Yang Haochen, Zhang Yamin, Tennenbaum Michael J, Althouse Zachary, Ma Yao, He Yubin, Wu Yutong, Wu Tzu-Ho, Mathur Anmol, Chen Peng, Huang Yanghang, Fernandez-Nieves Alberto, Kohl Paul A, Liu Nian
Department of Condensed Matter Physics , University of Barcelona , Barcelona 08028 , Spain.
ICREA-Institució Catalana de Recerca i Estudis Avançats , Barcelona 08010 , Spain.
ACS Appl Mater Interfaces. 2019 Aug 7;11(31):27906-27912. doi: 10.1021/acsami.9b08285. Epub 2019 Jul 24.
Solid polymer electrolytes (SPEs) have the potential to enhance the safety and energy density of lithium batteries. However, poor interfacial contact between the lithium metal anode and SPE leads to high interfacial resistance and low specific capacity of the battery. In this work, we present a novel strategy to improve this solid-solid interface problem and maintain good interfacial contact during battery cycling by introducing an adaptive buffer layer (ABL) between the Li metal anode and SPE. The ABL consists of low molecular-weight polypropylene carbonate , poly(ethylene oxide) (PEO), and lithium salt. Rheological experiments indicate that ABL is viscoelastic and that it flows with a higher viscosity compared to PEO-only SPE. ABL also has higher ionic conductivity than PEO-only SPE. In the presence of ABL, the interface resistance of the Li/ABL/SPE/LiFePO battery only increased 20% after 150 cycles, whereas that of the battery without ABL increased by 117%. In addition, because ABL makes a good solid-solid interface contact between the Li metal anode and SPE, the battery with ABL delivered an initial discharge specific capacity of >110 mA·h/g, which is nearly twice that of the battery without ABL, which is 60 mA·h/g. Moreover, ABL is able to maintain electrode-electrolyte interfacial contact during battery cycling, which stabilizes the battery Coulombic efficiency.
固态聚合物电解质（SPEs）有潜力提高锂电池的安全性和能量密度。然而，锂金属负极与SPE之间不良的界面接触会导致电池的界面电阻高和比容量低。在这项工作中，我们提出了一种新颖的策略来改善这种固-固界面问题，并通过在锂金属负极和SPE之间引入自适应缓冲层（ABL），在电池循环过程中保持良好的界面接触。ABL由低分子量聚碳酸丙烯酯、聚环氧乙烷（PEO）和锂盐组成。流变学实验表明，ABL具有粘弹性，并且与仅含PEO的SPE相比，它以更高的粘度流动。ABL也比仅含PEO的SPE具有更高的离子电导率。在存在ABL的情况下，Li/ABL/SPE/LiFePO电池的界面电阻在150次循环后仅增加了20%，而没有ABL的电池的界面电阻增加了117%。此外，由于ABL在锂金属负极和SPE之间形成了良好的固-固界面接触，带有ABL的电池的初始放电比容量>110 mA·h/g，几乎是没有ABL的电池（60 mA·h/g）的两倍。而且，ABL能够在电池循环过程中保持电极-电解质界面接触，这使电池的库仑效率稳定。
