Lithium Iron Phosphate-LiFePO4

In LiFePO4, lithium ions diffuse in 1 dimensional channels. It is a relatively economic cathode material, with iron being one of most abundant element on the earth.



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The diffusion channels are 1 dimensional. Lithium ions move by hopping between neighbouring octahedral sites via the imtermediate tetrahedral sites which share faces with the two neighbouring octahedra. The animation shows a lithium ion moves in the channel. In the animation, lithium ion occupies the blue octahedral sites and moves by hopping through the intermediate yellow tetrahedral sites.

It is worth pointing out that though it may look like "channels" in the directions of the other 2 axes, but the energy barrier to diffuse in those directions are much higher, so lithium ions only diffuse in the direction shown in the animation. This is confirmed by Ouyang, 2004.

C. Ouyang, S. Shi, Z. Wang, X. Huang and L. Chen, Phys. Rev. B, 2004, 69, 104303.