Low-cost and energy-efficient asymmetric nickel electrode for alkaline water electrolysis

Porous nickel electrodes for alkaline water electrolysis were made in simple manner by sintering nickel powder that was first compressed into nickel foam. The pores inside the sintered body show asymmetrical distribution in size, small pores (∼5 μm) existing near one surface and open structure (pore size: 100-200 μm) at the other surface. Such asymmetric body performs the dual role such that one surface has the electro-catalytic layer for the electrochemical reactions and the other surface has the escaping route of gas/electrolyte mixture. A nickel electrode stack was assembled by incorporating the sintered bodies, polymer separators and multi-functional light-weight gaskets. Two nickel electrodes with a separator between them were enclosed to make a unit cell in the gasket frame which plays the multi-role of electrolyte supply, exit of produced gas and sealing agent. By applying 1.8 V per unit cell, an electrolyzer made of such stacks with electrodes of 200 cm2 surface area displays current of over 80 A at 80 °C over 400 h.