JPH01500546A - Nickel-hydrogen battery with internal short-circuit device in case of failure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Notsuru Karu A 戟itch 瀉 I winter J 佳薴 iro nizode tb --KX! b Background of the invention The present invention relates to batteries, particularly pressurized nickel-metal hydride batteries.

A rechargeable cell or battery is an electrochemical device that stores and retains an electric charge. , discharging this charge as a useful current. Examples of rechargeable batteries include automobile There are lead-acid batteries used in A battery with a large charging capacity compared to its weight has a pressurized gas-metal battery, an important type of battery used in spacecraft. There are nickel-metal hydride batteries used.

The nickel-metal hydride batteries inside the satellite are powered by electrical current generated by the spacecraft's solar cells. It is charged automatically and released when the spacecraft enters shadow or when large amounts of power are needed. powered and provides power. A single cell of a nickel-metal hydride battery discharges at approximately 1.3 volts. Usually, a large number of batteries are connected in series to provide the required voltage and current for the systems inside the spacecraft. supply.

Nickel-metal hydride batteries are batteries that electrochemically store electrical charge and discharge it as a useful current. It has a continuous set of active plates and is held within a pressure vessel. Furthermore, inside this pressure vessel, The electrolyte plate set and the hydrogen and oxygen gases and water vapor formed during battery operation. The battery is sealed, and if these gases and water vapor leak, the battery will become inoperable.

Pressurized gas storage batteries usually have a high degree of stability and can be used inside satellites or other spacecraft. It can be charged and discharged several thousand times over its normal lifespan. However, this battery If there is a hole in the pressure vessel, the liquid and gas inside may leak and cause a malfunction. There is a potential. If such a battery open circuit occurs, the battery will fail. this is This is because the current path in the battery is only through the electrolyte, and this electrolyte is gradually lost. be. Normally, a large number of single cells are connected in series, and the current flows at a given voltage as a battery. supply. Therefore, if any of the single cells fails due to an open circuit, this Since there is no circuit to bypass a failed single cell, the operation of the entire battery is at risk. Become.

It is possible that a single cell failure could render the entire battery inoperable, and cannot be repaired, so batteries used in space require a A fault protection circuit device is installed that detects a fault and creates a current path around the faulty cell. It is normal to If a fault occurs, this fault protection circuit device is The single cell is isolated and current is conducted around the failed single cell. battery out The power voltage will drop by the voltage of the failed single cell, but the battery usually has sufficient margin. Even if a certain number of single cells fail, the voltage required by the spacecraft will be maintained. It does not cause any deterioration.

A fault protection circuit device is installed inside or outside the battery and includes a diode network. A single cell failure is detected by a circuit or relay, and a circuit is installed around the failed single cell. Reshape. The weight of these electrical components and associated circuitry add to the weight of the battery. significantly increases and reduces the spacecraft's available payload.

Additionally, if any component of the fault protection circuit device fails, the battery and the entire spacecraft will be damaged. becomes dangerous.

Therefore, there is a need to eliminate such single cell failures of batteries. This person According to the law, it should not be an external circuit, should not be heavier than a failure protection circuit device, and should be a battery-powered device. It is necessary to ensure that the system operates reliably for a long period of time. Furthermore, modern batteries are not reliable. Because it is highly reliable, it must be compatible with conventional ones. This invention is this It satisfies these requirements and provides further advantages.

Summary of the invention Due to its internal structure, the nickel-metal hydride battery according to the present invention has a short circuit when it fails. state, and does not require an external failure protection circuit device. Therefore, the battery Even if a single cell fails, it does not cause a failure of the entire battery, but simply the output of the failed single cell. This will only reduce the power and voltage properties. The weight of a battery using such a single cell is Largely reduced cell storage component than normal battery with fault protection circuit device does not change.

The nickel-hydrogen battery according to the present invention comprises a nickel positive electrode, a hydrogen negative electrode, and these positive and negative electrodes. An active plate set including a separator disposed between the negative electrode and the negative electrode. teset), and the voltage inside and between this active plate set and the positive and negative electrodes. a pressure vessel containing a solute and an electrical conductor connecting the active plate. (electrical feed throughs), and furthermore, the cell means to short-circuit the current path through this cell when the voltage exceeds a predetermined negative value. The cell is enclosed in a pressure vessel, which causes the cell to become short-circuited if it fails. Furthermore, Ni A Kellu hydrogen battery consists of a nickel positive electrode, a hydrogen negative electrode, and a battery placed between these positive and negative electrodes. An activated plate including a separator!・And the short circuit placed in parallel with this active board set This shorting plate set includes a nickel shorting electrode, a silver soluble electrode, This has a nickel shorting electrode and a shorting separator placed between the silver soluble electrode. , further comprising a pressure vessel containing an active plate set, a short circuit plate cella (.) and an electrolyte, The pressure vessel includes electrical conductors for these plate sets.

