Meng Nan, Lian Fang, Wu Luetao, Wang Yue, Qiu Jingyi
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.
Research Institute of Chemical Defense, Beijing 100191, PR China.
ACS Appl Mater Interfaces. 2024 Aug 7;16(31):41487-41494. doi: 10.1021/acsami.4c06551. Epub 2024 Jul 13.
Composite electrolytes have been accepted as the most promising species for solid-state batteries, exhibiting the synergistic advantages of solid polymer electrolytes (SPEs) and solid ceramic electrolytes (SCEs). Unfortunately, the interrupted Li conduction across the SPE and SCE interface hinders the ionic conductivity improvement of composite electrolytes. In our study on a ceramic-rich composite electrolyte (CRCE) membrane composed of borate polyanion-based lithiated poly(vinyl formal) (LiPVFM) and LiAlTi(PO) (LATP) particles, it is found that the strong interaction between the polyanions in LiPVFM and LATP particles results in a uniform distribution of ceramic particles at a high proportion of 50 wt % and good robustness of the electrolyte membrane with a Young's modulus of 9.20 GPa. More importantly, ab initio molecular dynamics simulation and experimental results demonstrate that Li conduction across the SPE and SCE interface is induced by the polyanion-based polymer due to its high lithium-ion transference number and similar Li diffusion coefficient with the SCE. Therefore, the unblocked Li conduction among ceramic particles dominates in the CRCE membrane with a high ionic conductivity of 6.60 × 10 S cm at 25 °C, a lithium-ion transference number of 0.84, and a wide electrochemical stable window of 5.0 V (vs Li/Li). Consequently, the high nickel ternary cathode LiNiMnCoO-based batteries with CRCE deliver a high-rate capability of 135.08 mAh g at 1.0 C and a prolonged cycle life of 100 cycles at 0.2 C between 3.0 and 4.3 V. The polyanion-induced Li conduction across the interface sheds new light on solving composite electrolyte problems for solid-state batteries.
复合电解质已被公认为是固态电池最具前景的材料，展现出固体聚合物电解质（SPEs）和固体陶瓷电解质（SCEs）的协同优势。不幸的是，横跨SPE和SCE界面的锂传导中断阻碍了复合电解质离子电导率的提高。在我们对由硼酸盐聚阴离子基锂化聚乙烯醇缩甲醛（LiPVFM）和LiAlTi(PO)（LATP）颗粒组成的富陶瓷复合电解质（CRCE）膜的研究中，发现LiPVFM中的聚阴离子与LATP颗粒之间的强相互作用导致陶瓷颗粒以50 wt%的高比例均匀分布，且电解质膜具有良好的稳健性，杨氏模量为9.20 GPa。更重要的是，从头算分子动力学模拟和实验结果表明，基于聚阴离子的聚合物因其高锂离子迁移数和与SCE相似的锂扩散系数，诱导了横跨SPE和SCE界面的锂传导。因此，在CRCE膜中，陶瓷颗粒之间畅通无阻的锂传导占主导地位，在25°C下具有6.60×10 S cm的高离子电导率、0.84的锂离子迁移数和5.0 V（相对于Li/Li）的宽电化学稳定窗口。因此，采用CRCE的高镍三元正极LiNiMnCoO基电池在1.0 C下具有135.08 mAh g的高倍率性能，在3.0至4.3 V之间的0.2 C下具有100次循环的长循环寿命。聚阴离子诱导的跨界面锂传导为解决固态电池的复合电解质问题提供了新的思路。
