锂电池充放电电路-锂电池过充、过放电的影响及控制方法

锂电池

“锂(li)电(dian)池(chi)”，是一类由锂(li)金(jin)属(shu)或锂(li)合金(jin)为(wei)负极材料、使(shi)用(yong)非水电(dian)解质溶液的电(dian)池(chi)。1912年(nian)锂(li)金(jin)属(shu)电(dian)池(chi)最(zui)早由Gilbert N. Lewis提出并研究。20世(shi)纪70年(nian)代时，M. S. Whittingham提出并开始研究锂(li)离子(zi)电(dian)池(chi)。由于锂(li)金(jin)属(shu)的化学特性非常活(huo)泼，使(shi)得锂(li)金(jin)属(shu)的加(jia)工、保存、使(shi)用(yong)，对环(huan)境要求非常高。

锂电池充放电电路要求

锂电池(chi)充放电电路(lu)要求如(ru)下(xia)：

1、锂电(dian)(dian)池(chi)的充(chong)电(dian)(dian)

根(gen)据锂电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)结构特性，最高(gao)(gao)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)终止(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)应为4.2V，不能过充(chong)，否则会因正(zheng)极的(de)锂离子拿走太多，而使电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池报废(fei)。其充(chong)放(fang)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)要求较(jiao)高(gao)(gao)，可(ke)采用专用的(de)恒流(liu)、恒压(ya)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)器进行充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)。通常恒流(liu)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)至 4.2V/节后转入恒压(ya)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)，当恒压(ya)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)降至 100mA 以内时，应停止(zhi)充(chong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)。

充(chong)(chong)电电流（mA）=0.1～1.5倍电池(chi)容量（如1350mAh的电池(chi)，其充(chong)(chong)电电流可控制在135～2025mA之间）。常规充(chong)(chong)电电流可选择在0.5倍电池(chi)容量左右(you)，充(chong)(chong)电时间约为2～3小时。

2、锂电池的放电

因锂(li)电(dian)池(chi)的内部(bu)结构所(suo)致，放电(dian)时锂(li)离(li)子不(bu)能全(quan)部(bu)移向正极，必须保留一部(bu)分锂(li)离(li)子在负(fu)极，以(yi)保证在下次充电(dian)时锂(li)离(li)子能够畅通(tong)地嵌入通(tong)道。否则，电(dian)池(chi)寿命(ming)就相应缩短。

为了保证石墨层(ceng)中放(fang)电(dian)(dian)(dian)(dian)后留有(you)部(bu)分锂(li)离子，就要严(yan)格(ge)(ge)限制放(fang)电(dian)(dian)(dian)(dian)终(zhong)止(zhi)最(zui)低电(dian)(dian)(dian)(dian)压，也就是(shi)说锂(li)电(dian)(dian)(dian)(dian)池(chi)(chi)不能(neng)过放(fang)电(dian)(dian)(dian)(dian)。放(fang)电(dian)(dian)(dian)(dian)终(zhong)止(zhi)电(dian)(dian)(dian)(dian)压通常为3.0V/节(jie)，最(zui)低不能(neng)低于(yu)2.5V/节(jie)。电(dian)(dian)(dian)(dian)池(chi)(chi)放(fang)电(dian)(dian)(dian)(dian)时间(jian)长短(duan)与电(dian)(dian)(dian)(dian)池(chi)(chi)容量(liang)、放(fang)电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)大(da)小(xiao)有(you)关。电(dian)(dian)(dian)(dian)池(chi)(chi)放(fang)电(dian)(dian)(dian)(dian)时间(jian)（小(xiao)时）=电(dian)(dian)(dian)(dian)池(chi)(chi)容量(liang)/放(fang)电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)。锂(li)电(dian)(dian)(dian)(dian)池(chi)(chi)放(fang)电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(mA)不应超过电(dian)(dian)(dian)(dian)池(chi)(chi)容量(liang)的 3 倍(bei)。（如 1000mAH 电(dian)(dian)(dian)(dian)池(chi)(chi)，则(ze)放(fang)电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)应严(yan)格(ge)(ge)控制在3A以内）否则(ze)会使电(dian)(dian)(dian)(dian)池(chi)(chi)损(sun)坏。

