有機溶劑是鋰離子電池電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)的(de)(de)重(zhong)要組成(cheng)部(bu)分，承擔著(zhu)溶(rong)(rong)解(jie)(jie)(jie)鋰鹽(yan)的(de)(de)重(zhong)要作用(yong)。它對(dui)鋰鹽(yan)的(de)(de)溶(rong)(rong)解(jie)(jie)(jie)度(du)(du)、電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)導(dao)率、電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)循環效率、可(ke)逆容量(liang)、安全性(xing)等(deng)有(you)(you)重(zhong)要影(ying)(ying)響(xiang)。優化有(you)(you)機(ji)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)的(de)(de)組成(cheng)，提高有(you)(you)機(ji)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)導(dao)率，減(jian)小(xiao)極(ji)化，是提高電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)性(xing)能(neng)最(zui)重(zhong)要的(de)(de)途徑之(zhi)一。有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)的(de)(de)介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)直接影(ying)(ying)響(xiang)著(zhu)鋰鹽(yan)的(de)(de)溶(rong)(rong)解(jie)(jie)(jie)和解(jie)(jie)(jie)離(li)過程(cheng)，介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)越(yue)大(da)，鋰鹽(yan)就越(yue)容易溶(rong)(rong)解(jie)(jie)(jie)和解(jie)(jie)(jie)離(li)。有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)的(de)(de)粘(zhan)度(du)(du)則對(dui)離(li)子(zi)的(de)(de)移(yi)動(dong)速(su)度(du)(du)有(you)(you)著(zhu)重(zhong)要的(de)(de)影(ying)(ying)響(xiang)，粘(zhan)度(du)(du)越(yue)小(xiao)，離(li)子(zi)移(yi)動(dong)速(su)度(du)(du)越(yue)快(kuai)。因此鋰離(li)子(zi)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)傾向(xiang)選擇(ze)那(nei)些介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)高、粘(zhan)度(du)(du)小(xiao)的(de)(de)有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)，而在實(shi)際情況(kuang)中，介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)高有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)其(qi)粘(zhan)度(du)(du)必(bi)然(ran)也較大(da)，粘(zhan)度(du)(du)小(xiao)的(de)(de)有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)它的(de)(de)介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)必(bi)然(ran)也較小(xiao)，在實(shi)際的(de)(de)應用(yong)中，一般都是用(yong)介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)大(da)的(de)(de)有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)與粘(zhan)度(du)(du)小(xiao)的(de)(de)有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)混合(he)制成(cheng)介(jie)(jie)電(dian)(dian)(dian)(dian)(dian)(dian)常(chang)數(shu)(shu)(shu)相對(dui)較大(da)，而粘(zhan)度(du)(du)相對(dui)較小(xiao)的(de)(de)混合(he)溶(rong)(rong)劑(ji)(ji)作為鋰離(li)子(zi)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)。因此通過優化有(you)(you)機(ji)溶(rong)(rong)劑(ji)(ji)的(de)(de)組成(cheng)，能(neng)使(shi)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)(jie)(jie)液(ye)(ye)(ye)獲得(de)盡可(ke)能(neng)高的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)導(dao)率。

作為最佳的鋰離(li)子電池電解液溶劑(ji)，應該盡可能滿(man)足以下要求：

（1）熔點(dian)低(di)(di)、沸(fei)點(dian)高、蒸氣壓(ya)低(di)(di)，從而使工(gong)作溫(wen)度(du)范(fan)圍寬；

（2）介電常(chang)數高，黏度低，從而使電導率(lv)高；

鋰離子電池電解(jie)液有機溶(rong)劑的(de)種類：

1、碳酸酯(zhi)類有機溶劑

碳(tan)酸酯是最早(zao)應用于鋰(li)(li)電(dian)池(chi)(chi)工業的有(you)機(ji)溶劑，在鋰(li)(li)電(dian)池(chi)(chi)工業中具有(you)不可替代的地位。鋰(li)(li)電(dian)池(chi)(chi)常用的碳(tan)酸酯類溶劑可分為(wei)環(huan)狀碳(tan)酸酯和(he)線性(xing)碳(tan)酸酯兩類。

