充電器充電的電池簡稱二次電池
和普(pu)通(tong)的不可充電的電池(chi)相(xiang)比(bi),可充電的電池叫(jiao)二次(ci)電池。二次(ci)電池能夠反復運(yun)用,符合(he)經濟實用原則(ze),這是其最大的優點,自(zi)然人們最青睞二次(ci)電池。二次(ci)電池的種類也不少,就目前(qian)市場上(shang)主流產(chan)品而言,有 4類電池:鉛(qian)酸(LA)電(dian)池、鎳鎘(NiCd)電(dian)池、鎳氫(qing)(NiMH)電池和鋰離子(Liion )電池。
1.便(bian)攜式電子設備可選擇(ze)的電源系統(tong)
對(dui)便(bian)攜式電(dian)(dian)(dian)子(zi)(zi)設備的(de)(de)生(sheng)產商來(lai)說(shuo),給便(bian)攜式電(dian)(dian)(dian)子(zi)(zi)設備選擇(ze)合適的(de)(de)電(dian)(dian)(dian)池(chi)(chi)是很困難的(de)(de)。因為(wei)電(dian)(dian)(dian)池(chi)(chi)的(de)(de)選擇(ze)會對(dui)設備的(de)(de)功能、型號、成(cheng)本(ben)造成(cheng)很大(da)的(de)(de)影響(xiang)。設計者面(mian)對(dui)著很多選擇(ze),從簡單的(de)(de)鉛(qian)酸電(dian)(dian)(dian)池(chi)(chi)到(dao)復雜的(de)(de)集成(cheng)了電(dian)(dian)(dian)子(zi)(zi)安全、監視和充電(dian)(dian)(dian)控制電(dian)(dian)(dian)路(lu)的(de)(de)鋰離子(zi)(zi)電(dian)(dian)(dian)池(chi)(chi)。
1)鎳鎘電(dian)池。
鎳鋼電池(chi)工作電壓(ya)為(wei)1.2V左右(you),具有優良的大(da)電(dian)流放(fang)電(dian)性能(neng),可在一20~
鎳鎘電(dian)(dian)池(chi)種(zhong)類(lei)繁多,有放置(zhi)用的大型電(dian)(dian)池(chi)(多數20Ah以上)和小型密封型電池,6Ah以(yi)下(xia)的圓柱形(xing)和扁(bian)平形(xing)電(dian)池(chi),0.5Ah以下的紐扣(kou)式電(dian)池。日本三洋公司生(sheng)產40~2000mAh的 95種型號的鎳鎘(ge)電池,按用途(tu)有 8類電(dian)池:一般用(標準型)、 高(gao)容量(E型)、 快速充電用(R型(xing))、 高溫(wen)用(H型)、耐(nai)熱用(K型(xing))、 長壽命(C型)、保護記憶(yi)用(yong)(S型)、 扁平(ping)形(KF型)、標準型典型電池為 AA型,容量(liang)為600mAh,尺寸為14.2mmX 50.
質量(liang)為 23克,內阻為(wei)12mΩ。AAA型(xing)的容(rong)量為 250mAh,尺寸為10.5mm X 44.5mm,質量(liang)為11克,內阻24Ω。
鎳鎘電池正極板上的活性物質由氧化鎳粉和石墨粉組成,石墨不參加化學反應,其主要作用是增強導電性。負極板上的活性物質由氧化鋁粉和氧化鐵粉組成,氧化鐵粉的作用是使氧化鋁粉有較高的擴散性,防止結塊,并增加極板的容量。活性物質分別包在穿孔鋼帶中,加壓成型后即成為電池的正負極板。極板間用耐堿的硬橡膠絕緣棍或有孔的聚氯乙烯瓦楞板隔開。電解液通常用氫氧化鉀溶液。與其他電池相比,鎳錫電池的自放電率(電池不使用時失去電荷的速率)適中。鎳鎘電池在使用過程中,如果放電不完全就又充電,下次再放電時,就不能放出全部的電量。比如,放出80%電量后再充足電,該電池只能放出80%的電量,這就是所謂的記憶效應。當然,幾次完整的放電/充電循環將使鎳鎘電池恢復正常工作。
由于鎳鎘電池的記憶效應,若未完全放電,應在充電前將每節電池放電至 1V以下。
2)鎳氫電池。鎳氫電池是生產了幾年的新電池,又稱為貯氫電池。20世紀70年代,荷蘭飛利浦實驗室在研究第一代稀土永磁合金時,試驗了LaNi5的磁性能,競意外地發現了 LaNi5有很好的貯氫性能,但深入研究發現對貯氫合金不適用,因為平衡壓太高,循環壽命太短,進一步研究和改進發現,這些缺點都可克服,從而為發展貯氫電池奠定了技術基礎。
兩者有相同的工作電壓1.2V,因此這兩種電池有良好的互換性。
鎳氫電池的能量高,為鎳鎘電池的1.8~2倍,鉛酸電池的3倍,有良好的充放電性能,可隨充隨放,快充深放,無記憶效應,特別不含鎘、鉛、汞等有害物質,對環境無污染,被稱為綠色電池。
鎳氫電池與鎳鎘電池類似,多種多樣。有圓柱形和扁平形的小電池,有紐扣式電池,也有方形蓄電池組作為動力電池用,容量為10~20Ah。日本三洋公司生產的 AA型的容量為1100mAh,尺寸為 14.2mm X 50.0mm,質量為27克,AAA型的容量為 650mAh,尺寸為10.
