JP7188398B2 - Valve-regulated lead-acid battery - Google Patents

Description

The technology disclosed in this specification relates to a valve-regulated lead-acid battery.

Valve-regulated lead-acid batteries (sealed lead-acid batteries) are known as one of lead-acid batteries. Valve-regulated lead-acid batteries have a high degree of freedom in installation orientation because they do not contain electrolyte that flows inside. It is used as a power supply for blackout power supplies, communication base stations, motorcycles, and the like (see Patent Document 1, for example).

A valve-regulated lead-acid battery includes a positive plate and a negative plate. The positive plate and the negative plate each have a current collector and an active material supported by the current collector. Further, the valve-regulated lead-acid battery is provided with a separator made of glass fiber and arranged between the positive electrode plate and the negative electrode plate. The separator is impregnated with an electrolytic solution (for example, dilute sulfuric acid). In a valve-regulated lead-acid battery, a positive electrode plate, a negative electrode plate, and a separator are accommodated in a cell chamber while receiving a compressive force in the thickness direction.

JP 2015-69965 A

In a valve-regulated lead-acid battery, the positive electrode plate is accommodated in the cell chamber while receiving a compressive force in the thickness direction. , there is still a risk of falling off of the positive electrode material. Through extensive research, the inventors of the present application have found that when a specific configuration is adopted as the configuration of a valve-regulated lead-acid battery, it is possible to effectively suppress the dropout of the positive electrode material from the current collector. We have newly found that the life characteristics of storage batteries can be dramatically improved.

In the present specification, a technology is provided that effectively suppresses falling off of the positive electrode material from the current collector in the positive electrode plate of the valve regulated lead acid battery, thereby dramatically improving the life characteristics of the valve regulated lead acid battery. disclose.

The valve regulated lead-acid battery disclosed herein comprises a positive plate having a current collector, a positive electrode material supported by the current collector, a negative plate, and a combination of the positive plate and the negative plate. a separator disposed between and made of glass fiber, wherein the compression ratio of the separator is 1.2 or more and 1.8 or less, and the total pore volume per unit mass of the positive electrode material is The positive electrode material contains fibers, and the fibers have an average specific surface area of 0.20 ^{m 2 /} g or more as determined by the BET method using krypton gas as an adsorption gas. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows the external structure of the lead storage battery 100 in this embodiment. 1 is a top view showing the external configuration of a lead-acid battery 100 in this embodiment. FIG. 1 is a top view showing an internal configuration of a lead-acid battery 100 according to this embodiment; FIG. FIG. 3 is an explanatory view showing the YZ cross-sectional configuration of the lead-acid battery 100 at the position IV-IV in FIG. 2; FIG. 3 is an explanatory view showing the YZ cross-sectional configuration of the lead-acid battery 100 at the position of VV in FIG. 2; FIG. 4 is an explanatory view showing the XZ cross-sectional configuration of a portion of the lead-acid battery 100 at the position VI-VI of FIG. 3; FIG. 4 is an explanatory view showing a method of housing the electrode plate group 20 in the cell chamber 16; FIG. 5 is an explanatory diagram showing performance evaluation results; FIG. 5 is an explanatory diagram showing performance evaluation results;

The technology disclosed in this specification can be implemented as the following modes.

(1) The valve regulated lead-acid battery disclosed herein comprises a positive electrode plate having a current collector and a positive electrode material supported by the current collector, a negative electrode plate, the positive electrode plate and the negative electrode. a separator disposed between the plate and made of glass fiber, wherein the compression ratio of the separator is 1.2 or more and 1.8 or less, and the total pores per unit mass of the positive electrode material The volume is 0.150 cm ³ /g or less, the positive electrode material contains fibers, and the average specific surface area of the fibers is 0.20 m ² /g by the BET method using krypton gas as an adsorption gas. That's it. In addition, the positive electrode plate is composed of a current collector and a positive electrode material. That is, the positive electrode material is obtained by removing the current collector from the positive electrode plate, and is generally called an “active material”. The inventors of the present application have conducted intensive studies and found that by adopting the configuration described above, it is possible to effectively suppress the falling off of the positive electrode material from the current collector of the positive electrode plate, thereby prolonging the life of the valve-regulated lead-acid battery. It was newly found that the characteristics can be dramatically improved.

That is, conventionally, no study has been made on the specific surface area of the fibers contained in the positive electrode material. Moreover, even if the specific surface area of the fiber to be contained in the positive electrode material is examined, the adsorption gas used in measuring the specific surface area of the fiber by the BET method is generally nitrogen gas. The inventors of the present application have found that, with regard to various fibers, even if there is no significant difference in the measurement results of the specific surface area of the fibers when nitrogen gas is used as the adsorption gas, krypton gas is used as the adsorption gas to improve the properties of the fibers. By measuring the specific surface area and selectively using fibers having an average specific surface area of 0.20 m ² /g or more, the positive electrode material is effectively prevented from falling off from the current collector of the positive electrode plate. As a result, the inventors have newly found that the life characteristics of a valve-regulated lead-acid battery can be dramatically improved.

However, if the total pore volume per unit mass of the positive electrode material is excessively large, the density of the positive electrode material is excessively low, resulting in a configuration that easily crumbles, so the falling off of the positive electrode material from the current collector cannot be suppressed. may disappear. In addition, if the compression ratio of the separator is too small, the thickness of the separator will decrease as the electrode plates expand and contract due to repeated charging and discharging of the valve-regulated lead-acid battery. The portion that cannot contact with the plate increases, causing a decrease in capacity and a decrease in life characteristics in some cases. In addition, if the compression ratio of the separator is excessively high, the gap inside the separator becomes too small due to excessive pressure applied to the separator, resulting in a state in which the function of the separator to retain the electrolyte is excessively reduced, resulting in a decrease in capacity. life characteristics may be degraded. The inventors of the present application have made intensive studies to determine the compression ratio of the separator to be 1.2 or more and 1.8 or less, and the total pore volume per unit mass of the positive electrode material to be 0.150 cm ³ /g or less. Then, by adopting fibers having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorbing gas as the positive electrode fibers, the positive electrode material is prevented from falling off from the current collector in the positive electrode plate. can be effectively suppressed, and the life characteristics of lead-acid batteries can be dramatically improved.

