Extruded battery components and manufacturing process

Abstract

The invention provides an apparatus and method for producing multilayer laminates of polymeric electrolyte material incorporating one of more electrode layers. The apparatus ( 40 ) comprises an extrusion apparatus ( 42 ) for extruding a polymeric material ( 76 ) and a pair of heated rollers ( 46, 48 ) between which the material ( 76 ) and electrodes ( 60, 68, 72 ) are pressed in order to produce a continuous extrudate ( 80 ). The method may also include producing a gellable mixture comprising a crystallisable polymer and an aprotic organic liquid, forming the mixture as an elongate tape and contacting the tape with an electrode material. A compression and heating step may be present.

1 . A method of producing a laminated electrical component incorporating a polymeric electrolyte layer and an electrode material layer characterised in that it comprises steps of:
 (i) producing a gellable mixture comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature, the ratio of the mass of the polymer to the mass of the liquid being from 1:4 to 2:3 and the mixture having a bulk ionic conductivity at said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at said first temperature and 10 Hz greater than 10 4  Pa;   (ii) forming the mixture as an elongate tape of desired width and depth;   (iii) contacting the tape from step (ii) with an electrode material at a temperature at which the tape, at least at the contact surface, is in the liquid phase; and   (iv) simultaneously or sequentially with step (iii) compressing the electrode material and mixture whereby an elongated laminated composite is formed.   
   
   
       2 . A method of producing a laminated electrical component incorporating a polymeric electrolyte layer and an electrode material layer characterised in that it comprises steps of:
 (i) producing a gellable mixture comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature, the ratio of the mass of the polymer to the mass of the liquid being from 1:4 to 2:3 and the mixture having a bulk ionic conductivity at said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at said first temperature and 10 Hz greater than 10 4  Pa;   (ii) extruding the mixture through an orifice of defined shape and dimension at a temperature at which it is in the form of a homogenous liquid phase;   (iii) contacting the extruded mixture in the liquid phase with an electrode material layer to produce a laminated composite comprising electrode and mixture layers;   (iv) compressing the laminated composite formed in (iii) while the mixture is still in the liquid phase whereby an elongate laminated composite of defined thickness is produced; and   (v) causing the laminate to cool such that the mixture is converted to a solid gel.   
   
   
       3 . A method of producing a laminated electrical component incorporating a polymeric electrolyte layer and an electrode material layer characterised in that it comprises steps of:
 (i) producing a polymeric electrolyte gel comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature, the ratio of the mass of the polymer to the mass of the liquid being from 1:4 to 2:3 and the mixture having a bulk ionic conductivity at said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at said first temperature and 10 Hz greater than 10 4  Pa;   (ii) forming the gel as an elongate tape of desired width and depth;   (iii) compressing the gel tape together with an electrode material while heating the tape, the tape and electrode material being contacted such that at least at the point of contact with the electrode material the tape is in the liquid phase whereby an elongate laminated composite is formed; and   (iv) causing the laminate so formed to cool such that the liquid phase is converted back into the gel phase.   
   
   
       4 . A method as claimed in  claim 1  in which the compression step comprises passing the electrode material and mixture through a nip formed between two or more rollers. 
   
   
       5 . A method as claimed in  claim 1 , and in which prior to contact of the mixture, whether in liquid or gel form, with the electrode material, an aprotic organic liquid is applied to one or more of the surfaces to be contacted. 
   
   
       6 . A method as claimed in  claim 4 , in which the aprotic organic liquid is applied to the mixture and/or the electrode surface just prior to the compressing step. 
   
   
       7 . A method as claimed in  claim 5 , in which the aprotic organic liquid is that which is used to make the mixture, or comprises any one of the component liquids used in that mixture. 
   
   
       8 . A method as claimed in  claim 5  in which the mixture comprises a further aprotic organic liquid which is too volatile for inclusion in the extrusion process due to the temperature at which the mixture is rendered liquid. 
   