鎳氫電池具有較好的低溫放電特性,即使在一
鎳鎘電池與鎳氫電池的充電過程非常相似,都要求恒流充電。兩者的差別主要在快速充電的終止檢測方法上,以防止電池過充電。充電器對電池進行恒流充電,同時檢測電池的電壓和其他參數。當電池電壓緩慢上升達到一個峰值時,對鎳氫電池快速充電終止,而鎳鎘電池則當電池電壓第一次下降了一個ΔV時終止快速充電。為避免損壞電池,電池溫度過低時不能開始快速充電,電池溫度 Tmin低于
3)鋰離子電池。鋰離子電池是繼鎳氫電池后發展的新一代的二次電池。鋰位于元素周期表第一族主族第一位上,是金屬中最輕的元素,有最負的標準電位,組成電池能量密度大和電壓高。鋰離子電池負極電位相對鋰電極為正,正極電位為4.OV,該電池的工作電壓高,約3.6V。高電壓是個優點,一個鋰離子電池相當于三個鎳氫電池或鎳鎘電池,但這也是個缺點,因為移動電話芯片電壓趨向下降,這將挑戰3.6V 鋰離子電池的應用。鋰離子電池有高的比能量,為鎳氫電池的1.5倍和鉛酸電池的3倍,放電曲線平穩,自放電率低,循環壽命長,與鎳氫電池一樣,無記憶效應和不污染環境,也為綠色電池。
鋰離子電池采用卷繞式結構,蓋體設計強化了安全保護功能。對于這種高比能量電池,必須經過規范的安全檢測評估。鎳氫和鎳鎘電池的電解液是水溶液,而鋰離子電池必需用非水性電解液,其電導率低得多,因此電極要大大減薄,有著不同的電極制備工藝,制備又薄又長的正負電極。鋰離子電池同樣有圓柱式、扁平式、紐扣式和動力用電池組。Sony公司的 14500電池容量為 500mAh,尺寸為 14.3mmX 50.
鋰離子電池能夠很好地配合電子產品小型化、袖珍化的發展方向,移動電話和筆記本電腦要求又薄又輕的二次電池,三洋超薄鋰離子電池僅
鋰離子(zi)電池(chi)易受到過(guo)充(chong)電、深放電以及短路的(de)損害。單體鋰離子(zi)電池(chi)的(de)充(chong)電電壓必須嚴格限制。充(chong)電速(su)率通常不超過(guo)
2.二次電(dian)池性(xing)能比較
表(biao)1。l為鉛酸、鎳(nie)銅、鎳(nie)氫、鋰離子電池特性的比較(jiao)。
20世(shi)紀(ji)80年(nian)代的(de)便攜(xie)式(shi)電(dian)子(zi)設備(bei),如數(shu)字(zi)無繩電(dian)話、隨(sui)身聽和電(dian)動剃須刀等,主要由鎳鎘電(dian)池供(gong)電(dian)。到了20世(shi)紀(ji)90年代后期(qi),鎳(nie)氫電池(chi)(chi)和(he)鋰離(li)子(zi)電池(chi)(chi)逐漸進入市場(chang)并得(de)以廣泛應用。因為鎳(nie)鎘電池(chi)(chi)的(de)價(jia)格(ge)比(bi)鎳(nie)氫和(he)鋰離(li)子(zi)電池(chi)(chi)便宜,所以鎳(nie)鎘電池(chi)(chi)在低端應用中十分普遍。鎳(nie)鎘電池(chi)(chi)可提供最(zui)高的(de)放電電流(liu),適合短時間內需要大功率輸出的(de)應用。
鎳(nie)鎘(ge)電(dian)池(chi)的(de)缺(que)點(dian)是被(bei)所謂(wei)的(de)記憶(yi)效應困擾(現(xian)在的(de)鎳(nie)鎘(ge)電(dian)池(chi)很少考慮這個因素), 使(shi)電池容量降(jiang)低(di)。鎳鎘電池在未完(wan)全放(fang)電的情(qing)況下再充(chong)電,一些活性物質會(hui)累積并且(qie)開始(shi)結晶(在陽極有100μm的銅累(lei)積層), 但通過化學(xue)反應這層物(wu)質會自行消(xiao)失(shi)(一(yi)塊全新電池的(de)陽極大約有l00μm厚度的(de)鎘結晶), 出(chu)現記憶效應會導致電池容量越來越小,端電壓越來越低,使得電池到達最低可用端電壓(關斷點)的時間比預期(qi)的早很多,如圖1-1所示(shi)。鎳鎘電池的另一(yi)個缺點是它的活(huo)性(xing)物質(zhi)中含有有毒的鎘。
鎳氫電池比鎳鎘電池環保,但是價格高。鎳氫電池的放電電流相比鎳鎘電池略小,但也受惰性效應的影響。惰性效應是比鎳鎘電池記憶效應稍輕的一種現象。惰性效應是由于鎳的結晶導致的。惰性效應和記憶效應一樣,導致無法完全使用可充電電池的全部容量,但都可以通過使用帶有放電功能的充電器來避免。
鋰離子可充電(dian)電(dian)池價格最(zui)高,但具有高的能量(liang)密度(du),因而可以在給定尺(chi)寸下提供(gong)更(geng)優性能,更(geng)適合(he)小尺(chi)寸、高集成(cheng)度(du)的便攜式電(dian)子設備。
隨著新(xin)材(cai)料、新(xin)工藝的(de)出現,更(geng)為先進耐(nai)用的(de)可(ke)再充電(dian)(dian)電(dian)(dian)池(chi)(chi)也在不斷(duan)出現。國外最(zui)新(xin)開發的(de)固(gu)態聚(ju)合(he)物(電(dian)(dian)解質)鋰離子電(dian)(dian)池(chi)(chi)、鋰金屬電(dian)(dian)池(chi)(chi)不僅解決了漏液(ye)問題,而且電(dian)(dian)池(chi)(chi)的(de)容量更(geng)大(da),體積更(geng)小,更(geng)為安全可(ke)靠,它們必將成為極有潛力的(de)新(xin)一代電(dian)(dian)池(chi)(chi)產品(pin)。
