KR20190096320A - Electrode for lead acid battery and lead acid battery system comprising the electrode - Google Patents

Abstract

The present invention relates to a lead acid storage battery system. The present invention relates to a lead acid battery electrode having an enhanced electrode life and performance by forming a porous coating layer on an electrode surface, and a lead acid storage battery system including the same. The lead acid battery electrode comprises: an electrode plate; and a carbon layer containing a water-soluble polymer formed on a surface of the electrode plate.

Description

Electrode for lead acid battery and lead acid based storage system comprising same {Electrode for lead acid battery and lead acid battery system comprising the electrode}

The present invention relates to a lead acid-based storage battery system, and to a lead acid battery electrode including the same and a lead acid battery electrode having improved electrode life and performance by forming a porous coating layer on an electrode surface.

Portable rechargeable energy storage devices, such as rechargeable electrochemical batteries and capacitors, are becoming increasingly essential as power sources in the field of modern transportation and communication means.

Lead-acid batteries have evolved over time as the demand for sources of mobile power has increased. In certain service sectors, flooded lead-acid batteries can be operated in partial state of charge (PSoC), for example approximately 50-80% of charge, which is usually at 100% state of charge. It is different from the normal SLI (startup, ignition and ignition) in operation. For example, a battery of a hybrid electric vehicle (HEV) may operate in a PSoC, eg at approximately 50-80% charge. As a result, the battery may undergo fewer charge / recharge cycles and may not undergo overcharge where dissociation of water generates hydrogen and oxygen and mixes with stratified acid in the cell. have.

The improved lead acid-based battery system is a technology developed to improve the life of existing lead-acid batteries and prevents the growth of local lead sulfate (PbSO ₄ ) crystals and increases PbO due to the increased surface electrical conductivity when a carbon mixture layer is applied to the surface. Helps to recover to ₂ / Pb, improving battery life.

In more detail, in the charging / discharging process, lead crystal (Pb), which is an electrode active material, is changed into lead ions (Pb ²⁺ ). Pb ²⁺ ions form lead sulfate (PbSO ₄ ) crystals during the discharge process. As the lead sulfate crystals grow, the contact area between the electrode surface and the electrolyte decreases and the surface electrical conductivity decreases to form local electron transfer channels. Particularly, lead sulfate crystals are largely formed, and the utilization rate of the electrode active material is decreased, and the life of the battery is drastically reduced because it cannot be returned to PbO ₂ / Pb during the charging process. However, when the carbon mixture layer is applied to the electrode surface, the increased surface electrical conductivity prevents local lead sulfate crystal growth and recovers to PbO ₂ / Pb, thereby improving the life of the battery.

The improved lead-acid-based battery system is intended to improve the life of the electrode by introducing a carbon mixed layer on the electrode surface, but the flow of the electrolyte on the surface of the negative electrode is not smooth because the carbon layer is applied to the negative electrode, resulting in negative electrode surface resistance This raises the problem that the capacity is rather reduced or the life is abruptly reduced.

Accordingly, an object of the present invention is to provide a lead acid battery electrode having a structure capable of solving problems such as an increase in surface resistance due to a lack of electrolyte flow due to a carbon layer coated on a lead acid battery anode.

Another object of the present invention is to provide a lead acid-based storage battery system capable of improving the capacity of the cathode electrode and improving the system life by employing an electrode having a structure in which the electrolyte can contact the electrode smoothly.

The objects of the present invention are not limited to the above-mentioned objects, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object of the present invention, the present invention is an electrode plate coated with a powder; It provides a lead-acid battery electrode comprising a; and a water-soluble polymer containing carbon layer formed on the surface of the electrode plate.

In a preferred embodiment, the water-soluble polymer-containing carbon layer includes a high specific surface area carbon material having a specific surface area of 500 to 3,000 m ² / g, a high conductive carbon material having an electrical conductivity of 20 S / m or more, a water-soluble polymer, and a binder.

In a preferred embodiment, the water-soluble polymer is included 1 to 30 parts by weight per 100 parts by weight of the high specific surface area carbon material, high conductive carbon material and binder.

In a preferred embodiment, the total content of the high specific surface area carbon material is 25 to 80% by weight, the high conductive carbon material is 15 to 70% by weight, and the binder is 1 to 40% by weight.

In a preferred embodiment, the size of the water-soluble polymer is 0.1 μm to 100 μm.

