News

Better batteries from lithium images

Sept. 4, 2003

Researchers at the Massachusetts Institute of Technology (MIT) have captured the first images of individual lithium atoms

Sherri L. Koucky

. The research team used a transmission-electron microscope to simultaneously resolve columns of lithium, cobalt, and oxygen atoms in the compound lithium-cobalt oxide (LiCoO2). LiCoO2 is commonly used in the positive electrodes of lithium rechargeable batteries. MIT is interested in seeing the atoms and the vacancies left by moving ions arranged in 3D as a prerequisite to improving rechargeable batteries.
Michael O'Keefe, Materials Sciences Div. staff scientist at the Lawrence Berkeley National Laboratory, says a computer simulation predicted that columns of oxygen atoms should look bright and sharp-edged, the cobalts should be fuzzy, and the lithium should be small and look a little stretched. Researchers took the experimental images and worked backwards to produce a representation of the electron wave leaving the exit surface of the specimen. This research will lead to a better understanding of lithium-ion battery materials and other electroceramics.

A computer simulation shows how columns of atoms in lithium-cobalt oxide should appear. The inset is an actual image taken with a transmission-electron microscope, showing the arrangement of lithium ions among cobalt and oxygen atoms in the lithium-cobalt oxide compound. The oxygen atoms are bright and sharp-edged, the cobalt atoms are fuzzy, and the lithium atoms are small and look a bit stretched.