Li4CO4 crystallizes in the monoclinic Cm space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted corner-sharing LiO4 tetrahedra. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. In the third Li site, Li(3) is bonded in a distorted trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. C(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Li(3), two equivalent Li(2), and one C(1) atom. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Li(3) atoms to form OLi6 octahedra that share corners with eight equivalent O(3)Li3C trigonal pyramids and edges with two equivalent O(2)Li6 octahedra. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted OLi3C trigonal pyramids that share corners with four equivalent O(2)Li6 octahedra, corners with two equivalent O(3)Li3C trigonal pyramids, and  an edgeedge with one O(3)Li3C trigonal pyramid. The corner-sharing octahedral tilt angles range from 56-64°.
Li4CO4 crystallizes in the monoclinic Cm space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form distorted corner-sharing LiO4 tetrahedra. There is one shorter (1.97 Å) and one longer (1.99 Å) Li(1)-O(2) bond length. Both Li(1)-O(3) bond lengths are 2.08 Å. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(3) atoms. The Li(2)-O(1) bond length is 2.30 Å. The Li(2)-O(2) bond length is 1.87 Å. There is one shorter (1.97 Å) and one longer (2.01 Å) Li(2)-O(3) bond length. In the third Li site, Li(3) is bonded in a distorted trigonal non-coplanar geometry to one O(1) and two equivalent O(2) atoms. The Li(3)-O(1) bond length is 1.95 Å. There is one shorter (1.97 Å) and one longer (2.01 Å) Li(3)-O(2) bond length. C(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(3) atoms. The C(1)-O(1) bond length is 1.29 Å. Both C(1)-O(3) bond lengths are 1.31 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Li(3), two equivalent Li(2), and one C(1) atom. In the second O site, O(2) is bonded to two equivalent Li(1), two equivalent Li(2), and two equivalent Li(3) atoms to form OLi6 octahedra that share corners with eight equivalent O(3)Li3C trigonal pyramids and edges with two equivalent O(2)Li6 octahedra. In the third O site, O(3) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted OLi3C trigonal pyramids that share corners with four equivalent O(2)Li6 octahedra, corners with two equivalent O(3)Li3C trigonal pyramids, and  an edgeedge with one O(3)Li3C trigonal pyramid. The corner-sharing octahedral tilt angles range from 56-64°.