锂电池的保护电路

两(liang)节锂电池的(de)充放电保护电路如下图所示：

由两个场(chang)效(xiao)应管和专(zhuan)用保护(hu)(hu)集成块S--8232 组成，过充(chong)电(dian)(dian)(dian)(dian)控(kong)制管 FET2 和过放电(dian)(dian)(dian)(dian)控(kong)制管 FET1串联于(yu)电(dian)(dian)(dian)(dian)路，由保护(hu)(hu)IC监视电(dian)(dian)(dian)(dian)池(chi)电(dian)(dian)(dian)(dian)压(ya)并进行控(kong)制，当(dang)电(dian)(dian)(dian)(dian)池(chi)电(dian)(dian)(dian)(dian)压(ya)上升至(zhi)4.2V时(shi)，过充(chong)电(dian)(dian)(dian)(dian)保护(hu)(hu)管FET1截(jie)止(zhi)，停止(zhi)充(chong)电(dian)(dian)(dian)(dian)。为(wei)防止(zhi)误动作，一般(ban)在外电(dian)(dian)(dian)(dian)路加有延时(shi)电(dian)(dian)(dian)(dian)容。

锂电池充放电电路-过充、过放电的影响及控制方法

（一）过充电

1、什么是过充电，对电池性能有何影响?

过(guo)(guo)充(chong)(chong)电(dian)是指电(dian)池经一(yi)定充(chong)(chong)电(dian)过(guo)(guo)程充(chong)(chong)满电(dian)后，再继(ji)续充(chong)(chong)电(dian)的行为。由于在设计时(shi)，负(fu)极(ji)容量(liang)比正极(ji)容量(liang)要高，因此，正极(ji)产(chan)生的气体(ti)透过(guo)(guo)隔膜纸与负(fu)极(ji)产(chan)生的镉复合。故一(yi)般情况下，电(dian)池的内压不会(hui)有明显(xian)升高，但如果充(chong)(chong)电(dian)电(dian)流过(guo)(guo)大，或充(chong)(chong)电(dian)时(shi)间过(guo)(guo)长，产(chan)生的氧气来不及被消耗，就可能造(zao)成(cheng)内压升高，电(dian)池变形，漏液，等不良现(xian)象。同时(shi)，其电(dian)性(xing)能也会(hui)显(xian)着降(jiang)低。

2、过充电的控制方法有哪些?

为了防(fang)止电池(chi)过(guo)充(chong)，需要对充(chong)电终点进(jin)行控制，当电池(chi)充(chong)满(man)时(shi)，会有(you)一些特别(bie)的信息可利(li)用来(lai)判断充(chong)电是(shi)否达到终点。一般(ban)有(you)以(yi)下六种方法来(lai)防(fang)止电池(chi)被过(guo)充(chong)：

1. 峰值电(dian)压控(kong)制:通(tong)过检(jian)测电(dian)池(chi)的峰值电(dian)压来判断充电(dian)的终(zhong)点(dian);

2. dT/dt控制:通过(guo)检测电池(chi)峰值温度变(bian)化率来判断充电的(de)终(zhong)点;

3. T控制:电池充满电时温度与环境温度之(zhi)差会达(da)到最大;

4. -V控制:当(dang)电(dian)池充满电(dian)达到(dao)一峰值电(dian)压后,电(dian)压会下降一定的值

5. 计时(shi)控(kong)制(zhi):通(tong)过(guo)设置一定的充电(dian)时(shi)间(jian)(jian)来(lai)控(kong)制(zhi)充电(dian)终点,一般设定要充进130%标称(cheng)容量所需的时(shi)间(jian)(jian)来(lai)控(kong)制(zhi);

6. TCO控制(zhi):考虑(lv)电(dian)池(chi)的安全和特(te)性应(ying)(ying)当(dang)避(bi)免高(gao)温(wen)(高(gao)温(wen)电(dian)池(chi)除外)充电(dian),因此(ci)当(dang)电(dian)池(chi)温(wen)度升(sheng)高(gao)60时应(ying)(ying)当(dang)停止充电(dian)。

（二）过放电

1、什么是过放电，对电池性能有何影响?

电(dian)(dian)(dian)(dian)(dian)池(chi)放(fang)(fang)完内部(bu)储存的电(dian)(dian)(dian)(dian)(dian)量(liang)，电(dian)(dian)(dian)(dian)(dian)压(ya)达到一定值(zhi)后，继续放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)就(jiu)会(hui)造(zao)成过(guo)(guo)放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)，通常根据放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)流来确定放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)截止电(dian)(dian)(dian)(dian)(dian)压(ya)。0.2C-2C放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)一般设定1.0V/支,3C 以上如5C或(huo)10C放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)设定为(wei)0.8V/支,电(dian)(dian)(dian)(dian)(dian)池(chi)过(guo)(guo)放(fang)(fang)可(ke)能会(hui)给(ji)电(dian)(dian)(dian)(dian)(dian)池(chi)带(dai)来灾难性的后果,特别(bie)是(shi)大电(dian)(dian)(dian)(dian)(dian)流过(guo)(guo)放(fang)(fang)，或(huo)反复过(guo)(guo)放(fang)(fang)对电(dian)(dian)(dian)(dian)(dian)池(chi)影响更(geng)大。一般而言，过(guo)(guo)放(fang)(fang)电(dian)(dian)(dian)(dian)(dian)会(hui)使电(dian)(dian)(dian)(dian)(dian)池(chi)内压(ya)升高，正负极(ji)活性物质(zhi)可(ke)逆性受到破坏(huai)，即使充电(dian)(dian)(dian)(dian)(dian)也只能部(bu)分恢复，容量(liang)也会(hui)有(you)明显衰减。

