Method and apparatus for adding electrolyte to a fuel cell stack

Claim 1

In a process for adding electrolyte to a fuel cell stack, said stack comprising a plurality of sheet-like elements defining a plurality of fuel cell units disposed one atop the other in abutting relationship, said units defining a substantially flat, vertically extending external face, each unit including a cell comprising a pair of sheet-like spaced apart gas porous electrodes with a porous matrix layer sandwiched therebetween for retaining electrolyte during cell operation, each unit also including a sheet-like substantially non-porous separator, said separator being sandwiched between the cells of adjacent units, the improvement comprising: extending at least one of said sheet-like elements of each of a plurality of said fuel cell units outwardly from said stack face to define a plurality of horizontal tabs disposed one above the other; depositing dilute electrolyte directly from electrolyte supply means upon substantially the full length, parallel to said stack face, of at least the uppermost tab, said tabs being constructed and arranged such that at least a portion of the deposited electrolyte cascades from tab to tab and down the said face of said stack, said deposited electrolyte being absorbed by capillary action into the elements of said stack, said step of depositing continuing until all of said electrodes and matrix layers of said stack are fully saturated with the dilute electrolyte; and thereafter evaporating liquid from said saturated elements under controlled conditions of humidity and temperature until said stack has a desired electrolyte volume and electrolyte concentration therein.