Patent ID: 8691060

Claim:
A water electrolysis apparatus comprising: an electrolyte membrane; a pair of circular current collectors disposed respectively on opposite sides of the electrolyte membrane; a pair of separators stacked respectively on the circular current collectors; wherein a water flow field for supplying water is defined between one of the circular current collectors and one of the separators and a hydrogen flow field for producing hydrogen through electrolysis of the water is defined between the other circular current collector and the other separator; a water supply passage extending along a stacked direction in which the separators are stacked, for supplying the water to the water flow field; and a discharge passage extending along the stacked direction, for discharging a remaining amount of the water from the water flow field; wherein the water flow field includes: a plurality of water channels extending along a plane of the circular current collector across an imaginary straight line which interconnects the water supply passage and the discharge passage, and disposed parallel to each other in the plane of the circular current collector; an arcuate inlet buffer extending around the circular current collector and held in fluid communication with the water supply passage; and a plurality of inlet joint channels interconnecting the water channels and the arcuate inlet buffer; wherein the inlet joint channels are oriented at an angle of 90 degrees or greater with respect to respective tangential lines at the ends of the inlet joint channels which are connected to the arcuate inlet buffer.