CN114300759B - Method for manufacturing nickel-hydrogen storage battery - Google Patents
Method for manufacturing nickel-hydrogen storage battery Download PDFInfo
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- CN114300759B CN114300759B CN202111142834.2A CN202111142834A CN114300759B CN 114300759 B CN114300759 B CN 114300759B CN 202111142834 A CN202111142834 A CN 202111142834A CN 114300759 B CN114300759 B CN 114300759B
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- metal hydride
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- 238000003860 storage Methods 0.000 title claims abstract description 140
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 52
- 239000001257 hydrogen Substances 0.000 title claims abstract description 49
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 45
- 229910052987 metal hydride Inorganic materials 0.000 claims abstract description 105
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 35
- 230000004913 activation Effects 0.000 claims abstract description 35
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 33
- 239000000956 alloy Substances 0.000 claims abstract description 33
- 239000011149 active material Substances 0.000 claims abstract description 7
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 claims abstract description 5
- 238000007789 sealing Methods 0.000 claims abstract description 4
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 3
- 238000013461 design Methods 0.000 claims description 7
- 238000005259 measurement Methods 0.000 claims description 7
- 230000003213 activating effect Effects 0.000 claims description 3
- 239000007789 gas Substances 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 10
- 238000001994 activation Methods 0.000 description 33
- 238000007599 discharging Methods 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 239000000047 product Substances 0.000 description 8
- 230000002950 deficient Effects 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 7
- -1 nickel metal hydride Chemical class 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 238000005192 partition Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910017052 cobalt Inorganic materials 0.000 description 4
- 239000010941 cobalt Substances 0.000 description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 4
- 150000002431 hydrogen Chemical class 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 238000003466 welding Methods 0.000 description 4
- 239000004743 Polypropylene Substances 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000006258 conductive agent Substances 0.000 description 2
- 239000011162 core material Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 2
- 229920001955 polyphenylene ether Polymers 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- OSOVKCSKTAIGGF-UHFFFAOYSA-N [Ni].OOO Chemical compound [Ni].OOO OSOVKCSKTAIGGF-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001869 cobalt compounds Chemical class 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000002736 metal compounds Chemical group 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000652 nickel hydride Inorganic materials 0.000 description 1
- 229910000483 nickel oxide hydroxide Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000006277 sulfonation reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
A method for manufacturing a nickel-metal hydride storage battery, which can suppress excessive gas generation during active charge and discharge after battery assembly and can effectively improve the activity of a hydrogen storage alloy. The method for manufacturing a nickel-hydrogen storage battery includes a positive electrode containing nickel hydroxide as an active material and a negative electrode containing a hydrogen storage alloy as an active material, and includes: an assembling step of sealing a battery in which a battery case is sealed with an electrolyte solution together with a plate group formed by stacking the positive electrode and the negative electrode with a separator interposed therebetween; and an activation charge/discharge step of performing a plurality of charge/discharge cycles and performing charge/discharge so as to increase the negative electrode SOC stepwise in accordance with the pre-measured charge efficiency of the negative electrode in at least a part of the charge/discharge cycles.
Description
Technical Field
The present invention relates to a method for manufacturing a nickel-metal hydride storage battery, and more particularly, to a method for manufacturing a nickel-metal hydride storage battery including an activated charge/discharge operation for a nickel-metal hydride storage battery in which the internal resistance is reduced.
Background
In recent years, alkali storage batteries have been attracting attention as power sources for portable devices, and the like, and as power sources for electric vehicles and hybrid vehicles. Among them, nickel-metal hydride storage batteries are secondary batteries including a positive electrode composed of an active material mainly composed of nickel hydroxide and a negative electrode mainly composed of a hydrogen storage alloy, and are widely used as power sources for those applications because of high energy density, excellent reliability, and the like.
Such a nickel-hydrogen storage battery has properties such that the activity of the hydrogen storage alloy immediately after the battery is assembled is low and the initial output thereof is low. Therefore, in order to activate such a hydrogen storage alloy, a proposal has been made.
Conventionally, as shown by a broken line in fig. 7 (b), it is common knowledge of a person skilled in the art to quickly activate a hydrogen absorbing alloy to increase the negative electrode SOC.
In particular, in the method for manufacturing a nickel-metal hydride storage battery described in patent document 1, the following manufacturing method is proposed: after cobalt charging, overcharge is performed for the first time (SOC 100 to 130%) during active charge/discharge for activating the negative electrode in a plurality of cycles. By performing such overcharge, the hydrogen absorbing alloy can be activated rapidly.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2010-153261
Disclosure of Invention
Problems to be solved by the invention
However, since the activity of the negative electrode is insufficient in the initial period, the charge receiving property is poor, and when the state of overcharge is set from the initial state as in patent document 1, gas may be generated and the pressure inside the battery may rise. The following problems are presented: when the valve is opened due to this pressure rise, it becomes a cause of deterioration of the battery. In addition, the back pressure device can be used to avoid the valve opening, but there is a problem that the manufacturing cost increases.
