JP2019204790A - Control valve type lead-acid battery - Google Patents

Abstract

To provide a control valve type lead-acid battery with a long life, which is suppressed in corrosion of an ear of a negative electrode collector.SOLUTION: A control valve type lead-acid battery includes a negative electrode collector or a negative electrode ear which comprises a Pb-Ca-Sn alloy containing 0.07-0.12 mass% of Ca and 0.75 mass% or less of Sn with respect to the total mass of the alloy or a Pb-Ca alloy containing 0.07-0.12 mass% of Ca with respect to the total mass of the alloy, the ratio of the mass of a positive electrode material with respect to the mass of a negative electrode material being 1.27-1.35 or 1.47 or more.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a control valve type lead acid battery, and more particularly to a control valve type lead acid battery in which corrosion of an ear of a negative electrode current collector is suppressed.

  For lead-acid batteries, an open-type liquid battery constructed by injecting an electrolyte into a battery case in which an electrode plate group is inserted, and a fine glass mat separator (retainer mat) inserted between a positive electrode plate and a negative electrode plate In other words, there is a control valve type battery using a so-called oxygen cycle, in which an electrolytic solution is retained and oxygen gas generated at the positive electrode is reduced to water on the negative electrode active material.

  Liquid batteries lose water in the electrolyte due to water electrolysis and spontaneous evaporation that occur during charging, and it is necessary to replenish purified water as needed. Since it can be made free, its use has been progressing recently for stationary use and in-vehicle use.

  In the control valve type lead-acid battery, since the weld of the negative electrode current collector and the strap is exposed from the electrolytic solution, the lead-acid battery is placed in a noble state from the equilibrium potential of lead even during charging. For this reason, the negative electrode current collector has a problem that corrosion occurs at the ears and straps due to sulfuric acid that scoops up the ears and straps and oxygen generated from the positive electrode, resulting in frequent fracture at the weld interface. For the purpose of improving, various studies have been made on the alloy composition of the negative electrode current collector.

  Patent Document 1 states that “lead (Pb) —Ca—Sn system containing 0.025 to 0.065% by mass of calcium (Ca) and 0.25 to 1.0% by mass of tin (Sn) in the negative electrode lattice. A sealed lead-acid battery using pure lead or a Pb-Sn alloy containing 1.3 mass% or less of Sn as an additional lead for forming a strap for connecting an electrode plate ear using an alloy (Claim 1): "In the case where the amount of Ca in the negative electrode lattice is 0.020 to 0.065 mass%, corrosion occurs in the negative electrode strap (near the welded portion) even after the overcharge test. Was hardly recognized "(0044).

  Patent Document 2 discloses a “lead storage battery characterized in that the ears of the electrode plate lattice made of a lead-tin-calcium alloy are connected to each other by a shelf made of a lead-tin-selenium alloy” (claim) Regarding 1), it is stated that “an expanded lattice obtained by subjecting a lead alloy sheet made of lead-0.5% by weight tin-0.08% by weight calcium alloy to an expanded process as the negative electrode lattice” was used (0012). Has been.

Patent Document 3 states that “the density of the negative electrode active material is 3.5 to 4.0 g / cm ³ and the mass ratio of the negative electrode active material to the positive electrode active material is (negative / positive) is 0.5 to 0. The control valve type lead-acid battery characterized in that it is .8 (Claim 1), “the mass ratio (negative / positive) of the negative electrode active material and the positive electrode active material is defined as small to 0.5 to 0.8” Therefore, the floating charging current in standby use is reduced, corrosion of the positive electrode grid is prevented, and the life is long, and the density of the negative electrode active material is defined as small as 3.5 to 4.0 g / cm ³ , so that the negative electrode active material Therefore, even if the amount of the negative electrode active material is reduced with respect to the amount of the positive electrode active material, the low-temperature high-rate discharge characteristics are maintained at the same level as the conventional product ”(0007).
When the mass ratio (negative / positive) 0.5 to 0.8 of the negative electrode active material and the positive electrode active material is converted into the ratio (positive / negative) of the mass of the positive electrode active material to the mass of the negative electrode active material, 1.25 to 2.0.

