The first activities were dedicated to identifying initial specifications for the batteries that will be manufactured in the SOLiD project. Preliminary calculations of energy density and dimensions of the cells for the automotive application of the SOLiD technology were proposed. In details requirements for: i) the size, safety, and performance of the SOLiD battery prototypes, including pouch cell design; ii) the processing of the battery cell layers; iii) the materials and interface development; iv) the inline inspection and data handling; v) the cost and sustainability.
On the negative electrode side (metallic lithium), Pulsedeon has set up a process for producing Li-metal layers by PLD. Li layers of 3 and 10 µm in thickness have been produced on Cu substrates. In addition, Aalto university has screened and tested different protective layers on the Li metal to enhance its stability, processed by atomic layer deposition (ALD).
On the positive electrode side (NMC811), Aalto university has screened and tested different ALD coated protective layers on the cathode active material powder. The obtained coated electrodes were further exposed to galvanostatic charge-discharge cycling in Li half-cells (CR2016) filled with liquid electrolyte. In addition, Specific Polymers has provided a few different polymer electrolytes to VTT, and VTT has used those to optimise the dry extrusion process for the cathode composite layer in lab-scale. Armor Battery Films has provided current collectors coated with different primer layers for these tests. The extruded electrodes have been analysed by adhesion tests at Armor Battery Films and at VTT by electrochemical tests in half cells and liquid electrolyte.
Regarding the polymer electrolytes (to be used as the binder and the separator), Specific Polymers has synthetised and optimised the materials to match with the project objectives regarding e.g. the ionic conductivity and electrochemical stability window. CSEM and TBU have tested and optimised these electrolytes in test cells. Aalto university supported this activity by providing cross-section images of the extruded samples, containing NMC mixed with the electrolyte. In addition, CNRS has also worked to test and design polymeric interlayers to be used as a smart binder for maintaining a permanent electronic conductive path during volume expansions and contractions due to battery operation.
The inline inspection and quality control activities have been focused on developing sensors at BFH, VTT, CSEM and Coatema for the supervision of the SOLiD manufacturing process and for later use in a digital twin and feedback loops. Additionally, the work on the digital twin has been initiated a bit ahead of plan.
