手機充電器,用完電再充?
充(chong)電(dian)放電(dian)實際上是鋰離子的運動
“首先要明白一(yi)點(dian),2000年以后,市(shi)面(mian)(mian)上的手(shou)機電池出現(xian)了(le)一(yi)次改朝換(huan)代,那就是(shi)由(you)鋰離(li)子電池取代了(le)鎳(nie)氫電池,而現(xian)在市(shi)面(mian)(mian)上銷(xiao)售(shou)的手(shou)機百分之百都(dou)是(shi)鋰離(li)子電池。”南(nan)京(jing)理工大學材料(liao)科學與工程學院教授(shou)、博士生(sheng)導師杜宇(yu)雷說(shuo)。
關于手機電(dian)池的(de)(de)種(zhong)種(zhong)說法,必是建立(li)在鋰離子電(dian)池的(de)(de)性能之上的(de)(de)。那么我們不妨先了(le)解一下(xia)鋰離子電(dian)池的(de)(de)內部構造。
“電(dian)池(chi)(chi)的(de)基(ji)本構造包括(kuo)正極(ji)、負極(ji)與電(dian)解質(zhi)三項(xiang)要(yao)素(su)。作為電(dian)池(chi)(chi)的(de)一(yi)種,鋰離(li)子(zi)電(dian)池(chi)(chi)同(tong)樣具有這三個要(yao)素(su)。”杜教授說,鋰離(li)子(zi)電(dian)池(chi)(chi)的(de)正極(ji)是鈷(gu)酸鋰(或錳酸鋰等),負極(ji)是石墨,正負極(ji)中間有一(yi)層隔膜。
從化學反(fan)應來說(shuo),所謂(wei)充電的(de)過程(cheng),就是(shi)鋰(li)離子從正極的(de)鈷酸鋰(li)晶(jing)體結(jie)構中跑出來,經過電解質(zhi),嵌入負極石墨中。而(er)放電過程(cheng)則剛好相反(fan),鋰(li)離子從石墨中脫嵌回到鈷酸鋰(li)中。“這是(shi)一個可逆的(de)化學反(fan)應。”
不(bu)過(guo)雖然這(zhe)種(zhong)反(fan)應是(shi)可逆的(de)(de),但(dan)是(shi)電(dian)池使用(yong)過(guo)程(cheng)中,正、負極材料、電(dian)解液和隔膜(mo)等的(de)(de)變化都會引起鋰離(li)子電(dian)池的(de)(de)性能退化,所以從大(da)的(de)(de)趨勢來(lai)看,電(dian)池的(de)(de)電(dian)量(liang)總(zong)是(shi)在不(bu)斷減(jian)少。對于(yu)手機鋰離(li)子電(dian)池的(de)(de)循環(huan)壽命,我們國家(jia)的(de)(de)“國標”要求(qiu):50次(ci)充(chong)放電(dian)循環(huan)后(hou),電(dian)池容量(liang)降(jiang)低(di)小于(yu)5%,400次(ci)充(chong)放電(dian)循環(huan)后(hou),電(dian)池容量(liang)降(jiang)低(di)小于(yu)20%。這(zhe)里(li)的(de)(de)一(yi)個充(chong)放電(dian)循環(huan)是(shi)指(zhi)將電(dian)池充(chong)至標準電(dian)量(liang)再用(yong)光的(de)(de)過(guo)程(cheng)。
從以上分析,我們會知道(dao)鋰離子電(dian)(dian)(dian)池(chi)在(zai)使(shi)用(yong)中其容(rong)量總是(shi)(shi)在(zai)不(bu)斷降低的。杜教授說,現在(zai)的智能手機,大多2-3天充一(yi)次電(dian)(dian)(dian),也就是(shi)(shi)一(yi)年約(yue)有150次充放電(dian)(dian)(dian)循環.。實際使(shi)用(yong)中,由于受(shou)到使(shi)用(yong)環境、充放電(dian)(dian)(dian)過程(cheng)的差異等因素的影響,電(dian)(dian)(dian)池(chi)容(rong)量的損(sun)失可能比“國標(biao)”測試條件下(xia)要(yao)大,這(zhe)就是(shi)(shi)大多數人感覺電(dian)(dian)(dian)池(chi)在(zai)使(shi)用(yong)1-2年后明顯(xian)不(bu)經(jing)用(yong)了的原因。
1點提醒