2、正确放电方法

及时充电(dian)(dian)，防过放(fang)(fang)。普通(tong)的(de)(de)锂电(dian)(dian)池(chi)使(shi)用(yong)者对于(yu)过放(fang)(fang)的(de)(de)危害(hai)(hai)没(mei)有意识，因(yin)为(wei)通(tong)常(chang)过放(fang)(fang)没(mei)有出现过安全(quan)事故的(de)(de)报道。而且(qie)，有人甚至认为(wei)定期的(de)(de)深度放(fang)(fang)电(dian)(dian)对于(yu)电(dian)(dian)池(chi)性能的(de)(de)维护有好(hao)(hao)处。实则不(bu)然，因(yin)为(wei)锂电(dian)(dian)池(chi)的(de)(de)记忆(yi)效应可以忽略不(bu)计(ji)，不(bu)存在深度放(fang)(fang)电(dian)(dian)消除记忆(yi)效应的(de)(de)说法。理论上来说，锂电(dian)(dian)池(chi)深度放(fang)(fang)电(dian)(dian)总的(de)(de)循(xun)环(huan)寿命会更大(da)些，但其风险是电(dian)(dian)池(chi)过度放(fang)(fang)电(dian)(dian)将导致(zhi)电(dian)(dian)池(chi)电(dian)(dian)压过低，不(bu)能正常(chang)充电(dian)(dian)。两害(hai)(hai)相权取其轻，使(shi)用(yong)寿命短一点总比不(bu)能使(shi)用(yong)好(hao)(hao)。

锂电池的特点

1、具(ju)有(you)更高的(de)重(zhong)量能量比(bi)、体积能量比(bi)；

2、电(dian)(dian)(dian)(dian)压(ya)高(gao)，单节锂(li)电(dian)(dian)(dian)(dian)池(chi)电(dian)(dian)(dian)(dian)压(ya)为3.6V等于3只镍(nie)镉或镍(nie)氢充电(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)池(chi)的串联电(dian)(dian)(dian)(dian)压(ya)；

3、自(zi)放(fang)电小可长时间存放(fang)，这是(shi)该电池最突出的(de)优越性；

4、无记(ji)忆效(xiao)应(ying)。锂电(dian)(dian)池(chi)不存在镍镉电(dian)(dian)池(chi)的所(suo)谓记(ji)忆效(xiao)应(ying)，所(suo)以锂电(dian)(dian)池(chi)充电(dian)(dian)前(qian)无需放电(dian)(dian)；

5、寿(shou)命长。正(zheng)常(chang)工作(zuo)条(tiao)件下(xia)，锂(li)电池充(chong)/放电循环次(ci)数远大于500次(ci)；

6、可(ke)以(yi)快速充电(dian)。锂(li)电(dian)池通常(chang)可(ke)以(yi)采用0.51倍容(rong)量的电(dian)流充电(dian)，使充电(dian)时间缩短至12小时；

7、可以(yi)随(sui)意并联使用；

8、由于电(dian)池(chi)(chi)中不(bu)含(han)镉、铅、汞等重金属元素，对环境无(wu)污染，当代最先(xian)进(jin)的绿色电(dian)池(chi)(chi)；

9、本(ben)钱高(gao)。与其它可充电池相比，锂(li)电池价(jia)格较贵(gui)。

联系方式(shi)：邹先生

联系电(dian)话：0755-83888366-8022

手机：18123972950

QQ：2880195519

联系(xi)地址：深圳市福田区车公庙天(tian)安(an)数码城天(tian)吉大厦CD座5C1

请搜(sou)微(wei)信公(gong)众号:“KIA半(ban)导体”或(huo)扫一(yi)扫下(xia)图“关注”官方(fang)微(wei)信公(gong)众号

请“关(guan)注”官方微(wei)信公众号:提供 MOS管 技(ji)术帮助