3.鎳氫/鎳鎘電池(chi)與(yu)鋰離子電池(chi)的差異
1)質量方面。以每(mei)一個單元電(dian)池的(de)電(dian)壓來看,鎳氫(qing)與(yu)鎳鎘都是1.2V,而鋰(li)離(li)子電池卻為3.6V,鋰離子電池的(de)電壓是前兩者(zhe)的(de)3倍。并且同(tong)型電(dian)池(chi)的質(zhi)量(liang)鋰離(li)子電(dian)池(chi)與(yu)鎳鎘電(dian)池(chi)幾乎相等(deng),而鎳氫電(dian)池(chi)卻(que)比較重。每一(yi)種(zhong)電(dian)池(chi)本身質(zhi)量(liang)不(bu)同(tong),但(dan)鋰離(li)子電(dian)池(chi)因3.6V高(gao)電(dian)壓,在(zai)輸出同等電(dian)壓的情況下使(shi)單個(ge)電(dian)池組合時數目可減少 1/3而使成(cheng)型后的(de)電池質量(liang)和體(ti)積減小。
2)記(ji)憶效應(ying)。鎳(nie)氫(qing)電(dian)(dian)(dian)(dian)池有惰性效應(ying);鎳(nie)鎘電(dian)(dian)(dian)(dian)池有記(ji)憶效應(ying),因此,定期的放(fang)電(dian)(dian)(dian)(dian)管理(li)也(ye)是必需的。這種定期放(fang)電(dian)(dian)(dian)(dian)管理(li)屬于模(mo)糊狀(zhuang)態下被動處理(li),甚(shen)至也(ye)有些在不正確的情況下進行(xing)放(fang)電(dian)(dian)(dian)(dian)(每次放(fang)電(dian)(dian)(dian)(dian)或(huo)者使用幾次后進行(xing)放(fang)電(dian)(dian)(dian)(dian)都因電(dian)(dian)(dian)(dian)池生產廠(chang)的不同而有所差異), 這(zhe)種繁瑣的放電管理(li)在使用鎳鎘(ge)/鎳氫電池時是無法避免的。相對的鋰離子電池因為完全沒有記憶效應,在使用上非常方便簡單,它完全不必考慮二次電池殘余電壓的多少,直接可進行充電,充電時間自然可以縮短。
記(ji)憶(yi)效(xiao)(xiao)應是充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)一(yi)大天敵,一(yi)般認(ren)為是長期(qi)不正確的(de)(de)充(chong)(chong)電(dian)(dian)(dian)導致的(de)(de),它(ta)可(ke)以使電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)早衰。記(ji)憶(yi)效(xiao)(xiao)應可(ke)使電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)無法(fa)有效(xiao)(xiao)地充(chong)(chong)電(dian)(dian)(dian),出(chu)現(xian)一(yi)充(chong)(chong)就(jiu)滿(man)、一(yi)用(yong)就(jiu)完的(de)(de)現(xian)象。防止(zhi)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)出(chu)現(xian)記(ji)憶(yi)效(xiao)(xiao)應的(de)(de)方(fang)法(fa)是確保電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)“充(chong)(chong)足(zu)(zu)放(fang)光”的(de)(de)原則(ze),也就(jiu)是說在充(chong)(chong)電(dian)(dian)(dian)前最好將電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)內殘余電(dian)(dian)(dian)量(liang)放(fang)光,充(chong)(chong)電(dian)(dian)(dian)時要一(yi)次(ci)(ci)充(chong)(chong)足(zu)(zu)。通常鎳鎘(ge)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)容易出(chu)現(xian)記(ji)憶(yi)效(xiao)(xiao)應,所以充(chong)(chong)電(dian)(dian)(dian)時要特別注意,鎳氫電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)理(li)論上沒有記(ji)憶(yi)效(xiao)(xiao)應,但最好也遵循“充(chong)(chong)足(zu)(zu)放(fang)光”的(de)(de)原則(ze),這也就(jiu)是很(hen)多充(chong)(chong)電(dian)(dian)(dian)器提供放(fang)電(dian)(dian)(dian)附加功能的(de)(de)原因。