Alkaline secondary battery and method for manufacturing alkaline secondary battery

Abstract

Provided is an alkaline secondary battery and a method for manufacturing an alkaline secondary battery, which can effectively suppress the generation of Ni2O3H. The alkaline secondary battery includes a positive electrode plate (2) including a positive electrode substrate (21) composed of porous Ni or Ni alloy and a positive electrode composite layer, and an alkaline electrolyte (24), the positive electrode composite layer containing particles (22a) of a positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate (21), and in the alkaline secondary battery, dendrites of NiO are continuously present in a dendritic shape from the positive electrode substrate (21) to a particle surface (22b) of the positive electrode active material, and at the particle surface (22b), 0.245 ≤ NiO / Ni(OH)2 ≤ 1.77. According to the alkaline secondary battery, the generation of Ni2O3H can be effectively suppressed.

Description

Technical Field

[0001] This invention relates to alkaline secondary batteries and methods for manufacturing alkaline secondary batteries. More specifically, it relates to alkaline secondary batteries and methods for manufacturing alkaline secondary batteries that can suppress capacity reduction caused by the formation of Ni2O3H. Background Technology

[0002] Conventionally, as described in Patent Document 1, nickel positive plates used in alkaline batteries are mostly manufactured by impregnating a porous nickel sintered substrate formed by sintering nickel powder in a reducing atmosphere with an acidic solution containing nickel salt as the main component. After concentration, the substrate is immersed in a hot alkaline solution, and a positive electrode active material containing nickel hydroxide as the main component is filled into the pores of the nickel substrate.

[0003] When using a nickel sintered substrate without a nickel oxide layer to fill the active material via chemical impregnation, the acidic impregnation solution corrodes the nickel sintered body, reducing the mechanical strength of the electrode. Therefore, Patent Document 1 discloses a method to prevent corrosion of the nickel sintered body by forming a nickel oxide layer on its surface.

[0004] Furthermore, in alkaline batteries using nickel hydroxide as the positive electrode, under certain repeated charge-discharge conditions, electrochemically inert Ni₂O₃H (nickel oxide) is generated, which can lead to an increase in battery resistance and a decrease in battery capacity. Therefore, the invention described in Patent Document 2 proposes a current density of 100 A / m 2 A proposal for a Ni2O3H battery with a total capacity of 10kAh when charging and discharging within a SOC range of 20% to 80% is proposed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 1987-211860

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-233423 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the invention described in Patent Document 2, Ni2O3H (even in minute amounts) is generated during continuous use at a specified capacity (Ah). Once Ni2O3H is generated, it substantially increases ΔSOC, causing an irreversible reduction in battery capacity and leading to further generation of Ni2O3H.

[0011] This will result in a sharp decrease in capacity, so a fundamental strategy to suppress Ni2O3H is essential.

[0012] The problem to be solved by the alkaline secondary battery and the method for manufacturing the alkaline secondary battery of the present invention is to effectively suppress the formation of Ni2O3H.

[0013] Methods for solving problems

[0014] To address the aforementioned issues, the alkaline secondary battery of the present invention comprises a positive electrode plate consisting of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte. The positive electrode substrate is composed of porous Ni or a Ni alloy, and the positive electrode composite material layer contains particles of positive electrode active material, primarily Ni(OH)2, filled within the positive electrode substrate. The alkaline secondary battery is characterized in that NiO is present on the surface of the particles of the aforementioned positive electrode active material.

[0015] In the above alkaline secondary battery, the surface composition of the positive electrode active material particles can satisfy 0.245≤NiO / Ni(OH)2≤1.77.

[0016] Among the aforementioned alkaline secondary batteries, the alkaline secondary battery can be a nickel-metal hydride battery.

[0017] Furthermore, in the method for manufacturing the alkaline secondary battery of the present invention, the alkaline secondary battery is an alkaline secondary battery comprising a positive electrode plate composed of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte. The positive electrode substrate is composed of porous Ni or Ni alloy, and the positive electrode composite material layer contains particles of positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate. The method for manufacturing the alkaline secondary battery is characterized in that, in the state where Ni(OH)2 is filled in the positive electrode substrate, the temperature T [°C], humidity M [%], and time t [h] are controlled to promote the growth of NiO generated by the positive electrode substrate through air-based oxidation until it reaches the surface of the particles of the positive electrode active material inside the pores.

[0018] In the above-mentioned method for manufacturing alkaline secondary batteries, the temperature T ≤ 35°C and the humidity M ≤ 90%.

[0019] In the above-described method for manufacturing an alkaline secondary battery, when the positive electrode capacity lifetime [%] of the alkaline secondary battery, in which NiO is absent from the surface of the positive electrode active material particles, is 100 [%], the value of NiO / Ni(OH)2 can be adjusted so that the positive electrode capacity lifetime [%] is within a set threshold. In this case, the surface composition of the positive electrode active material particles can be adjusted to 0.245 ≤ NiO / Ni(OH)2.

[0020] In the above-described method for manufacturing an alkaline secondary battery, when the internal resistance [%] of the alkaline secondary battery, in which NiO is absent from the surface of the positive electrode active material particles, is 100 [%], the value of NiO / Ni(OH)2 can be adjusted so that the internal resistance [%] is within a set threshold. In this case, the composition of the surface of the positive electrode active material particles can be adjusted to NiO / Ni(OH)2 ≤ 1.77.

[0021] In the above-described method for manufacturing an alkaline secondary battery, the alkaline secondary battery comprises a positive electrode plate consisting of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte. The positive electrode substrate is made of porous Ni or a Ni alloy, and the positive electrode composite material layer contains particles of positive electrode active material, primarily Ni(OH)2, filled within the positive electrode substrate. The positive electrode plate of the alkaline secondary battery is configured such that, with Ni(OH)2 filled in the positive electrode substrate, oxidation based on air is promoted to form the positive electrode substrate... The growth of NiO produced by the material continues until it reaches the surface of the positive electrode active material particles inside the pores. In the positive electrode plate, when a[g] of the alkaline electrolyte is added to the positive electrode plate, if the electrolyte that permeates into the positive electrode plate and is absorbed is b[g], and the electrolyte that permeates into the positive electrode plate and flows out to the lower part is c[g], the permeability [%] = c[g] / a[g]. The NiO / Ni(OH)2 ratio on the surface of the positive electrode active material particles is adjusted in such a way that the permeability [%] ≥ 40[%).

[0022] The effects of the invention

[0023] The alkaline secondary battery and its manufacturing method according to the present invention can effectively suppress the formation of Ni2O3H. Attached Figure Description

[0024] Figure 1(a) is a schematic diagram showing the reaction on the particle surface of the positive electrode active material of a nickel-metal hydride battery during charging. Figure 1(b) shows the reaction equations of the normal positive electrode main reaction during discharge and the side reaction when oxygen is generated and local electrolyte drying occurs.

