Lithium Perchlorate


Lithium Perchlorate has the highest oxygen content (by weight) of all the Perchlorates. This together with it's density means that it is the salt with the best volume to Oxygen ratio of all the Perchlorates. You can achieve 2.2 times more Oxygen per volume when compared to Ammonium Perchlorate or close to 2 times when making a weight comparison. However since not all combustion products are gas (like Ammonium Perchlorate) only a marginal increase in Isp is realised over Ammonium Perchlorate. It generates a lot of smoke too and is expensive. It is also hygroscopic and forms the trihydrate. It has a well defined melting temperature of 247C and does not show any appreciable decomposition rate until the temperature is raised to over 400C.
The trihydrate is the most common form of the salt and it is extremely difficult to remove the hydrate water. Workers have found that some hydrate remained in a sample held at 300C for 12 hours. The salt will stay in a liquid form if there is any water present as the temperature is raised until the melting point of the anhydrous salt is reached.
Lithium Perchlorate can be made by mixing concentrated solutions of Sodium Perchlorate and Lithium Chloride at elevated temperatures, a crop of NaCl forms and is taken out first and then a crop of lithium Perchlorate separates on cooling. This suits industrial set up's but not one-off batches as the difference in solubilities of the salt and Perchlorate are not far enough apart.
See: Mutual solubility of LiClO4 and NaCl

There is a good description for the manufacture of Lithium Perchlorate in US Patent No. 3,020,124 where high current efficiency's are claimed for the conversion of Lithium Chloride all the way to Perchlorate with Fluoride as a cell additive.
The patent describes the conversion of the Lithium Perchlorate directly into Ammonium Perchlorate by adding Ammonium Carbonate without any processing of the intermediate electrolyte. If you do this you should be warned that the Ammonium Perchlorate so produced may be contaminated with some Ammonium Chlorate. Check your product for Chlorate before conversion.

Lithium Carbonate is available from ceramic supply stores and can be converted to LiCl with HCl. Lithium Chloride has a hydrate (LiCl:H2O).
From experiments conducted by Hashashan it would appear that Li (Per)Chlorate cells are erosive to Lead Dioxide. It also appears that Li is erosive to Tin Oxide Anodes.
SOME USEFUL FORMULA
NameFormulaMolecular Weight
Lithium Chloride (Anhydrous)LiCl42.39
Lithium Chloride (Mono Hydrate)LiCl:H2O60.41
Lithium Perchlorate (Anhydrous) LiClO4106.39
Lithium CarbonateLi2CO373.89

Due to the small radius of the Lithium ion, the salt can be converted into the Perchlorate with ease, when compared to the other Alkali metal salts. See 'The Perchlorates' by Schumacher page 77 (which references: Izgaryshev, N. A. and Khachaturyan, M. G. Doklady Akad. Nauk S. S. S. R., 56 929-32 (1947) & 59, 1125-28, (1948)).

Lithium Perchlorate can be made by electrolysis of the Chlorate at a current density of 200mA per square cm and at a temperature above 20C. SEE: Mochalov, K. N., Trans. Butlerov Inst. Chem. Technol. Kazan, 1 21 - 25, (1934)
Lithium perchlorate can be made by the action of perchloric acid on Lithium Carbonate or Hydroxide . See: Berglund, U ., and Sillen, L. G., Acta Chem. Scand., 2, 116 - 126 (1948)
Lithium Perchlorate can also be made (as most Perchlorates can) by adding the Carbonate or Hydroxide to Ammonium Perchlorate and boiling to drive off the Ammonia. The solution is then boiled away to get the Li Perchlorate
See Transactions of the American Electrochemical Society., 29, 323 (1916) Bennett, C. W., and Mack, E. L. for another source of info.

See here for an interesting propellant using Lithium Perchlorate
See also Patent No. GB 1047474 for a polymer of Li Perchlorate.

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