y Rational Design of an Electron/Ion Dual-Conductive Cathode Framework for High-Performance All-Solid-State Lithium Batteries

摘要

All-solid-state lithium batteries (ASSLBs) have been paid increasing attention because of the better security compared with conventional lithium-ion batteries with flammable organic electrolytes. However, the poor ion transport between the cathode materials greatly hinders the capacity performance of ASSLBs. Herein, an electron/ion dual-conductive electrode framework is proposed for superior performance ASSLBs. Highly electronic conductive reduced graphene oxide and carbon nanotubes interconnect with active materials in the cathodes, constructing a three-dimensional continuous electron transport network. The composite electrolyte penetrates into the porous structure of the electrode, forming a consecutive ionic conductive framework. Furthermore, the thin electrolyte film formed on the surface of the cathode effectively lowers the interfacial resistance with the electrolyte membrane. Highly electron/ion conductive electrodes, combined with the polyethylene oxide-Li6.4La3Zr1.4Ta0.6O12 (PEO-LLZTO) composite electrolyte, show excellent capacity performance for both LiFePO4 and sulfur (lithium-sulfur battery) active materials. In addition, the LiFePO4 cathode demonstrates superior capacity performance and rate capability at room temperature. Furthermore, the relationship between the low Coulombic efficiency and Li dendrite growth has been revealed in this work. An effective layer is formed on the surface of Li metal by the simple modification of cupric fluoride (CuF2), which can stabilize the electrolyte/anode interface. Finally, high-performance ASSLBs with high Coulombic efficiency can be achieved.