JP7036757B2 - Nickel-metal hydride secondary battery regeneration method and nickel-metal hydride secondary battery regeneration device - Google Patents

Description

The present invention relates to a method for regenerating a nickel-metal hydride secondary battery and a device for regenerating a nickel-metal hydride secondary battery.

The nickel-metal hydride secondary battery is composed of a positive electrode containing nickel hydroxide as a main component, a negative electrode containing a hydrogen storage alloy as a main component, and an alkaline electrolytic solution. Generally, in a nickel-metal hydride secondary battery, the capacity of the negative electrode is larger than the capacity of the positive electrode. As a result, the discharge capacity of the battery is limited by the capacity of the positive electrode (hereinafter, this is referred to as positive electrode regulation). In a normal nickel-hydrogen secondary battery, the rechargeable uncharged portion left on the negative electrode when the positive electrode is fully charged is called a charge reserve, and the chargeable portion left on the negative electrode when there is no charged portion on the positive electrode can be discharged. The charged part is called the discharge reserve. As described above, by setting the positive electrode regulation, it is possible to suppress an increase in internal pressure due to a reaction that occurs during overcharging and overdischarging.

On the other hand, the hydrogen stored in the hydrogen storage alloy may be insufficient. For example, when hydrogen leaks to the outside of the battery case, hydrogen is released from the hydrogen storage alloy in order to maintain the partial pressure of hydrogen in the case, and the discharge reserve of the negative electrode is reduced. If the battery is used for a long period of time and the discharge reserve is significantly reduced, the capacity of the battery may be reduced due to the negative electrode regulation limited by the capacity of the negative electrode. For example, Patent Document 1 describes an example of a technique for adjusting the discharge reserve of a nickel-metal hydride secondary battery.

The technique described in Patent Document 1 overcharges a nickel-hydrogen secondary battery including a positive electrode and a negative electrode, discharges at least a part of oxygen gas generated from the positive electrode to the outside of the nickel-hydrogen secondary battery, and discharges the battery. It is provided with a discharge reserve adjustment step that increases the capacity of the reserve.

Japanese Unexamined Patent Publication No. 2008-23536

In recent years, the charge reserve of a nickel-metal hydride secondary battery may disappear depending on the intended use of the battery. In a Nikke hydrogen secondary battery whose charge reserve has disappeared, the charge capacity of the battery becomes a negative electrode regulation limited by the capacity of the negative electrode whose charge reserve has disappeared, and may be lower than the positive electrode regulation limited by the capacity of the positive electrode. be.

The present invention has been made in view of such circumstances, and an object thereof is a method for regenerating a nickel-metal hydride secondary battery capable of recovering a charge reserve of a nickel-metal hydride secondary battery and a method for regenerating a nickel-metal hydride secondary battery. The purpose is to provide a reproduction device.

A method for regenerating a nickel-hydrogen secondary battery that solves the above problems is a nickel-hydrogen secondary battery having an electrolytic solution consisting of a positive electrode containing an active material containing nickel hydroxide as a main component, a negative electrode containing a hydrogen storage alloy, and an alkaline aqueous solution. This is a method for regenerating a nickel-hydrogen secondary battery, in which hydrogen gas and oxygen gas are generated from a secondary battery whose negative charge reserve has disappeared by overcharging under predetermined conditions, and in the case of the secondary battery. The overcharging step comprises an overcharging step of increasing the internal pressure to the opening pressure of the exhaust valve for discharging the gas in the case and releasing the gas in the case to the outside. In the overcharging step, the overcharging under the predetermined conditions is provided. The gas ratio, which is the ratio of the number of hydrogen molecules (H ₂ ) to the number of oxygen molecules (O ₂ ) generated in, is increased by 2.5 times or more.

A nickel-hydrogen secondary battery regenerator that solves the above problems is a nickel-hydrogen secondary battery having an electrolytic solution consisting of a positive electrode containing an active material containing nickel hydroxide as a main component, a negative electrode containing a hydrogen storage alloy, and an alkaline aqueous solution. This is a regenerating device for a nickel-hydrogen secondary battery that regenerates hydrogen gas and oxygen gas in the secondary battery in which the charge reserve of the negative electrode has disappeared by overcharging under predetermined conditions. The battery case is provided with an overcharging unit that raises the internal pressure of the battery case to the valve opening pressure of the exhaust valve that discharges the gas in the case and releases the gas in the case to the outside, and the overcharging unit is provided with the predetermined conditions. The gas ratio, which is the ratio of the number of hydrogen molecules (H ₂ ) to the number of oxygen molecules (O ₂ ) generated by the overcharging, is increased by 2.5 times or more.

Normally, a nickel-metal hydride secondary battery is generated at a gas ratio in which the number of hydrogen molecules is doubled with respect to the number of oxygen molecules due to overcharging.
In this regard, according to such a method or configuration, the gas ratio, which is the ratio of hydrogen gas to oxygen gas generated by overcurrent, becomes 2.5 times or more, which is higher than twice the normal gas ratio. The discharge of gas having a high gas ratio increases the discharge of hydrogen gas to the outside of the case. The decrease in hydrogen gas in the case increases the charge reserve of the negative electrode by releasing hydrogen from the hydrogen storage alloy in order to maintain the partial pressure of hydrogen in the case. As a result, the charge reserve of the nickel-metal hydride secondary battery can be restored.

As a preferred method, the predetermined condition comprises at least one of a charging current and a battery temperature.
According to such a method, an appropriate gas ratio can be obtained by adjusting the charging current and the environmental temperature included in the predetermined conditions.

