BATTERY WITH A SPECIFIC LIQUID CATHODE WHICH MAY OPERATE AT HIGH TEMPERATURES

Abstract

The invention relates to a liquid cathode cell including: a calcium anode; an electrolyte containing a sulphurous or phosphorous oxidising solvent and at least one salt; and a cathode containing, as an active material, a compound that is identical to the aforementioned oxidising solvent. The invention is characterised in that the salt is a strontium salt which is present in a concentration of from 1.15 mol.Math.L.sup.1 to 3 mol.Math.L.sup.1.

Claims

1. A battery with a liquid cathode comprising: a calcium anode; an electrolyte comprising a sulfur-containing and/or phosphorus-containing oxidizing solvent and at least one salt; a cathode comprising, as an active material, a compound identical with the oxidizing solvent; wherein the salt is a strontium salt present at a concentration ranging from 1.15 mol.Math.L.sup.1 to 3 mol.Math.L.sup.1.

2. The battery with a liquid cathode according to claim 1, wherein the cathode comprises a porous matrix in a carbonaceous material.

3. The battery with a liquid cathode according to claim 2, wherein the carbonaceous material is selected from carbon blacks, acetylene blacks, graphite, carbon fibers or mixtures thereof.

4. The battery with a liquid cathode according to claim 2, wherein the porous matrix is associated with a current-collecting substrate, said substrate being in a metal material.

5. The battery with a liquid cathode according to claim 1, wherein the oxidizing solvent is a sulfur-containing solvent, comprising one or several chlorine atoms; a non-chlorinated sulfur-containing solvent; or a phosphorus-containing solvent and optionally sulfur-containing solvent comprising one or several chlorine atoms.

6. The battery with a liquid cathode according to claim 5, wherein the sulfur-containing solvent comprising one or several chlorine atoms is selected from thionyl chloride (SOCl.sub.2), sulfuryl chloride (SO.sub.2Cl.sub.2), disulfur dichloride (S.sub.2Cl.sub.2), or sulfur dichloride (SCl.sub.2).

7. The battery with a liquid cathode according to claim 5, wherein the non-chlorinated sulfur-containing solvent is sulfur dioxide.

8. The battery with a liquid cathode according to claim 5, wherein the phosphorus-containing and optionally sulfur-containing solvent comprising one or several chlorine atoms is selected from phosphoryl trichloride (POCl.sub.3), or thiophosphoryl trichloride (PSCl.sub.3).

9. The battery with a liquid cathode according to claim 1, wherein the oxidizing solvent is thionyl chloride (SOCl.sub.2).

10. The battery with a liquid cathode according to claim 1, wherein the strontium salt is a salt comprising a strontium cation Sr.sup.2+ associated with a halogenated anion based on an element selected from aluminium, gallium, boron, indium, vanadium, silicon, niobium, tantalum, tungsten, or bismuth.

11. The battery with a liquid cathode according to claim 10, wherein the halogenated anion is based on chlorine.

12. The battery with a liquid cathode according to claim 1, wherein the strontium salt is the strontium tetrachloroaluminate salt Sr(AlCl.sub.4).sub.2.

13. The battery with a liquid cathode according to claim 1, wherein the strontium salt results from the reaction in situ of a Lewis acid and of a Lewis base.

14. The battery with a liquid cathode according to claim 1, wherein the electrolyte comprises one or several additives selected from hydrofluoric acid (HF), SO.sub.2, GaCl.sub.3, BiCl.sub.3, BCl.sub.3, GaCl.sub.3, InCl.sub.3, VCl.sub.3, SiCl.sub.4, NbCl.sub.5, TaCl.sub.5, PCl.sub.5 or WCl.sub.6.

15. The battery with a liquid cathode according to claim 1, which is a concentric electrode structure battery or a battery with a spiral electrode structure.

16. The battery with a liquid cathode according to claim 3, wherein the porous matrix is associated with a current-collecting substrate, said substrate being in a metal material.

Description

SHORT DESCRIPTION OF THE FIGURES

[0089] FIG. 1 is a diagram illustrating the operating principle of a battery Li/SOCl.sub.2.