一是(shi)環狀碳(tan)(tan)(tan)酸(suan)酯(zhi)，碳(tan)(tan)(tan)酸(suan)乙烯(xi)酯(zhi)（EC）和碳(tan)(tan)(tan)酸(suan)丙(bing)烯(xi)酯(zhi)（PC）是(shi)鋰離子電池電解液(ye)最重(zhong)要的兩種(zhong)環狀碳(tan)(tan)(tan)酸(suan)酯(zhi)類有機溶劑(ji)6]。

PC在(zai)常(chang)(chang)溫(wen)常(chang)(chang)壓下(xia)(xia)(xia)是無色(se)透明、略(lve)帶有(you)(you)芳(fang)香氣味的(de)(de)液(ye)(ye)體，閃點(dian)為(wei)128℃，著火點(dian)為(wei)133℃。PC的(de)(de)熔點(dian)較(jiao)(jiao)低(di)(di)（-49℃），含有(you)(you)它的(de)(de)電(dian)解(jie)液(ye)(ye)即使在(zai)較(jiao)(jiao)低(di)(di)的(de)(de)溫(wen)度下(xia)(xia)(xia)仍具有(you)(you)較(jiao)(jiao)高(gao)(gao)的(de)(de)電(dian)導率。在(zai)PC基電(dian)解(jie)液(ye)(ye)中，鋰離(li)子(zi)嵌入(ru)(ru)石墨(mo)的(de)(de)過程(cheng)中伴隨著PC的(de)(de)共(gong)嵌入(ru)(ru)現象[6]。往往加(jia)(jia)入(ru)(ru)添加(jia)(jia)劑或共(gong)溶(rong)劑，在(zai)石墨(mo)電(dian)極表面形成穩定的(de)(de)SEI膜(mo)，從而抑制PC共(gong)嵌入(ru)(ru)對電(dian)極的(de)(de)破壞。一(yi)般認為(wei)，碳(tan)酸(suan)丙烯(xi)酯(zhi)PC能(neng)夠有(you)(you)效(xiao)地抑制碳(tan)酸(suan)乙(yi)烯(xi)酯(zhi)EC在(zai)低(di)(di)溫(wen)時結晶析出(chu)，能(neng)有(you)(you)效(xiao)提高(gao)(gao)鋰離(li)子(zi)的(de)(de)低(di)(di)溫(wen)性(xing)能(neng)。電(dian)池的(de)(de)高(gao)(gao)低(di)(di)溫(wen)性(xing)能(neng)測試(shi)結果(guo)表明，含PC比不含PC組分(fen)(fen)(fen)電(dian)解(jie)液(ye)(ye)的(de)(de)電(dian)池在(zai)70℃的(de)(de)高(gao)(gao)溫(wen)下(xia)(xia)(xia)和(he)-10℃的(de)(de)低(di)(di)溫(wen)下(xia)(xia)(xia)放電(dian)容量高(gao)(gao)得多EC的(de)(de)結構與PC非(fei)常(chang)(chang)相似，比PC少了一(yi)個甲基，是PC的(de)(de)同系物。EC常(chang)(chang)溫(wen)下(xia)(xia)(xia)為(wei)無色(se)晶體，閃點(dian)160℃，熱(re)(re)安全(quan)性(xing)高(gao)(gao)于(yu)(yu)(yu)PC，黏度略(lve)低(di)(di)于(yu)(yu)(yu)PC，介(jie)電(dian)常(chang)(chang)數(shu)遠高(gao)(gao)于(yu)(yu)(yu)PC，甚至(zhi)高(gao)(gao)于(yu)(yu)(yu)水(shui)，能(neng)夠使鋰鹽充(chong)分(fen)(fen)(fen)溶(rong)解(jie)或電(dian)離(li)，這(zhe)對提高(gao)(gao)電(dian)解(jie)液(ye)(ye)的(de)(de)電(dian)導率非(fei)常(chang)(chang)有(you)(you)利。EC的(de)(de)熱(re)(re)穩定性(xing)較(jiao)(jiao)高(gao)(gao)，加(jia)(jia)熱(re)(re)到200℃才(cai)發生少量分(fen)(fen)(fen)解(jie)，但(dan)堿性(xing)條(tiao)件下(xia)(xia)(xia)容易分(fen)(fen)(fen)解(jie)，可(ke)與甲醇等(deng)發生酯(zhi)交換反(fan)應生成碳(tan)酸(suan)二(er)(er)甲酯(zhi)或乙(yi)二(er)(er)醇。EC的(de)(de)吸混性(xing)高(gao)(gao)于(yu)(yu)(yu)PC，且(qie)可(ke)以任意比與水(shui)混溶(rong)。