   
       9 . A method as claimed in  claim 8 , in which the solvents are selected from a group comprising diethylcarbonate, 1,3-dioxolane, dimethylcarbonate, 1,2-dimethoxyetholane, dimethoxymethane, 1,3-dimethoxypropane, ethylmethyl carbonate, 1,2-diethoxyethane, dichloroethane. 
   
   
       10 . A method as claimed in  claim 9 , in which the liquids are added into the product at any stage after the step at which the electrolyte is initially extruded. 
   
   
       11 . A method as claimed in  claim 9 , and in which where any of the aforesaid liquids are added at the point of contact of the electrolyte and the electrode and they are supplied at a rate from 0.01 to 1 times that of the electrolyte on a weight per weight basis. 
   
   
       12 . A method as claimed in  claim 11 , in the liquids are added at 0.1 to 0.5 times weight by weight and still more preferably at from 0.2 to 0.3 times the weight. 
   
   
       13 . A method as claimed in  claim 11 , in which the rate of throughput of electrolyte component is at least 0.5 m/minute. 
   
   
       14 . A method as claimed in  claim 5 , and in which a high salt-solvent concentrate is added to provide the salting phase for the component. 
   
   
       15 . A method as claimed in  claim 4  and using a continuous extrusion process and in which the highly hygroscopic part of the process is conducted in the narrow space between extrudate and lamination between the rollers. 
   
   
       16 . A method as claimed in  claim 15  in which the salt is introduced into the polymer gel electrolyte via a concentrated solution of solvent and salt in the narrow space between extrudate and lamination between the rollers. 
   
   
       17 . A method as claimed in which the crystallisable polymer are selected from a group comprising a crystallisable polyhalo-olefin or copolymer thereof, more preferably being polyvinylidene fluoride (PVdF). 
   
   
       18 . A method as claimed in  claim 1  in which the aprotic liquid used to prepare the electrolyte mixture comprises one or more organic compounds selected from a group comprising or consisting one or more of monovalent type, such as —BF 4 , —PF 6 , —AsF 6 , —CF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , LiN(CF 3 CF 2 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , —CF 3 COO, SCN, —C10 4 , —Hgl 3 . 
   
   
       19 . A method as claimed in  claim 1  in which the mixture further includes one or more alkali or alkaline earth metal salts. 
   
   
       20 . A method as claimed in  claim 19  in which the alkali or alkaline earth metal salts are selected from a group consisting or comprising an alkali metal salt, a lithium salt. 
   
   
       21 . A method as claimed in  claim 1  in which salt is of any anion that is commonly used in polymeric electrolyte system cells. 
   
   
       22 . A method as claimed in  claim 21  in which the anion is monovalent. 
   
   
       23 . A method as claimed in  claim 18 , in which the metal salts are present at a concentration of 2% by mass or more based upon the weight of the organic aprotic liquid, more preferably at 4% by mass or more, preferably being up to its saturation concentration in any given mixture, but typically being up to 20% by mass, more typically up to 15% by mass. 
   
   
       24 . A method as claimed in  claim 1  in which the mixture is formed as a solid gel on cooling of the extruded material, that gel having a bulk ionic conductivity of greater than 10 −4  Siemens per centimetre and a dynamic modulus greater than 10 4  Pa at 20° C. 
   
   
       25 . A method as claimed in  claim 1  in which the mixture is degassed, more preferably as a gel, prior to contact with the electrode material. 
   
   
       26 . A method as claimed in  claim 1  in which the electrode incorporates a metal foil or open mesh gauze. 
   
   
       27 . A method as claimed in  claim 26  which the foil is loaded with active electrode material. 
   
   
       28 . A method as claimed in which the electrode is an anode comprising a copper foil loaded with a carbonatious material and/or the cathode is an aluminium foil loaded with a material selected from the group comprising: a lithiated manganese oxide material or a lithiated cobaltous oxide based material. 
   
   
       29 . A method as claimed wherein the component comprises both an anode and a cathode. 
   
   
       30 . A method as claimed in  claim 26  in which the foils are of less width than the polymeric electrolyte layer such as to ensure separation by the gel. 
   
