FR2474767A1 - PERFECTLY LEAD-ACID BATTERY ACCUMULATOR - Google Patents

Abstract

ACCUMULATOR LESS SUBJECT TO SHORT-CIRCUITING DUE TO REVERSE CHARGE OR SEVERE DISCHARGE. IT INCLUDES A POSITIVE ELECTRODE 25, A NEGATIVE ELECTRODE 23, AN ELECTRICALLY NON-CONDUCTIVE POROUS SEPARATOR 26, PLACED BETWEEN THE POSITIVE AND NEGATIVE ELECTRODES, A BOX 15 CONTAINING THE ELECTRODES AND THE SEPARATOR, AND AN ELECTROLYTE WHICH CAN BE PLACED INSIDE THE CASE AND IN CONTACT WITH THE ELECTRODES AND THE SEPARATOR AND AN INERT POROUS SHORT-CIRCUIT INHIBITOR 22 PLACED BETWEEN THE NEGATIVE ELECTRODE 23 AND THE SEPARATOR 26 AND AS CONTIGUOUS TO THEM. APPLICATION TO LEAD OR ZINC ACCUMULATORS.

Description

The present invention relates to electric accumulators

  trochemicals, and more particularly a new accumula-

  sealed lead-acid which shows superior performance

  and is less subject to short-circuiting due to load reversal or severe discharge.

  The fully sealed lead-acid accumulator

  kills a significant advance compared to the accumulator lead-

  well known acid. It is cylindrical and includes

  a spiral wound plate to obtain a den-

  high energy density and low internal impedance;

  and it can be used, that is to say the loading and unloading

  ger in any position. These accumulators

  conventionally take positive and negative lead plates spaced apart from each other, having the structure of a grid. We fill this structure with

  active materials to form positive electrodes (dioxygen

  of lead) or negative (spongy lead). A thin porous separator is interposed between the plates, and the plate assembly is wound into a compact, solid cylindrical form. The separator electrically isolates the plates and also behaves like an effective wick that retains the electrolyte of the accumulator (an aqueous solution of sulfuric acid) and distributes it evenly

  in the active area. The thin separator, extremely

  reux establishes a short ionic path between the plates and allows the rapid diffusion of the electrolyte, these factors

  all contributing to the ability of the accumulator to

  charge at high speeds. The conventional accumulator also generally includes means, for example, excess negative plate material, to minimize formation of gas in the accumulator and a resealable opening to relieve internal pressure.

  in the accumulator in case unintended gases are formed

  raient. Although the accumulator described above represents

  significant progress compared to lead-acid accumulators

  acid of the prior art, it is desirable to further improve its performance and extend the duration of its cycle of use especially when subjected to extreme conditions. For example, when a lead-acid accumulator is left in open circuit, it occurs

  a slow electrochemical discharge, the speed of

  discharge depending on the temperature of the accumulator and

  of his state of charge. If a battery is allowed to

  completely discharge, that is to say until

  Since all the sulfate ions of the electrolyte have reacted with the materials constituting the plates, the lead sulphate becomes slightly soluble in the highly diluted electrolyte and is free to diffuse into the separator between the plates. If you try to recharge the battery under these conditions, lead dendrites may form

  in the separator between the plates, short-circuiting possibly

  the accumulator and ending its useful life. In the same way, when for one reason or another, a discharged lead-acid accumulator is connected to a load

  by reversing it, the accumulator will accept a charge (the

  that positive becomes a negative plate and vice versa), but risks being short-circuited by lead deposits

  metallic lead and sulphate of lead existing in the sepa-

  tor. Moreover, it has been discovered that the winding of the assembly

  known battery separator plates had cer-

  some difficulties. More particularly, in the frabrica-

  electrolytic accumulators or batteries,

  puts the materials constituting the negative and posi-

  This is in the form of strips which are then cut to the desired length for the battery plates and wound with a material forming the separator to form a coil. The spool is then inserted into a preformed cylindrical container. The electrolyte is added

  in the container, and seal it.

