IL40132A - Electric batteries - Google Patents

Claims (7)

1. An electric "battery including a plurality of cells arranged in series, each cell comprising: a "bipolar electrode which serves to separate neighbouring cells; an aqueous electrolyte of zinc bromide vhich is continuously circulated through the cells during the charging and discharging processes, and stored in an autonomous tank when the battery is not in use; the bipolar electrode having deposited on one side a zinc anode and on the other side a bromine cathode including an active cathodic mass, the active cathodic mass containing an active cathodic substance which is substantially insoluble in water and which is capable of combining with cathodic bromine to form solid addition products¾ the active cathodic substance being selected from at least one of the group comprising alkylammonium perchlorates, diamine bromides, diamine perchlorates, triamine bromides and triamine perchlorates, additive substances being dissolved in the electrolyte to reduce the solubility of the active cathodic substance, to increase the conductivity and the acidity of the electrolyte and to encourage the zinc to deposit in a thin and uniform layer.

2. A battery as claimed in claim 1 in which the active cathodic substance includes tetramethylammonium perchlorate and/or tetrabutyl-ammonium perchlorate and/or tetraethylammonium perchlorate. J. A battery as claimed in claim 1 in which the active cathodic substance includes methonium bromide and/or methonium perchlorate. 4« A battery as claimed in claim 3 in which the active cathodic substance includes pentamethonium bromide and/or pentaethonium perchlorate and/or hexamethonium bromide and/or hexaraethonium perchlorate and/or decamethonium bromide and/or decamethonium perchlorate. 5. A battery as claimed in claim 1 in which the active cathodic substance includes phenyltrijaethylammonium bromide and/or phenylrimethyl-ammonium perchlorate and/or cetyltrimethylammonium bromide and/or cetyltrimethylammonium perchlorate. . . 6. Λ battery as claimed in claim 1 in v/hich the active cathodic substance comprises tetramethylamonium perchlorate and he.iamethonium bromide. 7· Λ battery as claimed in air/ preceding claim in which, each bipolar electrode comprises an impermeable conducting membrane on one side of which is deposited the zinc anode and on the other side of which is a layer of porous felt impregnated with the active cathodic substance, the impregnated porous felt constituting the bromine cathode.

3. A battery as claimed in claim 7 in v/hich the layer of porous felt is impregnated wit a salt which is soluble in water and which, by reacting with an exchange salt, is capable of forming the active ca.thodic substance. 9· A battery as claimed in claim 3 in which the layer of porous felt is impregnated with ah alljylammonium halide which is soluble in water .and which, by reacting with a perchlorate, is capable of forming an all^lammonium perchlorate and a soluble alkali salt. 10. A battery as claimed" in any of claims 7 ¾o 9 in which the membrane is made of graphite fibres. 11. A battery as claimed in any of claims to $ in which the membrane is made of an electrically conducting metal sheet which has been covered with graphite cement and coked. 12. A battery as claimed in any of claims 1 to 6 in which each bipolar electrode comprises: 'an electrically conducting impermeable membra e having a plurality of graphite or graphitised members thereon forming grooves therebetween; the active cathodic mass being disposed in said grooves and composed of a powdered graphite paste, the active cathodic substance and an inert powder of porous carbon; a latere! retaining ring; and a porous insxilating partition to hold the active cathodic mass in pla.ee. · 13. A battery as claimed in any of claims 7 to 10 or 12 in which the membrane is made of moulded graphite resin.. 1

4. A "battery n clairriod in claim 1> when dependent upon claim 12 in which the membrane is made of impermeable graphite, the grooves being moulded therein. 15· ■ batter;'' as claimed in claim 12 in which the constituents of the active cat odic mass are combined in the following ratio, by weight: powdered graphite paste : active cathodic substance : porous carbon = 3 : 5 : 5· 16. A battery as claimed in claim 12 in which the constituents of the active cathodic mass are combined in the following ratio, by weight: powdered graphite paste : active cathodic substance : poroxis carbon = 1 : 1 : 1. 17. A battery as claimed in any preceding claim in which the ma imu thickness .of tho sine anode is between 3/100 mm and lO/lOO mm. 1G. A battery as claimed in any preceding claim in which the electrolyte has the following ratio: water : zinc bromide = 1 : 1 by weight. 19· A battery as claimed in any preceding claim in which the electrolyt includes bromic acid to. increase the conductivity and the acidity, to reduce or prevent precipitation of zinc hydroxide, to compensate for loss of free bromine and to create a slight insufficiency of zinc compared with the stoichiometric working conditions. 20. A battery as claimed in any preceding claira in which the electrolyte includes a. salt capable of maintaining the conductivity of the electrolyt at the end of the charging process, and of anishing ions which prevent free bromine from dissolving in water. 21. A battery as claimed in claim 20 in which the salt is sodium sulphate. 22. A battery as claimed in any preceding claim in which the additive in the electrolyte to reduce the solubility of the active cathodic substance when the latter is tetranethylaiimionium perchlorate is sodium ' erchlorate. 401 32/2 fc 2J. Λ battery as claimed in any preced5.ng claim in which the electrolyt is composed as follows: ■water 100 parts by weight sine bromide 100 parts by_.weight bromic acid 3 parts by we sodima sulphate 7 parts by v/eight sodium perchlorate 14 parts' b;/ weight. 24. A battery as claimed in any preceding claim in v;hich each cell includes an insulating plastics chassis one wall of which is formed by th bipolar electrode and a plurality of holes through the chassis for supply electrolyte to, and withdrawing electrolyte from, the cell. 2

5. A battery as claimed in claim 24 in which the chassis includes at least one further hole communicating with a pump to evacuate gas formed • in the coll. 2

6. A battery as claimed in claim 24 or 25 ■ including a pump to withdraw electrolyte from the cells and to return the same to the cells, filter means being provided to filter the electrolyte. 2

7. A battery as claimed in claim 26 in which the filter means comprise a plurality of filters each of which has a filter holder within which is at least one porous diaphragm arranged to increase the electrical resista of the flow of electrolyte. 23. A battery as claimed iri claim 26 or 27 in which the pump is a pneumatic pump which communicates with a storin means for storing electrolyte when the battery is not in use, the pneumatic pump, in operat alternately sucling and pumping the electrolyte between the cells and the storing means. 29· A battery substantially as herein described with reference to and as sham in the accompanying drawings.