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

Project Information

SOLiDIFY

Grant agreement ID: 875557

DOI

10.3030/875557

Project closed

EC signature date 14 November 2019

Start date 1 January 2020

End date 30 June 2024

Funded under

• INDUSTRIAL LEADERSHIP - Leadership in enabling and industrial technologies - Advanced materials

Total cost

€ 7 823 927,50

EU contribution

€ 7 823 927,50

Coordinated by

INTERUNIVERSITAIR MICRO-ELECTRONICA CENTRUM
Belgium

Periodic Reporting for period 3 - SOLiDIFY (Liquid-Processed Solid-State Li-metal Battery: development of upscale materials, processes and architectures)

Reporting period: 2023-01-01 to 2024-06-30

Summary of the context and overall objectives of the project

The push towards reducing carbon emissions and combating climate change has led to a surge in electric vehicle (EV) adoption. However, the drive for extended range and faster charging times highlights the ongoing need for high-performance batteries. At the same time, it’s crucial to ensure these batteries are cost-effective, as they currently account for nearly half the price of an EV. Thus, the materials used in these batteries play a key role in determining both their performance and affordability.
Enter solid-state batteries. These batteries use a solid electrolyte material through which ions flow to charge and discharge, instead of the liquid electrolyte used in conventional lithium-ion batteries. This offers potential benefits such as higher energy density and reduced susceptibility to fires. At the material level, the higher energy density of the cell results from the introduction of a thin lithium metal anode together with a sufficiently thin solid electrolyte component. However, developing a cost-effective architecture for their mass production has remained elusive.
Now, within the SOLiDIFY project, imec and its 13 European partners have created a prototype of a high-performance lithium-metal solid-electrolyte battery.
The pouch cell, manufactured in the state-of-the-art battery lab of EnergyVille (Genk, Belgium), achieved an exceptional energy density of 1070 Wh/L (940Wh/L actual at C/3 charging at 70 degrees C, at C/10 charging at 40 degrees C), compared to the maximum of 800 Wh/L for lithium-ion technologies. A cyclability of 100 cycles at 80% of SOH was shown.
Importantly, with a manufacturing process that is manageable at room temperature, adaptable to current lithium-ion battery production lines and projected to cost less than €150 per kWh, this process holds promise for affordable industrial transfer.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

To achieve the exceptional energy density of 1070 Wh/L, several critical steps needed to be taken regarding the materials and processes.
A second generation SOLiDIFY solid composite electrolyte (SCE) separator was developed by adding an optimized filler content of ceramic nanoparticles in the SCE precursor solution. The resulting separator had excellent mechanical properties, ionic conductivity (1.4 mS cm−1), anodic stability (> 5 V vs. Li+/Li), and compatibility with lithium metal. Moreover, a novel type of hybrid SCE, which combines functional properties with electrode compatibility and manufacturability was presented. It consists of liquid precursor solutions with indefinite stability which can be triggered to cross-link by rapid photo-initiated radical polymerization, effectively creating an organic-inorganic hybrid solid-state electrolyte.
Regarding the cathode, new architectures enabling thick layers with high loadings were introduced, an essential step to realize batteries with high energy densities. Three types of nm-thin barriers were evaluated as coating for the cathode particles themselves and proved to be effective in enhancing their long-term stability when in contact with the applied electrolytes. A process to effectively impregnate the cathode with the solid electrolyte was realized.
On the anode side, advanced coatings and roll-to-roll processing techniques enabled the use of thin lithium metal anodes at higher current rates without potential hazards. Thin uniform coatings of polyethylene oxide or a polymerised-ionic-liquid proved to protect Li-on-Cu foils. Also with N2-treatment and LiPON depositions, performance of Li anodes could be improved.
The resulting cells did not only demonstrate high energy density, also regarding device safety the project pushed the boundaries. Safety tests (e.g. nail penetration, thermal, overcharge) performed on the developed prototypes validated the concepts of the solid-composite electrolytes and their lower flammability.
While every partner will have their own exploitation, the collaboration of the partners lead to a doped polymerized ionic liquid (PIL)-based nanocomposite material and a high-capacity composite cathode, separated from a thin lithium metal anode by a thin solid electrolyte separator (50 μm), both essential.
The results will land in SOLiTHOR, a spin-off of imec, and in VDL’s new battery centre in Born (NL).
During the project 2 patents were granted (to imec and UHASSELT and to EMPA), both in the EU as well as in the US.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The mission put forward by SOLiDIFY project was to develop next generation safe and high performing, cost-effective and environmentally sustainable battery prototypes by novel materials and up-scalable manufacturing process. Several research projects and industries have developed high performing soli-state batteries targeting energy densities of 800-1000 Wh/L, with key advancements focussing on utilizing solid electrolytes such as sulfide, oxide and polymer-based materials to prevent the dendrite formation against Li anode, improve cycling stability against high-voltage cathodes, and enhanced safety by replacing flammable liquid electrolytes. The state-of-the-art lithium-ion batteries could deliver energy density of maximum 800 Wh/L, whereas the unique materials and upscalable-processing technologies aimed to push the boundaries of solid-state lithium metal batteries demonstrating higher energy density up to 1070 Wh/L, a gravimetric energy density of 352 Wh/kg, long-term cyclability, higher intrinsic safety, and a cell cost of 130 €/kWh. These numbers were achieved with 0,1Ah pouch cells.
The consortium adopted low-cobalt content active materials, which significantly enhanced the sustainability of the prototypes by reducing dependency on critical raw materials, facilitating easier recycling, and lowering environmental impacts associated with cobalt mining. The reduced cobalt content minimised the toxic waste generation and led to a more environmentally friendly life cycle for solid-state batteries. In parallel, SOLiDIFY developments were conducted with full Life Cycle Analysis to ensure that a positive environmental impact was achieved with the developed technologies and processed materials. In addition to the assessment, a recycling scenario for the SOLiDIFY cell was proposed to recover the electrode and electrolyte materials used within the project.
The new methodologies and characteristic techniques developed for solid-state-lithium metal batteries as part of the project contributed to strengthening the expertise of the partners, enhancing longer-term capabilities and thus fuelling the EU modelling ecosystem. Advanced materials and pouch cell assembly processes were developed and (some) protected as patent applications to strengthen the patent portfolio of the partners and their position in the market. Such advancements were identified as key exploitable results (KER), which were reviewed and consolidated into 20 KERs. The SOLiDIFY projects’ vision was to contribute to the European society by strengthening the European battery value chain through the development of a competitive and sustainable battery cell in Europe. In addition, the project aimed to enable the development, in Europe, of a gender-diverse, highly qualified work force skilled in the latest battery materials and technologies.

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