锂空气电池用聚合物电解质

Lithium-air batteries have been attracted much more attention due to their high theoretical specific energy density, low cost and friendly environment. However, some challenges still limit their practical application. One of these challenges is the lack of stable electrolytes, which can survive nucleophilic attack of superoxide radical. In this proposed project, new stable polymer electrolyte based on lithiated perfluorinated sulfonic polymer matrix was developed for Li-air batteries. First, we will synthesize the perfluorinated sulfonic acid polymers with different chemical structures based on our previous mastered technology. Then, new polymer electrolytes consisted of lithium salts, ionic liquids and the synthesized lithiated perfluorinated sulfonic polymers will be prepared. Next, we will test and evaluate of these polymer electrolytes, optimize their components and structures, and thus obtain the polymer electrolytes with good ionic conductivity, high chemical and electrochemical stability which is suitable for the practical application of Li-air batteries. In addition, new electrode binders based on the lithiated perfluorinated sulfonic polymer will also been synthesized, which will not only reduce the interface resistance between electrode and polymer electrolyte, but also improve the performance of Li-air batteries. Finally, the Li-air batteries with high specific capacity and long cycle life will be demonstrated based on these new polymer electrolytes and electrode binders we developed in this proposed project. It can be expected that the results of this proposed project will lay a solid ground of theoretical research for Li-air batteries.

锂空气电池因其具有高理论能量密度、材料成本低廉、环境友好等优势而受到广泛关注。但目前缺少稳定电解液已成为制约其实用化的主要瓶颈之一。为此，我们提出以全氟磺酸锂聚合物为基材制备出满足锂空气电池使用要求的新型聚合物电解质的思路。在已有研究的基础上，通过设计并合成出具有稳定结构的全氟磺酸聚合物材料，并将其与离子液体和锂盐复合得到聚合物电解质，系统研究聚合物电解质组成、微观结构与性能之间关系，最终得到具有优异稳定性、高电导率的聚合物电解质。我们还将合成出电池电极用全氟磺酸锂聚合物粘结剂，在降低电极与聚合物电解质界面电阻的同时提高电极内锂离子传递速率。基于此，最终制备出高性能、长寿命的锂空气电池，为锂空气电池的实用化打下坚实的理论基础。

锂空气电池因其具有高理论能量密度、材料成本低廉、环境友好等优势而受到广泛关注。但是目前锂-空气电池普遍存在的循环稳定性差、倍率小等关键问题。为此，我们先后开展了以下几方面的工作，以解决锂-空气电池所遇到的关键问题：.1）新型锂-空气电池用液体电解液：a）提出在液体电解液中添加超氧自由基捕捉剂——三氟甲磺酸铈以提高电池性能的新策略。将三氟甲磺酸铈作为添加剂加入到四乙二醇二甲醚电解液中，可显著提高电池循环性能。b）基于不含α氢的酯类溶剂新型液体电解液的研究。研究了基于特戊酸甲酯和特戊酸氯甲酯为溶剂的液体电解液用于锂空气电池的可行性。由于溶剂化学结构中不含α氢，使得新型液体电解液具有优异的耐超氧根离子稳定性能。通过NMR测试发现电解液在锂氧气电池循环后不发生任何分解。c）针对常规电解液体系LiTFSI/G4电池的倍率性能（尤其在大电流密度下）较差的问题，我们提出选用G3（三乙二醇二甲醚）为溶剂可提高锂空气电池的倍率性能。.2）新型锂-空气电池用聚合物电解质：制备了锂化全氟磺酸新型聚合物电解质。该新型聚合物电解质具有良好的机械强度、高室锂离子电导率（10-3 S cm-1），且锂离子迁移数达到0.93，。锂-氧气电池具备良好的电化学可逆性，在限定容量为1000mAh g-1、电流密度为1A g-1下稳定循环100圈而不衰减。.3）新型锂-空气电池用隔膜：利用我们已掌握的表面涂层技术，将具有捕获超氧根离子功能的单宁酸涂覆到Celgard隔膜表面，在不改变隔膜内部结构的同时可显著提高隔膜在电池中的使用寿命。.4）新型锂-空气电池空气电极用聚合物粘结剂：设计并合成出带有锂离子官能团的改性PVDF-HFP聚合物粘结剂。由于牛磺酸锂改性PVDF-HFP具有可传递锂离子的性能，从而可显著提高锂离子电池的倍率性能。.5）新型锂-空气电池空气电极结构设计：我们创新性的提出将具有储锂功能的氟碳加入到空气电池中，制备出氟碳-碳黑杂化空气电极，以改善电池在大电流密度下的倍率性能。