Monday 29 November 2010

Symmetrical Li-ion Cells based on LiVPO4F

The fabrication and electrochemical properties of novel LiVPO4F//LiVPO4F symmetrical Li-ion cells were described in a paper in ESSL by my group in 2005. A link to the abstract may be found here:

A Symmetrical Lithium-ion Cell based on LiVPO4F

This preliminary work indicated that the fluorophosphate may function successfully as both the positive and negative electrode material in high rate Li-ion cells. At the positive electrode the LiVPO4F uses the V3+/V4+ redox transition while at the negative pole the V3+/V2+ redox couple is operational. Advantageously, the reversible specific capacity for these two reactions is roughly equivalent meaning that the same electrode coating can be used for both electrodes. This simplifies the overall manufacturing process and consequently makes a big difference to the production costs.

Recent work by Okada and co-workers has extended this approach to study the LiVPO4F//LiVPO4F system using an Ionic Liquid electrolyte. This new investigation confirms that the symmetrical cell design demonstrates good rate, safety and cycling performance. The abstract to this work may be found here:

Symmetric Li-ion cell based on LiVPO4F with Ionic Liquid Electrolyte

In summary, the excellent lithium insertion properties of the LiVPO4F active material have again been clearly demonstrated.

Jerry