The invention aims to solve the problems that: in a method for manufacturing a nickel-metal hydride storage battery, excessive gas generation is suppressed during active charge and discharge after battery assembly, and the activity of a hydrogen storage alloy is effectively improved.
Means for solving the problems
In order to solve the above problems, a method for manufacturing a nickel-metal hydride storage battery according to the present invention includes a positive electrode including nickel hydroxide as an active material and a negative electrode including a hydrogen storage alloy as an active material, the method including: an assembling step of sealing a battery in which a battery case is sealed with an electrolyte solution together with a plate group formed by stacking the positive electrode and the negative electrode with a separator interposed therebetween; and an activation charge/discharge step of performing a plurality of charge/discharge cycles and performing charge/discharge of the nickel-metal hydride storage battery in such a manner that the negative electrode SOC is stepwise improved in accordance with the pre-measured negative electrode charge efficiency in at least a part of each charge/discharge cycle.
In the above-described charge/discharge cycle in the active charge/discharge step, the nickel-metal hydride storage battery may be charged with a negative electrode SOC of less than 100% of the charge efficiency.
In the above-described charge/discharge cycle in the active charge/discharge step, the nickel-metal hydride storage battery may be charged at a negative electrode SOC exceeding 70% of the charge efficiency.
In the above-described charge/discharge cycle in the active charge/discharge step, the nickel-metal hydride storage battery is preferably charged with a negative electrode SOC equal to the charge efficiency. Here, "equal" includes an error range, needless to say, and includes a range in which the valve opening risk due to gas generation can be sufficiently suppressed.
Effects of the invention
The method for manufacturing the nickel-metal hydride storage battery can inhibit excessive gas generation in the activated charge and discharge after the battery is assembled and effectively improve the activity of the hydrogen storage alloy.
Drawings
Fig. 1 is a schematic diagram showing the crystal structure of an alloy after discharge and during charge.
Fig. 2 is a block diagram showing a device for manufacturing a nickel-metal hydride storage battery according to the present embodiment.
Fig. 3 is a flowchart showing steps of a method for manufacturing a nickel-metal hydride storage battery according to the present embodiment.
Fig. 4 is a perspective view of a battery module 11 including a partial cross-sectional structure of a nickel-metal hydride storage battery manufactured by the manufacturing method of the nickel-metal hydride storage battery.
Fig. 5 is a flowchart showing steps of the negative electrode activation charge and discharge according to the present embodiment.
Fig. 6 is a graph showing PCT curves of the nickel-metal hydride storage battery according to the present embodiment.
Fig. 7 (a) is a graph showing the relationship between the negative electrode SOC [% ] and the negative electrode charging efficiency [% ] in each charge-discharge cycle in the step of the activation step measured in advance. Fig. 7 (b) is a graph showing the relationship of the negative electrode SOC [% ] for each charge-discharge cycle in the step of the activation step.
Fig. 8 is a graph showing the charge efficiency and the negative electrode SOC of the negative electrode in the 1 st to 10 th charge-discharge cycles of the present embodiment.
Fig. 9 is a graph comparing the DC resistance DC-IR of the conventional method for manufacturing a nickel-metal hydride storage battery with the DC resistance DC-IR of the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment.
Fig. 10 is a graph showing a nyquist diagram using an ac impedance method, which shows a nickel-metal hydride storage battery according to the related art and a nickel-metal hydride storage battery according to the present embodiment.
Detailed Description
An embodiment of the method for producing a nickel-metal hydride storage battery according to the present invention will be described below.
< summary of the embodiments >
< Battery Capacity of Nickel-Hydrogen storage Battery >
The capacity of the negative electrode of a nickel-metal hydride storage battery is theoretically determined by a capacity defined by the limit amount of hydrogen that can be absorbed and stored by the hydrogen storage alloy of the negative electrode. The capacity required herein is referred to as "design capacity". However, the hydrogen absorbing alloy is not sufficiently activated at the time of initial charge, and thus the negative electrode capacity according to the above theory cannot be satisfied. Here, the negative electrode SOC [% ] (State Of Charge) indicating the charging rate or the charging State Of the negative electrode is calculated by "remaining capacity/full Charge capacity×100", the theoretical full Charge State is defined as negative electrode SOC100%, and the full discharge State is defined as negative electrode SOC0%. Here, the "full charge capacity" is "design capacity" and is a theoretical value, and therefore, even if the nickel-metal hydride storage battery is charged at the time of initial charge, sufficient activation cannot be performed in practice, and therefore, the charged capacity is limited, and the negative electrode SOC does not become 100%.
Next, in the present embodiment, the "charge efficiency (%)" is set as: when the design capacity of the negative electrode was set to 100%, the negative electrode was fully charged at 0.3C and discharged until the negative electrode potential reached a capacity ratio of-0.7V/cell. In this case, the charging efficiency of the 1 st charge and discharge is the lowest, and when the charge and discharge cycle is repeated, the hydrogen storage alloy becomes active, so the charging efficiency gradually increases. The voltage of-0.7V/cell is a voltage corresponding to 0% of the negative electrode capacity in the battery of the present embodiment, and is a value different depending on the battery.
