Abstract: During recharge of a lead-acid battery, initially evolves oxygen gas and later hydrogen gas. These characteristics are favorable for a sealed lead-acid battery with oxygen recombination reaction.
Oxygen-recombination chemistry has been wedded to traditional lead-acid battery technology to produce so-called sealed, or valve-regulated, lead-acid products. Early attempts to incorporate recombination into lead-acid batteries were unsuccessful because of excessive cost, size, and/or complexity, and none were effectively commercialized.
A recombination battery is a type of battery where the process of charging reverses the chemical reaction that occurs during discharge, allowing the oxygen and hydrogen gases produced to react and form water, reducing the need for maintenance. Recombination batteries were first used in aircraft applications in the late 1970s in the U.S.A., where individual cylindrical cells (with a C/1 capacity of 18 A h) were assembled in a rectangular outer case to give a 24 V battery.
Instead, the focus is on the gas recombination chemistry and some of the ways battery technologists must deal with it in developing functional VRLA products. Sealed nickel-cadmium cell technology has been developed to optimize the efficiency of the oxygen-recombination process.
The operating voltage of a recombination battery is higher than that of an equivalent battery with flooded electrolyte.\n\nA recombination battery is capable of giving 8 - 8.5 hours at a discharge current of 150 A (6 C/1) at ambient temperature.
Oxygen formation is initiated at the nickel electrode/electrolyte interface. Small gas bubbles are formed and the gas will be transported to the gas phase. Recombination starts by redissolution of oxygen in the electrolyte and will subsequently be reduced at the MH electrode/electrolyte interface.