The semi-solid electrode uses an innovative method that does not use binders, mixing electrolyte with active materials to form a clay-like slurry. This electrode slurry makes the electrodes thicker, lighter, and less expensive while simplifying the manufacturing process. This semi-solid electrode is very flexible and can be used with many different materials, including silicon.
One project aims to combine lithium metal anodes and semi-solid cathodes for applications in electric aviation. The project also includes the development of a commercial, modular pilot production line that can be scaled up to series production.
Another interim approach is to use silicon anode technology that has been proven in current commercial batteries. Batteries already in production have an energy density of 450 Wh/kg and a capacity of 20 Ah, while batteries about to enter production will have an energy density of 800 Wh/kg.
However, the challenge with silicon technology is that when charging, the anode expands three times, causing the battery to crack and leak. Although a lot of work has been done to minimize this problem, it can be avoided by using solid electrolytes.
There are other techniques used to increase the capacity of existing batteries, such as using three-dimensional structures in positive copper foil or aluminum foil, which can also be applied to solid-state batteries.
In Chinese electric vehicle manufacturer NIO’s ET7 150 kWh battery pack, semi-solid electrodes and polymer electrolytes with high nickel content are used. The battery pack will go into production at the end of 2022. This battery pack uses interface engineering technology to achieve stable cycling of lithium polyethylene oxide polymer electrolyte, using a cathode containing 50% nickel, 20% cobalt and 30% manganese to produce a voltage of 4.2 V, while the carbon-silicon anode also Contains lithium. This battery has an energy density of up to 360 Wh/kg, a cruising range of more than 1,000 kilometers, and supports fast charging.