Design of new metallic oxide-carbon hybrid composites for supercapacitors electrodes - MOC@SUPCAP

Project summary

The objective of the MOC@SUPCAP project is to develop a novel class of hybrid composite electrodes with high performance targeted for the next generation supercapacitors, namely asymmetric supercapacitors, based on cheap and reliable fabrication methods. Needs addressed: Supercapacitors (SC) are energy storage devices, essential to support the peak loads/consumption in renewables production and that can complement batteries due to their higher power density. SC exhibit unique features such as high power density, and fast charge/discharge rates, sustaining up to millions of cycles. However, they lack energy density when compared to batteries. This drawback can be mitigated by developing new electrode materials combining higher specific capacitance and therefore enhanced power and energy densities. The answer resides in developing new composite electrodes with highly porous hierarchical structures, combining enhanced double layer capacitance, typical of carbon-based materials with the pseudocapacitance behaviour of transition metal oxides. Composite electrodes composed of transition metals oxides (NiO2, Co3O4, MnO2 and V2O5) and carbon (like cloth/fibre and graphene) are a promising route when tailored as porous hierarchical two-dimensional (2D) or three-dimensional (3D) structures. The preparation of these structures should, however, be simple and flexible, allowing fine tuning of the surface properties in order to fulfil the requirements of electrodes for high performance SC. The innovative contribution lies in the design and fabrication of deposited tailor made transition metallic oxides on C based substrates to obtain high performance composite electrodes. The metallic oxides will be obtained by simple, flexible and low-cost routes (electrodeposition and wet chemical synthesis methods) which are easily scaled-up. For example, the production of structured oxides by pulsed cathodic electrodeposition is a novel approach to this process that is already widely used in the industry for the production of coatings. Results: A new class of hybrid composite electrodes based on assemblies of carbon materials (for enhanced double layer response) and porous transition metals oxides (for high faradaic contribution) will be developed. The combined advantages of carbon with those of transition metals oxides will enable more effective supercapacitors, able to work with environmentally friendly aqueous electrolytes. Furthermore they can be easily assembled in asymmetric devices, which combine a battery electrode with a supercapacitor electrode. A specific capacitance above 500 Fg-1, an operating voltage larger than 1.5 V and high cycling stability will be targeted as sought-after characteristics of the designed hybrid composite electrodes. The MOC@SUPCAP project outputs are: - more efficient composite supercapacitor electrodes consisting of carbon and transition metallic oxides, with additional ability to undergo various redox processes; - the implementation of cheaper fabrication processes capable of producing novel classes of nanostructured porous oxides/carbon composite materials; - to foster new Hi-Tech applications, combining the traditional electrodeposition or wet chemical methods of producing metallic oxides with new advanced materials such as graphene; - advanced physical, chemical and electrochemical characterisation and fundamental knowledge on electrochemical behaviour of such electrodes using transient mathematical models, predicting efficiency, performance and lifetime. The project addresses some of the most important concerns of current times: sustainable energy production and efficient energy storage for a cleaner environment while contributing to sustainable economic growth, boosting of new markets, creation of jobs and social well being. The proposal is thus, by no doubt, in the scope of the call topic "Materials for Energy Systems".