锂空气电池空气电极功能性粘接剂及复合空气电极制备科学研究

The lithium-air batteries have the highest theoretical energy densities, but there is a greater volume expansion/ shrinkage effect in the air electrode during the subsequent deposition/decomposition of discharge products. The conventional binders empolyed in air electrode are polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), which heve strong binding strength, but low flexibility and moreover are readily swollen, gelled, or dissolved by the nonaqueous liquid electrolytes. As a result of swelling or dissolving, adhesion among electrode particles and of the electrode materials to the current collector gradually deteriorated during repeated volume changes along with subsequent deposition/decomposition of the discharge products. The project would propose conductive polymers as the alternative binder for the air electrode. The conductive polymer can overcome disadvantages of the low elasticity, readily swelling, environmental pollution and the low conductivity of the conventional olephobic binder. On one hand, the conductive polymer can strengthen the integrity of the air electrode during the cycle, reduce the volume effect and improve the cycling stability. Conductive polymer as the functuonal binder, on the other hand, can provide an additional channel for the transmission of both the electronic/Li+, thus further improving the capacity and rate properties of the lithium-air battery. The project will investigate the relationship between the conductive polymer composition and electronic / of Li+ conductivity, study the connection of the preparation method to microstructure of the air electrode and estabilish the structure-activity relationship between the composition/binding of conductive polymer as a functional binder and electrochemical performance of the lithium-air battery. It is expected to help to develop high-capacity lithium-air battery cathode, enrich the lithium-air battery electrode preparation technology and establish the theoretical foundation for the development of high-performance large-capacity storage batteries.

锂空气电池是具有最高理论能量密度的二次电池，但由于空气电极存在较大的体积膨胀效应，且目前常规的空气电极粘结剂如聚偏氟乙烯或聚四氟乙烯等的弹性较低，而且容易在有机电解液中发生溶胀、胶凝或溶解，使电极在循环过程中的完整性受到破坏，限制了其应用。本项目提出以导电聚合物作为空气电极的粘结剂，克服常规油溶性粘结剂的低弹性、易溶胀、污染环境与不导电等缺点，以期加强空气电极在循环过程的完整性，降低体积效应，提高其循环稳定性；同时导电聚合物还可以为电子/Li+的传输提供额外的渠道，从而进一步提高空气电池的容量与倍率性能。本项目将深入分析导电聚合物组成与电子/Li+导电性的关系；揭示粘结方式对空气电极微观结构的影响规律；建立导电聚合物粘结剂的组成与结合方式对锂空气电池电化学性能的构效关系，有望研制成功高容量、高倍率锂空气电池正极，丰富锂空气电池电极材料的制备技术，为高性能大容量储能电池的发展奠定基础。

锂空气电池是具有最高理论能量密度的二次电池，但由于空气电极存在较大的体积膨胀效应，且目前常规的空气电极粘结剂如聚偏氟乙烯或聚四氟乙烯等的弹性较低，而且容易在有机电解液中发生溶胀、胶凝或溶解，使电极在循环过程中的完整性受到破坏，限制了其应用。为了克服常规油溶性粘结剂的低弹性、易溶胀、污染环境与不导电等缺点，以期加强空气电极在循环过程的完整性，降低体积效应，提高其循环稳定性，同时导电聚合物还可以为电子/Li+的传输提供额外的渠道，从而进一步提高空气电池的容量与倍率性能。围绕本项目任务规定，采用了传统的化学聚合法制备研究了掺杂离子对聚合物导电性能的影响，利用导电聚合物的电化学性质，通过循环伏安电超声沉积的方法，成功制备了Co3O4-Ppy@Ni催化剂-粘结剂一体化空气电极，并在1000mAh/g限制容量下取得稳定的电化学性能。此方法操作简便快捷，简化了制备工艺的繁复流程；空气电极制备过程中未使用KB，有效地控制了空气电池内部的副反应，使得在30周充放电循环内，Co3O4-Ppy@Ni体系的空气电池具有较好的稳定性及循环可逆性。此外，基于一种常温下制备方法得到了介孔α-MnO2催化剂材料，在保证聚苯胺掺杂稳定性的前提下，获得了比使用传统的PVDF粘结剂的锂空气电池更低的极化电压。在此基础上，采用缓慢聚合的方法制备了掺杂导电态的聚苯胺复合材料，并研究了KB-PANI及CNT-PANI复合材料的空气电池充放电性能，得到的KB-PANI空气电池倍率性能优于传统涂覆KB-PVDF空气电池，同时在一定程度上抑制了空气电池极化电压的增长速率。建立导电聚合物粘结剂的组成与结合方式对锂空气电池电化学性能的构效关系，有望研制成功高容量、高倍率锂空气电池正极，丰富锂空气电池电极材料的制备技术，为高性能大容量储能电池的发展奠定基础。