Protective coating for separators for electrochemical cells

Abstract

This invention pertains to separators for use in electrochemical cells which comprise at least one microporous pseudo-boehmite layer, which separator is in contact with at least one protective coating layer positioned on the anode-facing side of the separator opposite from the cathode active layer in the cell; electrolyte elements comprising such separators; electrical current producing cells comprising such separators; and methods of making such separators, electrolyte elements and cells.

1 . A separator for use in an electric current producing cell, wherein said cell comprises a cathode having a cathode active layer, an anode, and an electrolyte element interposed between said cathode and said anode, wherein said electrolyte element comprises said separator and an electrolyte; and said separator comprises at least one microporous pseudo-boehmite layer wherein said separator is in contact with at least one protective coating layer; and wherein at least one of said at least one protective coating layers is on the anode-facing side of said separator opposite from said cathode active layer of said cell.  
     
     
         2 . The separator of    claim 1   , wherein at least one of said protective coating layers on said anode-facing side comprises a polymer.  
     
     
         3 . The separator of    claim 2   , wherein said protective coating layer comprising a polymer is a single ion conducting layer.  
     
     
         4 . The separator of    claim 2   , wherein said protective coating layer comprising a polymer comprises a conductive polymer selected from the group consisting of poly(p-phenylene), polyacetylene, poly(phenylenevinylene), polyazulene, poly(perinaphthalene), polyacenes, and poly(naphthalene-2,6-diyl).  
     
     
         5 . The separator of    claim 1   , wherein at least one of said protective coating layers on said anode-facing side is a single ion conductive layer.  
     
     
         6 . The separator of    claim 1   , wherein at least one of said protective coating layers on said anode-facing side comprises a single ion conducting glass conductive to lithium ions.  
     
     
         7 . The separator of    claim 6   , wherein said single ion conducting glass is selected from the group consisting of lithium silicates, lithium borates, lithium aluminates, lithium phosphates, lithium phosphorus oxynitrides, lithium titanium oxides, lithium lanthanum oxides, lithium silicosulfides, lithium borosulfides, lithium aluminosulfides, lithium germanosulfides, and lithium phosphosulfides, and combinations thereof.  
     
     
         8 . The separator of    claim 1   , wherein at least one of said protective coating layers on said anode-facing side comprises a lithium phosphorus oxynitride.  
     
     
         9 . The separator of    claim 2   , wherein said protective coating layer has a thickness of from 0.2 to 20 microns.  
     
     
         10 . The separator of    claim 2   , wherein said protective coating layer has a thickness of from 0.5 to 5 microns.  
     
     
         11 . The separator of    claim 6   , wherein said protective coating layer has a thickness of from 5 n to 5 microns.  
     
     
         12 . The separator of    claim 1   , wherein said separator is in contact with a first and a second protective coating layer, wherein said first protective coating layer is in contact with said pseudo-boehmite layer on the side of said separator opposite from said cathode active layer, and said second protective coating layer is in contact with said first protective coating layer on the side opposite from said pseudo-boehmite layer.  
     
     
         13 . The separator of    claim 12   , wherein said second protective coating layer comprises a single ion conducting glass conductive to lithium ions.  
     
     
         14 . The separator of    claim 13   , wherein the combined thickness of said two protective coating layers is from 10 nm to 20 microns.  
     
     
         15 . The separator of    claim 2   , wherein said protective coating layer comprises one or more moieties formed by the polymerization of one or more monomers or macromonomers selected from the group consisting of monomers or macromonomers having the formula:  
       R 1 (R 2 O) n —R 3    
       wherein: 
 R 1  is the same or different at each occurrence and is selected from the group consisting of 
 CH 2 ═CH(C-O)—O—,  
 CH 2 ═C(CH 3 )(C═O)O—,  
 CH 2 ═CH—,  
                     
 CH 2 =CH—O—;  
 
 R 2  is the same or different at each occurrence and is selected from the group consisting of 
 —CH 2 —CH 2 —,  
 —CH(CH 3 )—CH 2 —,  
 —CH 2 —CH 2 —CH 2 —,  
 —CH(C 2 H 5 )—CH 2 —,  
 —CH 2 —CH 2 —CH 2 —CH 2 —;  
 
