Use of vanadium oxide and/or aluminum bronzes as a cathode mater

Details Use of vanadium oxide and/or aluminum bronzes as a cathode mater Use of vanadium oxide and/or aluminum bronzes as a cathode mater

1994-07-05

1995-09-26

Kalafut, Stephen

Chemistry: electrical current producing apparatus, product, and

Current producing cell, elements, subcombinations and...

Electrode

429221, 429194, H01M 452, H01M 448

Patent

active

054533376

DESCRIPTION:

BRIEF SUMMARY
This is application is a national phase of a application PCT/FR92/01167 with publication number WO 93/12550.
The present invention relates to the use of vanadium oxide bronzes as a cathode material in electrochemical generators.
It more particularly applies to secondary electrochemical generators, whose operation is based on the intercalation of a metal ion, such as lithium in the cathode material.
For close to twenty years, the use of primary, lithium electrochemical generators has provided energy sources with better performance characteristics than conventional batteries with respect to the energy density, the life and the operation in a wide temperature range. Such primary generators are particularly used for the supply of equipment requiring low current densities, such as watches, calculators and for maintaining memories.
In view of the good performance characteristics of these primary lithium generators, much research has been carried out with a view to producing secondary lithium generators having the characteristics inherent in lithium anode batteries and the longer life of accumulators. The development of such generators involves the reversibility of the reactions at both the anode and the cathode.
In addition, much research has been devoted to investigating cathode materials able to reversibly insert metal ions such as lithium ions. Among these considerable research has been directed at those based on vanadium pentoxide V.sub.2 O.sub.5, which have high performance characteristics as a result of the standard, very high potential of V.sup.5+ and the compatibility of the oxidation potential of these materials with the stability range of the organic electrolytes conventionally used in electrochemical generators. Moreover, V.sub.2 O.sub.5 has a structure intermediate between the tunnel structure of rutile-type oxides and that of MoO.sub.3 -type oxide laminas.
The operating characteristics of a secondary electrochemical generator using V.sub.2 O.sub.5 as the electrode material will largely depend on the reversibility of the insertion reaction of a metal such as lithium (Li.sup.+) in the host lattice of the V.sub.2 O.sub.5, in accordance with the following reaction diagram: preferably for a high voltage, with a maximum faradic capacitance, i.e. a maximum lithium x insertion level over a large number of galvanostatic cycles.
With regards to the V.sub.2 O.sub.5 cycling behaviour, it is known that the constant current reduction of V.sub.2 O.sub.5 in a conventional electrolytic medium takes place in four separate stages as described by Kumagai et al in Electrochimica Acta, 28, 1983, pp 17-22.
FIG. 1 illustrates the typical V.sub.2 O.sub.5 discharge curve in propylene carbonate containing 1 mole/l of LiClO.sub.4 at 20.degree. C. using V.sub.2 O.sub.5 at the cathode and a lithium anode.
FIG. 1, which represents the evolution of the potential as a function of the exchanged lithium quantity, shows that the first two stages of said reduction, which are characterized by a potential above 3 V and a Li.sub.y V.sub.2 O.sub.5 composition range with 0.ltoreq.y.ltoreq.1, corresponding to the conventional cycling of Li/V.sub.2 O.sub.5 generators for which a perfect reversibility is observed. The third range corresponds to a partial reversibility loss, whose mechanism has not been completely explained, and a complete irreversibility is observed after a deep discharge involving more than 2.4 lithium ions.
Much research has also been carried out with a view to improving the cyclability of materials similar to V.sub.2 O.sub.5 in order to bring about a greater reduction involving the third and fourth insertion stages located at 2.2 and 1.8 V. Electrode materials with a greater reduction are described e.g. by Cocciantelli et al in Journal of Power Sources, 34, 1991, pp 103-111 and in FR-A-2 655 777, as well as by Delmas et al in Journal of Power Sources, 34, 1991, pp 113-188 and WO 90/11623.
Thus, in said two documents the mass capacitance of an electrochemical generator has been increased by increasing the lithium insertion l

REFERENCES:
patent: 4668594 (1987-05-01), Yamaura et al.
patent: 4874680 (1989-10-01), Koshiba et al.
patent: 5175068 (1992-12-01), Ryan
patent: 5298349 (1994-05-01), Tekeuchi

Affiliated with

Also associated with

Rating

Use of vanadium oxide and/or aluminum bronzes as a cathode mater does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Use of vanadium oxide and/or aluminum bronzes as a cathode mater, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of vanadium oxide and/or aluminum bronzes as a cathode mater will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1551363