lead-acid batteries

Abstract

The present invention provides a lead-acid battery that can suppress PCL (polycrystalline chloride) when phosphorus is added to the electrolyte. [Solution] A liquid lead-acid battery 1 comprising a positive electrode plate 3, a negative electrode plate 2, an electrolyte, and a separator 4 interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode current collector and a positive electrode material, and at least the electrolyte and the positive electrode material contain phosphorus, and the value obtained by dividing the sum of the amount of phosphorus (mmol) contained in the electrolyte and the amount of phosphorus (mmol) contained in the positive electrode material by the volume (L) of the electrolyte is 8 mmol / L to 100 mmol / L, the phosphorus contained in the electrolyte exists as anions derived from phosphoric acid, and the positive electrode material contains antimony, the antimony content of the positive electrode material is 1 μmol / g to 15 μmol / g.

Description

[Technical Field]

[0001] This invention relates to a lead-acid battery. [Background technology]

[0002] Patent Document 1 describes a liquid lead-acid battery having a configuration in which a group of electrode plates, each consisting of a negative electrode plate filled with a negative electrode active material on a negative electrode current collector and a positive electrode plate filled with a positive electrode current collector, is stacked with a separator in between, and the group of electrode plates is housed in a battery case together with an electrolyte, wherein charging is performed intermittently and high-rate discharge to a load is performed in a partially charged state, wherein a carbonaceous conductive material is added to the negative electrode active material, and the unit electrode plate group volume in the positive electrode plate is [cm³ 3 Total surface area of ​​positive electrode plate per unit [m²] 2 ] is 2.6~3.9m 2 / cm 3 The proposed lead-acid battery has a compound selected from aluminum sulfate, a cationic surfactant, and phosphoric acid added to the electrolyte.

[0003] Patent Document 2 proposes a sealed lead-acid battery equipped with a gel-like electrolyte, characterized in that a mat-like body with a thickness of 0.5 mm or more, mainly composed of glass long fibers or synthetic resin fibers with a diameter of 10 μm or more and a diameter of 25 μm or less, and a sheet-like porous plate with a thickness of less than 0.5 mm, having a maximum pore diameter of 50 μm or less, an average pore diameter of 2 μm or more, and a silica content of 15% by mass or less, are brought into contact with each other or integrated to form a separator; a gel-like electrolyte consisting of a small amount of soluble sulfate, phosphoric acid containing 0.75% by mass or more, preferably 1.0% by mass or more and 3.0% by mass, and silica fine particles of less than 10% by mass, is disposed in at least the pores of the separator and most of the cell space around the electrode plate group, the electrode plate group is made up of positive and negative plates stacked alternately via a separator, and the positive plate is pressed against the mat-like body of the separator. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-139235 [Patent Document 2] Japanese Patent Publication No. 2003-36831 [Overview of the initiative] [Problems that the invention aims to solve]

[0005] With the advent of vehicles equipped with Idle Stop-Start (ISS) control (also known as Start-Stop control or Idle Reduction control) and OTA (Over The Air) technology, the load on lead-acid batteries is increasing. Repeated charging and discharging of lead-acid batteries can cause the positive electrode material to soften and detach, making it necessary to improve the durability of the positive electrode material.

[0006] Adding phosphorus (P) to the electrolyte is effective in suppressing the softening and detachment of the positive electrode material and inhibiting the accumulation of lead sulfate, thereby improving charge acceptance.

[0007] However, repeated deep charging and discharging of lead-acid batteries causes phosphorus to initially segregate between the positive electrode current collector and the positive electrode material, leading to an initial capacity decrease known as PCL (Premature Capacity Loss). [Means for solving the problem]

[0008] One aspect of the present invention relates to a liquid lead-acid battery comprising a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate includes a positive electrode current collector and a positive electrode material, and at least the electrolyte and the positive electrode material contain phosphorus, and the value obtained by dividing the sum of the amount of phosphorus (mmol) contained in the electrolyte and the amount of phosphorus (mmol) contained in the positive electrode material by the volume (L) of the electrolyte is 8 mmol / L or more and 100 mmol / L or less, and the positive electrode material contains antimony, and the antimony content in the positive electrode material is 1 μmol / g or more and 15 μmol / g or less.

Advantages of the Invention

[0009] According to the lead-acid battery of the present invention, PCL can be suppressed when phosphorus is added to the electrolyte.

Brief Description of the Drawings

[0010] [Figure 1] It is a partially cut-away perspective view showing the appearance and internal structure of a lead-acid battery according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present disclosure can be obtained. In this specification, the description "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "not less than numerical value A and not more than numerical value B". In the following description, when the lower limit and upper limit of a numerical value regarding a specific physical property or condition are exemplified, any combination of any of the exemplified lower limits and any of the exemplified upper limits can be made as long as the lower limit is not more than the upper limit. When a plurality of materials are exemplified, one of them may be selected and used alone, or two or more of them may be used in combination.

[0012] In addition, the present disclosure includes combinations of matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims. That is, as long as no technical contradiction occurs, matters described in two or more claims arbitrarily selected from a plurality of claims described in the appended claims can be combined.

