MIT Develops New Ionic Liquids To Improve Supercapacitor Performance Or Replace Supercapacitors With Batteries

- Sep 20, 2019-

According to foreign media reports, a supercapacitor is an electronic device capable of storing and releasing energy, having a layer of electrolyte - a conductive material that can be solid, liquid or between solid and liquid. Now, the Massachusetts Institute of Technology (MIT) has worked with several agencies to develop a new type of liquid that may increase the efficiency and stability of such equipment while reducing flammability.

The researchers say the study may represent a new paradigm for electrochemical energy storage. A few decades ago, researchers have discovered a new material - an ionic liquid (essentially a liquid salt), but the team added a compound to the ionic liquid that is surface active with the oil used to disperse the leak. The agent is similar. After the addition of the compound, the ionic liquid "has a very novel nature and becomes very viscous." The researchers said: "It is difficult to imagine that this viscous liquid can be used to store energy, but we found that once the temperature is raised, Liquids can store more energy, and more energy is stored than many other electrolytes."

But in fact, this is not very surprising, because other ionic liquids will decrease in viscosity with increasing temperature, and the ability to store energy will also increase. However, the current situation is that although the ionic liquid is still higher in viscosity than other known electrolytes, its capacity still increases rapidly with increasing temperature, and finally its overall energy density exceeds the energy density of many conventional electrolytes, and Stability and security are also higher.

The liquid's efficient energy storage capacity is derived from the fact that the molecules inside it are automatically aligned, eventually forming a layered structure on the surface of the metal electrode. One end of such a molecule has a tail that is aligned with the head or toward or away from the electrode, while the tail gathers in the middle to form a sandwich-like structure called a self-organizing nanostructure.

This highly ordered structure prevents the appearance of "transitional filtration", which can occur in other ionic liquids. When it occurs in other ionic liquids, the first layer of ions (charged atoms or molecules) accumulated on the surface of the electrode contains more ions than the corresponding charges on the surface, resulting in a more dispersed ion distribution or a thicker ion layer. , resulting in inefficient storage. However, due to the special structure of the liquid made by the researchers, the charge is concentrated on the surface of the electrode.

Researchers refer to this new material as SAILs, surface-active ionic liquids, which have many applications for high-temperature energy storage, such as in high-temperature environments such as oil drilling or chemical plants. “Our electrolytes are very safe at high temperatures and perform better. In contrast, some electrolytes in lithium-ion batteries are very flammable.”

The researchers said the material could help improve the performance of supercapacitors. Supercapacitors can be used to store electrical energy, sometimes in addition to electric vehicle battery systems, to provide additional power to electric vehicles. Compared to conventional electrolytes, the energy density of supercapacitors using this new material is increased by 4 to 5 times. Compared to batteries, with new electrolytes, future supercapacitors may be able to store more energy and may even replace batteries in applications such as electric vehicles, personal electronics or grid-level energy storage facilities.

In addition, the material may be used in a variety of emerging separation processes. Many newly developed separation processes require electrical control, such as capturing carbon dioxide and recovering resources from waste, and other chemical processing and refining applications, and such highly conductive ionic liquids are well suited for such applications.

The material originally developed by the researchers is only one of the possibilities for SAIL compounds, and the team will continue to develop different possible compounds and optimize parameters for specific uses.