A dissolvable electrode (rod) is used in this battery. However, it may be formed of a substance other than silver as long as it has a similar function. material In terms of functionality, nickel-metal hydride batteries have a nickel positive electrode, a hydrogen negative electrode, and An active plate set including a separator between the positive electrode and the negative electrode, and an active plate set parallel to this active plate set. This short-circuit plate set includes a short-circuit electrode, a soluble electrode, and a short-circuit plate set. a shorting electrode and a shorting separator between the soluble electrodes, and the soluble electrode has a maximum negative If the voltage has a high overvoltage with the material of the shorting electrode during normal operation when the voltage is about 0.3 volts, This soluble electrode material is inert in the electrolyte. A short circuit occurs when a negative voltage greater than approximately 1.5 volts is applied to the short circuit plate set. can be deposited on the poles and further contains an active plate set, a shorting plate set and an electrolyte. A pressure vessel is provided which includes electrical conductors to the set of plates. short Preferably, the crossing electrode is nickel. Silver is the material for forming soluble electrodes. Preferably, the soluble electrodes are made of materials such as lead, copper or cadmium. Good too.

During normal battery operation, the voltage ranges from +1.7 volts to -0.3 volts. Due to the presence of overvoltage on the nickel and silver surfaces, there is no A visible current flows. During this normal operation, the battery of the present invention It operates in much the same way as a hydrogen battery. Failures such as holes forming in the pressure vessel occur. In this case, a large negative voltage will be generated on the shorting plate set. This negative voltage is approximately minus 1 ．． Above 5 volts (i.e. in the direction of more negative voltages), the silver electrode becomes oxidized. becomes silver oxide (Ag20), and this silver oxide (silver 1IIonoxide) ) is soluble in electrolytes. Melted silver oxide becomes a short-circuit electrode. It migrates and turns into silver, thereby depositing silver on the shorting electrode. And the short circuit electrode The silver electrodes are completely bridged with silver and short-circuited, and the cell itself is short-circuited. Short circuit plate set Since the cell is placed in parallel with the active plate set, the cell will be shorted due to an internal short circuit. . Therefore, a cell failure according to the invention forms a short or short circuit; Current flows through this failed cell. A failed cell produces no voltage, but The output voltage of the entire battery with these cells connected in series is only the voltage of the failed cell. descend. External fault protection circuit equipment is not required to create a short circuit in the event of a fault. stomach.

Therefore, according to the present invention, a spacecraft battery cannot fail due to an open circuit in a single cell. prevents complete battery failure without the need for heavy fault protection circuitry. will be stopped. When a single cell fails, the short-circuit plate set in this cell will short-circuit. As a result, operation continues at a voltage reduced by the voltage of the failed cell. The present invention Other features and advantages will be apparent from the detailed description below, along with the accompanying drawings that illustrate the principles of the invention. A brief explanation of the drawing that is clearer Figure 1 is a schematic diagram of a lightweight nickel-metal hydride battery with multiple cells connected in series. Elevation, Figure 2 is a cross-sectional elevation view of 1 of the lightweight nickel-metal hydride cell shown in Figure 1; Figure 3 is a detailed explanatory diagram along line 3-3 in Figure 2, showing the active board set and preferred format. shows the structure, arrangement and electrical connection of the shorting plate set, Fig. 4 is a sectional view showing another structure of the shorting plate set, and Fig. 5 is a sectional view showing another structure of the shorting plate set. Figure 6 is a graph of time and voltage during operation of the short circuit plate set. It is.

Description of the preferred embodiment The nickel-metal hydride battery 10 stores excess energy generated by the spacecraft's solar cells. In addition, when the output of the solar cells decreases, the stored energy is supplied to the spacecraft system. do. A battery 10 includes a number of nickel-metal hydride cells 1 as an energy storage unit. Contains 2. Each cell 12 provides stored energy at a voltage of approximately 1.3 volts, This voltage is too low to operate spacecraft systems. Therefore, each cell 12 are connected in series with each other as shown in Figure 1, and the total voltage of each cell 12 is the battery voltage. form a voltage. In the embodiment of FIG. 1, five cells 12 each have a voltage of 1.3 volts. five cells connected in series have an output voltage of to supply current at 6.5 volts. 1 cell if no fault protection device is installed 12 fails, the battery 10 becomes an open circuit and cannot supply current. stomach. Conventional external fault protection devices fail as shown schematically by the dotted line 14. Form an external line that detours around the cell. In the present invention, as shown diagrammatically by dotted lines, The conductor 16 passing through the failed cell forms an internal track, which connects the battery 1. 0 is the voltage that has dropped to 5.2 volts in the example of Figure 1, and the remaining cells continue to operate. Let's go. According to this, it is possible to eliminate the conventional heavy burden required to form the external line 14. A fault protection circuit device is not required.

