Safe battery solvents

Abstract

An ion transporting solvent maintains very low vapor pressure, contains flame retarding elements, and is nontoxic. The solvent in combination with common battery electrolyte salts can be used to replace the current carbonate electrolyte solution, creating a safer battery. It can also be used in combination with polymer gels or solid polymer electrolytes to produce polymer batteries with enhanced conductivity characteristics. The solvents may comprise a class of cyclic and acyclic low molecular weight phosphazenes compounds, comprising repeating phosphorus and nitrogen units forming a core backbone and ion-carrying pendent groups bound to the phosphorus. In preferred embodiments, the cyclic phosphazene comprises at least 3 phosphorus and nitrogen units, and the pendent groups are polyethers, polythioethers, polyether/polythioethers or any combination thereof, and/or other groups preferably comprising other atoms from Group 6B of the periodic table of elements.

1 . A battery, comprising: 
 an anode, a cathode, and an electrolyte solution comprising at least one phosphazene compound comprising: 
 at least two phosphorus-nitrogen units comprising two pendent groups bonded to each phosphorus atom of the at least two phosphorus-nitrogen units, wherein each of the two pendent groups comprises a polyether group, a polythioether group, or a polyether/polythioether group.  
   
   
   
       2 . The battery of  claim 1 , wherein the at least one phosphazene compound comprises from two phosphorus-nitrogen units to ten phosphorus-nitrogen units.  
   
   
       3 . The battery of  claim 1 , wherein at least one of the two pendent groups comprises a linear pendent group.  
   
   
       4 . The battery of  claim 1 , wherein at least one of the two pendent groups comprises a branched pendent group.  
   
   
       5 . The battery of  claim 1 , wherein the at least one phosphazene compound comprises at least one homotrimer.  
   
   
       6 . The battery of  claim 1 , wherein the at least one phosphazene compound comprises at least one heterotrimer.  
   
   
       7 . The battery of  claim 1 , wherein each of the two pendent groups is bonded to the phosphorus atom through an oxygen linkage, a sulfur linkage, a selenium linkage, a tellurium linkage, or a polonium linkage.  
   
   
       8 . The battery of  claim 1 , wherein each of the two pendent groups comprises a polyether group.  
   
   
       9 . The battery of  claim 1 , wherein each of the two pendent groups comprises a polythioether group.  
   
   
       10 . The battery of  claim 1 , wherein each of the two pendent groups comprises a polyether/polythioether group.  
   
   
       11 . The battery of  claim 1 , wherein one of the two pendent groups comprises a linear polyether/polythioether group and the other of the two pendent groups comprises a branched polyether/polythioether group.  
   
   
       12 . The battery of  claim 1 , wherein each of the two pendent groups is selected from the group consisting of a polyether group, a polythioether group, and a polyether/polythioether group.  
   
   
       13 . The battery of  claim 1 , wherein the two pendent groups do not comprise a halogen atom.  
   
   
       14 . The battery of  claim 1 , wherein the at least one phosphazene compound comprises at least one compound having the chemical formula of:  
     
       
         
         
             
             
         
       
       wherein each of X and Y is selected from the group consisting of oxygen, sulfur, selenium, tellurium, and polonium, n is from 1 to 10, and z is from 1 to 6.  
     
   
   
       15 . The battery of  claim 1 , wherein the electrolyte solution consists of the at least one phosphazene compound.  
   
   
       16 . The battery of  claim 1 , further comprising a porous separator.  
   
   
       17 . The battery of  claim 1 , further comprising at least one solvent.  
   
   
       18 . The battery of  claim 1 , wherein the at least one solvent comprises at least one organic carbonate solvent selected from the group consisting of ethylene carbonate, diethylene carbonate, and propylene carbonate.  
   
   
       19 . A battery comprising an anode, a cathode, and an electrolyte solution comprising at least one phosphazene compound having the chemical formula of:  
     
       
         
         
             
             
         
       
       wherein each of X and Y is selected from the group consisting of oxygen, sulfur, selenium, tellurium, and polonium, n is from 1 to 10, and z is from 1 to 6.  
     
   
   
       20 . The battery of  claim 19 , wherein the at least one phosphazene compound comprises a compound selected from the group consisting of:  
     
       
         
         
             
             
         
       
     
   
   
       21 . A battery, comprising: 
 an anode, a cathode, and an electrolyte solution comprising at least one phosphazene compound comprising: 
 at least two phosphorus-nitrogen units comprising at least two pendent groups bonded to each phosphorus atom of the at least two phosphorus-nitrogen units and a terminal group bonded to a terminal nitrogen atom of the at least two phosphorus-nitrogen units, wherein each of the at least two pendent groups comprises a polyether group, a polythioether group, or a polyether/polythioether group.  
   
   
   
       22 . The battery of  claim 21 , wherein the terminal group comprises hydrogen, an alkyl group, an alkene group, an alkoxide group, a polyether group, a polythioether group, a siloxane group or —X(CH 2 ) n Y(CH 2 ) n Y(CH 2 ) n  . . . Y(CH 2 ) n CH 3 , wherein each n is from 1 to 6 and each of X and Y is selected from the group consisting of oxygen, sulfur, selenium, tellurium, and polonium.  
   
   
       23 . The battery of  claim 21 , wherein the at least one phosphazene compound has the chemical formula of:  
     
       
         
         
             
             
         
       
       wherein m is from 2 to 6, each of R 1  and R 2  has the chemical formula of —X(CH 2 ) n Y(CH 2 ) n Y(CH 2 ). Y(CH 2 ) n CH 3 , each n is from 1 to 6, each of X and Y is selected from the group consisting of oxygen, sulfur, selenium, tellurium, and polonium, and each of R 3  and R 4  is selected from the group consisting of —X(CH 2 ) n Y(CH 2 ) n Y(CH 2 ) n  . . . Y(CH 2 ) n CH 3 , hydrogen, an alkyl group, an alkene group, an alkoxide group, a polyether group, a polythioether group, and a siloxane group.  
     
   
   
       24 . The battery of  claim 21 , wherein the at least one phosphazene compound is not poly(bis(methoxyethoxyethoxy))phosphazene.