Release system for electrochemical cells

Abstract

Electrochemical cells, and more specifically, release systems for the fabrication of electrochemical cells are described. In particular, release layer arrangements, assemblies, methods and compositions that facilitate the fabrication of electrochemical cell components, such as electrodes, are presented. In some embodiments, methods of fabricating an electrode involve the use of a release layer to separate portions of the electrode from a carrier substrate on which the electrode was fabricated. For example, an intermediate electrode assembly may include, in sequence, an electroactive material layer, a current collector layer, a release layer, and a carrier substrate. The carrier substrate can facilitate handling of the electrode during fabrication and/or assembly, but may be released from the electrode prior to commercial use.

1 . An electrode, comprising:
 a current collector;   an electroactive material layer; and   a release layer, wherein the current collector is positioned between the electroactive layer and the release layer.   
     
     
         2 . An electrode as in  claim 1 , wherein the current collector is positioned adjacent the release layer, and the electroactive material layer is positioned adjacent the current collector. 
     
     
         3 . An electrode as in  claim 1 , wherein the release layer comprises a polymeric material. 
     
     
         4 . An electrode as in  claim 1 , wherein the release layer comprises a polymeric material having hydroxyl functional groups. 
     
     
         5 . An electrode as in  claim 1 , wherein the release layer comprises poly(vinyl alcohol). 
     
     
         6 . An electrode as in  claim 1 , wherein the release layer has a thickness of about 10 microns or less. 
     
     
         7 . An electrode as in  claim 1 , wherein the release layer has a thickness of about 3 microns or less. 
     
     
         8 . An electrode as in  claim 1 , wherein the release layer is water soluble. 
     
     
         9 . An electrode as in  claim 1 , wherein the release layer comprises a surfactant. 
     
     
         10 . An electrode as in  claim 1 , wherein at least 80 wt % of the release layer is a non-UV curable material. 
     
     
         11 . An electrode as in  claim 1 , wherein the current collector has a thickness of about 12 microns or less. 
     
     
         12 . An electrode as in  claim 1 , wherein the current collector is a metal layer. 
     
     
         13 . An electrode as in  claim 1 , wherein the current collector is electrochemically inactive. 
     
     
         14 . An electrode as in  claim 1 , wherein the current collector comprises an electrochemically active material. 
     
     
         15 . An electrode as in  claim 1 , wherein the electroactive material layer comprises lithium. 
     
     
         16 . An electrode as in  claim 1 , wherein the electroactive material layer comprises lithium metal. 
     
     
         17 . An electrode as in  claim 1 , wherein the electroactive material layer comprises sulfur. 
     
     
         18 . An electrode as in  claim 1 , wherein the electroactive material layer has a thickness of greater than about 15 microns. 
     
     
         19 . An electrode as in  claim 1 , further comprising one or more anode protective layers adjacent the electroactive material layer. 
     
     
         20 . An electrode, comprising:
 a first electroactive material layer;   a first current collector adjacent the first electroactive layer;   a first release layer adjacent the first current collector;   a second current collector adjacent the first release layer; and   a second electroactive material layer adjacent the second current collector.   
     
     
         21 . An electrode as in  claim 20 , further comprising a second release layer positioned between the first release layer and the second current collector. 
     
     
         22 . An electrode as in  claim 21 , further comprising an adhesion promoter positioned between the first and second current collectors. 
     
     
         23 . An electrode as in  claim 21 , further comprising an adhesion promoter positioned between the first and second release layers. 
     
     
         24 . An electrode as in  claim 21 , further comprising an adhesion promoter interspersed in the first and/or second release layers. 
     
     
         25 . An electrode as in  claim 20 , wherein the electroactive material layer comprises lithium metal. 
     
     
         26 . An electrochemical cell comprising the electrode of  claim 20  as an anode, further comprising a cathode comprising sulfur as an active cathode material. 
     
     
         27 . An electrode as in  claim 20 , wherein the first release layer has a thickness of about 10 microns or less. 
     
     
         28 . An electrode as in  claim 20 , wherein the first release layer comprises a polymeric material. 
     
     
         29 . An electrode as in  claim 20 , wherein the first release layer comprises poly(vinyl alcohol). 
     
     
         30 . A method of fabricating an electrode comprising at least a current collector and an electroactive material, comprising:
 positioning a release layer on a surface of a carrier substrate;   positioning a current collector on a surface of the release layer;   positioning an electroactive material layer adjacent the current collector layer; and   releasing the electrode from the carrier substrate.   
     
     
         31 . A method as in  claim 30 , wherein the carrier substrate comprises polyethylene terephthalate. 
     
     
         32 . A method as in  claim 30 , wherein the carrier substrate has a thickness of about 50 microns or greater. 
     
     
         33 . A method as in  claim 30 , wherein the carrier substrate has a thickness of about 20 microns or greater. 
     
