Lithium batteries the cause of the recession?

Studies that used in the process of iron oxide electrodes, made from cheap non-toxic magnetite. Compared with the current electrode materials, magnetite transformational electrode materials such as (that is, and the reaction of lithium into new product), can store more energy, because they can hold more lithium ions. "However, the material energy storage capacity attenuation is very fast, and is dependent on the current density. For example, we of magnetite electrochemical tests show that the capacity of the magnetite fell sharply in the first 10 high-speed charging and discharging cycle." The study, functional nanomaterials, head of the center (CFN) electron microscope team leadership Dong Su said. CFN is located in the department of energy (doe) brookhaven national laboratory of science office user facilities.

In order to find out the cause of the cycle is not stable, the scientists are trying to watch, when the battery after a 100 - cycle, magnetite crystal structure and chemical changes. They combined with transmission electron microscope (TEM) and synchronous X-ray absorption spectroscopy (XAS), were studied. TEM of electron beam transmission through the sample, the material characteristics of the structure of the image or diffraction pattern, XAS use x-rays to detect the chemical properties of the material.

Scientists found that use of these technology for the first time is discharging, magnetite completely decomposed into metal nanoparticles and lithium oxide of iron. But in the charging process, this transformation is not completely reversible reaction, metallic iron and lithium oxide residues still exist. Magnetite, moreover, the original "spinel structure under the charged state of evolution for the" salt "structure (in two kinds of structure, the position of the iron atoms are not completely the same). In the subsequent charge and discharge cycle, lithium salt iron oxide and interaction, formation of lithium oxide and metallic iron nanoparticles composite material. Because the conversion is not completely reversible reaction, the residue will gradually accumulated. The scientists also found that the electrolyte (making lithium ion flow between two electrodes in the chemical medium) in the following loop will break down.