research & development

MIT Turns Snails and Shells into Batteries

The Massachusetts Institute of Technology is touting the work of a research team led by Angela Belcher that has helped turn studies of sea snails and their shells into a new nano-materials-based battery technology. Belcher, the Germeshausen professor of materials science and engineering and biological engineering at MIT, has developed a material that combines organic and inorganic parts to create a film that resembles plastic food wrap.

Belcher created a nanoscale rechargeable battery composed of a virus that she and her colleagues engineered to attach to cobalt oxide. The resulting film is transparent and efficient, according to MIT, and could be applied as a coating on whatever object it's powering.

She conducted the research with well-known MIT researchers: chemical engineering professor Paula Hammond and materials science professor Yet-Ming Chiang, co-founder of Westborough-based American Superconductor and Watertown-based A123Systems.

Belcher founded Cambrios Technologies Corp., a Mountain View, California, company, which has the rights to her "directed evolution" virus technology and is looking at the developments.

Germans Developing Perpetual Battery

Researchers in Germany are developing a revolutionary new battery that never needs recharging. Mobile phones, notebook computers and iPods are all devices dependent on rechargeable lithium-ion batteries to deliver power.

But the German researchers have developed a new class of inorganic ionic conductor with a structure analogous to that of the mineral argyrodite.

A team led by Hans-Joerg Deiseroth in Siegen, Germany, reports in the journal Angewandte Chemie the characterization of the most conductive representative of the man-made argyrodite minerals made of lithium, phosphorus, sulphur and bromine atoms.

In ionic conductors, charge is not transported in the form of electrons as it is in metals. Instead, the charge is transported in the form of charged particles, typically lithium ions. This transport requires materials in which the lithium ions can move as freely as possible.

The team from the University of Siegen, in cooperation with scientists at the University of Muenster, started from a long-known mineral: argyrodite, a silver, germanium and sulphur-containing mineral discovered near Freiberg, Germany, in 1885. The silver ions in this material are very mobile.

The individual components of argyrodite can be replaced by a number of other atoms without altering the typical structure of the mineral, according to a report on the physorg.com website. The term argyrodite now refers to an entire class of compounds that have a specific arrangement of atoms and type of structure.

The team led by Deiseroth produced a version of the mineral in which silver is replaced by lithium, germanium by phosphorus, and some of the sulphur atoms by halides (chloride, bromide or iodide), resulting in argyrodite-like structures.

In the crystal lattice the phosphorus, sulphur and halide atoms adopt a dense tetrahedral packing arrangement in which the gaps are filled somewhat regularly with lithium ions. The lithium ions can "jump" from gap to gap, said the report by physorg.com. The freely-moving ions indicate that the solid has a high ionic conductivity and the reported bromine-containing structure has the highest ionic conductivity of lithium ions known for any argyrodite.

The scientists have thoroughly examined the lithium argyrodites by single-crystal X-ray crystallography and nuclear magnetic resonance spectroscopy. This analysis allowed precise characterization of the crystal structures of these compounds and provided insights into the dynamics of the mobile lithium ions.