鋰電池容量降低減少怎么回事?
鋰電池在使(shi)用了一定的(de)時間后,電池(chi)的(de)能持(chi)續使(shi)用是(shi)時間變短(duan)了,其實這個是(shi)鋰(li)電池(chi)的(de)容量損(sun)失造成的(de),那么(me)使(shi)鋰(li)電池(chi)容量損(sun)失的(de)原因(yin)是(shi)什么(me)呢?
可能的原因:
(1)沉積(ji)的(de)鋰(li)包覆在負極表面(mian),阻塞了鋰(li)的(de)嵌(qian)入,可循(xun)環(huan)鋰(li)量(liang)減(jian)少,導致放(fang)電效率降低(di)和容(rong)量(liang)損失。
(2)金屬鋰通常(chang)形(xing)成于負極與隔膜之間(jian),可能(neng)阻(zu)塞隔膜的孔(kong)隙增大(da)(da)電池內(nei)阻(zu)。快速充電,電流密度(du)過大(da)(da),負極嚴重極化(hua),鋰的沉(chen)積(ji)會更明(ming)顯。
(3)電化學惰性物質的產生(sheng),破壞了電極間的容(rong)量平衡,導(dao)致容(rong)量損(sun)失(shi),其(qi)容(rong)量損(sun)失(shi)是不可逆的。
(4)自放(fang)(fang)電(dian)(dian)(dian)。自放(fang)(fang)電(dian)(dian)(dian)是(shi)指(zhi)電(dian)(dian)(dian)池在(zai)未使用狀態下,電(dian)(dian)(dian)容(rong)(rong)量(liang)(liang)(liang)自然損(sun)失(shi)(shi)(shi)的現象。鋰離子電(dian)(dian)(dian)池自放(fang)(fang)電(dian)(dian)(dian)導致容(rong)(rong)量(liang)(liang)(liang)損(sun)失(shi)(shi)(shi)分兩種情(qing)況:一是(shi)可逆容(rong)(rong)量(liang)(liang)(liang)損(sun)失(shi)(shi)(shi);二是(shi)不可逆容(rong)(rong)量(liang)(liang)(liang)的損(sun)失(shi)(shi)(shi)。可逆容(rong)(rong)量(liang)(liang)(liang)損(sun)失(shi)(shi)(shi)是(shi)指(zhi)損(sun)失(shi)(shi)(shi)的容(rong)(rong)量(liang)(liang)(liang)能在(zai)充電(dian)(dian)(dian)時恢(hui)復,而不可逆容(rong)(rong)量(liang)(liang)(liang)損(sun)失(shi)(shi)(shi)則相(xiang)反,正極(ji)與溶劑會發(fa)生微電(dian)(dian)(dian)池作用產生自放(fang)(fang)電(dian)(dian)(dian)造成不可逆容(rong)(rong)量(liang)(liang)(liang)損(sun)失(shi)(shi)(shi)。
(5)電(dian)極(ji)不穩(wen)定性(xing).。正極(ji)活性(xing)物質在充(chong)電(dian)狀態下(xia)會(hui)氧化電(dian)解(jie)質分解(jie)而造成容量損失。另外,影(ying)響正極(ji)材料溶解(jie)的(de)因素還有(you)正極(ji)活性(xing)物質的(de)結構缺陷,充(chong)電(dian)電(dian)勢(shi)過高以及正極(ji)材料中炭黑的(de)含(han)量。其中電(dian)極(ji)在充(chong)放(fang)電(dian)循環過程中結構的(de)變化是最重要的(de)因素。





