Thermal interface composite material and method

Abstract

A composite thermal interface material and methods are shown. Devices such as lithium ion batteries incorporating composite thermal interface materials show significant improvement in cooling performance. In one example, composite thermal interface materials shown provide cooling through both a phase change mechanism, and a heat conducting mechanism which directs heat away from the device to be cooled, such as electrochemical cells in a battery, to an external housing and/or a coupled heat exchange device such as radiating fins.

What is claimed is: 
     
         1 . A thermal interface composite, comprising:
 a hydrocarbon matrix material; and   a number of graphene particles dispersed within the hydrocarbon matrix material.   
     
     
         2 . The thermal interface composite of  claim 1 , wherein the hydrocarbon matrix material includes paraffin. 
     
     
         3 . The thermal interface composite of  claim 1 , wherein the number of graphene particles dispersed within the hydrocarbon matrix includes a loading percentage between approximately 1% and 20%. 
     
     
         4 . The thermal interface composite of  claim 1 , wherein a composite thermal conductivity of the thermal interface composite is between approximately 15 W/mK and 45 W/mK. 
     
     
         5 . The thermal interface composite of  claim 1 , wherein the number of graphene particles includes particles with a size distribution range between approximately 150 nanometers and 300 nanometers. 
     
     
         6 . The thermal interface composite of  claim 1 , wherein the hydrocarbon matrix material has a melting temperature of between approximately 60° C. and 80° C. 
     
     
         7 . A method of cooling a battery, comprising:
 absorbing an amount of heat generated by one or more electrochemical cells, using a solid to liquid phase change in at least one component of a thermal interface composite;   concurrently conducting heat away from the one or more electrochemical cells to an external battery housing through a heat conducting dispersed phase located within the thermal interface composite.   
     
     
         8 . The method of  claim 7 , wherein absorbing the amount of heat generated by one or more electrochemical cells includes absorbing an amount of heat generated by one or more lithium ion cells. 
     
     
         9 . The method of  claim 7 , wherein the solid to liquid phase change includes a solid to liquid phase change in a paraffin matrix material. 
     
     
         10 . The method of  claim 7 , wherein conducting heat away from the one or more electrochemical cells includes conducting heat through a number of dispersed graphene particles. 
     
     
         11 . A method of cooling a battery, comprising:
 absorbing an amount of heat generated by one or more electrochemical cells, using a solid to liquid phase change in at least one component of a thermal interface composite;   concurrently conducting heat away from the one or more electrochemical cells to an external battery housing through a uniformly distributed carbon particle dispersed phase located within the thermal interface composite.   
     
     
         12 . The method of  claim 11 , wherein conducting heat away from the one or more electrochemical cells includes conducting heat at least partially through a graphene particle dispersed phase located within the thermal interface composite. 
     
     
         13 . The method of  claim 12 , wherein conducting heat away from the one or more electrochemical cells includes conducting heat at least partially through graphene particles with a lateral size in a range of 150 and 3000 nm. 
     
     
         14 . The method of  claim 11 , wherein the solid to liquid phase change is a phase change in a paraffin matrix material. 
     
     
         15 . A method of cooling a battery, comprising:
 absorbing an amount of heat generated by a plurality of electrochemical cells housed in an external battery housing, using a solid to liquid phase change in at least one component of a thermal interface composite;   concurrently conducting heat away from the plurality of electrochemical cells to the external battery housing through a uniformly distributed graphene particle dispersed phase located within the thermal interface composite.   
     
     
         16 . The method of  claim 15 , wherein conducting heat away from the plurality of electrochemical cells to the external battery housing includes conducting heat to an aluminum battery housing. 
     
     
         17 . The method of  claim 15 , further including conducting heat through one or more cooling fins coupled to the external battery housing. 
     
     
         18 . The method of  claim 15 , wherein using a solid to liquid phase change includes changing from solid to liquid at a temperature between approximately 60° C. and 80° C. 
     
     
         19 . The method of  claim 15 , wherein conducting heat away from the plurality of electrochemical cells includes conducting heat at least partially through graphene particles with an average flake thickness of 8 nm. 
     
     
         20 . The method of  claim 15 , wherein conducting heat away from the plurality of electrochemical cells includes conducting heat at least partially through a uniformly distributed graphene particle dispersed phase having a loading percentage of approximately 20%. within the thermal interface composite. 
     
     
         21 . The method of  claim 20 , wherein conducting heat away from the plurality of electrochemical cells includes conducting heat at least partially through graphene particles with an average flake thickness of approximately 1 nm with an average lateral dimension of ˜10 μm.