Belgian research group says it has produced a functional solid-state battery with an energy density of 200Wh/l
Belgium-headquartered research and innovation group imec says it has taken a major step forward in its development of a next-generation solid-state battery.
imec reports that its researchers have successfully built a solid-state li-ion battery with an energy density of 200 Wh/litre, and capable of a charging speed of 0.5 coulombs (i.e. a recharge time of 2 hours).
Solid-state batteries are considered to be safer than conventional liquid-electrolyte cells, in that they are tend not to use flammable chemicals. Their construction also precludes the formation of dendrites – finger-like deposits of lithiated metal which can build up to cause short circuits.
From a performance point of view, they also possess a greater energy density, making them an important target for EV battery makers.
imec says its system is based on a solid nanocomposite electrolyte it recently developed, which shows an “exceptionally high conductivity” of up to 10 mS/cm, a figure which could be increased further.
To produce the battery itself, this super-conductive electrolyte was poured into the cell as a liquid precursor, and then solidified. This allows the liquid to fully fill the cell, reaching into all cavities and maximising contact between the solution and the porous electrodes. Once set, imec says the electrolyte remains slightly elastic, allowing it to change shape over cycling, and extending the lifetime of the cell.
The resulting prototype using this solution achieved a volumetric energy density of 200 Wh/litre.
You can view a video of the production process below:
Crucially, the fact that the electrolyte is introduced as a liquid also means that the whole process remains compatible with current battery production techniques – the inference being that factories would not have to completely retool their production lines to incorporate the new technology.
Under its development roadmap, imec says it intends to surpass liquid li-ion battery performance and reach a solid-state energy density of 1,000 Wh/l at 2C by 2024. This would see the technology “ready to become a contender to power tomorrow’s fast-charging, long-haul vehicles,” it added.
The group’s principal scientist and program manager Philippe Vereecken notes:
“Our results show that we can make solid-state batteries that have the potential to reach the capabilities of wet batteries, and this using manufacturing processes similar to those for wet batteries. But unlike wet-batteries, our solid-state batteries will be compatible with metallic lithium anodes with a target of 1,000Wh/liter at a charging speed of 2C (half an hour). This, together with their longer lifetime and improved safety, makes them a promising compact battery technology for tomorrow’s long-range vehicles.”
The team is examining the combination of nanoparticle electrodes with this solid nanocomposite electrolyte. Here, ultra-thin coatings are used as so-called buffer layers to control the interface between the electrode and electrolyte – this technology could be used to improve the performance of current liquid cells and even for all-solid-state batteries with pressed and sintered inorganic electrolytes.
The group concluded by affirming that its battery R&D programmes rely on collaborative efforts with material suppliers and battery producers, and that it invites any and all interested parties to participate. With extra input from other battery innovators, perhaps that 2024 target can be reached even earlier.