二是(shi)線性碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)酯(zhi)(zhi)，常(chang)用(yong)的線性碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)酯(zhi)(zhi)有碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)二甲酯(zhi)(zhi)（DMC）、碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)二乙酯(zhi)(zhi)（DEC）、碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)甲乙酯(zhi)(zhi)（EMC）和(he)(he)碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)甲丙酯(zhi)(zhi)（MPC）等。線性碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)酯(zhi)(zhi)通(tong)常(chang)具有低的黏(nian)度和(he)(he)低的介(jie)電(dian)常(chang)數，不(bu)能單獨用(yong)作鋰離子電(dian)池(chi)電(dian)解液用(yong)優良(liang)溶劑，必(bi)須與環狀(zhuang)碳(tan)(tan)酸(suan)(suan)(suan)(suan)(suan)酯(zhi)(zhi)配合(he)使用(yong)。

DMC常溫(wen)下(xia)(xia)為(wei)無色液體(ti)，閃(shan)點18℃，屬于無毒(du)或(huo)微(wei)毒(du)產品，能與(yu)水(shui)或(huo)醇形成共沸(fei)物。DMC分子結(jie)構(gou)獨特，其(qi)分子結(jie)構(gou)中(zhong)含有(you)羧基、甲(jia)(jia)基和(he)甲(jia)(jia)氧基等官能團，因而具備多(duo)種反(fan)應活性(xing)。DEC的(de)結(jie)構(gou)與(yu)DMC相近，常溫(wen)下(xia)(xia)為(wei)無色液體(ti)，閃(shan)點33℃，略高于DMC，但(dan)毒(du)性(xing)也比DMC強。DEC能溶于酮(tong)、醇、醚、酯等，但(dan)難溶于水(shui)，具有(you)與(yu)乙醚相近的(de)氣味。EMC和(he)MPC是不對稱線(xian)性(xing)碳酸酯，熔點、沸(fei)點、閃(shan)點等與(yu)DMC和(he)DEC的(de)性(xing)質接近。但(dan)其(qi)熱(re)穩定性(xing)較差，容易受(shou)熱(re)或(huo)在堿性(xing)條件下(xia)(xia)發生酯交換反(fan)應生成DMC和(he)DEC。

與環狀碳(tan)酸酯(zhi)相比(bi)，線性碳(tan)酸酯(zhi)具有低的(de)熔點(dian)(dian)、低的(de)黏度和低的(de)介電(dian)(dian)常數，它們能與EC以(yi)任意比(bi)混溶(rong)。EC與DMC混合溶(rong)劑(ji)制得的(de)電(dian)(dian)解液(ye)(ye)同時(shi)受(shou)益于兩(liang)種(zhong)溶(rong)劑(ji)的(de)優(you)點(dian)(dian)，而彌補了對方的(de)缺點(dian)(dian)，并且具有良(liang)好的(de)電(dian)(dian)化學穩(wen)定窗口(kou)l65]。目前，商業化鋰離子電(dian)(dian)池用電(dian)(dian)解液(ye)(ye)溶(rong)劑(ji)都是(shi)由EC與一種(zhong)或兩(liang)種(zhong)線性碳(tan)酸酯(zhi)組(zu)成的(de)混合溶(rong)劑(ji)。