[0090] FIG. 2 is a sectional view of a battery with so-called concentric electrode structure according to the invention.

[0091] FIG. 3 is a sectional view of a battery with a so-called spiral electrode structure according to the invention.

[0092] FIG. 4 is a discharge curve, i.e. a curve illustrating the time-dependent change in the battery voltage U (in mV) versus time t (in hours) at constant current (17 mA) and at 210 C. with three batteries comprising an electrolyte according to the invention (curves c, d and e), and with two batteries comprising an electrolyte not compliant with the invention comprising a salt Sr(AlCl.sub.4).sub.2 at 0.8 M and at 1 M (curves a and b).

[0093] FIG. 5 is a discharge curve, i.e. a curve illustrating the time-dependent change in the battery voltage U (in mV) versus time t (in hours) at constant current (17 mA) and at 210 C. with two batteries comprising an electrolyte according to the invention (curves a and b).

[0094] FIG. 6 is a discharge curve with a pulsed current at 210 C. with the following periodic current pulses: 9 s/5 mA-1 s/60 mA obtained with a battery according to the invention as defined in example 1.

[0095] FIG. 7 is a discharge curve at constant current (4 mA) and at 250 C. with two batteries comprising an electrolyte according to the invention (curves a and b).

[0096] FIG. 8 is a discharge curve at constant current (4 mA) at 20 C. with a battery according to the invention, as defined in example 1.

[0097] FIG. 9 is a discharge curve with a constant current (17 mA) at 20 C. with a battery according to the invention as defined in example 1.

[0098] FIG. 10 is a discharge curve illustrating the time-dependent change in the battery voltage U (in mV) versus time (in hours) at constant current (17 mA) and at 250 C. with a battery comprising an electrolyte according to the invention as defined in example 2.

[0099] FIG. 11 is a pulsed discharge curve at 210 C. with the following periodic current pulses: 9 s/5 mA-1 s/60 mA with the battery according to the invention as defined in example 2.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

Example 1

[0100] The object of this example is to demonstrate the performances of the batteries according to the invention in a wide range of temperatures, and notably at high temperatures, and in particular at temperatures above 200 C. (and more specifically at 210 C. and 250 C. in this example).

[0101] The tested batteries are of a so-called concentric electrode structure, as illustrated in FIG. 2 enclosed as an annex.

[0102] In a first test, discharge curves are determined, i.e. curves illustrating the time-dependent change in the battery voltage U (in mV) versus time (in hours) at constant current (17 mA) and at 210 C. with three batteries comprising an electrolyte according to the invention, i.e.: [0103] a battery comprising an electrolyte comprising 1.15 M of Sr(AlCl.sub.4).sub.2 in thionyl chloride (curve c); [0104] a battery comprising an electrolyte comprising 1.32 M of Sr(AlCl.sub.4).sub.2 in thionyl chloride (curve d); [0105] a battery comprising an electrolyte comprising 1.5 M of Sr(AlCl.sub.4).sub.2 (obtained by mixture of 1.5 M of SrCl.sub.2 and of 3M of AlCl.sub.3) in thionyl chloride (curve e);

[0106] and with two batteries comprising an electrolyte non-compliant with the invention, i.e.: [0107] a battery comprising an electrolyte comprising a salt Sr(AlCl.sub.4).sub.2 at 0.8 M in thionyl chloride (curve a); [0108] a battery comprising an electrolyte comprising 1 M of Sr(AlCl.sub.4).sub.2 in thionyl chloride (curve b).

[0109] These discharge curves are illustrated in FIG. 4 enclosed as an annex.

[0110] For the batteries according to the invention, it is observed that the discharge voltage remains greater than 3 V for more than 3 hours and greater than 2.5 V for more than 7 hours from a concentration of 1.15 M and remains greater than 3V for more than 5 hours and greater than 2.5 V for more than 10 hours for a concentration of 1.5 M, while, for batteries non-compliant with the invention, there is a very significant decrease in the voltage as soon as the first hours and, notably a voltage already less than 2 V after 4 hours of use for a concentration of 0.8 M and less than 3 V after 2 hours of use for a concentration of 1 M.

