Bai Lu, Wang Peng, Li Chengyu, Li Na, Chen Xiaoqi, Li Yantao, Xiao Jijun
Hebei Key Laboratory of Flexible Functional Materials, School of Materials Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050000, China.
Institute of Energy Source, Hebei Academy of Sciences, Shijiazhuang 050052, China.
ACS Omega. 2023 May 31;8(23):20272-20282. doi: 10.1021/acsomega.2c07349. eCollection 2023 Jun 13.
The existing in situ preparation methods of solid polymer electrolytes (SPEs) often require the use of a solvent, which would lead to a complicated process and potential safety hazards. Therefore, it is urgent to develop a solvent-free in situ method to produce SPEs with good processability and excellent compatibility. Herein, a series of polyaspartate polyurea-based SPEs (PAEPU-based SPEs) with abundant (PO)(EO)(PO) segments and cross-linked structures were developed by systematically regulating the molar ratios of isophorone diisocyanate (IPDI) and isophorone diisocyanate trimer (tri-IPDI) in the polymer backbone and LiTFSI concentrations via an in situ polymerization method, which gave rise to good interfacial compatibility. Furthermore, the in situ-prepared PAEPU-SPE@D based on the IPDI/tri-IPDI molar ratio of 2:1 and 15 wt % LiTFSI exhibits an improved ionic conductivity of 6.80 × 10 S/cm at 30 °C and could reach 10 orders of magnitude when the temperature was above 40 °C. The Li|LiFePO battery based on PAEPU-SPE@D had a wide electrochemical stability window of 5.18 V, demonstrating a superior interface compatibility toward LiFePO and the lithium metal anode, exhibited a high discharge capacity of 145.7 mAh g at the 100th cycle and a capacity retention of 96.8%, and retained a coulombic efficiency of above 98.0%. These results showed that the PAEPU-SPE@D system displayed a stable cycle performance, excellent rate performance, and high safety compared with PEO systems, indicating that the PAEPU-based SPE system may play a crucial role in the future.
固体聚合物电解质（SPEs）现有的原位制备方法通常需要使用溶剂，这会导致工艺复杂且存在潜在安全隐患。因此，迫切需要开发一种无溶剂原位方法来制备具有良好加工性能和优异相容性的SPEs。在此，通过系统调节聚合物主链中异佛尔酮二异氰酸酯（IPDI）和异佛尔酮二异氰酸酯三聚体（三 - IPDI）的摩尔比以及LiTFSI浓度，采用原位聚合法制备了一系列具有丰富（PO）（EO）（PO）链段和交联结构的聚天冬氨酸聚脲基SPEs（PAEPU基SPEs），从而实现了良好的界面相容性。此外，基于IPDI/三 - IPDI摩尔比为2:1和15 wt% LiTFSI原位制备的PAEPU - SPE@D在30°C时离子电导率提高到6.80×10⁻⁴ S/cm，当温度高于40°C时可达到10个数量级。基于PAEPU - SPE@D的Li|LiFePO₄电池具有5.18 V的宽电化学稳定窗口，表明对LiFePO₄和锂金属负极具有优异的界面相容性，在第100次循环时放电容量高达145.7 mAh g⁻¹，容量保持率为96.8%，库仑效率保持在98.0%以上。这些结果表明，与PEO体系相比，PAEPU - SPE@D体系具有稳定的循环性能、优异的倍率性能和高安全性，表明PAEPU基SPE体系在未来可能发挥关键作用。
