高性能全固态有机羰基锂离子电池的研究

Organic carbonyl compounds as cathode materials of lithium-ion batteries have advantages of high capacities, electrochemical property controllability etc. Unfortunately, these organic materials usually exhibit poor cyclability because of their high solubility in liquid electrolyte. Using solid electrolyte to replace liquid electrolyte can effectively inhibit the dissolution of organic materials. However, the following scientific problems should be solved: ① The discharge voltage of organic carbonyl compounds should be improved (< 3V vs Li/Li+); ② The conductivity of the solid-state electrolytes is low; ③ Interfacial compatibility between solid-state electrolytes and organic cathode materials is poor; ④ The study on the electrons and ions transfer mechanism in organic cathodes during charge-discharge process is lack. In this project, we will design pyridine quinone and pyrimidine quinine-based calix shape carbonyl compounds as cathode materials, which are expected to improve the discharge voltage to ~3.5V and keep high capacity of > 400 mAh g-1. Three-dimensional network solid polymer electrolytes with highly efficient ion-transporting channels will be prepared by esterification of pentaerythritol and dicarboxylic acid. A higher conductivity of 2~3×10-3 S cm-1 can be expected, which is higher than the reported maximum value of 0.5×10-3 S cm-1. At last, we will study the interfacial compatibility between solid-state electrolytes and organic cathode materials as well as electrons and ions transfer mechanism in organic cathodes during charge-discharge process. The above results can supply a new thinking to design organic cathode materials and a new method to prepare solid-state electrolyte with high conductivity. The solution of the above scientific problems is helpful to develop high performance organic lithium-ion batteries.

有机羰基锂离子电池正极材料具有容量高、电化学性能易调控等优点，但其在液态电解质中溶解导致循环性能差。采用固态电解质可以较好的解决其溶解问题，但还存在如下科学问题：①有机羰基正极材料的放电电压有待提高（一般<3V vs Li/Li+）；②固态电解质电导率低；③电解质与电极间界面相容性需改善；④充放电过程中电子/离子转移机理需要研究。针对上述问题，本项目设计了杯状吡啶醌及嘧啶醌羰基正极材料，实现在保持高容量（>400 mAh g-1）的前提下提高放电电压（~3.5V）；设计具有锂离子高速传输通道的三维网状聚合物（季戊四醇酯）固态电解质, 预期电导率达2-3×10-3 S cm-1（目前的最高值为0.5×10-3S cm-1）；最后研究电解质与电极之间的相容性及相关机理。上述研究结果提供了一种新的有机正极材料设计思路及制备高电导率固态电解质的方法，科学问题的解决有助于发展高性能有机锂电池。

有机羰基锂离子电池正极材料具有容量高、电化学性能易调控等优点，但其在液态电解质中溶解导致循环性能差，采用固态电解质可以较好的解决其溶解问题。本项目设计制备了具有锂离子高速传输通道的三维网状聚合物（季戊四醇酯）固态电解质，并对聚合物及电解质进行了优化和表征。利用一系列二元酸和季戊四醇的酯化反应合成聚酯，形成由酯基连接的三维网络结构。三维网络结构可以提供自由的离子通道。此外采用室温质子交换法制备了四元环、五元环、六元环有机无机杂化碳氧盐M(CO)n （M=Li, Na, K; n=4, 5, 6）材料，作为正极材料应用到金属二次电池中，研究其对锂离子、钠离子以及钾离子的储存性能。结果发现四元环碳氧盐在指定的电压区间较难接受阳离子，而五元环盐和六元环盐可以接受一定数目的阳离子。此外，还发现K2C6O6（或K2C5O5）可以作为钾离子的超快嵌入/脱出材料。计算显示K2C6O6是一个拥有0.9 eV窄带隙的半导体，并且钾离子碳氧盐材料相比于钠离子、锂离子碳氧盐材料具有更高的电子电导率，钾离子在电极材料中的扩散速率也更快。