  sealed emulator. The coiled positive plate is connected to the positive terminal and the coiled negative plate to the negative terminal. In a conventional manner, the plates and separators are wound in the composite assembly wound around a mandrel with a transfer roller or by

  contact the inner surface of a cylindrical winding set

  only with one side of the coil that is wound. However, this method has the disadvantage of directly applying

  by the roll to the strips that wind the forces ne-

  necessary for winding. Tensile forces apply

  separators when the tree pulls the separa-

  and the plates in the wound composite assembly. com-

  the separators have a low tensile strength, these winding forces can damage and /

  or break the separators, and lead to a short coil

  circuit, which of course has an adverse effect on the

overall quality of the accumulator.

  The present invention develops a new accumula-

  improved rechargeable sealed lead-acid

  takes an external assembly consisting of positive and negative plates spaced from one another, a porous thin separator placed between the positive and negative plates, and a

  short-circuit inhibitor interposed between the negative plate

  tive and the separator. In the recommended embodiment of this invention, the plate-separator assembly is

  wound in a coil in such a way that

  short-circuit bitor is contiguous to each of the main surfaces of the negative plate; a separator is contiguous to each of the short circuit inhibitors; and

  the positive plate is contiguous to one of the separa-

  tors. In accordance with the present invention, each of the

  short-circuit hibitors is formed of a fine woven fabric, woven or not, consisting of a polymer fiber resistant to oxidation and acids such as polyester, polypropylene, etc. which can be combined or not with

  a filler of sintered polymer. The short-term inhibitor

  circuit may have a thickness of between about 0.0229 and 0.254 mm, and preferably about 0.0305 mm a basis weight (g / m2) of between about 21.53 and

  35.89, and preferably about 23.92, a density of

  apparent density in g / cm3 between about 0.64 and

  0.78 and preferably about 0.78 and a similar porosity

  taken between about 40 and 50%. It should be noted that although the recommended location of the short circuit inhibitor

  is, as noted above, on the

  than the negative of the accumulator, it can be placed anywhere

  te o in the composite plates-separators. Each separat-

  which may comprise one or more layers may conventionally be made of non-woven glass microfibers mat. It should be understood, however, that other types of commonly used separators can also be used. The present plate-separator-inhibitor assembly of

  short circuit is contained in a housing that also contains

  the electrolyte, which is conventionally constituted by a solu-

  aqueous sulfuric acid. The case includes, well

  sure, a pair of terminals, each connected to a

positive or negative.

  It should be noted that although the present arrangement has been described in the case of a lead-acid accumulator, it is also possible to use it in

zinc electrodes.

  The remainder of the description refers to the figures

  represented respectively: Fig. 1, a sectional view, in perspective of an element

  accumulator manufactured in accordance with the present invention.

tion,

  Fig. 2, a plan view, partially exploded of the

  the accumulator element of Figure 1; and 3, a diagram schematically showing the circuit-separator-shortcircuit inhibitor circuit of the present invention prior to winding it into a coil

cylindrical.

  Referring to FIGS. 1 and 2, the electrochemical accumulator of the present invention comprises a

  an inner mount 20 which includes a negative electrode plate

  23, one, first and second short-term inhibitors

  circuit 22, each placed contiguously to one of the main surfaces of the negative electrode plate 23 first and second separators 26, each contiguous to one of the short-circuit inhibitors 22

  and a positive electrode plate 25 placed continuously

  to one of the separators 26. As shown on

  the figures, the recommended embodiment includes a

  spiral wound 20, but it will be understood that a plate-separator-inhibit

  flat short circuit in accumulators which

  close a gelled electrolyte system. When the

  The accumulator is of the lead-acid type, the plate

  negative trode 23 and the positive electrode plate 25 are constituted by lead metal grids which are

  cut into strips. We fill these grids with the

  active materials to form a negative electrode 23 (lead

  spongy) and a positive electrode (lead dioxide).

  As mentioned above, it is also possible to use

  the invention with accumulators with zinc electrodes,

  In this particular case, the electric plates will be

  Positive and negative trodes of the accumulator in a way

  different, in accordance with known practice.