Patent Document 4 states that “the total amount of active material (P) held in the formed positive electrode plate and the total amount of active material (N) held in the formed negative electrode plate”. The mass ratio N / P has a relationship of 1.0 <N / P ≦ 1.2, and the porosity of the active material of the positive electrode plate in the formed state is in the range of 45 to 50%. The control valve-type lead-acid storage battery is as follows. (Claim 1) “When the relationship of mass ratio N / P is in the range of 1.0 <N / P ≦ 1.2, Even if hard-to-reduced lead sulfate accumulates in the negative electrode plate when used for a long time, the negative electrode plate has enough active material necessary to participate in the charge / discharge reaction with the positive electrode plate. The life of the storage battery can be extended, and the porosity of the active material held on the positive electrode plate is 45 to 50%. It is possible to suppress the deterioration and mudification of the active material associated with the charge / discharge cycle having a deep discharge depth, and to realize a long-life lead-acid battery ”(0007). .
When this N / P is converted into the ratio (P / N) of the mass of the positive electrode active material to the mass of the negative electrode active material, it is 0.83 to 1.0.

JP 2002-175798 A JP-A-8-339794 JP 2006-49025 A JP 2014-207198 A

In conventional control valve type lead-acid batteries, various alloy compositions of negative electrode current collectors have been studied for the purpose of improving the corrosion resistance of the negative electrode current collector ears, and certain results have been achieved. However, even if an alloy composition with high corrosion resistance is selected, there is a problem that some batteries used in a high temperature environment have a short float life and do not reach the target value.
Moreover, in the control valve type lead-acid battery, the mass ratio between the positive electrode active material and the negative electrode active material can be regulated by preventing the deterioration of the positive electrode plate (see Patent Document 3 (0007)) or by reducing the negative electrode capacity due to the accumulation of lead sulfate. Conventionally, for the purpose of countermeasures (see Patent Document 4 (0007)) and the like. However, the prior art that refers to the relationship between the above-described mass ratio and the corrosion resistance of the negative electrode current collector ear could not be found.

  An object of the present invention is to provide a control valve type lead storage battery in which corrosion of an ear of a negative electrode current collector is suppressed and the life is long.

In order to achieve the above object, the present invention employs the following means.
(1) Pb-Ca-Sn alloy containing 0.07 mass% or more and 0.12 mass% or less of Ca, or Sn0.75 mass% or less with respect to the total mass of the alloy, or Ca0 with respect to the total mass of the alloy A negative electrode current collector made of a Pb—Ca-based alloy containing 0.07% by mass or more and 0.12% by mass or less, and the ratio of the mass of the positive electrode material to the mass of the negative electrode material is 1.27 or more and 1 Control valve type lead acid battery which is .35 or less, or 1.47 or more.
(2) Pb-Ca-Sn alloy containing 0.07 mass% or more and 0.12 mass% or less of Ca, or Sn0.75 mass% or less with respect to the total mass of the alloy, or Ca0. The negative electrode ear which consists of Pb-Ca type alloy containing 07 mass% or more and 0.12 mass% or less is provided, and the ratio of the mass of positive electrode material to the mass of negative electrode material is 1.27 or more and 1.35 or less Or a valve-regulated lead-acid battery that is 1.47 or higher.

  ADVANTAGE OF THE INVENTION According to this invention, the corrosion of the ear | edge of a negative electrode collector can be suppressed, and a long-life control valve type lead acid battery can be provided.

Graph showing the relationship between the potential of the negative electrode strap and the corrosion rate of the negative electrode current collector ear The graph which shows the relationship between the positive electrode / negative electrode electrode material mass ratio and the electric potential of a negative electrode strap part Graph showing the relationship between the alloy composition of the negative electrode current collector, the float life years, and the negative electrode corrosion amount (positive electrode / negative electrode material mass ratio = 1.27) Graph showing the relationship between the alloy composition of the negative electrode current collector, float life years, and negative electrode corrosion amount (positive electrode / negative electrode material mass ratio = 1.39) Graph showing the relationship between the alloy composition of the negative electrode current collector, the float life years, and the negative electrode corrosion amount (positive electrode / negative electrode electrode material mass ratio = 1.51) The graph which shows the relationship between positive electrode / negative electrode electrode material mass ratio, float lifetime years, and negative electrode corrosion amount The graph which shows the relationship between positive electrode / negative electrode electrode material mass ratio, float lifetime years, and negative electrode corrosion amount

