Battery Chemistry

The image below shows the olivine structure of lithium iron magnesium phosphate LiFeMgPO4 material.

The view is looking along an axis of the crystal structure. The polyhedra aid the eye in seeing the ions grouped as (green) Fe/Mg-enclosing
octahedra and (yellow) phosphate tetrahedra.  The (blue) oxygen ions are made very small to permit viewing of the arrangement of the other ions.

Compare LiFeMgPO4 to other chemistries here.