Graphene has attracted much interest due to its unique electrical and mechanical properties, ultra-high surface area, and the fact that it is a pure carbon based material and as such is an environmentally friendly alternative to transition metal based battery materials. While some applications require high-quality single layer graphene, others such as energy storage require bulk materials. The properties of these graphene bulk materials strongly depend on the way how the individual graphene sheets are linked together. LLNL has developed a process to covalently link single or double layer graphene sheets together to form a macroscopic, monolithic material that has excellent mechanical and electrical properties. The material is ideal for electrical energy storage applications or to make a device that is best described as a macroscopic 3D field effect transistor/resistor. The performance of this material for both applications depends on the electronic structure of the material which, for example, can be modified by doping with nitrogen.
Covalent cross-linking of graphene sheets is achieved by using carbon nanoparticles as cross-linker for randomly oriented single layered graphene oxide nanoplatelets. The use of a covalently integrated carbon binder makes these graphene aerogel foams mechanically very robust, and allows one to achieve high bulk electrical conductivities even at low densities.
Our graphene based macro-assemblies have many promising applications, including, for example, as electrode material in supercapacitors, capacitive desalination, and as a bulk material with dynamically tunable conductivity. Our graphene based macro-assemblies are chemically inert and mechanically robust, they have one the highest gravimetric surface areas reported, and the ingredients are relatively inexpensive.
| Feature | Benefit |
|---|---|
| Our graphene based macro-assemblies are covalently cross-linked | The material is mechanically robust, and has high bulk electrical conductivity |
| The electronic structure can be engineered by incorporating nitrogen | Nitrogen incorporation increases the electrical energy storage capacity |
| Our graphene macro-assemblies have a very high surface area that is accessible via an open porosity | Bulk material with dynamically tunable electrical properties by electrochemical gating |
The technology is developed and good performance for the above mentioned applications has been demonstrated.
LLNL has filed for patent protection on this invention.