[0013] A lead-acid battery includes a positive electrode plate, a negative electrode plate, a separator interposed between the positive electrode plate and the negative electrode plate, and an electrolyte. The electrolyte contains sulfuric acid. Charging and discharging proceed by the movement of sulfate ions between the positive electrode plate, the negative electrode plate, and the electrolyte. During discharging, sulfate ions move to the positive electrode plate and the negative electrode plate. During charging, sulfate ions move from the positive electrode plate and the negative electrode plate into the electrolyte.

[0014] The positive electrode plate, the negative electrode plate, and the separator constitute an electrode group. The electrode group and the electrolyte together constitute a cell. One electrode group constitutes one cell. A lead-acid battery includes one or more cells by including one or more electrode groups. There is no particular limitation on the number of positive electrode plates and negative electrode plates included in one electrode group. The electrode group included in the lead-acid battery according to the present disclosure includes, for example, a total of 12 or more positive electrode plates and negative electrode plates. The plurality of electrode groups are usually housed in respective individual cell chambers and connected in series with each other.

[0015] The positive electrode plate includes a positive electrode current collector and a positive electrode electrode material. The positive electrode electrode material includes, as a positive electrode active material that exhibits capacitance by an oxidation-reduction reaction, at least lead dioxide during charging and at least lead sulfate during discharging.

[0016] The negative electrode plate includes a negative electrode current collector and a negative electrode electrode material. The negative electrode electrode material includes, as a negative electrode active material that exhibits capacitance by an oxidation-reduction reaction, at least lead during charging and at least lead sulfate during discharging.

[0017] (1) A lead-acid battery according to an embodiment of the present disclosure includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode electrode material, at least the electrolyte and the positive electrode electrode material contain phosphorus, and a value obtained by dividing a total of an amount (mmol) of the phosphorus contained in the electrolyte and an amount (mmol) of the phosphorus contained in the positive electrode electrode material by a volume (L) of the electrolyte is 8 mmol / L to 100 mmol / L, the positive electrode electrode material contains antimony, and a content rate of the antimony contained in the positive electrode electrode material is 1 μmol / g to 15 μmol / g, relating to a wet (vent type) lead-acid battery.

[0018] The lead-acid battery described in (1) above contains a predetermined amount of phosphorus in the electrolyte and positive electrode material, which has the effect of suppressing softening and detachment of the positive electrode material. In the positive electrode material of a lead-acid battery in its initial stages of use, the active material particles are fine and elongated, so the particles are well intertwined with each other. On the other hand, as charging and discharging are repeated, the active material particles change into rounded, coarse particles. As a result, it becomes more difficult for the particles to come into contact with each other, and it is thought that the positive electrode material softens. In contrast, phosphorus suppresses the change in particle shape due to repeated charging and discharging by adsorbing onto the positive electrode. In addition, phosphorus also has the effect of making the lead sulfate produced during discharge finer, thereby improving the charge acceptance.

[0019] On the other hand, even in newly used lead-acid batteries, repeated deep charging and discharging causes phosphorus to segregate on the surface of the positive electrode current collector, inhibiting bonding between the positive electrode current collector and the positive electrode material. As a result, sulfate ions can easily penetrate between the positive electrode current collector and the positive electrode material, and a layer of lead sulfate forms on the surface of the positive electrode current collector during discharge, causing PCL (initial capacity degradation).

[0020] In contrast, when the positive electrode material contains antimony, and the antimony content in the positive electrode material is between 1 μmol / g and 15 μmol / g, PCL is significantly suppressed. When the positive electrode material contains antimony (Sb), antimony preferentially segregates onto the surface of the positive electrode current collector over phosphorus. As a result, segregation of phosphorus and lead sulfate onto the surface of the positive electrode current collector is suppressed, and PCL is reduced.

[0021] On the other hand, antimony does not hinder the bonding between the positive electrode current collector and the positive electrode material. Therefore, even if antimony segregates on the surface of the positive electrode current collector, PCL will not occur.

[0022] However, if the positive electrode material contains antimony, metallic lead is likely to remain during the maturation process of the positive electrode plate, which can reduce the chemical properties of the positive electrode plate. When the chemical properties decrease, the bonding force between the positive electrode materials weakens, making the positive electrode materials more prone to detachment.

[0023] In contrast, when the positive electrode material contains phosphorus, the phosphorus improves the bonding strength between the positive electrode materials. In other words, phosphorus and antimony have complementary effects that compensate for each other's disadvantages.

[0024] The phosphorus contained in the electrolyte may exist as anions derived from phosphoric acid. Anions derived from phosphoric acid are readily soluble in the electrolyte and are chemically stable. Anions derived from phosphoric acid may be monovalent to trivalent. Anions derived from phosphoric acid may be derived from phosphoric acid (H3PO4) or from phosphates (such as Na3PO4). Phosphates may also be hydrogen phosphates. Hydrogen phosphates may be monohydrogen salts (such as Na2HPO4) or dihydrogen salts (such as NaH2PO4).