[0025] Figure 2 This is a schematic diagram showing the reaction of the particle surface of the positive electrode active material during charging when NiO is formed on the particle surface of the positive electrode active material grown on the particle surface of the nickel-metal hydride battery.

[0026] Figure 3 This is a schematic diagram showing the NiO on the surface of the positive electrode substrate and the positive electrode active material grown from the positive electrode substrate into the nickel-metal hydride battery.

[0027] Figure 4This is a partial cross-sectional view of the battery module 90 of the nickel-metal hydride battery according to this embodiment.

[0028] Figure 5 This is a graph showing the change in NiO / Ni(OH)2 under varying temperature and humidity conditions.

[0029] Figure 6 This is a graph showing the relationship between the change in NiO / Ni(OH)2 and the internal resistance [%) and the positive electrode capacity lifetime [%).

[0030] Figure 7 This is a schematic diagram illustrating the method for calculating permeability.

[0031] Figure 8 This is a graph showing the relationship between the change in NiO / Ni(OH)2 and the permeability [%).

[0032] Figure 9 This is a graph showing the determination of the particle surface of the positive electrode active material in a nickel-metal hydride battery using XPS analysis peaks.

[0033] Figure 10 This is a graph comparing the lifespan of nickel-metal hydride batteries with those of existing technologies and those of this embodiment. Detailed Implementation

[0034] The alkaline secondary battery and its manufacturing method of the present invention will be described with reference to Figures 1-10 through an embodiment of a nickel-metal hydride battery and a method thereof.

[0035] <Principle of this implementation method>

[0036] The purpose of the nickel-metal hydride battery and its manufacturing method in this embodiment is to effectively suppress the formation of Ni2O3H. Therefore, the formation mechanism of Ni2O3H will be explained first.

[0037] <Surface of positive electrode active material particles>

[0038] Figure 1(a) is a schematic diagram showing the oxygen in the reaction on the particle surface of the positive electrode active material of a nickel-metal hydride battery during charging.

[0039] Figure 1(b) shows the reaction equations of the normal positive electrode main reaction during discharge and the abnormal side reaction when oxygen is generated, causing local "electrolyte drying".

[0040] <Main Reactions at the Positive Electrode During Discharge>

[0041] The positive electrode active material particles 22a change between Ni(OH)2 and β-NiOOH during charging and discharging. It should be noted that, for ease of explanation, the positive electrode active material is sometimes described as Ni(OH)2. The normal main reaction of the nickel-metal hydride battery during discharge is shown in the following equation (1), which, in the presence of H2O, generates Ni(OH)2 and OH from β-NiOOH. - In this case, the H2O in the electrolyte is consumed and reduced. - It functions as an alkaline ion in the alkaline electrolyte 24. Under these conditions, oxygen (O2) and hydrogen (H2) gases are not generated through the exchange of ions and electrons.

[0042] β-NiOOH + H₂O + e - →Ni(OH)2+OH - ……(1)

[0043] <Oxygen generation based on side reactions and the occurrence of "electrolyte drying">

[0044] The potential at the positive electrode may increase. And when the electrolysis potential of H2O is reached, H2O electrolysis will occur as a side reaction. In the electrolysis of H2O, O2 is generated at the positive electrode through the reaction of the following formula (2).

[0045] 4OH - →O2 + 2H2O + 4e - ……(2)

[0046] As shown in Figure 1(a), when the surface 22b of the positive electrode active material Ni(OH)2 / β-NiOOH becomes high potential through charging, the side reaction shown in equation (2) above occurs, generating O2 bubbles A on the surface 22b of the positive electrode active material. During charging, when O2 is generated at the positive electrode, O2 bubbles A adhere to the surface 22b of the positive electrode active material. Over time, these O2 bubbles A detach from the surface 22b of the positive electrode active material. Thus, the detached portion of bubble A comes into contact with the alkaline electrolyte 24, supplying H2O and OH-. - .

[0047] However, depending on the conditions, it may take time for the O2 generated on the surface 22b of the positive electrode active material particles, such as bubble B, to detach from the particle surface 22b. Thus, O2 bubbles like bubble B attached to the particle surface of the positive electrode active material will block the alkaline electrolyte. As a result, H2O and OH- on the surface of the positive electrode active material... - Physically excluded, this portion becomes a localized "electrolyte-drying" state. H2O, OH... - None of them exist here in a physical form.

[0048] <Generation of Ni2O3H based on "electrolyte drying">

[0049] Therefore, in the normal reaction, as shown in equation (1) of Figure 1(b), H2O is required in the reaction. However, in the case of "electrolyte drying out" without supplying H2O, an abnormal side reaction will occur when the nickel-metal hydride battery is discharged, forming the reaction of equation (3) below.

[0050] 16β-NiOOH+4e - →8Ni₂O₃H⁺ + 2H₂O + O₂ + 4OH⁻ - ……(3)

[0051] That is, the reaction occurs without the use of H2O, and instead produces H2O. Furthermore, Ni2O3H, O2, and OH are generated as products in this reaction. - O2 is steadily absorbed by the negative electrode (recombining reaction) over time as shown in equation (4), maintaining a closed system. - It is returned to the alkaline electrolyte.

[0052] 4MH + O2 → 4M + 2H2O……(4)

[0053] Here, Ni₂O₃H is an electrochemically inert product. Its formation involves irreversible accumulation, leading to increased battery resistance and decreased battery capacity. Therefore, the formation of Ni₂O₃H is generally discouraged as an undesirable reaction.

[0054] <Memory Effect of Nickel-Metal Hydrate Batteries>

[0055] It is known that in nickel-metal hydride batteries, repeated charging and discharging at low state of charge (SOC) can produce a memory effect. In a battery system with a memory effect, the voltage shifts to the higher potential side (high potential side), so even at the same SOC, the voltage will increase, and O2 is particularly easily generated. As a result, localized electrolyte drying occurs instantaneously at the oxygen-generated sites on the surface 22b of the positive electrode active material particles, thus generating Ni2O3H simultaneously with the reaction of insufficiently generated H2O, as shown in equation (3) above. When Ni2O3H is generated, it leads to a sharp decrease in capacity.

[0056] <Structure of this embodiment>

[0057] To suppress these phenomena, it is necessary to prevent localized electrolyte drying. The inventors believe that, to suppress localized electrolyte drying, it is necessary to improve the diffusivity of the alkaline electrolyte 24 on the surface of the positive electrode plate 2. Therefore, alkaline electrolyte 24 can be rapidly supplied to address localized electrolyte drying caused by O2 generation on the particle surface 22b of the positive electrode active material. This allows the OH- in the alkaline electrolyte 24 to... - H2O immediately fills the areas where the electrolyte has dried up, effectively inhibiting the formation of Ni2O3H.

