Cathode material for polymer batteries and method of preparing same

Abstract

The invention provides a pre-mix of positive electrode material in transportable solid form comprising polymer and solid particles of electrochemically active material and/or electronically conductive additives and a process for preparing a pre-mix positive electrode in transportable solid form. The pre-mix positive electrode material may also comprise an alkali metal salt either dissolved or dispersed in the mixture. The invention also provides making a cathode film from the transportable solid pre-mix of positive electrode material.

1 . A pre-mix positive electrode material comprising a polymer and solid particles of electrochemically active material and electronically conductive additives, wherein the pre-mix positive electrode material is a transportable solid.  
     
     
         2 . A pre-mix of positive electrode material as defined in  claim 1  wherein the pre-mix of positive electrode material further comprises an alkali metal salt or alkali metal salt mix.  
     
     
         3 . A pre-mix of positive electrode material as defined in  claim 2  wherein the alkali metal salt is dispersed in the pre-mix of positive electrode material.  
     
     
         4 . A pre-mix of positive electrode material as defined in  claim 2  wherein the alkali metal salt is dissolved in the polymer of the pre-mix of positive electrode material.  
     
     
         5 . A pre-mix of positive electrode material as defined in  claim 1  further comprising an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         6 . A pre-mix of positive electrode material as defined in  claim 1  wherein the transportable solid is in a form selected from the group consisting of chunks, pucks, carrots, stripes, pellets, granules, powder, flakes and combinations thereof.  
     
     
         7 . A pre-mix of positive electrode material as defined in  claim 1  wherein the pre-mix of positive electrode material further comprises a small amount of water in the range of 1000 ppm to 10,000 ppm  
     
     
         8 . A pre-mix of positive electrode material as defined in  claim 2  further comprising fumed silica to inhibit adhesion of the transportable solids during transport or storage.  
     
     
         9 . A process for preparing a pre-mix positive electrode in transportable solid form comprising the steps of: 
 (a) In a mixing device, mixing together a polymer, at least one solvent and solid particles of electrochemically active material to form an mixture of polymer-solid particles;    (b) evaporating the at least one solvent present in the mixture of polymer-solid particles; and    (c) transforming the polymer-solid particles mixture into a transportable solid selected from the group consisting of chunks, pucks, carrots, stripes pellets, granules, powder, flakes and combinations thereof.    
     
     
         10 . A process as defined in  claim 9  wherein the dried polymer-solid particles mixture resulting from step (b) is transformed into a transportable solid by melting it through a melting and pumping device, thereafter cooling and hardening the melted polymer-solid particles mixture and thereafter breaking down the hardened polymer-solid particles mixture into a transportable solid shape through a mechanical cutting device.  
     
     
         11 . A process as defined in  claim 9  wherein the at least one solvent is evaporated and the polymer-solid particles mixture is transformed into a transportable solid by spray drying the polymer-solid particles mixture still in solution in the solvent through a nozzle thereby yielding a pre-mix positive electrode in transportable solid form selected from the group consisting of granules, powder and flakes.  
     
     
         12 . A process as defined in  claim 9  wherein the solid particles further comprise an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         13 . A process for preparing a pre-mix positive electrode in transportable solid form comprising the steps of: 
 (a) In a mixing device, mixing together a polymer, at least one solvent, an alkali metal salt and solid particles of electrochemically active material to form an mixture of polymer-salt-solid particles;    (b) evaporating the at least one solvent present in the mixture of polymer-salt-solid particles; and    (c) transforming the polymer-salt-solid particles mixture into a transportable solid selected from the group consisting of chunks, pucks, carrots, stripes, pellets, granules, powder, flakes and combinations thereof.    
     
     
         14 . A process as defined in  claim 13  wherein the dried polymer-salt-solid particles mixture resulting from step (b) is transformed into a transportable solid by melting it through a melting and pumping device, thereafter cooling and hardening the melted polymer-salt-solid particles mixture and thereafter breaking down the hardened polymer-salt-solid particles mixture into a transportable solid shape through a mechanical cutting device  
     
     
         15 . A process as defined in  claim 13  wherein the at least one solvent is a polar solvent.  
     
     
         16 . A process as defined in  claim 13  wherein the at least one solvent is a non-polar solvent.  
     
     
         17 . A process as defined in  claim 16  wherein the polymer, the non-polar solvent, the alkali metal salt and the solid particles are heated to a temperature of 40° C. or more while being mixed together in step (a).  
     
     
         18 . A process as defined in  claim 13  wherein the dried polymer-salt-solid particles mixture resulting from step (b) is transformed into a transportable solid by melting it through a melting and pumping device, thereafter cooling and hardening the melted polymer-salt-solid particles mixture and thereafter breaking down the hardened polymer-salt-solid particles mixture into a transportable solid shape through a mechanical cutting device.  
     