   
       31 . A method as claimed in  claim 26  in which there is provided one foil of width smaller than the other to avoid contact in the final product. 
   
   
       32 . A method as claimed in  claim 1  and in which the salt is added to the resultant gel or gelling mixture after extrusion by a process which contacts the composite produced from step (iii) or (iv) with an aprotic solvent solution including the said salt or salts. 
   
   
       33 . A method as claimed in  claim 1 , and employing a process of solvent exchange whereby the extruded gel/electrode composite is contacted with a compatible solvent, which contains the salt which is desired to be added to the composite. 
   
   
       34 . A method as claimed in  claim 1  in which the polymeric electrolyte mixture is prepared prior to use and produced in particulate gelled form suitable for loading into an extrusion apparatus. 
   
   
       35 . A method as claimed in  claim 34  in which the gel is formed by premixing components in a dry environment, eg. dry box, heating this to form a homogeneous melt, cooling the melt to form a gel while degassing under reduced pressure, e.g. an appropriate degree of vacuum to remove gas in the appropriate time period, and then shaping the gel into pellets sized according to the size of the extrusion apparatus to be used such that ease of loading is ensured. 
   
   
       36 . A method as claimed in  claim 34  in which the preformed particulate or pelletted gel is loaded into the barrel of a ram extruder, the barrel heated to the melt temperature of the gel and the extrusion effected first, by advancing the extruder piston to void gases, then advancing it further at a desired controlled rate such that the gel extrudes, through the extruder die. 
   
   
       37 . A method as claimed in  claim 1  including the step of passing through a slot die, to produce a strip of electrolyte having a desired profile which, after compression, is of a desired component shape and dimension. 
   
   
       38 . A method as claimed in  claim 1  including the step of producing a continuous strip of set width and depth which can be rolled or otherwise sectioned. 
   
   
       39 . A method as claimed in  claim 38  in which the die slot is maintained at a temperature which is lower than that of the barrel. 
   
   
       40 . A method as claimed in  claim 1  in which heat is applied to heat the electrolyte mixture or gel to a temperature at which the dynamic modulus at 10 Hz is less than 10 5  Pa, more preferably less than 10 4  Pa and still more preferably 1×10 3  Pa or less, compresses it together with the electrode material such that the two form a laminate, and then causes the gel to cool such that the modulus is raised to 10 4  Pa or more, more preferably 10 5  Pa or more and still more preferably 10 6  Pa or more. 
   
   
       41 . A method as claimed in  claim 38  in which the extrudate exiting the die slot is layered onto an electrode which has been wetted with electrolyte solvent just prior to lamination. 
   
   
       42 . A method as claimed in  claim 41 , including the step of dripping the solvent onto the electrode at a rate matched to the rate of passage through a nip between heated rollers. 
   
   
       43 . A method as claimed in  claim 1  when applied to a lamination of electrolyte with one, two or more electrode layer and, optionally, with other layers, such as support layers. 
   
   
       44 . A method as claimed in  claim 43 , in which the support layers comprises Celgard®. 
   
   
       45 . A method as claimed in  claim 44 , in which the material is fed as a web between two extruded tapes of electrolyte which have been heated to the liquid or part liquid state, and then passing these together with one or more electrode layers simultaneously or sequentially through a desired nip or nips between two or more rollers. 
   
   
       46 . A method as claimed in  claim 1  when used to produce a component that has only one electrode layer, the further step of passing one such layer through a nip between rollers with the electrolyte. 
   
   
       47 . A method as claimed in  claim 1  when used to produce a component that has only one electrode layer the further step of passing said layer to be laminated through a nip between rollers with one or more backing strips, preferably wider than any of the layers to be laminated 
   
   
       48 . A method as claimed in  claim 1  including the step of accelerating the cooling in step by control of the temperature of a zone on which this occurs. 
   