[0058] Therefore, the inventors discovered that, as a specific technical solution, by ensuring that NiO is sufficiently present on the particle surface 22b of the positive electrode active material, the surface tension of the particle surface 22b of the positive electrode active material can be increased. When the surface tension of the particle surface 22b of the positive electrode active material increases, the wettability of the alkaline electrolyte 24 decreases, thereby improving the diffusivity of the alkaline electrolyte 24.

[0059] By configuring it in this way, alkaline electrolyte 24 can be rapidly supplied to address localized electrolyte drying on the particle surface 22b of the positive electrode active material due to O2 generation. This allows the OH- in the electrolyte to be absorbed quickly. - H2O immediately fills the areas where the electrolyte has dried up, effectively inhibiting the formation of Ni2O3H.

[0060] <Reaction during charging in this embodiment>

[0061] Figure 2 This is a schematic diagram showing the reaction of the particle surface 22b of the positive electrode active material during charging, in the case where NiO is formed on the particle surface 22b of the positive electrode active material grown in the nickel-metal hydride battery.

[0062] like Figure 2 As shown, during charging, the positive electrode potential rises due to memory effect and other factors, reaching the electrolysis potential of H2O, resulting in the electrolysis of H2O as a side reaction. During the electrolysis of H2O, O2 is generated at the positive electrode through a side reaction.

[0063] In this case, in the existing nickel-metal hydride battery shown in Figure 1(a), the generated oxygen adheres to the surface of the positive electrode active material particles 22b, such as bubble B, to produce “electrolyte drying”, as shown in Equation (3) of Figure 1(b), and sometimes Ni2O3H is generated.

[0064] On the other hand, in the nickel-metal hydride battery of this embodiment, such as Figure 2As shown, by ensuring that NiO22d is fully present on the particle surface 22b of the positive electrode active material, the surface tension of the particle surface 22b of the positive electrode active material is increased. When the surface tension of the particle surface 22b of the positive electrode active material increases, the wettability of the alkaline electrolyte 24 decreases, and the diffusivity of the alkaline electrolyte 24 increases. Thus, bubbles C and D easily detach from the particle surface 22b of the positive electrode active material and quickly contact the alkaline electrolyte, H2O, OH-. - When supplied to this part, it constitutes the normal reaction of formula (1) in Figure 1(b), effectively suppressing the formation of Ni2O3H.

[0065] <Comparison with existing technologies>

[0066] In the existing method disclosed in Patent Document 1, a nickel oxide (NiO) coating is formed on the positive electrode substrate of the positive electrode plate. The purpose is that, when using a nickel sintered substrate without a nickel oxide layer and filling the active material by chemical impregnation, the acidic impregnation solution corrodes the nickel sintered body, reducing the mechanical strength of the electrode plate. Therefore, in the invention described in Patent Document 1, corrosion of the nickel sintered body is prevented by forming a nickel oxide layer on the surface of the nickel sintered body. Therefore, NiO only covers the surface of the positive electrode substrate 21.

[0067] The relatively high resistivity of NiO22d increases the internal resistance when used to cover the cathode substrate 21, which is a drawback. Furthermore, covering the Ni(OH)2-based positive electrode active material particles 22a within the cathode substrate 21 with NiO poses a significant risk of increased internal resistance. Therefore, even when NiO is necessary to protect the cathode substrate from corrosion, covering the positive electrode active material particles 22a with NiO22d has historically been contrary to common sense.

[0068] <Summary of the function / effect of this implementation method>

[0069] In this embodiment, the NiO22d on the surface 22b of the positive electrode active material particles does not cover its surface. The NiO22d generated by the positive electrode substrate 21 expands in a dendritic shape. As a result, the NiO22d on the surface 22b of the positive electrode active material particles becomes dendritic, thereby forming gaps, ensuring direct contact between the positive electrode active material particles 22a and the alkaline electrolyte 24, and suppressing the increase of internal resistance.

[0070] On the other hand, the NiO22d on the particle surface 22b of the positive electrode active material has sufficient area, which increases the surface tension of the particle surface 22b on the positive electrode active material and reduces the wettability of the alkaline electrolyte 24. As a result, sufficient diffusion of the alkaline electrolyte is ensured.

[0071] Therefore, in this embodiment, the balance of the ratio of NiO22d to Ni(OH)222c on the particle surface 22b of the positive electrode active material can be appropriately adjusted.

[0072] Therefore, by suppressing the rise in internal resistance and improving the diffusivity of alkaline electrolyte 24, the formation of Ni2O3H can be suppressed and the capacity life of nickel-metal hydride batteries can be extended.

[0073] (Specific configuration of this embodiment)

[0074] Figure 3 This is a schematic diagram showing the positive electrode substrate 21 and the NiO22d on the Ni(OH)222c of the particle surface 22b of the positive electrode active material grown from the positive electrode substrate into the nickel-metal hydride battery.

[0075] like Figure 3 As shown, the positive electrode substrate 21 of the positive electrode plate 2 has a three-dimensional mesh-like framework portion 21a. Holes 21b, serving as spaces, are formed between the framework portions 21a. A composite material containing aggregates 22e of particles 22a containing positive electrode active material is filled into these holes 21b. Furthermore, OH groups are present in these holes 21b. - The alkaline electrolyte 24 permeates into H2O.

[0076] The aggregate 22e of the positive electrode active material particles 22a is maintained in contact with the framework portion 21a of the positive electrode substrate 21. The positive electrode substrate 21 is made of Ni or a Ni alloy, which is a porous metal, and NiO22d is generated on its surface by oxidation. In this embodiment, the crystals are grown until the NiO22d of the positive electrode substrate reaches the particle surface of the positive electrode active material by appropriately controlling the temperature T [°C], humidity M [%], and time t [h]. Therefore, dendritic crystals reach the particle surface 22b of the positive electrode active material, and the dendritic NiO22d expands in a manner that covers the particle surface 22b of the positive electrode active material. Thus, on the particle surface 22b of the positive electrode active material, a portion of the substrate Ni(OH)222c is exposed, and a portion is covered by dendritic NiO22d. In this embodiment, by appropriately controlling the temperature T [°C], humidity M [%], and time t [h], the surface 22b of the positive electrode active material particles is configured in a manner that satisfies 0.245 ≤ NiO / Ni(OH)2 ≤ 1.77.

[0077] The following is a brief description of an example of a nickel-metal hydride battery and its manufacturing method, which are the premises of this embodiment.

