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New technology increases lithium battery power by 3 times
- Jun 28, 2018 -

Recently, the University of Maryland and the National Laboratory of the Department of Energy collaborated with U.S. military researchers to develop a new type of cathode nanomaterial lithium battery whose energy density has reached three times that of existing commercial lithium batteries. The research results were published in Nature Communications. "Journal.

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With the increasing application of lithium batteries, the demand for high energy density batteries is also increasing. However, in a conventional commercial lithium battery, the anode material is usually a good conductive material such as graphite, but the capacity of the cathode material is very limited. Fan Xiulin, a researcher at the University of Maryland, one of the main authors of the paper, said that “cathode materials are the bottleneck in lithium battery research. It is very difficult to increase the energy density of batteries based on this.”

To solve this problem, researchers from several U.S. agencies have synthesized an engineered iron trifluoride (FeF3) with higher energy density and environmental friendliness.

In fact, iron trifluoride has not been used as a cathode material for lithium batteries. When an electrode reaction takes place, the iron trifluoride gains electrons from lithium and converts it into iron and lithium fluoride. Due to the hysteresis effect of this compound, the rate of reaction in the electrode is low, and the reaction by-product will also hinder the electrode reaction from proceeding. In addition, this reaction is not completely reversible, which means that the number of reaction cycles of the iron trifluoride electrode is very limited, and the economic performance of the battery is greatly reduced.

In response to these problems, the researchers discovered a mechanism of this electrode reaction from a microscopic level through extensive experimental studies. Using transmission electron microscopy (TEM), the researchers determined the true size of the cathode nanomaterial and observed structural changes during its charge and discharge.

Since then, the researchers used X-ray powder diffraction (XPD) technology to observe the crystal structure in the nanorods, and found that adding other atoms can effectively increase the reaction rate. Therefore, the team used chemical substitution methods to add cobalt atoms and oxygen atoms to the iron trifluoride nanorods, which changed the reaction mechanism, so that the electrode reactions of the iron trifluoride became reversible and the battery life was greatly increased.