Li2FeSiO4 is lead oxide-derived structured and crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with four equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and corners with four equivalent Li(1)O4 trigonal pyramids. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeSi trigonal pyramids. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form corner-sharing OLi2FeSi tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2FeSi tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeSi tetrahedra.
Li2FeSiO4 is lead oxide-derived structured and crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The Li(1)-O(1) bond length is 2.30 Å. The Li(1)-O(2) bond length is 1.99 Å. The Li(1)-O(3) bond length is 1.95 Å. The Li(1)-O(4) bond length is 1.96 Å. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with four equivalent Fe(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. The Li(2)-O(1) bond length is 2.02 Å. The Li(2)-O(2) bond length is 2.07 Å. The Li(2)-O(3) bond length is 1.96 Å. The Li(2)-O(4) bond length is 2.05 Å. Fe(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form FeO4 tetrahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and corners with four equivalent Li(1)O4 trigonal pyramids. The Fe(1)-O(1) bond length is 2.00 Å. The Fe(1)-O(2) bond length is 2.07 Å. The Fe(1)-O(3) bond length is 2.02 Å. The Fe(1)-O(4) bond length is 2.03 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Li(2)O4 tetrahedra, corners with four equivalent Fe(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. The Si(1)-O(1) bond length is 1.66 Å. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeSi trigonal pyramids. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form corner-sharing OLi2FeSi tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of corner and edge-sharing OLi2FeSi tetrahedra. In the fourth O site, O(4) is bonded to one Li(1), one Li(2), one Fe(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OLi2FeSi tetrahedra.