Gelated ionic liquid film-coated surfaces and uses thereof

Abstract

The invention relates to an assembly comprising a first gelated ionic liquid film in contact with a first electrically conductive surface, wherein the first gelated ionic liquid film comprises a first ionic liquid encapsulated within a gel matrix; and a second gelated ionic liquid film in contact with a second electrically conductive surface, wherein the second gelated ionic liquid film comprises a second ionic liquid encapsulated within a gel matrix; wherein the first and second gelated ionic liquid films are in contact with each other. There is also described an electrochemical cell comprising an assembly according to the invention, and methods for producing same.

1 . An electrochemical cell comprising:
 a first gelated ionic liquid film in contact with a first electrically conductive surface, wherein the first gelated ionic liquid film comprises a first ionic liquid encapsulated within a first gel matrix; and   a second gelated ionic liquid film in contact with a second electrically conductive surface, wherein the second gelated ionic liquid film comprises a second ionic liquid encapsulated within a second gel matrix;   wherein the first and second gelated ionic liquid films are in contact with each other, and   wherein the first gelated ionic liquid film further comprises a dissolved redox species.   
     
     
         2 . The electrochemical cell of  claim 1 , wherein either or both of:
 (i) one or both of the first and second ionic liquid comprises one or more anions selected from the group consisting of a halogen, a sulfonylimide, a carboxylate, and a fluorinated phosphate anion; and   (ii) one or both of the first and second ionic liquid comprises one or more cations selected from the group consisting of an alkylpyridinium, a dialkylimidazolium, a dialkylpyrrolidinium, a tetraalkylphosphonium, and a tetraalkylammonium cation.   
     
     
         3 . The electrochemical cell of  claim 2 , wherein the first and second electrically conductive surfaces are electrodes. 
     
     
         4 . The electrochemical cell of  claim 3 , wherein each electrode independently comprises one or more of graphite, doped carbon nanotubes, non-doped carbon nanotubes, doped graphene, non-doped graphene, a graphene composite, carbon paper, platinum, gold, or titanium. 
     
     
         5 . The electrochemical cell of  claim 3 , wherein the first electrically conductive surface is an anode, and the second electrically conductive surface is a cathode. 
     
     
         6 . The electrochemical cell of  claim 1 , wherein the first and second gelated ionic liquid films are immiscible when in contact with each other. 
     
     
         7 . The electrochemical cell of  claim 1 , wherein the first and/or second gelated ionic liquid film has a thickness of between about 50 μm and about 10 mm. 
     
     
         8 . The electrochemical cell of  claim 1 , wherein the first and/or second encapsulated ionic liquid comprises at least one of:
 (i) one or more anions selected from the group consisting of bromide, chloride, iodide, bis(trifluoromethyl-sulfonyl)imide, bis(fluorosulfonyl)imide, acetate, propionate, pentanoate, hexanoate, hexafluorophosphate, and tris(pentafluoro)trifluorophosphate; and   (ii) one or more cations selected from the group consisting of 1-butylpyridinium, 1-octylpyridinium, 1-(2-hydroxyethyl)pyridinium, 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-(2-methoxyethyl)-3-methylimidazolium, 1-(1-methoxymethyl)-3-methylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-1-ethylpyrolidinium, 1-methyl-1-butylpyrrolidinium, 1-methyl-1-hexylpyrolidinium, 1-(2-methoxyethyl)-1-methylpyrrolidinium, 1-(1-methoxymethyl)-1-methylpyrrolidinium, tetrabutylphosphonium, tributyloctylphosphonium, tributyl(2-methoxyethyl)phosphonium, tributyl-tert-butylphosphonium, tributyl(1-methoxymethyl)phosphonium, tetraethylammonium, tetrabutylammonium, tributyloctylammonium, tributyl(2-methoxyethyl)ammonium, tributyl(1-methoxymethyl)ammonium, and tributyl-tert-butylammonium.   
     