[0078] Nickel-metal hydride batteries

[0079] Figure 4 A partial cross-sectional view of the battery module 90 of the nickel-metal hydride battery according to this embodiment is shown. Figure 4 As shown, nickel-metal hydride (NiMH) batteries are sealed batteries used as power sources in vehicles such as electric vehicles and hybrid vehicles. To achieve the required electrical capacity, NiMH batteries installed in vehicles are known to be square, sealed secondary batteries composed of battery modules 90, which are formed by connecting multiple individual cells 110 in series.

[0080] The battery module 90 has a rectangular housing 300 in the shape of a cuboid. The housing consists of an integrated battery compartment 100 capable of housing multiple individual batteries 110 and a cover 200 that seals the integrated battery compartment 100. It should be noted that the housing 300 can be made of resin.

[0081] The integral battery tank 100 constituting the square casing 300 is made of a synthetic resin material (e.g., polypropylene, polyethylene, etc.) resistant to alkaline electrolytes. Furthermore, partitions 120 for separating multiple individual cells 110 are formed inside the integral battery tank 100, and the portions separated by these partitions 120 constitute the battery tank 130 for each individual cell 110. For example, the integral battery tank 100 has six battery tanks 130. Figure 4 The image shows a portion of its four electrical slots 130.

[0082] The electrode assembly 140, along with the positive electrode current collector 150 and the negative electrode current collector 160 connected to its two sides, are housed together with the electrolyte in the thus separated electrode cell 130.

[0083] The electrode assembly 140 is constructed by laminating rectangular positive electrode 2 and negative electrode 142 with a separator 143 in between. The direction in which the positive electrode 2, negative electrode 142, and separator 143 are laminated (perpendicular to the plane of the paper) is the lamination direction. The positive electrode 141 and negative electrode 142 of the electrode assembly 140 protrude from opposite sides in the direction of the plate surface (along the plane of the paper), thereby forming the lead-out portion 141a of the positive electrode 141 and the lead-out portion 142a of the negative electrode 142. Current collectors 150 and 160 are respectively engaged with the side edges of these leads 141a and 142a.

[0084] Additionally, a through hole 170 for connecting each of the electrical trays 130 is formed on the upper part of the partition wall 120. Regarding the through hole 170, two connecting protrusions 151 and 161, protruding from the upper part of the current collector plate 150 and the upper part of the current collector plate 160, are welded together through the through hole 170. This connects the electrode plate assemblies 140 of adjacent electrical trays 130 in series. In the through hole 170, a positive terminal 152 or a negative terminal (not shown) is installed on the upper side wall of the integral electrical tray 100 at the outer side of the through hole 170 located at both ends of the electrical tray 130. The positive terminal 152 is welded to the connecting protrusion 151 of the current collector plate 150. The negative terminal 153 is welded to the connecting protrusion 161 of the current collector plate 160. The total output of the electrode assembly 140, which is connected in series like this, i.e., multiple single cells 110, is taken out from the positive terminal 152 and the negative terminal.

[0085] On the other hand, the cover 200 constituting the square housing 300 is provided with an exhaust valve 210 to keep the internal pressure of the square housing 300 below the valve opening pressure, and a sensor mounting hole 220 for mounting a sensor for detecting the temperature of the electrode assembly 140. The sensor mounting hole 220 extends within the electrode tank 130 to the vicinity of the electrode assembly 140, thereby enabling the measurement of the temperature of the electrode assembly 140.

[0086] The exhaust valve 210 is used to maintain the internal pressure within the integrated electric bath 100 below an acceptable threshold. When the internal pressure exceeds the valve opening pressure of the acceptable threshold, the valve is opened to release the gas generated inside the integrated electric bath 100. The internal pressure of the integrated electric bath 100 is homogenized throughout the electric bath 130 through a communication hole (not shown) formed in the partition wall 120. Thus, gas is released from the integrated electric bath 100 until the homogenized internal pressure throughout the electric bath 130 is lower than the valve opening pressure, maintaining its internal pressure below the acceptable valve opening pressure.

[0087] <Composition of the electrode assembly 140>

[0088] <Positive Plate 2>

[0089] In the positive electrode plate 2, the positive electrode substrate 21, which serves as the substrate, is a foamed nickel three-dimensional porous body made of Ni or a Ni alloy, which is a porous metal. The positive electrode substrate 21 has a framework portion 21a containing a three-dimensional mesh structure and pore portions 21b surrounded by the framework portion 21a. The positive electrode substrate 21 is manufactured, for example, by applying nickel plating to the surface of a foamed urethane framework and then burning off the foamed urethane. The positive electrode plate 2 includes a positive electrode composite material layer 22 containing Ni(OH)2 and Co as active materials. Specifically, a suitable amount of conductive agent such as cobalt hydroxide and metallic cobalt powder, and if necessary, a thickener such as carboxymethyl cellulose and a binder such as polytetrafluoroethylene are added to granular nickel hydroxide, and it is first processed into a paste. Then, the processed material, which has become a paste, is filled into the mesh-like pore portions 21b of the positive electrode substrate 21 to form the positive electrode composite material layer 22. It is then dried, rolled, and cut to form a plate-shaped positive electrode plate 2.

[0090] It should be noted that the composition of NiO in positive plate 2 will be explained in detail below.

[0091] <Negative electrode plate 142>

[0092] The negative electrode plate 142 is constructed, for example, using a hydrogen storage alloy as the active material. This hydrogen storage alloy is composed of a mixture of rare earth metals, nickel, aluminum, cobalt, and manganese, which are mixtures of rare earth elements such as lanthanum, cerium, and neodymium. More specifically, a conductive agent such as carbon black, and, if necessary, a thickener such as carboxymethyl cellulose and a binder such as styrene-butadiene copolymer, are added to the hydrogen storage alloy, and it is first processed into a paste. Subsequently, after the hydrogen storage alloy, which has been processed into a paste, is coated or filled onto a core material such as a perforated metal (active material support), it is dried, rolled, and cut to form the negative electrode plate 142, which is also plate-shaped.

[0093] <Separator 143>

[0094] As the spacer 143, a nonwoven fabric made of olefin resin such as polypropylene can be used, or a component obtained by subjecting it to hydrophilic treatment such as sulfonation as required.

[0095] The battery module 90 of the nickel-metal hydride battery in this embodiment has the above configuration.

[0096] <Formation of NiO in particles 22a of the positive electrode active material of positive electrode plate 2>

[0097] Here, the formation of NiO in the positive electrode active material particles 22a of the positive electrode plate 2, which is a feature of this embodiment, will be described in detail.

[0098] The feature of this embodiment is that the crystallization of NiO generated in the positive electrode substrate 21 extends continuously in a dendritic form on the surface of the particles 22a of the positive electrode active material filled in the positive electrode substrate 21.

[0099] <Method for manufacturing the positive electrode plate 2>

[0100] In a specific method for manufacturing the positive electrode plate 2, first, the positive electrode plate 2 composed of the positive electrode substrate 21 and the positive electrode composite material layer 22 is manufactured. The positive electrode substrate 21 is made of porous Ni or Ni alloy, and the positive electrode composite material layer 22 contains particles 22a of a positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate 21.

