The SOMABAT project targeted the following objectives:
- achieving a lithium battery in which at least 50% (in weight) of the battery would be recyclable,
- reducing the total manufacturing cost of the battery down to 150€/kg thanks to recyclability,
- obtaining a high energy density, i.e. higher than 220 Wh/kg, and
- improving the battery safety (e.g. issues related to leakages, short circuits, overcharge).
The challenge of developing such a low cost, environmental friendly and energy efficient designed battery was met by making use of low-cost synthesis and processing methods in which it was possible to tailor the different targeted features.
The SOMABAT project began in January 2011. It was co-financed by the FP 7 grant funding programme and gathered 13 partners from 9 European countries. It was coordinated by Instituto Tecnológico de la Energía (Spain) and lasted 36 months.
The core output of the project consisted in designing, modelling and integrating a set of innovative materials in a battery cell that would be easily incorporated in electric vehicles.
The anode was designed with novel carbon/carbon composite materials. These materials were synthetized with graphite materials and carbon porous xerogels or carbon material obtained from agricultural waste precursors (i.e. olive stones and orange skin). It was found that the carbon/carbon composite showed high reversible capacity as well as good cyclability.
The cathode was based on LiFePO4 and LiFeMnPO4. Materials with nano-sized particles were synthesized and assembled into larger micro-sized aggregates in order to provide an ideal microstructure for electrode purposes.
The electrolyte membrane was based on fluorinated matrices with nano-sized particles. It was synthetized with co-polyphosphoesters and commercial acrylates, containing lithiumfluoromethanesulfate by UV curing. The membrane obtained was characterized by FTIR spectroscopy and thermal analysis (TG/DSC).
Moreover, the development of this lithium polymer battery took into account the recyclability of the components.
Finally, a complete LCA was carried out, including the definition of the functional unit and the system boundaries. The functional unit of the battery has been defined as follows: it is the amount of energy (30 kW/h) accumulated by the battery and delivered to an electric vehicle capable of sustaining 4000 charge cycles at 80% discharge, thereby allowing a 210 000 km operation.
Why did it work?
The eco-design of the battery is a key point. The development considered in SOMABAT did not only cover the technical objective (i.e. high energy density) and the economical aspect (by targeting new low cost synthesis and processing methods) but also the environmental aspect through the recyclability and the sustainability assessment of the battery (i.e. complete LCA analysis).
Moreover, the project involved not only universities and technical centres and experts but also battery manufacturing companies to support them in building up their network.
As the different components of the battery have been assembled and tested, the technology readiness level is estimated to be 5 on the TRL scale.
The system would further be demonstrated in the field and incorporated in a commercial design.