(2) In the valve-regulated lead-acid battery, the positive electrode material may have a total pore volume of 0.104 cm ³ /g or more per unit mass. It is believed that if the total pore volume per unit mass of the positive electrode material is too small, the reactivity of the positive electrode material will be too low, resulting in poor capacity characteristics of the lead-acid battery. On the other hand, in the present valve-regulated lead-acid battery, the total pore volume per unit mass of the positive electrode material is 0.104 cm ³ /g or more, which is not excessively small. Therefore, according to the present valve-regulated lead-acid battery, it is possible to suppress the deterioration of the reactivity of the positive electrode material, and to dramatically improve the life characteristics of the valve-regulated lead-acid battery while maintaining the capacity characteristics of the valve-regulated lead-acid battery. can be improved.

(3) In the valve-regulated lead-acid battery, the positive electrode material may have a total pore volume of 0.132 cm ³ /g or more per unit mass. According to this valve-regulated lead-acid battery, it is possible to extremely effectively suppress the decrease in reactivity of the positive electrode material. can very effectively improve the capacity characteristics of

(4) In the valve-regulated lead-acid battery, the fibers may be acrylic fibers. According to this valve-regulated lead-acid battery, it is possible to easily obtain fibers having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorption gas.

A. Embodiment:
A-1. Basic configuration:
(Configuration of lead-acid battery 100)
FIG. 1 is a front view showing the appearance configuration of a lead-acid battery 100 according to the present embodiment, FIG. 2 is a top view showing the appearance configuration of the lead-acid battery 100, and FIG. 3 shows the internal configuration of the lead-acid battery 100. 4 is a top view (a view showing a state in which a lid 14, which will be described later, is removed), FIG. 4 is an explanatory view showing the YZ cross-sectional configuration of the lead-acid battery 100 at the position IV-IV in FIG. 2, and FIG. 6 is an explanatory view showing the YZ cross-sectional configuration of the lead-acid battery 100 at the position VV of FIG. 2, and FIG. 6 is an explanatory view showing the XZ cross-sectional configuration of a part of the lead-acid battery 100 at the position VI-VI of FIG. . For convenience of illustration, FIG. 3 shows only a portion (three) of a plurality of electrode plate groups 20 (and straps 52 and 54 connected thereto), which will be described later. In FIG. 5, the illustration of a part of the configuration is omitted so that the configuration of the electrode plate group 20 is shown in an easy-to-understand manner. Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for the sake of convenience, the Z-axis positive direction is referred to as the "upward direction" and the Z-axis negative direction is referred to as the "downward direction." Orientation may be set.

The lead-acid battery 100 of this embodiment is a valve-regulated lead-acid battery (sealed lead-acid battery). Valve-regulated lead-acid batteries have a high degree of freedom in installation orientation because they do not contain electrolyte that flows inside. It is used as a power supply for blackout power supplies, communication base stations, motorcycles, etc. A lead-acid battery 100 includes a housing 10 , a positive terminal member 30 , a negative terminal member 40 , and a plurality of electrode plate groups 20 . Hereinafter, the positive terminal member 30 and the negative terminal member 40 are collectively referred to as "terminal members 30 and 40".

(Configuration of housing 10)
The housing 10 has a battery case 12 and a lid 14 . The container 12 is a substantially rectangular parallelepiped container having an opening on the upper surface, and is made of synthetic resin, for example. The lid 14 is a member arranged to close the opening of the container 12, and is made of synthetic resin, for example. A space hermetically sealed with the outside is formed in the housing 10 by joining the peripheral edge portion of the lower surface of the lid 14 and the peripheral edge portion of the opening of the container 12 by, for example, thermal welding.

A control valve (exhaust valve) 60 is arranged on the lid 14 . The control valve 60 is normally in a closed state, and has a function of opening and releasing the internal pressure when the internal pressure of the lead-acid battery 100 increases.

The space in the housing 10 is divided into a plurality of (six in this embodiment) cell chambers 16 arranged in a predetermined direction (X-axis direction in this embodiment) by a plurality of (five in this embodiment) partition walls 58. partitioned. Hereinafter, the direction in which the plurality of cell chambers 16 are arranged (the X-axis direction) is referred to as the "cell arrangement direction". Each cell chamber 16 in the housing 10 accommodates one electrode plate group 20 . In this embodiment, the space within the housing 10 is partitioned into six cell chambers 16 , so the lead-acid battery 100 includes six electrode plate groups 20 .

(Structure of electrode plate group 20)
As shown in FIGS. 4 to 6, the electrode plate group 20 includes a plurality of positive electrode plates 210, a plurality of negative electrode plates 220, and a separator 230. As shown in FIGS. The plurality of positive plates 210 and the plurality of negative plates 220 are arranged so that the positive plates 210 and the negative plates 220 are alternately arranged. Moreover, the separator 230 is arranged between the positive electrode plate 210 and the negative electrode plate 220 adjacent to each other, and is sandwiched between the positive electrode plate 210 and the negative electrode plate 220 . The electrode plate group 20 may include members other than the positive electrode plate 210, the negative electrode plate 220, and the separator 230 (for example, a nonwoven fabric sheet disposed between the positive electrode plate 210 and the negative electrode plate 220). Hereinafter, the positive electrode plate 210 and the negative electrode plate 220 are also collectively referred to as “electrode plates 210 and 220”.

The cathode plate 210 has a cathode current collector 212 and a cathode active material 216 supported by the cathode current collector 212 . The positive electrode current collector 212 is a conductive member having ribs arranged in a substantially grid-like or mesh-like manner, and is made of lead or a lead alloy, for example. In addition, the positive electrode current collector 212 has a positive electrode tab 214 protruding upward near its upper end. The positive electrode active material 216 contains lead dioxide and positive electrode fibers 217 to be described later. The positive electrode active material 216 may further contain other known additives. The positive electrode plate 210 having such a configuration is obtained by, for example, coating or filling the positive electrode current collector 212 with a positive electrode active material paste containing lead monoxide, water, and dilute sulfuric acid as main components, and drying the positive electrode active material paste. After that, it can be produced by performing a known chemical conversion treatment. The positive electrode active material 216 in this embodiment is obtained by removing the positive electrode current collector 212 from the positive electrode plate 210, and corresponds to the positive electrode material in the claims.