As a preferred method, the gas ratio is 3.5 times or more.
According to such a method, more hydrogen gas can be discharged outside the case to restore the charge reserve.

As a preferred method, when the value of the gas ratio is a predetermined ratio, the relational expression of the predetermined ratio = 2.601-0.048 × charging current [C] + 0.037 × battery temperature [° C.] is satisfied. A setting step for setting the charging current and the battery temperature is provided.

According to such a method, the charging current, the environmental temperature and a predetermined ratio can be set to appropriate values for the regeneration process.
As a preferred method, the charging current is 0.5 C or less.

According to such a method, the ratio of hydrogen gas contained in the gas generated by overcharging can be increased by setting the charging current to 0.5 C or less, which is 0.5 times the rated current.
As a preferred method, the battery temperature is 50 ° C. or higher.

According to such a method, the ratio of hydrogen gas contained in the gas generated by overcharging can be increased by setting the battery temperature to 50 ° C. or higher.

According to the present invention, the charge reserve of the nickel-metal hydride secondary battery can be restored.

FIG. 3 is a cross-sectional view showing a front cross-sectional structure of a rechargeable nickel-metal hydride secondary battery in an embodiment of a method for regenerating a nickel-metal hydride secondary battery and a rechargeable device for a nickel-metal hydride secondary battery. It is a conceptual diagram which shows the balance between the positive electrode capacity and the negative electrode capacity of the said nickel-metal hydride secondary battery, (a) is a figure which shows the state of a positive electrode regulation, (b) is a figure which shows the state of a negative electrode regulation by charging, (c). ) Is a diagram showing a state in which the negative electrode regulation for charging is lifted and the battery is regenerated. It is a schematic diagram schematically showing the amount of gas generated when the nickel-metal hydride secondary battery is overcharged, in which (a) is a diagram when the battery temperature is high and the battery is overcharged with a small current, and (b) is a diagram. The figure when the battery temperature is low or overcharged with a large current. The figure which shows the relationship between the battery temperature and the H ₂ / O ₂ ratio at the time of overcharging the above-mentioned nickel hydrogen secondary battery. The figure which shows the relationship between the current value and H2 / _O2 ratio at the time of overcharging the above-mentioned nickel hydrogen _secondary battery. In the same embodiment, a map for selecting an appropriate H ₂ / O ₂ ratio from the current value and the battery temperature. The block diagram which shows the structure of the reproduction apparatus in the same embodiment. In the same embodiment, the flowchart which shows the procedure of the reproduction method.

A method for regenerating a nickel-metal hydride secondary battery and a regenerating device for the nickel-metal hydride secondary battery will be described with reference to FIGS. 1 to 8.
As shown in FIG. 1, the nickel-metal hydride secondary battery is a closed-type battery, which is a battery used as a power source for vehicles such as electric vehicles and hybrid vehicles. As a nickel-metal hydride secondary battery mounted on a vehicle, a square sealed secondary battery composed of a battery module 90 configured by electrically connecting a plurality of cell units 110 in series in order to obtain a required power capacity is used. Are known.

The battery module 90 has a rectangular parallelepiped square case 300 composed of an integrated battery 100 capable of accommodating a plurality of cells 110 and a lid 200 for sealing the same battery 100. As the square case 300, a resin case can be used. A plurality of irregularities (not shown) are formed on the surface of the square case 300 in order to improve heat dissipation when the battery is used.

The integrated electric tank 100 constituting the square case 300 is made of a synthetic resin material having resistance to an alkaline electrolytic solution, for example, polypropylene or polyethylene. A partition wall 120 for partitioning a plurality of cell cells 110 is formed inside the integrated battery tank 100, and the portion partitioned by the partition wall 120 becomes the battery battery 130 for each cell cell 110. The integrated electric tank 100 has, for example, six electric tanks 130, and FIG. 1 shows four of the six electric tanks 130.

In the electric tank 130 partitioned in this way, the electrode plate group 140, the positive electrode current collector plate 150 and the negative electrode current collector plate 160 joined to both sides thereof are housed together with the electrolytic solution.
The electrode plate group 140 is configured by laminating a rectangular positive electrode plate 141 and a negative electrode plate 142 via a separator 143. At this time, the direction in which the positive electrode plate 141, the negative electrode plate 142, and the separator 143 are laminated (the direction perpendicular to the paper surface) is the stacking direction. The positive electrode plate 141 and the negative electrode plate 142 of the electrode plate group 140 are projected to the side portions opposite to each other in the direction of the plate surface (direction along the paper surface), so that the lead portion 141a and the negative electrode plate 142 of the positive electrode plate 141 are projected. Lead portion 142a is configured. Current collector plates 150 and 160 are joined to the side edge edges of the lead portions 141a and 142a, respectively.

Further, a through hole 170 used for connecting each electric tank 130 is formed in the upper part of the partition wall 120. In the through hole 170, two connection protrusions 151 and 161 of a connection protrusion 151 projecting from the upper part of the current collector plate 150 and a connection protrusion 161 projecting from the upper part of the current collector plate 160 are connected to each other. By welding and connecting through the through hole 170, the electrode plate group 140 of the adjacent electric tanks 130 are electrically connected in series. Of the through holes 170, the through holes 170 located on the outer sides of the electric tanks 130 at both ends are equipped with the positive electrode connection terminal 152 or the negative electrode connection terminal 153 (see FIG. 7) above the end side wall of the integrated electric tank 100. To. The connection terminal 152 of the positive electrode is welded and connected to the connection protrusion 151 of the current collector plate 150. The connection terminal 153 of the negative electrode (see FIG. 7) is welded and connected to the connection protrusion 161 of the current collector plate 160. The electrode plate group 140 connected in series in this way, that is, the total output of the plurality of cell cells 110 is taken out from the positive electrode connection terminal 152 and the negative electrode connection terminal 153 (see FIG. 7).

