How does hydrogen evolution affect battery performance?

Hydrogen evolution impacts battery performance as a secondary and side reaction in Lead–acid batteries. It influences the volume, composition, and concentration of the electrolyte. Generally accepted hydrogen evolution reaction (HER) mechanisms in acid solutions are as follows:

Can hydrogen evolve on lead–carbon batteries?

The main challenging issues of hydrogen evolution on lead–carbon batteries are discussed in different ways and perspective views to higher performance on future energy storage applications have also been presented.

How is hydrogen gas inhibition effected in a lead–acid battery?

The hydrogen gas inhibition is effected by an organic inhibitor (L-serine) adsorbed through electrostatic attractive forces between functional groups on the metal surface in the negative electrode of lead–acid battery [ 117 ].

Why is hydrogen evolution a problem in a hybrid battery system?

The ultra-battery usually contains activated carbon materials in the negative electrode. The activated carbon can initiate hydrogen evolution at a low overpotential in sulfuric acid electrolyte [ 120 ]. Therefore, hydrogen evolution is a challenging issue in the hybrid battery system when using Pb/C as the negative electrode.

Why do lead acid batteries outgass?

This hydrogen evolution, or outgassing, is primarily the result of lead acid batteries under charge, where typically the charge current is greater than that required to maintain a 100% state of charge due to the normal chemical inefficiencies of the electrolyte and the internal resistance of the cells.

What happens if a lead-acid battery is charged with a carbon electrode?

Under the cathodic working conditions of a Lead–acid battery (−0.86 to −1.36 V vs. Hg/Hg 2 SO 4, 5 mol/L sulfuric acid), a carbon electrode can easily cause severe hydrogen evolution at the end of charge. This can result in thermal runaway or even electrolyte dry out, as shown in Fig. 5.