【摘要】：電解質(zhì)作為鋰電池的關(guān)鍵材料之一,對電池的功率密度、循環(huán)性、安全性等具有重要影響。目前常用的液體電解質(zhì)由于易燃、易漏、易揮發(fā)的特性很容易造成安全問題,而固體聚合物電解質(zhì)是一個很好的解決方案。但是固體聚合物電解質(zhì)存在著電導(dǎo)率較低、鋰離子遷移數(shù)較低的缺點。基于此,本文制備了聚硅氧烷接枝聚氧化乙烯類固體電解質(zhì),并研究了電解質(zhì)的電化學(xué)性能。首先通過硅氫加成反應(yīng)合成了聚氧化乙烯接枝聚硅氧烷。然后將聚合物與雙烯丙基聚乙二醇發(fā)生交聯(lián)反應(yīng),制備了固體聚合物電解質(zhì)(SCPE)。通過交流阻抗法(EIS)研究了鋰鹽濃度對電導(dǎo)率的影響,結(jié)果表明當(dāng)EO:Li為20:1時,電解質(zhì)常溫下電導(dǎo)率達(dá)到1.74×104S/cm。通過線性掃描伏安法(LSV)考察了電解質(zhì)的電化學(xué)穩(wěn)定性,結(jié)果表明電解質(zhì)化學(xué)窗口達(dá)到5V(vs.Li+/Li)。基于此電解質(zhì)的LiFePO4/SPE/Li電池在0.15C倍率下循環(huán)30圈后,電池充放電比容量還有130mAh/g左右。加入丁二腈后,電解質(zhì)的電導(dǎo)率和電化學(xué)窗口均得到提高。為提高鋰離子遷移數(shù),首先合成了一種新型的4-苯乙烯磺酰全氟丁基磺酰亞胺鋰鹽,其中-S02-N(-)-S02-C4F9-的電荷離域化程度較高,與鋰離子之間的作用力弱,可提高可移動的鋰離子數(shù)目。通過硅氫加成反應(yīng)將陰離子和聚氧化乙烯接枝到聚硅氧烷骨架上,然后交聯(lián)成單離子導(dǎo)電固體電解質(zhì)(SPE)。通過核磁和紅外證實了鋰鹽單體和聚合物的結(jié)構(gòu)。通過DSC和TG表征了電解質(zhì)的熱性質(zhì),結(jié)果表明電解質(zhì)具有較低的玻璃化溫度和較高的熱穩(wěn)定性。通過LSV和EIS研究了電解質(zhì)的電化學(xué)性能。當(dāng)EO:Li為28:1時,電解質(zhì)在在30 ℃下電導(dǎo)率為3.77×10-5S/cm。電解質(zhì)電化學(xué)窗口達(dá)到5.2V(vs.Li+/Li)。此外,該聚合物電解質(zhì)的鋰離子遷移數(shù)達(dá)到0.80。
[Abstract]:Electrolyte, as one of the key materials of lithium battery, has an important effect on power density, cycle and safety of the battery. At present, the common liquid electrolyte is easy to cause safety problems because of its flammable, leaky and volatile characteristics. Solid polymer electrolyte is a good solution. However, solid polymer electrolytes have the disadvantages of low conductivity and low lithium ion mobility. Based on this, polysiloxane grafted poly (ethylene oxide) solid electrolyte was prepared and its electrochemical properties were studied. Firstly, polyoxyethylene grafted polysiloxane was synthesized by hydrosilylation. The solid polymer electrolyte (SCPE). Was prepared by crosslinking the polymer with diallyl polyethylene glycol. The influence of lithium salt concentration on conductivity was studied by AC impedance (EIS). The results show that the conductivity of electrolyte reaches 1.74 脳 10 ~ 4 S / cm ~ (-1) at normal temperature when EO:Li is 20:1. The electrochemical stability of electrolyte was investigated by linear scanning voltammetry (LSV). The results showed that the electrolyte chemical window reached 5V (vs.Li / Li). The charge / discharge specific capacity of LiFePO4/SPE/Li battery based on this electrolyte is about 130mAh/g after 30 cycles at 0.15C rate. The conductivity and electrochemical window of the electrolyte increased with the addition of succinonitrile. In order to improve the mobility of lithium ions, a new lithium salt of 4-styrene-sulfonyl perfluorocarbon Ding Ji was synthesized, in which the charge of -S02-N (-) -S02-C4F9- was highly delocalized, and the interaction force between it and lithium ion was weak. The number of removable lithium ions can be increased. The anions and polyoxyethylene were grafted onto the polysiloxane skeleton by hydrosilylation reaction, and then crosslinked to form a single ion conductive solid electrolyte (SPE). The structure of lithium salt monomer and polymer was confirmed by NMR and IR. The thermal properties of the electrolyte were characterized by DSC and TG. The results showed that the electrolyte had lower glass transition temperature and higher thermal stability. The electrochemical properties of electrolytes were studied by LSV and EIS. When EO:Li is 28:1, the conductivity of electrolyte is 3.77 脳 10 ~ (-5) S / cm ~ (-1) at 30 鈩，

本文編號：2379380