[0025] (2) In the lead-acid battery described in (1) above, the positive electrode material may contain tin (Sn), and the tin content in the positive electrode material may be 5 μmol / g or more.

[0026] The lead-acid battery described in (2) above has improved high-rate discharge performance because the specific surface area of ​​the positive electrode material is increased by the use of tin.

[0027] (3) In the lead-acid battery described in (1) or (2) above, the electrolyte may further contain metal cations. The concentration of the metal cations may be 30 mmol / L or more.

[0028] In the lead-acid battery described in (3) above, penetration short circuits are suppressed by the action of metal cations contained in the electrolyte.

[0029] (4) In the lead-acid battery described in (3) above, the metal cation may include at least one selected from the group consisting of Na, Li, and Al. When the metal cation is at least one selected from the group consisting of Na, Li, and Al, penetration short circuits are significantly suppressed.

[0030] A lead-acid battery described in any one of the above (1) to (4) is useful as a power source for applications where charging and discharging are controlled in a state of undercharge called a partially charged state (PSOC). Specific examples of power sources for applications where charging and discharging are controlled by PSOC include power sources for ISS-controlled vehicles (ISS-controlled vehicles) and power sources for auxiliary equipment. For example, a lead-acid battery used as a power source for an ISS-controlled vehicle may undergo repeated charging and discharging in PSOC. Repeated charging and discharging of a lead-acid battery in PSOC places a large load on the positive electrode plate, making it prone to softening and detachment of the positive electrode material. In other words, in lead-acid batteries where charging and discharging are controlled by PSOC, the effect of improving the durability of the positive electrode material by adding phosphorus and antimony to the positive electrode material is likely to become apparent.

[0031] In this specification, the fully charged state of a liquid lead-acid battery is defined according to the definition in JIS D5301:2019. More specifically, in a water bath at 25°C ± 2°C, the 20-hour rate current I is charged until the terminal voltage (in volts) or the electrolyte density converted to 20°C shows a constant value with three significant figures for three consecutive 15-minute intervals. 20 Twice the current 2 × I 20 (Unit: A) The fully charged state of a lead-acid battery is defined as the state in which it has been charged. Note that n-hour rate current I n This refers to a current (A) that is 1 / n of the Ah value listed for the n-hour rate rated capacity. The value listed for the rated capacity is a value in Ah (ampere-hour). The unit of the current set based on the value listed for the rated capacity is A (ampere).

[0032] A fully charged lead-acid battery is a lead-acid battery that has been charged to its full capacity after chemical formation. The timing for charging a lead-acid battery to its full capacity can be immediately after chemical formation, or after a certain amount of time has passed since formation (e.g., 720 hours or less). For example, a lead-acid battery that has been chemically formed and is in use (preferably in the early stages of use) may be charged.

[0033] In this specification, a battery in its initial use refers to a battery that has not been used for very long and has not deteriorated much (for example, a battery that has been in use for less than 720 hours, including the time elapsed since chemical preparation).

[0034] The amount of detachment due to softening of the positive electrode material can be evaluated, for example, by a charge-discharge test that repeatedly discharges and charges at a DOD (Depth of Discharge) equivalent to 10%.

[0035] The charge acceptance of a lead-acid battery can be evaluated, for example, by the amount of electricity charged after charging at a constant voltage for a certain period of time following a discharge equivalent to 50% of the DOD (Domain-of-Depth) capacity.

[0036] The presence or absence of PCL (Programmable Cycle Load) can be evaluated, for example, by the discharge capacity at the 5th cycle in a charge-discharge test that repeatedly discharges to a DOD equivalent to 100%. The presence or absence of PCL can also be evaluated using a battery that has not degraded much, having been used for less than 720 hours since chemical formation.

[0037] The lead-acid battery according to the embodiments of the present invention will be described in more detail below with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0038] The following describes examples of components of a lead-acid battery.

[0039] (Positive plate) The positive electrode plate comprises a positive electrode current collector and a positive electrode material. The positive electrode material is held by the positive electrode current collector. The positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector. Adhesive members such as conductive layers, mats, and pasting paper may be attached to the positive electrode plate. Since the adhesive members are used integrally with the positive electrode plate, they are included as components of the positive electrode plate. When the positive electrode plate includes adhesive members, the positive electrode material is the portion of the positive electrode plate excluding the positive electrode current collector and the adhesive members.

[0040] The positive electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. Processing methods may include, for example, expansion or punching. Using a grid-like current collector as the positive electrode current collector makes it easier to support the positive electrode material.

[0041] As the lead alloy used for the positive electrode current collector, Pb-Ca alloys and Pb-Ca-Sn alloys, which have excellent corrosion resistance and mechanical strength, are preferred. The positive electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0042] The positive electrode material contains a positive electrode active material that exhibits capacity through a redox reaction. The positive electrode active material includes lead dioxide, lead sulfate, etc. The positive electrode material further contains phosphorus (P) and antimony (Sb).

[0043] Phosphorus may be introduced into the lead-acid battery by dissolving at least one selected from the group consisting of phosphoric acid and phosphates in the electrolyte. In this case, anions derived from phosphoric acid are also present in the electrolyte. However, up to about 90% is adsorbed onto the positive electrode material.

