Inspenet, August 10, 2023.
The American company Amprius Technologies has presented the latest generation of a promising battery composition that aims to revolutionize various markets, from electric cars to vertical takeoff aircraft. These cells have a silicon anode with high density and discharge rate , which opens up new perspectives in the field of electrification.
In its most recent working prototype, Amprius has managed to achieve an energy density of 400 Wh/kg, which could represent a 50% improvement over the best cells currently available in full-scale production. In addition, they have managed to maintain their capacities even in discharge situations of up to 10 C (discharge time).
The particularity of this battery
This battery is based on a silicon anode, which is the positive electrode and can theoretically store up to 10 times more lithium than commonly used graphite. Furthermore, it achieves this capability with a higher level of safety against possible thermal runaways, even when faced with high power outputs.
Another notable feature of this model is that it can keep the output capacity unchanged even when the battery charge is at low levels. The company specifically notes that a set can withstand a power density of 3,000 W/kg at 30% depth of discharge, while the maximum power density could exceed 4,400 W/kg when load is high.
One of the fundamental keys to this system, which has been in development for almost a decade, is that Amprius was able to stabilize the silicon on the anode by silicon nanowires, overcoming the stability challenges associated with this element, such as its propensity to fracture and the consequent deterioration of the anode during charge and discharge cycles.
The nanowire structure made it possible to further exploit the potential of this material, which has a considerable capacity to accumulate lithium ions, increasing the capacity of the anode to 1,000 mAh/g compared to 372 mAh/g for traditional graphite anodes. . This makes it possible to considerably reduce the size of this component and, therefore, increase its specific energy capacity .
Amprius and the manufacture of silicon anode batteries
For several years, Amprius has been manufacturing these batteries on a limited scale, focusing on small electronic devices. Now, they are preparing to start production for vertical takeoff vehicles, which represent the main target market. Subsequently, they plan to expand into high-performance electric cars and competition vehicles.
This is just one of the open fronts to replace combustion engines and aviation engines and adds to the growing alternatives in the field, such as CATL cells with a promise of 500 Wh/kg or Li-S Energy cells. , which recently introduced third-generation cells with 20 layers and semi-solid state lithium sulfur technology, with a volumetric density of 540 Wh/l.