磷系聚醚高分子合成应用于锂电池中的性能研究
发布时间：2019-01-07 15:44
【摘要】：锂离子电池安全问题是限制其应用推广的重要因素,开发安全性电解质成为目前的研究热点。本文通过固态电解质和电解液阻燃添加剂两个思路设计合成了高安全性的聚醚电解质,并系统研究了其安全性能和电化学性能。主要研究内容如下:(1)以硅甲氧基封端聚环氧丙烷(TSPPG)、二草酸硼酸锂(LiBOB)和聚氧化乙烯(PEO),制备半互穿交联网络的电解质膜TSEO。该方法在不需要添加任何催化剂的情况下可以实现现场交联。扫描电镜图显示表面均匀且无孔聚合物电解质膜成功制备,XRD和DSC表明交联使PEO结晶度降低,加入少量聚碳酸丙烯酯(PC)后,电导率可以与液态电解质相媲美,其室温下电导率可以达到10-3 S/cm,电化学稳点窗口接近4.5 V,LiFePO_4/Li电池以及LiFe_(0.2)Mn_(0.8)PO_4/Li电池有良好的循环和倍率性能。(2)以锂镧锆氧(LLZO)、TSPPG、LiBOB原位交联制备复合电解质,掺杂LLZO纳米颗粒后,电解质膜的模量得到提高,达到29 MPa,可抑制锂枝晶的生长;电解质膜具有良好的柔性,能够适应充放电过程中锂金属负极的体积变化。通过恒流极化实验发现,锂沉积更加均匀,佐证了其有效抑制了锂枝晶的生长。室温下该凝胶电解质电导率为10-3 S/cm,LiFePO_4/Li和LiCoO2/Li电池有良好的循环稳定性,0.5 C电流密度下100圈充放电循环后容量保持率均为90%以上。(3)本研究利用二氯磷酸乙酯和聚乙二醇反应合成聚醚磷酸酯阻燃添加剂EPCP,提高市售电解液阻燃性能,来提高电池安全性。通过凝胶渗透色谱、红外、核磁等手段对EPCP进行结构表征,证明EPCP为低聚物。对添加了EPCP的电解液进行安全性能测试,当添加剂用量为15%时,可抑制电解液燃烧,且对电解液的电导率没有影响,为3*10-3 S/cm。通过TGA和DSC测试证明EPCP可以提高电解液热稳定性。线性电位扫描法测得电解液加入EPCP后分解电压升高。组装Li/LiFePO_4和Li/Li CoO2半电池,添加EPCP后,电解液容量衰减慢,寿命增加,且倍率性能与商用电解液几乎一致。
[Abstract]:The safety of lithium-ion batteries is an important factor limiting its application and popularization. The development of safe electrolytes has become a hot research topic. In this paper, a high safety polyether electrolyte was synthesized by the design of solid electrolyte and electrolyte flame retardant additive, and its safety and electrochemical properties were systematically studied. The main research contents are as follows: (1) Si-methoxy terminated poly (propylene oxide) (TSPPG), lithium oxalate borate (LiBOB) and polyvinyl oxide (PEO), were used to prepare semi-interpenetrating cross-linked network (TSEO.) electrolyte membrane. This method can realize field crosslinking without adding any catalyst. XRD and DSC showed that the crystallinity of PEO was decreased by cross-linking, and the conductivity of PEO was comparable to that of liquid electrolyte after adding a small amount of polycarbonate (PC). The conductivity can reach 10-3 S / cm at room temperature, and the electrochemical stability window is close to 4.5 V. LiFePO_4/Li cells and LiFe_ (0.2) Mn_ (0.8) PO_4/Li batteries have good cycling and rate performance. (2) Lithium lanthanum zirconium oxide (LLZO), TSPPG,LiBOB in situ crosslinked composite electrolytes were prepared. After doped with LLZO nanoparticles, the modulus of electrolyte film was improved, and the growth of lithium dendrite was inhibited by 29 MPa,. The electrolyte film has good flexibility and can adapt to the volume change of lithium metal anode during charge and discharge. The constant current polarization experiment shows that the deposition of lithium is more uniform, which proves that it can effectively inhibit the growth of lithium dendrite. At room temperature, the conductivity of the gel electrolyte is 10 ~ (-3) S / cm ~ (-1) LiFePOs 4 / Li and LiCoO2/Li batteries have good cycling stability. The capacity retention rate of 100 cycles under the current density of 0.5 C was above 90%. (3) the flame retardant additive EPCP, was synthesized by the reaction of ethyl dichlorophosphate and polyethylene glycol to improve the flame retardancy of the electrolyte. To improve battery safety. The structure of EPCP was characterized by gel permeation chromatography, IR and NMR. It was proved that EPCP was an oligomer. The safety performance of the electrolyte added with EPCP was tested. When the additive dosage was 15%, the electrolyte combustion could be inhibited, and the conductivity of the electrolyte was not affected, which was 3 ~ (10 ~ (-3) S / cm ~ (-1). TGA and DSC tests show that EPCP can improve the thermal stability of electrolyte. The decomposition voltage of electrolyte added to EPCP was measured by linear potential scanning method. When the Li/LiFePO_4 and Li/Li CoO2 semiconductors are assembled, the capacity of the electrolyte decreases slowly and the life of the electrolyte increases with the addition of EPCP, and the performance of the electrolyte is almost the same as that of the commercial electrolyte.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ326.5;TM912