In a preferred embodiment, the water-soluble polymer is selected from the group consisting of poly vinyl alcohol (PVA), poly acrylic acid (PAA), poly vinyl pyrrolidone (PVP) 1 More than

In a preferred embodiment, the binder is at least one selected from the group consisting of polyester, PET, PTFE, PVdF, CMC.

In a preferred embodiment, the water-soluble polymer containing carbon layer is formed to a thickness of 10㎛ to 500㎛, the water-soluble polymer containing carbon layer is dissolved in the water-soluble polymer when the contact with the electrolyte solution to form a plurality of pores.

In addition, the present invention provides a lead acid-based storage battery system comprising any one of the electrodes described above.

In a preferred embodiment, the electrode is a cathode.

First, the lead-acid battery electrode of the present invention forms a plurality of pores in the carbon layer, so that the electrolyte moves more smoothly through the carbon layer, thereby reducing the resistance, thereby improving battery capacity as well as sulfuric acid generated during the charging / discharging process. Lead crystals can grow inside pores without blocking the surface of the electrode, thereby improving electrode life.

In addition, the lead-acid-based storage battery system of the present invention employs an electrode having a structure in which the electrolyte can contact the electrode smoothly, thereby not only improving the capacity of the negative electrode but also improving the system life, thereby implementing a secondary battery having excellent cycle performance. have.

The effects of the present invention are not limited to the above-mentioned effects, and other effects that are not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a graph of a capacity evaluation experiment using the lead-acid battery electrode obtained according to an embodiment of the present invention.
2 is a graph showing the results of life test using the lead-acid battery electrode obtained in accordance with an embodiment of the present invention.

The terms used in the present invention were selected as general terms as widely used as possible, but in some cases, the terms arbitrarily selected by the applicant are included. In this case, the meanings described or used in the detailed description of the present invention are considered, rather than simply the names of the terms. The meaning should be grasped.

Hereinafter, with reference to the accompanying drawings and preferred embodiments will be described in detail the technical configuration of the present invention.

However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The technical feature of the present invention resides in a lead-acid battery electrode having a structure in which a plurality of pores are formed in the carbon layer when the electrolyte layer and the carbon layer are contacted by including a water-soluble polymer in the carbon layer formed on the electrode surface of the lead-acid battery.

That is, when the electrode is assembled by introducing the water-soluble polymer into the carbon layer coated on the surface of the lead electrode support, the water-soluble polymer contained in the carbon layer is dissolved in the electrolyte, and the pores are empty in the space where the water-soluble polymer was present. By the pores, the electrolyte moves more smoothly through the carbon layer and the contact between the electrode and the electrolyte decreases the resistance, thereby improving the battery capacity, and the lead sulfate crystals generated during the charging / discharging process form the electrode surface. This is because it can contribute to the life of the battery by growing inside the pores without blocking.

Accordingly, the present invention provides an electrode support made of lead; And a water-soluble polymer-containing carbon layer formed on the support surface.

The water-soluble polymer-containing carbon layer may include a high specific surface area carbon material, a highly conductive carbon material, a water-soluble polymer, and a binder.

In particular, the water-soluble polymer is to replace the carbon material in a certain amount, it may be included 1 to 30 parts by weight per 100 parts by weight of the high specific surface area carbon material, high conductive carbon material and binder. The weight ratio is determined experimentally, if less than the weight ratio there is a problem that the porosity is formed too small surface resistance is not reduced, if exceeded, the viscosity is too high can be unevenly coated surface when coating the electrode as well as water-soluble There may be a problem of dropping the coating layer containing the polymer.

The total specific surface area carbon material may be 25 to 80 wt%, the high conductive carbon material is 15 to 70 wt%, and the binder may be 1 to 40 wt%. The weight ratio is determined experimentally, if the weight ratio of the binder in the weight ratio is less than the specified weight ratio there is a problem of dropping the active material, if exceeded it may be difficult to permeate the electrolyte solution in the carbon coating layer to increase the interface resistance.

Water-soluble polymers are not limited as long as they are well dissolved in polar solvents such as water and ethanol, but are not limited to polyvinyl alcohol (PVA), poly acrylic acid (PAA), polyvinyl pyrrolidone, PVP) may be one or more selected from the group consisting of. At this time, since the size of the water-soluble polymer determines the size of the pores formed in the carbon layer, it is possible to determine the size of the water-soluble polymer in consideration of the electrical properties such as the fluidity of the electrolyte, in one embodiment the size of the water-soluble polymer is 0.1 μm to 100 μm. If the size of the pores formed in the carbon layer is less than 0.1 μm, there is a problem that the role of electrolyte penetration through the pore formation is difficult, and if it exceeds 100 μm there may be a problem that the surface area of the water-soluble polymer containing coating layer is reduced. In addition, since the water-soluble polymer should be well mixed with the carbon material can be used in a mixed state with the solvent.