As a result of various studies on the composition of the alloy that improves the corrosion resistance, the present inventor has found that Pb having a Ca content of 0.07% by mass to 0.12% by mass and a Sn content of 0.75% by mass or less with respect to the total mass of the alloy. -Ca-Sn alloy, or Pb-Ca alloy having a Ca content of 0.07 mass% or more and 0.12 mass% or less with respect to the total mass of the alloy forms fine crystal grains and is effective in corrosion resistance. I found out.
Corrosion of a metal having a crystalline structure first occurs along the grain boundaries of the crystal grains. Therefore, in the alloy that forms fine crystal grains, since the depth of intergranular corrosion due to individual crystal grains is small, it is assumed that the corrosion that occurs along the grain boundaries is difficult to proceed. Used for electrical ears.

Here, the current collector of the lead storage battery has a so-called grid (grid) formed by providing bars in a lattice shape or a radial shape, and therefore is generally called a “grid”. The alloy composition of the current collector ear is usually the same as the lattice. However, since the present invention is intended to suppress the corrosion of the ear of the negative electrode current collector, it is important that the ear has the above alloy composition. Of course, the present invention also includes the case where the negative electrode current collector including the ear has the above alloy composition.
In this specification, in accordance with a general name, a negative electrode current collector including an ear may be referred to as a “negative electrode lattice”, and an ear of the negative electrode current collector may be referred to as a “negative electrode ear”.
The alloy composition indicates that the main material is Pb, Ca and Sn, or Pb and Ca (Sn is 0%), and denies the inclusion of other inevitable elements such as Al. Not what you want. The notation “%” in the alloy indicates the ratio to the total mass of the alloy.

By the way, even if it is a lead storage battery which has the negative electrode grid | lattice which consists of the said alloy, in some models used in high temperature environment, the target lifetime years might not be reached.
As a result of investigating the cause, it has been found that the potential is such that corrosion tends to proceed in the vicinity of the welded portion between the negative electrode ear and the strap (hereinafter referred to as “negative electrode strap portion”).

Furthermore, as a result of intensive investigations, a new finding was obtained that the potential of the negative electrode strap portion is affected by the ratio of the mass of the positive electrode material to the mass of the negative electrode material.
In this specification, a material obtained by removing the current collector from the electrode plate and combining a substance (reactive substance) that contributes to the battery reaction and a substance such as an additive or a reinforcing material that does not contribute to the battery reaction is referred to as an electrode material. In this specification, the “electrode material” may be referred to as “active material”, and the “ratio of the mass of the positive electrode material to the mass of the negative electrode material” is hereinafter referred to as “positive electrode / negative electrode material mass ratio”.

FIG. 1 is a graph showing the relationship between potential and corrosion rate.
The relationship between the potential and the corrosion rate was determined by conducting a corrosion test at a constant potential condition of 75 ° C. and 0 to +70 mV (vs Pb / PbSO ₄ ) using the following test cell.
Corrosion rate = (initial thickness−thickness excluding corrosion layer after test) / 2 / test days.
Test Cell Configuration Test Electrode and Counter Electrode: Pure Lead Flat Plate Reference Electrode: Pb / PbSO ₄ Electrode Electrolyte: Specific Gravity 1.28 From FIG. 1, the corrosion rate is in the potential range of +30 to +50 mV (vs Pb / PbSO ₄ ). It is large and it turns out that negative electrode corrosion advances easily.

FIG. 2 is a graph showing the relationship between the positive electrode / negative electrode electrode material mass ratio and the potential of the negative electrode strap portion.
The potential of the negative electrode strap part is a control valve type lead storage battery in which the mass ratio of the positive electrode / negative electrode electrode material is changed to 1.19 to 1.56, 40 ° C. and 2.23 V float charging, and Pb / PbSO ₄ reference Measurements were made with the tip of the pole in contact with the negative strap.
When the mass ratio of the positive electrode / negative electrode material is greater than 1.35 and less than 1.47, the potential of the negative electrode strap portion is a potential of +30 to +50 mV (vs Pb / PbSO ₄ ) where corrosion is likely to proceed. On the other hand, when the mass ratio of the positive electrode / negative electrode electrode material is 1.35 or less, or 1.47 or more, the potential of the negative electrode strap portion is nobler than the potential at which corrosion easily proceeds. Therefore, it is thought that negative electrode corrosion is suppressed.

