Li Cheng, Liu Guohua, Wang Kai, Dong Wei, Han Jinlong, Yu Yang, Min Zhiwen, Yang Chunlei, Lu Ziheng
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, P. R. China.
Nano Science and Technology Institute, University of Science and Technology of China, Suzhou 215123, P. R. China.
ACS Appl Mater Interfaces. 2021 Aug 25;13(33):39271-39281. doi: 10.1021/acsami.1c08687. Epub 2021 Aug 10.
Solid-state batteries based on ceramic electrolytes are promising alternatives to lithium-ion batteries with better safety and energy density. While solid electrolytes such as the garnet-type LiLaZrO (LLZO) are chemically stable with lithium metal, their rigidity leads to poor interfacial contact with the cathodes. Nonflammable organic phosphates, however, are characterized by a liquid nature and can immerse the conventional porous cathodes to form a good contact. However, the phosphates are unstable with lithium metal anodes. We design a quasi-solid Janus electrolyte based on the ceramic LLZO and a trimethyl phosphate (TMP) gel which combines the best of both worlds. The electrochemical window of the Janus electrolyte is significantly extended compared with the TMP to accommodate the lithium metal anode. The contact between the cathode and the electrolyte is maintained by the semifluid nature of the TMP gel. A lithium-metal battery with such a Janus electrolyte can stably cycle at room temperature at 1C while still retaining a capacity of 115 mAh g over 100 times. In contrast, the batteries based on LLZO and TMP individually cannot function properly. More importantly, despite the quasi-solid nature, the battery does not contain flammable functional parts and can alleviate the safety concerns of current batteries containing organic-type electrolytes. This work provides a simple but effective strategy for safe, inexpensive, and energy-dense solid-state batteries.
基于陶瓷电解质的固态电池有望成为锂离子电池的替代品，具有更好的安全性和能量密度。虽然石榴石型LiLaZrO（LLZO）等固体电解质与锂金属具有化学稳定性，但其刚性导致与阴极的界面接触不良。然而，不可燃的有机磷酸盐具有液体性质，可以浸入传统的多孔阴极以形成良好的接触。然而，这些磷酸盐与锂金属阳极不稳定。我们基于陶瓷LLZO和磷酸三甲酯（TMP）凝胶设计了一种准固态Janus电解质，它结合了两者的优点。与TMP相比，Janus电解质的电化学窗口显著扩展，以适应锂金属阳极。阴极与电解质之间的接触通过TMP凝胶的半流体性质得以维持。具有这种Janus电解质的锂金属电池在室温下以1C的电流可以稳定循环，同时在100次循环后仍保持115 mAh g的容量。相比之下，基于LLZO和TMP单独的电池不能正常工作。更重要的是，尽管具有准固态性质，但该电池不包含易燃功能部件，可以减轻当前含有有机型电解质的电池的安全担忧。这项工作为安全、廉价且能量密集的固态电池提供了一种简单而有效的策略。
