PMMA基凝胶聚合物电解质在石墨/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)电池中的研究

PMMA based gel polymer electrolyte for graphite/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)lithium-ion battery

凝胶聚合物电解质(GPE)是当前最具商业化应用前景之一的准固态电解质,可以缓解甚至解决锂离子电池存在的漏液、挥发、燃烧等潜在安全问题。本文通过高温原位固化技术制备了一种以甲基丙烯酸甲酯为单体、聚乙二醇二甲基丙烯酸酯为交联剂、双(氟磺酰)亚胺锂为导电盐、碳酸乙烯酯/碳酸甲乙酯混合溶剂为增塑剂的GPE。通过热重分析对聚甲基丙烯酸甲酯(PMMA)基GPE的热力学性质进行了表征,采用计时安培法和电子扫描显微镜研究了PMMA基GPE对Al集流体的稳定性。研究结果表明,PMMA基GPE在室温拥有较高的电导率,达到6.61 mS/cm,同时可以将碳酸酯电解液的挥发温度由100.3℃提高至138.1℃。PMMA基GPE在高电位下对Al箔显示出良好的稳定性,4.3 V vs.Li/Li+以下不会发生铝箔腐蚀,而且在商用石墨/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)软包电池中展现出良好的循环稳定性和容量保持能力,循环1000次后容量保持率为93.4%。

Gel polymer electrolyte(GPE)is one of the most promising electrolytes for commercial application,to mitigate or even tackle the potential safety problems such as leakage,volatilization and combustion of liquid carbonate electrolyte in lithium-ion batteries.Herein,we proposed a new type of GPE comprising methyl methacrylate as monomer,poly(ethylene glycol)dimethacrylate as crosslinking agent,lithium bis(fluorosulfonyl)imide as conductive salt,a mixture of ethylene carbonate/ethyl methyl carbonate as plasticizer,prepared by in situ solidification at elevated temperature.The thermal stability of poly(methyl methacrylate)(PMMA)-based GPE was characterized by thermogravimetric analysis(TGA).The electrhemical behavior of Al foil in the PMMA-based GPE was investigated by using chronoamperometry and scanning electron microscope(SEM).The PMMA-based GPE has a high conductivity of 6.61 mS/cm at room temperature,and exhibits much reduced volatility with 10%weight loss at 138.1℃and 100.3℃for the gel and liquid electrolyte,respectively.Besides,the PMMA-based GPE shows good compatibility with Al foil in the high potential region and does not corrode Al below 4.3 V vs.Li/Li+.Using the PMMA-based GPE,the graphite/LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)pouch cell displays stable cycling performance with 93.4%capacity retention over 1000 cycles.