     
         9 . The electrochemical cell of  claim 1 , wherein said first and second gel matrices are formed from a gelating agent selected from one or more of a hydroxy-substituted organic compound, a polysaccharide, a dipeptide, a protein, a polymer, a poly(vinylidene fluoride-co-hexafluoropropylene) polymer, carbon nanotubes, non-doped or doped graphene, functionalised silica nanospheres, and a silica sol-gel. 
     
     
         10 . The electrochemical cell of  claim 1 , wherein the dissolved redox species is selected from the group consisting of:
 (a) an acetate, nitrate, sulfate, or triflate salt of Li + , Mg 2+ , Zn 2+ , Cu +/2+ , Fe 2+/3+ , Co 2+/3+ , Mn 2+ , or Cr 3+ ;   (b) a halogen;   (c) an oxygen, permanganate, dichromate, perchlorate, or halide salt of Li + , K + , Ca 2+ , Na + , or Mg 2+ ; and   (d) a mixture of any two or more of (a)-(c).   
     
     
         11 . The electrochemical cell of  claim 1 , wherein the second gelated ionic liquid film further comprises a second dissolved redox species selected from the group consisting of:
 (a) an acetate, nitrate, sulfate, or triflate salt of Li + , Mg 2+ , Zn 2+ , Cu +/2+ , Fe 2+/3+ , Co 2+/3+ , Mn 2+ , or Cr 3+ ;   (b) a halogen;   (c) an oxygen, permanganate, dichromate, perchlorate, or halide salt of Li + , K + , Ca 2+ , Na + , or Mg 2+ ; and   (d) a mixture of any two or more of (a)-(c).   
     
     
         12 . The electrochemical cell of  claim 1 , wherein one or more of:
 (i) either or both of the first and second gelated ionic liquid film comprises two or more different ionic liquids;   (ii) either or both of the first and second gelated ionic liquid film comprises two or more cations and two or more anions that together form a eutectic mixture; and   (iii) either or both of the first and second gelated ionic liquid film further comprises an electrolyte salt.   
     
     
         13 . The electrochemical cell of  claim 1 , wherein either or both of the first and second gelated ionic liquid film further comprises an electrolyte salt. 
     
     
         14 . The electrochemical cell of  claim 13 , wherein the electrolyte salt is soluble in at least one of the first ionic liquid and the second ionic liquid. 
     
     
         15 . The electrochemical cell of  claim 1 , which further comprises:
 a third gelated ionic liquid film in contact with a third electrically conductive surface, wherein the third gelated ionic liquid film comprises a third ionic liquid encapsulated within a third gel matrix; and   wherein the second and third gelated ionic liquid films are at least partially in contact with each other.   
     
     
         16 . The electrochemical cell of  claim 15 , wherein at least one of:
 the second and third gelated ionic liquid films are immiscible with each other; and   the first and third electrically conductive surfaces are anodes and the second electrically conductive surface is a cathode.   
     
     
         17 . A method of producing the electrochemical cell of  claim 1 , comprising:
 providing a first gelated ionic liquid film comprising a first encapsulated ionic liquid in contact with a first electrically conductive surface;   providing a second gelated ionic liquid film comprising a second encapsulated ionic liquid in contact with a second electrically conductive surface; and   contacting the first and second gelated ionic liquid films with each other.   
     
     
         18 . The method of  claim 17 , wherein at least one of said steps of providing comprises:
 combining a gelating agent with an ionic liquid at a suitable temperature to produce a mixture, and allowing the gelating agent to set and thereby form a gelated ionic liquid film in which the ionic liquid is encapsulated; and   contacting the mixture or the gelated ionic liquid film with an electrically conductive surface.   
     
     
         19 . The method of  claim 18 , wherein
 the mixture is contacted with the electrically conductive surface prior to allowing the gelating agent to set.   
     
     
         20 . The method of  claim 17  further comprising:
 providing a third gelated ionic liquid film comprising a third encapsulated ionic liquid in contact with a third electrically conductive surface; and 
 contacting the second and third gelated ionic liquid films.