The effects of pulse charging on inner pressure and cycling characteristics of sealed Ni/MH batteries

• Published in: Journal of power sources Vol. 136; no. 1; pp. 180 - 185
• Main Authors: Zhang, Jixiao, Yu, Jingxian, Cha, Chuansin, Yang, Hanxi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10.09.2004; Elsevier Sequoia
• Subjects: Applied sciences; Cycling characteristics; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Inner pressure; Pulse charging; Sealed Ni/MH cell; Sealed Ni/MH cell; Inner pressure; Cycling characteristics; Pulse charging; Scanning electron microscopy; Anode; Secondary cell; Discharge charge cycle; Battery; Slowing down; Nickel; Comparative study; Fuel cell; Electrochemical impedance spectroscopy
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2004.05.008

The effects of pulse charging technique on inner pressure and cycling characteristics of sealed Ni/MH batteries were investigated by comparison with the conventional direct current (DC) charging. The electrochemical impedance spectroscopy of cycled Ni/MH batteries have been measured. The micrographs of individual electrodes in the batteries have also been examined by SEM. Experimental results show that pulse charging is an effective approach to lower the internal pressure of battery during charge and overcharge, moreover, the appropriate frequency is t p = 5 s and t n = 1 s in our experiments. The battery charged by pulse current exhibits slower capacity fade rate and smaller overpotential at the same charge–discharge rate. In addition, the anode charged by pulse current exhibits less serious pulverization than that charged by DC charging. The possible explanation is that the short relaxation periods interspersed during the charging process can effectively eliminate the concentration polarization and increase the power transfer rate, thus accelerating the charging process, reducing the gas evolution reaction, slowing down the pulverization rate of electroactive materials and keeping the water absorption capability of separator constant.