     
         34 . A method as in  claim 30 , wherein the release layer has a higher adhesive affinity to the carrier substrate than to the current collector, such that the release layer adheres to the carrier substrate upon release of the electrode from the carrier substrate. 
     
     
         35 . A method as in  claim 30 , wherein the release layer has a higher adhesive affinity to the current collector than to the carrier substrate, such that the release layer adheres to the current collector upon release of the electrode from the carrier substrate. 
     
     
         36 . A method as in  claim 30 , wherein the release layer has a thickness of about 10 microns or less. 
     
     
         37 . A method as in  claim 30 , wherein the first release layer comprises a polymeric material. 
     
     
         38 . A method as in  claim 30 , wherein the first release layer comprises poly(vinyl alcohol). 
     
     
         39 . A method as in  claim 30 , further comprising applying an adhesion promoter adjacent the release layer after the releasing step. 
     
     
         40 . An article, comprising:
 an electroactive material layer;   a current collector adjacent the electroactive layer;   a release layer in contact with the current collector; and   a carrier substrate having a thickness greater than or equal to the thickness of the release layer in contact with the release layer, wherein the carrier substrate is releasable from the current collector by the release layer.   
     
     
         41 . An article as in  claim 40 , wherein the release layer has a higher adhesive affinity to the current collector than to the carrier substrate. 
     
     
         42 . An article as in  claim 40 , wherein the release layer has a higher adhesive affinity to the carrier substrate than to the current collector. 
     
     
         43 . An article as in  claim 40 , wherein the release layer has a thickness of about 10 microns or less. 
     
     
         44 . An article as in  claim 40 , wherein the first release layer comprises a polymeric material. 
     
     
         45 . An article as in  claim 40 , wherein the first release layer comprises poly(vinyl alcohol). 
     
     
         46 . An air- and moisture-tight package containing the article of  claim 40 . 
     
     
         47 . A method, comprising:
 providing a first electrode portion comprising a first electroactive material layer, a first current collector, and a first release layer;   providing a second electrode portion comprising a second electroactive material layer, a second current collector, and a second release layer; and   laminating the first and second electrode portions to form an assembly wherein the first and second release layers are facing one another.   
     
     
         48 . A method as in  claim 47 , further comprising positioning an adhesion promoter adjacent at least one of the first and second release layers prior to the lamination step. 
     
     
         49 . A method as in  claim 48 , wherein the adhesion promoter is in the form of a layer having a thickness between 0.01 and 3 microns. 
     
     
         50 . A method as in  claim 48 , comprising interspersing at least a portion of the adhesion promoter into at least one of the first and second release layers. 
     
     
         51 . A method as in  claim 48 , comprising interspersing a substantial portion of the adhesion promoter into at least one of the first and second release layers such that the adhesion promoter does not form a discrete layer between the first and second release layers. 
     
     
         52 . A method as in  claim 48 , wherein the adhesion promoter comprises a solvent and a polymer. 
     
     
         53 . A method as in  claim 48 , wherein the first and second release layers comprises a polymer having pendant hydroxide groups, and the adhesion promoter comprises a solvent comprising a sulfoxide. 
     
     
         54 . A method as in  claim 48 , wherein the first and second release layers comprises a polymer having pendant hydroxide groups, and the adhesion promoter comprises a solvent comprising a sulfoxide and a polymer having pendant hydroxide groups. 
     
     
         55 . A method as in  claim 48 , wherein the adhesion promoter comprises a solvent but does not include a polymer. 
     
     
         56 . A method as in  claim 47 , wherein the first current collector is positioned between the first electroactive layer and the first release layer. 
     
     
         57 . A method as in  claim 47 , wherein the second current collector is positioned between the second electroactive layer and the second release layer. 
     
     
         58 . A method as in  claim 47 , wherein at least one of the first and second release layers comprises a polymer. 
     
     
         59 . A method as in  claim 47 , wherein the lamination step comprises applying a solvent to a surface of the first release layer and solvating at least a portion of the first release layer, and then bringing the first and second release layers together. 
     
     
         60 . A method as in  claim 47 , wherein the lamination step comprises applying a solvent to a surface of the first release layer, and then bringing the first and second release layers together. 
     
     
         61 . A method as in  claim 47 , wherein the lamination step comprises activating the surface of the first and/or second release layers to promote adhesion to one another. 
     
     
         62 . A method as in  claim 47 , wherein positioning the release layer on the surface of the carrier substrate comprises the steps of:
 heating a mixture of a polymeric material and a solvent comprising an alcohol to a temperature of less than about 90° C.;   coating the surface of the carrier substrate with the mixture; and   removing at least a portion of the solvent from the mixture.   
     
     
         63 . An electrochemical cell comprising:
 an anode;   an electrolyte;   a cathode; and   a release layer having an adhesive affinity to at least one component of the electrochemical cell greater than its adhesive affinity to a substrate on which at least a portion of the electrochemical cell was fabricated, and providing essentially no electrochemical, structural, or activational feature to the electrochemical cell.