The negative plate 220 has a negative current collector 222 and a negative active material 226 supported by the negative current collector 222 . The negative electrode current collector 222 is a conductive member having ribs arranged in a substantially lattice or mesh pattern, and is made of lead or a lead alloy, for example. In addition, the negative electrode current collector 222 has a negative electrode ear portion 224 protruding upward near its upper end. The negative electrode active material 226 contains lead (spongy lead). The negative electrode active material 226 may further contain other known additives (eg, fiber, carbon, lignin, barium sulfate, etc.). For example, the negative electrode plate 220 having such a configuration is obtained by coating or filling the negative electrode current collector 222 with a negative electrode active material paste containing lead, drying the negative electrode active material paste, and then performing a known chemical conversion treatment. It can be produced by

The separator 230 is a mat-like member made of glass fiber, which is an insulating material, and elastically deformable in the thickness direction. The separator 230 is impregnated with an electrolytic solution (for example, dilute sulfuric acid). Thus, the separator 230 has the function of preventing a short circuit between the bipolar plates 210 and 220 and retaining the electrolyte.

As shown in FIG. 7, the thickness W0 of the electrode plate group 20 when not housed in the cell chamber 16 (hereinafter referred to as "natural state") corresponds to the width of the cell chamber 16 (that is, the width of the adjacent pair of electrodes). is set to a value slightly larger than W1. When manufacturing the lead-acid battery 100, a compression force is applied in the thickness direction to the electrode plate group 20 in the natural state by a pressing device (not shown). As a result, the thickness of the electrode plate group 20 becomes equal to or less than the width W1 of the cell chamber 16 due to the elastic contraction of the separator 230 in the thickness direction. In this state, the electrode plate group 20 is inserted into the cell chamber 16 . When the electrode plate group 20 is accommodated in the cell chamber 16, the electrode plate group 20 receives a compressive force in the thickness direction (the X-axis direction in this embodiment). Therefore, each of the electrode plates 210 and 220 constituting the electrode plate group 20 is in good contact with the separator 230 holding the electrolytic solution.

As shown in FIGS. 3 to 5, the positive tabs 214 of the plurality of positive plates 210 forming the plate group 20 are connected to a positive strap 52 made of lead or a lead alloy, for example. That is, the plurality of positive plates 210 are electrically connected in parallel via the positive strap 52 . Similarly, the negative tabs 224 of the plurality of negative plates 220 forming the plate group 20 are connected to a negative strap 54 made of lead or a lead alloy, for example. That is, the plurality of negative plates 220 are electrically connected in parallel via the negative strap 54 . Hereinafter, the positive strap 52 and the negative strap 54 are collectively referred to as "straps 52, 54".

In the lead-acid battery 100, a negative strap 54 housed in one cell chamber 16 is connected to one side of the one cell chamber 16 (for example, the X-axis positive direction side) is connected to the positive electrode side strap 52 housed in another cell chamber 16 adjacent thereto. In addition, the positive strap 52 housed in the one cell chamber 16 is connected to the other cell chamber 16 adjacent to the other cell chamber 16 on the other side (for example, the X-axis negative direction side) via the connection member 56 . is connected to the negative strap 54 housed in the . That is, the plurality of electrode plate groups 20 included in lead-acid battery 100 are electrically connected in series via straps 52 and 54 and connection member 56 . As shown in FIG. 4, the positive electrode strap 52 housed in the cell chamber 16 positioned at one end (X-axis positive direction side) in the cell arrangement direction is not the connection member 56, but the positive electrode column described later. 34. Further, as shown in FIG. 5, the negative electrode strap 54 housed in the cell chamber 16 located at the end on the other side (X-axis negative direction side) in the cell arrangement direction is not the connection member 56 but the negative electrode column (to be described later). 44.

(Configuration of terminal members 30 and 40)
As shown in FIGS. 1 and 2, the positive terminal member 30 is arranged near one end (X-axis positive direction side) of the housing 10 in the cell arrangement direction, and the negative terminal member 40 is , near the end of the housing 10 on the other side (X-axis negative direction side) in the cell arrangement direction.

As shown in FIG. 4 , the positive electrode side terminal member 30 includes a positive electrode side bushing 32 , a positive electrode column 34 , and a positive electrode side terminal portion 36 . The positive electrode side bushing 32 is a substantially cylindrical conductive member having a vertically penetrating hole, and is made of, for example, a lead alloy. The positive electrode side bushing 32 is embedded in the lid 14 by insert molding. The positive pole 34 is a substantially cylindrical conductive member made of, for example, a lead alloy. The positive electrode column 34 is inserted into a hole of the positive electrode side bushing 32 and joined to the positive electrode side bushing 32 by, for example, welding. The lower end portion of the positive pole 34 protrudes downward from the lower end portion of the positive electrode side bushing 32 and further protrudes downward from the lower surface of the lid 14. ) is connected to a positive strap 52 housed in the cell chamber 16 located at the end of the . The positive terminal portion 36 is, for example, a substantially L-shaped conductive member, and is made of, for example, a lead alloy. The upper end portion of the positive electrode terminal portion 36 protrudes upward from the upper surface of the lid 14 , and the lower end portion of the positive electrode terminal portion 36 is electrically connected to the upper end portion of the positive electrode column 34 . The area around the upper surface of the lid 14 through which the positive terminal portion 36 penetrates is sealed with, for example, a resin member 70 . Note that the positive electrode side terminal portion 36 and the positive electrode column 34 may be an integral member.

