3D structured asymmetric electrolytes for high interface stability and fast Li-ion transport in solid-state Li-metal batteries

Abstract Replacing flammable liquid electrolytes with solid polymer electrolytes is a promising route to improve safety of Lithium (Li)-metal batteries. However, developing a suitable high-performance electrolyte with both high ionic conductivity and interface stability against electrodes remains as a challenge. Herein, we design a poly(propylene carbonate) (PPC)/poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)]-based asymmetric solid electrolyte with a 3D blow-spun Li7La3Zr2O12 (LLZO) framework. The controllable degradation of PPC facilitates the wettability and stability between the electrolyte and Li metal. The P(VDF-HFP) with good electrochemical stability is utilized to match with cathode. With the support of the 3D LLZO Li-ion conductor, the electrolyte displays high ionic conductivity (4.9×10-4 S cm-1 at room temperature). The Li||Li symmetric cells assembled with this electrolyte show a long cycling life of over 2700 h at 100 μA cm-2. The electrolyte also delivers an excellent cycling performance in solid-state LiFePO4||Li batteries (300 cycles with a capacity retention of 91.3 %).