Study Of Ni-MH Batteries For Hybride Electric Vehicle

The main research work of this paper was illustrated as follows: Firstly, according to the request that controlling aspect of the Ni/ MH motive battery used for HEV, the relationship between inner pressure and state of charge of Ni/MH battery was studied. Secondly, the square Ni/ MH batteries with the capacity of the 5.7 Ah were studied and prepared, and the comprehensive performance test was carried on. Thirdly, several different materials were researched on the influence and function mechanism for carrying on the surface processing and self-discharge of the batteries as the cathode additive.Under certain ratio of positive capacity to negative capacity, the inner pressure presented linear relation to SOC after 30 cycles. Based on this conclusion, the inner pressure can be a parameter or behavior the SOC of Ni/MH directly. Under certain SOC, the inner pressure will increase non-linearly with the increase of the ratio of positive capacity to negative capacity. The inner pressure will not exceed 0.2MPa until the ratio of positive capacity to negative capacity reach 1:1.00 and the SOC range from 30% to 80%. Despite the change of inner pressure during the charge period, the inner pressure will present the same function to the SOC after enough displaying time. The inner pressure during charge period and discharge period will rise suddenly with the increasing of temperature. Based on above analysis, it can be concluded that the inner pressure can be used to determine the SOC of Ni/ MH battery in HEV.By testing the battery resistance, we chose the dimension of the square Ni/MH battery of the 5.7Ah capacity as follow: the size of positive was 120mm×72mm,and the size of negative was 121mm×72mm, which presented the low resistance. At room temperature, the experimental shows that, the square Ni/MH battery of the 5.7Ah met the capacity request of"863", and the power density achieved the local average level. At the same time, the experience of hot processing of MH alloy shows that, the key factor determine the oxidation of alloy were the amount of hydrogen during hot processing and the cool state when the alloy come out of the hydrogen atmosphere.The research based on self-designed experiment device shows that the...