Imec, a research and innovation hub in nanoelectronics, digital and energy technologies and partner in EnergyVille—a collaboration between the Flemish research partners KU Leuven, VITO, imec and UHasselt—has developed a solid-state Li-metal battery cell with an energy density of 400 Wh/liter at a charging speed of 0.5C (2 hours).

Imec also announced that it has started to upscale the materials and processes in a pilot line for fabrication of solid-state pouch cells at the EnergyVille Campus in Genk (Belgium) and is set-up in collaboration with the University of Hasselt. With its engineering roadmap for solid-state batteries, imec aims to surpass wet Li-ion battery performance and reach 1000 Wh/L at 2-3C by 2024.

Today’s rechargeable Li-ion battery technology still has room for improvement, but not enough to significantly improve e.g. the range and autonomy of electrical vehicles. Therefore, imec’s researchers are working to replace the wet electrolyte with a solid material, which provides a platform to further increase the energy density of the cell beyond that of cells based on liquid electrolyte.

The solid nanocomposite electrolyte that the R&D center has developed has an exceptionally high conductivity of up to 10 mS/cm with a potential for even higher conductivities. A distinguishing feature of the new material is that it is applied as a liquid—via wet chemical coating—and only afterwards converted into a solid when it is already in place in the electrodes. That way it is perfectly suited to be casted into dense powder electrodes where it fills all cavities and makes maximum contact, just as a liquid electrolyte does.

Using that solid nanocomposite electrolyte in combination with a standard lithium iron phosphate (LFP) cathode and lithium metal anode, imec has now fabricated an improved battery with an energy density of 400 Wh/liter at a charging speed of 0.5C (2 hours)—a record combination for a solid-state battery.

With this result, imec managed to double its results of last year, following its roadmap to eventually reach densities over 1,000 Wh/liter at a charging speed of 2-3C (less than half an hour).

Volumetric energy density for selected cathode materials in full cell configuration with metallic Li as anode from a paper by BMW researchers published in Journals of Material Chemistry A in 2015. The different curves refer to different loadings. Calculation based on practical volumetric energy density values for the cathode. Yellow dots indicate for the various materials the typical coating densities nowadays achievable. Green bands: targets at cell level.

In addition, imec has commenced the upscaling of the cells in a state-of-the-art lab for this new solid-state battery technology, including a 300 square meter battery assembly pilot line which includes a dry room of 100 square meters. This conventional A4 sheet-to-sheet wet coating-based line is well suited for processing of imec’s innovative solid electrolyte.

As such, the assembly of the new cells could be done by slight modification of existing manufacturing lines for Li-ion batteries. This means the new technology would not need expensive investments to switch from wet to solid-state cells.

The new pilot line, which is located at the EnergyVille Campus, and is set-up together with the university of Hasselt, allows manufacturing of prototype pouch cells of up to 5Ah capacity. It is ready to become a cornerstone for research groups and companies doing R&D projects on these batteries.

Resources

• Dave Andre, Sung-Jin Kim, Peter Lamp, Simon Franz Lux, Filippo Maglia, Odysseas Paschosa and Barbara Stiaszny (2015) “Future generations of cathode materials: an automotive industry perspective” Journal of Materials Chemistry A doi: 10.1039/C5TA00361J