1.鎳(nie)氫電池充放電特性

（1）充電特性

鎳氫電池充電特性曲線大(da)致可分為三段。

開(kai)(kai)(kai)始(shi)時(shi)電(dian)(dian)(dian)(dian)壓(ya)(ya)上升(sheng)(sheng)較(jiao)快，然后(hou)比較(jiao)平坦(tan)。這是由(you)于Ni（OH），導電(dian)(dian)(dian)(dian)性(xing)極(ji)(ji)(ji)(ji)差但充電(dian)(dian)(dian)(dian)產物NiOOH導電(dian)(dian)(dian)(dian)性(xing)是前者的(de)(de)(de)I0倍，因(yin)(yin)而充電(dian)(dian)(dian)(dian)剛開(kai)(kai)(kai)始(shi)時(shi)，電(dian)(dian)(dian)(dian)壓(ya)(ya)上升(sheng)(sheng)很快。有NiOOH生成后(hou)，充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)(ya)上升(sheng)(sheng)速(su)(su)率(lv)降低，電(dian)(dian)(dian)(dian)壓(ya)(ya)變得(de)比較(jiao)平坦(tan)。隨著充電(dian)(dian)(dian)(dian)過(guo)(guo)程的(de)(de)(de)進(jin)(jin)行(xing)，當(dang)充電(dian)(dian)(dian)(dian)容量接近(jin)電(dian)(dian)(dian)(dian)池的(de)(de)(de)額(e)定容量的(de)(de)(de)75%左右時(shi)，儲氫(qing)合金中(zhong)(zhong)的(de)(de)(de)氫(qing)原子擴(kuo)散(san)速(su)(su)度(du)減(jian)慢。由(you)于氧(yang)在(zai)儲氫(qing)合金中(zhong)(zhong)的(de)(de)(de)擴(kuo)散(san)速(su)(su)度(du)受負極(ji)(ji)(ji)(ji)反(fan)應速(su)(su)度(du)的(de)(de)(de)限制(zhi)，以及此時(shi)正(zheng)極(ji)(ji)(ji)(ji)開(kai)(kai)(kai)始(shi)逐(zhu)步析(xi)出(chu)氧(yang)氣(qi)，因(yin)(yin)而充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)(ya)就(jiu)(jiu)再次呈現快速(su)(su)上升(sheng)(sheng)的(de)(de)(de)趨勢。當(dang)充電(dian)(dian)(dian)(dian)量超過(guo)(guo)電(dian)(dian)(dian)(dian)池設計容量之后(hou)就(jiu)(jiu)進(jin)(jin)入(ru)過(guo)(guo)充電(dian)(dian)(dian)(dian)階段。此時(shi)正(zheng)極(ji)(ji)(ji)(ji)析(xi)出(chu)的(de)(de)(de)氧(yang)會在(zai)負極(ji)(ji)(ji)(ji)儲氫(qing)合金表面(mian)進(jin)(jin)行(xing)還原、去極(ji)(ji)(ji)(ji)化，使負極(ji)(ji)(ji)(ji)電(dian)(dian)(dian)(dian)位正(zheng)移(yi)，電(dian)(dian)(dian)(dian)池溫度(du)迅速(su)(su)升(sheng)(sheng)高，加之鎳(nie)氫(qing)電(dian)(dian)(dian)(dian)池反(fan)應溫度(du)系數(shu)是負值，因(yin)(yin)此電(dian)(dian)(dian)(dian)池的(de)(de)(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)(ya)就(jiu)(jiu)會下降。

