Structural Features of Low-Temperature LiCoO2and Acid-Delithiated Products

The Science of Electrode Materials for Lithium Batteries

“…In LiCoO 2 subjected to hundreds of chargedischarge cycles, especially at temperatures of 70°C or so, we found some cubic spinel phase in the material by TEM study. This cubic spinel phase is well-known to be present in fresh LiCoO 2 processed at lower temperatures [16,26], and had been reported previously in battery electrode material [21,22]. In our recent work, we identified cubic spinel phase formation on the surface of LiCoO 2 particles that had the O3 structure before cycling.…”

“…In work on LiCoO 2 by transmission electron microscopy (TEM), we studied dislocations in the O3 structure, which had been observed previously [21,22]. By performing systematic tilting of the sample to orient the dislocations into null contrast conditions, we identified the Burger's vector of the perfect dislocations.…”

In-Situ Neutron Studies of Electrodes for Li-Ion Batteries Using a Deuterated Electrolyte: LiCoO2as a Case Study

“…Previous in-situ studies of LiCoO2 using commercial batteries by Sharma et al [45] showed that both forms of LiCoO2; the hexagonal one and the spinel-like phase [46][47][48][49][50][51][52], undergo a series of phase transitions during cycling, and it was proposed that the gradual build-up of the spinel-type phase might be a contributing factor to the observed capacity fade within LixCoO2 based batteries. Rodriguez et al [53] determined the variations in the lattice parameters of a LiCoO2-type material as a function of charge state, also in a commercial Liion cell, whilst changes in both the lattice parameters and lithium occupancies with repeated cell cycling were shown to be correlated with the degradation of cell performance [54].…”

Towards Hydrogen Energy: Progress on Catalysts for Water Splitting

“…2; top), and are used as battery materials due to the high mobility of lithium. [16,17] The spinel polymorph contains Co 4 O 4 cube subunits and forms above 3508C as the exclusive phase at this temperature. However, at temperatures greater than 5008C and longer calcination times, it transforms to the thermodynamically favoured layered polymorph.…”

“…[20] The higher calcination temperature and longer reaction times used to form the layered polymorph gives rise to increasing crystallite size. [16] To reduce this difference in particle sizes, the authors adapted a sol-gel method [21] that forms nano-particles (50-100 nm) and limited particle size differences to only two-fold. Powder X-ray diffraction (PXRD) confirmed the crystal structure transformation between 400 (all cubic), 500, 600, and 7008C (all layered), while the rate of oxygen evolution decreased to zero for this range, even when accounting for the surface area.…”