2、羧酸酯類有(you)機溶劑

最重要的環狀羧酸酯(zhi)溶(rong)劑(ji)(ji)是曾用于(yu)一次鋰(li)電(dian)池(chi)的y-丁(ding)內酯(zhi)（BL），液(ye)程溫度(du)相(xiang)對較寬，所形(xing)成(cheng)的電(dian)解(jie)液(ye)的電(dian)導率與(yu)EC+PC電(dian)解(jie)液(ye)相(xiang)近(jin)，與(yu)碳酸酯(zhi)一樣也(ye)能形(xing)成(cheng)鈍化膜(mo)。但BL遇水易(yi)分解(jie)，毒性大，循環效率也(ye)遠低于(yu)碳酸酯(zhi)有機溶(rong)劑(ji)(ji)，在鋰(li)離(li)子(zi)電(dian)池(chi)中很少使用。

線性羧酸(suan)酯(zhi)(zhi)主要有(you)甲(jia)酸(suan)甲(jia)酯(zhi)(zhi)（MF）、乙(yi)酸(suan)甲(jia)酯(zhi)(zhi)（MA）、丁(ding)酸(suan)甲(jia)酯(zhi)(zhi)（MB）和丙酸(suan)乙(yi)酯(zhi)(zhi)（EP）等。這些酯(zhi)(zhi)類的凝固點平均比碳酸(suan)酯(zhi)(zhi)低(di)20~30℃，且(qie)黏度較小，因此能提高電解液的低(di)溫性能。

3、醚類有機溶劑

醚(mi)(mi)類有(you)機溶(rong)劑分(fen)為環狀(zhuang)醚(mi)(mi)、鏈狀(zhuang)醚(mi)(mi)和(he)冠醚(mi)(mi)及(ji)其衍生(sheng)物。環狀(zhuang)醚(mi)(mi)主要包(bao)括四(si)氫(qing)呋喃（THF）、2-甲基四(si)氫(qing)呋喃（2-MeTHF）、1，3-二(er)氧環戊烷(wan)（DOL）和(he)4-甲基-1，3-二(er)氧環戊烷(wan)（4-MeDOL）等。鏈狀(zhuang)醚(mi)(mi)主要包(bao)括二(er)甲氧甲烷(wan)（DMM）、1，2-二(er)甲氧乙烷(wan)（DME）、1，2-二(er)甲氧丙(bing)烷(wan)（DMP）和(he)二(er)甘醇二(er)甲醚(mi)(mi)（DG）等。冠醚(mi)(mi)和(he)穴(xue)醚(mi)(mi)能(neng)與(yu)鋰離子(zi)形成(cheng)包(bao)覆式整(zheng)合(he)物，較大地提(ti)(ti)高(gao)鋰鹽的(de)(de)(de)溶(rong)解(jie)度(du)，實現陰(yin)陽離子(zi)對的(de)(de)(de)有(you)效分(fen)離和(he)鋰離子(zi)與(yu)溶(rong)劑分(fen)子(zi)的(de)(de)(de)分(fen)離。這不僅能(neng)提(ti)(ti)高(gao)電(dian)(dian)解(jie)液的(de)(de)(de)電(dian)(dian)導率，而(er)且能(neng)降低在充電(dian)(dian)過程(cheng)中溶(rong)劑的(de)(de)(de)共嵌入和(he)分(fen)解(jie)的(de)(de)(de)可能(neng)性！，但冠醚(mi)(mi)化(hua)合(he)物價格昂貴(gui)且有(you)毒(du)使(shi)其應(ying)用受到限制。

