Chemistry: electrical and wave energy – Processes and products
Patent
1985-01-07
1986-12-16
Niebling, John F.
Chemistry: electrical and wave energy
Processes and products
528422, 429212, 429213, C25C 100, H01M 460
Patent
active
046295402
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of polyanilines more particularly used as the active electrode material of an electrochemical generator.
In the invention, the term polyanilines is understood to mean polymers resulting from the condensation of aniline, as well as that of derivatives thereof.
It is known that polyanilines are used for producing electrochemical batteries (cf e.g. French Pat. No. 1,519,729), but their preparations have poor efficiency levels and lead to compounds containing numerous poorly defined oligomers. This leads to a dispersion of the electrochemical properties and consequently a dispersion of the qualities of the batteries produced therefrom.
Thus, the present invention proposes a process for the preparation of polyanilines having efficiency levels close to the theoretical levels, whilst no secondary oligomer products are formed, which can be used as the active electrode material in a battery.
More specifically, the present invention relates to a process for the preparation of polyanilines, characterized in that a compound chosen from among aniline, para-aminodiphenylamine and derivatives thereof is oxidized in a super acid in the liquid phase containing fluoride ions.
Super acid is understood to mean all acid mixtures, whose equivalent pH is below 0 with reference to water, such as e.g. sulphuric acid, phosphoric acid, hydrofluoric acid, benzene sulphonic acid, etc.
According to a secondary feature of the invention, the concentration of the liquid phase in the compound chosen from among aniline, para-aminodiphenylamine and their derivatives is between 10.sup.-3 and 4 mol/l.
According to another secondary feature of the invention, the liquid phase containing the super acid and the fluoride ions is constituted by the eutectic NH.sub.3, HF, which contains approximately 54.2% of free HF and 80.9% of total HF (by weight).
It is also possible to use RNH.sub.2, HF mixtures with R representing an alkyl radical and pyridine, HF mixtures.
According to another secondary feature of the invention, the fluoride ion concentration of the liquid phase is 0.5 to 10 ions.g/l. The liquid phase can be an aqueous or organic solution containing the super acid and the fluoride ions.
By mixing the aniline or its derivatives and the super acid containing the fluoride ions, an anilinium fluoride is obtained, whose concentration can vary between 10.sup.-3 and 4 mol/l.
The preparation procedures for the polyanilines are as follows: thereof and the super acid solution are mixed; electrochemically.
The chemical route involves mixing the preceding solution with a solution in the same super acid of oxidizing agents, such as potassium dichromate, potassium permanganate, osmium tetroxide and ammonium persulphate.
When oxidation takes place chemically, the concentration of aniline, a para-aminodiphenylamine or a derivative of aniline or para-aminodiphenylamine of the super acid solution is such that in the final liquid phase, there is a concentration of 10.sup.-3 to 4 mol/l of aniline, para-aminodiphenylamine or one of their derivatives. In the same way, the concentration of the oxidizing agent in the solution added to the solution of aniline, para-aminodiphenylamine or one of their derivatives is such that in the final liquid phase an oxidizing agent concentration of 10.sup.-3 to 4 mol/l is obtained.
When using the electrochemical route, the polyanilines are electrolytically deposited on a support, such as of platinum, nickel, Monel, carbon or any other carbon-coated support, e.g. a stainless steel support coated with graphite paint. The current densities used for this deposition vary between 0.05 and 100 mA/cm.sup.2, polyaniline formation being quantitative. In this way, the electrode of the battery is directly obtained. The polyanilines prepared according to this second procedure are very stable and adhere very strongly to the support (grid or plate).
The polyanilines prepared according to the process of the invention have much better electrochemical properties than other conductive con
REFERENCES:
patent: 4488943 (1984-12-01), Skotheim
Volkov et al, J. Electroanal. Chem., 115 (1980), pp. 279-291.
Diaz et al, J. Electroanal. Chem., 111 (1980), pp. 111-114.
Ruby, Daniel, "New Promise for the Electric Car: Plastic-Metal Batteries", Popular Science, Feb. 1982, pp. 89-92.
Advanced Battery Technology, vol. 17, No. 11, Nov. 1981, pp. 1-8.
Geniees Eugene
Pierre Gerard
Santier Christian
Tsintavis Constantin
Commissariat a l''Energie Atomique
Niebling John F.
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