對(dui)于(yu)由于(yu)記(ji)憶(yi)效(xiao)(xiao)應引起容量(liang)下降的(de)(de)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi),可(ke)以通過一(yi)次(ci)(ci)性充(chong)(chong)足(zu)(zu)再(zai)一(yi)次(ci)(ci)性放(fang)光的(de)(de)方(fang)法(fa)反復(fu)數次(ci)(ci),大部(bu)分電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)都可(ke)以得到(dao)修復(fu)。
3)自放(fang)電(dian)率(lv)。鎳鎘電(dian)池的(de)自放(fang)電(dian)率(lv)為(wei)15%~30%(月), 鎳氫電(dian)池的自放(fang)電(dian)率為(wei)25%~35%(月),鋰(li)離(li)子電(dian)池的自放電(dian)率為2%~5%(月),鎳氫(qing)電池的(de)自放(fang)(fang)電率最(zui)大,而鋰離子電池的(de)自放(fang)(fang)電率最(zui)低。
4)充(chong)(chong)電(dian)(dian)方式(shi)。充(chong)(chong)電(dian)(dian)電(dian)(dian)池的(de)充(chong)(chong)電(dian)(dian)方式(shi)一直(zhi)是人們關心的(de)焦點,正確、良好的(de)充(chong)(chong)電(dian)(dian)方法可以確保電(dian)(dian)池的(de)壽命。充(chong)(chong)電(dian)(dian)電(dian)(dian)池推薦的(de)充(chong)(chong)電(dian)(dian)方法多種多樣,不(bu)同(tong)的(de)充(chong)(chong)電(dian)(dian)方法對充(chong)(chong)電(dian)(dian)器的(de)電(dian)(dian)路結構(gou)有不(bu)同(tong)的(de)要求(qiu),自然影(ying)響到成本(ben)。
電(dian)(dian)池充電(dian)(dian)時間(jian)和充電(dian)(dian)電(dian)(dian)流的關系為(wei)電(dian)(dian)池容(rong)量除(chu)以(yi)充電(dian)(dian)電(dian)(dian)流得到(dao)充電(dian)(dian)時間(jian),考慮充電(dian)(dian)過程中的損(sun)耗,所(suo)以(yi)將計(ji)算得到(dao)的充電(dian)(dian)時間(jian)應(ying)再乘以(yi)1.2這個常數。
對于鎳(nie)鎘(ge)和鎳(nie)氫電池最常用的簡單充電方法是利用10%C恒流(liu)充電,又被(bei)稱為“慢充”,即按照(zhao)電流(liu)容量數值(zhi)的10%確定充電電流,如一節標(biao)稱容量為500mAh的電池(chi),它(ta)的建(jian)議充電電流為50mA;又(you)如(ru)一節標稱容量為1300mAh的(de)電(dian)池,它的(de)建(jian)議充電(dian)電(dian)流為13 0 mA。在此電流下(xia)連(lian)續充電12~15 h就(jiu)可以視(shi)為電池充滿。雖(sui)然建議使用(yong)恒流(liu)充電但要求(qiu)并不嚴格,電流(liu)允許有較(jiao)大的(de)波動,所以按照此方法(fa)制作的(de)充電器結構非常簡單(dan),一般只(zhi)需要一個將220V市電轉(zhuan)換成適(shi)當低壓的變(bian)壓器(qi)、整(zheng)流(liu)的二(er)極(ji)管(guan)、限(xian)流(liu)電阻(zu)以(yi)及一些發(fa)光(guang)二(er)極(ji)管(guan)等指示裝置構成低成本(ben)的充(chong)(chong)電器(qi),市面上絕大部分獨立(li)常(chang)規充(chong)(chong)電器(qi)都采用(yong)這種方式(shi),只不過(guo)外形不同罷了(le)。“慢充(chong)(chong)”雖(sui)然比較簡單,但(dan)是給(gei)電池(chi)充(chong)(chong)一次電需(xu)要(yao)十(shi)多個小時(shi),為此,電池(chi)廠商(shang)也允許在(zai)急需(xu)使(shi)用(yong)時(shi)用(yong) 3 0%C的電流給電池充電 4~5 h,稱之為(wei)“快充”,不(bu)過不(bu)建議(yi)常(chang)用(yong)(yong),理論(lun)上對電池有(you)輕(qing)微的損害。所以大部分(fen)常(chang)規充電器都有(you)“快充”和“慢充”兩擋,并建議(yi)用(yong)(yong)戶使用(yong)(yong)“慢充”。