On the other hand, in the lid body 200 constituting the square case 300, an exhaust valve 210 for making the internal pressure of the square case 300 equal to or lower than the valve opening pressure, and a sensor mounting hole for mounting a sensor for detecting the temperature of the electrode plate group 140. 220 is provided. The sensor mounting hole 220 makes it possible to measure the temperature of the electrode plate group 140 by a hole extending in the electric tank 130 to the vicinity of the electrode plate group 140.

The exhaust valve 210 is for maintaining the internal pressure in the integrated electric tank 100 below an acceptable threshold value, and when the value of the internal pressure exceeds the allowable threshold value and becomes equal to or higher than the valve opening pressure. By opening the valve, the gas generated inside the integrated electric tank 100 is discharged. The internal pressure of the integrated electric tank 100 is made uniform in all the electric tanks 130 by communication holes (not shown) formed in the partition wall 120. As a result, the integrated electric tank 100 discharges gas until the internal pressure equalized in all the electric tanks 130 becomes less than the valve opening pressure, and the internal pressure is maintained below the allowable valve opening pressure. It will be like.

(Composition of electrode plate group)
The positive electrode plate 141 is composed of nickel hydroxide and cobalt as active substances. Specifically, to nickel hydroxide, add an appropriate amount of a conductive agent such as cobalt hydroxide or metallic cobalt powder, and if necessary, a thickener such as carboxymethyl cellulose or a binder such as polytetrafluoroethylene to form a paste. Process. Then, the paste-like processed product is applied or filled in a core material such as a three-dimensional porous body of expanded nickel, and then dried, rolled, and cut to form a plate-shaped positive electrode plate 141. As the nickel foamed three-dimensional porous body, a urethane foamed urethane skeleton whose surface is nickel-plated and then burned down is used.

The negative electrode plate 142 is composed of a hydrogen storage alloy containing mischmetal, nickel, aluminum, cobalt and manganese, which are a mixture of rare earth elements such as lanthanum, cerium and neodymium, as active materials. For details, add a conductive agent such as carbon black to this hydrogen storage alloy, and if necessary, a thickener such as carboxymethyl cellulose and a binder such as a styrene-butadiene copolymer to form a paste. Process. Then, the hydrogen storage alloy thus processed into a paste is applied or filled in a core material such as a punching metal (active material support), and then dried, rolled, and cut to obtain a plate-shaped negative electrode plate 142. To form.

As the separator 143, a non-woven fabric of an olefin resin such as polypropylene, or, if necessary, a non-woven fabric obtained by subjecting the separator to a hydrophilic treatment such as sulfonization can be used.
The positive electrode plate 141, the negative electrode plate 142, and the separator 143 are formed by alternately laminating the positive electrode plate 141 and the negative electrode plate 142 on opposite sides of each other via the separator 143 to form a rectangular parallelepiped group of electrode plates 140. Configure. Then, the outer edge of the lead portion 141a of each positive electrode plate 141 projecting and laminated on one side and the current collector plate 150 are joined by spot welding or the like, and the lead portion 142a of each negative electrode plate 142 projecting and laminated on the other side is joined. The outer edge of the current collector plate 160 and the current collector plate 160 are joined by spot welding or the like.

The welded electrode plate group 140 of the current collector plates 150 and 160 is housed in each electric tank 130 in the square case 300, and the positive electrode current collector plate 150 and the negative electrode current collector plate 160 of the adjacent electrode plate group 140 are housed in each electric tank 130. The electrode plates 140 adjacent to each other are electrically connected in series by being connected by spot welding or the like between the connecting protrusions 151 and 161 projecting above them.

A predetermined amount of an alkaline aqueous solution (electrolyte solution) containing potassium hydroxide as a main component is injected into each battery 130, and the lid 200 seals the opening of the integrated battery 100 to form a plurality of batteries. A battery module 90 having a rated capacity of "6.5 Ah", for example, is composed of a single battery 110 (nickel-metal hydride secondary battery).

(Recovery of charge reserve due to overcharging)
In the charging reaction at the positive electrode and the negative electrode of this nickel hydrogen secondary battery, the reaction of the active material is as shown in the following half-reaction formulas (1) and (3), and the electrolysis of water is the following half-reaction formula (2). , (4). At the time of discharge, the reaction proceeds in the opposite direction. At the negative electrode, the hydrogen storage alloy is hydrogenated during charging, and the hydrogen storage alloy is dehydrogenated during discharging.

(Positive electrode)
Ni (OH ⁾ ₂ + OH- → NiOOH + H ₂ O + e-... ⁽ 1)
OH ^－ → 1 / 4O ₂ + 1 / 2H ₂ O + e ^－ … (2)
(Negative electrode)
M + H ₂ O + e- → MH + OH -... ⁽ 3 ⁾
H ₂ O + e- → 1/2 H ₂ + OH -... ⁽ 4 ⁾
When the half-reaction formulas (2) and (4) are combined, as shown in the reaction formula (5) below, oxygen gas (oxygen molecule: O ₂ ) and hydrogen gas (hydrogen molecule: H ₂ ) are generated by electrolysis of water. Is the reaction that occurs. At this time, the gas ratio, which is the ratio of oxygen gas and hydrogen gas (H ₂ / O ₂ ratio), is “2”.