As shown in FIG. 5 , the negative terminal member 40 includes a negative bushing 42 , a negative pole 44 , and a negative terminal portion 46 . The negative electrode side bushing 42 is a substantially cylindrical conductive member having a vertically penetrating hole, and is made of, for example, a lead alloy. The negative electrode side bushing 42 is embedded in the lid 14 by insert molding. The negative pole 44 is a substantially cylindrical conductive member made of, for example, a lead alloy. The negative electrode column 44 is inserted into a hole of the negative electrode side bushing 42 and joined to the negative electrode side bushing 42 by, for example, welding. The lower end of the negative electrode column 44 protrudes downward from the lower end of the negative electrode side bushing 42 and further protrudes downward from the lower surface of the lid 14. ) is connected to a negative strap 54 housed in the cell chamber 16 located at the end of the . The negative terminal portion 46 is, for example, a substantially L-shaped conductive member, and is made of, for example, a lead alloy. The upper end portion of the negative electrode terminal portion 46 protrudes upward from the upper surface of the lid 14 , and the lower end portion of the negative electrode terminal portion 46 is electrically connected to the upper end portion of the negative electrode column 44 . A portion of the upper surface of the lid 14 through which the negative terminal portion 46 penetrates is sealed with, for example, a resin member 70 . Note that the negative terminal portion 46 and the negative electrode column 44 may be an integral member.

When the lead-acid battery 100 is discharged, a load (not shown) is connected to the positive terminal portion 36 of the positive terminal member 30 and the negative terminal portion 46 of the negative terminal member 40 , and each electrode plate group 20 is connected to a load (not shown). The power generated by the reaction at positive plate 210 (lead dioxide to lead sulfate) and negative plate 220 (lead (spongy lead) to lead sulfate) is supplied to the load. When charging the lead-acid battery 100, a power source (not shown) is connected to the positive terminal portion 36 of the positive terminal member 30 and the negative terminal portion 46 of the negative terminal member 40, and the power is supplied from the power source. The applied electric power causes a reaction at the positive electrode plate 210 (reaction of lead sulfate to lead dioxide) and a reaction at the negative electrode plate 220 (reaction of lead sulfate to lead (spongy lead)) of each electrode plate group 20, The lead-acid battery 100 is charged.

A-2. Detailed configuration of the lead-acid battery 100:
A-2-1. Detailed configuration of the separator 230:
In the lead-acid battery 100 of the present embodiment, the compression ratio of each separator 230 constituting the electrode plate group 20 accommodated in each cell chamber 16 is 1.2 or more and 1.8 or less. Here, the compression ratio of the separator 230 is the thickness D1 of the separator 230 when the electrode plate group 20 is housed in the cell chamber 16 (hereinafter referred to as the "housed state") as shown in FIGS. to the thickness D0 of the separator 230 when the electrode plate group 20 is not housed in the cell chamber 16 (natural state) (=D0/D1). That is, the compression ratio of the separator 230 is an index value indicating how much the separator 230 in the housed state is elastically contracted from the natural state. In the following description, the condition that the compression ratio of the separator 230 is 1.2 or more and 1.8 or less is referred to as "a specific condition regarding the separator".

Note that the compression ratio of the separator 230 that constitutes the lead-acid battery 100 is specified as follows.
(1) The fully charged lead-acid battery 100 is dismantled according to the Battery Association Standard (SBA), and the electrode plate group 20 is taken out from the cell chamber 16 . When the electrode plate group 20 is taken out from the cell chamber 16, the separator 230 constituting the electrode plate group 20 restores and expands in the thickness direction.
(2) Each electrode plate 210, 220 and each separator 230 constituting the removed electrode plate group 20 are washed with water for 3 hours or more, and then dried.
(3) After drying, the thickness of each positive electrode plate 210 and each negative electrode plate 220 is measured with a vernier caliper. An average value of the measured thicknesses is calculated for each of the plates 210 and 220 . Similarly, after drying, the thickness of each separator 230 (the thickness D0 in the natural state) is measured with a vernier caliper. In addition, since the thickness of the separator 230 is easily changed, the thickness is measured on the basis of 200 N/dm ² . An average value of the measured thicknesses is calculated for each separator 230 .
(4) Measure the width W1 of the cell chamber 16 with a vernier caliper. When the width W1 differs between the upper portion and the lower portion of the cell chamber 16, the average value of the widths W1 of the upper portion and the lower portion is calculated.
(5) Calculate the compression ratio of the separator 230 based on the following formula.
Compression ratio of separator 230 = thickness D0 of separator 230 in natural state/thickness D1 of separator 230 in housed state
Here, the thickness D0 of the separator 230 in the natural state is the measured value in (3) above.
Also, the thickness D1 of the separator 230 in the accommodated state is calculated based on the following formula.
Thickness D1 of separator 230 in accommodated state
=(width W1 of cell chamber 16−(thickness of positive electrode plate 210×number of positive electrode plates 210 constituting electrode plate group 20)−(thickness of negative electrode plate 220×number of negative electrode plates 220 constituting electrode plate group 20) Number of sheets))/(number of positive plates 210 constituting the electrode plate group 20 + number of negative plates 220 constituting the electrode plate group 20 -1)
However, when the electrode plate group 20 includes a member other than the positive electrode plate 210, the negative electrode plate 220, and the separator 230 (for example, a non-woven fabric sheet), the thickness D1 of the separator 230 in the housed state is obtained by the above formula. The value obtained by subtracting the thickness of the other member from the above value.