在很多情況下用戶需要(yao)(yao)(yao)對(dui)電(dian)(dian)(dian)池快速(su)、有效(xiao)、安(an)全地充(chong)(chong)(chong)電(dian)(dian)(dian),快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)就需要(yao)(yao)(yao)使用較大(da)的(de)(de)電(dian)(dian)(dian)流。電(dian)(dian)(dian)池在大(da)電(dian)(dian)(dian)流充(chong)(chong)(chong)電(dian)(dian)(dian)過(guo)程(cheng)中會(hui)出現(xian)極(ji)化效(xiao)應(ying)(ying),使電(dian)(dian)(dian)池發熱,而且當大(da)電(dian)(dian)(dian)流充(chong)(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)池充(chong)(chong)(chong)滿(man)后,如果(guo)不及(ji)時(shi)停止(zhi),電(dian)(dian)(dian)池會(hui)迅速(su)發熱,嚴重時(shi)可(ke)導(dao)致電(dian)(dian)(dian)池燒毀(hui)和(he)爆炸。所以(yi)要(yao)(yao)(yao)求快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)具備充(chong)(chong)(chong)滿(man)自停功能(neng),同時(shi)也要(yao)(yao)(yao)解決極(ji)化效(xiao)應(ying)(ying),使充(chong)(chong)(chong)電(dian)(dian)(dian)高效(xiao)安(an)全。早(zao)期的(de)(de)快速(su)充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)采(cai)用簡單的(de)(de)定時(shi)充(chong)(chong)(chong)電(dian)(dian)(dian),不過(guo)此類充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)針對(dui)性強,充(chong)(chong)(chong)電(dian)(dian)(dian)效(xiao)果(guo)也不令人滿(man)意。現(xian)代的(de)(de)充(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)采(cai)用專用的(de)(de)充(chong)(chong)(chong)電(dian)(dian)(dian)控制IC,以高頻脈動(dong)電(dian)流給電(dian)池充(chong)(chong)電(dian)以解決極化效應,通過檢測電(dian)池一出準確判(pan)斷電(dian)池是否充(chong)(chong)滿,并提供溫(wen)度(du)保護(hu)(hu)等保護(hu)(hu)措施和放電(dian)等附加功(gong)能(neng)。不(bu)過這(zhe)種充(chong)(chong)電(dian)器結構比較復雜,成(cheng)本也比較高,一般多用于移(yi)動(dong)電(dian)話、對講機等高檔通信設備(bei)及電(dian)器。
6.各種電池(chi)的(de)優缺點
鎳(nie)鎘電池(chi)最為堅固耐用,每(mei)塊鎳(nie)鋼電池(chi)的(de)電壓為1.2V,多(duo)數(shu)應用(yong)需要(yao)多(duo)個電(dian)池(chi)串聯或并聯才能滿足要(yao)求。鎳鎘電(dian)池(chi)應用(yong)中(zhong)的最大(da)問題是它(ta)具有記憶效應,這一點嚴重限制了它(ta)在高端設備中(zhong)的應用(yong)。
考慮到回(hui)收和環(huan)保(bao)問題(ti),鎳鎘電(dian)池在其他(ta)產品(pin)中的(de)應用也(ye)(ye)較(jiao)少。與其他(ta)電(dian)池相(xiang)(xiang)比,鎳鎘電(dian)池的(de)耗電(dian)率、使用壽命都令人非(fei)常滿意,而且在極差的(de)溫度條件下也(ye)(ye)能保(bao)持良(liang)好(hao)的(de)性(xing)能。但是,盡管(guan)鎳鎘電(dian)池比較(jiao)經濟,但它(ta)的(de)電(dian)量也(ye)(ye)較(jiao)低(di),相(xiang)(xiang)同的(de)鎳鎘電(dian)池工(gong)作(zuo)時間大約只(zhi)有鎳氫電(dian)池的(de)一半(ban),因(yin)此多數鎳鎘電(dian)池都沉(chen)重且體積龐大。