[0044] The amount of phosphorus contained in the positive electrode material is controlled so that the value obtained by dividing the sum of the amount of phosphorus contained in the electrolyte (mmol) and the amount of phosphorus contained in the positive electrode material (mmol) by the volume of the electrolyte (L) (hereinafter also referred to as "P content (EP)") is between 8 mmol / L and 100 mmol / L. The P content (EP) may be controlled to be 25 mmol / L or more, or 50 mmol / L or less. The P content (EP) may be controlled to be between 25 mmol / L and 100 mmol / L, or between 25 mmol / L and 50 mmol / L.

[0045] Antimony can be incorporated into the cathode electrode material raw material paste (cathode paste) during the manufacturing process of the cathode plate in the form of an antimony compound. Examples of antimony compounds that can be used include diantimony trioxide (Sb2O3), diantimony tetroxide (Sb2O4), and diantimony pentoxide (Sb2O5).

[0046] The antimony content in the positive electrode material is 1 μmol / g to 15 μmol / g, and may also be 5 μmol / g to 15 μmol / g.

[0047] The positive electrode material may further contain tin (Sn). Tin has the effect of increasing the specific surface area of ​​the positive electrode material. The larger the specific surface area of ​​the positive electrode material, the better the high-rate discharge performance.

[0048] Tin can be incorporated in the form of a tin compound into the raw material paste (positive electrode paste) of the positive electrode material during the manufacturing process of the positive electrode plate. Examples of tin compounds that can be used include tin oxide (SnO), tin sulfate (SnSO4), and tin dioxide (SnO2).

[0049] The tin content in the positive electrode material is, for example, 5 μmol / g or more, and may be between 5 μmol / g and 15 μmol / g.

[0050] The phosphorus, antimony, and tin content in the positive electrode material can be measured by taking samples of the positive electrode material from the positive electrode plate removed from a fully charged lead-acid battery and measuring them using ICP-AES. The samples of the positive electrode material are taken from the positive electrode plate removed from a fully charged lead-acid battery.

[0051] Specifically, a suitable amount of dry positive electrode material is taken as a sample, and its mass is measured. The positive electrode material sample is recovered from the positive electrode plate using the following procedure. First, a fully charged lead-acid battery is disassembled, and the obtained positive electrode plate is washed with water until the color of the pH test paper pressed against the surface of the positive electrode plate no longer changes, thereby removing the electrolyte from the positive electrode plate. The washed positive electrode plate is dried in a constant temperature bath at 50°C ± 2°C for 12 hours or more. After drying, if the positive electrode plate contains adhesive material, the adhesive material is removed from the positive electrode plate by peeling it off. A sample of positive electrode material for analysis is obtained by taking a sample of the positive electrode material from near the center of the top, bottom, left, and right sides when the positive electrode plate is viewed from the front.

[0052] Next, the entire sample is dissolved in a mixed aqueous solution containing tartaric acid, nitric acid, and hydrogen peroxide. The solution obtained by total dissolution is diluted to a fixed volume with deionized water as needed, and then the emission intensity of phosphorus, antimony, or tin in the solution is measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) with an ICP emission spectrometer. The mass of phosphorus, antimony, or tin contained in the solution is then determined using a pre-prepared calibration curve. The ratio of the obtained mass of phosphorus, antimony, or tin to the mass of the sample of positive electrode material subjected to analysis is determined as the phosphorus, antimony, or tin content. For example, the ICPS-8000 manufactured by Shimadzu Corporation is used as an ICP emission spectrometer.

[0053] The amount of phosphorus (mmol) contained in the positive electrode material can be calculated from the sample mass, the measured value, and the total mass of the positive electrode material.

[0054] Positive electrodes are obtained by chemically converting unconverted positive electrodes. Unconverted positive electrodes are obtained by filling a positive electrode current collector with positive electrode paste, allowing it to mature, and drying. Positive electrode paste is prepared, for example, by kneading a mixture containing lead powder, antimony compounds, tin compounds, water, and sulfuric acid. Such positive electrodes are also called paste-type positive electrodes.

[0055] Chemical treatment may be carried out by immersing the electrode plate group, including the untreated positive electrode plate, in the sulfuric acid-containing electrolyte in the lead-acid battery case and charging the electrode plate group. Chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group.

[0056] (Negative electrode plate) The negative electrode plate comprises a negative electrode current collector and a negative electrode material. The negative electrode material is held by the negative electrode current collector. The negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector. Note that adhesive members such as conductive layers, mats, and pasting paper may be attached to the negative electrode plate. The adhesive members are included as components of the negative electrode plate. When the negative electrode plate includes adhesive members, the negative electrode material is the portion of the negative electrode plate excluding the negative electrode current collector and the adhesive members.

[0057] The negative electrode current collector may be formed by casting lead (Pb) or a lead alloy, or by processing a lead or lead alloy sheet. The processing method may be expansion or punching. Using a grid-like current collector as the negative electrode current collector makes it easier to support the negative electrode material.