A-2-2. Detailed configuration of the positive electrode active material 216:
As shown in FIG. 4 , in the lead-acid battery 100 of the present embodiment, the positive electrode active material 216 contains fibers (hereinafter referred to as “positive electrode fibers”) 217 in addition to lead dioxide. In the present embodiment, the average specific surface area of the positive electrode fibers 217 obtained by the BET method using krypton gas as the adsorption gas (hereinafter also simply referred to as “the average specific surface area of the positive electrode fibers 217”) is 0.20 m ² /g or more. is. Since krypton gas has a lower saturated vapor pressure than, for example, nitrogen gas, if krypton gas is used as the adsorption gas for measuring the specific surface area by the BET method, it is possible to accurately measure a relatively low specific surface area. can. For example, if krypton gas is used as the adsorption gas, it is possible to accurately measure the surface area of fine wrinkles on the surface of the positive electrode fiber 217, which is difficult to measure when nitrogen gas is used. Therefore, for various fibers, even if there is no significant difference in the measurement results of the specific surface area of the fiber when nitrogen gas is used as the adsorption gas, when krypton gas is used as the adsorption gas, the specific surface area of the fiber is There may be a significant difference in the measurement results of

The positive electrode fiber 217 is, for example, acrylic fiber, polypropylene fiber, polyester fiber, polyethylene fiber, PET fiber, or rayon fiber. Acrylic fibers are produced by wet spinning, in which a polymer is dissolved in a solvent and fibers are spun in a liquid called a coagulant. At this time, it separates (segregates) into the fiber portion and the solvent portion, and the portion from which the solvent portion has been removed appears as wrinkles. Therefore, in general, many fine wrinkles are formed on the surface of the acrylic fiber. Therefore, the use of acrylic fiber as the positive electrode fiber 217 is preferable because the positive electrode fiber 217 having an average specific surface area within the above-described numerical range by the BET method using krypton gas as an adsorption gas can be easily obtained. . When acrylic fibers are used as the positive electrode fibers 217, the average specific surface area of the positive electrode fibers 217 can be increased up to about 0.40 m ² /g by the BET method using krypton gas as the adsorption gas. .

Further, in the lead-acid battery 100 of the present embodiment, the total pore volume per unit mass of the positive electrode active material 216 is 0.150 cm ³ /g or less. Note that the total pore volume per unit mass of the positive electrode active material 216 is more preferably 0.104 cm ³ /g or more and 0.150 cm ³ /g or less, and more preferably 0.132 cm ³ /g or more and 0.150 cm 3 /g or more. ³ /g or less is more preferable. The total pore volume per unit mass of the positive electrode active material 216 can be adjusted by changing the recipe (mixing ratio of lead powder, water, and dilute sulfuric acid) when manufacturing the positive electrode active material 216 . For example, when the mixture ratio of dilute sulfuric acid and water is increased, the total pore volume per unit mass of the positive electrode active material 216 is increased.

In the following description, the total pore volume per unit mass of the positive electrode active material 216 is 0.150 cm ³ /g or less, the positive electrode active material 216 contains the positive electrode fibers 217, and the krypton gas is adsorbed. The condition that the positive electrode fiber 217 used as the gas by the BET method has an average specific surface area of 0.20 m ² /g or more is referred to as a “specific condition regarding the positive electrode active material”.

The average specific surface area of the positive electrode fiber 217 contained in the positive electrode active material 216 constituting the positive electrode plate 210 of the lead-acid battery 100 by the BET method using krypton gas as an adsorption gas is specified as follows. do.
(1) The lead-acid battery 100 is disassembled, and the positive electrode plate 210 is extracted.
(2) The collected positive electrode plate 210 is washed with water to remove sulfuric acid.
(3) Collecting the positive electrode active material 216 from the positive electrode plate 210 .
(4) The collected positive electrode active material 216 is dissolved in a mixture of nitric acid and hydrogen peroxide.
(5) Filter the solution of (4).
(6) Sample about 0.4 g of sample (fiber) from the residue on the filter paper.
(7) Using a specific surface area measuring device (Tristar II 3020 series manufactured by Shimadzu Corporation), the specific surface area of each fiber is measured by the BET method using krypton gas as an adsorption gas.
(8) Calculate the average value of the specific surface area of each fiber.

Further, the total pore volume per unit mass of the positive electrode active material 216 forming the positive electrode plate 210 of the lead-acid battery 100 is specified as follows.
(1) The lead-acid battery 100 is disassembled, and the positive electrode plate 210 is extracted.
(2) The collected positive electrode plate 210 is washed with water to remove sulfuric acid.
(3) About 1 g of sample (positive electrode active material 216 ) is sampled from the positive electrode plate 210 .
(4) Using a mercury porosimeter (Autopore IV9500 series manufactured by Shimadzu Corporation), the total pore volume of the sampled positive electrode active material 216 is measured by a mercury intrusion method.
(5) Let the average value of the measured values of the total pore volume of each positive electrode active material 216 be the total pore volume per unit mass of the positive electrode active material 216 .

A-3. Performance evaluation:
A plurality of lead-acid battery samples (S1 to S21) were produced, and performance evaluation was performed on the samples. 8 and 9 are explanatory diagrams showing performance evaluation results. Note that the reference sample S5 among the plurality of samples is described in common in FIGS. 8 and 9 (indicated by a thick frame in each figure).

A-3-1. For each sample:
As shown in FIGS. 8 and 9, the samples differ from each other in the compression ratio of the separator, the total pore volume of the positive electrode active material, and the average specific surface area of the positive electrode fiber. More specifically, samples S1 to S13 shown in FIG. 8 all have the same separator compression ratio (1.5), but the total pore volume of the positive electrode active material and the average positive electrode fiber specific surface areas are different from each other. In FIG. 8, the samples S1 to S13 are arranged in ascending order of the total pore volume of the positive electrode active material. They are arranged in ascending order of specific surface area.

Samples S5 and S14 to S21 shown in FIG. 9 all have the same total pore volume of the positive electrode active material (0.104 cm ³ /g), but the compression ratio of the separator and the positive electrode fiber content are the same. are different from each other in average specific surface area. In FIG. 9, the samples S14 to S21 are arranged in ascending order of the compression ratio of the separator, and the samples having the same separator compression ratio are arranged in ascending order of the average specific surface area of the positive electrode fiber. there is

Samples S1 to S3, S6 to S12, and S16 to S19 are specific conditions regarding the separator that the lead-acid battery 100 of the above-described embodiment satisfies (condition that the compression ratio of the separator is 1.2 or more and 1.8 or less). and specific conditions regarding the positive electrode active material (the total pore volume per unit mass of the positive electrode active material is 0.150 cm ³ /g or less, the positive electrode active material contains positive electrode fibers, and krypton gas is condition that the average specific surface area of the positive electrode fiber by the BET method used as the adsorbed gas is 0.20 m ² /g or more).

