SAFT completed the manufacturing and the deliveries of the large solid-state pouch cells for testing by partners till the end of the project.
Based on the pre-industrial large pouch cell format developed in SAFT, the demonstration of the manufacturing feasibility of the SAFELIMOVE large all solid-state pouch cell has been successful. Once manufactured, those large pouch cells have been electrochemically characterized during the formation stage and shipped to partners for electrical and lifespan evaluation. In addition, six cells are integrated in the 24V battery module demonstrator developed by IKERLAN.
Thanks to the feedback and know-how gained, with the manufacture of small-scale 1Ah pouch, SAFT has developed an innovative assembly process methodology for the manufacturing of this final 3Ah prototype pouch cell.
- Objective: To do so, the required cell components were manufactured and sent to SAFT:
– Very thin self-standing lithium metal foil (40 µm) manufactured by HYDRO-QUEBEC.
– High loading solid-state cathode (loading 2,6 mAh/cm2) manufactured by CIDETEC with lithium nickel manganese cobalt oxide (NMC811) from UMICORE.
– Solid electrolyte layer (thickness 70 µm) prepared by SAFT, made of polymers provided by CIC Energigune and inorganic filler (LATP) provided by Schott.
- Research: Numerous manufacturing trials have been performed to define, scale-up and fine-tune the final assembly protocols and the related parameters. During the scale-up study, the focus areas were on specific topics related to the SAFELIMOVE SSB technology such as:
- Handling and stacking techniques of LiM (Lithium Metal) and SEL (Solid Electrolyte Layer).
- Ultrasonic welding of the tabs to the very thin LiM anode stack.
- Smoothing operation for optimal electrolytic contact between electrodes and SEL.
Once manufactured, these 3 Ah pouch cells were checked electrochemically (internal resistance, cell capacity) to validate their performances prior packaging and shipment to the partners.
- Result: the 3 Ah pouch cells have been successfully manufactured, demonstrating the technical achievement for a Milestone, reached in June 2023 (1st batch of cells). The final cell capacity obtained is in coherence with the expected capacity. The cell performances have shown dispersions which demonstrate good manufacturing reproducibility. Within a very leadtime, a total of 12 cells have been delivered.
The gravimetric energy density for these GEN1 cells has been set at 50% of 450Wh/kg. Using the Level 2 materials, these 3 Ah pouch cells achieved ca. 260 Wh/kg (60°C; C/20; stack level).
The main limitations and challenges in the manufacturing of these large-scale cells are the manual handling and the transfer of the anodes and SEL between the process steps. For large scale SSB production perspective, the industrialization of the SAFELiMOVE technology will require improvement of the process to make the manufacture possible by automated equipment, such as :
- The processing of the anode based on this very thin LiM roll
- The processing of the SEL by roll-to-roll coating and cross-linking,
- The stacking technique of electrodes and SEL (Z-fold or alternatives).
- Impact: The successful manufacture of these large prototype pouch cells provided an important input on all the production chain of solid-state batteries. From this experience, key issues during SSB manufacturing process have been identified and solutions for large-scale battery production have been suggested and shared in SAFELiMOVE.