Blending Based PEO-PAN-PMMA Gel Polymer Electrolyte Prepared by Spaying Casting for Solid-state Lithium Metal Batteries

With the fast developing of new energy industry and energy storage, the safety and energy density of secondary batteries is more and more important. The commercial lithium ion batteries contain the organic liquid electrolyte, which is flammable. Therefore, the solid-state lithium metal battery with high safety and energy density attract more and more attentions. However, the low ionic conductivity and high interface resistance hinder the application of solid-state lithium metal batteries. Therefore, the developing of solid-state electrolyte with high ionic conductivity is the key to develop the solid-state lithium metal batteries. Polymer electrolyte films consisting of polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA) and liquid electrolyte were prepared by spay casting and examined in order to obtain the best compromise between high conductivity, homogeneity, dimensional and electrochemical stability. The PEO-PAN-PMMA gel polymer electrolyte (GPE) was got by absorbing the electrolyte for 12 h. The PEO-PAN-PMMA membrane is homogeneous and transparent. PEO-PAN-PMMA membrane is characterized by scanning electron microscope (SEM), thermogravimetric (TG) and X-ray diffraction (XRD). The PEO-PAN-PMMA membrane is stable below 380 degrees C. Although it has two XRD peaks, the films could absorb 59% liquid electrolyte, which is significant. The high ionic conductivity of PEO-PAN-PMMA GPE is examined using electrochemical impedance spectroscopy (EIS) and attended due to the high absorption. And the highest ionic conductivity is 0.4 mS/cm at room temperature. The electrochemical window of the PEO-PAN-PMMA GPE is examined using linear sweeping voltammetry, and the films is stable at 0 similar to 4.2 V. Solid state lithium metal battery using the PEO-PAN-PMMA GPE has a charging capacity of 129.8 mAh/g at first cycle and 119.51 mAh/g at 100th cycle. The capacities of the batteries are 129.8 mAh/g, 99.5 mAh/g, 86.1 mAh/g, 64 mAh/g at 0.1 C, 0.2 C, 0.5 C, 1 C rate, respectively. This work pave the way to rechargeable Li batteries with high safety and long cycle life.