鋰電池充電的原理解析
鋰電池充電器的基本要求是特定的充電電流和充電電壓,從而保證電池安全充電。增加其它充電輔助功能是為了改善電池壽命,簡化充電器的操作,其中包括給過放電的電池使用涓流充電、電池電壓檢測、輸入電流限制、充電完成后關斷充電器、電(dian)(dian)(dian)池(chi)部分(fen)放(fang)電(dian)(dian)(dian)后自動(dong)啟動(dong)充電(dian)(dian)(dian)等(deng)。
鋰離子電池的充電過程可以分為四個階段:涓流充電(低壓預充)、恒流充電、恒壓充電以及充電終止。
鋰電池充電器的基本要求是特定的充電電流和充電電壓,從而保證電池安全充電。增加其它充電輔助功能是為了改善電池壽命,簡化充電器的操作,其中包括給過放電的電池使用涓流充電、電池電壓檢測、輸入電流限制、充電完成后關斷充電器、電池部分放電后自動啟動充電等。
鋰電池的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)方(fang)式是(shi)限壓(ya)恒(heng)流(liu)(liu),都是(shi)由IC芯片控制的(de),典型的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)方(fang)式是(shi):先(xian)檢測待充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)池的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya),如(ru)果電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)低于(yu)3V,要(yao)先(xian)進(jin)行(xing)預(yu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian),充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)為設定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)的(de)1/10,電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)升到3V后,進(jin)入標準充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)。標準充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)為:以設定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)進(jin)行(xing)恒(heng)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian),電(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)升到4.20V時,改為恒(heng)壓(ya)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian),保持充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)為 4.20V。此時,充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)逐漸下降,當電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)下降至設定(ding)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)的(de)1/10時,充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)結束。下圖為充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)曲線。
階段1:涓流充電——涓流充電用來先對完全放電的電池單元進行預充(恢復性充電)。在電池電壓低于3V左右時采用涓流充電,涓流充電電流是恒流充電電流的十分之一即0.1c(以恒定充電電流為1A舉例,則涓流充電電流為100mA),
階段2:恒流充電——當電池電壓上升到涓流充電閾值以上時,提高充電電流進行恒流充電。恒流充電的電流在0.2C至 1.0C之間。電池電壓隨著恒流充電過程逐步升高,一般單節電池設定的此電壓為3.0-4.2V.
階段(duan)(duan)3:恒壓充電(dian)(dian)(dian)(dian)—— 當電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)壓上(shang)升到4.2V時(shi),恒流(liu)充電(dian)(dian)(dian)(dian)結束,開始恒壓充電(dian)(dian)(dian)(dian)階段(duan)(duan)。電(dian)(dian)(dian)(dian)流(liu)根據電(dian)(dian)(dian)(dian)芯的(de)飽和(he)程度,隨著充電(dian)(dian)(dian)(dian)過程的(de)繼續充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)由最大值慢(man)慢(man)減(jian)少(shao),當減(jian)小到0.01C時(shi),認為充電(dian)(dian)(dian)(dian)終止。(C是(shi)以電(dian)(dian)(dian)(dian)池標稱容(rong)(rong)量(liang)對照電(dian)(dian)(dian)(dian)流(liu)的(de)一種表(biao)示方法,如電(dian)(dian)(dian)(dian)池是(shi)1000mAh的(de)容(rong)(rong)量(liang),1C就(jiu)是(shi)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)1000mA。)