< principle of activation of Hydrogen absorbing alloy >
Next, an activation mechanism of the hydrogen absorbing alloy will be described. Fig. 1 is a schematic diagram showing the crystal structure of an alloy after discharge and during charge. As shown in fig. 1, when charging starts, the negative electrode SOC becomes the lowest, and the alloy lattice of the hydrogen storage alloy containing Mn and Ni absorbs and stores hydrogen H, and the hydrogen balance pressure of the negative electrode rises, so that the alloy lattice becomes an expanded state. The hydrogen storage alloy becomes a state of high hydrogen equilibrium at a high SOC in which a large amount of hydrogen H is absorbed.
When the charging is finished, then transfer to discharging is performed. When the discharge is started, hydrogen H is released, the negative electrode SOC gradually decreases from the maximum value, and at the end of the discharge, the negative electrode SOC becomes 0%. That is, hydrogen H is released from the negative electrode, the hydrogen balance of the negative electrode decreases, and the alloy lattice of the hydrogen storage alloy becomes a contracted state. When the hydrogen balance is high, fracture (crack) of the hydrogen storage alloy is promoted, and as a result, the surface area of the negative electrode increases due to micronization of the hydrogen storage alloy, and the internal resistance (direct current resistance DC-IR) of the negative electrode may decrease.
As a result, the contact area with the electrolyte, that is, the reaction area (active site) as the electrode material can be enlarged. That is, the reaction surface area of the alloy can be increased, and the DC resistance DC-IR reduction effect can be fully exhibited.
< feature of the present embodiment >
In this embodiment, the active charge/discharge step is performed after the assembly step of the assembled battery. At this time, a plurality of charge/discharge cycles are performed, and in at least a part of each charge/discharge cycle, charge/discharge is performed so that the negative electrode SOC is stepwise increased in accordance with the pre-measured charge efficiency of the negative electrode.
Prior to the activation charge/discharge step, the characteristics of the fabricated battery were tested in advance, and data were collected. In this test, the charge and discharge cycles were repeated in advance to determine the "charge efficiency" in each charge and discharge cycle.
Next, in the activation charge/discharge step, the nickel-metal hydride storage battery is charged at an SOC exceeding 70% of the charge efficiency and at an SOC not exceeding 100% of the charge efficiency in each charge/discharge cycle. The nickel-metal hydride storage battery is charged at an SOC exceeding 70% of the charging efficiency, whereby the hydrogen storage alloy is efficiently micronized. On the other hand, since the nickel-metal hydride storage battery is charged at an SOC of not more than 100% of the charging efficiency, the generation of gas in the battery can be suppressed, and therefore, the risk of opening the valve is reduced, and facilities such as a back pressure device are not required. In the present embodiment, the charging is performed such that the negative electrode SOC and the charging efficiency become equal.
The present embodiment will be described in detail below.
< apparatus for producing Nickel-Hydrogen storage Battery >
Fig. 2 is a block diagram of an apparatus for manufacturing a nickel-metal hydride storage battery according to the present embodiment. The nickel-metal hydride storage battery 1 is connected to a nickel-hydride storage battery manufacturing apparatus 2. The nickel-metal hydride storage battery manufacturing apparatus 2 includes a charging/discharging device 3, a voltage measuring device 4, a current measuring device 5, a thermometer 6, and a thermal insulation cooling device 7. The charge/discharge device 3, the voltage measuring device 4, the current measuring device 5, the thermometer 6, and the thermal insulation cooling device 7 are connected to the nickel-metal hydride storage battery 1. The charging/discharging device 3 charges and discharges the nickel metal hydride storage battery 1 at a predetermined charging/discharging rate. The voltage measuring device 4 measures the cell voltage of the nickel-metal hydride storage battery 1. The current measuring device 5 measures the current of the nickel-metal hydride storage battery 1. The thermometer 6 measures the cell temperature T of the nickel-metal hydride storage battery 1. The warm-keeping and cooling device 7 warms or cools the nickel-metal hydride storage battery 1 to adjust the battery temperature T. The control device 8 is configured as a known computer having a CPU81 and a memory 82 such as ROM/RAM, and controls the charge/discharge device 3 and the thermal insulation cooling device 7 based on data from the voltage measuring device 4, the current measuring device 5, and the thermometer 6.
< method for producing Nickel-Hydrogen storage Battery >
Fig. 3 is a flowchart showing steps of a method for manufacturing a nickel-metal hydride storage battery according to the present embodiment.
In the method for manufacturing the nickel-metal hydride storage battery 1, a battery module assembling process (S1) is first performed. Here, first, the battery cells (not shown) are assembled, and the battery module 11 (fig. 4) is assembled by connecting a plurality of the battery cells.
Next, an activation step (S2) is performed. Here, the charge and discharge are repeated by the charge and discharge device 3 under predetermined conditions, and the electrode is activated.
Next, a defective product determination step (S3) is performed to remove defective products. Then, finally, a battery pack, which is a battery pack as a product, is completed through a battery pack assembling process (S4).
