Electrode Materials and Electrolytes Development for Ageing Resistant Li-Ion High Energy Pouch Cells for the Electric Vehicle

In order to make the electric car appealing for the average consumer, it is mandatory to offer a vehicle capable of running for about 200 km with a single charge, to avoid long and unpopular recharging times. But not only energy density, also the battery lifetime is a key element and a minimum lifetime of 4000 cycles in an 80% DoD window in typical automotive conditions, over 10-15 years, is also the goal for new battery materials.

Li-ion batteries today exceed at least by a factor of 2.5 any competing technology thanks to the high value of energy density, i.e. 150 Wh/kg and 650 Wh/L. Although already in the market place, lithium batteries still require progress to meet the stringent requirements of the electric transportation market: e.g. increase of energy density and significant enhancement of service life on both cell level (standardization of cell design, cell chemistry, material costs) and battery level (module design, battery management system with active cell balancing, packaging, thermal management system) thanks to innovative materials and technologies and optimization of process characteristic.

Research and development activities within MARS-EV (Materials for Ageing Resistant Li-ion High Energy Storage for the Electric Vehicle) FP7 European project aims to overcome the ageing phenomenon in Li-ion cells by focusing on the development of high-energy electrode materials (250 Wh/kg at cell level) via sustainable scaled-up synthesis and safe electrolyte systems with improved cycle life (> 3000 cycles at 100%DOD). Through industrial prototype cell assembly and testing coupled with modelling, the understanding of the ageing behaviour at the electrode and system levels will be improved. Finally, it will address a full life cycle assessment of the developed technology.

The scientific and technological cooperation of the MARS-EV consortium covers the complete value chain from raw material processing, scientific comprehension, technological research and battery manufacturing. The research institutions (IK4-Cidetec, Helmholtz Institute Ulm, ENEA, CTP, Fraunhofer-ISE) and universities (Politecnico di Torino, Tel Aviv University, Imperial College, Oxford Brookes) provide complementary skills in new electrode and electrolyte materials, microstructural and electrical modelling and life cycle assessment. The industrial partnership combines specialty chemicals suppliers (Johnson Matthey, SGL Carbon, Solvionic) to battery manufacturers (Lithops, Cegasa), battery pack integrator (Johnson Matthey Battery Systems) and recycler (Recupyl).

An overview on the research and achievements during the first 6 months of the 48-month workprogram will be provided. The research lines followed include:

1. Synthesis of novel nano-structured, high voltage cathodes: LiFe_xMn_(1-x)PO₄ with in-situ Carbon coating; Mn, Co and Ni phosphates; Li-rich NMC with low Cobalt content.

2. Development of high capacity anodes: nanosized Silicon alloys (Si/C) and metal ferrites; protective coating to avoid degradation.

3. Development of green and safe, high-performing electrolyte chemistries: additives for safe high voltage cathode operation; ionic liquids; high conductive reinforced polymers.

4. Study of the ageing and degradation processes with the support of modelling, in order to improve the electrode and electrolyte properties and, thus, their reciprocal interactions and their effects on battery lifetime.

5. Realization of up to B5 format pre-industrial pouch cells with optimized electrode and electrolyte components and eco-designed durable packaging.

Acknowledgement: Project financially supported by the 7^th Framework Programme of the European Commission under Grant Agreement No. 609201.