鎳(nie)(nie)氫電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)沒有(you)(you)鎳(nie)(nie)鎘(ge)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)那么(me)堅固耐用,在能量密度上(shang)也無法(fa)與鋰離子電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)競爭,但與鎳(nie)(nie)鎘(ge)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)相比它具有(you)(you)更(geng)佳的性(xing)價比。鎳(nie)(nie)氫電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)的電(dian)(dian)(dian)壓與鎳(nie)(nie)鎘(ge)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)的相同,每塊電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)(chi)為1.2V。由(you)于主要的(de)電(dian)池(chi)應用(yong)市(shi)場(chang)如筆記本電(dian)腦(nao)及(ji)移動電(dian)話開始(shi)轉為使(shi)用(yong)鋰(li)離子電(dian)池(chi),鎳(nie)氫(qing)電(dian)池(chi)的(de)研發(fa)有所放緩,從理論上說,現有鎳(nie)氫(qing)電(dian)池(chi)的(de)電(dian)量也快(kuai)接近其極限。因此,目前的(de)研發(fa)主要是增強(qiang)其耐用(yong)性,以便適用(yong)于電(dian)動工具和(he)混(hun)合電(dian)動汽車等(deng)其他市(shi)場(chang)。
從鋰離(li)子(zi)電(dian)池(chi)開始進入(ru)市場至今已(yi)十幾年,由(you)于(yu)日益成(cheng)熟,鋰離(li)子(zi)電(dian)池(chi)也變得更為(wei)堅固耐用(yong),價格也有所下降。單(dan)個鋰離(li)子(zi)電(dian)池(chi)的電(dian)壓(ya)力3.7V,與三節(jie)鎳鎘(ge)電(dian)池(chi)(chi)或(huo)鎳氫電(dian)池(chi)(chi)一(yi)樣。能量密度高和自放電(dian)低是鋰離子電(dian)池(chi)(chi)在(zai)市場(chang)上成功的(de)法寶,目前這種(zhong)電(dian)池(chi)(chi)還開發增加了(le)許多新的(de)性(xing)能。例(li)如,鋰離子電(dian)池(chi)(chi)廠商正(zheng)在(zai)開發無需保護電(dian)路的(de)產品,以(yi)便進一(yi)步(bu)降(jiang)低其成本。
1.2.1 鎳(nie)鎘電池的結(jie)構(gou)與特性
1899年,Waldmar Jungner在開口型鎳鎘電池(chi)中首(shou)先使用了(le)鎳極板,幾乎與(yu)此(ci)同時,Thomas Edison發明了用(yong)于電動車的(de)(de)鎳鎘電池(chi)。但因(yin)(yin)當時這些堿(jian)性蓄電池(chi)的(de)(de)極板材料(liao)(liao)比(bi)其他蓄電池(chi)的(de)(de)村料(liao)(liao)貴得多,因(yin)(yin)此(ci)實際應(ying)用(yong)受到了極大的(de)(de)限制。Jungner的鎳鎘(ge)電池經過幾次重(zhong)(zhong)要改(gai)(gai)進,性能明顯改(gai)(gai)善。其中最重(zhong)(zhong)要的改(gai)(gai)進是在1932年(nian),在鎳電(dian)池(chi)(chi)中開始使用了活性(xing)物質。將活性(xing)物質放人多孔的鎳極(ji)板中,然后再將鎳極(ji)板裝人金屬殼內。鎳鎘電(dian)池(chi)(chi)發展史(shi)上另一個重(zhong)要的里程碑(bei)是(shi)1947年密(mi)封(feng)型鎳鎘電(dian)池研制成功(gong)。在(zai)這(zhe)種(zhong)電(dian)池中,化學(xue)反應(ying)產生的(de)各種(zhong)氣體不用(yong)排(pai)出,可以在(zai)電(dian)池內部化合。密(mi)封(feng)鎳鋼(gang)電(dian)池的(de)研制成功(gong),使鎳鋼(gang)電(dian)池的(de)應(ying)用(yong)范圍大(da)大(da)增(zeng)加.
