鋰離子電池用不了的原因
鋰離子電池用不了是指由某些特定的本質原因引起的電池性能衰減或使用性能異常,它可能發生在生產、運輸、使用中的任何一個環節,不僅會影響電池的性能,甚至會引發起火、爆炸等安全問題。鋰離子電池用不了根據影響類型的不同,可以分為性能失效和安全性失效。

鋰離子(zi)電池容(rong)量衰減用不了
一般在進行標(biao)(biao)準循(xun)環(huan)壽命測試時,在循(xun)環(huan)次數達到500次后,鋰離子(zi)(zi)電池(chi)(chi)容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)不(bu)應低(di)于(yu)初(chu)始(shi)值的90%,達到1000次后,不(bu)應低(di)于(yu)初(chu)始(shi)值的80%,如容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)不(bu)符合該標(biao)(biao)準出現(xian)衰(shuai)減(jian)(jian)(jian)(jian)(jian)過(guo)度的現(xian)象(xiang),則屬于(yu)容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)衰(shuai)減(jian)(jian)(jian)(jian)(jian)失效。鋰離子(zi)(zi)電池(chi)(chi)的容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)衰(shuai)減(jian)(jian)(jian)(jian)(jian)失效分為可(ke)逆(ni)容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)衰(shuai)減(jian)(jian)(jian)(jian)(jian)和不(bu)可(ke)逆(ni)容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)衰(shuai)減(jian)(jian)(jian)(jian)(jian)。其(qi)中可(ke)逆(ni)衰(shuai)減(jian)(jian)(jian)(jian)(jian)能夠通過(guo)調整電池(chi)(chi)的充放電制度及改(gai)善(shan)電池(chi)(chi)的使(shi)用環(huan)境(jing)等方法(fa)恢復損(sun)失的容(rong)(rong)(rong)量(liang)(liang)(liang)(liang),不(bu)可(ke)逆(ni)衰(shuai)減(jian)(jian)(jian)(jian)(jian)因為是電池(chi)(chi)內(nei)部發(fa)生了(le)不(bu)可(ke)逆(ni)的變化產生了(le)無法(fa)恢復的容(rong)(rong)(rong)量(liang)(liang)(liang)(liang)損(sun)失,因此無法(fa)挽救(jiu)。
電池(chi)容量衰(shuai)減(jian)的(de)主要原(yuan)因(yin)在于材(cai)料(liao)失(shi)效,也和電池(chi)的(de)制造(zao)工藝、使用環境等客觀因(yin)素(su)有(you)(you)不可分割的(de)聯系。從材(cai)料(liao)角度來(lai)說,造(zao)成容量衰(shuai)減(jian)失(shi)效的(de)成因(yin)有(you)(you)正極材(cai)料(liao)失(shi)效、負極表面SEI過渡生產(chan)、電解液(ye)失(shi)效、集流體失(shi)效等等。
鋰(li)離子(zi)電池內短路用(yong)不了
鋰離子電(dian)池內短(duan)路(lu)往(wang)往(wang)會引起自放(fang)電(dian),容量衰(shuai)減,局(ju)(ju)部(bu)熱失(shi)(shi)控以及引起安全事故。在電(dian)池內部(bu)發(fa)生(sheng)短(duan)路(lu)期間,兩種電(dian)極材料以電(dian)子方式在內部(bu)互(hu)連,導致局(ju)(ju)部(bu)高電(dian)流密(mi)度。鋰離子電(dian)池中發(fa)生(sheng)內部(bu)短(duan)路(lu)可能是鋰枝晶的形(xing)成(cheng)或壓縮沖擊等情(qing)況引起的。長時間的內部(bu)短(duan)路(lu)會導致自放(fang)電(dian)及局(ju)(ju)部(bu)溫(wen)度上升(sheng),局(ju)(ju)部(bu)溫(wen)度上升(sheng)產生(sheng)的影響非常顯著,因為如果溫(wen)度超出某一閾值,電(dian)解質可能通(tong)過放(fang)熱反應(ying)開始分(fen)解,從(cong)而引起熱失(shi)(shi)控,具有潛在的健康和安全隱患。
鋰離子(zi)電池內阻增大用不了
鋰離(li)子(zi)電池內(nei)阻與電池內(nei)部電子(zi)傳(chuan)輸和(he)離(li)子(zi)傳(chuan)輸過程有(you)關(guan),主(zhu)要分為歐(ou)姆電阻和(he)極(ji)化(hua)(hua)(hua)內(nei)阻,極(ji)化(hua)(hua)(hua)內(nei)阻主(zhu)要由(you)電化(hua)(hua)(hua)學極(ji)化(hua)(hua)(hua)引發,又(you)分為電化(hua)(hua)(hua)學極(ji)化(hua)(hua)(hua)和(he)濃(nong)差極(ji)化(hua)(hua)(hua)。當電池內(nei)阻增(zeng)大(da)時,伴隨而生的還(huan)有(you)能量(liang)密度下降、電壓功(gong)率下降、電池產(chan)熱等失效問題。影響(xiang)其產(chan)生的主(zhu)要因(yin)素(su)有(you)電池關(guan)鍵材料(liao)與電池使用環(huan)境(jing),但(dan)關(guan)鍵材料(liao)產(chan)生異常(chang)是內(nei)阻增(zeng)大(da)的根本影響(xiang)因(yin)素(su)。