 R 3  is the same or different at each occurrence and is selected from the group consisting of cyano, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, 2-ethylhexyl, decyl, dodecyl, phenyl, butylphenyl, octylphenyl, nonylphenyl, R 1 , —X—(OR 2 ) m —R 1 , —Y[(OR 2 ) o —R 1 ] 2 , —Z[(OR 2 ) p —R 1 ] 3 ;  
 X is a divalent radical selected from the group consisting of  
                     
                     
 Y is a trivalent radical selected from the group consisting of  
                     
 Z is a tetravalent radical selected from the group consisting of  
                     
 m is an integer ranging from 0 to 100;  
 n is an integer ranging from 0 to 100;  
 o is an integer ranging from 0 to 100; and,  
 p is an integer ranging from 0 to 100.  
 
     
     
         16 . The separator of    claim 2   , wherein said protective coating layer comprises one or more moieties formed by polymerization of one or more acrylates selected from the group consisting of polyethylene glycol diacrylates, polypropylene glycol diacrylates, ethoxylated neopentyl glycol diacrylates, ethoxylated bisphenol A diacrylates, ethoxylated aliphatic urethane acrylates, ethoxylated alkylphenol acrylates, and alkyl acrylates.  
     
     
         17 . The separator of    claim 2   , wherein said protective coating layer comprises a polymer selected from the group consisting of polyacrylates, polymethacrylates, polyolefins, polyurethanes, polyvinyl ethers, polyvinyl pyrrolidones, acrylonitrile-butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene-styrene, sulfonated styrene/ethylene-butylene/styrene triblock polymers, and mixtures thereof.  
     
     
         18 . A method of making a separator for use in an electric current producing cell, wherein said cell comprises a cathode having a cathode active layer, an anode, and an electrolyte element interposed between said cathode and said anode, wherein said electrolyte element comprises said separator and an electrolyte; and said separator comprises at least one microporous pseudo-boehmite layer, wherein said separator is in contact with at least one protective coating layer; and wherein at least one of said protective coating layers is on the anode-facing side of said separator opposite from said cathode active layer of said cell;  
       wherein said method comprises the steps of: 
 (a) coating onto a substrate a first liquid mixture, A, comprising a boehmite sol, to form a first coating layer;  
 (b) drying the first coating layer formed in step (a) to form said separator comprising a microporous pseudo-boehmite layer;  
 (c) coating onto said separator layer formed in step (b) a mixture of a protective coating material to form a second coating layer;  
 (d) removing any volatile liquids of said second coating layer formed in step (c) to form a first protective coating layer on said anode-facing side of said separator.  
 
     
     
         19 . The method of    claim 18   , wherein said mixture of step (c) comprises one or more polymers, monomers, or macromonomers, and wherein step (d) comprises a step of drying the second coating layer formed in step (c) to form said first protective coating layer, wherein said first protective coating layer comprises a polymer.  
     
     
         20 . The method of    claim 18   , wherein said first protective coating layer is formed by a physical deposition process or a chemical vapor deposition process in steps (c) and (d).  
     
     
         21 . The method of    claim 20   , wherein said first protective coating layer comprises a single ion conducting glass conductive to lithium ions.  
     
     
         22 . The method of    claim 21   , wherein said single ion conducting glass is selected from the group consisting of lithium silicates, lithium borates, lithium aluminates, lithium phosphates, lithium phosphorus oxynitrides, lithium titanium oxides, lithium lanthanum oxides, lithium silicosulfides, lithium borosulfides, lithium aluminosulfides, lithium germanosulfides, and lithium phosphosulfides.  
     
     
         23 . The method of    claim 20   , wherein said first protective coating layer comprises a lithium phosphorus oxynitride.  
     
     
         24 . The method of    claim 20   , wherein said first protective coating layer comprises a conductive polymer selected from the group consisting of poly(p-phenylene), polyacetylene, poly(phenylenevinylene), polyazulene, poly(perinaphthalene), polyacenes, and poly(naphthalene-2,6-diyl).  
     
     
         25 . The method of    claim 19   , wherein said first protective coating layer has a thickness of from 0.2 to 20 microns.  
     