   
       49 . An apparatus for producing a polymeric electrolyte component characterised by:
 (i) a source of tape of a gelled or gellable mixture comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature, the ratio of the mass of the polymer to the mass of the liquid being from 1:4 to 2:3 and the mixture having a having a bulk ionic conductivity at said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at said first temperature and 10 Hz greater than 10 4  Pa, the tape being of desired width and depth;   (ii) a source of electrode material in tape form oriented such as to receive the electrolyte tape on one of its surfaces;   (iii) a pair of rollers defining therebetween a nip and being located adjacent the point where the two tapes are contacted and which is capable of compressing these to produce an elongate laminated composite tape of defined thickness; and   (v) a cooling zone in which the extruded laminated is passively or actively cooled.   
   
   
       50 . An apparatus for producing a polymeric electrolyte component characterised by:
 (i) an extruder charged with a mixture of a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature, the ratio of the mass of the polymer to the mass of the liquid being from 1:4 to 2:3 and the solid electrolyte having a having a bulk ionic conductivity at said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at 10 Hz greater than 10 4  Pa, the extruder including a heater that maintains the mixture at a temperature at which it is in the liquid phase:   (ii) an extruder die having an orifice of defined shape and dimension which includes a heating apparatus set at a temperature at which the mixture remains in the liquid phase;   (iii) a supply of electrode material positioned below the orifice and oriented such as to receive extruded material from the orifice on at least one of its surfaces;   (iv) a pair of rollers defining therebetween a nip and being located adjacent the point where the extruded material and supply of electrode material are contacted which is capable of compressing these to produce an elongate composite of defined thickness; and   (v) a cooling zone in which the extruded laminated is passively or actively cooled such that the mixture becomes a solid phase gel.   
   
   
       51 . An apparatus as claimed in  claim 50  including a supply of aprotic organic liquid positioned such as be transferred to the surface of the electrolyte and/or electrode material prior to its contact with the electrolyte material. 
   
   
       52 . An apparatus as claimed in  claim 50  in which the material is supplied from one or more storage rolls which rotate to supply the nip rollers and in which the supply to the nip may be via one or more guide rollers and grip rollers. 
   
   
       53 . An apparatus as claimed in  claim 50  in which the rollers are heated to help in the forming of the composite laminate product. 
   
   
       54 . An apparatus as claimed in  claim 50  in which the extruder is a heated extruder with an associated mixing chamber capable of mixing the crystallisable polymer and the aprotic liquid. 
   
   
       55 . An apparatus as claimed in  claim 50  which the rollers are heated. 
   
   
       56 . An apparatus as claimed in  claim 50  and further including means for adding further electrodes prior to compressing. 
   
   
       57 . A multilayer composite material comprising a laminated structure including one or more electrode layers and a polymer electrolyte layer, characterised in that the electrolyte is a gel comprising a crystallised polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer a first temperature, but which is such a solvent at some higher temperature, the ratio of the mass of polymer to the mass of liquid being from 1:4 to 2:3 and the solid electrolyte having a having a bulk ionic conductivity at a said first temperature and 10 kHz greater than 10 −4  Siemens per centimetre and a dynamic modulus at 10 Hz greater than 10 −4  Pa at said first temperature. 
   
   
       58 . A material as claimed in  claim 57  in which the electrolyte has a dynamic modulus at 10 Hz greater than 10 5  Pa. 
   
   
       59 . A method as claimed in which said first temperature is 20° C. 
   
   
       60 . A method of producing a laminated electrical component incorporating a polymeric electrolyte layer and an electrode material layer characterised in that it comprises steps of:
 (i) producing a gellable mixture comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature but being a solvent for said polymer at some higher temperature;   (ii) forming the mixture as an elongate tape of desired width and depth;   (iii) contacting the tape from step (ii) with an electrode material at a temperature at which the tape, at least at the contact surface, is in the liquid phase; and   (iv) simultaneously or sequentially with step (iii) compressing the electrode material and mixture whereby an elongated laminated composite is formed.   
   
   
       61 . A multilayer battery comprising a laminated structure including one or more electrode layers and a polymer electrolyte layer, characterised in that the electrolyte is a gel comprising a crystallisable polymer and an aprotic organic liquid, the liquid not being a solvent for said polymer at a first temperature, but which is such a solvent at some higher temperature.