SECONDARY BATTERIES – LEAD– ACID SYSTEMS | Catalytic Valves

An intrinsic shortcoming of rechargeable electrochemical energy storage systems with aqueous electrolytes is the water loss due to electrolysis. The result of this well-known electrochemical reaction is the formation of oxygen at the positive and hydrogen at the negative electrodes. Because of this effect, lead–acid batteries in standby operation or at charging show an increase in the rate of water loss and a higher detonation hazard depending on the hydrogen concentration. To overcome these drawbacks, catalyst plugs were introduced to recombine the released oxyhydrogen gas mix with the formed water returning to the cell. The deployment of these devices, mounted on the top of the cells, extends significantly the topping-up intervals and minimizes the danger of explosion. In recent years the application field for external catalyst plugs in conventional vented batteries was extended to valve-regulated lead–acid batteries, resulting in a new generation of internal recombinators in the form of small catalyst plugs mounted inside the cells.