Anode Development: Anodes have been developed by UL and Smit Thermal consisting of amorphous silicon deposited onto current collectors consisting of copper silicide nanowires grown from a copper foil. The porosity of the amorphous silicon anode coating was controlled by Smit Thermal through the hydrogen source content. Anodes have been prepared in large areas (6 x5 cm) and tested with ionic liquid electrolytes and in full cells versus high voltage lithium rich cathodes.
Electrolyte Development: Overall WP2 target is the development of high purity, anhydrous, ionic liquid-based electrolytes, both liquid (Gen 1) and solid (Gen 2). The former will be housed within proper polymer hosts. The developed electrolyte systems have to match the following targets: extremely low volatility, non-flammability, high conductivity (> 1 mS cm-1 at 20 °C and > 0.1 mS cm-1 at –10 °C), high anodic stability (> 4.5 V (vs. Li+/Li°), high thermal stability (> 150 °C), good compatibility (in terms of cycling performance) with large capacity silicon anodes and high voltage lithium-rich nickel manganese oxide cathodes, industrial up-scalability. Finally, proper amounts have to be provided for the prototype manufacturing.
Within WP3 of Si-DRIVE new LRLO cathode materials are developed with the primary goal to eliminate Co from the structure. In order to subsequently further improve the performance of the material, i.e. avoid structural decay and the corresponding fading of capacity and voltage, specific dopants are introduced to stabilize the Li-deficient layers at high state of charge. Finally, protective coatings are investigated to avoid the transformation starting from the surface into the bulk structure, as well as to prevent oxidative decomposition of the electrolyte at high potentials allowing the use of ionic liquids and to enable the aqueous electrode processing of the LRLO cathodes.
WP4: From the beginning of the project, aqueous-based Gen0 and Gen1 Li-rich layered oxides (LRLO) cathodes were processed and characterised, showing comparable electrochemical performance to electrodes prepared from conventional organic based slurries (NMP as solvent). Full cell characterisation of SI-DRIVE chemistry resulted on cells with a cycle life of 200 cycles > 80%SOH with areal capacity of 1.5 mAh/cm2. The most suitable components were identified for Gen1 prototype pouch cells: organic LRLO cathode, Si/Gr anode and carbonate-based electrolyte.
Component Modelling: On the cathode side, a computational description of the structure, the electronic properties and the thermodynamic and structural stability of cathode materials based on LRLO oxides (with formula Li1.2Ni0.2-x/2Mn0.6-x/2CoxO2 where x= 0.12 0.08 0.04 and 0) was developed by means of DFT calculations.
End of Life, LCC & LCA: So far there are no pouch cells available for post-mortem analysis and aging analysis in 6.3. First investigations, performed on cycled cathode materials (from coin cells) show structural degradation. Driving profile (by CRF) on fast charge was tested in coin cell format at CID. 1 kg of LRLO material was synthesized for RWTH Aachen for starting recycling activities.
Project Dissemination, Exploitation, Communication & Management: Exploitable results were identified in each work package. From a management point of view, activities continued on the project via a specialist EU project manager.
