Influence of the Initial Li/Co Ratio in LiCoO₂ on the High-Voltage Phase-Transitions Mechanisms

Abstract

The influence of the initial Li/Co stoichiometry in LiCoO (LCO) (1.00 ≤ Li/Co ≤ 1.05) on the phase-transition mechanisms occurring at high voltage during lithium deintercalation ( V > 4.5 vs Li/Li) was investigated by in situ X-ray diffraction. Even if the excess Li in LiCoO does not hinder the formation of the H1-3 and O1 phases, the latter are obtained at higher voltages and exhibit larger c parameters compared with their analogues formed from LiCoO. We also showed that for the stoichiometric LiCoO the deintercalation process is more complex than already reported, with the formation of an intermediate structure between H1-3 and O1.

An Overview on the Advances of LiCoO2 Cathodes for Lithium‐Ion Batteries

“…Moreover, Carlier et al found that the initial Li/Co stoichiometry in LiCoO 2 (1.00 ≤ Li/Co ≤ 1.05) influences the phase‐transition process at high voltage (>4.5 V). [ 33 ] The deintercalation process of Li 1.00 CoO 2 is more complex and a new intermediate phase is detected between H1‐3 and O1. Yan et al conducted systematic investigations on the failure mechanisms of LiCoO 2 over 4.7 V and suggested that the capacity loss is mainly due to bulk structure degradation.…”

Scrutiny of the LiCoO2 Composite Electrode/Electrolyte Interface by Advanced Electrogravimetry and Implications for Aqueous Li-Ion Batteries

“…[1][2][3][4] The postulated benefits of Aqu-LIBs have stimulated the pursuit for new electrode materials, compatible with narrow electrochemical stability window of aqueous electrolytes. 5 The most widely studied electrode materials in organic LIBs (LiCoO2 (LCO) [6][7][8][9] and LiFePO4 (LFP) [10][11] etc.) have also been revisited for their potential use in the aqueous analogues.…”

The Layered Oxides in Lithium and Sodium‐Ion Batteries: A Solid‐State Chemistry Approach

“…A typical cycling curve of a lithium//Li x CoO 2 cell is shown in Figure 5 . [ 68 ] The deintercalation/intercalation is reversible. The small irreversibility observed after the first discharge depends on the cell cycling conditions and also of the exact stoichiometry of the material.…”

“…The biphasic domain due to the insulator/metal transition observed for the stoichiometric phase is replaced by a continuous variation for the overlithiated phase. [ 68 ] In the overlithiated material for x = 0.5, the presence of structural defects in the CoO 2 slabs prevents from the Li/vacancy ordering. In Figure 7 , the structural model of the defect is represented.…”

“…Another difference between lithium and sodium system is the variation on the voltage versus the composition. For the Li//O3‐LiCoO 2 battery [ 68 ] the voltage increases from 4 V ( x = 0.95) to 4.3 V ( x = 0.30) while for Na//O3‐NaCoO 2 one it increases ( Figure 22 ) from 2.6 V ( x = 0.95) to 4.0 V ( x = 0.30) This difference in voltage variations, [ 149 ] independent of the negative electrode, results from the difference of energy of the starting materials. It is easier to deintercalate electrochemically sodium than lithium.…”