LiNiPO4 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  an edgeedge with one Li(1)O4 trigonal pyramid. Ni(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with four equivalent Ni(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 in a 3-coordinate geometry to one Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded to two equivalent Li(1), one Ni(1), and one P(1) atom to form edge-sharing OLi2NiP trigonal pyramids. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Ni(1) and one P(1) atom.
LiNiPO4 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra,  an edgeedge with one P(1)O4 tetrahedra, and  an edgeedge with one Li(1)O4 trigonal pyramid. The Li(1)-O(1) bond length is 1.96 Å. The Li(1)-O(3) bond length is 2.02 Å. There is one shorter (1.99 Å) and one longer (2.26 Å) Li(1)-O(2) bond length. Ni(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form NiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. The Ni(1)-O(1) bond length is 2.00 Å. The Ni(1)-O(2) bond length is 2.02 Å. The Ni(1)-O(3) bond length is 1.95 Å. The Ni(1)-O(4) bond length is 1.92 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with four equivalent Ni(1)O4 tetrahedra, corners with two equivalent Li(1)O4 trigonal pyramids, and  an edgeedge with one Li(1)O4 trigonal pyramid. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.58 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.52 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded to two equivalent Li(1), one Ni(1), and one P(1) atom to form edge-sharing OLi2NiP trigonal pyramids. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one Ni(1) and one P(1) atom.