2H ₂ O → 2H ₂ + O ₂ ... (5)
In the present embodiment, the gas ratio of the generated gas is made larger than "2", and the generated gas is discharged from the electric tank 130 to reduce the hydrogen in the nickel hydrogen secondary battery. When hydrogen is depleted from the nickel-metal hydride secondary battery, hydrogen is discharged from the hydrogen storage alloy of the negative electrode according to the amount of hydrogen depletion in order to maintain the equilibrium of the hydrogen partial pressure in the electric tank 130. From these facts, the inventors of the nickel-metal hydride secondary battery utilize the behavior that the discharge reserve of the negative electrode decreases while the charge reserve of the negative electrode increases, and the charge reserve disappeared at the negative electrode. I found that I could recover.

An example of the charge capacity of a nickel-metal hydride secondary battery will be described.
In the cell 110 shown in FIG. 2A, the negative electrode capacity is larger than the positive electrode capacity, and the charge capacity is regulated by the positive electrode capacity P21. Further, in the initial state at the time of shipment or the like, the negative electrode capacity M21 includes a charge reserve R2 which is the remaining charge capacity when the positive electrode is fully charged L1 and a capacity L0 where the SOC of the positive electrode reaches 0%. The discharge reserve R1, which is the remaining discharge capacity of the above, is secured. Further, in the initial state, the positive electrode capacity P21 and the negative electrode capacity M21 of each cell 110 are in a well-balanced state. The term "fully charged" of the positive electrode as used herein means a state in which the uncharged portion of the positive electrode active material has disappeared in the cell 110 (fully charged L1). At this time, the SOC of the positive electrode is 100%. Further, the state where the SOC of the positive electrode reaches 0%, that is, the state where the charged portion of the positive electrode active material is exhausted (capacity L0) is set to the state where the SOC of the cell 110 is 0%, and the SOC of the positive electrode becomes 100%. The reached state is defined as a state in which the SOC of the cell 110 is 100%. By providing the charge reserve R2 in the negative electrode capacity M21 in this way, it is possible to suppress the generation of hydrogen from the negative electrode during overcharging. Further, by providing the discharge reserve R1 in the negative electrode capacity M21, it is possible to suppress the generation of oxygen from the negative electrode at the time of over-discharge.

In FIG. 2B, the charge reserve R2 of the negative electrode disappears in the relative relationship between the positive electrode capacity P21 and the negative electrode capacity M21 of the cell 110 depending on the intended use, and the fully charged L1 which is 100% of the SOC of the positive electrode is set to 100 of the negative electrode. % May fall below the value of the negative charge reserve R3. At this time, even if the SOC of the positive electrode is less than 100%, the cell 110 cannot be charged because the SOC of the negative electrode becomes 100%, so that charging is restricted to the negative electrode. Therefore, the charge capacity of the cell 110 is regulated by the positive electrode (capacity L0) when discharged, and regulated by the negative electrode (full charge L1-minus charge reserve R3) when charged, which is smaller than that when the positive electrode is regulated. At this time, the negative electrode is in a state in which the negative electrode capacity M21 is shifted to the discharge side, that is, the discharge reserve R1 is in a state in which the charge reserve R2 and the negative charge reserve R3 that have disappeared from the charge side are increased. Therefore, by shifting the negative electrode capacity M21 to the charging side, the charging capacity of the cell 110 can be returned to the positive electrode regulation.

As shown in FIG. 2C, if the negative charge reserve R3 of the cell 110 whose charging is restricted to the negative electrode disappears, the charge capacity of the cell 110 can be set to the state of the positive electrode regulation. That is, by matching the SOC 100% of the negative electrode capacity M21 with the SOC 100% (fully charged L1) of the positive electrode capacity P21, the charge capacity of the cell 110 is regulated by the positive electrode from SOC 0% to 100% of the positive electrode. It can be restored to a state.

By overcharging the cell 110 under predetermined conditions, the negative charge reserve R3 is extinguished.
(Ratio of oxygen gas and hydrogen gas generated by overcharging)
With reference to FIGS. 3 to 6, overcharging under predetermined conditions for extinguishing the negative charge reserve R3 will be described.

FIG. 3 shows a state in which the SOC 100% of the negative electrode capacity M21 is lower than the SOC 100% of the positive electrode capacity P21.
First, as shown in FIG. 3B, a case where the conventional overcharge is performed will be described. When the battery temperature, which is within the conventional guaranteed operating temperature range, is low, or when charging is performed with a large current for the purpose of charging in a short time, the overcharged cell 110 produces oxygen generated at the positive electrode. It is known that the ratio of the amount of gas 31B and the amount of hydrogen gas generated in the negative electrode 32B is larger than twice the value shown in the reaction formula (5) and less than 2.5 times. It should be noted that in FIG. 3, the magnitude of the amount of oxygen gas 31B and the magnitude of the amount of hydrogen gas 32B are similar, indicating that they are well-balanced. At this time, it is also known that the electrolytic solution decreases with overcharging.

On the other hand, as shown in FIG. 3A, overcharging for reproduction in the present embodiment will be described. When the battery temperature is higher than the guaranteed operating temperature range, or when charging is performed with a small current that is not selected for charging purposes, the overcharged cell 110 has an amount of oxygen gas 31A generated at the positive electrode and a negative electrode. It was found that the ratio of the amount of hydrogen gas generated in the above to 32A is 2.5 times or more, which is far from the value shown in the reaction formula (5). It was also found that the decrease in the electrolytic solution due to overcharging was small at this time.

