What are the problems caused by the current fluctuation of alkaline electrolyzer?

What are the problems caused by the current fluctuation of

alkaline electrolyzer? The amount of gas produced by an

alkaline electrolyzer is closely related to the current. According to Faraday's law, the amount of matter produced by electrolysis is proportional to the amount of electricity passed (the product of current and time). Therefore, when the current drops momentarily, the production of hydrogen and oxygen at the cathode and anode decreases proportionally. Due to the phenomenon of gas leakage between the cathode and anode inside the electrolytic cell, the function of the diaphragm is to minimize this gas leakage, but there will still be some leakage. When the gas production decreases, the relative concentration of gas after gas leakage will increase. When operating at very low current, the concentration of hydrogen in oxygen may reach the minimum explosion limit of 4%, which is a very serious safety hazard. When the

electrolytic cell works, it will produce heat, which is related to the current. When the current drops, so does the amount of heat produced. However, the cooling system is not able to respond quickly to this change in heat, causing the temperature of the cell to drop. The rate of electrode reaction is usually related to temperature. With the decrease of temperature, the velocity of reaction molecules slows down and the effective collision decreases, which leads to the decrease of electrolysis efficiency.

When the current rises instantaneously, the production of hydrogen and oxygen at the cathode and anode increases. A large number of bubbles will be produced on the surface of the electrode, which are easy to cover the catalytic active sites of the electrode, hinder the contact between reactants and catalysts, and increase the resistance of catalytic reaction. According to Nernst equation and Tafel equation, when the reaction resistance increases, the overpotential will rise, which shows that the cell voltage of the electrolytic cell increases.

Meanwhile, when the current rises, the supply of the electrolyte to the electrode surface is delayed. This is because the supply speed of the electrolyte may not keep up with the sudden increase in the reaction speed, and there is a certain hysteresis. As a result, the reaction on the surface of a large area of electrode is uneven, and the reaction in some areas is too fast, resulting in local hot spots. These local hot spots may damage the electrode material or diaphragm, affecting the life and performance of the cell.