     
         26 . The method of    claim 19   , wherein said first protective coating layer has a thickness of from 0.5 to 5 microns.  
     
     
         27 . The method of    claim 20   , wherein said first protective coating layer has a thickness of from 5 nm to 5 microns.  
     
     
         28 . The method of    claim 18   , wherein after step (d) the method comprises a step (e) of coating onto the layer formed in step (d) a second protective coating layer.  
     
     
         29 . The method of    claim 28   , wherein step (e) comprises the steps of: 
 (i) coating onto said second coating layer formed in step (d) a mixture of a protective coating material to form a third coating layer;    (ii) removing any volatile liquids of said third coating layer formed in step (i) to form a second protective coating layer on said anode-facing side of said separator.    
     
     
         30 . The method of    claim 28   , wherein said second protective layer is formed in step (e) by a physical deposition process or a chemical vapor deposition process.  
     
     
         31 . The method of    claim 19   , wherein, subsequent to step (d), there is a step (e) of curing said protective coating layer to form a cured protective coating layer by use of an energy source.  
     
     
         32 . The method of    claim 31   , wherein said curing is performed using an energy source selected from the group consisting of heat, ultraviolet light, visible light, infrared radiation, and electron beam radiation.  
     
     
         33 . The method of    claim 19   , wherein at least one of said one or more polymers, monomers and macromonomers has a molecular weight which is too large for impregnation into the pores of said microporous pseudo-boehmite layer.  
     
     
         34 . The method of    claim 19   , wherein at least one of said one or more monomers and macromonomers for use in forming said protective coating layer is selected from the group consisting of monomers or macromonomers having the formula:  
       R 1 (R 2 O) n —R 3    
       wherein: 
 R 1  is the same or different at each occurrence and is selected from the group consisting of 
 CH 2 ═CH(C═O)—O—,  
 CH 2 ═C(CH 3 )(C═O)O—,  
 CH 2 ═CH—,  
                     
 CH 2 ═CH—O—;  
 
 R 2  is the same or different at each occurrence and is selected from the group consisting of 
 —CH 2 —CH 2 —,  
 —CH(CH 3 )—CH 2 —,  
 —CH 2 —CH 2 —CH 2 —,  
 —CH(C 2 H 5 )—CH 2 —,  
 —CH 2 —CH 2 —CH 2 —CH 2 —;  
 
 R 3  is the same or different at each occurrence and is selected from the group consisting of cyano, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, hexyl, 2-ethylhexyl, decyl, dodecyl, phenyl, butylphenyl, octylphenyl, nonylphenyl, R 1 , —X—(OR 2 ) m —R 1 , —Y[(OR 2 ) o —R 1 ] 2 , —Z[(OR 2 ) p —R 1 ] 3 ;  
 X is a divalent radical selected from the group consisting of  
                     
 Y is a trivalent radical selected from the group consisting of  
                     
 Z is a tetravalent radical selected from the group consisting of  
                     
 m is an integer ranging from 0 to 100;  
 n is an integer ranging from 0 to 100;  
 o is an integer ranging from 0 to 100; and,  
 p is an integer ranging from 0 to 100.  
 
     
     
         35 . The method of    claim 19   , wherein at least one of said one or more monomers or macromonomers is an acrylate selected from the group consisting of polyethylene glycol diacrylates, polypropylene glycol diacrylates, ethoxylated neopentyl glycol diacrylates, ethoxylated bisphenol A diacrylates, ethoxylated aliphatic urethane acrylates, ethoxylated alkylphenol acrylates, and alkyl acrylates.  
     
     
         36 . The method of    claim 19   , wherein said polymer of said first protective coating layer has a molecular weight greater than 10,000.  
     
     
         37 . The method of    claim 19   , wherein said polymer of said first protective coating layer has a molecular weight greater than 50,000.  
     
     
         38 . The method of    claim 19   , wherein said mixture of step (c) comprises a polymer.  
     
     
         39 . The method of    claim 38   , wherein said polymer is selected from the group consisting of polyacrylates, polymethacrylates, polyolefins, polyurethanes, polyvinyl ethers, polyvinyl pyrrolidones, acrylonitrile-butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene-styrene, sulfonated styrene/ethylene-butylene/styrene triblock polymers, and mixtures thereof.  
     