[0058] The lead alloy used for the negative electrode current collector may be any of the following: a Pb-Sb alloy, a Pb-Ca alloy, or a Pb-Ca-Sn alloy. The lead alloy used for the negative electrode current collector may also contain at least one additive element selected from the group consisting of Ba, Ag, Al, Bi, As, Se, Cu, etc. The negative electrode current collector may have metal layers of different compositions, and the metal layers may be one layer or multiple layers.

[0059] The negative electrode material contains a negative electrode active material that exhibits capacity through an oxidation-reduction reaction. The negative electrode active material includes lead, lead sulfate, etc. The negative electrode material may contain other additives as needed. The additives may include organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0060] Examples of organic shrinkage inhibitors include lignin, lignin sulfonic acid, and synthetic organic shrinkage inhibitors. Synthetic organic shrinkage inhibitors may be, for example, formaldehyde condensates of phenolic compounds. Organic shrinkage inhibitors may be used individually or in combination of two or more. The content of organic shrinkage inhibitors in the negative electrode material is, for example, 0.01% by mass or more and 1% by mass or less.

[0061] As carbonaceous materials, carbon black, artificial graphite, natural graphite, hard carbon, soft carbon, etc., can be used. One type of carbonaceous material may be used alone, or two or more types may be used in combination. The carbonaceous material content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0062] The barium sulfate content in the negative electrode material is, for example, 0.1% by mass or more and 3% by mass or less.

[0063] The negative electrode plate is obtained by chemically converting an unconverted negative electrode plate. The unconverted negative electrode plate is obtained by filling a negative electrode current collector with negative electrode paste, allowing it to mature, and drying. The negative electrode paste is prepared by kneading a mixture containing lead powder, water, and sulfuric acid. The negative electrode paste may optionally contain organic shrinkage inhibitors, carbonaceous materials, barium sulfate, etc.

[0064] The chemical treatment may be carried out by immersing the electrode plate group, including the untreated negative electrode plate, in an electrolyte containing sulfuric acid in the lead-acid battery case, thereby charging the electrode plate group. The chemical treatment may also be carried out before the assembly of the lead-acid battery or the electrode plate group. The charged negative electrode active material contains spongy lead.

[0065] (Separator) Lead-acid batteries typically have a separator between the negative and positive electrodes. A microporous membrane can be used as the separator.

[0066] A microporous membrane is a porous sheet mainly composed of materials other than fibrous components. Preferably, the amount of materials other than fibrous components is, for example, 60% by mass or more. A microporous membrane can be obtained, for example, by extruding a resin composition containing a pore-forming agent into a sheet, and then removing the pore-forming agent to form pores. A microporous membrane is preferably composed of an acid-resistant polymer component. Polyolefins are preferred as the polymer component.

[0067] The thickness of the separator placed between the negative electrode plate and the positive electrode plate should be selected according to the distance between the two plates.

[0068] (electrolyte) The electrolyte is an aqueous solution containing sulfuric acid. The electrolyte contains phosphorus as an anion derived from phosphoric acid. The electrolyte may optionally contain cations (e.g., metal cations) and / or anions not derived from sulfuric acid.

[0069] When the electrolyte contains metal cations, the concentration of the metal cations is preferably, for example, 30 mmol / L or higher. This provides an effect of suppressing osmotic short circuits. The mechanism is that the presence of metal cations causes lead ions (Pb) to penetrate. 2+ This is because the solubility of lead decreases, suppressing dendrite growth caused by the precipitation of dissolved lead.

[0070] Qualitative analysis of anions derived from phosphoric acid in the electrolyte and quantitative analysis of phosphorus can be performed by LC-MS.

[0071] As the metal cation, at least one ion selected from the group consisting of Na, Li, and Al is preferred.

[0072] The concentration of metal cations in the electrolyte is determined by analyzing the electrolyte taken from a fully charged lead-acid battery using ICP-AES. More specifically, using an ICP emission spectrometer, the types of metal cations in the electrolyte are identified, and the emission intensity of the metal cations is measured. From the measured value of this emission photometry and the calibration curve prepared in advance, the concentration of the metal cations contained in the electrolyte is determined. As the ICP emission spectrometer, ICPS-8000 manufactured by Shimadzu Corporation is used.

[0073] The density at 20°C of the electrolyte in a fully charged lead-acid battery is, for example, 1.20 g / cm 3 or more, and may be 1.25 g / cm 3 or more. The density at 20°C of the electrolyte is 1.35 g / cm 3 or less, and preferably 1.32 g / cm 3 or less. The density at 20°C of the electrolyte in a fully charged lead-acid battery is, for example, 1.20 g / cm 3 ~1.35 g / cm 3 and may be 1.25 g / cm 3 ~1.32 g / cm 3

[0074] The P content rate (EP) is the value obtained by dividing the total of the amount of phosphorus (mmol) contained in the positive electrode material determined by the method described above and the amount of phosphorus (mmol) contained in the electrolyte by the volume (L) of the electrolyte (P content rate (EP) = ((amount of phosphorus (mmol) contained in the positive electrode material) + amount of phosphorus (mmol) in the electrolyte)) / volume (L) of the electrolyte).