The action / mechanism that the mass ratio of the positive electrode / negative electrode material affects the potential of the negative electrode strap portion is presumed as follows.
When the mass ratio of the positive electrode / negative electrode material is 1.35 or less, the amount of the positive electrode active material is relatively small, so that the utilization rate of the positive electrode active material is increased, the positive electrode potential becomes noble, and the generation amount of oxygen gas increases. . For this reason, the generated oxygen gas cannot be completely absorbed by the negative electrode plate, and reduction occurs at the negative electrode strap and the ear exposed from the retainer mat. Therefore, the potential of the negative strap part is shifted preciously.
When the mass ratio of the positive electrode / negative electrode material is 1.47 or more, the amount of the negative electrode active material is relatively small, so that the oxygen gas generated at the positive electrode cannot be completely absorbed by the negative electrode plate. Therefore, reduction occurs at the negative electrode strap and the ear exposed from the retainer mat, and the potential of the negative electrode strap portion is shifted preciously.
That is, although the action / mechanism is different between the case where the mass ratio of the positive electrode / negative electrode electrode material is 1.35 or less and the case where it is 1.47 or more, a similar phenomenon occurs in which the potential of the negative electrode strap portion is shifted preciously. Inferred.

If the positive electrode / negative electrode material mass ratio is less than 1.27, the positive electrode active material utilization rate is high, so that the positive electrode deterioration proceeds prior to the negative electrode corrosion, causing a shortened life. Therefore, a positive electrode / negative electrode material mass ratio of 1.27 or more is required.
When the positive electrode / negative electrode material mass ratio is larger than 1.62, there is no particular influence on the life performance. However, in order to ensure energy density, the mass ratio is preferably 1.62 or less, and more preferably 1.56 or less.

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be changed as appropriate according to the common knowledge of those skilled in the art and the disclosure of the prior art.

(Preparation of positive electrode plate)
A positive electrode current collector obtained by casting a positive electrode grid having a thickness of 3.8 mm from a Pb—Ca—Sn alloy containing 0.06% by mass of Ca, 1.5% by mass of Sn, 0.02% by mass of Al, and inevitable impurities. It was. In addition, the alloy composition, dimensions, and design of the positive electrode lattice, and manufacturing methods such as casting, expanding, and punching of a rolled sheet are arbitrary.
Add 99.9% by mass of lead powder by ball mill method and 0.1% by mass of synthetic resin fiber to a positive electrode paste by adding sulfuric acid having a specific gravity of 1.16 at 25 ° C. It dried and produced the positive electrode plate which consists of a positive electrode grid and a positive electrode active material. The paste filling amount was adjusted so that the mass ratio of the positive electrode / negative electrode material after chemical conversion was 1.19 to 1.56. The density and the like of the positive electrode active material are arbitrary.

(Preparation of negative electrode plate)
Thickness 1 made of Pb—Ca—Sn alloy or Pb—Ca alloy containing 0.06 to 0.13% by mass of Ca, Sn 0 to 0.9% by mass, Al 0.02% by mass or less, and inevitable impurities A negative grid of 9 mm was cast, and No. 1 shown in Tables 1 and 2 were cast. It was set as the negative electrode collector used for the battery of 1-90. The dimensions and design of the negative electrode grid are arbitrary.
A lead powder 98.3 wt% of the ball mill method, the synthetic resin fibers 0.1 wt%, carbon black 0.1 wt%, BaSO ₄ 1.4 wt%, and 0.1 wt% lignin, a specific gravity at 25 ° C. 1.14 sulfuric acid was added to form a negative electrode paste, which was filled in the negative electrode lattice, and was aged and dried to prepare a negative electrode plate composed of the negative electrode lattice and the negative electrode active material. The paste filling amount was adjusted so that the mass ratio of the positive electrode / negative electrode material after chemical conversion was 1.19 to 1.56. The density and the like of the negative electrode active material are arbitrary.

