如果大家注意的話會發現我們見到的和使用的鋰電池上面標的單顆電芯電壓(ya)都是(shi)3.7V，為什么鋰電池標的電壓(ya)是(shi)3.7V，相信很多(duo)朋友對這個問題的答(da)案感興趣，下面就簡單和大家解釋一下吧。

一、鋰(li)電池的(de)放電平臺解(jie)釋

先說一下鋰電池的(de)(de)(de)放電(dian)(dian)平(ping)(ping)臺，就(jiu)是(shi)指充滿電(dian)(dian)的(de)(de)(de)鋰電(dian)(dian)池(chi)在放電(dian)(dian)時(shi)，電(dian)(dian)池(chi)的(de)(de)(de)電(dian)(dian)壓變(bian)化狀態(tai)。電(dian)(dian)池(chi)恒(heng)流放電(dian)(dian)，電(dian)(dian)池(chi)電(dian)(dian)壓要經(jing)歷三(san)(san)個過(guo)程(cheng)，即下(xia)降、穩(wen)定(ding)(ding)、再下(xia)降，在這三(san)(san)個過(guo)程(cheng)中(zhong)，穩(wen)定(ding)(ding)期是(shi)最長(chang)的(de)(de)(de)。穩(wen)定(ding)(ding)時(shi)間越長(chang)，說明電(dian)(dian)池(chi)的(de)(de)(de)放電(dian)(dian)平(ping)(ping)臺越高。放電(dian)(dian)平(ping)(ping)臺的(de)(de)(de)高低(di)，與電(dian)(dian)池(chi)制(zhi)(zhi)造工(gong)藝息息相關。就(jiu)是(shi)因為各個鋰電(dian)(dian)池(chi)廠(chang)家的(de)(de)(de)市場(chang)定(ding)(ding)位不(bu)一樣，技(ji)術(shu)工(gong)藝手段不(bu)同，其控制(zhi)(zhi)的(de)(de)(de)放電(dian)(dian)平(ping)(ping)臺就(jiu)不(bu)一樣，質量也就(jiu)有(you)很大差別。

一般地的鋰電(dian)(dian)(dian)(dian)池滿電(dian)(dian)(dian)(dian)壓4.2V，當(dang)一顆2200mAh鋰電(dian)(dian)(dian)(dian)池用1C的電(dian)(dian)(dian)(dian)流(liu)放(fang)電(dian)(dian)(dian)(dian)放(fang)到3.7V，放(fang)了60分鐘，那么(me)我(wo)們就說電(dian)(dian)(dian)(dian)池的使用容(rong)量是2200mAh，在這段時間(jian)里根據充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)池特(te)性，做出一個圖如下，可以更好(hao)理解電(dian)(dian)(dian)(dian)池容(rong)量和電(dian)(dian)(dian)(dian)壓電(dian)(dian)(dian)(dian)流(liu)時間(jian)與(yu)放(fang)電(dian)(dian)(dian)(dian)平臺(tai)關系：

鋰電(dian)池電(dian)池容量與放(fang)電(dian)平臺理解(jie)示意圖

容量（C）=放電電流×電池放電平臺時間

對于一顆容(rong)量為2200mAh的鋰電池來(lai)說，1C放電到3.7V用時(shi)1小時(shi)，

容(rong)量(liang)（C）=2200mA×1小時=2200mAh

那么問(wen)題就(jiu)來了(le)，對于好一(yi)點的(de)鋰電(dian)(dian)(dian)池(chi)(chi)，一(yi)般在(zai)(zai)(zai)我(wo)們做產品測試時(shi)會在(zai)(zai)(zai)3.7V以(yi)(yi)后(hou)電(dian)(dian)(dian)壓下降的(de)很快，那么在(zai)(zai)(zai)短時(shi)間內放的(de)電(dian)(dian)(dian)量就(jiu)很少。相反(fan)不好的(de)電(dian)(dian)(dian)池(chi)(chi)在(zai)(zai)(zai)4.2V到(dao)3.7V放電(dian)(dian)(dian)的(de)時(shi)候，電(dian)(dian)(dian)壓下降的(de)很快，而(er)在(zai)(zai)(zai)3.7V以(yi)(yi)后(hou)電(dian)(dian)(dian)壓又下降的(de)有(you)很慢，這種(zhong)電(dian)(dian)(dian)池(chi)(chi)是性(xing)能(neng)不好的(de)一(yi)般容量也非常低。那么好的(de)鋰電(dian)(dian)(dian)池(chi)(chi)的(de)放電(dian)(dian)(dian)平臺就(jiu)是3.7V。

