture of porous air electrode is a key factor for improving the battery performances. Our previous research work has revealed that the bicontinuous nanoporous materials can significantly improve the capacity and cycling stability of the air battery. The feasibility of the application of polymer electrolyte in solid-state Li-CO2 battery has been verified. And the formation and decomposition process of discharge product has been observed in real time by in-situ TEM. Therefore, in this project, we will intend to prepare micro-nano hierarchical and bicontinuous nanoporous catalyst materials, and construct the composite air electrode by in-situ polymerization of novel polymer electrolytes that developed in our group. Also we will optimize the material preparation and electrode construction process, and modify the solid-solid interfacial contact to improve the electrochemical performance of air electrode. Furthemore, the electrochemical reaction mechanism and morphology of discharge products in air electrode will be analyzed by in situ technique. The implementation of this project will reveal the construction and efficient utilization of air electrode based on solid polymer electrolyte, build up the electrochemical reaction mechanism of air electrode, and find out the influence of the interface interaction between discharge product and air electrode on the electrochemical performance of air electrode, which can provide the experimental evidences for exploring the new materials and improving the entire performances of solid-state lithium-air batteries.

发展固态电池是解决锂-空气电池安全性和稳定性及提高实用性的最佳选择。目前阻碍固态锂-空气电池发展的问题有很多，其中多孔空气电极构筑是提高电池性能的关键因素。我们在前期研究工作中揭示了三维双连续纳米多孔材料可以提高空气电池容量，验证了聚合物电解质在固态Li-CO2电池的可行性，并采用原位TEM对Li-O2电池中放电产物形成和分解过程进行实时观察。本项目拟制备微纳分级双连续多孔催化剂材料，结合研究组开发的新型聚合物电解质原位构筑复合空气电极，优化材料制备和电极构筑工艺，进行固-固界面修饰，提升空气电极电化学性能，并采用原位技术分析空气电极电化学反应机制和放电产物形态。本项目的实施将揭示基于固态聚合物电解质的空气电极构筑及高效利用途径，构建空气电极电化学反应机制，探明放电产物与空气电极的界面相互作用对电极电化学性能的影响规律，为探索新材料、提高固态锂-空气电池的整体性能提供实验依据。

聚合物电解质基固态锂-空气电池是极具发展和应用前景的高安全和高比能量二次电池，其中聚合物电解质的离子传输能力和电化学窗口、以及复合空气电极的结构对电池性能影响较大。为此，我们开发出软硬分子链段交联共聚的嵌段共聚物电解质，通过比例调整实现对离子电导率、界面相容性、电化学窗口等的调控；开发出高聚物和低聚物复合的新型聚碳酸乙烯亚乙酯聚合物电解质（PVEC-PE），室温离子电导率达2.1mS/cm，电化学稳定窗口为4.5V；通过在聚合前打破不稳定的五元环弱键的分子结构调控策略，把PVEC-PE的电化学窗口提升至4.8V，离子电导率保持1.0mS/cm；通过表面富含羟基的SiO2纳米颗粒与PVEC-PE复合构建局部分子间相互作用力，将复合电解质的电化学稳定窗口提升至5.0V，离子电导率保持1.35mS/cm；制备厚度约为15um的独立自支撑聚合物复合电解质薄膜，具有高离子电导率和宽电化学窗口及良好界面稳定性。设计开发出双连续纳米多孔催化剂材料用于锂-空气电池；构建了MSTP-PE-HMPA-CNTs复合多孔空气电极用于聚合物基锂-氧电池，降低电池充电电压；采用双功能氧化还原介质开发CA/MSTP-BQ复合多孔空气电极，实现聚合物电解质基锂-氧电池高充放电效率和长循环稳定。通过多种分析表征技术探究了聚合物电解质的离子传输机制和复合多孔空气电极电化学反应机制。上述研究工作为设计开发新型聚合物电解质，以及制备高效率复合多孔空气电极提高电池整体性能等提供了实验依据，有助于推动高安全和高比能电化学储能器件的发展。本项目在Nano Energy和Materials Today等期刊发表SCI论文8篇，申请专利5项，培养多名研究生，获得省部级奖励一项。