Researchers from the Department of Materials Science and Engineering at the Korea Advanced Institute of Technology (KAIST) have created a hybrid solution using a sodium-ion battery as a basis. The choice of sodium in the long term is obvious - there is a lot of it and it is a cheap raw material.
The Koreans are not the first to develop sodium-ion batteries. But they went further and tried to combine the best technologies of lithium batteries and supercapacitors into new batteries that have a unifying capacity, power density and charging speed.
The scientists reported their new development in the journal Energy Storage Materials. The title of the article says it all: “Polyvalent iron sulfide with low crystallinity, conductive anode with additive and high-sodium 3D porous graphitic carbon cathode for high-efficiency sodium-ion hybrid energy storage devices.“
It is clear that you cannot simply take and combine anodes from conventional batteries and cathodes from supercapacitors in the new device. It is necessary to change the properties of both the anodes and the cathodes. The former have a poor charging speed, while the latter do not have a high capacity.
Therefore, scientists are embarking on the path of creating volumetric electrodes based on porous 3D materials - the so-called metal-organic frameworks. If there is a framework, you can always put something you need in it.
Thus, researchers create an anode by incorporating finely divided active materials into porous carbon (MO-framework). The resulting material has the highest kinetics, allowing for fast charging and bringing it closer to supercapacitors in this parameter.
In a similar way, but with other materials, a cathode with a record capacity was created. Thus, the scientists appear to have reduced the imbalance in the characteristics between the anodes of the battery and the cathodes of the supercapacitor.
The laboratory's prototype sodium-ion hybrid battery outperforms the familiar lithium-ion batteries in energy density and exhibits the power density characteristics of supercapacitors. This solution is expected to be suitable for fast-charging applications ranging from electric vehicles to smart electronic devices and space applications.
The scientists also noted that the sodium-ion hybrid energy storage device, capable of fast charging and achieving an energy density of 247 Wh/kg and a power density of 34,748 Wh/kg, represents a breakthrough in overcoming the current limitations of energy storage systems and is a truly impressive discovery.