On the other hand, samples S4, S5, S13 to S15, S20, and S21 do not satisfy one or both of the specific conditions regarding the separator and the specific conditions regarding the positive electrode active material. Specifically, samples S14 and S15 do not satisfy the specific condition regarding the separator because the compression ratio of the separator is relatively small at 1.1. Also, the samples S20 and S21 do not satisfy the specific condition regarding the separator, since the compression ratio of the separator is relatively large at 1.9. In addition, samples S4 and S5 do not satisfy the specific condition regarding the positive electrode active material because the positive electrode fibers have a relatively small average specific surface area of 0.16 m ² /g or 0.18 m ² /g. In addition, the sample S13 does not satisfy the specific condition regarding the positive electrode active material because the total pore volume per unit mass of the positive electrode active material is relatively large, ie, 0.159 cm ³ /g.

In all the samples, acrylic fiber was used as the positive electrode fiber, the average diameter of the acrylic fiber was 16.7 μm, and the aspect ratio of the acrylic fiber (the average length to the average diameter of the fiber ratio) is 30-400. Further, in all the samples, the content ratio of the positive electrode fiber in the positive electrode active material was 0.05% by mass (wt%) to 0.40% by mass. In all samples, the negative electrode active material constituting the negative electrode plate contained PET-based fiber having an average specific surface area of 0.20 m ² /g as determined by the BET method using krypton gas as an adsorption gas. is doing.

The method for producing each sample is as follows.
(1) Preparation of positive electrode plate Raw material lead powder (a mixture of lead oxide containing lead and lead monoxide as main components), water, and dilute sulfuric acid (density: 1.40 g/cm ³ ) A positive electrode active material paste was obtained by mixing with cut synthetic resin fibers (hereinafter referred to as “positive electrode fibers”). It is known that the density of the positive electrode active material can be changed by changing the mixing ratio of dilute sulfuric acid and water. It was realized by changing the compounding ratio of Also, a lead sheet made of a ternary alloy of lead, calcium, and tin (hereinafter referred to as “Pb—Ca—Sn alloy”) was expanded, and then a positive electrode grid (positive electrode current collector) was produced. An unformed positive electrode plate (height: 115 mm, width: 137.5 mm, thickness: 1.5 mm) was obtained by filling the expanded mesh of the positive electrode current collector with the positive electrode active material paste and aging and drying it by a conventional method. got

(2) Preparation of Negative Electrode Plate Raw material lead powder (mixture of lead oxide containing lead and lead monoxide as main components), water, and dilute sulfuric acid (density: 1.40 g/cm ³ ) A negative electrode active material paste was obtained by mixing the cut synthetic resin fibers (hereinafter referred to as “negative electrode fibers”) with a predetermined ratio of negative electrode additives (lignin, carbon, barium sulfate). A lead plate sheet made of a Pb—Ca—Sn alloy was expanded in the same manner as for the positive electrode grid (positive electrode current collector), and then a negative electrode grid (negative electrode current collector) was produced. An unformed negative electrode plate (height: 115 mm, width: 137.5 mm, thickness: 1) was obtained by filling the expanded mesh of the negative electrode current collector with the paste for the negative electrode active material and aging and drying it by a conventional method in the same manner as the positive electrode plate. .3 mm).

(3) Preparation of sample battery Using the positive electrode plate and the negative electrode plate prepared in (1) and (2) above and a mat-like separator made of glass fiber separately prepared, After sandwiching and alternately laminating, a plurality of positive electrode plates and a plurality of negative electrode plates were welded together with lead parts to manufacture an electrode plate group. The above electrode plate group is inserted into a resin (polypropylene) container so that 6 cells are connected in series, and the electrode plate groups (5 locations) are welded between cells, and then a resin (polypropylene) lid is attached. The battery case was joined, and then both terminal portions (positive electrode and negative electrode terminal portions) were welded to produce a sample battery. The compression ratio of the separator was adjusted by adjusting the width of the cell chamber in the container using a spacer. Then, after initial charging by a conventional method, a sample battery having an electrolyte solution density of 1.33 was obtained.

A-3-2. Evaluation items and evaluation methods:
Using each sample of the lead-acid battery, two items of life characteristics and initial capacity characteristics were evaluated.

Evaluation of capacity characteristics was performed as follows. That is, for each sample of the lead-acid battery, the 3-hour rate capacity was measured by the method shown in a) to d) below, and the 3-hour rate capacity of sample S5 was set to 100 (indicated by a thick line in FIGS. 8 and 9). ), and the 3-hour rate capacity in each sample was expressed as a relative value.
a) For the sample, (1) charge for 8 hours with a constant voltage charging method with an upper limit of 14.7 V at a maximum charging current of 0.4 CA, or (2) 5-stage constant current charging method: switching voltage of 14.4 V (Transition to the next charging stage) in the constant current charging method in each of the four stages 0.2 CA → 0.1 CA → 0.05 CA → 0.025 CA plus the fifth stage push-in constant current charging 0.025 CA × 2. The battery is fully charged under the condition of 5 hours (fixed).
b) After charging, leave the sample at 25±2°C, and start the following discharge c) within 5 hours or more and 24 hours or less in a water tank, or 10 hours or more and 24 hours or less in an air tank. do.
c) The sample is discharged at a constant reference current I ₃ (A) until it reaches the final discharge voltage (1.65×the number of cells (V)). Note that the reference current I ₃ (A) is a value obtained by the following formula.
_I3 = C3/ ₃
(However, C3 is the ₃ -hour rate rated capacity (Ah))
d) Measure the discharge duration in c) above to calculate the 3 hour rate capacity.