[0101] In a state where Ni(OH)2 is filled in the positive electrode substrate 21 of the positive electrode plate 2, the growth of NiO generated from the positive electrode substrate 21 by oxidation based on air can be promoted, and dendritic crystallization of NiO continuous in the form of dendrites is caused to grow to reach the surface 22b of the particles of the positive electrode active material inside the pore portion.

[0102] <Control of the growth of NiO>

[0103] In the method for manufacturing the nickel-hydrogen storage battery of this embodiment, it is necessary to cause NiO generated from the positive electrode substrate 21 to continuously grow in the form of dendritic crystals to the particles 22a of the positive electrode active material. Conventionally, even if NiO is generated from the positive electrode substrate 21, the NiO does not grow to the surface 22b of the particles of the positive electrode active material in the form of dendritic crystals. Of course, NiO that increases the internal resistance is not caused to grow either. Therefore, in this embodiment, the growth of the crystallization of NiO is controlled by controlling the temperature T [°C], humidity M [%], and time t [h]. In one example, the temperature T [°C], humidity M [%], and time t [h] in the oxidation treatment based on air are controlled so that NiO generated from the positive electrode substrate 21 continuously grows in the form of dendritic crystals to the particles 22a of the positive electrode active material.

[0104] Figure 5 It is a graph showing the change in NiO / Ni(OH)2 when the conditions of temperature and humidity are changed. It shows the results of an experiment in which a composite material containing particles 22a of a positive electrode active material is filled in the pore portion 21b of the positive electrode substrate 21 and oxidized in the atmosphere.

[0105] As shown by the existing curve L1 represented by white dots, especially when the generation of NiO is not required, it is placed without special environmental management. For example, in a drying process or the like, it is in a state where the temperature T is 35 [°C] and the humidity M is 90 [%]. In this case, even after 3 weeks, the ratio of NiO / Ni(OH)2 only increases from 0.2 to about 0.4.

[0106] On the other hand, in this embodiment, represented by the black dot on curve L2, the environment was managed as follows: temperature T = 10°C and humidity M[%] = 10%. As a result, after 3 weeks, the NiO / Ni(OH)2 ratio increased from 0.2 to approximately 0.8. It was confirmed that by performing air oxidation at low temperature and low humidity, the area of ​​Ni(OH)2 could be reduced and the area ratio of NiO could be increased.

[0107] It should be noted that, through a crystallization growth process of 3 weeks (approximately 500 hours), dendrites of NiO22d generated from the cathode substrate 21 grow into the interior of the aggregate 22e of the cathode active material particles 22a disposed in the pores 21b of the cathode substrate 21. Furthermore, it was confirmed that the dendritic NiO22d crystals grow in a manner extending into the surface 22b of the cathode active material particles within the aggregate 22e.

[0108] The inventors have determined that, in order to enable NiO crystals to grow in a short time, it is preferable to keep the temperature T ≤ 35°C and the humidity M ≤ 90%.

[0109] <Adjustment of NiO / Ni(OH)2 value based on cathode capacity lifetime [%)>

[0110] Figure 6 This is a graph showing the relationship between the change in the NiO / Ni(OH)2 value of the surface composition of the positive electrode active material particles and the positive electrode capacity lifetime [%). Figure 6 In the figure shown, curve L4, represented by the upward-sloping dashed line, is a graph showing the relationship between the NiO / Ni(OH)2 value and the cathode capacity lifetime [%). As described above, the inventors discovered that increasing the area of ​​the NiO-covered cathode active material particle surface 22b can suppress the formation of Ni2O3H. This graph shows the change in cathode lifetime due to variations in the NiO / Ni(OH)2 value, assuming a cathode capacity lifetime of 100% when the NiO value is zero. A significant effect is observed when the NiO / Ni(OH)2 value is 0.245, resulting in a cathode capacity lifetime of approximately 106%. Subsequently, the value extends to approximately 130% when the NiO / Ni(OH)2 value is 1.75, and approximately 116% when the NiO / Ni(OH)2 value is 0.5. The cathode capacity lifetime is approximately 124% when the NiO / Ni(OH)2 value is 1.12. Furthermore, it was confirmed that when the NiO / Ni(OH)2 value is 1.75, the positive electrode capacity lifetime is extended to approximately 128% or more. Therefore, from the perspective of positive electrode capacity lifetime, the higher the NiO / Ni(OH)2 value, the better. It is also known that a NiO / Ni(OH)2 value of at least 0.245 can significantly extend the positive electrode lifetime.

[0111] <Adjustment of NiO / Ni(OH)2 value based on internal resistance [%)>

[0112] in addition, Figure 6 It is also a graph showing the relationship between the change in NiO / Ni(OH)2 and the internal resistance [%). Figure 6 In the figure shown, curve L5, represented by the solid line descending to the right, is a graph showing the relationship between the NiO / Ni(OH)2 value and the internal resistance [%). As described above, the inventors have discovered that when the area of ​​the particle surface 22b of NiO covering the positive electrode active material increases, although the formation of Ni2O3H can be suppressed, the internal resistance [%) increases.

[0113] The internal resistance [%] here refers to the value when the internal resistance is 100% assuming the NiO value is zero. This internal resistance [%] represents the ease of flow, expressed as the current value under constant voltage. As the resistance of NiO increases from 100%, this internal resistance [%] decreases. That is, as the resistance increases, this value decreases. When the NiO / Ni(OH)2 value is approximately 0.09, the internal resistance is approximately 100%. When the NiO / Ni(OH)2 value is approximately 0.84, the internal resistance is 99.8%. When the NiO / Ni(OH)2 value is approximately 1.14, the internal resistance is 99.4%. Furthermore, when the NiO / Ni(OH)2 value is approximately 1.77, the internal resistance is 98.7%, indicating an increase in internal resistance. It has also been confirmed that when the NiO / Ni(OH)2 value increases to 1.77, the internal resistance [%] increases sharply. Therefore, from the viewpoint of internal resistance, a smaller NiO / Ni(OH)2 value is better. However, it has been confirmed that even with a NiO / Ni(OH)2 value of 1.77, the internal resistance still reaches a sufficient value for the product, which is 98.7%. Therefore, it can be concluded that a sufficient resistance value for the product can be obtained at least when the NiO / Ni(OH)2 value is below 1.77.

[0114] <Adjustment of NiO / Ni(OH)2 based on permeability [%)>

[0115] Figure 7 This is a schematic diagram illustrating the method for calculating permeability [%).

