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Liquid-Processed Solid-State Li-metal Battery: development of upscale materials, processes and architectures

Periodic Reporting for period 2 - SOLiDIFY (Liquid-Processed Solid-State Li-metal Battery: development of upscale materials, processes and architectures)

Reporting period: 2021-07-01 to 2022-12-31

In the context of fighting against climate changes and global warming, worldwide efforts towards the reduction of CO2 emissions are pushing towards a rapid implementation of electrification of transportation. A steep deployment of battery electric vehicles (BEV) is expected in the coming decade. However, to convince the average consumer to buy electric, and thus enable a reduction of greenhouse gas emission, the electric vehicle should be affordable, safe and with the comfort of large enough driving range and short enough charging time. Those four key requirements are directly linked to the performances of the battery cell, a key component in the Electric Vehicle (EV). Current battery cell technologies are reaching their limits. A main difficulty lies in increasing further the driving range and decreasing the charging time, while maintaining a safe operation of the cell and EV. The SOLiDIFY solid-state battery concept and its unique solid electrolyte component can offer a solution for most shortcomings in battery technology including upscaling and manufacturing at an affordable cost. From a safety point of view, we expect an increase of the safety features of the cells by replacing the conventional liquid flammable electrolyte used in today’s battery by our new thermally stable and non-flammable solid state electrolyte.
The main objectives described in the project proposal are still accurate and extremely challenging as described below:
Today’s electric vehicles are equipped with lithium-ion battery cells that can deliver a little less than 700 Wh/L (230 Wh/kg) and thus a significant boost in performances is still needed while safety of the cells should remain ensured. A range of 700 km is considered a turning point in consumer interest. To reach this driving range, cells of > 900 Wh/L (> 500Wh/kg) will be needed. SOLiDIFY plans to demonstrate two generations of solid-state battery cells reaching 900 Wh/L and 1200 Wh/L, respectively.
In terms of charging time, customers expect to be able to recharge partially their battery in less than 20 minutes, which we set as a target to recharge our solid-state battery cells.
Finally, while current Li-ion battery cell cost is nowadays on average > 125 €/kWh, it is a project objective to achieve a manufacturing and material strategy to reach the cost target of < 100 €/kWh. Overall, the project comprises the development of a manufacturable solid-state battery technology based on a unique liquid-to-solid processed solid electrolyte which is easily impregnated into the electrodes providing multiple advantages towards cell performance and upscale manufacturing both directly in relation with the cost of the cell (€/kWh). The wider scope of the SOLiDIFY project entails the development of a novel and potentially European-lead solid-state battery technology and specifically targets upscaling of the processes and cells from demonstrated concepts in the lab to prototypes demonstrated in a pilot line environment.
Since the beginning of the project, the 14 European partners of the Solidify consortium have worked hand in hand towards the development of the various separate components to be integrated together into the first cell prototype, expected to be ready at month 40 of the project, towards the following intermediate target performances: 900 Wh/L, charge in 40 min and having a lifetime > 500 cycles.
Over the last 18 months, the different key components towards Gen S2 demonstrators have been developed, characterised, and assessed separately:
i) advanced cathode architectures (open current collector, single-step and trenched) incorporating NMC622 and NMC811 positive electrode(s) (cathode) consisting of these active material particles covered with a new thin coating and deposited on a current collector made of a thin (10 µm) aluminum foil (Umicore, Delft-IMP, Fraunhofer, imec, TU-Delft)
ii) advanced PIL-based solid electrolyte separator sheet being mechanically stable, thin, and conducting the Li+ ion at room temperature (imec, Solvionic, Empa), which can also be infiltrated into NMC cathodes. The addition of additives (imec) has been evaluated, further improving the mechanical strength and ionic conductivity and allowing the attainment of 100% areal capacity of partner cathodes (NMC622@TiO2).
iii) new group of advanced negative electrode(s) (anode) consisting of protected thin Lithium metal anode (Sidrabe, EMPA, imec, TU-delft) based on nitrification and PIL coatings on 20 µm Li metal on 10 µm Cu foils.
In addition, initial integration works have taken place under the coordination of imec and Fraunhofer, with the first Gen S1 (3×5) cm2 pouch cell assembled and upscaled components received ready for integration into (10×15) cm2 pouch cells at Fraunhofer.
A new cell was specifically designed by UHasselt to test solid-state battery cell and component performance as a function of temperature and pressure. Initial results on the newly developed solid-state electrolyte membrane were collected, and now directed towards PIL-based SCEs.
In concertation with all partners, the cell specifications, requirements, and testing protocols have been developed by the cell manufacturer and equipment supplier (Leclanché, Solith) and end users (CRF, VDL), respectively. Furthermore, pouch cell process flows have been developed and adapted according to the handling and requirements of the developed components, and communicated to all concerned partners. In parallel, the preparation work for the Life Cycle Analysis and cost analysis of new solid-state battery cell started (Gemmate, Leclanché), with requested data from all partners communicated and delivered to Gemmate for the preparation of the LCA for Gen S1 demonstrators.
SOLiDIFY will deliver prototypes of the next generation solid state battery cell demonstrating higher performances (high energy density up to 1200 Wh/L, shorter charging time, higher intrinsic safety) than current Li-ion battery cell. A competitive cycle life (> 1000 cycles) and cost (< 100 €/kwh) of those new cells are expected.
Advanced materials and assembly processes have been, and continue to be, developed and (some) protected as patent applications to strengthen the patent portfolio of the partners and their position in the market. Such advancements are identified as key exploitable results (KER), which have recently been reviewed and consolidated into 20 KERs.
New models, methodologies and analysis techniques specific for Solid State Battery have been developed as part of the project and will contribute to strengthen the expertise of the partners, strengthening longer-term capabilities and thus fueling the EU modeling ecosystem. In parallel, SOLiDIFY developments will be conducted with full Life Cycle Analysis to ensure that a positive environmental impact is achieved with the developed technologies and materials. Environmental impact assessment of the full life cycle including recycling started, and is ongoing. Beside contributing to the preservation of the environment, the SOLiDIFY projects’ vision is to contribute to the European society via the strengthening of the European battery value chain through the development of a competitive and sustainable battery cell in Europe. In addition, the project aims to enable the development, in Europe, of a gender-diverse, highly qualified work force skilled in the latest battery materials and technologies.