就一般而言(yan)，在(zai)恒壓條(tiao)件下，充到電(dian)壓為4.2V，電(dian)流小于0.01C時(shi)(shi)停充電(dian)，然(ran)后擱置(zhi)10分(fen)鐘，在(zai)任何倍率(lv)的(de)放電(dian)電(dian)流下，放電(dian)至(zhi)3.7V時(shi)(shi)，電(dian)池放電(dian)所經歷的(de)一個時(shi)(shi)間(jian)長度，是衡量電(dian)池好壞的(de)重要指標。不(bu)(bu)過，不(bu)(bu)要一味(wei)地(di)追求高(gao)平(ping)(ping)臺(tai)，有時(shi)(shi)候平(ping)(ping)臺(tai)電(dian)壓高(gao)，容(rong)量卻下降了，因為，不(bu)(bu)同(tong)倍率(lv)條(tiao)件下，平(ping)(ping)臺(tai)電(dian)壓是不(bu)(bu)同(tong)的(de)，因此，平(ping)(ping)臺(tai)的(de)問題應(ying)從多方考慮。既要容(rong)量高(gao)，又要在(zai)指定電(dian)壓持續(xu)時(shi)(shi)間(jian)長，才算真正的(de)好電(dian)池。

什(shen)么又是放電率的呢？

放電率(lv)F：［1/時(shi)(shi)］，意思是“N小時(shi)(shi)充（放）電率(lv)，常常只(zhi)說(shuo)”數(shu)“，而(er)不說(shuo)單位;F也稱(cheng)做(zuo)”N小時(shi)(shi)充（放）電率(lv)“，F=1/（N小時(shi)(shi)），

一般可(ke)以這(zhe)樣計算：I=0.1X［1/（N小時）］XC

舉例，電(dian)池(chi)容(rong)量(liang)時(shi)2200mAh，以0.1C的電(dian)流充電(dian)，相當于(yu)明確：對電(dian)池(chi)的充電(dian)電(dian)流I=0.1［1/時(shi)］X2200［毫安時(shi)］=220［毫安］

借助上面的(de)(de)(de)(de)鋰(li)電(dian)(dian)池(chi)(chi)(chi)(chi)電(dian)(dian)池(chi)(chi)(chi)(chi)容(rong)量(liang)與放電(dian)(dian)平(ping)臺(tai)理(li)解(jie)示意圖，能比較(jiao)好的(de)(de)(de)(de)理(li)解(jie)充電(dian)(dian)電(dian)(dian)池(chi)(chi)(chi)(chi)容(rong)量(liang)和(he)電(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)(de)(de)放電(dian)(dian)平(ping)臺(tai)的(de)(de)(de)(de)道理(li)，也可以說是衡(heng)量(liang)電(dian)(dian)池(chi)(chi)(chi)(chi)高(gao)功率的(de)(de)(de)(de)工作(zuo)時(shi)間(jian)(jian)(jian)，同樣兩(liang)個(ge)(ge)電(dian)(dian)池(chi)(chi)(chi)(chi)容(rong)量(liang)是相同的(de)(de)(de)(de)，充滿電(dian)(dian)后假(jia)設(she)同時(shi)從4.2V放到3.7V，但是一(yi)個(ge)(ge)時(shi)間(jian)(jian)(jian)長(chang)(chang)，一(yi)個(ge)(ge)時(shi)間(jian)(jian)(jian)短，就是時(shi)間(jian)(jian)(jian)長(chang)(chang)的(de)(de)(de)(de)電(dian)(dian)池(chi)(chi)(chi)(chi)平(ping)臺(tai)高(gao)，就是高(gao)電(dian)(dian)壓的(de)(de)(de)(de)時(shi)間(jian)(jian)(jian)工作(zuo)時(shi)間(jian)(jian)(jian)長(chang)(chang)，比如這兩(liang)個(ge)(ge)電(dian)(dian)池(chi)(chi)(chi)(chi)用在手(shou)機上，待機時(shi)間(jian)(jian)(jian)是相同的(de)(de)(de)(de)，但兩(liang)個(ge)(ge)手(shou)機一(yi)起打(da)電(dian)(dian)話(hua)，平(ping)臺(tai)時(shi)間(jian)(jian)(jian)長(chang)(chang)的(de)(de)(de)(de)電(dian)(dian)池(chi)(chi)(chi)(chi)通知時(shi)間(jian)(jian)(jian)會(hui)長(chang)(chang)，平(ping)臺(tai)時(shi)間(jian)(jian)(jian)短的(de)(de)(de)(de)電(dian)(dian)池(chi)(chi)(chi)(chi)通話(hua)時(shi)間(jian)(jian)(jian)會(hui)短

