KR20210017162A - Manufacturing method of active material for lead acid battery using Multi walled CNT - Google Patents

Abstract

The present invention relates to a method for manufacturing an anode active material for an enhanced flooded battery (EFB) to which a multi-walled CNT is applied and, more particularly, to a method for manufacturing an anode active material for an EFB to which a multi-walled CNT is applied which adds the multi-walled CNT to an expander inputted into an EFB anode at the time of manufacturing the anode active material to increase electrical conductivity, thereby improving durability and performance of the EFB.

Description

Manufacturing method of active material for lead acid battery using Multi-walled CNT {Manufacturing method of active material for lead acid battery using Multi-walled CNT}

The present invention relates to a method of manufacturing a negative electrode active material for EFB using a multi-walled CNT, and more particularly, an enhanced flooded battery (EFB) by adding a multi-walled CNT to an expander that is used when manufacturing a negative active material to an EFB negative electrode to increase electrical conductivity. ). It relates to a method of manufacturing an anode active material for EFB using multi-walled CNT that can improve durability and performance.

Currently, a lead acid battery active material mechanism is adding polyester-based fibers to the active material to secure physical strength and reaction surface area with sulfuric acid.

Typically, polyester-based fibers having a fineness of 0.8 to 5 denier and a length of 1 to 10 mm are added to the lead acid battery active material, and these fibers (fibers) have excellent acid resistance and oxidation resistance.

At this time, the organic synthetic staple fiber added has a generally circular cross-sectional shape, and the length is about 2 to 10 mm.

The components of organic synthetic staple fibers are mainly polypropylene, polyester, and modacrylic, which have excellent acid resistance and oxidation resistance.

In the related art of Korean Patent Registration No. 10-0603908, "electrode plate for storage battery and its manufacturing method", the electrode plate is manufactured by attaching fiber-reinforced paper by applying pressure so that fiber filaments are stuck on the surface of the active material, and filling the active material in the irregularities of the surface. The method is disclosed.

The above-described conventional Korean registered patent relates to "electrode plate for storage battery and its manufacturing method". The electrode plate of the storage battery is coated with an active material having electrochemical activity on a substrate serving as a passage through which electricity flows, and fiber-reinforced paper is applied to the surface of the active material. In the attaching or pressing step, pressure is applied so that the fibrous filaments of the fibrous reinforced paper are stuck to a certain depth, and the active material is filled in the surface irregularities of the fibrous reinforced paper to increase the binding surface area, thereby preventing the active material from being separated from the substrate. In addition, a technology that improves the initial high-rate discharge characteristics of the electrode plate due to the porosity of the fiber-reinforced paper, and also extends the life of the battery by holding and supporting the active material due to the stable support and acid resistance of the fiber-reinforced paper. It is about.

Until now, lead (Pb)-calcium (Ca)-tin (Sn)-based alloys have been used as grid alloys for lead-acid batteries, but this alloy composition alone does not sufficiently cope with the harsh use environment (high temperature and overcharging phenomenon), so the corrosion or corrosion of the grid. It has been pointed out as a problem that the life of the lead acid battery is shortened due to deformation caused by the growth of the battery.

Accordingly, it is required to improve the corrosion resistance and mechanical strength of the grid and to suppress the growth deformation.

Meanwhile, the active material of a conventional lead acid battery is generally based on lead powder and an aqueous sulfuric acid solution, and other additives are mixed according to the characteristics of the positive electrode and the negative electrode, and then mixed to make an active material.

The active material thus made is applied to the substrate, undergoes a aging process and a drying process according to the characteristics of the positive and negative electrodes, and then alternately overlaps the prepared positive and negative plates, and at this time, to prevent an electrical short between the electrode plates. For this purpose, a non-conductive separator is installed, and a positive electrode plate, a negative electrode plate, and a separator are configured to form an electrode plate group.

According to the capacity of the storage battery, several electrode plate groups are connected in series and are accommodated in the roll.

