Scientists led by the University of Texas at Austin (UTA) claim that they have solved a mystery that has long plagued lithium-ion battery researchers and explained why some electrode materials show high energy storage capacity beyond physical possibilities.

Lithium ion technology has been responsible for changing the way we communicate and power our portable devices, and is now driving a revolution in global transportation and energy supply. Arumugam manthiram of the University of Texas at Austin published a new paper on the development of this technology, from the initial discovery in the 1970s to the consideration of researchers studying "future batteries" today.

Through cooperation with Qingdao University and Shandong University in China, Massachusetts Institute of technology and the University of Waterloo in Canada, the team was able to prove that several compounds based on transition metal oxides have three times the storage capacity of today, and explain a phenomenon that makes the capacity of these materials exceed their theoretical limits.

Yu Guihua, associate professor of UTA, said, "in the past two decades, researchers have been troubled by these abnormally high abilities that exceed the theoretical limit. This work proves the first experimental evidence that additional charges are physically stored in these materials through the space charge storage mechanism."

A paper published in the journal Nature Materials reveals that transition metal lithium-ion batteries have additional energy storage capacity by in-situ magnetic measurement, and its mechanism is described. The team proved that additional energy was stored on the surface of metal oxide due to the metal nanoparticles formed during battery discharge. These nanoparticles show strong surface capacitance and the ability to store a large number of electrons.

This phenomenon has been proved to be the main source of additional capacity of iron oxide electrode, and also exists in cobalt oxide and nickel oxide, iron fluoride and nitride. Although the understanding of the behavior of these materials in batteries is still limited, the team believes that their findings represent a major challenge for further development.

To observe the effect of this mechanism, they used a technique called in situ magnetism. This is usually used in physics to study charge energy storage at a very small scale, and relies on measuring changes in magnetism to quantify charge capacity. Associate Professor Yu Guihua said, "the most important result is obtained from the technology commonly used by physicists but rarely used in the battery industry. This is a perfect display of the perfect combination of physics and electrochemistry."

Article source:OFweek lithium grid