FIG. 2 shows the nickel-metal hydride cell 12 and its constituent parts.

The cell 12 comprises a number of independent active plate sets 18 connected in parallel. Details are shown in FIG. Each active plate set 18 has an anode or a negative electrode 20 , a cathode or negative electrode 22, and a separator 24 containing an electrolyte. , this separator physically separates the electrodes 20.22 and also transports ions and electrons. supply a moving electrolyte medium. Charging and discharging of the electrodes 20° and 22 are performed using two sets of lead wires 2. 6.

All the positive electrodes 20 are connected in parallel to one set of leads 26 and the negative electrodes 22 are all connected in parallel to the other lead wire set 26.

Various structures and constituent parts of nickel-metal hydride batteries are known. U.S. Patent Nos. 4,389,212 and 4,283,844 , No. 4,262.061, No. 4.250,235, No. 4.000,350 and 3rd. There is Ei69.744.

The positive electrode 20 is made by impregnating porous fired nickel with nickel hydroxide. Formed by supporting nickel with an etched nickel electrode base material. It is preferable to

The negative T electrode 22 is made of a fired mixture of platinum black and polytetrafluoroethylene on the negative side. The other side is covered with a porous polytetrafluoroethylene layer. this These layers are applied to an etched sheet or knitted nickel substrate. is formed into a negative electrode 22, which is called a hydrogen electrode. The separator 24 has various shapes. Formulas can be used, such as asbestos, nylon and zirconium oxide. zironiuIloxide-yttrlumu oxi de) It is cloth. The electrolyte is a potassium hydroxide aqueous solution, especially a 31% aqueous solution, separated into Preferably, it is included within the electrode 24 and between and within the electrode spaces.

Each active plate set 18 has a laminate (siaeked a) arranged with a central core 28. rray) 30. When forming this laminate 30, single fiber polyester Propylene screen (IIlonofilaa+ent polypropy len 5 screen) 32 is placed between each active plate set 18, and each positive electrode 20 Oxygen released during overcharging is spread from this electrode 20 toward the negative electrode 22. dispersed and combined with hydrogen. The laminate 30 has a bonding press plate 34 that abuts each end. For example, IO bond per square inch (about 0.7 kg/ca in the longitudinal direction) Under pressure. Tightening of the pressing plate 34 presses the laminate 30 and tightens the core 28. Tighten the nut 36 on the screw, thereby pressing the disc spring set 38 against the pressing plate 34. , it is preferable to hold the stack 30 in a predetermined position.

The laminate 30 is sealed within a pressure vessel 40, which may be, for example, an in-connector. 718 nickel-based alloy, which is susceptible to damage due to hydrogen embrittlement. Absolute pressure 1.000 psl (approximately 700 kg/c- d) can withstand internal pressures of the order of magnitude. The gas supply tube 42 allows pressure The amount and pressure of gas inside the container can be controlled. This pressure vessel 40 usually has a spherical end. It is formed into a cylindrical tube with. Pressure in the illustrated cell or battery 12 The container has an outer diameter of 31/2 inches (approximately 8.9 cm) and a length of 13 inches (approximately 33 cm). ), has a set of about 40 active plates 18, and has a voltage of about 1.3 volts. 50AH electrical storage capacity ). This battery is acceptable if charged and discharged properly. They typically have a charge/discharge cycle life of several thousand cycles without significant damage. child A large number of these batteries 12 are connected in series to form a high voltage as shown in FIG. Alternatively, they can be connected in parallel to form a battery capable of supplying high current.

When a voltage is applied to each active plate set 18 via the lead wire 26, electrons are transferred to the electrode 22. It flows from the battery to the electrode 20 and is charged. This causes each activated plate set 18 to undergo a chemical reaction. Electrical energy is stored and forms a useful current when discharged. 2 of the above format Kkeru hydrogen batteries can be fully charged by solar arrays, and their capacity is as follows: For example, it can be charged from a discharged state for about 14 hours at a current of about 1.5 volts and 5 amperes. It has a capacity of 50 ampere-hours. This voltage and charging time It can vary over a wide range depending on the power of the battery array and the orbit of the spacecraft.