The received electrode plate group undergoes a conversion process, which is supercharged so as to have electrical properties.At this time, lead dioxide (PbO2) is formed in the active material of the positive electrode plate, and due to its characteristics, numerous particles of oxidized lead are combined and the porosity is abundant. The electrolyte is designed to freely diffuse and penetrate the liver.

In addition, the active material of the negative electrode plate is spongy lead (Pb), which is also rich in porosity and reactivity, so that the electrolyte can freely diffuse and penetrate.

The product made in this way can be used in the market.

In addition, in order to facilitate the super charging process and improve the durability of the product, separate aging and drying processes are performed for each polarity.

The aging process of the positive electrode plate is an important process to increase the durability of the product, and lead (Pb), a constituent of the active material, is converted into lead (Pb) as a component of the active material at the hot temperature (about 70 ~ 100℃) and moisture (humidity of 99%) of steam. PbO), but also changes the crystal structure of the active material.

The negative electrode plate can be aged and dried at the same time if left in its natural state without any separate process.

However, if sufficient maturation and drying are not performed, the electrode plate and the electrode plate adhere to each other during the assembly process of forming the electrode plate group, and the durability of the active material decreases due to the presence of moisture, so that the active material embedded between the substrates easily falls even under a small impact.

As the number of times of charge and discharge increases, the active material falls more easily from the substrate by the reaction of lead and sulfuric acid, and the fallen active materials can no longer participate in the reaction. By degrading the performance, the life of the lead acid battery is usually only 1 to 2 years.

Accordingly, there is a demand for a manufacturing process capable of improving the durability and performance of lead storage batteries.

As a conventional technique, the'cathode active material and its manufacturing method and lead acid battery' have disclosed a technique related to an anode active material characterized in that lignin is added to lead powder.

However, it was difficult to expect the above technology to have an effect of improving the life of the active material.

Korean Patent Registration No. 10-0483246

Therefore, the present invention was devised to solve the above conventional problems,

EFB negative electrode active material manufacturing method for EFB using multi-walled CNT that can improve the durability and performance of EFB (Enhanced Flooded Battery) by adding multi-walled CNT to the expander that is used when manufacturing the negative electrode active material. I want to provide.

In order to achieve the problem to be solved by the present invention, a method of manufacturing a negative active material for EFB using a multi-walled CNT according to an embodiment of the present invention,

In the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery),

Multiwalled CNT-added cathode active material mixture manufacturing step (S100) for preparing a negative electrode active material mixture by adding multi-walled CNT to the additive mixture; and

By aging and drying the prepared mixture, a negative electrode plate active material manufacturing step (S200) for preparing an EFB negative electrode plate active material (S200); By including, the problem for improving the durability and performance of the lead storage battery is solved.

Through the method of manufacturing an anode active material for EFB using the multi-walled CNT according to the present invention, the durability and performance of EFB (Enhanced Flooded Battery) are improved by adding multi-walled CNT to the expander that is used when manufacturing the anode active material to the EFB anode to increase electrical conductivity. It provides an effect that can be improved.

1 is a flowchart of a method of manufacturing a negative electrode active material for EFB using multi-walled CNT according to an embodiment of the present invention.
FIG. 2 is an exemplary diagram showing π-bonding of p-orbital present in a multi-walled CNT used in a method of manufacturing a negative electrode active material for EFB to which a multi-walled CNT is applied according to an embodiment of the present invention.
3 is a graph comparing improved products and conventional products manufactured in the method of manufacturing an anode active material for EFB using a multi-walled CNT according to an embodiment of the present invention, and verifying the lifespan in a high-temperature environment according to the American Automobile Engineers Association standard It is a drawing.
4 is a graph comparing an improved product and a conventional product manufactured in the method of manufacturing a negative electrode active material for EFB to which a multi-walled CNT according to an embodiment of the present invention is applied, and is a graph showing a charge importability test.