< Battery Module Assembly Process (S1) >)
< Nickel-Hydrogen storage Battery >
Fig. 4 is a perspective view of a battery module 11 including a partial cross-sectional structure of a nickel-metal hydride storage battery manufactured by the manufacturing method of the nickel-metal hydride storage battery. As shown in fig. 4, the nickel-metal hydride storage battery of the present embodiment is a sealed battery, and is used as a power source for vehicles such as electric vehicles and hybrid vehicles. As a nickel-metal hydride storage battery mounted on a vehicle, a square sealed storage battery is known, which is configured by a battery module 11 configured by electrically connecting a plurality of unit cells 30 in series to obtain a required power capacity.
The battery module 11 has an integrated battery case 10 as a rectangular battery case, and the rectangular battery case is configured by a rectangular case 13 capable of accommodating a plurality of unit cells 30 and a lid 14 sealing an opening 16 of the rectangular case 13. A plurality of irregularities (not shown) for improving heat dissipation performance during use of the battery are formed on the surface of the square case 13.
The square case 13 and the lid 14 constituting the integrated battery case 10 are composed of polypropylene (PP) and polyphenylene ether (PPE) as resin materials having resistance to alkaline electrolyte. A partition wall 18 that divides the plurality of cells 30 is formed inside the integrated battery case 10, and a portion divided by the partition wall 18 becomes a battery case 15 for each cell 30. The 6 battery grooves 15 of the integrated battery groove 10 each constitute a single cell 30, for example.
In the battery case 15 thus divided, the electrode group 20, and the positive electrode collector plate 24 and the negative electrode collector plate 25 joined to both sides of the electrode group 20 are housed together with an alkaline electrolyte which is an aqueous dielectric containing potassium hydroxide (KOH) as a main component.
The electrode group 20 is formed by stacking rectangular positive electrode plates 21 and negative electrode plates 22 with separators 23 interposed therebetween. At this time, the direction in which the positive electrode plate 21, the negative electrode plate 22, and the separator 23 are stacked is the stacking direction. In the positive electrode plate 21 and the negative electrode plate 22 of the electrode plate group 20, the lead portions of the positive electrode plate 21 and the lead portions of the negative electrode plate 22 are configured by protruding toward the opposite side portions of the electrode plate in the surface direction, the current collector plate 24 is joined to the side edges of the lead portions of the positive electrode plate 21 by spot welding or the like, and the current collector plate 25 is joined to the side edges of the lead portions of the negative electrode plate 22 by spot welding or the like.
Further, a through hole 32 for connecting the battery cells 15 is formed in the upper portion of the partition wall 18. The through-holes 32 are connected to each other by welding, such as spot welding, through the through-holes 32 by connecting protrusions protruding from the upper portion of the current collector plate 24 and connecting protrusions protruding from the upper portion of the current collector plate 25, whereby the electrode plate groups 20 of the adjacent battery cells 15 are electrically connected in series. Of the through holes 32, the through holes 32 located outside the battery case 15 at both ends are provided with a positive electrode connection terminal 29a or a negative electrode connection terminal (not shown) above the end side wall of the integrated battery case 10. The connection terminal 29a of the positive electrode is welded to the connection protrusion of the current collector plate 24. The connection terminal of the negative electrode is welded to the connection protrusion of the current collector plate 25. The total output of the electrode group 20, that is, the plurality of unit cells 30 connected in series in this way is taken out from the positive electrode connection terminal 29a and the negative electrode connection terminal.
On the other hand, the cover 14 is provided with: an exhaust valve 33 for setting the internal pressure of the integrated battery container 10 to be equal to or lower than the valve opening pressure; and a sensor mounting hole 34 for mounting a sensor for detecting the temperature of the plate group 20. When the value of the internal pressure of the integrated battery container 10 communicated through a communication hole, not shown, in the upper portion of the partition wall 18 becomes equal to or higher than the valve opening pressure exceeding the allowable threshold value, the exhaust valve 33 opens to exhaust the gas generated in the integrated battery container 10. In addition, when the valve is opened, the generated gas is released, and the electrolyte is lost, which is not preferable. In addition, the back pressure device can avoid the pressure rise in the module, but the manufacturing device and the battery require additional devices, so that the production cost is increased, which is not preferable.
< Structure of electrode plate group 20 >
The positive electrode plate 21 includes a foamed nickel substrate as a metal porous body, a positive electrode active material containing nickel oxide as a main component, such as nickel hydroxide or nickel oxyhydroxide filled in the foamed nickel substrate, and an additive (a conductive agent or the like). The conductive agent is a metal compound, and a cobalt compound such as cobalt oxyhydroxide (CoOOH) and a nickel oxide are coated on the surface thereof.
The cobalt oxyhydroxide having high conductivity forms a conductive network in the positive electrode, and improves the utilization rate of the positive electrode (percentage of "discharge capacity/theoretical capacity").
The negative electrode plate 22 includes an electrode core material made of a punched metal plate or the like and a hydrogen storage alloy (MH) coated on the electrode core material.