鎳氫電(dian)(dian)(dian)池(chi)常用恒(heng)流充電(dian)(dian)(dian)的(de)(de)(de)方式進(jin)行(xing)充電(dian)(dian)(dian)，在充電(dian)(dian)(dian)過(guo)程(cheng)中電(dian)(dian)(dian)池(chi)所達到的(de)(de)(de)最(zui)高(gao)電(dian)(dian)(dian)壓(ya)是鎳氫電(dian)(dian)(dian)池(chi)的(de)(de)(de)一(yi)個重(zhong)要(yao)特(te)性(xing)。充電(dian)(dian)(dian)最(zui)高(gao)電(dian)(dian)(dian)壓(ya)往(wang)(wang)往(wang)(wang)標志著整個充電(dian)(dian)(dian)過(guo)程(cheng)的(de)(de)(de)電(dian)(dian)(dian)壓(ya)=充電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)越(yue)低(di)，說(shuo)明電(dian)(dian)(dian)池(chi)在充電(dian)(dian)(dian)過(guo)程(cheng)中的(de)(de)(de)極化就越(yue)小，電(dian)(dian)(dian)池(chi)的(de)(de)(de)充電(dian)(dian)(dian)效率就越(yue)高(gao)，電(dian)(dian)(dian)池(chi)的(de)(de)(de)使用壽命就可能越(yue)長。

采用該方法，充(chong)電過程的終點控制(zhi)是一(yi)個(ge)非(fei)常(chang)實際的問(wen)題.充(chong)電終點控制(zhi)的方式(shi)主要有：

1）定時(shi)控制(zhi)。設置一定的充電時(shi)間來控制(zhi)充電終點，一般設定要充入110%額定容量(liang)所需的時(shi)間來控制(zhi)。

2）TCO，即(ji)最高(gao)溫度控制。考慮電(dian)池(chi)(chi)的安全(quan)和特性應當避(bi)免(mian)高(gao)溫充電(dian)，一般電(dian)池(chi)(chi)溫度升高(gao)到60℃時應當停止(zhi)充電(dian)。

3）電(dian)壓峰(feng)值(zhi)控制。充電(dian)過程(cheng)中電(dian)池的電(dian)壓達到峰(feng)值(zhi)并保持，即

△V=0，據(ju)此來判斷充電的終點(dian)。

4）dT/dt即深度變(bian)化率控(kong)制。通過檢測電池溫(wen)度變(bian)化率峰值來判斷充電的終點。

5）AT，即(ji)溫(wen)度(du)差控制。溫(wen)度(du)差為電池充滿電時溫(wen)度(du)與環(huan)境溫(wen)度(du)之差.

6）-△V，即電壓降控(kong)制。當(dang)電池充滿電時，電壓達(da)到峰值后會下降一(yi)定的(de)值，據(ju)此判斷(duan)充電終點。

（2）放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)特性(xing)鎳(nie)氫(qing)(qing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池工作電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)為1.2V，指(zhi)的(de)(de)是放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)平臺電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)。它是鎳(nie)氫(qing)(qing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)重要性(xing)能(neng)指(zhi)標(biao)。鎳(nie)氫(qing)(qing)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)性(xing)能(neng)隨放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)、溫度(du)和其他因(yin)素(su)的(de)(de)改變而(er)變化。如圖4-4所示。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)特性(xing)受電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)/環(huan)境溫度(du)等(deng)因(yin)素(su)的(de)(de)影響，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)越(yue)大，溫度(du)越(yue)低(di)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)和放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)效率越(yue)低(di)，長期大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)放(fang)(fang)(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)壽命也會造(zao)成一定的(de)(de)影響。截(jie)止(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)一般設定在(zai)0.9~1.V，如果截(jie)止(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)設定得太高，則(ze)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池容量(liang)不(bu)能(neng)被(bei)充分利用，反之(zhi)，則(ze)容易引起電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池過放(fang)(fang)(fang)(fang)(fang)。

2.容量特性

電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)實(shi)(shi)際容(rong)量受到理論容(rong)量的(de)(de)(de)限制，但與實(shi)(shi)際放(fang)電(dian)(dian)(dian)(dian)(dian)機(ji)制和應(ying)用工況密切相關。在高(gao)倍率(lv)即大電(dian)(dian)(dian)(dian)(dian)流(liu)放(fang)電(dian)(dian)(dian)(dian)(dian)條件(jian)F，電(dian)(dian)(dian)(dian)(dian)極的(de)(de)(de)極化增強，內阻增大，放(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓下降(jiang)很快，電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)能量效率(lv)降(jiang)低，電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)實(shi)(shi)際容(rong)量一般都低于額(e)(e)定容(rong)量。相應(ying)地(di)，在低倍率(lv)放(fang)電(dian)(dian)(dian)(dian)(dian)條件(jian)下，放(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓下降(jiang)緩慢(man).電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)實(shi)(shi)際放(fang)出的(de)(de)(de)容(rong)量常常高(gao)于額(e)(e)定容(rong)量。鎳氫電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)、擱置時間、放(fang)電(dian)(dian)(dian)(dian)(dian)終止(zhi)電(dian)(dian)(dian)(dian)(dian)壓和放(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)等均會對放(fang)電(dian)(dian)(dian)(dian)(dian)容(rong)量產(chan)生影響。

