LiNiP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 5-coordinate geometry to one O(3), one O(5), one O(6), and two equivalent O(1) atoms. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, 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 three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. 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 distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(2) atom.
LiNiP2O7 crystallizes in the monoclinic P2_1/c space group. Li(1) is bonded in a 5-coordinate geometry to one O(3), one O(5), one O(6), and two equivalent O(1) atoms. The Li(1)-O(3) bond length is 2.21 Å. The Li(1)-O(5) bond length is 2.08 Å. The Li(1)-O(6) bond length is 2.05 Å. There is one shorter (2.22 Å) and one longer (2.44 Å) Li(1)-O(1) bond length. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Ni(1)-O(1) bond length is 1.97 Å. The Ni(1)-O(2) bond length is 1.88 Å. The Ni(1)-O(3) bond length is 2.10 Å. The Ni(1)-O(5) bond length is 1.90 Å. The Ni(1)-O(6) bond length is 2.28 Å. The Ni(1)-O(7) bond length is 1.87 Å. There are two inequivalent P sites. In the first P site, 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 three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-53°. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.62 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-63°. The P(2)-O(4) bond length is 1.63 Å. The P(2)-O(5) bond length is 1.55 Å. The P(2)-O(6) bond length is 1.52 Å. The P(2)-O(7) bond length is 1.53 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Li(1), one Ni(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(1) atom. 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 distorted bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Li(1), one Ni(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(2) atom.