本文编号：2403836
[Abstract]:The safety of lithium-ion batteries is an important factor limiting its application and popularization. The development of safe electrolytes has become a hot research topic. In this paper, a high safety polyether electrolyte was synthesized by the design of solid electrolyte and electrolyte flame retardant additive, and its safety and electrochemical properties were systematically studied. The main research contents are as follows: (1) Si-methoxy terminated poly (propylene oxide) (TSPPG), lithium oxalate borate (LiBOB) and polyvinyl oxide (PEO), were used to prepare semi-interpenetrating cross-linked network (TSEO.) electrolyte membrane. This method can realize field crosslinking without adding any catalyst. XRD and DSC showed that the crystallinity of PEO was decreased by cross-linking, and the conductivity of PEO was comparable to that of liquid electrolyte after adding a small amount of polycarbonate (PC). The conductivity can reach 10-3 S / cm at room temperature, and the electrochemical stability window is close to 4.5 V. LiFePO_4/Li cells and LiFe_ (0.2) Mn_ (0.8) PO_4/Li batteries have good cycling and rate performance. (2) Lithium lanthanum zirconium oxide (LLZO), TSPPG,LiBOB in situ crosslinked composite electrolytes were prepared. After doped with LLZO nanoparticles, the modulus of electrolyte film was improved, and the growth of lithium dendrite was inhibited by 29 MPa,. The electrolyte film has good flexibility and can adapt to the volume change of lithium metal anode during charge and discharge. The constant current polarization experiment shows that the deposition of lithium is more uniform, which proves that it can effectively inhibit the growth of lithium dendrite. At room temperature, the conductivity of the gel electrolyte is 10 ~ (-3) S / cm ~ (-1) LiFePOs 4 / Li and LiCoO2/Li batteries have good cycling stability. The capacity retention rate of 100 cycles under the current density of 0.5 C was above 90%. (3) the flame retardant additive EPCP, was synthesized by the reaction of ethyl dichlorophosphate and polyethylene glycol to improve the flame retardancy of the electrolyte. To improve battery safety. The structure of EPCP was characterized by gel permeation chromatography, IR and NMR. It was proved that EPCP was an oligomer. The safety performance of the electrolyte added with EPCP was tested. When the additive dosage was 15%, the electrolyte combustion could be inhibited, and the conductivity of the electrolyte was not affected, which was 3 ~ (10 ~ (-3) S / cm ~ (-1). TGA and DSC tests show that EPCP can improve the thermal stability of electrolyte. The decomposition voltage of electrolyte added to EPCP was measured by linear potential scanning method. When the Li/LiFePO_4 and Li/Li CoO2 semiconductors are assembled, the capacity of the electrolyte decreases slowly and the life of the electrolyte increases with the addition of EPCP, and the performance of the electrolyte is almost the same as that of the commercial electrolyte.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ326.5;TM912
【参考文献】
相关期刊论文 前2条
1 WANG JingLun;LUO Hao;MAI YongJin;ZHAO XinYue;ZHANG LingZhi;;Synthesis of aminoalkylsilanes with oligo(ethylene oxide) unit as multifunctional electrolyte additives for lithium-ion batteries[J];Science China(Chemistry);2013年06期
2 李贺;孔令丽;张莹莹;于申军;梁广川;;锂离子电池电解液阻燃添加剂的研究进展[J];电源技术;2009年09期
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