The high specific surface area carbon material may be a carbon material having a specific surface area of 500 to 3,000 m ² / g. If the specific surface area of the high specific surface area carbon material is less than 500 m ² / g, the pores are too small to coat the electrode. There is a problem that the electrode performance is poor because it does not penetrate inside, hydrogen generation is promoted due to the excessive specific surface area exceeding 3,000 m ² / g to reduce the electrolyte solution is severe, reducing the life of the electrode. As the high specific surface area carbon material used in the present invention, any known carbon material may be used as long as it is in the above-described specific surface area range, and as an embodiment, it may be any one of activated carbon, carbon black, acetylene black, or a combination thereof. As the high specific surface area carbon material, a powder having a size of 0.1 to 100 μm may be used. When the size of the high specific surface area carbon material is less than 0.1 μm, the stability of the work process is very deteriorated due to scattering of the carbon material, and the electrode layer is exceeded to 100 μm. This is because there is no uniform mixing in constructing the slurry for formation.

The highly conductive carbon material may be a carbon material having an electrical conductivity of 20 S / m or more. If the electrical conductivity of the highly conductive carbon material is less than 20 S / m, the electrical conductivity of the carbon active material decreases, so that the electrical resistance increases when the coating layer is formed. to be. As the highly conductive carbon material used in the present invention, any known carbon material may be used as long as it is in the above-described range of electrical conductivity, and as an embodiment, it may be any one of graphite, graphene, carbon nanotubes, or a combination thereof. . Highly conductive carbon materials may also be used with powders of the same size as the high specific surface area carbon materials.

The binder may be any known polymeric material for the binder, for example, at least one selected from the group consisting of polyester, PET, PTFE, PVdF, CMC. In particular, since the binder must be uniformly mixed with the carbon material, the binder can be used in a mixed state with the solvent.

The water-soluble polymer-containing carbon layer may be formed by preparing a electrode coating slurry including the above-described components by a dip coating method, and the water-soluble polymer contained in the electrode coating slurry is dissolved in the slurry solution in the slurry state. After coating on the electrode is dried on the coating layer of the electrode surface crystallized again. When the electrode manufactured as described above is assembled with the positive electrode to make a unit cell, the electrode contacts the electrolyte, and the water-soluble polymer is dissolved in the electrolyte again, thereby implementing a porous electrode in which pores as large as the crystal size of the aqueous polymer are formed. At this time, the thickness of the water-soluble polymer-containing carbon layer coated on the electrode may be formed from 10㎛ to 500㎛, if the thickness is less than 10㎛ can not expect meaningful performance of the carbon coating, if 500㎛ or more by the carbon layer This is because the electrode surface may be blocked and the electrode performance may be degraded.

In one embodiment, the lead-acid battery electrode of the present invention is manufactured by manufacturing an electrode coating slurry with a water-soluble polymer-containing carbon layer slurry, followed by a dip coating of a lead material electrode support on the electrode coating slurry, followed by a dryer maintained at 25-80 ° C. A water-soluble polymer-containing carbon layer can be prepared by drying at 0.5-10 hours. The electrode coating slurry may be formed of a carbon material (containing carbon in a weight ratio of graphite 1: 1), a binder, and a water-soluble polymer solution. As an embodiment, a 90% by weight carbon material and a 10% by weight binder may be formed. As a solid, a water-soluble polymer-containing carbon layer slurry was prepared such that the total solid concentration was 40% by weight by mixing with a water-soluble polymer solution containing 10% by weight of a water-soluble polymer in distilled water as a solvent.

The lead-acid based storage battery system of the present invention includes the electrode described above. That is, the electrode plate of the above-described structure may be implemented as a secondary battery including at least one of a cathode electrode and a cathode electrode. For example, both the anode and the cathode use the electrode of the present invention, and the separator is disposed between the anode electrode and the cathode electrode. A secondary battery may be realized by a structure impregnated with sulfuric acid.

In particular, the lead-acid based storage battery system of the present invention can implement the above-described electrode as a negative electrode.

