Electrochemical system with confined electrolyte

Abstract

Described herein are systems and methods for the management and control of electrolyte within confined electrochemical cells or groups (e.g. stacks) of connected electrochemical cells, for example, in an electrolyzer. Various embodiments of systems and methods provide for the elimination of parasitic conductive paths between cells, and/or precise passive control of fluid pressures within cells. In some embodiments, a fixed volume of electrolyte is substantially retained within each cell while efficiently collecting and removing produced gases or other products from the cell.

1 - 57 . (canceled) 
     
     
         58 . An electrochemical system, comprising:
 a stack of electrochemical cells, each individual electrochemical cell independently comprising:
 a first half-cell chamber containing a first electrode and containing a volume of fluid fluctuating between a first fluid pressure and a second fluid pressure; 
 a second half-cell chamber containing a second electrode; 
 a separator separating the first half-cell chamber from the second half-cell chamber; and 
 a make-up liquid inlet comprising a one-way valve arranged to provide flow of make-up liquid into the first half-cell chamber and to prevent flow of liquid out of the half-cell through the make-up liquid inlet; 
   a make-up liquid supply manifold in fluid communication with the make-up liquid inlet of all cells of the stack, the make-up liquid supply manifold containing a make-up liquid at a third fluid pressure, the third fluid pressure is a controlled pressure that is greater than the first pressure and less than the second pressure.   
     
     
         59 . The electrochemical system of  claim 58 , further comprising a first gas-removal manifold in fluid communication with the first half-cell chamber, the first gas-removal manifold containing a first gas-removal liquid flowing therethrough and maintained at a controlled fourth pressure that is less than the first pressure. 
     
     
         60 . The electrochemical system of  claim 59 , further comprising a second gas-removal manifold in fluid communication with the second half-cell chamber, the second gas-removal manifold containing a second gas-removal liquid flowing therethrough and maintained at a controlled fifth pressure that is equal to the fourth pressure. 
     
     
         61 . The electrochemical system of  claim 60 , further comprising a first fluid escape element between the first half-cell chamber and the first gas-removal manifold, wherein the first fluid escape element imparts a resistance to flow of gas which dampens pressure oscillations between the first half-cell chamber and the first gas-removal manifold. 
     
     
         62 . The electrochemical system of  claim 61 , further comprising a second fluid escape element between the second half-cell chamber and the second gas-removal manifold, wherein the second fluid escape element imparts a resistance to flow of gas which dampens pressure oscillations between the second half-cell chamber and the second gas-removal manifold. 
     
     
         63 . The electrochemical system of  claim 62 , wherein the first fluid escape element or the second fluid escape element is a series fluid escape element. 
     
     
         64 . The electrochemical system of  claim 63 , wherein the series fluid escape element is an egress channel with a total interior fluid path length that is at least 10 times greater than an interior cross-sectional area. 
     
     
         65 . The electrochemical system of  claim 63 , wherein the series fluid escape element is an egress channel with a tortuous path. 
     
     
         66 . The electrochemical system of  claim 63 , wherein the series fluid escape element is an egress channel with a mechanically restricted conduit. 
     
     
         67 . The electrochemical system of  claim 63 , wherein incompressible liquid and compressible gas flow through the series fluid escape element as discrete liquid pockets of and gas pockets, wherein the liquid pockets experience flow resistance due to surface tension with an interior wall of the fluid escape element. 
     
     
         68 . A method of operating an electrochemical system; wherein the electrochemical system comprises:
 a stack of electrochemical cells, each individual electrochemical cell independently comprising:
 a first half-cell chamber containing a first electrode and containing a volume of fluid fluctuating between a first fluid pressure and a second fluid pressure; 
 a second half-cell chamber containing a second electrode; 
 a separator separating the first half-cell chamber from the second half-cell chamber; and 
 a make-up liquid inlet comprising a one-way valve; and 
   a make-up liquid supply manifold in fluid communication with the make-up liquid inlet of all cells of the stack, the make-up liquid supply manifold containing a make-up liquid at a third fluid pressure; and   the method comprising steps of:   providing, via the one-way valve, a flow of make-up liquid into the first half-cell chamber;   preventing, via the one-way vale, a flow of liquid out of the half-cell through the make-up liquid inlet; and   controlling the third fluid pressure such that it is greater than the first pressure and less than the second pressure.   
     
     
         69 . The method of  claim 68 , further comprising removing a liquid-gas mixture from the first half-cell chamber, separating the mixture into first liquid and first gas, and returning the first liquid to the half-cell without mixing the liquid with liquid from any other cell in the stack. 
     
     
         70 . The method of  claim 69 , further comprising removing the first gas via a first gas-removal manifold common to all cells in the stack, and controlling a fluid pressure in the first gas-removal manifold at a fourth pressure that is less than the first pressure. 
     
     
         71 . The method of  claim 70 , further comprising dampening pressure oscillations between the first half-cell chamber and the first gas-removal manifold. 
     
     
         72 . The method of  claim 70 , further comprising removing a second gas from the second half-cell chamber via a second gas-removal manifold common to all cells in the stack, and controlling a fluid pressure in the second gas-removal manifold at a fifth pressure that is equal to the fourth pressure. 
     
     
         73 . The method of  claim 72 , further comprising dampening pressure oscillations between the second half-cell chamber and the second gas-removal manifold. 
     
     
         74 . The electrochemical system of  claim 58 , wherein an electrolyte in each individual electrochemical cell of the stack is fluidically isolated from an electrolyte in each other individual electrochemical cell of the stack. 
     
     
         75 . The electrochemical system of  claim 58 , wherein the volume of fluid is a mixture of gas and liquid. 
     
     
         76 . The electrochemical system of  claim 58 , wherein third fluid pressure is within 0.5±0.2 bar of an average steady-state operating pressure of the volume of fluid in the first half-cell chamber. 
     
     
         77 . The electrochemical system of  claim 58 , wherein the second half-cell chamber further comprises a second volume of liquid. 
     
     
         78 . The electrochemical system of  claim 68 , wherein an electrolyte in each individual electrochemical cell of the stack is fluidically isolated from an electrolyte in each other individual electrochemical cell of the stack. 
     
     
         79 . The electrochemical system of  claim 68 , wherein third fluid pressure is within 0.5±0.2 bar of an average steady-state operating pressure of the volume of fluid in the first half-cell chamber. 
     
     
         80 . The electrochemical system of  claim 68 , wherein the second half-cell chamber further comprises a second volume of liquid.