Real-Time Crystallization of LiCoO₂from β-Co(OH)₂and Co₃O₄: Synthetic Pathways and Structural Evolution

Abstract

Cobalt oxides are technologically important materials, especially when lithiated for application as Li-ion cathodes. However, several phases may crystallize during solid-state synthesis in the Li−Co−O−H system. The solid-state reactions of LiOH• H 2 O with both β-Co(OH) 2 and Co 3 O 4 have been investigated here through the combined use of high-resolution in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy, with a special focus on the low-temperature range (RT−600 °C). We show that several spinel phases (AB 2 O 4 and A 2 B 2 O 4 with A, B = Li, Co) are formed in the range 300−525 °C, whose unambiguous identification is only possible through the complementary use of Raman spectroscopy as their XRD patterns are almost identical. While the various structures evidenced are mostly stabilized over similar temperature ranges regardless of the initial choice of Co precursor, the lithiated spinel phases are observed at lower temperatures for samples synthesized from Co(OH) 2 . Moreover, their respective Li and Co fractions and crystallinity are strongly affected by the initial choice of precursor. These findings have strong implications in the preparation and optimization of both Co-based cathode active materials and Co-based coatings for other cathode active materials.

In situ neutron diffraction to investigate the solid-state synthesis of Ni-rich cathode materials

“…As is commonly reported in the literature, the presence of Mn in the structure necessitates higher annealing temperatures to form a pure layered phase (Liu et al, 2022;McCalla & Dahn, 2013). Previous studies have also shown that the reaction pathway and observed intermediate phases differ markedly for various cathode-material compositions despite targeting the same final layered structure (Ying et al, 2023;Duffiet et al, 2022;Hua et al, 2019). Qualitatively, the in situ diffraction data collected from the Mn-containing mixtures look very similar to the LNO data shown earlier in Fig.…”

Interplay Between Element-Specific Distortions and Electrocatalytic Oxygen Evolution for Cobalt-Iron Hydroxides

“…[41][42][43][44][45][46][47] A recent report analyzing the transformation of b-Co(OH) 2 to LiCoO 2 contains well-defined spectra for b-Co(OH) 2 , CoOOH and Co 3 O 4 with associated XRD. 48 The report shows (i) Raman vibrations at 250 (weak), 431 (moderate), and 503 (strong) cm -1 for b-Co(OH) 2 , (ii) a broad feature between ca. 400 and 640 cm -1 and peaks at 505 (moderate), 597 (moderate), and 640 (weak) cm -1 for CoOOH, and (iii) peaks at 196 (strong), 493 (strong), 532 (weak), 616, weak) and 697 (moderate) cm -1 for Co 3 O 4 .…”

Interplay Between Element-Specific Distortions and Electrocatalytic Oxygen Evolution for Cobalt-Iron Hydroxides

“…[42][43][44][45][46][47][48] A recent report analyzing the transformation of -Co(OH)2 to LiCoO2 contains well-defined spectra for -Co(OH)2, CoOOH and Co3O4 with associated XRD. 49 The report shows (i) Raman vibrations at 250 (weak), 431 (moderate), and 503 (strong) cm -1 for -Co(OH)2, (ii) a broad feature between ca. 400 and 640 cm -1 and peaks at 505 (moderate), 597 (moderate), and 640 (weak) cm -1 for CoOOH, and (iii) peaks at 196 (strong), 493 (strong), 532 (weak), 616, weak) and 697 (moderate) cm -1 for Co3O4.…”