The reason why the ratio of the amount of oxygen gas 31A to the amount of hydrogen gas 32A is 2.5 times or more at least at the time of high temperature and low current is presumed as follows.
Reasons for high temperature:
-As the hydrogen equilibrium pressure rises, hydrogen gas is likely to be generated from the negative electrode in the overcharged region.

-The endothermic reaction of oxygen gas to the negative electrode, which is a reaction occurring other than the above reaction formulas (1) to (4), is promoted at a high temperature.
Reasons due to the small current:
-The reaction of the reaction formula (2) (a side reaction of the positive electrode) is suppressed.

FIG. 4 is a diagram showing the ratio (gas ratio) of the gas generated when the cell 110 having the negative charge reserve R3 in the negative electrode to the oxygen gas and the hydrogen gas in relation to the battery temperature. For example, here, the negative charge reserve R3 is "-1.35 Ah".

As shown in the graphs L41 and L42, the gas ratio is low when the battery temperature is relatively low and high when the battery temperature is relatively high. That is, as the temperature rises, the proportion of hydrogen gas in the gas generated in the cell 110 increases. Therefore, the gas ratio becomes large when the battery temperature is high.

As shown in the graphs L41 and L42, it can be seen that the gas ratio is higher when the charging current is 2A (0.3C) than when the charging current is 158A (24.3C). From these facts, in order to raise the gas ratio, it is preferable to raise the battery temperature and reduce the charging current value.

For example, when a very suitable gas ratio is 3.5 or more, the battery temperature is preferably 30 [° C.], more preferably 40 [° C.], and even more preferably 50 [° C.], because a higher battery temperature is preferable. ..

FIG. 5 is a diagram showing the gas ratio of the gas generated when the cell 110 having the negative charge reserve R3 on the negative electrode is overcharged in relation to the charging current value. For example, here, the negative charge reserve R3 is "-1.35 Ah".

As shown in the graphs L51 and L52, the gas ratio is low when the current value is relatively large and high when the current value is relatively small. That is, as the current value decreases, the proportion of hydrogen gas in the gas generated in the cell 110 increases. Therefore, the gas ratio becomes large when the charging current value is small.

As shown in the graphs L51 and L52, it can be seen that the gas ratio is higher when the battery temperature is 45 ° C. than when the battery temperature is 25 ° C. From these facts as well, as described above, in order to raise the gas ratio, it is preferable to reduce the current value and raise the battery temperature.

For example, when a very suitable gas ratio is 3.5 or more, the charging current value [C] is preferably 0.5 [C], more preferably 0.3 [C], because it is preferable that the charging current value [C] is small. 0.1 [C] is even more preferable.

(Battery temperature, current value and gas ratio)
FIG. 6 is a map 60 showing the relationship between the battery temperature, the current value, and the gas ratio. Map 60 shows the conditions under which a gas ratio suitable for the disappearance of the negative charge reserve R3 can be obtained. If the gas ratio is 2.0 or less, the negative charge reserve R3 cannot disappear. Therefore, in the map 60, "⊚" is suitable when the gas ratio is 3.5 times or more, which is very suitable, and "○" is suitable when the gas ratio is 3.0 times or more and less than 3.5 times, which is more suitable. When it is 5.5 times or more and less than 3.0 times, it is indicated by "Δ", and when it is less than 2.5 times, which is the same as the conventional one, it is indicated by "x".

More specifically, the relationship between the charging current value [C] and the battery temperature [° C] is "×" and "5 ° C" when the charging current value is "-5 ° C" with respect to "0.1C". When it is "Δ", when it is "15 ° C", it is "○", and when it is "25 ° C, 35 ° C, 45 ° C, 55 ° C and 65 ° C", it is "◎".

Further, for the charging current values of "0.3C and 0.5C", "×" when "-5 ° C", "△" when "5 ° C", "○" when "15 ° C", It is "◎" when it is "25 ° C, 35 ° C, 45 ° C, 55 ° C and 65 ° C".

Further, with respect to the charging current value of "1C", "×" when "-5 ° C", "△" when "5 ° C", "○" when "15 ° C and 25 ° C", and "35 ° C". , 45 ° C, 55 ° C and 65 ° C ”is“ ⊚ ”.

In addition, when the charging current value is "5C", it is "x" when it is "-5 ° C", "△" when it is "5 ° C and 15 ° C", and "○" and "35 ° C" when it is "25 ° C". , 45 ° C, 55 ° C and 65 ° C ”is“ ⊚ ”.

Further, for a charging current value of "10C", "x" when "-5 ° C and 5 ° C", "△" when "15 ° C", and "○" when "25 ° C and 35 ° C". It is "◎" when it is "45 ° C, 55 ° C and 65 ° C".

Further, when the charging current value is "24.3C", it is "x" when it is "-5 ° C, 5 ° C, 15 ° C and 25 ° C", and when it is "35 ° C", it is "△" and "45 ° C". When "○" and "55 ° C and 65 ° C", it is "◎".

That is, in order to recover the charge capacity of the cell 110 having the negative charge reserve R3 in the negative electrode, the value of the charging current value [C] and the value of the battery temperature [° C.] are mapped in order to be very suitable. It is preferable to set the value corresponding to "◎" of 60. Further, in order to make it more suitable, it is preferable to set the value corresponding to "◯" in the map 60, and in order to make it more suitable, it is preferable to set the value corresponding to "Δ" in the map 60.

Further, the inventors have found that the relationship between the battery temperature, the current value and the gas ratio can be shown by the following relational expression (6) from these facts.
Gas ratio (H ₂ / O ₂ ratio) =
2.601-0.048 x charging current [C] + 0.037 x battery temperature [° C] ... (6)
That is, in order to recover the charge capacity of the cell 110 having the negative charge reserve R3 in the negative electrode, the value of the charge current value [C] and the value of the battery temperature [° C.] are used so as to achieve the target gas ratio. Should be determined.

