Materials Data on Na(CoO2)2 by Materials Project

NaCo2O4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.54 Å. There are two inequivalent Co+3.50+ sites. In the first Co+3.50+ site, Co+3.50+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.78–2.20 Å. In the second Co+3.50+ site, Co+3.50+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There are a spread of Co–O bond distances ranging from 1.94–2.09 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+ and three Co+3.50+ atoms. In the second O2- site, O2- is bonded to two equivalent Na1+ and three Co+3.50+ atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 square pyramids. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+ and three Co+3.50+ atoms. In the fourth O2- site, O2- is bonded to two equivalent Na1+ and three Co+3.50+ atoms to form a mixture of distorted corner and edge-sharing ONa2Co3 trigonal bipyramids.

NaCo₂O₄结晶于三斜晶系P1空间群（triclinic P1 space group），其晶体结构为三维无限骨架。Na1+采取六配位几何构型，与6个O2-原子成键，Na–O键长分布范围为2.38~2.54 Å。该晶体存在两种不等价的Co+3.50+晶位：在第一种Co+3.50+晶位中，Co+3.50+与6个O2-原子成键，形成共边共享的CoO₆八面体（edge-sharing CoO6 octahedra），Co–O键长分布范围为1.78~2.20 Å；在第二种Co+3.50+晶位中，Co+3.50+同样与6个O2-原子成键，形成共边共享的CoO₆八面体，Co–O键长分布范围为1.94~2.09 Å。此外，晶体存在四种不等价的O2-晶位：在第一种O2-晶位中，O2-以畸变矩形跷跷板型几何构型与1个Na1+和3个Co+3.50+原子成键；在第二种O2-晶位中，O2-与2个等价的Na1+和3个Co+3.50+原子成键，形成兼具畸变角共享与边共享的ONa₂Co₃四方锥结构单元；在第三种O2-晶位中，O2-以畸变矩形跷跷板型几何构型与1个Na1+和3个Co+3.50+原子成键；在第四种O2-晶位中，O2-与2个等价的Na1+和3个Co+3.50+原子成键，形成兼具畸变角共享与边共享的ONa₂Co₃三角双锥结构单元。