The separator 23 is a nonwoven fabric of an olefin resin such as polypropylene, or a structure in which hydrophilic treatment such as sulfonation is performed as needed.
The battery module 11 is manufactured using the positive electrode plate 21, the negative electrode plate 22, and the separator 23.
< activation step (S2) >)
The activation step (S2) is performed by the CPU81 of the control device 8 of the nickel-metal hydride storage battery manufacturing apparatus 2 shown in fig. 2, and is composed of a positive electrode activation step and a negative electrode activation step.
< Positive electrode activation Process >
The positive electrode activation step is a step of charging the nickel-metal hydride storage battery to electrochemically oxidize cobalt contained in the positive electrode mixture and precipitate the cobalt as cobalt oxyhydroxide, thereby improving the electrical conductivity. In the positive electrode activation step, the assembled nickel-metal hydride storage battery is preferably charged for 1 to 5 hours at a rated current of 0.1 to 2.0A inclusive before charging. By charging the nickel-metal hydride storage battery under such conditions, it is possible to simultaneously reduce the resistance of the beta-form cobalt oxyhydroxide and precipitate cobalt.
< negative electrode activation Process >
Next, a negative electrode activation step is performed. Here, "activated charge and discharge" is performed. Fig. 5 is a flowchart showing steps of activated charge and discharge of the negative electrode according to the present embodiment.
< relationship between negative electrode SOC and activation >
Fig. 6 is a graph showing PCT curves of the nickel-metal hydride storage battery according to the present embodiment. In the negative electrode activation charge-discharge step of the present embodiment, the alloy of the negative electrode is micronized by charge-discharge, and the reaction surface area increases, so that the charge efficiency (hydrogen absorption and storage amount) of the negative electrode is optimized with activation of the negative electrode. The internal pressure of the hydrogen storage amount accompanying the negative electrode increases from about 70% or more of the negative electrode SOC in a PCT curve (P: pressure; C: hydrogen storage amount; T: temperature) indicating the equilibrium characteristic of the reaction of the hydrogen storage alloy and hydrogen. Therefore, the stress applied to the hydrogen absorbing alloy increases, and the region that promotes the pulverization of the negative electrode becomes a charged region of the negative electrode that greatly attains the effect of reducing the resistance. In this embodiment, since the negative electrode SOC is set to about 70% or more in each charge-discharge cycle, the micronization of the negative electrode is promoted.
< measurement of charging efficiency (S10) >)
Fig. 7 (a) is a graph showing a relationship between the negative electrode SOC [% ] and the negative electrode charging efficiency [% ] in each charge-discharge cycle in the step of the activation step measured in advance. Fig. 7 (b) is a graph showing the relationship of the negative electrode SOC [% ] for each charge-discharge cycle in the step of the activation step. The following describes the steps of activating charge and discharge according to the flowchart of fig. 5, with reference to fig. 7 (a) and 7 (b).
As shown in fig. 5, in the negative electrode activation charge/discharge step, the charge efficiency is measured (S10) before the charge step (S11). In the measurement of the charging efficiency (S10), the CPU81 of the control device 8 of the nickel-metal hydride storage battery manufacturing apparatus 2 shown in fig. 2 measures the characteristic of the charging efficiency of the nickel-metal hydride storage battery to be manufactured in advance.
In the measurement of the charging efficiency (S10), the nickel-metal hydride storage battery to be measured is assembled into a battery module, as in the normal battery module assembling step (S1), until the positive electrode is activated.
Then, the charge/discharge in the 1 st charge/discharge cycle is performed. Here, since the charging efficiency of the negative electrode is not clear, for example, the charging current is set to 0.3C, and the charging is performed for a sufficient time so as to be close to 100% of the design capacity. When the charging was completed, the discharge was started while measuring the discharge current, and the nickel-metal hydride storage battery was discharged until the negative electrode potential reached-0.7V/cell. Based on the discharge capacity obtained at this time, the design capacity was divided as a capacity ratio. In one example, the discharge capacity obtained at this time is divided by the design capacity to be set as a capacity ratio. This value is set to, for example, 50% for the charging efficiency.
In the 2 nd charge/discharge cycle, the nickel-metal hydride storage battery is charged with a current value of the anode SOC (for example, 80%) which becomes a level exceeding the initial capacity ratio in a range not exceeding 100% of the anode SOC. Then, the discharge was performed in this state, and the discharge capacity was measured. For example, assume that the charging efficiency here is 75%.
After the 3 rd charge/discharge cycle, the charge efficiency in each charge/discharge cycle was obtained by repeating the above steps. Here, it is assumed that the charge efficiency of the charge and discharge in the 3 rd cycle is 80%, and the charge efficiency of the charge and discharge in the 4 th cycle is 90%. In this way, the charging efficiency in each charging and discharging cycle is approximately obtained.