[0116] Here, regarding the permeability [%] in this embodiment, when a[g] of alkaline electrolyte 24 is added dropwise to the positive electrode plate 2 made of foamed Ni, let b[g] be the amount of alkaline electrolyte that permeates into and is absorbed by the positive electrode plate 2. Let c[g] be the amount of alkaline electrolyte that permeates into the positive electrode plate 2 and further flows out to the lower part. In this case, the permeability [%] is the value obtained by permeability [%] = c[g] / a[g]. In other words, the permeability when the alkaline electrolyte is added dropwise to the positive electrode plate is expressed by permeability [%] = c[g] / a[g], where a[g] is the amount of alkaline electrolyte added, b[g] is the amount of alkaline electrolyte that permeates into and is absorbed by the positive electrode plate, and c[g] is the amount of alkaline electrolyte that permeates into the positive electrode plate and further flows out to the lower part. That is, the alkaline electrolyte c[g] that permeates into the positive electrode plate 2 and is further discharged through the positive electrode plate 2 and flows out to the lower part is an electrolyte that adheres to the inside of the positive electrode plate but is not retained therein. That is, NiO, with its high surface tension and low wettability, repels the alkaline electrolyte, so the alkaline electrolyte cannot remain in the positive electrode plate 2, and can be said to have high diffusivity. On the other hand, regarding the alkaline electrolyte b[g] that permeates into the positive electrode plate 2 and is absorbed, since it lacks NiO, has low surface tension, and high wettability, the positive electrode plate 2 absorbs and retains the alkaline electrolyte, so the alkaline electrolyte remains in the positive electrode plate 2, and can be said to have low diffusivity.

[0117] Furthermore, with a high permeability [%), NiO, with its high surface tension and low wettability, repels the alkaline electrolyte. Thus, O2 generated on the particle surface 22b of the positive electrode active material forms bubbles C and D in the alkaline electrolyte, and the alkaline electrolyte on the particle surface 22b of the positive electrode active material, along with bubbles C and D, is repelled. Therefore, the alkaline electrolyte constituting bubbles C and D cannot remain on the particle surface 22b of the positive electrode active material for long and separates within a short time. Because bubbles C and D separate from the particle surface 22b of the positive electrode active material in a short time, alkaline electrolyte 24 can be rapidly supplied to address the localized electrolyte drying caused by O2 adhering to the particle surface 22b of the positive electrode active material.

[0118] like Figure 3As shown, the positive electrode plate 2, made of foamed Ni, is a porous component with multiple pores 21b, into which particles 22a of the positive electrode active material are filled. In such a positive electrode plate 2, where NiO is absent, the highly wettable surface 22b of the positive electrode active material particles adheres to and is fixed to the alkaline electrolyte 24, preventing the alkaline electrolyte 24 from freely moving among the particles 22a filled in the pores 21b. That is, the alkaline electrolyte 24 has low diffusivity. On the other hand, when NiO is present and the surface 22b of the low-wettability positive electrode active material particles repels the alkaline electrolyte 24, the alkaline electrolyte 24 can freely move among the particles 22a filled in the pores 21b. That is, the alkaline electrolyte 24 has high diffusivity. When the alkaline electrolyte 24 has high diffusivity, if the alkaline electrolyte 24 penetrates into the porous positive electrode plate 2, it can easily reach the particle surface 22b of the positive polarization active material filling the pores 21b, thus making it less likely for the electrolyte to dry out.

[0119] Figure 8 This is a graph showing the relationship between the change in NiO / Ni(OH)2 and the permeability [%). Figure 8 Curve L3 shows that when the NiO / Ni(OH)2 value is 0.61 and 0.72, the permeability [%] is approximately 40%. With NiO / Ni(OH)2 values ​​of 0.61 and 0.72, approximately 40% of the alkaline electrolyte 24 diffuses into the interior of the positive electrode plate 2 and can move freely. Furthermore, when the NiO / Ni(OH)2 value is 0.79, the permeability [%] increases to approximately 60%, and approximately 60% of the alkaline electrolyte 24 diffuses into the interior of the positive electrode plate 2.

[0120] Furthermore, when the NiO / Ni(OH)2 ratio is 1.83, the permeability [%] is approximately 100%, and almost all of the added alkaline electrolyte 24 diffuses into the interior of the positive electrode plate 2. Therefore, the alkaline electrolyte 24, which can move freely inside the positive electrode plate 2, can easily reach the particle surface 22b of the positive polarization active material filling the pores 21b, thus preventing electrolyte drying.

[0121] As explained above, based on the conclusion derived from curve L3, further increasing the NiO / Ni(OH)2 value to obtain a higher permeability [%) will result in an even higher permeability [%). Furthermore, it is known that when the NiO / Ni(OH)2 value is at least 0.61 or higher, the permeability [%) is at least 40%, and the diffusivity of the alkaline electrolyte 24 is sufficiently high. Therefore, to ensure a permeability [%) of at least 40%, it is preferable to have a NiO / Ni(OH)2 value of 0.61 or higher.

[0122] Assembly of NiMH Batteries

[0123] In the positive electrode 2, negative electrode 142, and separator 143 manufactured in this way, the positive electrode 2 and negative electrode 142 are alternately stacked with the separator 143 in a manner that protrudes to opposite sides, thereby forming a cuboid electrode assembly 140. The outer edge of the lead-out portion 141a of each positive electrode 2, which protrudes to one side and is stacked, is bonded to the current collector 150 by spot welding or the like, and the outer edge of the lead-out portion 142a of each negative electrode 142, which protrudes to the other side and is stacked, is bonded to the current collector 160 by spot welding or the like.

[0124] The electrode groups 140, which are welded together by the current collectors 150 and 160, are housed in the electrical trays 130 within the square housing 300. The current collectors 150 of the positive electrode and 160 of the adjacent electrode groups 140 are connected by spot welding or the like between the connecting protrusions 151 and 161 protruding from their upper parts. Therefore, the adjacent electrode groups 140 are electrically connected in series.

[0125] In each of the battery cells 130, a specific amount of alkaline aqueous solution (electrolyte) with potassium hydroxide as the main component is injected, and the opening of the integrated battery cell 100 is sealed by the cover 200. This constitutes a battery module 90 with a rated capacity of, for example, "6.5Ah", formed by multiple individual cells 110 (nickel-metal hydride batteries). Such battery modules 90 are further combined and housed in a resin housing, and control devices, various sensors, etc. are installed, and the battery is mounted as a vehicle battery pack (see Figure 1) as a drive battery for the vehicle.