（1）充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)對放(fang)電(dian)(dian)(dian)(dian)容(rong)(rong)量的影響充(chong)電(dian)(dian)(dian)(dian)負極反(fan)應(ying)方程(cheng)式(shi)中消耗(hao)電(dian)(dian)(dian)(dian)荷生(sheng)成OH，電(dian)(dian)(dian)(dian)荷不能再釋放(fang)利(li)用，因而電(dian)(dian)(dian)(dian)池的充(chong)電(dian)(dian)(dian)(dian)效率(lv)總是小(xiao)于100%。隨(sui)充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)倍率(lv)增(zeng)大，電(dian)(dian)(dian)(dian)極極化增(zeng)加(jia)，將(jiang)加(jia)劇鎳氫電(dian)(dian)(dian)(dian)池中氧氣(qi)析出的復合反(fan)應(ying)，導致充(chong)電(dian)(dian)(dian)(dian)效率(lv)和(he)放(fang)電(dian)(dian)(dian)(dian)容(rong)(rong)量降低。

基于(yu)該反(fan)應原理(li)，放(fang)(fang)(fang)電(dian)容(rong)(rong)(rong)量(liang)隨充電(dian)容(rong)(rong)(rong)量(liang)的變(bian)化也體現(xian)為隨充電(dian)過(guo)程(cheng)進(jin)行，電(dian)池(chi)SOC升高(gao)，電(dian)池(chi)可放(fang)(fang)(fang)電(dian)容(rong)(rong)(rong)量(liang)增加，初期可放(fang)(fang)(fang)電(dian)容(rong)(rong)(rong)量(liang)增加較(jiao)快，隨充電(dian)過(guo)程(cheng)中復(fu)合反(fan)應出現(xian)，可放(fang)(fang)(fang)電(dian)容(rong)(rong)(rong)量(liang)增加速度(du)減緩，最終可放(fang)(fang)(fang)電(dian)容(rong)(rong)(rong)量(liang)將達到穩定值。

（2）擱置(zhi)時間對(dui)放電(dian)(dian)容量的(de)(de)影(ying)響(xiang)擱置(zhi)時間對(dui)鎳氫電(dian)(dian)池放電(dian)(dian)容量的(de)(de)影(ying)響(xiang)本(ben)質上就是鎳氫電(dian)(dian)池的(de)(de)自放電(dian)(dian)問題(ti)。擱置(zhi)時間對(dui)放電(dian)(dian)容量的(de)(de)影(ying)響(xiang)是由于金屬氧化物不穩(wen)定(ding)引起(qi)的(de)(de)，這(zhe)種不穩(wen)定(ding)性在剛充完電(dian)(dian)或高荷電(dian)(dian)狀態時表(biao)現尤為(wei)明(ming)顯，而(er)(er)后漸(jian)趨平(ping)衡和穩(wen)定(ding)，因(yin)而(er)(er)鎳氫電(dian)(dian)池放電(dian)(dian)容量隨擱置(zhi)時間的(de)(de)延長而(er)(er)下降，擱置(zhi)的(de)(de)開始階段容量下降較快。

