Development of High
Development of High Performance Nickel-Metal Hydride Batteries forHybrid Electric Vehicles
HEV(hybrid electric vehicle) batteries require higher currentoutput than the batteries for general consumer use. A maximumoutput requirement is generally 100 A -150A. With our accumulated technologies, we have developed anickel-metal hydride (Ni-MH) battery (D-size model: HR-DP) whichmeets the requirement of higher output. We announced our newbattery at the 33 rd Tokyo Motor Show 1999. With the use of a lowerresistance collector, battery has been improved which enabled us tolower the internal resistance. We have succeeded in assuring acurrent output 2.5 times as much as that of the consumer-use D-sizebattery. The optimization of the positive electrode has alsoimproved charging characteristics at a high temperature and theimprovement of the hydrogen absorbing alloy has improved cyclelife. The ISG (Integrated Starter Generator) requires highercurrent than the HEV use, where a maximum requirement isfrom 300A to 500A. To meet with these high current requirements, we are currentlyunder the development of M-size battery (model: HR-MP). In thispaper, we discuss various improvements of the characteristics ofthe Ni-MH battery (HR-DP) for the HEV use, with more emphasis onoutput improvement, high temperature charging efficiency andprolonged cycle life. Some aspects of the Ni-MH battery (HR-MP) forthe ISG use are also discussed.