A series of fluorinated LiCoO2 compounds, LiCoO2−xFx with x = 0.05 − 0.65, were
synthesised by both a sol-gel and a solid-state method. The sol-gel method utilises
LiNO3 and Co(NO3)2.6H2O as Li and Co sources respectively, water and 1-butanol
as solvent for the fluoride precursor LiF, and citric acid as the chelating agent. The
prepared materials were compared using pXRD, SEM, Raman, TG and DTA
analyses. pXRD revealed a secondary phase appearing at x= 0.25 in materials
prepared by the sol-gel method and as early as x= 0.08 in materials prepared by the
thermal solid-state method. Materials prepared by the thermal solid-state method
required higher temperatures and longer times than materials prepared by the solgel
method. The results showed that more fluorine can be incorporated in the
LiCoO2 structure by the sol-gel than the solid-state method. The secondary phase
was identified as lithium oxydifluoride, LiCoOF2. Relatively pure material with
stoichiometry could be prepared by both methods. The space was determined as
either 𝐶������2 or 𝑃������1 and the unit cell dimensions for the two alternatives are reported.
This secondary phase has been reported in the literature, but had not been
positively identified at the time of submission of this dissertation.
Dissertation (MEng)--University of Pretoria, 2018.