Kenneth Rosina
From Grey Lab Page
As anybody who owns a laptop or cell phone knows, rechargeable batteries that have been regularly used don't last as long from a single charge as new ones. This is an annoyance to us, but can devestate electric auto makers. Popular current materials, like LiCoO2, are reported to lose at much as 57% of its original capacity over 30 cycles (Appapillai et al.).
This is thought to be due to, among other things, impedance growth through microcracks in the cathode material and dissolution of some transition metal from the layered cathode structure into the electrolye. Various coating compositions and techniques are being applied to Li[Li1/9Ni1/3Mn5/9]O2 to reduce capacity loss. AlPO4 and AlF3 coatings are being investigated through reversible cycling, powder X-ray diffraction, and various NMR techniques. A properly developed coating material will provide a strong, yet conductive barrier between the cathode and electrolyte that can hold transition metal atoms in the layered structure, prevent fractures in the cathode, and facilitate Li+ ion transport in and out of the layered cathode structure.
Reference
Appapillai et al. Chem. Mater. 2007, 19, 5748-5757.