  In accordance with the present invention, each

  The short-circuiting device 22 is formed of an inert fabric, of fine mesh, woven or not, constituted by a fiber of

  polymer resistant to oxidation and acids as a

  lyester, a polypropylene, etc ... that can be combined or

  not with a sintered polymer charge. In the realization

  recommended embodiment of the invention, the short-term

  circuit 22 are of polyester and have a thickness of between about 0.0229 and 0.254 mm, and preferably about 0.0305 mm, a basis weight (g / m2) of between about 21.53 and 35.89, and preferably about 23.92,

  a bulk density (in g / cm3) between

  0.64 and 0.78, and preferably about 0.78; and

  a porosity between about 40 and 50%, and pre-

  Also, it is preferred that the short-circuit inhibitors 22, are longer than the plates 23 and 25 and the separators 25, to have extensions 27 on the short-circuit inhibitors. (see Figure 3), the role of these extensions being described below. The separators 26 are formed of a thin, highly porous insulating material which together with the short-circuit inhibitors 22 completely electrically isolates the positive and negative electrode plates 25 and 23. As previously indicated, the separators 26 are - as an effective wick that retains the electrolyte from the accumulator and distributes it evenly in the active area. The porous separators 26 and the inhibitors 22 establish a short ion path between the plates 23

  and 25 and allow rapid diffusion of the electrolyte.

  The separators 26 are preferably made of a mat of

  micro-fibers of non-woven glass, but one can also u-

  use other types of common separators. Of

  Moreover, as shown in Figures 1 and 2, each

  may include one or more layers 23, and

example 4 layers.

  According to the invention the assembly can be wound

  20 spiral electrodes using booster apparatuses.

  automatic or manual belt hoeing, or a winding process using a tree, such as the one

  shown schematically in Figure 3. It is more

  recommended as shown in Figure 3 (and as previously indicated) that

  short circuit 22 are longer than the electro-magnetic

  23 and 25 and that the separators 26 to have

  27 short-circuit inhibitors.

  when the assembly 20 is wound up, the shaft 24 pulls on the extensions

  27, which also has the effect of

  electrode plates and separators. As the inhibitors

  22 have a sufficient tensile strength to withstand the tensile forces exerted by the shaft during the winding of the electrode strips, separators and

  short-circuit inhibitors, the indi-

  previously, due to the direct application of the

  the fragile separators, which gener-

  usually a very low tensile strength.

  If we refer again to Figures 1 and 2, the

  The wound electrode electrode 20 of the invention is encased in a cylindrical casing 15, which preferably comprises an inner member 12 formed of an electrically non-conductive material, for example a chemically stable polypropylene. The housing 15 also includes an outer metal member 11 enclosing the inner member 12, providing strength and mechanical rigidity. The outer element He

  can conventionally be aluminum or steel. By using

  In a housing 15 composed of inner and outer elements 12 and 11, respectively, the rate of diffusion of gases through the wall of the housing is minimized and

  in practice, eliminates any loss of water from the electrolyte.

  The housing 15 also includes an outer cover 13

  and a pair of terminals 14 and 16. Terminals 14 and 16

  pour the outer cover 13, and each of them is

  electrically connected to the positive plate 25 or to the negative plate 23 inside the housing 15. The housing 15 can

  also include a ventilation mechanism, which is safe, reseal-

  lable 17 which allows the safe evacuation of gases that

  can be formed under exceptional operating conditions.

  like an overload rate. We add

  preferably the electrolyte, which is conventionally

  by an aqueous solution of sulfuric acid in the

  pressure housing. The concentration of acid in the

  The amount of battery charge depends on the state of charge, with the highest concentration when the battery is fully charged and the lowest when the battery is discharged. The quantity of electrolyte used in the accumulator is chosen so as to allow efficient use of the active materials constituting the plates, while avoiding the accumulation of free electrolyte, that is to say

  not fixed by the electrode plates 23 and 25, the sepa-

  26 and the short-circuit inhibitor layers 22.