不要混用(yong)充電器,慎用(yong)萬能充
杜(du)教授提醒,鋰離子電(dian)池是(shi)有標(biao)準的充電(dian)程(cheng)序的,手機(ji)標(biao)配的充電(dian)器就是(shi)按照(zhao)這個程(cheng)序充電(dian)的。
像有一些萬能充電(dian)器(qi),它(ta)的(de)設計就(jiu)是(shi)(shi)恒(heng)流(liu)充完(wan)恒(heng)壓充,但(dan)是(shi)(shi)電(dian)壓沒有截(jie)止,所(suo)以后面一直以小電(dian)流(liu)充,這樣看上(shang)去電(dian)量(liang)充得(de)滿很耐用,其(qi)實損(sun)害(hai)很大,長(chang)期(qi)這樣,會(hui)破壞(huai)本身電(dian)化學反應。
另外,不(bu)(bu)同(tong)電池容量不(bu)(bu)同(tong),充(chong)電器(qi)的電流不(bu)(bu)同(tong)。如果混用(yong),會傷(shang)害(hai)電池。像一些萬能充(chong),它(ta)的容量設計(ji)在幾百-3000毫安時,如果用(yong)大電流充(chong)小容量的電池,對電池會有損害(hai)。所以應(ying)急(ji)式充(chong)電方(fang)式應(ying)少用(yong)。
2個誤區
電池(chi)前三次使用要(yao)放空后(hou)充12個小(xiao)時?
杜教授說(shuo),這(zhe)種“前三次充電要充12小時以(yi)上”的說(shuo)法,是從(cong)鎳氫(qing)電池延續下來的說(shuo)法。這(zhe)種說(shuo)法,可(ke)以(yi)說(shuo)一開始就是誤(wu)傳(chuan)。
鋰離子電(dian)(dian)(dian)(dian)(dian)池在(zai)開始(shi)使用(yong)時不需要通過深度(du)充(chong)(chong)放(fang)電(dian)(dian)(dian)(dian)(dian)來進行(xing)激(ji)活(huo),因為電(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)激(ji)活(huo)過程在(zai)制造(zao)電(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)時候就已經(jing)完成(cheng)了,在(zai)出廠前的(de)(de)(de)化(hua)成(cheng)階(jie)段就是恒壓充(chong)(chong)電(dian)(dian)(dian)(dian)(dian),然后放(fang)電(dian)(dian)(dian)(dian)(dian),如此(ci)進行(xing)幾(ji)個循環,使電(dian)(dian)(dian)(dian)(dian)極浸(jin)潤電(dian)(dian)(dian)(dian)(dian)解液充(chong)(chong)分活(huo)化(hua),使容(rong)量(liang)達(da)到(dao)要求,這樣出來的(de)(de)(de)鋰離子電(dian)(dian)(dian)(dian)(dian)池到(dao)用(yong)戶(hu)手上時其(qi)實(shi)已經(jing)是激(ji)活(huo)過的(de)(de)(de)了。
而鋰離子電(dian)(dian)(dian)池的恒(heng)(heng)流(liu)恒(heng)(heng)壓(ya)充電(dian)(dian)(dian)特性(xing)更是決定了它的深充電(dian)(dian)(dian)時(shi)間無需(xu)12個小時(shi),鎳氫(qing)電(dian)(dian)(dian)池需(xu)要這樣做是因為,要通過涓流(liu)充電(dian)(dian)(dian)過程(小電(dian)(dian)(dian)流(liu)充電(dian)(dian)(dian))才能使電(dian)(dian)(dian)池達(da)到充飽狀態。而鋰離子恒(heng)(heng)流(liu)充電(dian)(dian)(dian)階段,容量就達(da)到80%-90%,在(zai)恒(heng)(heng)壓(ya)充電(dian)(dian)(dian)階段1-2小時(shi)即可達(da)到100%,再延長時(shi)間充電(dian)(dian)(dian)沒有(you)太大(da)意義。
要(yao)等手機電用完再充電?
