MH-Ni电池安全性能的研究

Study on the safety performance of Ni-MH batteries

AA型MH-Ni电池在充电过程中电池内压及电池外壁温度随充入电量的增加会经历较低水平、迅速增高和进入平台三个阶段的变化,而且充电倍率越大,电池内压及外壁温度的平台越高,实验数据表明1 C5以下的过充电不影响电池的安全性。做MH-Ni电池短路实验,并对电池内部气体进行定性与定量分析,找出电池爆炸的原因为电池短路后产生大量的热,致使电池内部温度和气压上升,造成负极贮氢合金粉在高温高压环境下析出H2、隔膜炭化放出气体、电池内部短路放热等一系列连锁反应,导致电池内压剧增。电池爆炸时的最大压力一般达到5.5 MPa左右,最高温度一般达到190～200 ℃。

In the charging process of AA type Ni-MH battery, the internal pressure and the temperature of battery outside wall will experience three stages: the lower level, quick increase and become platform, following the increasing of charge capacity. The charge multiplying power is more large, the platform of the internal pressure and the temperature of battery outside wall is more high. The experiment data express overcharge below the 1 C5 doesn't affect the security of batteries. Through the Ni-MH battery short circuit experiments, the qualitative and quantitative analysis to the internal gas in battery, the reasons of the battery explosion were found out: A flood of heat that produced by short circuit of batteries caused the increase of temperature and internal pressure, then storage hydrogen alloy separated out H2, separator burned, and internal short circuit happened. At last, the internal pressure of battery increased intensively and battery was explosive. The highest pressure of battery explosion attains about 5.5 MPa, and the highest temperature attains 190-200 ℃.