We present a first-principles electronic band structure for pure

{LiFePO}_{4},

delithiated

{FePO}_{4},

and Cr-doped

{LiFePO}_{4} .

It indicates that not only Fe but also O atoms are oxidized in the delithiation process, while P is little affected. This is in contrast to the usual view of the intercalation reaction that the removal of Li only transforms Fe from

{Fe}^{2 +}

{Fe}^{3 +},

but in agreement with the present x-ray photoemission spectroscopy experiment. Calculation also assumes a significant enhancement of electronic conductivity when lithium ions are replaced by cations with higher valence,

{Cr}^{3 +} .

We also confirm experimentally, for

{Li}_{1 - 3 x} {Cr}_{x} {FePO}_{4}

with

x = 0.01

and 0.03, an enhancement of the electronic conductivity up to eight orders of magnitude comparing with pure

{LiFePO}_{4} .

Besides the conventional p-type doping conductivity, another mechanism has been suggested, which involves the electron hopping within a cluster surrounding the doping atom and related vacancies, and electron tunneling between these conducting clusters.

Publications with shared reference:

0 publications found