(Regeneration processing of nickel-metal hydride secondary battery)
With reference to FIGS. 7 and 8, a nickel-metal hydride secondary battery regeneration device 1 and a nickel-metal hydride secondary battery regeneration method will be described. Here, a case where the battery module 90 including a plurality of cell cells 110 is regenerated will be described. By considering the entire battery module 90 as the cell 110, the battery module 90 can be regenerated based on the relationship described above. The battery module 90 may be composed of one cell 110.

Further, the reproduction device 1 can be mounted on the vehicle (on-board) and can reproduce the battery module 90 of the vehicle in real time or based on the accumulated data.
As shown in FIG. 7, the nickel-metal hydride secondary battery regeneration device 1 regenerates the charge capacity of the battery module 90 whose charge capacity is regulated by the negative electrode. The reproduction device 1 recovers the charge capacity by extinguishing the negative charge reserve R3 of each cell 110 of the battery module 90.

The reproduction device 1 includes a charging device 20 for charging the battery module 90, a current detector 21 for measuring the current from the charging device 20, a voltage detector 22 for measuring the voltage between terminals of the battery module 90, and a battery module 90. It is provided with a temperature detector 23 for measuring the temperature of the battery module 90 and a temperature adjusting device 24 for adjusting the temperature of the battery module 90. Further, the reproduction device 1 includes a control device 10 that controls charging by the charging device 20.

The charging device 20 is connected between the positive electrode connection terminal 152 and the negative electrode connection terminal 153 of the battery module 90. The charging circuit of the charging device 20 has a charging power source and a switch connected in series to the charging power source, and opens and closes the switch based on an instruction signal from the control device 10. The charging circuit can adjust the amount of charging current to a specified value. In the charging circuit, the electrical connection with the battery module 90 is cut off by opening the switch, while the battery module 90 electrically connected can be charged by closing the switch.

The current detector 21 is connected in series to the battery module 90 and the charging device 20 via the positive side wiring PL and the negative side wiring ML. The current detector 21 measures the current from the charging device 20 and outputs the measured current value to the control device 10 as an electric signal.

The voltage detector 22 is connected in parallel to the battery module 90 and the charging device 20 via the positive side wiring PL and the negative side wiring ML, respectively. The voltage detector 22 measures the voltage between the terminals of the battery module 90 and outputs the measured voltage value to the control device 10 as an electric signal.

The temperature detector 23 includes a temperature sensor arranged in the sensor mounting hole 220. The temperature sensor measures the temperature in the vicinity of the electrode plate group 140 of the corresponding cell 110 in the battery module 90, and outputs the measured temperature value to the control device 10 as an electric signal.

The temperature adjusting device 24 can set the battery temperature to a temperature suitable for regeneration by heating the battery module 90 or the like.
The control device 10 includes a computer having a calculation unit and a storage unit 15, and determines the battery state of the secondary battery through calculation processing in the calculation unit of the program stored in the storage unit 15 or the like. Performs various processes such as regenerating the next battery. The control device 10 obtains the charging current value of the battery module 90, the voltage value between terminals, and the battery temperature from each input electric signal. Further, the control device 10 can control the charging device 20, for example, charging with a constant current (CC) or charging with a constant voltage (CV). Therefore, the battery module 90 can be charged to adjust a predetermined SOC, for example, the SOC to "100%", or to overcharge.

The control device 10 includes an information acquisition unit 11 for acquiring external information, an SOC calculation unit 12 for calculating the battery SOC, and a charge control unit 13 for controlling the charging device 20. Further, the control device 10 adjusts the temperature of the regenerating unit 14 as an overcharging unit that performs regenerating processing of the battery module 90, the storage unit 15 that stores information required for arithmetic processing, and the temperature adjusting device 24. A temperature adjusting unit 16 is provided.

The information acquisition unit 11 acquires the charging current value from the current detector 21, the voltage value from the voltage detector 22, and the battery temperature from the temperature detector 23.
The SOC calculation unit 12 calculates the SOC of the battery module 90 from the charge / discharge history of the battery module 90 and the like. The SOC calculation unit 12 may calculate the SOC of the battery module 90 by a well-known method such as calculating the SOC from the voltage between the terminals of the battery module 90.

The charge control unit 13 controls the charging device 20 to charge the battery module 90.
The reproduction unit 14 controls the charge control unit 13 to overcharge and eliminate the negative charge reserve R3 to restore the charge capacity of the battery module 90, that is, a so-called reproduction process.

The temperature adjusting unit 16 adjusts the battery temperature of the battery module 90 to a temperature suitable for the regeneration process through the temperature adjusting of the temperature adjusting device 24.
The storage unit 15 stores information and the like necessary for arithmetic processing of the control device 10. For example, the storage unit 15 stores at least one of the map 60 and the relational expression (6) showing the relationship between the battery temperature for extinguishing the negative charge reserve R3 and the discharge current value.

(Operation of playback process)
With reference to FIG. 8, an operation procedure for regenerating the charge capacity of the battery module 90, which is regulated by the negative electrode, by the regenerating device 1 will be described.

In the reproduction process, the battery module 90 to be reproduced is electrically connected to the reproduction device 1 via the positive side wiring PL and the negative side wiring ML.
The reproduction device 1 acquires the charge reserve amount of the electrically connected battery module 90 (step S10). The charge reserve amount is calculated by the SOC calculation unit 12. The SOC calculation unit 12 calculates the charge reserve amount as a relative capacity difference between the SOC of the positive electrode and the SOC of the negative electrode of 100%. If the charge reserve amount is normal, it is acquired as a charge reserve R2 that is a relatively increased amount, and if it is a negative electrode regulation, it is acquired as a negative charge reserve R3 which is a relatively decrease amount.