“盡量把手機電池的電量用完,最好用到自動關機再充電。”這種做法也只是鎳氫電池上的做法,目的是避免記憶效應發生,而對于鋰離子電池,沒(mei)有必要用到關機再(zai)充電(dian)(dian),鋰(li)離子電(dian)(dian)池(chi)本來(lai)就適(shi)合用隨時(shi)充電(dian)(dian)的方(fang)式進行(xing)使用,這也是它(ta)針(zhen)對鎳氫電(dian)(dian)池(chi)的最大優勢之一(yi),可以加以利(li)用。
不(bu)要(yao)以為(wei)充電(dian)次數多會損壞電(dian)池,這個說法(fa)對鋰(li)離子電(dian)池并不(bu)適用。
3個疑問
手機電量用光是(shi)否(fou)損傷電池?
手(shou)機(ji)(ji)(ji)出現低(di)電(dian)量報警,其(qi)實(shi)就是(shi)手(shou)機(ji)(ji)(ji)中的電(dian)源管理芯片(pian)在發(fa)揮作用。電(dian)壓低(di)于3.6v,電(dian)源管理芯片(pian)會強(qiang)制斷開,限制手(shou)機(ji)(ji)(ji)使用。這樣實(shi)際上還不到過(guo)放的階段。不過(guo)如果經常這樣,也是(shi)不可取的。
久充是否會使電池爆炸?
鋰離子電池的手機或充電器在(zai)(zai)電(dian)(dian)池充(chong)(chong)(chong)滿(man)后都會(hui)自動(dong)停(ting)充(chong)(chong)(chong),并不存在(zai)(zai)鎳電(dian)(dian)充(chong)(chong)(chong)電(dian)(dian)器所謂的(de)持(chi)續十幾(ji)小(xiao)時的(de)“涓流”充(chong)(chong)(chong)電(dian)(dian)。也就是說,如果你(ni)的(de)鋰離子(zi)電(dian)(dian)池在(zai)(zai)充(chong)(chong)(chong)滿(man)后,放在(zai)(zai)充(chong)(chong)(chong)電(dian)(dian)器上也是白充(chong)(chong)(chong)。不過,誰都無(wu)法保證電(dian)(dian)池的(de)充(chong)(chong)(chong)放電(dian)(dian)保護電(dian)(dian)路(lu)的(de)特性永不變(bian)化和(he)質量的(de)萬無(wu)一失,所以(yi)你(ni)的(de)電(dian)(dian)池將(jiang)長(chang)期處在(zai)(zai)危險的(de)邊緣。久充(chong)(chong)(chong)還是不提(ti)倡。
電池放(fang)著不用是(shi)否有損耗?
鋰離子電池放著不用,容量也會自然損失。研究表明,鋰離子電池在完全(quan)充電(dian)(dian)(dian)的(de)狀(zhuang)態下長時間存(cun)(cun)放(fang)(fang),其容量(liang)會發生(sheng)明顯損(sun)失(shi)。而(er)(er)且,溫度越高(gao),鋰(li)離子電(dian)(dian)(dian)池(chi)的(de)容量(liang)損(sun)失(shi)就越快,而(er)(er)這(zhe)種損(sun)失(shi)是不可逆的(de),也就是說,電(dian)(dian)(dian)池(chi)的(de)容量(liang)會永久變小。在0℃環(huan)境(jing)(jing)下,電(dian)(dian)(dian)量(liang)剩(sheng)余40%的(de)鋰(li)離子電(dian)(dian)(dian)池(chi)存(cun)(cun)放(fang)(fang)一(yi)年(nian)后,其容量(liang)會損(sun)失(shi)2%。而(er)(er)在40℃環(huan)境(jing)(jing)下,完全(quan)充滿電(dian)(dian)(dian)的(de)鋰(li)離子電(dian)(dian)(dian)池(chi)存(cun)(cun)放(fang)(fang)一(yi)年(nian)后,其容量(liang)損(sun)失(shi)高(gao)達35%。因(yin)此,一(yi)定要細心地注(zhu)意使(shi)用環(huan)境(jing)(jing),防止高(gao)溫現象,比如手機放(fang)(fang)在汽車的(de)前(qian)臺上,中(zhong)午的(de)太陽直(zhi)射(she)很(hen)容易(yi)就可以(yi)使(shi)其超(chao)過(guo)60℃。