[0111] This confirms the efficiency of the batteries according to the invention at high temperatures, as soon as the salt concentration is of at least 1.15 M.

[0112] Additionally, the determination of the discharge curve was carried out under the same conditions as those mentioned above, for a battery according to the invention comprising an electrolyte comprising a salt Sr(AlCl.sub.4).sub.2 at 2 M in thionyl chloride which is compared with a discharge curve with another battery according to the invention comprising an electrolyte comprising a salt Sr(AlCl.sub.4).sub.2 at 1.5 M in thionyl chloride.

[0113] These curves are transferred onto FIG. 5 (respectively curve a) for the battery at 2M and curve b) for the battery at 1.5 M.

[0114] For the battery at 2M, a voltage greater than 3 V is observed for 11 hours.

[0115] In a second test, the discharge curve is determined under a pulsed current at 210 C. with the following periodic current pulses: 9 s/5 mA-1 s/60 mA with the aforementioned battery according to the invention (battery at 1.5 M), this curve being illustrated in FIG. 6. The pulse voltage remains greater than 2 V for 9 hours, which validates the use of this type of battery for a pulsed application. It should be noted that the voltages with a current of 5 mA are high and greater than 3 V.

[0116] In a third test, the discharge curves at constant current (4 mA) and at 250 C. are determined with two batteries comprising an electrolyte according to the invention (1.5 M as defined above and a battery comprising an electrolyte comprising a salt Sr(AlCl.sub.4).sub.2 at 3 M in thionyl chloride), these curves being illustrated in FIG. 7 (curve a for the battery at 3M and curve b for the battery at 1.5 M).

[0117] For both of these batteries, it may be observed that the discharge voltage remains greater than 2 V for more than 48 hours, which is very interesting at such a temperature.

[0118] The composition of the electrolyte gives the possibility of maintaining a high voltage and obtaining a discharge profile at 250 C., characteristic of the technology of primary batteries with a liquid cathode.

[0119] In a fourth test and in a fifth test, were determined respectively: [0120] the discharge curve at constant current (4 mA) at 20 C. with a battery according to the invention (the battery with a salt concentration of 1.5 M), this curve being illustrated with FIG. 8; [0121] the discharge curve at constant current (17 mA) at 20 C. with a battery according to the invention (the battery with a salt concentration of 1.5 M), this curve being illustrated with FIG. 9.

[0122] At a low current, the voltage remains greater than 2 V for more than 160 hours and with a high current, the voltage remains greater than 2 V for more than 12 hours.

[0123] This confirms the possibility of using the batteries of the invention both at room temperature and at a high temperature, as demonstrated with the preceding tests.

Example 2

[0124] The object of this example is to demonstrate the performances of the batteries according to the invention at high temperatures, and in particular at temperatures above 200 C. (and more specifically at 210 C. and 250 C. in this example).

[0125] The tested batteries are of a so-called spiral electrode structure, as illustrated in FIG. 3 enclosed as an annex.

[0126] In a first test, the discharge curve is determined, i.e. the curve illustrating the time-dependent change in the battery voltage U (in mV) versus time (in hours) at constant current (17 mA) and at 250 C. with a battery comprising an electrolyte according to the invention, i.e. 1.5 M of SrCl.sub.2 and 3M of AlCl.sub.3 (i.e. 1.5 M of Sr(AlCl.sub.4).sub.2) in thionyl chloride SOCl.sub.2, this curve being illustrated in FIG. 10.

[0127] It is observed that the discharge voltage remains greater than 2 V for more than 10 hours.

[0128] In a second test, the discharge curve under a pulsed current at 210 C. with the following periodic current pulses: 9 s/5 mA-1 s/60 mA is determined with the aforementioned battery according to the invention, this curve being illustrated in FIG. 11.

[0129] The pulse voltage is higher during the use of concentric batteries, which validates the use of this type of battery for a pulsed application. As the surfaces of the electrodes are larger, the voltages are higher (lower current densities). The batteries with spiral electrodes are therefore more adapted to applications having a need for power (i.e. for strong currents).