Positive Electrode In Lithium Batteries Research Articles

The cycling properties of the Li xNi 1− yCo yO 2 electrode

The LiNiO 2LiCoO 2 system exhibits a complete solid solution. These materials crystallize in the rhombohedral system with a layered structure. They have been used as positive electrode in lithium batteries. Up to 0.5 lithium atom can be reversibly deintercalated in the 3.5 to 4.0 V potential range. The highest specific energy (close to 500 W h/kg) is obtained in the Li x Ni 0.7Co 0.3O 2 system. Moreover, the very small volume change upon deintercalation increased their interest for application point of view.

Electrochemical and physical properties of the Li xNi 1− yCo yO 2 phases

A crystal chemistry study of the LiNi 1− y Co y O 2 system has been realized. These materials exhibit a layered structure (R 3 m-O3 type) for 0≤ y≤1. They have been used as positive electrode in lithium batteries. Up to 0.6 lithium atom can be reversibly deintercalated for cell voltages lying in the 3.5–4 V range. For 0≤ y≤0.5, the shape of all the charge curves is very similar with a small decrease in potential when y increases due to the influence of cobalt which, however, does not participate significantly in the redox process. For materials with a larger cobalt amount ( y≥0.6) the nickel ions are first oxidized to the tetravalent state, before the cobalt ions. This behavior is confirmed by the evolution of the electronic properties versus the lithium amount.

Utilization of V 6O 13 as the positive electrode in lithium batteries

V 6O 13 has been utilized as the active material of the positive electrode in lithium batteries. Such batteries, using 1 M LiClO 4 in propylene carbonate as electrolyte, have been built and tested galvano-statically, the lithium electrode being periodically replaced when consumed by its reaction with the organic electrolyte during the charges. The nature and content of the carbon added as current collector have been optimized, leading to 5 wt.% of Ketjen black in the positive electrode. The contact between the V 6O 13 grains and the electrolyte has been improved, leading to a substaintial increase in the initial capacity. However, a decrease in capacity is observed whatever the electrode technology during the first 200 cycles. Afterwards, a steady state seems to be reached.

Electrochemical behavior of Fe xNb 1−xSe 3 (x=0 ≈ 0.25) with one-dimensional structure as new positive electrodes for secondary lithium batteries

Electrochemical behavior of Fe xNb 1−xSe 3 (x=0 ≈ 0.25) as positive electrodes for lithium batteries were investigated in various lM LiClO 4 electrolytic solutions of propylene carbonate, butyrolactone, dimethyl sulfoxide and sulfolane. Fe 0.25Nb 0.75Se 3 electrode shows good reversibility and the practical energy density is about 300 Wh/Kg-selenide. The discharge potentials of NbSe 3 and Fe 0.25Nb 0.75Se 3, both having one-dimensional structure, strongly depend on the kind of solvent in the electrolyte, due to the insertion of a solvated Li +ion into the inner layer of the selenide. In addition, on the discharge of a series of NbSe x (x=1.7, 2, 3, 4 and 4.5), the number of electron transferred during discharge is found to correspond to the value of x but 1.7.

Generateurs electrochimiques lithium/composes d'insertion du graphite avec FeCl 3, CuCl 3, MnCl 2 et CoCl 2

First stage graphite intercalation compounds with FeCl 3, CuCl 2, MnCl 2, and CoCl 2 have been synthesized and used as positive electrodes in lithium batteries. Electrochemical discharge techniques have enabled the energy densities and the current and energy efficiencies to be calculated. The results have wide practical applications.