二、對(dui)于這(zhe)個(ge)圖，另(ling)一個(ge)含義，對(dui)理解鋰電池的(de)電量(liang)管(guan)理監測也很有意義。

比如，目前，對充電電池進(jin)行電量監控方(fang)法，一般(ban)有兩種。

測(ce)(ce)(ce)(ce)量電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)方(fang)法。當(dang)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器在充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)檢測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)達到(dao)規定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)值時(shi)就(jiu)(jiu)認(ren)為充(chong)滿(man)。如鋰(li)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)充(chong)到(dao)4.2V時(shi)就(jiu)(jiu)認(ren)為充(chong)滿(man)。檢測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)表精度要達到(dao)正負1%的精度。因鋰(li)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)過充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)要損壞。如果(guo)想監視電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充(chong)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的話(hua)，書上有很(hen)成熟的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路可以參(can)考，如果(guo)只是測(ce)(ce)(ce)(ce)量一(yi)(yi)下的話(hua)那就(jiu)(jiu)好辦了(le)，根據容(rong)量計算一(yi)(yi)下負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻，用標準(zhun)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，這時(shi)再檢測(ce)(ce)(ce)(ce)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，只要能達到(dao)或接(jie)近標稱的放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)時(shi)間就(jiu)(jiu)行(xing)。

測量電(dian)池(chi)電(dian)壓這種方法，有很(hen)多(duo)不(bu)足(zu)例如對于(yu)不(bu)同(tong)廠商生產的(de)電(dian)池(chi)，其開路電(dian)壓與容(rong)量之間(jian)的(de)關系各(ge)不(bu)相(xiang)同(tong)等。優點是設計成本比較(jiao)低。

還有一(yi)個常(chang)用(yong)的(de)(de)監測剩(sheng)余電(dian)(dian)(dian)(dian)(dian)量(liang)的(de)(de)方(fang)(fang)(fang)法是(shi)，在一(yi)些要求比(bi)較(jiao)(jiao)精確(que)電(dian)(dian)(dian)(dian)(dian)池容(rong)(rong)量(liang)的(de)(de)地方(fang)(fang)(fang)，了解電(dian)(dian)(dian)(dian)(dian)池剩(sheng)余容(rong)(rong)量(liang)用(yong)估算電(dian)(dian)(dian)(dian)(dian)池使(shi)用(yong)時間(jian)，通過測量(liang)流(liu)(liu)(liu)入/流(liu)(liu)(liu)出電(dian)(dian)(dian)(dian)(dian)池的(de)(de)凈電(dian)(dian)(dian)(dian)(dian)荷(he)來(lai)估算電(dian)(dian)(dian)(dian)(dian)池剩(sheng)余容(rong)(rong)量(liang)。對流(liu)(liu)(liu)入/流(liu)(liu)(liu)出電(dian)(dian)(dian)(dian)(dian)池的(de)(de)總電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)進行積分，也就是(shi)求圖中曲線(xian)下的(de)(de)面積，得到(dao)的(de)(de)凈電(dian)(dian)(dian)(dian)(dian)荷(he)數(shu)即為剩(sheng)余容(rong)(rong)量(liang)。這(zhe)就電(dian)(dian)(dian)(dian)(dian)池容(rong)(rong)量(liang)計算的(de)(de)方(fang)(fang)(fang)法是(shi)目前認為是(shi)比(bi)較(jiao)(jiao)精確(que)的(de)(de)計算電(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)量(liang)的(de)(de)方(fang)(fang)(fang)法。當然設計成本也是(shi)比(bi)較(jiao)(jiao)高(gao)的(de)(de)。

三、從(cong)充(chong)放電數據(ju)監測(ce)來說

鋰(li)電充滿電，大概會是(shi)4.2V或(huo)者4.3V.

鋰電(dian)(dian)放完電(dian)(dian)，大概會是3.0V。

鋰電放(fang)電圖，是呈拋物線的(de)，4.3V降到3.7V和3.7V降到3.0V，都是變化很快的(de)。

惟有3.7V左右的放電時間(jian)是(shi)最長的，幾乎占到了3/4的時間(jian)。

所以才(cai)會標3.7V的。