1.鎳鎘電池的特性
鎳鎘(NiCd)電(dian)池要求(qiu)恒(heng)流(liu)充電(dian),充電(dian)器(qi)對電(dian)池進(jin)行恒(heng)流(liu)充電(dian)的同(tong)時檢測電(dian)池的電(dian)壓和其(qi)他參數。當電(dian)池電(dian)壓第一次下降了一個(ge)-ΔU時(shi)終(zhong)止(zhi)快速(su)充(chong)電(dian)。為避(bi)免損(sun)壞電(dian)池,電(dian)池溫(wen)度(du)過低時(shi)不能開始快速(su)充(chong)電(dian),電(dian)池溫(wen)度(du) Tmin低于 100C時(shi),應(ying)(ying)轉入涓流充電(dian)(dian)方式。而電(dian)(dian)池溫度一(yi)旦達到規(gui)定(ding)數(shu)值后,必須立即停止(zhi)充電(dian)(dian)。密(mi)封鎳鎘電(dian)(dian)池效率高、循環壽命(ming)長、能量(liang)密(mi)度大、體積(ji)小、質量(liang)輕、結(jie)構緊湊(cou),并且不需要維護,因(yin)此(ci)在(zai)工(gong)業和消費產品中(zhong)得到了廣泛(fan)的應(ying)(ying)用。
(1)鎳鋼電池的(de)基本特性。
l)鎳鎘電池可(ke)重復500次以上的充放電,非常經濟。
2)鎳鎘電(dian)(dian)池內阻小,可供大電(dian)(dian)流的(de)放(fang)(fang)電(dian)(dian),放(fang)(fang)電(dian)(dian)時(shi)電(dian)(dian)壓的(de)變化很小,作(zuo)為(wei)直(zhi)流電(dian)(dian)源是(shi)一種(zhong)質量極佳的(de)電(dian)(dian)池。
3)因(yin)為(wei)鎳鎘(ge)電(dian)池采用完(wan)全(quan)(quan)密封式,因(yin)此不會有電(dian)解(jie)液漏(lou)出的現象(xiang),也完(wan)全(quan)(quan)不需要補充電(dian)解(jie)液。
4)與其他(ta)種(zhong)類(lei)電(dian)池相比,鎳鎘電(dian)池可耐過充電(dian)或過放電(dian),操作簡單方便。
5)鎳鎘(ge)電池在長時間的(de)放(fang)置下也(ye)不會使性(xing)能劣(lie)化,當充分充完電后即可恢復原來的(de)特性(xing)。
6)鎳鎘電(dian)池(chi)可(ke)使用在很廣(guang)的溫度范圍內。
7)因(yin)為鎳鎘電池(chi)采用金(jin)屬容器,因(yin)此具有機械的堅固性(xing)。
(2)鎳(nie)鎘電(dian)池(chi)放(fang)電(dian)特性。
l)鎳鎘電(dian)池放(fang)電(dian)電(dian)壓依據其放(fang)電(dian)電(dian)流多少有(you)些差異,大(da)體上是1.2V左右。
2)當(dang)放(fang)電(dian)(dian)達到放(fang)電(dian)(dian)終了的極限電(dian)(dian)壓稱之為“放(fang)電(dian)(dian)終止電(dian)(dian)壓”,鎳鎘電(dian)(dian)池(chi)的放(fang)電(dian)(dian)終止電(dian)(dian)壓為1.0 V/單格(ge)。
3)鎳鎘電池使用溫度范圍(wei)為一20~
4)鎳鎘電池可(ke)為一30~
5)鎳鎘(ge)電(dian)池在充電(dian)狀(zhuang)態(tai)或者是放(fang)電(dian)狀(zhuang)態(tai)保存都(dou)可以,但是比較(jiao)之(zhi)下放(fang)電(dian)狀(zhuang)態(tai)可使容量較(jiao)早恢復并且(qie)較(jiao)易被激活。
6)當(dang)鎳(nie)鎘電(dian)池在長時(shi)間放置(zhi)后,使用前必須充(chong)分(fen)地充(chong)電(dian)后再使用。
2.鎳(nie)鎘電池參數
鎳鎘電池的5個主要參數為:電池的容量、標稱電壓、內阻、放電終止電壓和充電終止電壓。電池的容量通常用Ah(安時)表(biao)示,1Ah就是能在(zai)1A的(de)電(dian)流下放電(dian)1h。單(dan)元(yuan)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)內活性物質(zhi)的(de)(de)(de)數量(liang)決定單(dan)元(yuan)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)含有的(de)(de)(de)電(dian)(dian)(dian)(dian)荷量(liang),而(er)活性物質(zhi)的(de)(de)(de)含量(liang)則由電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)使(shi)用(yong)(yong)的(de)(de)(de)材料和(he)體積(ji)決定,因此,通(tong)常電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)體積(ji)越(yue)大,容量(liang)越(yue)高。與(yu)電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)容量(liang)相關的(de)(de)(de)一個參數是電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流。電(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)充電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流通(tong)常用(yong)(yong)充電(dian)(dian)(dian)(dian)速(su)率C表示,C為(wei)電池的額定容量。例如,用2A電流對(dui)1Ah電(dian)(dian)池充(chong)電(dian)(dian),充(chong)電(dian)(dian)速率(lv)就(jiu)是2C;同樣地,用2A電流對500mAh電(dian)池充電(dian),充電(dian)速率(lv)就(jiu)是 4C。
