FR2586863A1 - ELECTRIC ACCUMULATOR. - Google Patents

Abstract

NON-AQUEOUS ELECTROLYTE ELECTRIC ACCUMULATOR, CONSISTING OF THIONYL CHLORIDE OR SULFURYL CHLORIDE AND A METAL SALT DISSOLVED IN AND ANODED OF A METAL FROM GROUPS 1 AND 2 OF THE PERIODIC TABLE OR AN ALLOY OF THESE, HAVING A DELAYED ACTION REDUCED WHEN THE ELECTROLYTE CONTAINS SE0 OR TE0 IN CONCENTRATIONS UP TO SATURATION.

Description

Electric accumulator.

  The present invention relates to an electric battery with a non-aqueous electrolyte / cathode, comprising thionyl chloride or sulfuryl chloride and a metal salt dissolved therein, and an anode of a metal from group 1 or 2 of the Periodic Table or a

of their alloys.

  A typical accumulator of this kind is the so-called lithium accumulator in which the electrolyte / cathode is thionyl chloride or sulfuryl chloride containing lithium aluminum chloride (LiAlC14) dissolved state, and in

which the anode is made of lithium.

  Accumulators of this kind have the disadvantage that, during storage, a passivation layer is formed on the surface of the metal of the anode which causes what is called a delayed action (AR), ie a low capacity of the accumulator, at

departure, to bear a load.

  Many attempts have been made to resolve this problem, but none have been able to eliminate the delayed action without increasing

  considerably either self-discharge or costs. The temptati-

  These have been concentrated on accumulators in which the anode is made of lithium, and in what follows, we will mention these attempts in

  compared to an accumulator of this kind, but in principle, the problem

  me is the same when the anode is in one of the other metals of groups 1 and 2 of the Periodic Table or alloys thereof, which are placed high in the table of electrochemical reaction potentials, since the action delayed is due to the formation of a layer of metal chloride on the surface of the anode, layer which prevents the starting of the reaction producing the tension between the anode and thionyl chloride or sulfuryl chloride. This layer of metal chloride grows over time, and if the battery has been stored for a very long time, it can be so large that

the battery cannot be used.

  We tried to solve the problem by putting sulfur dioxide (SO2) in the electrolyte, which produced a good effect, both with saturated electrolytes and with unsaturated electrolytes of lithium chloride (LiCl), but this effect is only maintained at room temperature because the addition of SO2 causes a

  irreversible passivation if the battery is exposed to temperatures

  tures above about 40C. In addition, self-discharge increases considerably. A second attempt was to replace the LiAlC14 salt traditionally used by the Li2B10Cl10 and Li2B12Cl2 salts. Such an electrolyte change results in improvements in AR, but increases electrolyte costs significantly, and results in a less stable, lower capacity electrolyte.

to bear a load.

  A third attempt was to replace the salt LiAlC14 with the product of the reaction of NbC15 on Li2S or Li20. This also results in improvements in the AR properties of the accumulator, but so far this has only been verified in accumulators which have been stored for a short time, seen

that the attempt is recent.

  Other additions to electrolytes, which have resulted

  an improvement in AR, are the additions of the salts SbC15 and GaC14.

  However, they do not in themselves provide a solution

satisfying the AR problem.

  Finally, we tried to cover the anode with lithium, but this

  method is neither convenient nor very effective.

  Therefore, there is a need for an electric accumulator of the type discussed here, which presents no problem.

  action that does not have the disadvantages of self

  discharge or of a weak capacity to support a load.

  The present invention provides such an accumulator, which is characterized in that the electrolyte contains SeO2 or

  TeO2, in a concentration up to saturation.

  In addition to the fact that, using selenium dioxide, or tellurium dioxide, an effect is obtained which is not accompanied by the drawbacks mentioned above and linked to sulfur dioxide, selenium dioxide and tellurium dioxide have the advantage over sulfur dioxide that they are less aggressive vis-à-vis the glass seals of the accumulator, so that

  leaks that can occur when an accumulator contains SO2.

  A specially advantageous effect is obtained when the electrolyte / cathode also contains up to 0.9 M of LiNbCl6 or LiTaCl6, since these compounds reduce the self-discharge of the elements without affecting the improvements in AR achieved. A likely explanation for this may be that LiNbC16 or LiTaCl6 forms a stable passivation layer on lithium which conducts lithium ions. As the growth of LiCl on this layer is simultaneously prevented, a double effect is obtained where the elements have a very low self-discharge in ee

  as long as they are largely APR free.

  The invention is illustrated by the following examples with reference

in the accompanying drawings.