The reproduction device 1 determines whether or not the charge reserve amount is less than "0Ah" (step S11). The charge reserve amount is "0 Ah" or more if there is a charge reserve R2, and less than "0 Ah" if there is a negative charge reserve R3.

When the reproduction device 1 determines that the charge reserve amount is not less than "0Ah" (NO in step S11), it is assumed that there is no need to regenerate the battery (step S12). Then, the reproduction device 1 ends the reproduction process.

On the contrary, when the reproduction device 1 determines that the charge reserve amount is less than "0Ah" (YES in step S11), the reproduction device 1 acquires the battery temperature (step S13).
The reproduction device 1 determines whether or not the acquired battery temperature is "25 ° C." or higher (step S14). "25 ° C." may be changed to a temperature suitable for other regeneration. The battery temperature is preferably the temperature inside the electrode plate group 140 in which the charging reaction occurs, but it is difficult to measure. Therefore, as the battery temperature, the temperature value measured by the temperature detector 23 may be used, or the measured temperature value may be corrected and used in consideration of the structure of the battery module 90 and the battery tank 130. ..

When the reproduction device 1 determines that the battery temperature is not "25 ° C." or higher (NO in step S14), the playback device 1 is set so that the battery temperature is "25 ° C." or higher (step S15). That is, the reproduction device 1 adjusts the set temperature of the temperature adjustment device 24 so that the battery temperature of the battery module 90 becomes a temperature of "25 ° C." or higher suitable for reproduction. Then, after the lapse of a predetermined time, the reproduction device 1 returns to the process of acquiring the battery temperature (step S13). The reproduction device 1 may end the reproduction process when the condition for stopping the generation process is satisfied, for example, when the battery temperature does not rise within a predetermined time.

When the reproduction device 1 determines that the battery temperature is "25 ° C." or higher (YES in step S14), the reproduction device 1 determines the charging current at which the gas ratio is 3.5 times or more (step S16). The charging current at which the gas ratio is 3.5 times or more is determined by at least one of the selection based on the map 60 and the calculation based on the relational expression (6).

Subsequently, the reproduction unit 14 of the reproduction device 1 supplies the determined charge current value to the battery module 90 at a constant current (CC) (step S17), and supplies the charge current value to the battery module 90 for a target charge amount. Charge up to (step S18). The overcharge step is composed of steps S17 and S18. The target charge amount is an amount at which the battery module 90 is overcharged. It should be noted that a current larger than the determined charging current value may be supplied until overcharging occurs.

By the above supply, overcharging is performed in which at least one of the relatively high battery temperature and the relatively small charging current is satisfied. Overcharging with the charging current determined here eliminates the negative charge reserve R3 of the battery module 90.

At this time, when the battery module 90 is overcharged, gas is generated in the electric tank 130 in a state where hydrogen gas is more than oxygen gas, and the gas pressure of the gas exceeds the valve opening pressure, so that the exhaust valve 210 Gas with a gas ratio of 3.5 times or more is released from. As a result, the concentration of hydrogen gas in the battery module 90 is relatively lowered, and hydrogen is separated from the hydrogen storage alloy of the negative electrode. The desorption of hydrogen eliminates the charged state of the hydrogen storage alloy of the negative electrode, expands the uncharged region, and lowers the SOC of the negative electrode, thereby increasing the relative charge capacity of the positive electrode with respect to the SOC. Then, as shown in FIG. 2C, the SOC of the negative electrode is set to be equal to or higher than the SOC of the positive electrode, as shown in the relative relationship between the negative electrode capacity M21 of the SOC of the negative electrode and the positive electrode capacity P21 of the SOC of the positive electrode. As a result, the battery module 90 has a positive electrode regulation in which the discharge side is regulated by the SOC "0%" of the positive electrode and the charging side is regulated by the SOC "100%" of the positive electrode, so that the charge capacity becomes equal to the positive electrode capacity P21. Recover to.

By charging the battery module 90 to the target charge amount, the reproduction device 1 stops the supply of the charging current (step S19), and ends the reproduction process.
As a result, the negative charge reserve R3 disappears, and the charge capacity of the battery module 90 is restored.

According to this embodiment, the effects described below can be obtained.
(1) Normally, a nickel-metal hydride secondary battery is generated at a gas ratio in which the number of hydrogen molecules is doubled with respect to the number of oxygen molecules due to overcharging. In this respect, the gas ratio, which is the ratio of hydrogen gas to oxygen gas generated by overcurrent, becomes 2.5 times or more, which is higher than twice the normal gas ratio. More hydrogen gas is discharged to the outside of the square case 300. The decrease in hydrogen gas in the square case 300 increases the charge reserve of the negative electrode by releasing hydrogen from the hydrogen storage alloy in order to maintain the partial pressure of hydrogen in the square case 300. As a result, the charge reserve of the nickel-metal hydride secondary battery can be restored.

(2) An appropriate gas ratio can be obtained by adjusting the charging current and the environmental temperature included in the predetermined conditions.
(3) Since the gas ratio is 3.5 times or more, more hydrogen gas can be discharged to the outside of the square case 300 to restore the charge reserve.

(4) Based on the relational expression (6), the charging current, the environmental temperature, and a predetermined ratio can be set to appropriate values for the regeneration process.
(5) By setting the charging current to 0.5 C or less, which is 0.5 times the rated current, the proportion of hydrogen gas contained in the gas generated by overcharging can be increased.

