Oxygen and hydrogen gas recombination in NiMH cells

► Gas recombinations in NiMH cells are directly evaluated by a new technique. ► These were studied as function of gas pressure, temperature and state of charge. ► A linear dependence of the gas pressure indicates that surface reactions are important. ► Oxygen recombination was found to be 10 times quicker than for hydrogen. ► Arrhenius activation energy constants for oxygen and hydrogen could be determined.