New-Tech Europe Magazine | Jan 2018

this ‘pore confinement’, the properties of the bulk material are altered. Using this method we have been successful in developing a nano-composite electrolyte with a conductivity of a few mS/cm at room temperature. So this is more than enough to produce a high-capacity battery based on powder electrodes.” The powder-composite battery for large storage systems With this electrolyte, the researchers have reached the transition point and have started with the development of a solid-state powder-composite battery. In this battery, the electrode structures are much thicker (>70 micrometers) and as a result the battery capacity is much larger. The new electrolyte with an ion conductivity of over mS/cm means that the lithium ions are able to span the distances in and between the electrodes. Philippe Vereecken: “With this cell we are aiming at capacities in the order of Ah. This means they can be used in batteries for portable electronics (such as laptops or cameras), as well as for electric cars of the future, and in home storage systems for the electricity grid. By using solid-state batteries, this will enable us to offer a safer alternative to the ‘wet’ Li-ion battery. This will be a major asset for applications such as the electric car. It will also be possible to make these batteries more compact than the existing ‘wet’ Li-ion batteries and hence they will have greater energy den-sity.” To make this battery, the researchers follow as much as possible the same coating technology as that used in the fabrication of ‘wet’ batteries. Philippe Vereecken: “For the electrode coatings, micron sized active electrode particles are used. To increase the electronic conductivity through these porous elec-trodes, carbon is added. A binder polymer holds the active particles and the carbon in the electrodes together on a metal foil. After drying and compressing the electrode coating, the anode and

Fig 3: Charge/discharge performance of the powder-composite battery (full line). The capacity is 50% of the capacity for a similar cell with a liquid electrolyte (dotted line). Data have been measured by Xubin Chen (imec and KU Leuven).

The Author: Prof. Dr. Philippe Vereecken obtained his PhD in physical chemistry in 1998 from Ghent University. After seven years of experience in the US, first as a postdoctoral researcher at The Johns Hopkins University and then as Research Staff Member at IBM Research, he joined imec in 2005, working in the Nano-materials group. In 2010, he was appointed Associate Professor at the Center for Surface Chemistry and Catalysis, Faculty of Bioscience Engineering, KU Leu-ven. In the same year, Prof. Vereecken started up the energy storage activities at imec. At the present time, his work is focused on the development of solid-state Li-ion batteries.

cathode are brought together, with a po-rous membrane between them as separator. The assembled battery stack is then soaked with the liquid electrolyte so that it is present both inside the po- rous electrodes and inside the porous separator between the cathode and the anode layers. Our powder-composite battery is fabricated in a similar way. But now the nano-composite electrolyte is applied as a wet coating and then dried to obtain a solid-state electrolyte. We have built first demonstrators of this bat-tery, using LFP (LiFePO4) as the cathode and LTO or lithium metal as the an-ode. The electrodes were coated at JSR using their specific aqueous binder material. So far we are achieving 50% of the capacity for a similar cell with a liquid electrolyte.” In a next step, the capacity and rate performance will be improved. The development of the powder- composite battery is part of EnergyVille activi-ties, a center of expertise that unites KU Leuven, VITO, Hasselt University and imec for research into sustainable energy and intelligent energy systems. Philippe Vereecken: “Hasselt University and our affiliated lab IMOMEC there are also involved in this work. We will collaborate with them to continue research into powder coatings and electrode nano-particles. The next stage will be to upscale the technology. This will be done mainly in the new battery lab (with a dry room) that will be built in Genk as part of EnergyVille.”

Prof. Dr. Philippe Vereecken

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