[0126] (The function of this implementation method)

[0127] <Composition of the particle surface of the positive electrode active material in nickel-metal hydride batteries>

[0128] Figure 9 This graph shows the particle surface measurements of the positive electrode active material of a nickel-metal hydride battery using XPS (X-ray photoelectron spectroscopy) analysis peaks. The vertical axis represents the intensity of emitted photoelectrons ([cps]), and the horizontal axis represents the binding energy of the atomic nucleus relative to the measured electron ([eV]). It can be seen that Ni(OH)₂ shows a peak around 531 [eV], and NiO shows a peak around 529 [eV]. Figure 9 As shown, the outermost curve G1 displays peaks for Ni(OH)2 and NiO. This indicates that approximately equal amounts of Ni(OH)2 and NiO exist on the particle surface 22b of the positive electrode active material in the nickel-metal hydride battery. Therefore, the NiO / Ni(OH)2 ratio is approximately 1.

[0129] Furthermore, when performing internal analysis with increased X-ray intensity, the peaks for NiO and Ni(OH)2 were absent in curves G2 and G3, with only a peak near 530 eV. This indicates that Ni(OH)2 and NiO exist only on the particle surface of the positive electrode active material in the nickel-metal hydride battery. In other words, NiO22d partially covers the particle surface 22b of the positive electrode active material originally composed of Ni(OH)2. This is because NiO is originally obtained by oxidizing the Ni in the positive electrode substrate composed of foamed Ni, and it originates from the Ni in the positive electrode substrate. On the other hand, NiO is not generated from Ni(OH)2. That is, this is because NiO is generated by oxidizing the Ni in the positive electrode substrate, and this NiO forms dendrites (dendritic crystals with multiple branches of different shapes), which can grow from the positive electrode substrate to the particle surface of the positive electrode active material.

[0130] In addition, surface analysis of the positive electrode substrate made of foamed Ni was conducted, and it was found that no diffraction peak of Ni2O3H was observed.

[0131] Lifespan of NiMH Batteries

[0132] Figure 10 This is a graph comparing the lifespan of existing nickel-metal hydride batteries with that of this embodiment. Curve L6 represents the lifespan of existing nickel-metal hydride batteries. As shown by curve L6, in existing nickel-metal hydride batteries where NiO is absent from the particle surface 22b of the positive electrode active material, the battery capacity [Ah] decreases rapidly as the total discharge energy [Ah] increases. That is, the battery life is relatively short.

[0133] Curve L7 is a graph representing the lifespan of the nickel-metal hydride battery of this embodiment. According to this curve, in the nickel-metal hydride battery of this embodiment, where NiO extends from the positive electrode substrate 21 to the particle surface 22b of the positive electrode active material, the decrease in battery capacity [Ah] is minimal even with an increase in total discharge energy [Ah]. That is, the battery life is relatively long.

[0134] In the past, based on the technical knowledge of those skilled in the art, it is necessary to suppress the formation of NiO as much as possible from the perspective of reduced conductivity. However, as shown in the nickel-metal hydride battery of this embodiment, when NiO extends from the positive electrode substrate 21 to the particle surface 22b of the positive electrode active material, the internal resistance is slightly reduced. However, this loss is minimal and can be fully compensated for by significantly extending the battery life.

[0135] (Effects of the implementation method)

[0136] The nickel-metal hydride battery and its manufacturing method according to this embodiment have the above-described configuration, and therefore exhibit the following effects.

[0137] (1) Compared with existing nickel-metal hydride batteries, it effectively suppresses the formation of Ni2O3H and achieves a significant lifespan extension.

[0138] (2) Even if the NiO with high resistance extends from the cathode substrate 21 to the particle surface 22b of the cathode active material, the NiO on the particle surface 22b of the cathode active material is dendritic crystal, which makes the gaps sufficient. Therefore, Ni(OH)2 will also be exposed and directly contact the electrolyte, thereby suppressing the rise of internal resistance.

[0139] (3) On the other hand, by extending NiO with high surface tension and low wettability from the cathode substrate 21 to the particle surface 22b of the cathode active material, the diffusion of the permeated alkaline electrolyte 24 on the cathode substrate 21 and the particle surface 22b of the cathode active material can be improved.

[0140] (4) Furthermore, by extending NiO, which has high surface tension and low wettability, from the cathode substrate 21 to the particle surface 22b of the cathode active material, the time for bubbles C and D generated on the particle surface 22b of the cathode active material to detach can be shortened. This rapidly eliminates the lack of H2O and OH- on the particle surface 22b of the cathode active material. - The electrolyte is in a "dried-up" state. As a result, the formation of Ni2O3H caused by side reactions can be effectively suppressed.

[0141] (5) When Ni(OH)₂ is filled in the cathode substrate 21, the growth of NiO generated from the cathode substrate 21 by air-based oxidation can be promoted. In this case, the temperature T [°C], humidity M [%], and time t [h] are controlled so that the growth of NiO, for example, the dendritic crystallization of NiO, reaches the particle surface 22b of the cathode active material inside the pores. In this way, the growth of dendritic crystals of NiO extending from the cathode substrate 21 to the particle surface 22b of the cathode active material can be promoted in a short time. In particular, by keeping the temperature T ≤ 35 [°C] and the humidity M ≤ 90 [%], NiO formation can be carried out in a short time.

[0142] (6) Since the crystals of NiO extend into dendrites, the crystals of NiO can also be uniformly formed on the surface 22b of the positive active material particles contained in the depth of the positive electrode composite material layer 22.

[0143] (7) The battery life and internal resistance of nickel-metal hydride batteries can be arbitrarily set by controlling the value of NiO / Ni(OH)2.

[0144] For example, if only battery life is considered, the value should be adjusted to 0.245 ≤ NiO / Ni(OH)2. On the other hand, if only internal resistance is considered, the value should be adjusted to NiO / Ni(OH)2 ≤ 1.77.

[0145] (8) If the balance between battery life and internal resistance of nickel-metal hydride battery is considered, then within the range of 0.245≤NiO / Ni(OH)2≤1.77, if battery life is important, set it to a larger value, and if internal resistance is important, set the value of NiO / Ni(OH)2 to a smaller value.

[0146] (9) In addition, if it is confirmed that NiO has the diffusion properties of the assumed alkaline electrolyte, a permeability test can be performed to adjust the permeability [%), thereby controlling the battery life and internal resistance.

[0147] (10) In this embodiment, in the existing nickel-metal hydride battery manufacturing process, with Ni(OH)2 filled in the positive electrode substrate 21, the growth of dendritic crystals of NiO generated by air-based oxidation from the positive electrode substrate 21 is promoted. Furthermore, this growth can be carried out by controlling only the temperature T [°C], humidity M [%], and time t [h] so that the dendritic crystals reach the particle surface 22b of the positive electrode active material inside the pore 21b. Therefore, no new equipment is required, and the manufacturing cost is not increased.

[0148] (11) This embodiment can be applied to conventional nickel-metal hydride batteries without changing the configuration, and therefore can be widely used.