[0075] The mass of the electrolyte can be calculated from the mass of the cell containing the electrolyte and the mass of the cell from which the electrolyte has been removed by washing and drying. The volume (L) of the electrolyte can be calculated from the mass of the electrolyte and the density (g / cm 3 ) of the electrolyte.

[0076] (Example of lead-acid battery) ​Figure 1 shows the external appearance and part of the internal structure of a lead-acid battery according to one embodiment. The lead-acid battery 1 comprises a battery case 12 that houses an electrode plate group 11 and an electrolyte (not shown). The inside of the battery case 12 is divided into a number of cell chambers 14 by a partition wall 13. Each cell chamber 14 houses one electrode plate group 11. The opening of the battery case 12 is closed with a lid 15 equipped with a negative electrode terminal 16 and a positive electrode terminal 17. The lid 15 is provided with a vent plug 18 for each cell chamber. When replenishing water, the vent plug 18 is removed and the water is replenished. The vent plug 18 may also have a function of discharging gas generated in the cell chamber 14 to the outside of the battery.

[0077] Each electrode plate group 11 is constructed by stacking multiple negative electrode plates 2 and positive electrode plates 3 via separators 4. Here, a bag-shaped separator 4 that houses the negative electrode plates 2 is shown, but the shape of the separator is not particularly limited. In the cell chamber 14 located at one end of the battery case 12, a negative electrode strap 6 connecting multiple negative electrode plates 2 in parallel is connected to a through connector 8, and a positive electrode strap 5 connecting multiple positive electrode plates 3 in parallel is connected to a positive electrode column 7. The positive electrode column 7 is connected to a positive electrode terminal 17 on the outside of the lid 15. In the cell chamber 14 located at the other end of the battery case 12, a negative electrode column 9 is connected to the negative electrode strap 6, and a through connector 8 is connected to the positive electrode strap 5. The negative electrode column 9 is connected to a negative electrode terminal 16 on the outside of the lid 15. Each through connector 8 passes through a through hole provided in the partition wall 13, connecting the electrode plate groups 11 of adjacent cell chambers 14 in series.

[0078] Note that Figure 1 is merely one example of a liquid-type lead-acid battery, and the structure of the lead-acid battery relating to this disclosure is not limited to the example shown.

[0079] The following describes the evaluation method for lead-acid batteries. For the evaluation, a lead-acid battery (nominal voltage 12V) with six cells (connected in series), each consisting of six positive electrodes and six negative electrodes, will be used. However, the evaluation battery is not limited to a 12V battery; a battery other than 12V (6 cells) may be used. In that case, the test voltage may be the product of 12 / 6 = 2 (V) and the number of cells under the following conditions.

[0080] (Amount of detached positive electrode material) The evaluation is performed by a charge-discharge test that involves repeated discharge and charging cycles equivalent to 10% DOD. Specifically, a fully charged lead-acid battery with a nominal voltage of 12V is subjected to 800 charge-discharge cycles under the following conditions. Afterwards, the positive electrode plate is washed with water, dried, and its mass is measured. The difference between the initial design mass of the positive electrode plate and the mass of the positive electrode plate after washing and drying is defined as the "amount of plate loss." Discharge: 10×I 20 (Unit: A), 12 min Charging: 10×I 20 (Unit: A), 12.6 min Temperature: Aquarium 30±1℃

[0081] (Charge acceptance) The evaluation is performed by a charge-discharge test involving repeated discharges equivalent to 50% DOD. Specifically, a fully charged lead-acid battery with a nominal voltage of 12V is tested under the following conditions, and the amount of charge collected over 10 minutes in (c) is defined as the charge acceptability. (a) 2 × I 20 Discharge for 5.0 hours at (unit: A) (temperature in the water bath: 25±1 ℃) (b) Rest for 12 hours (temperature in the air chamber: 0±1℃) (c) Charge at 14.4V (2.4V / cell) for 10 minutes with a maximum current of 50A (temperature in the chamber should be 0±1℃).

[0082] (Presence or absence of PCL) The evaluation is performed by a charge-discharge test that involves repeated discharges equivalent to 100% DOD. Specifically, for a fully charged lead-acid battery with a nominal voltage of 12V, the charge-discharge cycle is repeated 5 times under the following conditions, and the presence or absence of PCL formation is determined from the discharge capacity after the 5th cycle. Discharge:I 20 (Unit: A), FV = 10.5V (1.75V / cell) Charging: 2 x I 20 (Unit: A), Charge to 130% of discharge amount Temperature: Aquarium 25±1℃

[0083] (High-rate discharge performance) For a fully charged lead-acid battery with a nominal voltage of 12V, the discharge current is 60 × I 20 At point A, discharge the battery at 30±1℃ until the terminal voltage reaches 8.4V (1.4V / cell), and determine the discharge time. A longer discharge duration indicates superior high-rate discharge performance.

