Lead acid-NiMH hybrid battery system using gel electrolyte

Abstract

Due to its mature technological status, lead acid batteries have not been the focal point of batteries in the last decade. With the limitation on other new battery types – such as low power density for lithium ion battery, high self discharge and short life cycles for high current discharge for nickel metal hydride (Ni-MH) battery – researchers has revisited the possibilities to enhance lead acid battery technology. Lead acid batteries are durable with low maintenance, inexpensive and simple to manufacture; recyclable and lowest self discharge among other rechargeable systems. With the above advantages, lead acid batteries are both cost effective and energy efficient; it is expected that lead acid battery would attract interests from battery manufacturers should the lower energy density and cycle life be improved. Here, we report the use of a hybrid system composed of lead acid and nickel metal hydride batteries, with the positive PbO2 electrode and negative MH electrode suspended in H2SO4 and KOH gel electrolyte. The lead acid and NiMH sections are separated by the anion exchange membrane and cation exchange membrane respectively, with a neutral K2SO4 solution (in the centre) sandwiched between the two membranes. It is anticipated that the construct of this hybrid cell would compromise the respective limitations of the individual lead acid or Ni-MH batteries. The hybrid system in gel electrolyte is able to maintain its capacity longer than that of the aqueous electrolyte. Moreover, the hybrid system in gel electrolyte also solves the safety issues concerning the transportation restrictions on flooded lead acid battery …