鋰離子電池熱(re)失控用(yong)不了
“熱(re)(re)(re)失控(kong)(kong)(kong)(kong)”是一個(ge)能(neng)量正反(fan)饋循環過程:升(sheng)高的(de)(de)溫(wen)(wen)度(du)(du)會導(dao)致(zhi)系(xi)(xi)統(tong)(tong)變(bian)熱(re)(re)(re),系(xi)(xi)統(tong)(tong)變(bian)熱(re)(re)(re)升(sheng)高溫(wen)(wen)度(du)(du),這又反(fan)過來(lai)又讓系(xi)(xi)統(tong)(tong)變(bian)得更(geng)熱(re)(re)(re)。鋰電(dian)(dian)(dian)池熱(re)(re)(re)失控(kong)(kong)(kong)(kong)則(ze)是指電(dian)(dian)(dian)池內部(bu)局部(bu)或整體的(de)(de)溫(wen)(wen)度(du)(du)急速上升(sheng)熱(re)(re)(re)量不能(neng)及時散去,大(da)量積聚(ju)在內部(bu),并誘發(fa)(fa)進一步的(de)(de)副(fu)反(fan)應。參與“熱(re)(re)(re)失控(kong)(kong)(kong)(kong)”反(fan)應的(de)(de)是鋰電(dian)(dian)(dian)池中的(de)(de)氧化(hua)鈷化(hua)學物。加(jia)熱(re)(re)(re)這種化(hua)學物達到(dao)一定溫(wen)(wen)度(du)(du),它就開始自(zi)發(fa)(fa)熱(re)(re)(re),然后發(fa)(fa)展成起火和爆炸。在某些情(qing)況(kuang)下(xia)(xia),這種有(you)機電(dian)(dian)(dian)解液釋放壓力(li)會導(dao)致(zhi)電(dian)(dian)(dian)池破裂。如(ru)果暴露在高溫(wen)(wen)環境下(xia)(xia),或者是遇到(dao)火花,它也有(you)可能(neng)會燃燒。為(wei)了防(fang)止熱(re)(re)(re)失控(kong)(kong)(kong)(kong)現(xian)象的(de)(de)發(fa)(fa)生,一般會采用PTC、安全閥、導(dao)熱(re)(re)(re)膜(mo)等(deng)措施,但更(geng)重要(yao)的(de)(de)是完善電(dian)(dian)(dian)池在設計、制(zhi)造(zao)的(de)(de)技術,及使用的(de)(de)方(fang)法(fa)。
鋰離子(zi)電池(chi)產(chan)氣用不了
鋰(li)離子(zi)電池(chi)產氣(qi)(qi)有兩種,分別是正常(chang)(chang)產氣(qi)(qi)和異常(chang)(chang)產氣(qi)(qi),在(zai)電池(chi)化(hua)成(cheng)工藝過程中消(xiao)耗(hao)電解(jie)液形成(cheng)穩定SEI膜(mo)所(suo)發生(sheng)的(de)(de)產氣(qi)(qi)現象為正常(chang)(chang)產氣(qi)(qi),過渡(du)消(xiao)耗(hao)電解(jie)液釋放氣(qi)(qi)體或(huo)正極(ji)材料釋氧等現象屬于異常(chang)(chang)產氣(qi)(qi)。在(zai)鋰(li)電池(chi)組(zu)裝完(wan)成(cheng)后(hou)(hou),預化(hua)成(cheng)過程中會產生(sheng)少量氣(qi)(qi)體,這些氣(qi)(qi)體是不可(ke)避免的(de)(de),也是所(suo)謂的(de)(de)電芯不可(ke)逆(ni)容量損失來源。在(zai)首(shou)次充(chong)放電過程中,電子(zi)由外電路到達負極(ji)后(hou)(hou)會與負極(ji)表面的(de)(de)電解(jie)液發生(sheng)氧化(hua)還原反應,生(sheng)成(cheng)氣(qi)(qi)體。
鋰(li)離子電池析鋰(li)用不了(le)
鋰(li)(li)離(li)子(zi)電(dian)(dian)池在充(chong)(chong)電(dian)(dian)過程中,鋰(li)(li)離(li)子(zi)會從(cong)正極(ji)(ji)(ji)(ji)脫嵌(qian)并嵌(qian)入(ru)負(fu)(fu)(fu)極(ji)(ji)(ji)(ji),但當發生異常情況造成從(cong)正極(ji)(ji)(ji)(ji)脫嵌(qian)的鋰(li)(li)離(li)子(zi)無(wu)法嵌(qian)入(ru)負(fu)(fu)(fu)極(ji)(ji)(ji)(ji)的話,鋰(li)(li)離(li)子(zi)就(jiu)只能析出在負(fu)(fu)(fu)極(ji)(ji)(ji)(ji)表面(mian),形成一層灰色(se)的物(wu)質,這就(jiu)是(shi)析鋰(li)(li)。析鋰(li)(li)的原因有(you)很多種,包括(kuo)負(fu)(fu)(fu)極(ji)(ji)(ji)(ji)余(yu)量不夠、正負(fu)(fu)(fu)極(ji)(ji)(ji)(ji)涂(tu)面(mian)不均勻、低溫(wen)環境(jing)充(chong)(chong)電(dian)(dian)、大(da)倍率(lv)充(chong)(chong)電(dian)(dian)等等。目前主要是(shi)通過加(jia)入(ru)電(dian)(dian)解液添加(jia)劑(ji)、人造SEI、高鹽度電(dian)(dian)解液、結構化(hua)(hua)負(fu)(fu)(fu)極(ji)(ji)(ji)(ji)、優(you)化(hua)(hua)電(dian)(dian)池結構來抑制析鋰(li)(li)失效的產生。
