摘要/Abstract
随着新能源产业和储能产业的快速发展，二次电池的安全性和能量密度要求越来越高.而传统的液态锂电池使用易燃的电解液，所以存在较大的安全隐患.因此固态锂电池由于其较高的安全性和能量密度受到越来越多人的关注.目前困扰固态电池应用的主要问题是其离子电导率和电极电解质界面问题.固态电解质是固态电池的关键材料.因此开发高离子电导率的固态电解质是开发固态电池的关键.在本工作中，作者成功通过旋涂法制备聚乙二醇-聚丙烯腈-聚甲基丙烯酸甲酯（PEO-PAN-PMMA）凝胶电解质.PEO-PAN-PMMA聚合物薄膜为均匀透明的，具有较高的吸附率，且热稳定性较好，在380℃下保持稳定.通过浸泡电解液可以得到性能优异的凝胶电解质.该凝胶电解质具有较高的离子电导率，室温离子电导率为0.4 mS/cm，而且电化学窗口较宽，在0～4.2 V之间化学性能较为稳定，界面稳定性较好.组装成Li//PEO-PAN-PMMA凝胶电解质//LiCoO2电池之后，正极首圈放电容量为129.8 mAh/g，循环100周，正极放电容量剩余119.51 mAh/g，在0.1 C、0.2 C、0.5 C和1 C倍率下循环，正极放电容量分别为129.8 mAh/g，99.5 mAh/g，86.1 mAh/g和64 mAh/g.
关键词: 凝胶电解质, 锂金属电池, 旋涂法, PEO-PAN-PMMA, 高安全
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℃. 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 0~4.2 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.
Key words: gel polymer electrolyte, lithium metal battery, spay casting, PEO-PAN-PMMA, high safety
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