In addition, evaluation of longevity was performed as follows. That is, each sample of the lead-acid battery was subjected to a life test by the following methods a) to d) to determine the number of lifespans. Assuming that the number of lifetimes in sample S5 is 100 (indicated by a thick line in FIGS. 8 and 9), the number of lifetimes in each sample is expressed as a relative value.
a) Place the sample in an air bath at 25±2° C. for the entire duration of the test.
b) Connect the sample to the life test apparatus, discharge at the reference current I ₃ (A) described above for 2.4 hours, and then charge with the 5-stage constant current charge described above. One cycle of this discharge and charge is defined as one lifetime.
c) Every 50 charge/discharge cycles, the 3-hour rate capacity is calculated by the method described above. However, even when the terminal voltage at the end of discharge in b) above reaches 1.65 V/cell, the 3-hour rate capacity is similarly calculated.
d) If the 3-hour rate capacity calculated in c) above drops to 80% or less of the 3-hour rate rated capacity, the 3-hour rate capacity is calculated again, and the 3-hour rate capacity is less than the 3-hour rate rated capacity. When it is confirmed that the capacity does not exceed 80%, the test is terminated, and the number of lifespans is obtained from a linear relationship between the number of cycles at that point and the capacity. Note that the number of capacity tests in c) above is also added to the number of lifetimes.

A-3-3. Evaluation results:
As shown in FIGS. 8 and 9, the above-described specific conditions for the separator (the condition that the compression ratio of the separator is 1.2 or more and 1.8 or less) and the specific conditions for the positive electrode active material (the unit of the positive electrode active material The total pore volume per mass is 0.150 cm ³ /g or less, the positive electrode active material contains the positive electrode fiber, and the average ratio of the positive electrode fiber by the BET method using krypton gas as the adsorption gas The surface area is 0.20 m ² /g or more), and the samples S1 to S3, S6 to S12, and S16 to S19 all have a result of “113” or more in the evaluation of life characteristics, and the sample Compared to the life characteristic evaluation result of S5, which was "100", the life characteristic was dramatically improved.

On the other hand, in the samples S4 and S5, which do not satisfy the specific conditions regarding the positive electrode active material because the average specific surface area of the positive electrode fiber is less than 0.20 m ² /g, the evaluation of the life characteristics is good at "100" or less. result was not. In samples S4 and S5, since the average specific surface area of the positive electrode fibers is excessively small, the positive electrode fibers do not adhere well to other components in the positive electrode active material, and the binding force of the positive electrode fibers on the positive electrode active material is small. As a result, it is considered that the falling-off of the positive electrode active material from the current collector could not be effectively suppressed, resulting in the deterioration of the life characteristics.

In addition, in the sample S13, which does not satisfy the specific conditions for the positive electrode active material because the total pore volume per unit mass of the positive electrode active material exceeds 0.150 cm ³ /g, the evaluation of the life characteristics is "83", which is not good. No result. Sample S13 has an excessively large total pore volume per unit mass of the positive electrode active material. That is, in sample S13, the density of the positive electrode active material is excessively low, and the structure is likely to collapse. Therefore, in sample ^S13 , lead It is considered that the positive electrode active material collapsed and fell off the current collector as the storage battery was repeatedly charged and discharged, resulting in the deterioration of the life characteristics.

In addition, in the samples S14 and S15, which did not satisfy the specific condition regarding the separator because the compression ratio of the separator was less than 1.2, the evaluation of life characteristics was extremely low, ie, "19" or less. In samples S14 and S15, the compression ratio of the separator is too small. Therefore, in the samples S14 and S15, the thickness of the separator becomes thinner (that is, it does not return to the initial thickness) as the electrode plate expands and contracts due to repeated charging and discharging, and the separator gradually shrinks when the electrode plate shrinks. It is presumed that the portion which could not be contacted with the electrode plate increased and the capacity decreased, resulting in the deterioration of the life characteristics.

In addition, in the samples S20 and S21, which did not satisfy the specific condition regarding the separator because the compression ratio of the separator exceeded 1.8, the life characteristic evaluation was extremely low, ie, "29" or less. In samples S20 and S21, the compression ratio of the separator is too large. Therefore, in samples S20 and S21, the chemical reaction that occurs during charging and discharging and the movement of sulfate ions are blocked. In other words, one of the roles of the separator is to retain sulfuric acid in the interstices of the fibers. becomes. As a result, in the samples S20 and S21, it is considered that the capacity decreased and the life characteristics became low.

In this way, according to this performance evaluation, the lead-acid battery was found to meet the above-described specific conditions regarding the separator (the condition that the compression ratio of the separator is 1.2 or more and 1.8 or less) and the specific conditions regarding the positive electrode active material (positive electrode active material). A positive electrode fiber obtained by the BET method, wherein the total pore volume per unit mass of the substance is 0.150 cm ³ /g or less, the positive electrode active material contains the positive electrode fiber, and krypton gas is used as the adsorption gas. average specific surface area of 0.20 m ² /g or more), the falling off of the positive electrode active material (positive electrode material) from the positive electrode current collector in the positive electrode plate can be effectively suppressed. As a result, it was confirmed that the life characteristics of lead-acid batteries can be dramatically improved.

Although not shown, the acrylic fiber having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorption gas is included only in the negative electrode active material constituting the negative electrode plate. In the sample used as , neither the lifetime characteristics nor the capacity characteristics were good. On the other hand, acrylic fibers having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorbed gas are also used as positive electrode fibers contained in the positive electrode active material constituting the positive electrode plate. In the samples that were also used as negative electrode fibers contained in the negative electrode active material constituting the , the life characteristics and capacity characteristics were equivalent to those of samples S1 to S3, S6 to S12, and S16 to S19. According to these results, by using fibers having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorbing gas, at least as fibers for the positive electrode, the life characteristics of lead-acid batteries are greatly improved. It can be said that it can be improved.