However, it is desirable to set the negative electrode SOC according to the charging efficiency based on the result of one measurement and to further repeatedly measure the battery using a different nickel-metal hydride storage battery newly manufactured. For example, in the case of the above example, in the 1 st charge/discharge cycle, the nickel-metal hydride storage battery is charged with a current value of the negative electrode SOC which is 70 to 100% of the measured charge efficiency, that is, 35% to 50%. Then, the charging efficiency in the 1 st charge/discharge cycle was calculated. In the same manner, in the 2 nd charge/discharge cycle, the nickel-metal hydride storage battery is charged with a current value of the negative electrode SOC which is 70 to 100% of the measured charging efficiency, that is, 53.9% to 75%.
In the initial measurement, the charging efficiency is unknown, and therefore, it is assumed that the nickel-metal hydride storage battery needs to be charged with a current exceeding the charging efficiency. However, when the nickel-metal hydride storage battery is charged with a larger current value exceeding the charging efficiency, the micronization of the hydrogen storage alloy is considered to proceed more than when the nickel-metal hydride storage battery is charged with a current value not exceeding the charging efficiency. In this case, in the 2 nd charge/discharge cycle, the charging efficiency is different from that of the actual production process. Therefore, by repeatedly adjusting the negative electrode SOC, which is the charging target, in a new battery and measuring the negative electrode SOC, it is possible to provide a battery with higher accuracy.
The number of charge/discharge cycles until the required DC resistance DC-IR [% ] is reached is determined by repeatedly measuring the DC resistance DC-IR [% ] for each charge/discharge cycle under such conditions. In the present embodiment, the number of charge/discharge cycles is set to 10 cycles, for example.
In this way, data of characteristics of the charging efficiency of the nickel-metal hydride storage battery to be manufactured are collected.
< setting of negative electrode SOC >
Regarding the target anode SOC, for example, it is assumed that the charge efficiency of the 1 st charge-discharge cycle is 50%. Regarding the target anode SOC, when the stored charge efficiency of the 1 st charge/discharge cycle is set to 50%, the nickel-metal hydride storage battery is charged with an anode SOC of 70 to 100%, that is, 35% to 50%, for example, with a current value of 40% at which the anode SOC becomes 90% of the charge efficiency.
Similarly, in the 2 nd charge/discharge cycle, when the stored charge efficiency in the 2 nd charge/discharge cycle is 75%, the nickel-metal hydride storage battery is charged with a current value of the negative electrode SOC of 70 to 100%, that is, 53.9% or more and 75% or less. The negative electrode SOC of each charge-discharge cycle determined based on the data is stored in advance in the memory 82 of the control device 8 of the nickel-metal hydride battery manufacturing apparatus 2 shown in fig. 2.
Fig. 8 is a graph showing the charge efficiency and the negative electrode SOC of the negative electrode in the 1 st to 10 th charge/discharge cycles of the present embodiment. When data is repeatedly collected in advance as described above, the charging efficiency of the negative electrode can be accurately measured, so that charging is performed at a negative electrode SOC equal to the charging efficiency of the negative electrode. When this is set, the most effective negative electrode activation can be performed while suppressing the generation of gas in a range where negative electrode charge can be received. Here, "equal" includes an error range, needless to say, and includes a range in which the valve opening risk due to gas generation can be sufficiently suppressed. For example, the term "equal" is used herein to refer to a range of about 10% to about 20%.
The charge and discharge cycle was 10 times. The number of times is set based on whether the DC resistance DC-IR is set to a desired value or whether the DC resistance DC-IR can be further improved even if the charge/discharge cycle is repeated.
< charging Process (S11) >)
Next, a charging process is performed (S11). In the charging step (S11), the nickel-metal hydride storage battery is charged at a low rate of, for example, 0.3C in the 1 st charge/discharge cycle. By performing at such a low rate, gas generation can be suppressed and activation can be performed.
In this charging step, the nickel-metal hydride storage battery is charged in advance so as to be the negative electrode SOC [% ] shown in fig. 8 stored in the memory 82 of the control device 8 of the nickel-metal hydride storage battery manufacturing apparatus 2 shown in fig. 2.
The negative electrode SOC is estimated by, for example, obtaining a map (not shown) of the negative electrode potential from a relationship between the battery open voltage OCV and the negative electrode potential in advance. Further, it may be estimated by a current integration method or the like that integrates the current flowing through the battery to estimate SOC, and detected by the current measuring device 5.
< determination of charging completion (S12) >)
Here, the CPU81 of the control device 8 of the nickel-metal hydride storage battery manufacturing apparatus 2 shown in fig. 2 monitors the battery open voltage OCV of the nickel-metal hydride storage battery by the voltage measuring device 4. The negative electrode SOC is estimated. When the negative electrode SOC is estimated as the target negative electrode SOC, it is determined that the charging is completed (S12: YES), the charging is stopped, and a discharging process is performed (S13).
< discharge Process (S13) >)
In the discharging step (S13), the discharge current is adjusted by a predetermined load resistance, and the CPU81 of the control device 8 of the apparatus 2 for manufacturing a nickel-metal hydride storage battery shown in fig. 2 monitors the battery open voltage OCV of the nickel-metal hydride storage battery by the voltage measuring device 4 to estimate the negative electrode potential.