[0084] (Penetration short-circuit area) For a lead-acid battery with a nominal voltage of 12V, charge and discharge will be performed in a water bath at 25°C ± 1°C under the following conditions. Specifically, steps (A) to (C) below will be repeated five times, followed by step (D). (A)I 20 Discharge to 6.0V with a constant current of (A). (B) Connect a 10Ω resistor to the battery and leave it for 28 days. (C) Charge for 30 minutes at a constant voltage of 14.4V (2.4V / cell) with an upper limit current of 50A. (D)I 20 Charge for 27 hours with a constant current of (A).

[0085] After the charging and discharging process described above, the battery is disassembled, the separators are removed, and the area of ​​the lead infiltration traces (in other words, lead marks) is determined. The area of ​​the infiltration traces is determined by image processing of a photograph of the separator. In lead-acid batteries with multiple series-connected electrode plates, the area of ​​the infiltration traces is determined for all separators in one of the outermost electrode plate groups and one of the electrode plate groups located near the center, and the average value per separator is calculated.

[0086] [Examples] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0087] Lead-acid batteries E1-E12 and R1-R19 (1) Fabrication of the negative electrode plate A negative electrode paste is prepared by mixing lead oxide, carbon black, barium sulfate, lignin, water, and sulfuric acid. The negative electrode paste is filled into the mesh of an expanded grid made of antimony-free Pb-Ca-Sn alloy, which serves as the negative electrode current collector, and then aged and dried to obtain an unformed negative electrode plate. The amounts of carbon black, barium sulfate, and lignin are adjusted so that they are 0.3 mass%, 0.5 mass%, and 0.1 mass%, respectively, when measured in the fully charged, already formed state.

[0088] (2) Fabrication of the positive electrode plate A positive electrode paste is prepared by mixing lead oxide, antimony trioxide (Sb2O3), water, and sulfuric acid. At this time, the formulation is adjusted so that the antimony content of the positive electrode material, as measured by the procedure described above, is the value shown in Table 1. The positive electrode paste is filled into the mesh of an expanded grid made of antimony-free Pb-Ca-Sn alloy, which is the positive electrode current collector, and then aged and dried to obtain an unformed positive electrode plate.

[0089] (3) Separator Prepare a bag-shaped separator by folding a polyethylene microporous membrane in half.

[0090] (4) Preparation of electrolyte The electrolyte is prepared by dissolving phosphoric acid (H3PO4) in an aqueous sulfuric acid solution so that the sum of the amount of phosphorus (mmol) in the electrolyte and the amount of phosphorus (mmol) in the positive electrode material, divided by the volume of the electrolyte (L), (P content (EP)) is as shown in Table 1. After chemical conversion, the density of the electrolyte is 1.28 ± 0.01 g / cm³. 3 Prepare it as follows.

[0091] (5) Manufacturing of lead-acid batteries Untreated negative electrode plates are placed in a bag-shaped separator, and five untreated negative electrode plates and four untreated positive electrode plates are stacked alternately to form an electrode plate group. The tabs of the positive electrode plates and the tabs of the negative electrode plates are welded to the positive and negative electrode straps, respectively, using the cast-on-strap (COS) method. The electrode plate group is inserted into a polypropylene battery case, electrolyte is poured in, and the electrode plate group is treated within the case to assemble a liquid lead-acid battery with a nominal voltage of 12V and a rated 20-hour rate capacity of 60Ah. Six electrode plate groups are connected in series within the battery case.

[0092] (6) Evaluation The fabricated lead-acid battery was fully charged using the procedure described above, and the amount of positive electrode material shedding, charge acceptance, and presence or absence of PCL formation (capacity after 5 cycles) were evaluated using the method described above. The results are shown in Table 1. Each evaluation is expressed as a relative value (%) with the result of lead-acid battery R1 set to 100%.

[0093] [Table 1]

[0094] From batteries R1 to R7, it was found that when antimony is not added to the positive electrode material and phosphoric acid is added to the electrolyte, the amount of delamination of the positive electrode material is suppressed and the charge acceptance is improved when the phosphorus content (EP) is in the range of 8 to 100 mmol / L, but the capacity after 5 cycles decreases.

[0095] From batteries R8 to R13, it was found that when phosphoric acid was not added to the electrolyte and antimony was added to the positive electrode material, the amount of delamination of the positive electrode material was suppressed and there was almost no decrease in capacity after 5 cycles when the antimony content was in the range of 1 to 15 μmol / g, but no improvement in charge acceptance was observed. Similar results were obtained when only 5 mmol / L of phosphoric acid was added to the electrolyte and antimony was added to the positive electrode material (batteries R14 to R16). However, at an antimony content of 20 μmol / g, the capacity after 5 cycles decreased due to poor chemical conversion.

[0096] On the other hand, from batteries E1 to E12, it can be seen that when the phosphorus content (EP) is in the range of 8 to 100 mmol / L and the antimony content in the positive electrode material is in the range of 1 to 15 μmol / g, the shedding of the positive electrode material is significantly suppressed, the decrease in capacity after 5 cycles is also suppressed, and an improvement in charge acceptance is observed.

[0097] From batteries R17 to R19, it can be seen that adding an excessive amount of phosphoric acid to the electrolyte significantly reduces the charge acceptance.

