Graphene-Clay Based Nanomaterials for Clean Energy Storage

Groundwork results showing the possibility of applying supported graphene materials prepared from natural resources in the use of clean energy are introduced here. These nanomaterials were generated in an eco-friendly approach from caramel adsorbed on the fibrous and porous clay mineral sepiolite, which was thermally treated at relatively moderate temperature in the absence of oxygen. The supported graphenes produced in this way exhibit good electrical conductivity and an elevated specific surface area, making them excellent candidates as electrodes for storage devices such as Li-ion batteries and supercapacitors. In this way, electrochemical cells involving supported graphenes as anode materials and lithium metal as cathode material were successfully tested in model Li-rechargeable batteries, which exhibited specific capacity values close to 400 mA h/g and enhanced cyclability behavior. In the same way, the use of clay-supported graphenes in supercapacitors was tested showing specific capacity values higher than 30 F/g. In addition, these carbon nanomaterials can act as adsorbents for hydrogen storage, achieving at 77 K and 40 MPa adsorption capacities above 0.6 wt.% of hydrogen related to the total mass of the system and a maximum value close to 1.7 wt.% of hydrogen specifically related to the carbon mass.