According to the present invention, battery 12 is activated when the cell voltage exceeds approximately minus 1.5 volts. (i.e. more negative than -1.5 volts), short this cell. It includes a means to do so.

In a preferred embodiment, this means includes a short circuit juxtaposed to the active plate set 18 within the battery 12. A preferred embodiment of a bridging plate set 50 is shown in FIG. This shorting plate Set 50 includes a shorting electrode 52, a dissolvable electrode 54, and an electrode support 56; A soluble electrode 54 is supported on this electrode support, and a short-circuit separator 58 is a short-circuit electrode. and the soluble electrode 54.

This shorting plate set 50 is electrically parallel to the active plate set 18 via the lead wire 26. As shown in FIG. It is advantageous in that it is attached to 28. The shorting electrode 52 is connected to the positive electrode 20, Soluble electrode 54 is connected to negative electrode 22 . The shorting electrode 52 is a nickel plate. The soluble electrode 54 is a fired silver plate or sheet, and the short-circuit separator 58 is a sheet. Made of improved zirconia cloth (a+odiried zirconia cloth) It is preferable to form each.

During normal operation of the cell 12, the shorting plate A negligibly small current flows through the set 50. Hydrogen was released due to damage to the pressure vessel. , if a cell 12 failure occurs such that electrolyte leaks and an open circuit occurs, the negative A negative voltage greater than 1.5 volts is created across cell 12.

The soluble electrode 54 is oxidized and becomes soluble in the electrolyte. There is a silver plate with a soluble electrode In the preferred embodiment, the silver is silver oxide (S ver. a+). onoxlde), complexed and dissolved in potassium hydroxide electrolyte. Ru. This dissolved silver oxide is deposited on the nickel electrode 52. coated. The coated silver increases in thickness during repeated charging and discharging of the cell 10, and the final is thick enough to bridge the electrodes 52.54 between the electrodes 52.54. 54 to form a current path or short circuit path. Therefore, negative high voltage A cell failure resulting in a cell failure would result in a direct internal short between electrodes 52,54. cell Instead of a failure resulting in an open circuit, it results in a short circuit, meaning that the failed cell The underlying battery can continue to operate at reduced voltage.

FIG. 4 shows another embodiment of the shorting plate set 50. The structure of this board set is shown in Figure 3. Similar to the shorting plate set, except that the nickel screen 60 is connected to the shorting separator 58. The difference is that it is inserted between the short-circuiting electrode 52 and the short-circuiting electrode 52. Silver is deposited on the shorting electrode 52. , when the formation of a bridge shorting the plate set 50 begins, the required heat is generated, and this heat The disc spring 38 presses the remaining part of the dissolvable electrode 54 toward the shorting electrode 52, and the Ni Destroy Kelscreen 60. This accelerates the shorting process.

FIG. 5 shows yet another embodiment of the shorting plate set 50. This structure is shown in Figure 3. Almost similar to the board set, but the electrode plate 56 supports the dissolvable electrode 54 and The purpose is to maintain electrical contact and does not serve any absolutely necessary function. stomach. As long as the soluble electrode 54 has sufficient rigidity and can make reliable electrical contact with it. For example, the electrode support 56 can be omitted as in the embodiment shown in FIG. But dissolved The use of the sexual electrode support 54 increases reliability and its flfjl also increases slightly. It is preferable to use this support because only

The shorting electrode 52 is made of nickel because it is compatible with the positive electrode 20 of the active plate set 18. is preferred. Dissolvable electrode 54 is preferably made of silver; other materials include lead, copper, and cadmium. Mium can also be used. These materials in a 31% potassium hydroxide solution The oxidation potential is -0.35 volts for silver, 0.36 volts for copper, and 0 for lead. ．． 58 volts, cadmium is 0.81 volts. The negative oxidation potential is the most Silver, which is an expensive material, is preferred.

The following examples are illustrative and do not limit the invention.

Example 1 The preferred type of shorting plate set shown in FIG. Tests were conducted using a silver soluble electrode that acted as a positive electrode in case of failure. Table below I summarizes the test results.

Table I current Time interval Silver state Voltage (milliampere) Initial 1.30 8 - 1.91 19 -2.54 2250 -1.58 1 Retrograde + -0,440 + −0,661 + −1,5018 + -2,582781 10-3,0310110 The shorting plate set is lower than +1.7 volts and lower than -0.3 volts. When operated in the normal range with little negative current, almost no current flowed. Se If the voltage increases above approximately minus 1.5 volts (i.e., (more negative than -1.5 volts), more current flows and the silver electrode melts. solution and the same structure used in Example 1, with nickel deposited on the electrode and shorting the cell. Connect the silver electrode corresponding to the faulty cell as the positive electrode to a short-circuit plate set made of A current was passed continuously. The time and cell voltage results are shown in Table H below. .

