锂离子电池含氟隔膜材料的制备及其性能研究
发布时间：2018-09-18 14:17
【摘要】：本文实验以三氟氯乙烯（CTFE）、乙烯（Ethylene）、乙酸乙烯酯（VAc）作为聚合反应单体，以偶氮二异丁腈（AIBN）为引发剂，在1,2-二氯-1,1,3,3-五氟丙烷（F-225）溶剂中，用溶液聚合法制备了三氟氯乙烯/乙烯/乙酸乙烯酯三元含氟聚合物。通过傅立叶红外光谱（FT-IR）和核磁氢谱（1HNMR）等方法对它的结构进行了表征。研究了加入单体比例对聚合物产率的影响，结果表明：保持三氟氯乙烯和乙烯的比例不变，随着乙酸乙烯酯加入量的增加，聚合物产率升高，到达一定比例后，产率基本保持不变。然后研究了含氟聚合物的热稳定性能，结果表明：聚合物单体比例CTFE/E/VAc=50/50/0时，聚合物分解温度高达370℃；聚合物单体比例CTFE/E/VAc=45/45/10时，聚合物分解温度达到327℃；聚合物单体比例CTFE/E/VAc=35/35/30时，聚合物分解温度达到260℃。我们还对聚合物进行了结晶度的测试和比较。实验结果证明：制备出的三元共聚物结晶度非常低，它的低结晶度为下面制备薄膜阶段起到了很积极的作用，使得聚合物隔膜有更高的性能。 我们通过相转移方法制备出了三氟氯乙烯/乙烯/乙酸乙烯酯共聚物多孔隔膜。与乙烯-三氟氯乙烯共聚物（ECTFE）相比，新制备的聚合物在室温下容易溶解于大部分溶剂，制作工艺简单，得到的隔膜产物微孔分布均匀，适用于实验室制备和工业生产化。我们对自制的聚合物隔膜进行了一系列的性能表征，并与Celgard公司工业生产的PP隔膜性能进行对比。结果表明：聚合物隔膜和Celgard-PP隔膜对甘油的接触角分别为72.4°和99.7°，证明自制隔膜有良好的亲油性。自制的隔膜对电解液的吸液率达到329%，比Celgard-PP隔膜的吸液率（230%）高出将近100个百分点，隔膜吸液率越高，其电池内阻就越小，电池隔膜的电化学性能越好。聚合物隔膜的拉伸强度为6MPa，断裂伸长率为110%，与Celgard-PP隔膜相比性能较差，分析原因，可能是因为实验室制备隔膜的方法不如工业化生产的工艺成熟。将制好的聚合物隔膜和工业PP隔膜作为电池元件的一部分进行电池组装，组成电池后，在0.2C倍率的条件下循环50次来测试电池充放电循环效率。结果发现，用自制隔膜和工业化PP膜组装完成的电池在50次循环测试后，电池的充放电效率都可以保持90%以上且效率相差不大。证明我们制备的隔膜完全满足电池性能的要求，可以作为锂离子电池隔膜使用。 我们利用静电纺丝技术对制备的三氟氯乙烯/乙烯/乙酸乙烯酯共聚物进行了静电纺丝，并成功的得到了聚合物纤维膜。在10KV高压电压，流速0.2mL/h，接受距离为10cm，，聚合物溶液浓度为15%的条件下，制备出了聚合物纤维膜。通过电镜扫描可以观察到纤维膜纺出的丝分布均匀，没有明显的珠丝，断丝，结块，粘连，聚合物堆积等缺点，纤维直径分布均匀，主要集中在100-300nm左右，微孔和微孔孔径分布均匀，孔径基本集中保持在纳米级，最大孔仅在1μm左右。将制备的纤维膜进行电池组装，测试其充放电循环效率。实验结果发现，电池经过50次循环后，其效率也可以保持在90%以上。证明通过静电纺丝制备的纤维膜可以作为锂离子电池隔膜使用。
[Abstract]:Trifluorochloroethylene/ethylene/vinyl acetate terpolymer was prepared by solution polymerization in 1,2-dichloro-1,1,3,3-pentafluoropropane (F-225) solvent with CTFE, Ethylene and VAc as monomers and AIBN as initiators. The structure of the polymer was characterized by FT-IR and 1HNMR. The effect of monomer ratio on the yield of the polymer was studied. The results showed that the yield of the polymer increased with the addition of vinyl acetate, and remained unchanged after reaching a certain proportion. The thermal stability of fluorinated polymers was studied. The results showed that the decomposition temperature of the polymers reached 370 C when the ratio of CTFE/E/VAc=50/50/0, 327 C when the ratio of CTFE/E/VAc=45/45/10, and 260 C when the ratio of CTFE/E/VAc=35/35/30. The results show that the crystallinity of the copolymers is very low. The low crystallinity of the copolymers plays an active role in the next stage of film preparation, making the polymer diaphragms have higher performance.
