Polymer electrolyte having multi-layer structure, and all-solid battery comprising same

A polymer electrolyte for an all-solid battery, having a multi-layer structure is provided. An embodiment of the polymer electrolyte is a polymer electrolyte having a multi-layer structure, which includes a first polymer electrolyte layer and a second polymer electrolyte layer, where the EO:Li molar ratio of a poly(ethylene oxide)(PEO)-based polymer and a lithium salt is different between the first and second polymer electrolyte layers is provided. A solid polymer electrolyte of the present invention in the all-solid battery substantially reduces the interfacial resistance with lithium and the discharge overvoltage, resulting in a sufficient discharge capacity, which improves output characteristics and energy density.