磷酸鐵鋰電池真的安全嗎
現在,人們購買新能源汽車客觀上要在磷酸鐵鋰電池和(he)三元鋰電池兩種技術之間進行二選一的(de)(de)選擇,業內人(ren)士告訴我們(men):重(zhong)(zhong)視續航能力和(he)車輛輕型(xing)化的(de)(de)選三元系(xi),重(zhong)(zhong)視安(an)全性的(de)(de)選磷(lin)酸鐵鋰系(xi)。對此,消費者迫切希望業內人(ren)士能從技術角度切實(shi)地給出答(da)案:磷(lin)酸鐵鋰電池安(an)全嗎?
這一問題要(yao)從(cong)材料/結構穩(wen)定性(xing)(xing)、生(sheng)產工藝、充(chong)放電特性(xing)(xing)三個方(fang)面來回答。
磷酸鐵(tie)鋰(li)是目前最安全的鋰(li)離子(zi)電池正(zheng)極(ji)材(cai)料,不含(han)任何對人體(ti)有(you)害的重金屬元素,其橄欖石結(jie)構中氧氣(qi)很難析出,提高了材(cai)料的穩定性。
磷酸鐵鋰電池生產流程與其他鋰電池品種大體相(xiang)同,其核心工序(xu)有:配(pei)料、涂布、輥壓、制片、卷繞。在配(pei)料環節,磷酸鐵(tie)鋰材料導電性能相(xiang)對較差,所以,顆粒一(yi)般做得更小(xiao)一(yi)些(xie),這樣做的客觀效(xiao)果(guo)是:內部排(pai)列更為均勻,促(cu)使其形(xing)成了(le)平衡(heng)的電壓平臺,工作時(shi)能夠(gou)保(bao)持電池的狀態穩定。
充(chong)放電(dian)(dian)是(shi)鋰(li)(li)電(dian)(dian)池兩種基本的(de)工作(zuo)狀態。當磷酸(suan)鐵(tie)鋰(li)(li)電(dian)(dian)池充(chong)放電(dian)(dian)時(shi),由于鐵(tie)離子氧(yang)化(hua)(hua)(hua)能(neng)力(li)不強,不會放出氧(yang)氣(qi),自然也(ye)就難以與電(dian)(dian)解(jie)質發生氧(yang)化(hua)(hua)(hua)還(huan)原反(fan)應(ying),這(zhe)使得磷酸(suan)鐵(tie)鋰(li)(li)電(dian)(dian)池充(chong)放電(dian)(dian)過程處在(zai)一個安全的(de)環境中(zhong)。不但(dan)如此,磷酸(suan)鐵(tie)鋰(li)(li)電(dian)(dian)池在(zai)大倍率放電(dian)(dian),甚至過充(chong)放電(dian)(dian)過程中(zhong),也(ye)難以發生劇烈的(de)氧(yang)化(hua)(hua)(hua)還(huan)原反(fan)應(ying)。同時(shi),鋰(li)(li)在(zai)脫嵌后,晶(jing)(jing)格變化(hua)(hua)(hua)使晶(jing)(jing)胞(晶(jing)(jing)體(ti)的(de)最(zui)小(xiao)構(gou)成單位)最(zui)終體(ti)積(ji)會縮小(xiao),這(zhe)正好抵銷了(le)碳負極在(zai)反(fan)應(ying)中(zhong)增加的(de)體(ti)積(ji),所以,在(zai)充(chong)放電(dian)(dian)中(zhong)磷酸(suan)鐵(tie)鋰(li)(li)電(dian)(dian)池能(neng)夠保持物理結構(gou)的(de)穩定,消除(chu)了(le)體(ti)積(ji)增大而產生電(dian)(dian)池爆裂現象的(de)隱患。
上面(mian)說(shuo)到的(de)(de)電(dian)(dian)(dian)池(chi)(chi)安全性是為了方(fang)便(bian)起見而采(cai)用(yong)單體(ti)為例予以(yi)說(shuo)明(ming),在投放使(shi)用(yong)時(shi),磷(lin)(lin)(lin)酸(suan)鐵鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)需要提供(gong)適用(yong)于用(yong)電(dian)(dian)(dian)器具(ju)的(de)(de)額定電(dian)(dian)(dian)壓與容量,這(zhe)時(shi)就(jiu)需要進行磷(lin)(lin)(lin)酸(suan)鐵鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)配組(zu)(zu)工(gong)作(zuo),即,把(ba)單體(ti)磷(lin)(lin)(lin)酸(suan)鐵鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)通(tong)過串(chuan)聯(lian)/并聯(lian)/串(chuan)并聯(lian)方(fang)式裝備成(cheng)可(ke)供(gong)實用(yong)的(de)(de)鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)。這(zhe)種配組(zu)(zu)工(gong)作(zuo)最需要注(zhu)意的(de)(de)是各(ge)個單體(ti)電(dian)(dian)(dian)池(chi)(chi)的(de)(de)一致性。通(tong)常,它(ta)還帶有均衡管理系統,通(tong)過關鍵參數控(kong)制保證鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)使(shi)用(yong)的(de)(de)安全性,這(zhe)一點(dian)則(ze)是各(ge)類鋰(li)(li)電(dian)(dian)(dian)池(chi)(chi)組(zu)(zu)的(de)(de)共(gong)同特點(dian)。





