Lithium cobalt(II) pyrophosphate, Li_1.86CoP₂O₇, from synchrotron X-ray powder data

Abstract

Key indicators: powder synchrotron study; T = 297 K; mean (O-Li) = 0.020 Å; disorder in main residue; R factor = 0.057; wR factor = 0.080; data-to-parameter ratio = 91.1.Structure refinement of high-resolution X-ray powder diffraction data of the title compound gave the composition Li 1.865 CoP 2 O 7 , which is also verified by the ICP measurement. Two Co sites exist in the structure: one is a CoO 5 square pyramid and the other is a CoO 6 octahedron. They share edges and are further interconnected through P 2 O 7 groups, forming a three-dimensional framework, which exhibits different kinds of intersecting tunnels containing Li cations and could be of great interest in Li ion battery chemistry. The structure also exhibits cation disorder with 13.5% Co residing at the lithium (Li1) site. Co seems to have an average oxidation state of 2.135, as obtained from the strutural stochiometry that closely supports the magnetic susceptibility findings. (1998). Pseudovoigt profile coefficients as parameterized in Thompson et al. (1987) and Finger et al. (1994). Related literature ExperimentalCrystal data

Structural and Electronic Changes in Li2FeP2O7 during Electrochemical Cycling

“…Consequently, the remaining 1/3 of the fivecoordinated iron occupies a LiO 5 site. This is a feature of Li 2 MP 2 O 7 for M = Fe 1 and Co 15,16 and also for Mg-17 and Nidoped 18 Li 2 FeP 2 O 7 , but not for M = Mn, 19 where no Li−Mn mixing occurs.…”

First-Principles Characterization of Lithium Cobalt Pyrophosphate as a Cathode Material for Solid-State Li-Ion Batteries

“…While the P 2 O 7 structural framework is nearly the same in these two crystal structures, there are subtle differences in the lithium contents and vacancy defects. The crystal structure in ref shows five types of lithium, while only four types are detected in ref . Moreover, the structure in ref exhibits more vacancy defects.…”

“…The crystal structure of LCPO has been reported in two different studies: one by Kim et al using neutron and X-ray diffraction (ND and XRD) and another by Zhou et al using synchrotron X-ray powder data . The unit formulas (space group) are found to be Li 1.855 CoP 2 O 7 ( P 2 1 / c ) and Li 1.86 CoP 2 O 7 ( P 2 1 / a ).…”

“…The crystal structure of LCPO has been reported in two different studies: one by Kim et al using neutron and X-ray diffraction (ND and XRD) 21 and another by Zhou et al using synchrotron X-ray powder data. 22 The unit formulas (space group) are found to be Li In the literature, there are only a few theoretical studies concerning the effects of defects and lithium diffusion in lithium transition-metal pyrophosphates; 23−25 it is especially rare to study LCPO. Nevertheless, Lee and Park studied the structure, defect chemistry and lithium transport in Li 2 MP 2 O 7 (M = Fe, Mn, and Co) using forcefield-based simulations with empirical potential parameters.…”

Multiscale factors in designing alkali-ion (Li, Na, and K) transition metal inorganic compounds for next-generation rechargeable batteries

“…11 Schematic illustration of phosphates, sulfates, silicates, borates and Prussian blue analogues crystal structures. [133][134][135][136][137][138][139][140]…”