Yadav Poonam, Beheshti Seyed Hamidreza, Kathribail Anish Raj, Ivanchenko Pavlo, Mierlo Joeri Van, Berecibar Maitane
MOBI Research Group, Department of Electric Engineering and Energy Technology (ETEC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Polymers (Basel). 2022 Jan 18;14(3):363. doi: 10.3390/polym14030363.
Solid-state batteries (SSBs) are gaining attention as they promise to provide better safety and a higher energy density than conventional liquid electrolyte batteries. Solid polymer electrolytes (SPEs) are promising candidates due to their flexibility providing better interfacial contact between electrodes and the electrolyte. However, SPEs exhibit very low ionic conductivity at ambient temperatures, which prevents their practical use in batteries. Herein, a simple and effective technique of hot press rolling is demonstrated to improve ionic conductivity and, hence, the performance of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)-based solid polymer electrolyte. Applying hot press rolling to the electrolyte membrane induced structural changes in the grain boundaries, which resulted in a reduction in the crystallinity of the material and, hence, an increase in the amorphous phase of the material, which eased the movement of the lithium ions within the material. This technique also improved the surface of the membrane, making it homogeneous and smoother, which resulted in better interfacial contact between the electrodes and electrolyte. Electrochemical tests were carried out on electrolyte membranes treated with and without hot press rolling to evaluate the effect of the treatment. The hot pressed electrolyte membrane showed significant improvements in its ionic conductivity and transference number. The cycling performance of the LFP/Li batteries using a hot press rolled electrolyte was also evaluated, which gave a specific discharge capacity of 134 mAh/g at 0.1 C. These results demonstrate that hot press rolling can have a significant effect on the electrochemical performance of solid polymer electrolytes.
固态电池（SSB）正受到关注，因为它们有望提供比传统液体电解质电池更好的安全性和更高的能量密度。固体聚合物电解质（SPE）因其柔韧性可在电极和电解质之间提供更好的界面接触，是很有前景的候选材料。然而，SPE在环境温度下表现出非常低的离子电导率，这阻碍了它们在电池中的实际应用。在此，展示了一种简单有效的热压轧制技术，以提高离子电导率，从而改善基于聚偏氟乙烯 - 共 - 六氟丙烯（PVDF - HFP）的固体聚合物电解质的性能。对电解质膜进行热压轧制会引起晶界结构变化，这导致材料结晶度降低，进而材料非晶相增加，这使得锂离子在材料内的移动更加容易。该技术还改善了膜的表面，使其均匀且更光滑，从而在电极和电解质之间实现了更好的界面接触。对经过和未经过热压轧制处理的电解质膜进行了电化学测试，以评估该处理的效果。热压后的电解质膜在离子电导率和迁移数方面有显著改善。还评估了使用热压轧制电解质的LFP/Li电池的循环性能，在0.1 C时其比放电容量为134 mAh/g。这些结果表明，热压轧制对固体聚合物电解质的电化学性能有显著影响。
