A polypropylene carbonate-based adaptive buffer layer for stable interfaces of solid polymer lithium metal batteries
MetadataShow full item record
Solid polymer electrolytes (SPEs) have the potential to enhance the safety and energy density of lithium batteries. However, the poor interfacial contact between the lithium metal anode and SPE leads to high interfacial resistance and low specific capacity of a 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 (PPC), poly(ethylene oxide) (PEO) and lithium salt. Viscoelastic properties obtained by rheology experiments indicate that ABL has better liquid-like properties than PEO SPE. The ABL also has higher ionic conductivity than PEO SPE. In the presence of ABL, the interface resistance of the Li/ABL/SPE/LiFePO4 battery only increased 20% after 150 cycles, whereas that of the battery without ABL increased 117%. In addition, since ABL makes a good solid-solid interface contact between Li metal anode and SPE, the battery with ABL delivered an initial discharge specific capacity of >110 mAh/g, which is nearly twice that of the battery without ABL (60 mAh/g). Moreover, ABL is able to keep this good interfacial contact during battery cycling, which makes the Coulombic efficiency of the battery more stable.