EXEIPLE 1

  Some elements are prepared with lithium as anode, thionyl chloride (S0C12) with 1.8 M of LiAlC14 dissolved in it

  as electrolyte / cathode, and carbon as a collector

  rant. The following amounts of SeO2 are added to the thionyl chloride: Element of type 1: 0% (standard type of element) Element of type 2: 0.4% by weight of SeO2

  Type 3 element: 0.8% by weight of Se02.

  In addition, a type 4 element is prepared which contains in the electro-

  1.20 M lyAlC14 lyte; 0.60 M AlCl3; and SeO2 in quantity

going to saturation.

  The elements are then stored under the following conditions: Storage A: 2 weeks at 21'C Storage B: 2 weeks at 70'C Storage C: 5 weeks at 45 C Storage D: 1 month at 70'C

  and then we measure their capacity and their AR.

  Figures 1 to 4 of the accompanying drawings show the results of the AR measurements, the numbers shown on the corresponding graphics

said types of elements.

Figure 1 shows

2 weeks at 21'C.

Figure 2 shows

2 weeks at 70'C.

  Figure 3 shows weeks at 45 C. Figure 4 shows

1 month at 70C.

  After discharge on the results obtained the results obtained the results obtained the results obtained found the capacities after storage during after storage during after storage during after storage during following:! Type Elh (V) Capacity (Ah) Element storageI [

1 3.33 4.94

- 2.47 5.20

3 3.47 5.36

4 3.42 5.05

1 3.00 5.50

2 3.40 5.23 C

3 3.43 5.47

1 2.88 5.18

2 3.43 4.85

3 3.43 4.90

* u

EXAMPLE 2

  Six elements are prepared with lithium as anode, thiouyl chloride as electrolyte / cathode and carbon as current collector; two of these elements contain 1.8 M of LiAlC14 dissolved in thionyl chloride; two other of these elements comprise 1.8 M of LiAlC14 and 0.8% by weight of SeO2, dissolved in thionyl chloride; and the last two contain 1.8 M LiAlC14 and 4%

  by weight of SO 2, dissolved in thionyl chloride.

  The elements are then stored for 2 months at 70 "C, in order to

  test for leaks at the glass seal.

The results are as follows:

EXAMPLE 3

  Two elements are prepared with lithium as anode, thionyl chloride as electrolyte / cathode, and carbon as current collector, one of the elements comprising 1.8 M of LiAlCl 2 dissolved in thionyl chloride, the other element comprising 1.7 M of LiAlC14, 0.1 M of LiNbC16, and 0.4% by weight of SeO2, dissolved in the

thionyl chloride.

  The elements are stored for 5 weeks at 45 ° C., after which they are discharged with the following results: Type of element Note 1.8 M LiAlC14 no leak 1.8 M LiAlC14 + 0.8% weight SeO2 no leak 1.8 M LiAlC14 + high leakage after 3 4% weight S02 weeks of storage

EXAMPLE 4

  Two elements are prepared with lithium as anode, thionyl chloride as active cathode, and carbon as current collector, one of the elements comprising 1.8 M of LiAlC14 dissolved in thiouyl chloride (standard element), l other element similarly comprising 1.8 M of LiAlC14, but also being saturated with

TeO2.

  The elements are stored for 15 days at 70 ° C, after which we measure AR. The results of this measurement are shown in Figure 5 of the accompanying drawings, where curve 1 corresponds to the element

  standard, and curve 2 with the element according to the invention.

  Element type Elh (V) Capacity 1.8 M LiAlC14 2.90 5.30 1.7 M LiAlC14 0.1 M LiNbC16 3.35 5.65 0.4 Z weight SeU2

Claims (5)

  1. Electric battery with non-aqueous electrolyte / cathode, comprising thionyl chloride or sulfuryl chloride and a metal salt dissolved therein, and an anode of a metal from groups 1 and 2 of the Periodic Table or an alloy of those -ci, characterized in that the electrolyte contains SeO2 or TeO2 in concentrations up to saturation,   2. Electric battery conforms to claim 1, earacté   risé in that the electrolyte contains from 0.1 to 1.0% by weight of Se02.   3. Electric accumulator according to claims 1 and 2,   characterized in that the electrolyte additionally contains up to 0.9 M LiNbC16 or LiTaC16.   4. Electric accumulator according to claim 3, charac-   terized in that the electrolyte contains from 0.02 1- to 0.30_1 of LiNbCl6 or LiTaC16.   5. Electric accumulator according to claims 1-4,   characterized in that the electrolyte is not saturated with LiClo