FR2460547A2 - Battery with two electrolytes - comprises two graphite electrodes a semipermeable separator, with catholyte contg. two cations of several oxidn. state(s) - Google Patents

Abstract

Battery with two electrolytes sepd. by a picoporous membrane as described in the parent patent is claimed where the battery comprises two inert graphite electrodes, the negative electrode bing surrounded by a semipermeable membrane which retains Zn powder around the electrode. Specifically, the electrolyte around the positive electrode contains two ions of different electropositivity and having different levels of oxidn. and is selected from ions which form soluble salts with strong acids, complex cations such as zinc ammonium, cuprammonium, nickel ammonium, cadmium ammonium, ammonium and active carbon. Deposition of either metal in the positive electrode is retarded due to action of the mass on the ionic dissociation of the electrolyte and hence on the ion concn.

Description

The present addition relates to a new application of the semi-permeable membrane according to the main patent, in a double electrolyte battery which has a very high mass energy.

 The anode and cathode compartments of this cell are separated by a picoporous membrane according to the main patent and contain electrolytes around the positive electrode and around the negative electrode which differ from each other.

The battery according to the addition is characterized by the fact that the electrolyte around the positive electrode contains two ions of different electropositivity, which can have various degrees of oxidation, chosen from the following: metal ions such as Fe +++, Cu ++ , Zn ++, Al or any other metal ion forming a soluble salt with strong acids, complex cations such as: Cu (NH3) 4 ++, Zn (NH3) 4 ++, Ni (NH3) 4 ++, cd ( NH3) 4) 4 ++, Cu (H2O) 3NH3 ++, Cu (H # O +) 2 (NH3) 2 ++, Cu (H2O) 3 3 Zn (H2O) 3OH +, ammonium ion NH4 and even activated carbon C. The presence of these two ions of different electropositivity has the effect, by the action of the masses on the ionic dissociation of the electrolyte and therefore on the concentration of the ions, and by the redox potential of these ions, to delay the deposition of one of the two metals at the positive electrode: the most electropositive ion whose metal tends to deposit at the cathode remains in solution as long as the degree of oxidation of the least electric ion positive may decrease.

The electrolyte around the positive electrode can thus consist, according to the invention, of a solution - of iron perchloride and zinc (or cupric) chloride (or sulphate) - of cupric chloride (or sulphate) and chloride (or zinc sulfate # - zinc chloride (or cupric) and ammonium chloride.

The most electropositive ion must always be in higher concentration than the least electropositive ion in the starting electrolyte in general, one uses two volumes of a saturated solution of the salt of the most electropositive ion for a volume of a saturated solution of the salt of the least electropositive ion.

The following compositions of the electrolytes are given, by way of examples, around the positive electrode suitable for batteries according to the invention.

Example 1-
Two volumes of a saturated solution of C12Cu and one volume of a saturated solution of Cl3Fe.

Example 2
Two volumes of a saturated solution of C13Fe and one volume of a saturated solution of C12Zn.

Example 3
Two volumes of a saturated solution of C12Cu (or SO4Cu) and one volume of a saturated solution of C12Zn (or SO4Zn)
Example 4
Two volumes of a saturated solution of C12Cu (or C12Zn) and one volume of a saturated solution of C1NH4.

 The electrolyte around the negative electrode is constituted, in the batteries according to the addition, by a strong base (soda, potash, etc.) or by ammonium chloride.

The electrodes are unassailable, in graphite for example.

The negative electrode is surrounded by a conventional semi-permeable membrane which retains zinc powder around the electrode.

The battery according to the invention has the following advantages - Only the zinc powder around the negative electrode wears out, and must be
renewed - The mass energy of this battery is very high: around 200 W-hour / kilo.

The batteries according to the invention therefore provide a lot of energy for a minimum weight and can be used for example in electric vehicles.

 FIG. 1 schematically represents a battery according to the invention.

 The graphite negative electrodes (1) are located in a pocket constituted by a semi-permeable membrane (2) containing zinc powder (3).

The positive electrode (4) of graphite immerses in the positive electrolyte (5), the composition of which is the subject of the invention.

The picoporous membrane (6) according to the main patent separates the positive electrolyte from the negative alkaline electrolyte (7).

 FIG. 2 represents a battery according to the invention comprising a series of compartments (1) containing the alkaline electrolyte, into which the negative electrodes (not shown) are immersed surrounded by a semi-permeable membrane (2) which retains the powder of zinc (3) which is recharged in the upper compartment (4). The picoporous membranes (5) separate the alkaline electrolyte (1) from the anode compartment from the electrolyte which is the subject of the invention (6) located in the cathode compartment into which the positive electrodes (not shown) are immersed. ).

 In (7) are shown filling tubes of the anode and cathode compartments, and in (8) ventilation openings.

 The ease with which the batteries according to the invention can be recharged chemically, by adding zinc powder in (3) and by renewing the electrolytes by the tubes (7), and the high specific energy of these batteries means that they suitable for many applications and in particular for electric vehicles.

Claims (4)

1. Battery with two electrolytes separated by a semi-permeable picoporous membrane according to claim 1 of the main patent, comprising two unassailable graphite electrodes, the negative electrode being surrounded by a semi-permeable membrane which retains zinc powder around of the electrode, the battery being characterized in that the electrolyte around the positive electrode contains two ions of different electropositivity and which can have several degrees of oxidation, chosen from the following metal ions which form soluble salts with the strong acids, complex cations such as ammonium cations of zinc, copper, nickel, cadmium, ammonium ion and activated carbon. 2. Battery according to claim 1, characterized in that the metal ions of different electropositivity are chosen from the following Cu, Zn ++, Al +++, Fe +++. 3. Battery according to claim 1, characterized in that the complex cations of different electropositivity are chosen from the following Cu (NR3) 4 ++, Zn (NH3) 4 ++, N + i + (NH3) 4 ++, Cd (N} # + 3) 4 ++, Cu (H20) 3NH3 ++, Cu (H20) 2 (NH3) 2 ++, Cu (H20) (N113) 3 ++, Zn (H2O) 4, Zn (H2O ) 3OH 4. Battery according to one of claims 1 to 3 characterized in that the electrolyte around the positive electrode contains a higher concentration of the most electropositive ion, and preferably two volumes of a saturated solution of the salt of the most electropositive ion for a volume of a saturated solution of the salt of the least electropositive ion.