Table■ 0.6 2.9 0.8B 2.7 0.88 2. Ei 3 0.88 12 0.59 26 0.57 67 0.53 123 0.50 189 0.49 251 0.48 397 0.43 The band graph recorder that recorded the voltage was able to record the transients It showed a continuous downward trend without any lag. This is a form of short circuit through the plate set This shows that the formation occurs slowly and continuously in the desired manner.

Example 3 A shorting plate set of the type used in Example 1 was operated under normal charging and discharging conditions. . This state is shown in FIG. A large negative voltage is applied to the short circuit plate set according to the nature. The voltage was applied to create a short-circuit condition, and the silver-soluble electrode was used as the positive electrode. Negative voltage increases , the shorting plate set functions in the desired manner to short circuit and create a low voltage across the plate set. .

As shown in the above examples, the shorting plate set of the present invention operates in a desirable manner and does not fail. Instead of putting the battery containing the cell in an open circuit, it puts it into a short circuit. External failure insurance No protection circuitry is required, which reduces battery weight while ensuring continuous operation. Do a little. While specific embodiments of the invention have been illustrated and described above, Obviously, various modifications within the scope are possible. Therefore, the present invention does not cover the claimed invention. There are no equivalent limitations except in scope.

FIG, I FIG. 2 international search report ANNEX To THE rNTERNATIONA 5EARCHREP ORT ON

Claims (16)

[Claims] 1. A nickel positive electrode, a hydrogen negative electrode, and a an active plate set having a separator; and a short circuit plate set juxtaposed to the active plate set. This short-circuit plate set includes a short-circuit electrode, a soluble electrode, and a short-circuit electrode. a short circuit separator disposed between the electrode and the soluble electrode, the soluble electrode comprising: During normal operation, where the maximum negative voltage is about 0.3 volts, the shorting electrode material and This is made of materials that have a high overvoltage in combination and are insoluble in the electrolyte. The soluble electrode material has a voltage higher than about -1.5 volts on the shorting plate set. When negative voltage is applied, it can be dissolved in the electrolyte and deposited on the shorted electrode. , further comprising a pressure vessel containing the active plate set, the short circuit plate set, and the electrolyte. nickel, the pressure vessel comprising an electrical conductor of said set of plates. -Hydrogen battery. 2. The soluble electrode is selected from the group consisting of silver, lead, copper and cadmium. 2. A battery according to claim 1, wherein the battery is made of a material made of 3. 2. The battery of claim 1, wherein said soluble electrode is formed of silver. 4. 2. The battery of claim 1, wherein said shorting electrode is formed of nickel. 5. 2. The battery of claim 1, wherein the soluble electrode is supported by an electrode support. 6. The shorting plate set includes a screen inserted between the shorting electrode and the shorting separator. 2. The battery according to claim 1, comprising: a battery. 7. The battery according to claim 1, comprising a plurality of said active plate sets. 8. 2. The battery of claim 1, wherein the electrolyte is an aqueous solution of potassium hydroxide. 9. A nickel positive electrode, a hydrogen negative electrode, and a an active plate set having a separator; and a short circuit plate set juxtaposed to the active plate set. This shorting plate set includes a nickel shorting electrode, a silver melting electrode, and a shorting separator disposed between the nickel shorting electrode and the silver soluble electrode; , A pressure vessel having the activation plate set, the short circuit plate set, and an electrolyte is provided. A nickel-metal hydride battery, wherein the pressure vessel includes the electrical conductor of the plate set. . 10. The battery according to claim 9, comprising a plurality of said active plate sets. 11. The battery according to claim 9, wherein the electrolyte is an aqueous solution of potassium hydroxide. . 12. 10. The battery of claim 9, wherein the soluble electrode is supported by an electrode support. . 13. A screen is disposed between the shorting electrode and the shorting separator. The battery according to claim 9. 14. Claim 9, wherein the short circuit separator is made of zirconium oxide. Batteries listed in section. 15. A nickel-metal hydride battery, A nickel positive electrode, a hydrogen negative electrode, and a separator between these positive and negative electrodes. an activated plate set having a pressure regulator; the activated plate set; and an electrolyte; a pressure vessel, the pressure vessel further comprising an electrical conductor coupling the active plate set; To, contained in the pressure vessel, and when the voltage of the battery exceeds a predetermined negative value, the A method of electrochemically shorting the current path through the battery and creating a short-circuit state when the battery fails. A nickel-metal hydride battery characterized by having stages. 16. 16. The battery of claim 15, wherein said means includes a set of shorting plates.