Further, when the charging current is 0.5 C or less, the gas ratio can be set to an appropriate value for the regeneration process even if the battery temperature is not high.
(6) By setting the battery temperature to 50 ° C. or higher, the proportion of hydrogen gas contained in the gas generated by overcharging can be increased.

Further, when the battery temperature is 50 ° C. or higher, the gas ratio can be set to an appropriate value for the regeneration process even if the charging current is not small.
The above embodiment can be modified and implemented as follows. The above embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

-In the above embodiment, the case where the reproduction device 1 is mounted on the vehicle (onboard) and the battery module 90 of the vehicle is regenerated based on real time or accumulated data is illustrated. However, the present invention is not limited to this, and a battery module or a cell removed from the vehicle may be regenerated.

-In the above embodiment, the case where the charging device 20 has a charging circuit has been illustrated, but the present invention is not limited to this, and the charging device 20 may have a discharging circuit. If charging and discharging can be performed, the SOC adjustment range of the battery module can be expanded.

-In the above embodiment, the case where the gas is discharged from the exhaust valve 210 has been exemplified. However, the present invention is not limited to this, and a battery module or a cell may be provided with an exhaust hole to exhaust gas having a gas ratio of 2.5 times or more. If the battery module or cell is removed from the vehicle, the holes made in the regeneration process can be closed after the regeneration process.

-In the above embodiment, the case of recovering the negative electrode regulation of the cell 110 of the battery module 90 has been illustrated, but the present invention is not limited to this, and the negative electrode regulation in the charging of the single cell may be eliminated, or a plurality of cases may be taken. The battery module having the above-mentioned cell may be regarded as one battery, and the negative electrode regulation in charging may be eliminated.

-In the above embodiment, the battery module 90 is applied to a battery module used as a power source for an electric vehicle or a hybrid vehicle, but the present invention is not limited to this, and other applications may be subject to negative electrode restrictions in charging. It may be applied as a power source for the device.

1 ... Reproduction device, 10 ... Control device, 11 ... Information acquisition unit, 12 ... SOC calculation unit, 13 ... Charge control unit, 14 ... Reproduction unit, 15 ... Storage unit, 16 ... Temperature control unit, 20 ... Charging device, 21 ... current detector, 22 ... voltage detector, 23 ... temperature detector, 24 ... temperature regulator, 60 ... map, 90 ... battery module, 100 ... integrated battery tank, 110 ... single battery, 120 ... partition wall, 130 ... electricity Tank, 140 ... electrode plate group, 141 ... positive electrode plate, 141a ... lead part, 142 ... negative electrode plate, 142a ... lead part, 143 ... separator, 150, 160 ... current collector plate, 151, 161 ... connection protrusion, 152, 153 ... Connection terminal, 170 ... Through hole, 200 ... Lid, 210 ... Exhaust valve, 220 ... Sensor mounting hole, 300 ... Square case.

Claims (7)

A method for regenerating a nickel-metal hydride secondary battery, which regenerates a nickel-metal hydride secondary battery having an electrolytic solution consisting of a positive electrode containing an active material containing nickel hydroxide as a main component, a negative electrode containing a hydrogen storage alloy, and an alkaline aqueous solution.
Hydrogen gas and oxygen gas are generated from the secondary battery whose negative charge reserve has disappeared by overcharging under predetermined conditions, and the internal pressure of the secondary battery case is used to open the exhaust valve that discharges the gas in the case. It is equipped with an overcharge step that raises the pressure to the outside and releases the gas in the case to the outside.
In the overcharge step, the gas ratio, which is the ratio of the number of hydrogen molecules (H ₂ ) to the number of oxygen molecules (O ₂ ) generated by the overcharge under the predetermined conditions, is increased by 2.5 times or more. How to regenerate the battery. The method for regenerating a nickel-metal hydride secondary battery according to claim 1, wherein the predetermined condition includes at least one of a charging current and a battery temperature. The method for regenerating a nickel-metal hydride secondary battery according to claim 1 or 2, wherein the gas ratio is 3.5 times or more. When the value of the gas ratio is a predetermined ratio,
Predetermined ratio = 2.601-0.048 x charging current [C] + 0.037 x battery temperature [° C]
The method for regenerating a nickel-metal hydride secondary battery according to any one of claims 1 to 3, further comprising a setting step for setting the charging current and the battery temperature satisfying the relational expression of the above. The method for regenerating a nickel-metal hydride secondary battery according to claim 4, wherein the charging current is 0.5 C or less. The method for regenerating a nickel-metal hydride secondary battery according to claim 4, wherein the battery temperature is 50 ° C. or higher. A nickel-metal hydride secondary battery regeneration device that regenerates a nickel-metal hydride secondary battery having an electrolytic solution consisting of a positive electrode containing an active material containing nickel hydroxide as a main component, a negative electrode containing a hydrogen storage alloy, and an alkaline aqueous solution.
By overcharging under predetermined conditions, hydrogen gas and oxygen gas are generated in the secondary battery in which the charge reserve of the negative electrode has disappeared, and the internal pressure of the case of the secondary battery is used to exhaust the gas in the case. It is equipped with an overcharge unit that raises the valve opening pressure to the outside and releases the gas inside the case to the outside.
The overcharge unit increases the gas ratio, which is the ratio of the number of hydrogen molecules (H ₂ ) to the number of oxygen molecules (O ₂ ) generated by the overcharge under the predetermined conditions, to 2.5 times or more. Battery regeneration device.

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