Chemical delithiation and exfoliation ofLixCoO2

Abstract

Progressive chemical .delithiation of commercially available lithium cobalt oxide (LiCoO2) showed consecutive changes in the crystal properties. Rietveld refinement of high resolution X-ray and neutron diffraction revealed an increased lattice parameter c and a reduced lattice parameter a for chemically delithiated samples. Using electron microscopy we have also followed the changes in the texture of the samples towards what we have found is a critical layer stoichiometry of about LixCoO2 with x=1/3 that causes the grains to exfoliate. The pattern of etches by delithiation suggests that unrelieved strain fields may produce chemical activity.

Cation deficiency associated with the chemical exfoliation of lithium cobalt oxide

“…Using equivalent treatment conditions to Basch and Kim (more detail in Supporting Information), our results were compiled with data from these reports. Our data demonstrate, by incorporating the loss of cobalt (54%), as determined from UV-Vis studies, with the Li:Co ratio determined by ICP-OES, that the total lithium loss is 82%, as opposed to 66% and 74% reported by Basch et al 59 Utilizing reported results of lithium occupancy after acid treatment as determined from neutron diffraction, 37 at.% Li is expected to remain in the structure. 59 .…”

“…Our data demonstrate, by incorporating the loss of cobalt (54%), as determined from UV-Vis studies, with the Li:Co ratio determined by ICP-OES, that the total lithium loss is 82%, as opposed to 66% and 74% reported by Basch et al 59 Utilizing reported results of lithium occupancy after acid treatment as determined from neutron diffraction, 37 at.% Li is expected to remain in the structure. 59 . When comparing to that of previously reported chemical compositions, such as Kim, Basch, and Takahashi this structure varies with the additional consideration of cobalt vacancies and oxygen valence compensation.…”

“…Utilizing reported results of lithium occupancy after acid treatment as determined from neutron diffraction, 37 at.% Li is expected to remain in the structure . Maintaining the Li:Co ratio (0.39) and % Li remaining (18%) as determined from our ICP‐OES data, Li and Co content are linearly approximated to where Li is equal to 37% occupancy; resulting in a chemical formula of [(Li 0.37 [ ] 0.63 )(Co 0.96 [ ] 0.04 )O 2 .…”

“…Specifically, the studies of Kim, Takahashi, and Basch detail a broad range of lithium loss from LCO powders following similar acid treatments (48%‐74%), as determined by X‐ray diffraction (XRD), inductively coupled plasma–atomic/optical emission spectroscopy (ICP‐AES/OES), thermogravimetric‐differential thermal analysis (TG‐DTA), iodometric titration, or X‐ray absorption near edge spectroscopy (XANES). For instance, Basch, Takahashi, and Kim report values of Li 0.37 CoO 2 and Li 0.35 CoO 2 , Li 0.26 H 0.28 CoO 2 respectively, displaying in little agreement between these studies.…”

Investigation of the leaching mechanism of NMC 811 (LiNi0.8Mn0.1Co0.1O2) by hydrochloric acid for recycling lithium ion battery cathodes

“…At the same time, the Li ions could also be replaced by protons via ion-exchange, resulting in M(O,OH) 6 octahedra in the MO 2 layers, like the formation of Ni(O,OH) 6 in the case of acid leaching of LiNiO 2 . 23…”