[0149] (12) In this embodiment, a positive electrode substrate 21 is provided, which is made of porous Ni or Ni alloy. A positive electrode plate 2 is provided, which is made of a positive electrode composite material layer 22 containing particles 22a of positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate 21. However, it can be implemented as long as it is an alkaline secondary battery with alkaline electrolyte 24, and is not limited to nickel-metal hydride batteries.

[0150] (Modified Example)

[0151] The above-described implementation method can also be carried out as follows.

[0152] • In this embodiment, a nickel-metal hydride battery for vehicles that produces a memory effect is specifically illustrated, but needless to say, it can also be applied to batteries that do not produce a memory effect.

[0153] Furthermore, it is not limited to automotive applications; it can also be effectively used as a battery in ships, aircraft, and for example, in homes or factories.

[0154] • The shape of the battery is not limited to a rectangular battery module in the shape of a plate; it can be cylindrical or other shapes, and there is no limitation on its shape.

[0155] • Additionally, as an example of an alkaline secondary battery, a nickel-metal hydride battery is shown. However, it can be widely used in batteries that have a positive electrode plate consisting of a positive electrode substrate (which is composed of porous Ni or Ni alloy), a positive electrode composite layer (which contains particles of positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate), and an alkaline electrolyte.

[0156] Regarding the positive electrode plate 2 of this embodiment, an example is shown where foamed Ni is produced by burning off the foamed urethane after nickel plating is applied to the surface of the urethane backbone of the foamed urethane. However, this is not a limitation. It can also be a porous nickel sintered substrate formed by sintering nickel powder under a reducing atmosphere, as described in the prior art. There is no limitation as long as the positive electrode substrate is made of porous Ni or a Ni alloy.

[0157] • Regarding alkaline electrolyte 24, an alkaline aqueous solution (electrolyte) with potassium hydroxide as the main component is shown as an example, but it is not limited to this.

[0158] Regarding the numerical ranges illustrated in this embodiment, preferred examples corresponding to the configuration of this embodiment are shown. Therefore, those skilled in the art can, of course, appropriately optimize the numerical ranges based on the battery configuration, etc.

[0159] The manufacturing process shown in this embodiment is an example. Those skilled in the art can change the order of these operations or add or omit operations to implement them.

[0160] Furthermore, those skilled in the art can certainly implement the structure by adding, removing, or modifying it, as long as they do not depart from the claims.

[0161] Explanation of symbols

[0162] 2…Positive plate

[0163] 21… Positive electrode substrate

[0164] 21a…Skeletal section

[0165] 21b…hole

[0166] 22… Positive electrode composite material layer

[0167] 22a… (particles of positive electrode active material)

[0168] 22b… (the surface of the positive electrode active material) particles

[0169] 22c…Ni(OH)2

[0170] 22d…NiO

[0171] 24…Alkaline electrolyte

[0172] 90… Battery Module

[0173] 100…Integrated Electric Sink

[0174] 110…Single battery

[0175] 120… next door

[0176] 130…electrical tank

[0177] 140…plate assembly

[0178] 141a… Introduction

[0179] 142… Negative electrode plate

[0180] 142a… Introduction

[0181] 143…spacer

[0182] 150… collector board

[0183] 151… Connecting protrusion

[0184] 152…Connecting terminal

[0185] 153…Connecting terminal

[0186] 160… collector board

[0187] 161…connecting protrusion

[0188] 170…through hole

[0189] 200… Cover

[0190] 210…exhaust valve

[0191] 220… Sensor mounting hole

[0192] 300… square shell

[0193] A, B, C, D… bubbles

Claims

1. An alkaline secondary battery comprising a positive electrode plate composed of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte, wherein the positive electrode substrate is composed of porous Ni or a Ni alloy, and the positive electrode composite material layer comprises particles of a positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate, characterized in that... NiO is present on the surface of the particles of the positive electrode active material. The surface composition of the positive electrode active material particles satisfies 0.245≤NiO / Ni(OH)2≤1.

77.

2. The alkaline secondary battery as described in claim 1, characterized in that, The alkaline secondary battery is a nickel-metal hydride battery.

3. A method for manufacturing an alkaline secondary battery, the alkaline secondary battery comprising a positive electrode plate composed of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte, wherein the positive electrode substrate is composed of porous Ni or a Ni alloy, and the positive electrode composite material layer comprises particles of a positive electrode active material mainly composed of Ni(OH)2 filled in the positive electrode substrate, the method for manufacturing the alkaline secondary battery being characterized in that… With Ni(OH)2 filled in the cathode substrate, the temperature T [°C], humidity M [%], and time t [h] are controlled to promote the growth of NiO generated from the cathode substrate by air-based oxidation until it reaches the surface of the cathode active material particles inside the pores, wherein the surface composition of the cathode active material particles satisfies 0.245 ≤ NiO / Ni(OH)2 ≤ 1.

77.

4. The method for manufacturing an alkaline secondary battery as described in claim 3, characterized in that, The temperature T ≤ 35°C and the humidity M ≤ 90%.

5. The method for manufacturing an alkaline secondary battery as described in claim 3 or 4, characterized in that, When the positive electrode capacity lifetime [%] of an alkaline secondary battery in which there is no NiO on the surface of the positive electrode active material particles is 100 [%], the value of NiO / Ni(OH)2 is adjusted so that the positive electrode capacity lifetime [%] is within the set threshold.

6. The method for manufacturing an alkaline secondary battery as described in claim 3, characterized in that, When the internal resistance of an alkaline secondary battery is 100% in which there is no NiO on the surface of the positive electrode active material particles, the value of NiO / Ni(OH)2 is adjusted so that the internal resistance is within the set threshold.

7. The method for manufacturing an alkaline secondary battery as described in claim 3, characterized in that, The alkaline secondary battery comprises a positive electrode plate consisting of a positive electrode substrate and a positive electrode composite material layer, and an alkaline electrolyte. The positive electrode substrate is made of porous Ni or a Ni alloy, and the positive electrode composite material layer contains particles of positive electrode active material, mainly Ni(OH)2, filled in the positive electrode substrate. The positive electrode plate of an alkaline secondary battery is constructed as follows: In a state where Ni(OH)₂ is filled in the positive electrode substrate, NiO generated from the positive electrode substrate through air-based oxidation is promoted until it reaches the surface of the particles of the positive electrode active material inside the pores. In this positive electrode plate, When adding a[g] of the alkaline electrolyte to the positive electrode plate of an alkaline secondary battery, let b[g] be the amount of electrolyte that permeates into and is absorbed by the positive electrode plate, and c[g] be the amount of electrolyte that permeates into the positive electrode plate and flows out to the bottom. Then, the permeability [%] = c[g] / a[g]. The NiO / Ni(OH)2 content on the particle surface of the positive electrode active material is adjusted according to the principle that the permeability is ≥40%.

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