Compared with the ethylene-trichloroethylene copolymer (ECTFE), the newly prepared polymer is easy to dissolve in most solvents at room temperature. The preparation process is simple and the pore distribution of the diaphragm product is uniform, which is suitable for laboratory preparation and application. The results show that the contact angles between the polymer diaphragm and the Celgard-PP diaphragm on glycerol are 72.4 degrees and 99.7 degrees respectively, which proves that the self-made diaphragm has good lipophilicity. The electrolyte absorption rate reached 329%, which was nearly 100 percentage points higher than that of Celgard-PP diaphragm (230%). The higher the liquid absorption rate, the smaller the internal resistance and the better the electrochemical performance of the cell diaphragm. Because the method of preparing diaphragm in laboratory is not as mature as that in industrial production, the polymer diaphragm and industrial PP diaphragm are assembled as part of the battery element, and the battery is composed of the polymer diaphragm and the industrial PP diaphragm. After 50 cycles at 0.2C rate, the cycling efficiency of the battery is tested. The results show that the self-made diaphragm and the industrial PP diaphragm are used to test the Cycli After 50 cycles of test, the charge and discharge efficiency of the battery assembled by P-film can be maintained above 90% and the efficiency difference is not significant.
Polymer fiber membranes were prepared by electrospinning of trifluorovinyl chloride/ethylene/vinyl acetate copolymers. The polymer fiber membranes were prepared at 10 KV high voltage, flow rate of 0.2 mL/h, acceptance distance of 10 cm and polymer solution concentration of 15%. It was observed that the fibers were uniformly distributed, without obvious defects such as beads, broken fibers, agglomeration, adhesion and polymer accumulation. The diameter of the fibers was uniformly distributed, mainly concentrated in the range of 100-300 nm. The micropore and micropore size were uniformly distributed. The pore size was basically concentrated in nanometer scale, and the maximum pore size was only about 1 micron. The results show that after 50 cycles, the cell efficiency can be maintained above 90%. It is proved that the fiber membrane prepared by electrospinning can be used as a separator for lithium ion batteries.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912;TQ317
本文编号：2248173
[Abstract]:Trifluorochloroethylene/ethylene/vinyl acetate terpolymer was prepared by solution polymerization in 1,2-dichloro-1,1,3,3-pentafluoropropane (F-225) solvent with CTFE, Ethylene and VAc as monomers and AIBN as initiators. The structure of the polymer was characterized by FT-IR and 1HNMR. The effect of monomer ratio on the yield of the polymer was studied. The results showed that the yield of the polymer increased with the addition of vinyl acetate, and remained unchanged after reaching a certain proportion. The thermal stability of fluorinated polymers was studied. The results showed that the decomposition temperature of the polymers reached 370 C when the ratio of CTFE/E/VAc=50/50/0, 327 C when the ratio of CTFE/E/VAc=45/45/10, and 260 C when the ratio of CTFE/E/VAc=35/35/30. The results show that the crystallinity of the copolymers is very low. The low crystallinity of the copolymers plays an active role in the next stage of film preparation, making the polymer diaphragms have higher performance.
Compared with the ethylene-trichloroethylene copolymer (ECTFE), the newly prepared polymer is easy to dissolve in most solvents at room temperature. The preparation process is simple and the pore distribution of the diaphragm product is uniform, which is suitable for laboratory preparation and application. The results show that the contact angles between the polymer diaphragm and the Celgard-PP diaphragm on glycerol are 72.4 degrees and 99.7 degrees respectively, which proves that the self-made diaphragm has good lipophilicity. The electrolyte absorption rate reached 329%, which was nearly 100 percentage points higher than that of Celgard-PP diaphragm (230%). The higher the liquid absorption rate, the smaller the internal resistance and the better the electrochemical performance of the cell diaphragm. Because the method of preparing diaphragm in laboratory is not as mature as that in industrial production, the polymer diaphragm and industrial PP diaphragm are assembled as part of the battery element, and the battery is composed of the polymer diaphragm and the industrial PP diaphragm. After 50 cycles at 0.2C rate, the cycling efficiency of the battery is tested. The results show that the self-made diaphragm and the industrial PP diaphragm are used to test the Cycli After 50 cycles of test, the charge and discharge efficiency of the battery assembled by P-film can be maintained above 90% and the efficiency difference is not significant.
Polymer fiber membranes were prepared by electrospinning of trifluorovinyl chloride/ethylene/vinyl acetate copolymers. The polymer fiber membranes were prepared at 10 KV high voltage, flow rate of 0.2 mL/h, acceptance distance of 10 cm and polymer solution concentration of 15%. It was observed that the fibers were uniformly distributed, without obvious defects such as beads, broken fibers, agglomeration, adhesion and polymer accumulation. The diameter of the fibers was uniformly distributed, mainly concentrated in the range of 100-300 nm. The micropore and micropore size were uniformly distributed. The pore size was basically concentrated in nanometer scale, and the maximum pore size was only about 1 micron. The results show that after 50 cycles, the cell efficiency can be maintained above 90%. It is proved that the fiber membrane prepared by electrospinning can be used as a separator for lithium ion batteries.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM912;TQ317
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本文编号：2248173
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