< judgment of discharge completion (S14) >)
The nickel-metal hydride storage battery is discharged until the negative electrode potential reaches a negative electrode potential at which the negative electrode SOC is estimated to be 0% -0.7V/cell. The CPU81 of the control device 8 of the apparatus 2 for producing a nickel-metal hydride storage battery monitors the battery opening voltage OCV of the nickel-metal hydride storage battery by the voltage measuring device 4, and determines that the discharging process is completed (S13) when it is estimated that the negative electrode potential reaches-0.7V/cell (S14: yes).
< determination of completion of charging and discharging in a predetermined period (S15) >)
The CPU81 of the control device 8 of the nickel-metal hydride storage battery manufacturing apparatus 2 determines whether or not the predetermined number of charge/discharge cycles has been reached. When it is determined that the number of charge/discharge cycles performed has not reached the predetermined number (S15: NO), the charging process is returned to for the next charge/discharge cycle (S11). When it is determined that the number of charge/discharge cycles performed has reached the predetermined number (S15: yes), the negative electrode activation step is terminated.
< defective product determination step (S3) >)
Next, the description of the steps of the method for manufacturing a nickel-metal hydride storage battery is continued with reference to fig. 3. When the activation step (S2) is completed, a defective product determination step (S3) is performed.
Then, in the defective product determination step (S3), the initial defective of the battery module 11 is determined. The defective product determination of the battery is performed, for example, by an OCV inspection or a count interruption method.
< Battery assembly Process (S4) >)
In the assembled battery step (S4), the plurality of battery modules 11 thus manufactured are assembled into an assembled battery, not shown. The battery pack is configured as a battery pack provided on a vehicle or the like as a use partner. The battery pack is configured by connecting a plurality of activated battery modules 11, which are good, in series or in parallel electrically, stacking them, and mechanically fixing them, and further providing a control device, a measuring device, and the like.
Thus, the nickel-metal hydride storage battery as a product is completed.
(action of the present embodiment)
When the negative electrode is not activated as a characteristic of the nickel-metal hydride storage battery, the charging efficiency is low, and even if a current exceeding the charging efficiency is applied, the activation is not performed, but a gas is generated, and the risk of opening the valve increases, or a device for treating the gas is required. In the charge/discharge cycle of the present embodiment, the charge efficiency of the nickel-metal hydride storage battery is measured in advance, and the charge is managed so as not to become the negative electrode SOC exceeding the charge efficiency in each charge/discharge cycle. Therefore, even if there is no device for treating gas, gas is not generated and the risk of opening the valve is not increased. In this range, the most effective activation of the negative electrode is performed.
(effects of the present embodiment)
(1) According to the method for manufacturing a nickel-metal hydride storage battery of the present embodiment, it is more preferable that the negative electrode can be activated, and the reduction of the direct current resistance DC-IR can be effectively achieved.
Fig. 9 is a graph comparing the DC resistance DC-IR of the conventional method for manufacturing a nickel-metal hydride storage battery with the DC resistance DC-IR of the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment. When the DC resistance DC-IR of the conventional method for manufacturing a nickel-metal hydride storage battery was set to 100%, the effect was confirmed to be significant when the DC resistance DC-IR of the method for manufacturing a nickel-metal hydride storage battery of the present embodiment was 98%.
Fig. 10 is a graph showing a nyquist diagram using an ac impedance method, which shows a nickel-metal hydride storage battery according to the related art and a nickel-metal hydride storage battery according to the present embodiment. When compared with the conventional nickel-metal hydride storage battery shown by the broken line, the zero-crossing of the nickel-metal hydride storage battery of the present embodiment shown by the straight line shifts to the left, and the radius of the circular arc portion decreases. This means that the resistance decreases when electrons of the electrolyte, the electrode posts, the collector plates, and the like move. That is, it was confirmed that the micronization of the negative electrode was being performed.
(2) The reduction of the direct current resistance DC-IR can be effectively realized, and therefore, the performance of the nickel-metal hydride storage battery can be improved.
(3) In the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment, characteristics of the charging efficiency of the nickel-metal hydride storage battery to be manufactured are measured in advance, and charge and discharge are performed with activation of the negative electrode suitable for the characteristics. Therefore, the negative electrode activation charge and discharge is performed in advance under the most appropriate conditions for the nickel-metal hydride storage battery to be manufactured.
(4) In the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment, the method can be applied without modifying a general nickel-metal hydride storage battery, and therefore has versatility and can suppress production costs.
(5) In the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment, the control of the charging current alone can be performed without requiring a special device such as a back pressure device, and therefore, the production cost can be reduced.
(6) In the method for manufacturing a nickel-metal hydride storage battery according to the present embodiment, since the method can be automatically performed by controlling only the charging current, the method is extremely easy to perform and can be accurately performed without skill.
(other examples)
The above embodiment can be implemented as follows.
The flowcharts shown in fig. 3 and 5 are examples, and those skilled in the art can change the order of those steps, add steps, or omit steps.
It is needless to say that the structure can be added, deleted, or changed by those skilled in the art without departing from the scope of the invention.