     
         19 . A process as defined in  claim 13  wherein the at least one solvent is evaporated and the polymer-salt-solid particles mixture is transformed into a transportable solid by spray drying the polymer-salt-solid particles mixture still in solution in the solvent through a nozzle thereby yielding a pre-mix positive electrode in transportable solid form selected from the group consisting of granules, powder and flakes.  
     
     
         20 . A process as defined in  claim 13  wherein the pre-mix positive electrode in transportable solid form is mixed with fumed silica to inhibit adhesion of the transportable solids during transport or storage  
     
     
         21 . A process as defined in  claim 13  wherein the solid particles further comprise an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         22 . A process for extruding a thin positive electrode sheet having at least 40%/wt solid content for a lithium polymer battery through a single or twin screw extruder, said process comprises the steps of: 
 (a) introducing a pre-mix of positive electrode material in solid form comprising a polymer and solid particles of electrochemically active cathode material, into a first feed throat of the extruder;    (b) melting the polymer and mixing said pre-mix of positive electrode material in the extruder;    (c) introducing in a second feed throat of the extruder an alkali metal salt which is dissolved in the polymer of the pre-mix of positive electrode material;    (d) extruding the positive electrode material through a die in the form of a thin sheet.    
     
     
         23 . A process for extruding d thin positive electrode sheet as defined in  claim 22  wherein said pre-mix of positive electrode material in solid form further comprises an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         24 . A process for extruding a thin positive electrode sheet as defined in  claim 23  wherein an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof is introduced into the extruder downstream from the pre-mix of positive electrode material in solid form.  
     
     
         25 . A process for extruding a thin positive electrode sheet as defined in  claim 22  wherein said thin sheet is from 5 to 200 μm thick.  
     
     
         26 . A process for extruding a thin positive electrode sheet having at least 40%/wt of solid content for a lithium polymer battery through a single or twin screw extruder, the process comprises the steps of: 
 (a) introducing into a first feed throat of the extruder an alkali metal salt; (b) introducing into a second feed throat of the extruder a pre-mix of positive electrode material in solid form comprising a polymer and solid particles of electrochemically active cathode material;    (b) melting and mixing said pre-mix of positive electrode material in the extruder and dissolving said alkali metal salt in the melted polymer; and    (c) extruding the positive electrode material through a die in the form of a thin sheet.    
     
     
         27 . A process for extruding a thin positive electrode sheet as defined in  claim 26  wherein said pre-mix of positive electrode material in solid form further comprises an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         28 . A process for extruding a thin positive electrode sheet as defined in  claim 26  wherein an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof is introduced into the extruder separate from the pre-mix of positive electrode material in solid form.  
     
     
         29 . A process for extruding a thin positive electrode sheet as defined in  claim 28  wherein said thin sheet is from 5 to 200 μm thick.  
     
     
         30 . A process for extruding a thin positive electrode sheet having at least 40%/wt of solid content for a lithium polymer battery through a single or twin screw extruder, the process comprises the steps of: 
 (a) introducing a pre-mix of positive electrode material in solid form comprising a polymer, an alkali metal salt and solid particles of electrochemically active cathode material and electronically conductive additives, into a first feed throat of the extruder;    (b) melting the polymer and mixing said pre-mix of positive electrode material in the extruder; and    (c) extruding the positive electrode material through a die in the form of a thin sheet.    
     
     
         31 . A process for extruding a thin positive electrode sheet as defined in  claim 30  wherein said thin sheet is from 5 to 200 μm thick.  
     
     
         32 . A process for making a positive electrode having at least 40%/wt of solid content for a lithium polymer battery, the process comprising the steps of: 
 (a) In a mixing device, mixing together a polymer, a solvent, and solid particles of electrochemically active material to form an mixture of polymer-solid particles;    (b) evaporating the solvent present in the mixture of polymer-solid particles;    (c) introducing the mixture of polymer-solid particles into a first feed throat of the extruder;    (b) melting the polymer and blending said mixture of polymer-solid particles in the extruder to form a positive electrode material; and    (c) extruding the positive electrode material through a die in the form of a thin sheet.    
     
     
         33 . A process for making a positive electrode as defined in  claim 32 , wherein said solid particles further comprise an electronic conductive additive selected from the group consisting of carbon, graphite and combinations thereof.  
     
     
         34 . A process for making a positive electrode as defined in  claim 32 , wherein said solid particles further comprise an alkali metal salt.  
     
     
         35 . A process for making a positive electrode as defined in  claim 32 , further comprising the step of introducing an alkali metal salt into a second feed throat of the extruder.  
     
     
         36 . A process for making a positive electrode as defined in  claim 32 , further comprising the step of introducing an electronic conductive additive into a second feed throat of the extruder.