In this performance evaluation, among the samples S1 to S3, S6 to S12, and S16 to S19 that obtained good results, in the samples S6 to S12 and S16 to S19, the total pore volume per unit mass of the positive electrode active material is 0.104 cm ³ /g or more and 0.150 cm ³ /g or less. All of these samples gave a good result of "113" or more in the evaluation of life characteristics, and a good result of "96" or more in the evaluation of capacity characteristics. According to these results, the lead-acid battery satisfies both the above-described specific conditions regarding the separator and the specific conditions regarding the positive electrode active material, and the total pore volume per unit mass of the positive electrode active material is 0.104 cm ³ /g. Above, if it is 0.150 cm ³ /g or less, the total pore volume per unit mass of the positive electrode active material becomes excessively small, so that the reactivity of the positive electrode active material becomes excessively low, and the capacity characteristics deteriorate. It is said that it is possible to suppress the deterioration of the life characteristics due to the excessive decrease in the density of the positive electrode active material due to the excessive increase in the total pore volume per unit mass of the positive electrode active material. I can say Therefore, in the lead-acid battery, both the specific conditions for the separator and the specific conditions for the positive electrode active material are satisfied, and the total pore volume per unit mass of the positive electrode active material is 0.104 cm ³ /g or more and 0.150 cm ³ /g or less is more preferable. Samples S6 to S12 and S16 to S19 had life characteristics equivalent to those of samples S1 to S3, which are advantageous in terms of life characteristics because the total pore volume of the positive electrode active material is relatively small. Although the reason for this is not necessarily clear, by adopting fibers having an average specific surface area of 0.20 m ² /g or more as determined by the BET method using krypton gas as an adsorption gas, samples S6 to S12 and S16 It is a new finding of the present application that even in the numerical range of the total pore volume of the positive electrode active material such as ~S19, it is possible to obtain a lifetime characteristic equal to or greater than that of a configuration with a smaller total pore volume of the positive electrode active material. is.

Among these samples S6 to S12 and S16 to S19, in samples S10 to S12, the total pore volume per unit mass of the positive electrode active material is 0.132 cm ³ /g or more and 0.150 cm ³ /g or less. be. All of these samples gave an even better result of "135" or more in the evaluation of life characteristics, and an extremely good result of "112" or more in the evaluation of capacity characteristics. According to these results, the lead-acid battery satisfies both the specific conditions regarding the separator and the specific conditions regarding the positive electrode active material, and the total pore volume per unit mass of the positive electrode active material is 0.132 cm ³ /g. Above, if it is 0.150 cm ³ /g or less, it is possible to extremely effectively suppress the decrease in reactivity of the positive electrode active material. It can be said that the capacity characteristics of the lead-acid battery can be significantly effectively improved while effectively suppressing dropout. Therefore, in the lead-acid battery, both the specific conditions for the separator and the specific conditions for the positive electrode active material are satisfied, and the total pore volume per unit mass of the positive electrode active material is 0.132 cm ³ /g or more and 0.150 cm ³ /g or less is more preferable.

Acrylic fibers were used as positive electrode fibers in samples S1 to S3, S6 to S12, and S16 to S19, which gave good results in all evaluation items. When acrylic fibers are used as the positive electrode fibers, it is possible to easily obtain fibers having an average specific surface area of 0.20 m ² /g or more by the BET method using krypton gas as an adsorbing gas.

In samples S1 to S3, S6 to S12, and S16 to S19, which obtained good results in all evaluation items, acrylic fibers were used as positive electrode fibers, but other fibers (polypropylene-based fibers) were used as positive electrode fibers. fiber, polyester-based fiber, polyethylene-based fiber, PET-based fiber, rayon-based fiber), if the positive electrode active material including the positive electrode fiber satisfies the above-described specific conditions regarding the positive electrode active material, the positive electrode can be used in the same manner. It is strongly speculated that the dropout of the positive electrode active material (positive electrode material) from the positive electrode current collector in the plate can be effectively suppressed, and the life characteristics of the lead-acid battery can be dramatically improved.

B. Variant:
The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the scope of the invention. For example, the following modifications are possible.

The configuration of the lead-acid battery 100 in the above embodiment is merely an example, and various modifications are possible. For example, in the above embodiment, acrylic fiber, polypropylene fiber, polyester fiber, polyethylene fiber, PET fiber, and rayon fiber are exemplified as the positive electrode fiber 217, but the positive electrode fiber 217 is made of krypton. Other types of fibers may be used as long as the average specific surface area measured by the BET method using a gas as an adsorption gas is 0.20 m ² /g or more.

In addition, in the lead-acid battery 100 of the above embodiment, the negative electrode active material 226 forming the negative electrode plate 220 may satisfy the same specific conditions as the positive electrode active material described above.

Moreover, the manufacturing method of the lead-acid battery 100 in the above-described embodiment is merely an example, and various modifications are possible.

10: Housing 12: Battery case 14: Lid 16: Cell chamber 20: Electrode plate group 30: Positive electrode side terminal member 32: Positive electrode side bushing 34: Positive electrode column 36: Positive electrode side terminal part 40: Negative electrode side terminal member 42: Negative electrode side bushing 44: negative electrode column 46: negative electrode terminal portion 52: positive electrode strap 54: negative electrode strap 56: connection member 58: partition wall 60: control valve 70: resin member 100: lead-acid battery 210: positive electrode plate 212: positive current collector Body 214: Positive electrode ear portion 216: Positive electrode active material 217: Positive electrode fiber 220: Negative electrode plate 222: Negative electrode current collector 224: Negative electrode ear portion 226: Negative electrode active material 230: Separator

Claims (4)

A valve-regulated lead-acid battery,
a positive electrode plate having a current collector and a positive electrode material supported by the current collector;
a negative electrode plate;
a separator disposed between the positive electrode plate and the negative electrode plate and made of glass fiber;
with
The compression ratio of the separator is 1.2 or more and 1.8 or less,
The total pore volume per unit mass of the positive electrode material is 0.150 cm ³ /g or less,
The positive electrode material contains fibers,
The average specific surface area of the fibers measured by the BET method using krypton gas as the adsorbed gas is 0.20 m ² /g or more ,
The valve-regulated lead-acid battery , wherein the content of the fiber in the positive electrode material is 0.05% by mass or more and 0.40% by mass or less . The valve-regulated lead-acid battery according to claim 1,
A valve-regulated lead-acid battery, wherein the positive electrode material has a total pore volume per unit mass of 0.104 cm ³ /g or more. The valve-regulated lead-acid battery according to claim 2,
A valve-regulated lead-acid battery, wherein the positive electrode material has a total pore volume per unit mass of 0.132 cm ³ /g or more. The valve regulated lead-acid battery according to any one of claims 1 to 3,
The valve-regulated lead-acid battery, wherein the fibers are acrylic fibers.

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