锂离子电池用新型粘接剂的研制

Development of Novel Adhesives for Lithium-ion Batteries

以丙烯酸叔丁酯(t-BA)、三乳酸乙酯乙烯基硅烷(VELS)为单体,采用原位聚合法制得一种新型聚合物P(t-BA-VELS)。通过红外光谱仪、热重示差仪表征其结构和热稳定性;借助电池循环测试和场发射扫描电镜分别研究了以P(t-BA-VELS)和聚偏氟乙烯(PVDF)为粘接剂所组装电池的电化学性能。结果表明:随着引发剂偶氮二异丁腈用量的增加,P(t-BA-VELS)的黏度先升后降。当引发剂用量为0.5%时,P(t-BA-VELS)的黏度达到最高值,为6.34 Pa·s;随着t-BA与VELS质量比的提高,P(t-BA-VELS)黏度先升后降。当t-BA与VELS的质量比为70∶30时,产物黏度达到最高,为9.99 Pa·s;P(t-BA-VELS)在200~500℃内质量损失开始加快,表明聚合物在200℃时才开始分解,热稳定性良好;采用P(t-BA-VELS)粘接的电池比容量为410 mAh/g,高于采用PVDF粘接的电池(260 mAh/g);经100次充放电循环后,采用P(t-BA-VELS)粘接的电池比采用PVDF的电池放电比容量高出50%,采用PVDF粘接的负极极片出现了较大面积掉粉的情况,且有明显裂纹,而P(t-BA-VELS)粘接的负极极片则无明显的掉粉和裂纹。P(t-BA-VELS)作为锂电池粘接剂时性能优良,有较好的发展前景。

A new polymer P(t-BA-VELS)was prepared by in-situ polymerization with tert-butyl acrylate(t-BA)and ethyl trilactate vinyl silane(VELS)as monomers,whose structure and thermostability were characterized by IR and TGA.The electrochemical performance of the battery with P(t-BA-VELS)and polyvinylidene fluoride(PVDF)as adhesive was studied by battery cycle test and field emission scanning electron microscope.Results showed that the viscosity of P(t-BA-VELS)increased first and then decreased with the increase of azodiisobutyronitrile.When the amount of initiator was 0.5%,the viscosity of P(t-BA-VELS)reached the highest value of 6.34 Pa·s.With the increase of the mass ratio of t-BA to VELS,the viscosity of P(t-BA-VELS)first increased and then decreased.When the mass ratio of t-BA to VELS was 70∶30,the viscosity of the product reached the highest value of 9.99 Pa·s;the mass loss of P(t-BA-VELS)began to accelerate within 200~500℃,which indicated that the polymer began to decompose at 200℃,with good thermal stability.The specific capacity of the battery bonded with P(t-BA-VELS)was 410 mAh/g,which was higher than that of the battery bonded with PVDF(260 mAh/g).After 100 charge discharge cycles,the discharge capacity of the battery bonded with P(t-BA-VELS)was 50%higher than that with PVDF.The negative electrode plate bonded with PVDF had a large area of powder drop and cracks,while the negative plate bonded with P(t-BA-VELS)had no evident powder drop or crack.In conclusion,P(t-BA-VELS)is a promising adhesive for lithium-ion batteries.