Example 1

1. Carbon Material Preparation

Activated carbon was selected as high specific surface area carbon and graphite was selected as high electroconductive carbon, and activated carbon and graphite were ground to prepare a powder having a size of 10-30 μm.

2. Water soluble polymer preparation

PVA was selected as the water-soluble polymer and dissolved in water to prepare a 10 wt% solution.

3. Preparation of slurry for electrode coating

90% by weight of a carbon material (including activated carbon: graphite in a weight ratio of 1: 1) and 10% by weight of CMC as a binder are mixed with a water-soluble polymer solution containing 10% by weight of the distilled water as a solvent as a solid. A slurry for electrode coating was prepared such that the total solid concentration was 40% by weight.

4. Formation of Carbon Layer with Water Soluble Polymer

An electrode having a water-soluble polymer-containing carbon layer having a thickness of 50 μm was prepared through dip coating using an electrode coating slurry on an electrode plate coated with lead.

Example 2

The electrode obtained in Example 1 was used as a cathode electrode, and was fixed to a case using an anode electrode and a separator, and then a unit cell was prepared by impregnating a sulfuric acid solution having a specific gravity of 1.3.

Comparative Example 1

Comparative electrode was prepared in the same manner as in Example 1 except that the water-soluble polymer was not added.

Comparative Example 2

Comparative Example A unit cell was prepared in the same manner as in Example 2 except that the electrode was the cathode electrode.

Experimental Example 1

The capacity of the unit cell and the comparative unit cell obtained in Example 2 and Comparative Example 2 was evaluated as follows and the results are shown in FIG.

The capacity rating is charged until it reaches 2.45V with a current of 0.1C (10-hour rate current), left for 10 minutes for voltage and temperature stabilization, and then discharged with a current of 0.1C until it reaches 1.75V. It was carried out by.

1 shows only the results of the discharge, it can be seen that the capacity of the unit cell including the electrode obtained in the present invention as shown in FIG.

Experimental Example 2

The life of the unit cell and the comparative unit cell obtained in Example 2 and Comparative Example 2 was evaluated as follows and the results are shown in FIG.

For life evaluation, charge each unit cell with a current of 0.1C, and then charge it for 61 seconds at 0.5C (2 hours rate current). The 60 second discharge was repeated at 0.5C. The cycle was terminated when the discharge end voltage reached 1.2V.

As shown in Figure 2 it could be confirmed that the life of the unit cell including the electrode obtained in the present invention is significantly improved.

Although the present invention has been shown and described with reference to the preferred embodiments as described above, it is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

Claims (10)

Electrode plate coated with powder; And
A lead acid battery electrode comprising a; water-soluble polymer-containing carbon layer formed on the surface of the electrode plate.
The method of claim 1,
The water-soluble polymer-containing carbon layer includes a high specific surface area carbon material having a specific surface area of 500 to 3,000 m ² / g, a high conductive carbon material having an electrical conductivity of 20 S / m or more, a water-soluble polymer and a binder. .
The method of claim 2,
The water-soluble polymer is a lead-acid battery electrode, characterized in that it contains 1 to 30 parts by weight per 100 parts by weight of the high specific surface area carbon material, high conductive carbon material and binder.
The method of claim 3, wherein
The sum total content of the high specific surface area carbon material 25 to 80% by weight, the high conductive carbon material 15 to 70% by weight, and the binder is a lead-acid battery multilayer structure electrode, characterized in that 1 to 40% by weight.
The method of claim 1,
The size of the water-soluble polymer is a lead-acid battery electrode, characterized in that 0.1 μm to 100 μm.
The method of claim 5,
The water-soluble polymer is characterized in that at least one selected from the group consisting of poly vinyl alcohol (PVA), poly acrylic acid (PAA), polyvinyl pyrrolidone (PVP) Lead-acid battery electrode.
The method of claim 1,
The binder is a lead-acid battery electrode, characterized in that at least one selected from the group consisting of polyester, PET, PTFE, PVdF, CMC.
The method of claim 1,
The water-soluble polymer containing carbon layer is formed to a thickness of 10 ㎛ to 500 ㎛,
The water-soluble polymer-containing carbon layer is a lead-acid battery electrode, characterized in that the water-soluble polymer is dissolved when a plurality of pores are formed in contact with the electrolyte.
A lead-acid based storage battery system comprising the electrode of any one of claims 1 to 8.
The method of claim 9,
The lead acid-based battery system, characterized in that the electrode is a negative electrode.

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