     
         40 . A method for making an electrolyte element for use in an electric current producing cell, wherein said electrolyte element comprises a separator comprising at least one microporous pseudo-boehmite layer, wherein said separator is in contact with at least one protective coating layer; and wherein at least one of said protective coating layers is on the anode-facing side of said separator opposite from a cathode active layer in said cell;  
       wherein said method comprises the steps of: 
 (a) coating onto a substrate a first liquid mixture, A, comprising a boehmite sol, to form a first coating layer;  
 (b) drying the first coating layer formed in step (a) to form said separator comprising a microporous pseudo-boehmite layer;  
 (c) coating onto said separator layer formed in step (b) a mixture of a protective coating material to form a second coating layer;  
 (d) removing any volatile liquids of said second coating layer formed in step (c) to form a first protective coating layer on said anode-facing side; and  
 (e) contacting a surface of the structure formed in step (d) with an electrolyte, thereby causing infusion of said electrolyte into the pores of said separator.  
 
     
     
         41 . The method of    claim 40   , wherein said mixture of step (c) comprises one or more polymers, monomers, or macromonomers, and wherein step (d) comprises a step of drying the second coating layer formed in step (c) to form said first protective coating layer, wherein said first protective coating layer comprises a polymer.  
     
     
         42 . The method of    claim 40   , wherein said first protective coating layer is formed by a physical deposition process or a chemical vapor deposition process in steps (c) and (d).  
     
     
         43 . The method of    claim 40   , wherein said method comprises, subsequent to step (d) and before step (e), a step of delaminating said separator layer from said substrate.  
     
     
         44 . The method of    claim 40   , wherein at least one outermost surface of said substrate comprises a cathode active layer and said first liquid mixture of step (a) is coated onto said cathode active layer.  
     
     
         45 . The method of    claim 40   , wherein said electrolyte comprises one or more materials selected from the group consisting of liquid electrolytes, gel polymer electrolytes, and solid polymer electrolytes.  
     
     
         46 . The method of    claim 40   , wherein said electrolyte is an organic electrolyte.  
     
     
         47 . The method of    claim 40   , wherein said electrolyte is an aqueous electrolyte.  
     
     
         48 . An electric current producing cell comprising a cathode, an anode, and an electrolyte element interposed between said cathode and said anode, wherein said electrolyte element comprises; 
 (a) a separator; and,    (b) an electrolyte;    wherein said separator comprises at least one microporous pseudo-boehmite layer, wherein said separator is in contact with at least one protective coating layer; and wherein at least one of said at least one protective coating layers is on the anode-facing side of said separator opposite from said cathode active layer of said cell, and said electrolyte is contained within the pores of said separator.    
     
     
         49 . The cell of    claim 48   , wherein said cell is a secondary electric current producing cell.  
     
     
         50 . The cell of    claim 48   , wherein said cell is a primary electric current producing cell.  
     
     
         51 . An electric current producing cell comprising a cathode, an anode, and an electrolyte element interposed between said cathode and said anode, wherein said electrolyte element comprises: 
 (a) a separator; and,    (b) an organic electrolyte;    wherein, said separator comprises:    (i) a microporous pseudo-boehmite layer, in contact with    (ii) a protective coating layer comprising a polymer; and,    wherein said organic electrolyte is contained within the pores of said separator.    
     
     
         52 . The cell of    claim 51   , wherein said protective coating layer is on the anode-facing side of said separator opposite from said cathode.  
     
     
         53 . A method of forming an electric current producing cell, said method comprising the steps of: 
 (a) providing an anode;    (b) providing a cathode; and,    (c) interposing an electrolyte element between said anode and said cathode, wherein said electrolyte element comprises (i) a separator according to    claim 1   ; and (ii) an electrolyte within the pores of said separator.    
     
     
         54 . The method of    claim 53   , wherein said electrolyte of said electrolyte element comprises one or more electrolytes selected from the group consisting of liquid electrolytes, gel polymer electrolytes, and solid polymer electrolytes.