Layered LiCoO

Figure 17.14 SEM images for the morphology of (a) the renovated LiCoO phase and (b) the pristine layered LiCoO reference powder.

The contribution of electric field to lithium transport has been considered by a few authors. Pyun et al argued on the basis of the Armand s model for the intercalation electrode that lithium deintercalation from the LiCoO composite electrode was retarded by the electric field due to the formation of an electron-depleted space charge layer beneath the electrode/electrolyte interface. Nichina et al. estimated the chemical diffusivity of lithium in the LiCo02 film electrode from the current-time relation derived from the Nemst-Planck equation for combined lithium migration and diffusion within the electrode. 

Fig. 10.7 XPS spectra of the Al 2p binding energies from the AI2O3 dashed line) and AlPO solid line) nanoscale-coating layer on LiCoO ...

Fig. 10.13. In this case, the eell eontaining the Al203-coated LiCoO cathode exhibits the maximum surfaee temperature of 500°C. However, AlPO -coated LiCoO shows a maximum temperature of only 60°C, indieating that the AlPO -coating layer is still stable after the suecessive short cireuits in eontrast to the Al O -coating layer.

A typical Li-Ion cell consists of a positive electrode composed of a thin layer of powdered metal oxide (e.g., LiCoO ) mounted on aluminum foil and a negative electrode formed from a thin layer of powdered graphite, or certain other carbons, mounted on a copper foil. The two electrodes are separated by a porous plastic film soaked typically in LiPF dissolved in a mixture of organic solvents such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), or diethyl carbonate (DEC). In the charge/discharge process, lithium ions are inserted or extracted from interstitial space between atomic layers within the active materials. 

LiVOj is isostructural with LiCoO it has a da ratio of 5.20 (space group R3m ) [74]. Unlike LiCoO, and LiNiOj, LiVOj is unstable to delithiation at x 0.3 inLi,, .V02, the vanadium ions become mobile and diffuse from the octahedral sites (3b) of the vanadium layer into octahedral sites (3a) left vacant by the extracted lithium ions. The diffusion of vanadium ions takes place through face-shared tetrahedra linking the octahedra of alternate layers and is believed to occur by a disproportionation reaction in which ions occupy tetrahedral (6c) sites [74, 751 ... 

Co-substituted LiNiO (resulting in LiNij Cop ) has the advantage of combining the favourable properties of LiNiO and LiCoOj and yet also have a higher structural stability than the pure Ni-oxide and a potentially lower cost than LiCoO. Its crystal structure (Fig. 9) is of the a-NaFeOj-type (space-group R3m), which is a layered, rhombohedral structure in which the lithium... 

A layered oxide, such as lithium cobalt oxide (LiCoO)... 

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