(Battery assembly)
Eight positive electrode plates and nine negative electrode plates were laminated through a fine glass mat separator to form an electrode plate group, and the electrode plate was compressed and stored in the battery case until the length of the electrode plate group reached the dimensions in the battery case. . Using pure lead as the additional lead, a positive strap and a negative strap that connect the same polar plates were formed. The strap is not limited to pure lead, and a Pb—Sn alloy can be used.
After adhering the lid to the battery case, sulfuric acid is added as an electrolyte from the liquid injection part of the lid, the battery case is formed, the mass ratio of the positive electrode / negative electrode material is 1.19 to 1.56, and the rated capacity is 200 Ah. A 2V control valve type lead acid battery was assembled.

(Accelerated test)
The following accelerated tests were performed on the produced lead-acid batteries No. 1 to 90.
Test conditions (1) Capacity confirmation test: 25 ° C., 0.2 CA, end voltage 1.75 V / cell (2) Recovery charge: 25 ° C., 2.23 V / cell constant voltage charge (maximum current 0.2 CA), 48 hours (3) Float charge: 50 ° C., 2.23 V / cell × 14 days (4) 5% depth of discharge: 50 ° C., 0.005 CA × 10 hours (5) Float charge: 50 ° C., 2.23 V / cell × The steps (1) to (5) are repeated for 14 days, and the process is terminated when the discharge time is less than 4 hours in the step (1).

(Life judgment)
The two cycles of (1) to (5) were converted to a lifetime of 1 year at 25 ° C., and the float lifetime was determined from the period until the end of the acceleration test. The target float life was 13 years in terms of 25 ° C.

(Anode corrosion amount)
After accelerating the battery, disassemble the battery and take out the negative electrode strap and the cross-section of the welded part of the ear with a metal microscope, check the ear thickness excluding the corroded layer, and calculate the negative electrode corrosion amount using the following formula did.
Negative electrode corrosion amount (%) = (ear initial thickness−ear thickness excluding the corroded layer after the test) / ear initial thickness × 100
Tables 1 and 2 show the results of the life years and the negative electrode corrosion amount.

  No. in Table 1 1-18, no. 19-36, no. The batteries of 37 to 54 use various negative electrode lattice alloys, and have positive / negative electrode material mass ratios of 1.27, 1.39, and 1.51, respectively, and correspond to FIGS. .

  A battery having a positive electrode / negative electrode material mass ratio of 1.39 (No. 19 to 36, FIG. 4) has a large negative electrode ear corrosion amount regardless of the alloy composition of the negative electrode lattice, and the float life is a target value. It is far less than 13 years in terms of ℃.

In a battery (No. 1-18, FIG. 3) having a positive electrode / negative electrode material mass ratio of 1.27, and a battery having a mass ratio of 1.51 (No. 37-54, FIG. 5), the alloy composition of the negative electrode lattice , Batteries in which Ca is 0.06 mass% or 0.13 mass% (No. 1 to 3, No. 16 to 18, No. 37 to 39, No. 52 to 54), and Sn is 0.9 mass % Batteries (No. 7, 11, 15, 43, 47, 51) have a large negative electrode ear corrosion amount and do not achieve the target float life.
On the other hand, the positive electrode / negative electrode electrode material mass ratio is 1.27 and 1.51, and the alloy composition of the negative electrode lattice is Ca: 0.07 to 0.12 mass%, Sn: 0 to 0.75 mass. % (Nos. 4-6, 8-10, 12-14, 40-42, 44-46, 48-50) have a small negative electrode ear corrosion amount and have a life performance exceeding 13 years in terms of 25 ° C. Have.

  Table 2 shows five types of batteries (Nos. 55 to 60, No.) satisfying that the alloy composition of the negative electrode lattice is 0.07 to 0.12% by mass of Ca and 0 to 0.75% by mass of Sn. .61-66, No. 67-72, No. 73-78, and No. 79-84), and the alloy composition of the negative electrode lattice, Ca is 0.06 mass% and Sn is 0.75 mass%. Results (Nos. 4, 22, 40, 6, 24, 42, 9, and 9) in which the positive electrode / negative electrode material mass ratios were varied in the range of 1.19 to 1.56 in the batteries (No. 85 to 90), respectively. 27, 45, 13, 31, 49, 14, 32, 50, 3, 21, 39.), and FIGS. 6 and 7 are graphs of the results.