（3）放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流對(dui)放電(dian)(dian)(dian)(dian)容(rong)量的影響(xiang)電(dian)(dian)(dian)(dian)池內(nei)阻(zu)主要(yao)包括歐姆內(nei)阻(zu)和(he)電(dian)(dian)(dian)(dian)化學(xue)(xue)極(ji)化內(nei)阻(zu)兩部(bu)分。歐姆內(nei)阻(zu)對(dui)一特定的電(dian)(dian)(dian)(dian)池來(lai)說(shuo)也(ye)是(shi)一個(ge)(ge)定值(zhi)，電(dian)(dian)(dian)(dian)化學(xue)(xue)極(ji)化內(nei)阻(zu)則與(yu)發(fa)生電(dian)(dian)(dian)(dian)化學(xue)(xue)反應時的極(ji)化狀態有(you)關，而(er)放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流是(shi)影響(xiang)電(dian)(dian)(dian)(dian)極(ji)極(ji)化狀態的一個(ge)(ge)重(zhong)要(yao)因素。放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流增(zeng)大，電(dian)(dian)(dian)(dian)極(ji)極(ji)化也(ye)增(zeng)大，電(dian)(dian)(dian)(dian)化學(xue)(xue)極(ji)化內(nei)阻(zu)就大，其端電(dian)(dian)(dian)(dian)壓(ya)相對(dui)較低(di)。對(dui)于相同(tong)的放電(dian)(dian)(dian)(dian)終止電(dian)(dian)(dian)(dian)壓(ya)來(lai)說(shuo)，最終反映為放電(dian)(dian)(dian)(dian)容(rong)量測(ce)試(shi)結果較低(di)。

（4）放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)終(zhong)(zhong)(zhong)止電(dian)(dian)(dian)(dian)(dian)壓(ya)對(dui)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)容量(liang)的影(ying)響(xiang)(xiang)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)終(zhong)(zhong)(zhong)止電(dian)(dian)(dian)(dian)(dian)壓(ya)直接影(ying)響(xiang)(xiang)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)時間(jian)，而(er)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)容量(liang)實際是(shi)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流(liu)與放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)時間(jian)的乘積(ji)，因(yin)而(er)放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)容量(liang)隨放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)終(zhong)(zhong)(zhong)止電(dian)(dian)(dian)(dian)(dian)壓(ya)的降(jiang)低而(er)增加。但鎳氫電(dian)(dian)(dian)(dian)(dian)池(chi)的放(fang)(fang)(fang)電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)壓(ya)不能無限地降(jiang)低，一般選定在0.9V左右(you)。

過低(di)將(jiang)出現過放電現象，影響鎳氫電池的使用壽命(ming)。

3.內壓

鎳氫電(dian)池(chi)內(nei)(nei)壓產生的基本原因是電(dian)池(chi)在充(chong)放(fang)電(dian)過(guo)程中，正極(ji)析出氧氣和負極(ji)析出氫氣。從而產生電(dian)池(chi)的內(nei)(nei)壓。鎳氫電(dian)池(chi)的內(nei)(nei)壓是直(zhi)存(cun)在的，通常(chang)都維(wei)持在正常(chang)水平，不會引起安(an)全(quan)問題(ti)。但在過(guo)充(chong)或過(guo)放(fang)情況下，電(dian)池(chi)內(nei)(nei)壓升(sheng)高(gao)到一定程度，就有(you)(you)可能帶來安(an)全(quan)問題(ti)鎳氫電(dian)池(chi)的內(nei)(nei)壓與充(chong)電(dian)方(fang)式(shi)及荷電(dian)狀態有(you)(you)關。

當電(dian)池荷電(dian)狀態達到(dao)100%以前，內壓增加平緩，當荷電(dian)超過1000后，內壓急劇增加。因(yin)此，過充電(dian)的鎳氫電(dian)池存在一定的安全隱患。

試驗數(shu)(shu)據表明，隨(sui)著電(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)、放電(dian)(dian)(dian)(dian)循環次數(shu)(shu)增加，內(nei)壓也(ye)會(hui)逐漸升高(gao)，同時電(dian)(dian)(dian)(dian)池中氫、氧氣體比(bi)例也(ye)會(hui)發(fa)生變化。鎳氫電(dian)(dian)(dian)(dian)池中電(dian)(dian)(dian)(dian)解(jie)液(ye)的量也(ye)會(hui)影響(xiang)電(dian)(dian)(dian)(dian)池內(nei)壓，電(dian)(dian)(dian)(dian)解(jie)液(ye)過多會(hui)使內(nei)壓升得很高(gao)。