Sandwich Structured Metal oxide/Reduced Graphene Oxide/Metal Oxide-Based Polymer Electrolyte Enables Continuous Inorganic-Organic Interphase for Fast Lithium-Ion Transportation

Introducing inorganic fillers into organic poly(ethylene oxide)(PEO)-based electrolyte has attracted substantial attention to enhance its ionic conductivity and mechanical strength, but limited inorganic-organic interphases are always caused by isolated particles agglomeration. Herein, a variety of sandwich structured metal oxide/reduced graphene oxide(rGO)/metal oxide nanocomposites to optimize lithium-ion conduction by interconnected amorphous organic-inorganic interphases in lithium metal batteries, are proposed. With the support of high surface area rGO, the agglomeration of metal oxide particles is precluded, forming continuous amorphous organic-inorganic interphases with stacked layer-by-layer structure, thus creating 3D interconnected lithium-ion transportation channels vertically and laterally. Besides, metal oxide nanoparticles with hydroxyls possess high affinity toward bis(tri-fluoromethanesulfonyl)imide anions by hydrogen bindings between hydroxyls and fluorine and metal-oxygen bonds, releasing more free lithium ions. Consequently, PEO-ZnO/rGO/ZnO electrolyte delivers superior ionic conductivity of 1.02 x 10(-4) S cm(-1) at 25 degrees C and lithium-ion transference number of 0.38 at 60 degrees C. Furthermore, ZnO/rGO/ZnO insertion promotes the formation of LiF-rich stable solid electrolyte interface, endowing Li symmetric cells with long-term cycling stability over 900 hours. The corresponding LiFePO4 cathode possesses a high reversible specific capacity of 130 mAh g(-1) at 0.5C after cycling 300 cycles with a poor capacity fading of 0.05% per cycle.

Automated summary

Introducing inorganic fillers into organic poly(ethylene oxide)(PEO)-based electrolyte has attracted attention for enhancing its ionic conductivity and mechanical strength. However, agglomeration of isolated particles often leads to limited inorganic-organic interphases. This study proposes a variety of metal oxide/reduced graphene oxide(rGO)/metal oxide nanocomposites to optimize lithium-ion conduction in lithium metal batteries, by creating continuous amorphous organic-inorganic interphases with stacked layer-by-layer structure through the support of high surface area rGO.