  As previously indicated, under normal conditions

  In practice, there is no evidence of water loss from the electrolyte. However, a small part of the water may temporarily participate in the production of

gas during an overload.

  The following examples are presented to compare the

  results obtained when tests of accumula-

  classifiers and accumulators containing

  preventing short circuits in accordance with the invention.

Example 1

  Accumulators have been constructed for testing in accordance with the recommended embodiment of this

  invention, that is to say by incorporating layers of inhibi-

  polyester short-circuiting devices. We filled some

  accumulators with electrolyte in a conventional manner

  that, and the electrolyte was forced under pressure into

  other accumulators to increase its speed of penetration

  tration. After filling the accumulator we have

  pressure. Each of the short circuit inhibitors had a thickness of between about 0.0229 and 0.254 mm; a basis weight of between about 21.53 and 89 g / m 2, a bulk density of about 0.64 to 0.78 g / cm 3 and a porosity of about 40 to 50%. In addition, control accumulators, that is accumulators not

  not including the polyester short circuit inhibitors of the pre-

  invention, filling some of the control accumulators with electrolyte in the conventional manner, and penetrating the electrolyte under pressure into the

  other control accumulators, as previously described.

  As a result, all the accumulators according to the invention and all the test accumulators were subjected to an inversion test which consisted in discharging the accumulators which had just been manufactured at a speed 250 mA in 24 hours.This had the effect of completely discharging the batteries, and tend to reverse their polarity. The

  control accumulators, whatever the way in which

  introduced the electrolyte, tended to produce shortcircuits by metallic lead

  lead sulphate in the separators, 90% of accumula-

  warning lamps being the seat of short circuits between the electrodes. None of the accumulators according to the invention produced short circuit. In addition accumulators

  according to the invention in which the

  c474767 the electrolyte under pressure did not show traces of

  lead sulphate in separators or in inhibitors

short circuit.

Example 2

  Accumulators containing inhibitors have been prepared.

  short circuit circuitry of the present invention by

  to penetrate the electrolyte under pressure, reducing the pressure once the accumulators are full. In all accumulators, short-circuit inhibitors had the same thickness, weight, bulk density and porosity as accumulators

  according to the invention of Example 1. In addition, there is also

  prepared accumulators, that is to say,

  accumulators that do not contain short-term inhibitors

  circuit of the present invention. The accumulations were

  cycle of 480C, each cycle comprising a period of

  charging time of 18 hours on a constant voltage of 2.45 volts, and a discharge of 1.8 amps with a voltage

  1.4 volt cutoff. Knowing that we define "the failure

  launches "as a capacity drop to half the capacity

  1.3 amps at the pre-charge discharge rate.

  the accumulators according to the invention lasted,

  that is to say have not suffered "failure" for a period of time

  twice as long as control accumulators.

  In summary, the present invention develops an accu-

  an improved electrochemical emulator comprising

  short-circuit bitters in the composite electro-plates

  separators. This accumulator prolongs the time that

  before the occurrence of a permanent failure of the accumula-

  because of the short-circuit caused by deposits of dendri-

  lead in insulators of plates (separators) when the accumulator is subjected to abusive conditions,

  for example, overdischarge and reversal of the accumulator.

  In addition, the accumulator of the invention has a duration

  of the utilization cycle significantly higher than that of the

  known accumulators. In addition, the accumulator of the present invention has good resistance to damage.

  of the accumulator separator during the winding of the

  ge separator plates the relatively resistant polyester short-circuit inhibitors constituting the part of the assembly that supports the most important part of the forces

traction during winding.

