Bipolar structures for use with electrochemical devices, and associated systems and methods

Abstract

Disclosed herein are polymer conductive films for use with electrochemical devices. An exemplary electrochemical device can include an anode, a cathode, and a bipolar structure disposed between the anode and cathode. The bipolar structure includes a film having a plurality of conductive particles and a plurality of non-conductive polymers, wherein the polymers are integrated with the particles such that the film is non-porous and substantially compositionally homogeneous along a length and/or thickness of the film.

I/We claim: 
     
         1 . An electrochemical device, comprising:
 an anode;   a cathode; and   a bipolar structure disposed between the anode and cathode, the bipolar structure comprising-
 a first layer proximate the anode; 
 a second layer proximate the cathode; and 
 a film disposed between the first and second layers, the film comprising a plurality of conductive particles and a plurality of non-conductive polymers, the polymers being integrated with the conductive particles such that (i) the film forms an impermeable layer to fluid, and (ii) an outer surface of the film is compositionally homogenous. 
   
     
     
         2 . The device of  claim 1 , wherein the polymers comprise at least one of polyethylene, polyurethane, PTFE, or PVDF. 
     
     
         3 . The device of  claim 2 , wherein:
 the first and second layers each comprise graphite,   the film directly contacts each of the first layer and the second layer via opposing planar surfaces of the film, and   the first layer directly contacts the anode such that the graphite of the first layer compressively conforms to a surface of the anode.   
     
     
         4 . The device of  claim 2 , wherein the particles comprise at least one of graphite, carbon black, copper, iron, oxides, or tin oxide. 
     
     
         5 . The device of  claim 1 , wherein the film is anisotropic such that, in operation, a first conductive pathway through the film from one of the anode or cathode to the other of the anode of cathode has less resistance than a second conductive pathway along a surface of the film. 
     
     
         6 . The device of  claim 1 , wherein the polymers comprise between 20%-50% of the film by weight or volume. 
     
     
         7 . The device of  claim 6 , wherein the film consists of only the polymers and the conductive particles, and wherein the conductive particles comprise between 50-80% of the film by weight or volume such that the film has a net volume resistivity less than 1000 ohm-cm. 
     
     
         8 . The device of  claim 1 , wherein the film has a thickness between 0.1 millimeters (mm) and 0.3 mm. 
     
     
         9 . The device of  claim 1 , wherein:
 the outer surface is a first outer surface facing the anode, and   the electrical and/or chemical properties at the first outer surface of the film differ from the respective electrical and/or chemical properties at a second outer surface of the film facing the cathode.   
     
     
         10 . A battery, comprising:
 electrolyte fluid; and   an electrochemical device surrounded by the electrolyte fluid, the electrochemical device comprising-
 an anode; 
 a cathode; and 
 a bipolar structure disposed between the anode and cathode, the bipolar structure comprising-
 a first layer proximate the anode; 
 a second layer identical to the first layer and proximate the cathode; and 
 a film disposed between the first and second layers, the film comprising a plurality of non-conductive polymers that form an impermeable layer configured to prevent the electrolyte fluid from passing therethrough. 
 
   
     
     
         11 . The battery of  claim 10 , wherein the film further comprises a plurality of conductive particles integrated with the polymers such that an outer surface of the film is compositionally homogenous. 
     
     
         12 . The battery of  claim 10 , wherein the polymers comprise at least one of polyethylene, polyurethane, PTFE, or PVDF. 
     
     
         13 . The battery of  claim 12 , wherein the first and second layers each comprise a graphite sheet. 
     
     
         14 . The battery of  claim 13 , wherein:
 the film directly contacts each of the first layer and the second layer via opposing planar surfaces of the film,   the first layer directly contacts the anode such that the graphite of the first layer compressively conforms to a surface of the anode, and   the second layer directly contacts the cathode such that the graphite of the second layer compressively conforms to a surface of the cathode.   
     
     
         15 . The battery of  claim 10 , wherein the polymers comprises between 20%-50% of the film by weight or volume. 
     
     
         16 . The battery of  claim 15 , wherein the film consists of only the polymers and the conductive particles, and wherein the conductive particles comprise between 50-80% of the film by weight or volume such that the film has a net volume resistivity less than 1000 ohm-cm. 
     
     
         17 . A method of manufacturing an electrochemical device, the method comprising:
 combining a plurality of conductive particles and a plurality of non-conductive polymers to form a first structure that is substantially compositionally homogenous and impermeable to fluid;   rolling the first structure to form a second structure having a thickness of no more than 0.5 millimeters;   cutting the second structure to form a film having a predetermined length and width; and   disposing the film between a first layer and a second layer to form a bipolar structure, the first and second layers comprising graphite; and   operably coupling the bipolar structure to an anode and cathode such that the graphite of each of the first and second layers compressively conform to a respective surface of the anode and cathode.   
     
     
         18 . The method of  claim 17 , wherein the polymers comprise at least one of polyethylene, polyurethane, PTFE, or PVDF, and wherein the particles comprise at least one of graphite, carbon black, copper, iron, oxides, or tin oxide. 
     
     
         19 . The method of  claim 17 , wherein the polymers comprise between 20%-50% of the film by weight or volume. 
     
     
         20 . The method of  claim 19 , wherein the film consists of only the polymers and the conductive particles, and wherein the conductive particles comprise between 50-80% of the film by weight or volume such that the film has a net volume resistivity less than 1000 ohm-cm.