Department of Chemical and Biological Engineering , Hanbat National University , 125 Dongseo-daero, Yuseong-gu , Daejeon 34158 , Republic of Korea.
Department of Energy Systems Engineering , Daegu Gyeongbuk Institute of Science and Technology (DGIST) , 333 Techno Jungang-Daero , Daegu 42988 , Republic of Korea.
ACS Appl Mater Interfaces. 2019 Nov 20;11(46):43122-43129. doi: 10.1021/acsami.9b13424. Epub 2019 Nov 6.
Li metal experiences significant morphological changes during operation, resulting in rapid electrochemical performance degradation. In this study, a traditional balloon trick is applied to the Li metal surface to release mechanical stress and hinder morphological changes during operation. Polymer separators directly attach to the Li metal surface using a polymeric adhesive to fabricate a separator/Li metal integrated assembly. The separator/Li metal assembly improves not only the electrochemical performance but also safety issues related to Li metal anodes. This approach has three main advantages: (i) Li metal surface stabilization. The separator/Li metal assembly mechanically stabilize the Li metal surface, resulting in improved rate capability and cycle performance [85.0% of initial discharge capacity (90.2 mAh g) at a 7C condition for rate capability and 87.6% of discharge capacity (95.5 mAh g) at the 220th cycle] compared with the bare Li metal without separator integration [82.6% of initial discharge capacity (84.5 mAh g) at a 3C condition for rate capability and 58.0% of discharge capacity (62.6 mAh g) at the 120th cycle]. (ii) Suitability for high energy density battery implementation. The thickness of the polymeric adhesive is less than 1 μm, which is one-tenth of the coating layer of conventional thermally stable separators, but exhibits similar thermal shrinkage characteristics (0% shrinkage at 140 °C for 30 min). By reducing the thickness of inactive components, a larger volume of active material can be loaded into the battery system to increase the energy density of the battery. (iii) Simple process for mass production. The separator/Li metal integration process ("stick" and "dry") is very simple and can be easily applicable across industries.
锂金属在运行过程中会经历显著的形态变化，导致电化学性能迅速下降。在这项研究中，我们将传统的气球技巧应用于锂金属表面，以释放机械应力并阻碍运行过程中的形态变化。聚合物分离器通过使用聚合物粘合剂直接附着在锂金属表面，从而制造出分离器/锂金属集成组件。该分离器/锂金属组件不仅改善了锂金属阳极的电化学性能，还解决了与安全性相关的问题。这种方法有三个主要优点：（i）稳定锂金属表面。分离器/锂金属组件在机械上稳定了锂金属表面，从而提高了倍率性能和循环性能[在 7C 条件下，初始放电容量（90.2 mAh g）的 85.0%，速率能力和在 220 次循环时的 87.6%放电容量（95.5 mAh g）]，与没有分离器集成的裸锂金属相比[在 3C 条件下，初始放电容量（84.5 mAh g）的 82.6%，速率能力和在 120 次循环时的 58.0%放电容量（62.6 mAh g）]。（ii）适合高能量密度电池的实施。聚合物粘合剂的厚度小于 1μm，是传统热稳定分离器涂层的十分之一，但表现出相似的热收缩特性（在 140°C 下 30 分钟内收缩率为 0%）。通过减少非活性组件的厚度，可以将更多的活性材料装入电池系统中，从而提高电池的能量密度。（iii）大规模生产的简单工艺。分离器/锂金属集成工艺（“粘贴”和“干燥”）非常简单，易于在各个行业中应用。