Claims (16)

R E V E N D I C A T I 0 N S   1 - Electrochemical accumulator comprising an electrolyte   positive trode 25, a negative electrode 23, an electrically non-conductive porous separator 26, placed between the positive and negative electrodes, a housing 15 containing the electrodes and the separator, and an electrolyte which can be placed inside the housing and contact with   electrodes and the separator characterized in that an inhibit   porous inert short circuit 22 is placed between the   the negative electrode 23 and the separator 26 and in a manner tigger to them.   2 - electrochemical accumulator according to claim 1, characterized in that the short-circuit inhibitor 22 is constituted by a mesh fabric formed of a fiber of   polymer resistant to oxidation and acids.   3 - Electrochemical accumulator according to the claim   1 or 2, characterized in that the short-term inhibitor   Circuit 22 is a woven mesh fabric.   4 - improved electrochemical accumulator according to claim 1 or 2 characterized in that the inhibitor   short circuit 22 is a nonwoven fabric.   - Improved electrochemical accumulator according to claim 1 or 2 characterized in that the inhibitor of   short circuit 22 comprises a filler of sintered polymer.   6 - improved electrochemical accumulator according to claim 1 or 2, characterized in that the inhibitor   short circuit 22 is formed of polyester.   7 - electrochemical accumulator according to claim 1 or 2, characterized in that the short-circuit inhibitor 22 is polypropylene.   8 - Electrochemical accumulator according to the claim   1 or 2, characterized in that the short-term inhibitor   circuit 22 has a bulk density of   be about 0.64 and 0.78 grams per cubic centimeter and   a porosity of between about 40 and 50%.   9 - Electrochemical accumulator according to any one   than preceding claims, characterized in that the   separator 26 is a fiberglass element. e474767 he   - Electrochemical accumulator according to the claim   9, characterized in that the separator 26 is a matte   micro-fibers of woven ndn.   11 - Advanced electrochemical accumulator according to   any one of the preceding claims characterized   in that the electrodes (23,25), the separator (26) and the inhibitor   short circuit (22) are spirally wound in a wound arrangement (2Q).   12 - Electrochemical accumulator according to the claim   1, characterized in that the electrolyte is constituted   by an aqueous solution of sulfuric acid.   13 - Electrochemical accumulator according to the claim   1, characterized in that each of the short-term inhibitors   circuit (2.2) has a greater length than the   electrodes (23,25) and separators (26) so as to create a prolongation   27 on each of the short-circuit inhibitors for   facilitate the winding of the electrode assembly.   14 - Electrochemical accumulator according to the claim   1, characterized in that the housing (15) comprises an element   interior 12 formed of an electrically non-conductive material and an outer member 11 formed of a material   the outer element enclosing the element laughing.   - Method of manufacturing an electronic accumulator   chemical electrode comprising negative electrodes 23 and positive 25 and a separator 26 placed between them intended to isolate the electrodes from each other, characterized in that it comprises the steps of: setting up a short-term inhibitor; porous circuit 22 between the negative electrode 23 and the separator 26 and contiguously thereto, the short-circuit inhibitor 22 being constituted by a fine-meshed material formed   of a polymer fiber resistant to oxidation and   of; placing the electrodes 23, 25, the separator 26, and the short-circuit inhibitor 22 in a housing 15, the housing comprising external terminals 14, 16, each connected to one of the electrodes; addition of an electrolyte in the housing so   the electrolyte comes into contact with the electro-   des, the separator, and the short-circuit inhibitor and, sealing the housing.   16 - Process according to claim 15 characterized in that the short-circuit inhibitor is polyester.   17 - Process according to claim 15 or 16 characters   in that the electrolyte is added to the pressure vessel.   18 - Process according to claim 15 or 16 or 17   characterized in that it comprises the step of winding the electrodes (23, 25), the separator (26) and the inhibitor (22) in a wound arrangement (20) before the step of placing the electrodes, separator, and inhibitor short circuit in the housing.   19 - Process according to claim 18, characterized in that each of the short-circuit inhibitors (22) has a length greater than that of the electrodes (23, 25) and the separator (26) so as to create an extension 27 on each short-circuit inhibitor and in that the step of winding the electrodes, the separator of the inhibitors   of a short-circuit in a wound-up arrangement (20) comprises the step -   application of a retractor device to the extensions   short circuit inhibitors so that the   tensity of the tensile forces used in the step   winding is supported by short-term inhibitors circuit (22).