K2Li2NiO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), and three equivalent O(4) atoms. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. 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 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids,  an edgeedge with one Ni(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. In the second Li site, Li(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Ni(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra, and  an edgeedge with one Li(2)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 two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(2)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 K(1), two equivalent K(2), one Li(1), one Li(2), and one Ni(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), two equivalent K(2), one Li(1), one Li(2), and one Ni(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Li(1), two equivalent Li(2), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(2), three equivalent K(1), one Li(1), and one Ni(1) atom.
K2Li2NiO4 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), and three equivalent O(4) atoms. The K(1)-O(1) bond length is 2.83 Å. The K(1)-O(2) bond length is 2.71 Å. The K(1)-O(3) bond length is 2.80 Å. There are a spread of K(1)-O(4) bond distances ranging from 2.71-2.99 Å. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The K(2)-O(3) bond length is 2.95 Å. The K(2)-O(4) bond length is 3.31 Å. There is one shorter (2.78 Å) and one longer (2.81 Å) K(2)-O(1) bond length. There is one shorter (2.78 Å) and one longer (2.82 Å) K(2)-O(2) bond length. 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 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids,  an edgeedge with one Ni(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. The Li(1)-O(1) bond length is 1.97 Å. The Li(1)-O(2) bond length is 1.98 Å. The Li(1)-O(3) bond length is 2.02 Å. The Li(1)-O(4) bond length is 1.98 Å. In the second Li site, Li(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted LiO4 trigonal pyramids that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Ni(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Ni(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. The Li(2)-O(1) bond length is 2.02 Å. The Li(2)-O(2) bond length is 1.96 Å. There is one shorter (2.02 Å) and one longer (2.06 Å) Li(2)-O(3) 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 two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 trigonal pyramids,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 trigonal pyramid. The Ni(1)-O(1) bond length is 1.83 Å. The Ni(1)-O(2) bond length is 1.80 Å. The Ni(1)-O(3) bond length is 1.83 Å. The Ni(1)-O(4) bond length is 1.79 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), two equivalent K(2), one Li(1), one Li(2), and one Ni(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), two equivalent K(2), one Li(1), one Li(2), and one Ni(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Li(1), two equivalent Li(2), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(2), three equivalent K(1), one Li(1), and one Ni(1) atom.