[0098] 《Lead acid battery E13~E16》 When preparing the positive electrode paste, the positive electrode plate and the lead-acid battery equipped therewith are fabricated and evaluated in the same manner as battery E11, except that tin sulfate (SnSO4) is added so that the tin content of the positive electrode material measured by the procedure described above is as shown in Table 2. The results are shown in Table 2. In addition, the high-rate discharge performance is evaluated using the method described above. Each evaluation is shown as a relative value (%) with the result of lead-acid battery R1 set to 100%.

[0099] [Table 2]

[0100] Table 2 shows that adding more tin to the positive electrode material improves the high-rate discharge performance.

[0101] 《Lead acid battery E17~E25》 Except for blending metal cations as sulfates to achieve the values ​​shown in Table 3, the electrolyte and a lead-acid battery containing it were prepared and evaluated in the same manner as for battery E11. The results are shown in Table 3. The penetration short-circuit area was also evaluated using the method described above. Each evaluation is shown as a relative value (%) with the result of lead-acid battery R1 set to 100%.

[0102] [Table 3]

[0103] Table 3 shows that when the cation concentration in the electrolyte is 30 mmol / L or higher, a significant effect in suppressing osmotic short circuits can be obtained.

[0104] 《Lead acid battery R25~R28》 A valve-regulated lead-acid battery (VRLA) with a nominal voltage of 12V and a rated 10-hour rate capacity of 7.2Ah will be manufactured. The electrode plate assembly will consist of three positive plates and four negative plates. The positive and negative plates will be stacked alternately with a separator in between to form the electrode plate assembly. The electrode plate assembly will be housed in an ABS battery case and sealed with a lid. A fine glass mat will be used as the separator. After pouring in the electrolyte, the electrode plate assembly will undergo a chemical conversion process within the battery case to manufacture the valve-regulated lead-acid battery. The chemical conversion will bring the lead-acid battery to a fully charged state. The density of the electrolyte in a fully charged lead-acid battery at 20°C is 1.33 g / cm³. 3 That is the case.

[0105] In battery R25, the phosphorus content (EP) is set to 0 mmol / L, and the antimony content in the positive electrode material is set to 0 μmol / g. For battery R26, the phosphorus content (EP) is set to 50 mmol / L. In battery R27, the antimony content in the positive electrode material is set to 5 μmol / g. In battery R28, the phosphorus content (EP) is set to 50 mmol / L, and the antimony content in the positive electrode material is set to 5 μmol / g. Other than the above, the configuration is the same.

[0106] Similar to the case of liquid lead-acid batteries, the following charge-discharge cycle equivalent to 10% DOD was repeated 800 times, and the amount of positive electrode material shedding was evaluated in the same manner. The results are shown in Table 4. Each evaluation is shown as a relative value (%) with the result of lead-acid battery R25 set to 100%. Discharge: 5×I 10 (Unit: A), 12 min Charging: 5×I 10 (Unit: A), 12.6 min Temperature: Aquarium 30±1℃

[0107] [Table 4]

[0108] As shown in Table 4, there is almost no significant difference in suppression of positive electrode material detachment between the R25 battery, which does not use either phosphorus or antimony, and the R25 battery, which does not use either phosphorus or antimony. This is thought to be because, in valve-regulated lead-acid batteries, pressure is applied to the electrode group, making detachment of the positive electrode material less likely to occur in the first place. [Industrial applicability]

[0109] The lead-acid battery according to the present invention is suitable as a lead-acid battery whose charging and discharging are controlled by a PSOC, for example, as a starting power source or auxiliary lead-acid battery for vehicles controlled by an ISS, but its applications are not particularly limited. [Explanation of Symbols]

[0110] 1: Lead-acid battery, 2: Negative electrode plate, 3: Positive electrode plate, 4: Separator, 5: Positive electrode strap, 6: Negative electrode strap, 7: Positive electrode post, 8: Through connector, 9: Negative electrode post, 11: Electrode plate group, 12: Battery case, 13: Partition wall, 14: Cell chamber, 15: Cover, 16: Negative electrode terminal, 17: Positive electrode terminal, 18: Electrode cap

Claims

1. It comprises a positive electrode plate, a negative electrode plate, an electrolyte, and a separator interposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode material. At least the electrolyte and the positive electrode material contain phosphorus, The value obtained by dividing the sum of the amount of phosphorus (mol) contained in the electrolyte and the amount of phosphorus (mol) contained in the positive electrode material by the volume (L) of the electrolyte is 8 mmol / L or more and 100 mmol / L or less. The positive electrode material contains antimony, A liquid lead-acid battery in which the antimony content in the positive electrode material is 1 μmol / g or more and 15 μmol / g or less.

2. The positive electrode material contains tin, The liquid lead-acid battery according to claim 1, wherein the tin content in the positive electrode material is 5 μmol / g or more.

3. The electrolyte further contains a metal cation. The liquid lead-acid battery according to claim 1, wherein the concentration of the metal cation is 30 mmol / L or more.

4. The liquid lead-acid battery according to claim 3, wherein the metal cation is at least one selected from the group consisting of Na, Li, and Al.

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