다공성 고분자 보호층을 이용한 균일한 리튬 전착 및 리튬 금속 전극의 안정화

Abstract

Designing the next-generation battery system, both high energy density and guaranteed safety should be considered at the same time. Current Lithium Ion-Battery (LIB) system shows its limit because it cannot satisfy both conditions. Therefore, there has been several researches for decades to develop another system that can replace conventional LIB system. Among them, Lithium metal negative electrode was noted for the ultimate high-capacity electrode (3860mAh/g), due to its low electric potential (-3.04V vs SHE) and low gravimetric density (0.53g/cm3). These attractive points led to continued research on using Lithium metal electrode, and there has been a remarkable progress on applying it on the next-generation battery system. However, because of its intrinsic high-reactivity, constant electrochemical reaction with electrolyte occurs on the electrode surface during charging, which induces loss of active material and electrolyte. Finally, this results in decrease of Coulombic efficiency and capacity fading. What is worse, the uncontrollable dendritic deposition of Lithium makes inner short-circuit, which relates to thermal runaway and explosion hazards. Without the solution for these critical issues, there will remain realistic problems in commercialization of Lithium metal battery despite its ultra-high energy density. Therefore, in the point of safety issues, more profound understanding of interfacial reactions on the Lithium surface is necessary. In this study, we will apply the porous polymer layer that has high affinity with Li+ ion. In the polymer-rich matrix, highly negative charge will make cation-rich phase that can delay the depletion of Li+ ion on the lithium metal surface. At the same time, Inter-connected pores in the porous matrix can help facile Li+ ion conduction than that of existing other dense protective layers. This two different characteristics results in uniform lithium deposition during cycling and increase of electrochemical cell performances.