A battery (No. 85 to 90, FIG. 6) in which Ca is 0.06% by mass and Sn is 0.75% by mass has a large negative electrode ear corrosion amount at any positive electrode / negative electrode material mass ratio. Since the lifetime is short, it can be seen that the alloy composition of the negative electrode lattice is not appropriate.
In the former five types of batteries, when the positive electrode / negative electrode electrode material mass ratio is 1.43 (No. 58, 64, 70, 76, 82), the case of 1.39 (No. 22, 24, 27, 31 and 32), the negative electrode ear corrosion amount is large and the life years are short, so that it is understood that the mass ratio of the positive electrode / negative electrode material is not appropriate.
When the positive electrode / negative electrode electrode material mass ratio is 1.19 (No. 55, 61, 67, 73, 79), the negative electrode ear corrosion amount is small, but the lifetime in terms of 25 ° C. is less than 13 years. Yes. This is because the positive electrode active material utilization rate is high, and the positive electrode deterioration is advanced.
On the other hand, in the former five types of batteries, when the positive electrode / negative electrode electrode material mass ratio is 1.32, 1.35, 1.47 or 1.56 (No. 56, 57, 59, 60, 62) 63, 65, 66, 68, 69, 71, 72, 74, 75, 77, 78, 80, 81, 83, 84) when the positive electrode / negative electrode material mass ratio is 1.27 or 1.51 Similarly to (No. 4, 40, 6, 42, 9, 45, 13, 49, 14, 50), the negative electrode ear corrosion amount is small, and a lifetime of 13 years or more converted to 25 ° C. has been achieved. .

  From the above results, the alloy composition of the negative electrode lattice or the negative electrode ear is Pb—Ca—Sn alloy or Pb—Ca containing 0.07 mass% or more and 0.12 mass% or less of Ca and 0.75 mass% or less of Sn. It is understood that a long-life control valve type lead-acid battery is obtained when the mass ratio of the positive electrode / negative electrode electrode material is 1.27 or more and 1.35 or less, or 1.47 or more.

In addition, the positive electrode / negative electrode electrode material mass ratio can be adjusted by the quantitative ratio of the positive electrode paste filled in the positive electrode lattice and the negative electrode paste filled in the negative electrode lattice as described above.
In order to confirm the mass ratio of the positive electrode / negative electrode material after conversion for a commercially available battery, the battery is disassembled after being charged 100% or more, and the positive electrode plate and the negative electrode plate are taken out. What is necessary is just to measure the mass of electrode material and to calculate mass ratio. Moreover, it is desirable to check with a new battery or a new battery as close as possible.

  According to the present invention, a control valve type lead-acid battery having a long life can be obtained, so that it is useful as a battery for stationary or in-vehicle use.

Claims (2)

  Pb-Ca-Sn based alloy containing Ca 0.07 mass% or more and 0.12 mass% or less, Sn0.75 mass% or less with respect to the total mass of the alloy, or Ca 0.07 mass% with respect to the total mass of the alloy The negative electrode current collector is made of a Pb—Ca alloy containing 0.12% by mass or less and Sn is 0%, and the ratio of the mass of the positive electrode material to the mass of the negative electrode material is 1. It is 27 or more and 1.35 or less, or 1.47 or more and 1.62 or less, The control valve type lead acid battery characterized by the above-mentioned.   Pb-Ca-Sn based alloy containing 0.07 mass% or more and 0.12 mass% or less of Ca, or Sn0.75 mass% or less with respect to the total mass of the alloy, or Ca 0.07 mass% with respect to the total mass of the alloy The negative electrode ear which consists of a Pb-Ca type alloy which contains above 0.12 mass% and Sn is 0% is provided, and the ratio of the mass of positive electrode material to the mass of negative electrode material is 1.27 or more 1. Control valve type lead acid battery characterized by being 1.35 or less, or 1.47 or more and 1.62 or less.