A article in JACS by Nishimura and co-workers recently caught my eye. The paper describes the promising electrochemical lithium insertion characteristics of the lithium iron diphosphate material, Li2FeP2O7. The link to the paper may be found here:
New Lithium Iron Pyrophosphate as 3.5 V Class Cathode for Lithium Ion Battery
The iron diphosphate demonstrates a reversible specific capacity of around 110 mAh/g at an operating voltage of about 3.5 V vs Li. These are encouraging characteristcs and when combined with the anticipated low cost and good thermal safety, this cathode material may represent an excellent choice for incorporation into large format Li-ion devices. I guess it could even challenge LiFePO4 in some limited applications.
The Li2FeP2O7 material actually represents just one example of a class of lithium metal diphosphates, Li2MP2O7 (where M = Fe, Co, Ni, Mn etc.). The use and preparation of these materials was first recognized in the following issued US patent (Inventors: Barker and Saidi, filed April 2003):
US#7008566: Oligo Phosphate-based Electrode Active Materials
I will wait with great interest to see the developments in this field. Clearly some of the analog materials such as Li2MnP2O7 may offer improved electrochemical behavior over the Fe phase. Will it be possible to extract both lithium ions from the structure?
Jerry
No comments:
Post a Comment