2.3 退役電池容量衰減突變現(xiàn)象

在隨機(jī)循環(huán)測試的12支退役單體電池中， #1電池在循環(huán)過程中出現(xiàn)容量衰減突變?yōu)? mAh的現(xiàn)象。#1電池的初始放電容量為17.7 Ah，與新電池比，剩余容量為80.5%。在1243次循環(huán)之前，電池充放電容量與循環(huán)次數(shù)出現(xiàn)很好的線性關(guān)系，與#2～#4電池一樣，每發(fā)生一次容量衰減突變，都會(huì)伴隨有較為明顯的容量下降趨勢。在循環(huán)至1243次時(shí)，放電容量突然降至0.12 Ah，與新電池比，剩余容量為0.55%。此后繼續(xù)衰減至接近0 Ah，如圖8所示。

圖6 #4退役單體電池的容量循環(huán)曲線

Fig.6 Capacity fading acteristic for #4 retired power cell in ging/disging condition

圖7 #2～#4退役單體電池的容量衰減率曲線

Fig.7 Capacity fading rates for #2～#4 retired power cells in disging condition

圖8 #1退役單體電池循環(huán)容量衰減曲線

Fig.8 Capacity fading and it’s mutation acteristic for #1 retired power cell in ging/disging condition

#1退役電池的容量衰減率曲線見圖9，在循環(huán)至1242次之前，其衰減率平均為4.4%，且在1242次之前，容量衰減率與循環(huán)次數(shù)間保持較好的線性關(guān)系。循環(huán)至1243次及以后，容量衰減率突然增大近100%。

在本次抽樣實(shí)驗(yàn)研究中，12支單體電池循環(huán)2000次左右后，僅#1電池出現(xiàn)了上述衰減突變現(xiàn)象，發(fā)生概率為8.3%。由此可見，退役電池性能衰減在2000次內(nèi)突變是不可預(yù)測的現(xiàn)象，但存在發(fā)生可能性，且發(fā)生概率不低。這種容量衰減突變現(xiàn)象對(duì)梯次利用儲(chǔ)能系統(tǒng)可靠運(yùn)行是較大的挑戰(zhàn)，一方面需要研究電池容量跳水等性能衰減、突變預(yù)警技術(shù)，另一方面應(yīng)設(shè)計(jì)靈活的儲(chǔ)能系統(tǒng)電氣拓?fù)浣Y(jié)構(gòu)，以便可以隔離突然失效電池所在支路，保證尚未失效支路可以正常工作。

圖9 #1退役單體電池容量衰減率曲線

Fig.9 Capacity fading rate for #1 retired power cell in disging condition

3 結(jié)論

(1)純電動(dòng)大巴和純電動(dòng)出租汽車兩類退役磷酸鐵鋰電池模塊容量測試結(jié)果表明，退役電池模塊間容量差均較為明顯，離散性突出，不利于電池重組。

(2)以退役單體電池為研究對(duì)象，抽樣測試了12支單體電池的循環(huán)性能，2000次充放電循環(huán)試驗(yàn)數(shù)據(jù)表明，絕大多數(shù)退役電池仍具有較好的循環(huán)性能，其容量衰減與循環(huán)次數(shù)呈現(xiàn)明顯的線性關(guān)系，其容量衰減率不超過8%，具有較理想的梯次利用價(jià)值。

(3)退役單體電池2000次充放電循環(huán)試驗(yàn)數(shù)據(jù)表明，個(gè)別退役電池存在容量突變?yōu)榱愕默F(xiàn)象，本文研究抽樣樣本中，其發(fā)生概率為8.3%。為保證退役電池儲(chǔ)能系統(tǒng)可靠性，應(yīng)針對(duì)性開展容量跳水預(yù)警技術(shù)研究。

作者：

趙光金1,2，邱武斌1,2

(1. 國網(wǎng)河南省電力公司電力科學(xué)研究院，河南省 鄭州市 450052;2. 國家電網(wǎng)公司電網(wǎng)廢棄物資源化處理技術(shù)實(shí)驗(yàn)室，河南省 鄭州市 450052)

國家電網(wǎng)公司科技項(xiàng)目(52170217000L)。

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原標(biāo)題:退役磷酸鐵鋰電池容量一致性及衰減特征研究