Description of the reference numerals
1: nickel-hydrogen storage battery
2: apparatus for manufacturing nickel-hydrogen storage battery
3: charging and discharging device
4: voltage measuring device
5: current measuring device
6: thermometer
7: thermal insulation cooling device
8: control device
81：CPU
82: memory device
11: battery module
13: square shell
20: polar plate group
21: positive plate
22: negative plate
23: partition board
33: exhaust valve
DC-IR: DC resistor (internal resistance)
Claims (4)
1. A method for manufacturing a nickel-metal hydride storage battery having a positive electrode containing nickel hydroxide as an active material and a negative electrode containing a hydrogen storage alloy as an active material, the method comprising:
an assembling step of sealing a battery in which a battery case is sealed with an electrolyte solution together with a plate group formed by stacking the positive electrode and the negative electrode with a separator interposed therebetween; and
an activation charge/discharge step of activating a positive electrode after the assembly step and a negative electrode after the positive electrode;
a charging efficiency measurement step performed before the negative electrode activation step,
in the negative electrode activation step, a plurality of charge/discharge cycles are performed, and from the initial charge/discharge cycle, in the charge efficiency measurement step, the charge/discharge of the nickel-metal hydride storage battery is performed so as to increase the negative electrode SOC stepwise according to the pre-measured charge efficiency of the negative electrode,
the charging efficiency is a ratio of a discharge capacity of the nickel-metal hydride storage battery when the nickel-metal hydride storage battery is discharged to a voltage corresponding to 0% of a negative electrode capacity after actual full charge divided by a design capacity, which is a theoretical capacity when the negative electrode SOC is 100%.
2. The method for manufacturing a nickel-metal hydride storage battery according to claim 1, wherein,
each of the charge-discharge cycles in the activated charge-discharge step charges the nickel-metal hydride storage battery at a negative electrode SOC of less than 100% of the charge efficiency.
3. The method for manufacturing a nickel-metal hydride storage battery according to claim 1 or 2, wherein,
each of the charge and discharge cycles in the activated charge and discharge step charges the nickel-metal hydride storage battery at a negative electrode SOC exceeding 70% of the charge efficiency.
4. The method for manufacturing a nickel-metal hydride storage battery according to claim 1, wherein,
and charging the nickel-metal hydride storage battery at a negative electrode SOC equal to the charging efficiency in each of the charge-discharge cycles in the activated charge-discharge step.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020169893A JP7271488B2 (en) | 2020-10-07 | 2020-10-07 | Method for manufacturing nickel-metal hydride storage battery |
| JP2020-169893 | 2020-10-07 |
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| CN114300759A CN114300759A (en) | 2022-04-08 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4716088A (en) * | 1986-12-29 | 1987-12-29 | Energy Conversion Devices, Inc. | Activated rechargeable hydrogen storage electrode and method |
| JP2010135339A (en) * | 2010-02-05 | 2010-06-17 | Gs Yuasa Corporation | Nickel-hydrogen storage battery and method of manufacturing the same |
| JP2010153261A (en) * | 2008-12-25 | 2010-07-08 | Panasonic Ev Energy Co Ltd | Manufacturing method of nickel metal hydride storage battery |
| CN104919643A (en) * | 2013-04-12 | 2015-09-16 | 朴力美车辆活力股份有限公司 | Method for restoring battery capacity, method for restoring battery assembly capacity, device for restoring battery capacity, and device for restoring battery assembly capacity |
| CN109786797A (en) * | 2017-11-10 | 2019-05-21 | 中国科学院大连化学物理研究所 | A kind of zinc-nickel single flow battery anode activation method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5642577B2 (en) * | 2010-03-18 | 2014-12-17 | 三洋電機株式会社 | Alkaline storage battery and alkaline storage battery system |
-
2020
- 2020-10-07 JP JP2020169893A patent/JP7271488B2/en active Active
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2021
- 2021-09-28 CN CN202111142834.2A patent/CN114300759B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4716088A (en) * | 1986-12-29 | 1987-12-29 | Energy Conversion Devices, Inc. | Activated rechargeable hydrogen storage electrode and method |
| JP2010153261A (en) * | 2008-12-25 | 2010-07-08 | Panasonic Ev Energy Co Ltd | Manufacturing method of nickel metal hydride storage battery |
| JP2010135339A (en) * | 2010-02-05 | 2010-06-17 | Gs Yuasa Corporation | Nickel-hydrogen storage battery and method of manufacturing the same |
| CN104919643A (en) * | 2013-04-12 | 2015-09-16 | 朴力美车辆活力股份有限公司 | Method for restoring battery capacity, method for restoring battery assembly capacity, device for restoring battery capacity, and device for restoring battery assembly capacity |
| CN109786797A (en) * | 2017-11-10 | 2019-05-21 | 中国科学院大连化学物理研究所 | A kind of zinc-nickel single flow battery anode activation method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114300759A (en) | 2022-04-08 |
| JP2022061756A (en) | 2022-04-19 |
| JP7271488B2 (en) | 2023-05-11 |
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