Mo Jinshan, Zhang Dongmei, Sun Mingzhe, Liu Lehao, Hu Weihao, Jiang Bing, Chu Lihua, Li Meicheng
School of New Energy, North China Electric Power University, Beijing 102206, China.
Polymers (Basel). 2021 Nov 19;13(22):3992. doi: 10.3390/polym13223992.
Nickel cobalt manganese ternary cathode materials are some of the most promising cathode materials in lithium-ion batteries, due to their high specific capacity, low cost, etc. However, they do have a few disadvantages, such as an unstable cycle performance and a poor rate performance. In this work, polyethylene oxide (PEO) with high ionic conductance and flexibility was utilized as a multifunctional binder to improve the electrochemical performance of LiNiCoMnO cathode materials. Scanning electron microscopy showed that the addition of PEO can greatly improve the adhesion of the electrode components and simultaneously enhance the integrity of the electrode. Thus, the PEO-based electrode (20 wt% PEO in PEO/PVDF) shows a high electronic conductivity of 19.8 S/cm, which is around 15,000 times that of the pristine PVDF-based electrode. Moreover, the PEO-based electrode exhibits better cycling stability and rate performance, i.e., the capacity increases from 131.1 mAh/g to 147.3 mAh/g at 2 C with 20 wt% PEO addition. Electrochemical impedance measurements further indicate that the addition of the PEO binder can reduce the electrode resistance and protect the LiNiCoMnO cathode materials from the liquid electrolyte attack. This work offers a simple yet effective method to improve the cycling performance of the ternary cathode materials by adding an appropriate amount of PEO as a binder in the electrode fabrication process.
镍钴锰三元正极材料因其高比容量、低成本等优点，是锂离子电池中最具潜力的正极材料之一。然而，它们也存在一些缺点，如循环性能不稳定和倍率性能较差。在这项工作中，具有高离子电导率和柔韧性的聚环氧乙烷（PEO）被用作多功能粘结剂，以改善LiNiCoMnO正极材料的电化学性能。扫描电子显微镜显示，添加PEO可以大大提高电极组分的附着力，同时增强电极的完整性。因此，基于PEO的电极（PEO/PVDF中PEO含量为20 wt%）显示出19.8 S/cm的高电子电导率，约为原始PVDF基电极的15000倍。此外，基于PEO的电极表现出更好的循环稳定性和倍率性能，即在2 C下添加20 wt% PEO时，容量从131.1 mAh/g增加到147.3 mAh/g。电化学阻抗测量进一步表明，添加PEO粘结剂可以降低电极电阻，并保护LiNiCoMnO正极材料免受液体电解质的侵蚀。这项工作提供了一种简单而有效的方法，即在电极制备过程中添加适量的PEO作为粘结剂，以提高三元正极材料的循环性能。