電(dian)(dian)(dian)(dian)池(chi)剛出廠(chang)時,正負極(ji)之(zhi)間(jian)的(de)電(dian)(dian)(dian)(dian)勢差稱(cheng)為(wei)電(dian)(dian)(dian)(dian)池(chi)的(de)標稱(cheng)電(dian)(dian)(dian)(dian)壓(ya)。標稱(cheng)電(dian)(dian)(dian)(dian)壓(ya)由極(ji)板材料的(de)電(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)位(wei)和(he)內(nei)部電(dian)(dian)(dian)(dian)解液的(de)濃度(du)決定(ding)。當環境溫度(du)、使用時間(jian)和(he)工作(zuo)狀態變(bian)化(hua)時,單元電(dian)(dian)(dian)(dian)池(chi)的(de)輸出電(dian)(dian)(dian)(dian)壓(ya)略(lve)有變(bian)化(hua),此(ci)外,電(dian)(dian)(dian)(dian)池(chi)的(de)輸出電(dian)(dian)(dian)(dian)壓(ya)與(yu)電(dian)(dian)(dian)(dian)池(chi)的(de)剩(sheng)余電(dian)(dian)(dian)(dian)量也有一定(ding)的(de)關系(xi)。單元鎳鎘電(dian)(dian)(dian)(dian)池(chi)的(de)標稱(cheng)電(dian)(dian)(dian)(dian)壓(ya)約為(wei)1.2V(但(dan)一般(ban)認(ren)為是1.25V).
電(dian)池的(de)(de)(de)內阻決(jue)定(ding)于極板的(de)(de)(de)電(dian)阻和離(li)子(zi)(zi)流的(de)(de)(de)阻抗,在充(chong)放(fang)電(dian)過程中(zhong),極板的(de)(de)(de)電(dian)阻是不變(bian)的(de)(de)(de),但是離(li)子(zi)(zi)流的(de)(de)(de)阻抗將隨電(dian)解液濃度(du)的(de)(de)(de)變(bian)化和帶電(dian)離(li)子(zi)(zi)的(de)(de)(de)增(zeng)減而(er)變(bian)化。
電(dian)(dian)(dian)池(chi)(chi)充足電(dian)(dian)(dian)時,極板(ban)上(shang)的活性物質已達到(dao)飽和(he)狀態,再繼(ji)續充電(dian)(dian)(dian), ,電(dian)(dian)(dian)池(chi)(chi)的電(dian)(dian)(dian)壓也不會(hui)上(shang)升,此時的電(dian)(dian)(dian)壓稱為充電(dian)(dian)(dian)終(zhong)止(zhi)電(dian)(dian)(dian)壓。鎳鎘電(dian)(dian)(dian)池(chi)(chi)的充電(dian)(dian)(dian)終(zhong)止(zhi)電(dian)(dian)(dian)壓為1.7 5~1.8V。
放(fang)(fang)電(dian)(dian)(dian)(dian)終(zhong)(zhong)止(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)是(shi)指(zhi)電(dian)(dian)(dian)(dian)池放(fang)(fang)電(dian)(dian)(dian)(dian)時允許的(de)最低電(dian)(dian)(dian)(dian)壓(ya)(ya)。如果電(dian)(dian)(dian)(dian)壓(ya)(ya)低于放(fang)(fang)電(dian)(dian)(dian)(dian)終(zhong)(zhong)止(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)后(hou)電(dian)(dian)(dian)(dian)池繼續放(fang)(fang)電(dian)(dian)(dian)(dian),電(dian)(dian)(dian)(dian)池兩(liang)端電(dian)(dian)(dian)(dian)壓(ya)(ya)會迅速下降,形成深度(du)放(fang)(fang)電(dian)(dian)(dian)(dian),這(zhe)樣極板上形成的(de)生成物在正常充電(dian)(dian)(dian)(dian)時就不易再恢復(fu),從(cong)而影響電(dian)(dian)(dian)(dian)池的(de)壽命(ming)。放(fang)(fang)電(dian)(dian)(dian)(dian)終(zhong)(zhong)止(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和放(fang)(fang)電(dian)(dian)(dian)(dian)率有關。鎳(nie)鎘電(dian)(dian)(dian)(dian)池的(de)放(fang)(fang)電(dian)(dian)(dian)(dian)終(zhong)(zhong)止(zhi)電(dian)(dian)(dian)(dian)壓(ya)(ya)和放(fang)(fang)電(dian)(dian)(dian)(dian)速率的(de)