4、新型有機溶劑

為了(le)改善鋰離(li)子(zi)(zi)電(dian)(dian)(dian)(dian)池的(de)(de)(de)綜合(he)性(xing)能，人們開(kai)始開(kai)發新型的(de)(de)(de)有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)，目(mu)前新型溶(rong)(rong)劑(ji)的(de)(de)(de)研究工(gong)作主要集中(zhong)在(zai)不燃(ran)(ran)(ran)(ran)和阻(zu)燃(ran)(ran)(ran)(ran)有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)兩個方面(mian)。通過(guo)在(zai)常(chang)用有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)分子(zi)(zi)中(zhong)，引進(jin)鹵素原(yuan)(yuan)(yuan)子(zi)(zi)，可(ke)(ke)以降(jiang)(jiang)低有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)的(de)(de)(de)可(ke)(ke)燃(ran)(ran)(ran)(ran)性(xing)，甚至使其完全(quan)不燃(ran)(ran)(ran)(ran)。用鹵素原(yuan)(yuan)(yuan)子(zi)(zi)取代PC分子(zi)(zi)中(zhong)甲基的(de)(de)(de)氫原(yuan)(yuan)(yuan)子(zi)(zi)，得到(dao)新化合(he)物如三氟代碳酸丙烯酯（C F-EC）J67，具有(you)(you)(you)(you)(you)(you)非常(chang)好(hao)的(de)(de)(de)物理和化學(xue)穩定(ding)性(xing)，而(er)且還(huan)具有(you)(you)(you)(you)(you)(you)較(jiao)高的(de)(de)(de)介電(dian)(dian)(dian)(dian)常(chang)數(shu)，不易燃(ran)(ran)(ran)(ran)燒(shao)(shao)(shao)，可(ke)(ke)作為不燃(ran)(ran)(ran)(ran)溶(rong)(rong)劑(ji)用于(yu)鋰離(li)子(zi)(zi)電(dian)(dian)(dian)(dian)池中(zhong)。阻(zu)燃(ran)(ran)(ran)(ran)溶(rong)(rong)劑(ji)不僅本身(shen)不會燃(ran)(ran)(ran)(ran)燒(shao)(shao)(shao)，而(er)且能夠通過(guo)氣相阻(zu)燃(ran)(ran)(ran)(ran)機(ji)(ji)理，也有(you)(you)(you)(you)(you)(you)可(ke)(ke)能同(tong)時(shi)通過(guo)凝(ning)聚相阻(zu)燃(ran)(ran)(ran)(ran)機(ji)(ji)理來阻(zu)止其它常(chang)規有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)的(de)(de)(de)燃(ran)(ran)(ran)(ran)燒(shao)(shao)(shao)。如三甲基磷酸酯（TMP）本身(shen)就是優(you)良的(de)(de)(de)阻(zu)燃(ran)(ran)(ran)(ran)劑(ji)，采(cai)用它作為鋰離(li)子(zi)(zi)電(dian)(dian)(dian)(dian)池有(you)(you)(you)(you)(you)(you)機(ji)(ji)溶(rong)(rong)劑(ji)無(wu)疑可(ke)(ke)顯著(zhu)改善電(dian)(dian)(dian)(dian)池的(de)(de)(de)安全(quan)性(xing)。TMP具有(you)(you)(you)(you)(you)(you)較(jiao)好(hao)的(de)(de)(de)氧化穩定(ding)性(xing)，但(dan)還(huan)原(yuan)(yuan)(yuan)穩定(ding)性(xing)卻很差，它在(zai)石墨(mo)電(dian)(dian)(dian)(dian)極上，在(zai)負電(dian)(dian)(dian)(dian)勢(shi)為1.2V時(shi)，TMP被無(wu)限制地大量還(huan)原(yuan)(yuan)(yuan)分解產生(sheng)CH4、C2H4等氣體產物，加(jia)入共溶(rong)(rong)劑(ji)EC、PC等可(ke)(ke)抑制其還(huan)原(yuan)(yuan)(yuan)分解，但(dan)隨(sui)著(zhu)共溶(rong)(rong)劑(ji)含量的(de)(de)(de)增加(jia)，電(dian)(dian)(dian)(dian)解液(ye)的(de)(de)(de)不燃(ran)(ran)(ran)(ran)性(xing)下降(jiang)(jiang)。