A method of manufacturing a negative electrode active material for EFB using multi-walled CNT according to an embodiment of the present invention,

In the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery),

Multiwalled CNT-added cathode active material mixture manufacturing step (S100) for preparing a negative electrode active material mixture by adding multi-walled CNT to the additive mixture; and

And a negative electrode plate active material manufacturing step (S200) for preparing an active material for a negative electrode plate of a lead acid battery by aging and drying the prepared mixture.

At this time, the content of the multi-walled CNT in the negative active material mixture,

It is characterized by adding 1wt% of expander containing Carbon, Lignin, BaSO ₄ .

At this time, by the method of manufacturing an anode active material for EFB using the multi-walled CNT,

When the holding capacity of the manufactured EFB is 80Ah ~ 87Ah,

The lifetime is characterized by being able to provide durability improvement within the range of 20% to 25% from 2,304 to 2,400 cycles at 1,920 cycles.

Therefore, by the manufacturing method of the present invention,

It is possible to provide an EFB containing a negative active material for lead-acid batteries using multi-walled CNT.

Hereinafter, it will be described in detail through examples of a method for manufacturing an anode active material for EFB to which a multi-walled CNT is applied according to the present invention.

1 is a flowchart of a method of manufacturing a negative electrode active material for EFB using multi-walled CNT according to an embodiment of the present invention.

As shown in Fig. 1, the method of manufacturing a negative electrode active material for EFB using the multi-walled CNT of the present invention,

In the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery),

Multiwalled CNT-added cathode active material mixture manufacturing step (S100) for preparing a negative electrode active material mixture by adding multi-walled CNT to the additive mixture; and

And a negative electrode plate active material manufacturing step (S200) for preparing an active material for a negative electrode plate of a lead acid battery by aging and drying the prepared mixture.

The present invention is to improve the durability and performance of an EFB (Enhanced Flooded Battery) by increasing the electrical conductivity by adding a multi-walled CNT to an expander that is used when manufacturing an anode active material in an EFB anode.

Conventional lithium ion batteries have used a binder such as PVdF (organic) centered on pre-bonding or CMC (aqueous system) centered on point binding due to high molecular weight in order to increase the bonding force between active materials.

However, manufacturers of lead-acid batteries are currently using polyester-based fiber rather than a powder-type material to increase the bonding strength between active materials.

In the case of polyester-based fiber, it was difficult to expect improved durability and performance because it does not have conductivity.

Therefore, in the present invention, in the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery), multi-walled CNTs are added to the additive mixture to prepare and apply the negative active material mixture, so that the multi-walled CNTs have electrical conductivity. In addition, the overall active material utilization rate was increased and the charging amount compared to the discharge amount was improved.

As a result, it was confirmed through an experiment that the efficiency of the negative electrode active material can be improved and the charging acceptance can be improved.

Specifically, by adding a certain ratio of multi-walled CNTs to an expander containing Carbon, Lignin, BaSO ₄ and additives according to the characteristics of the electrode plate, such as lead powder and sulfuric acid aqueous solution, which are the main components of the conventional active material, Compared to the conventional EFB (=Enhanced Flooded Battery), it was found that it was possible to improve basic performance by more than 5% and improve durability by 25%, and the present invention was completed through confirmation tests.

Next, the manufacturing steps will be described in detail.

The multiwalled CNT-added negative electrode active material mixture manufacturing step (S100) is a process for preparing a negative electrode active material mixture by adding multi-walled CNT to the additive mixture in the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery).

Specifically, the energy emitted in the product is reduced during battery formation and charging and discharging.

This is because the decrease in internal resistance reduces the amount of energy lost during electron transfer.

As shown in FIG. 2, the multi-walled CNT means that a tube-type material connected with a large amount of carbon is made of multiple walls.

Multi-walled CNTs have very high mobility of π-electrons conjugated in π-bonding between carbon p-orbitals, so their electrical conductivity is more than 10,000 times higher than that of all metals.

Since it is about 10 ⁶ times higher than that of Pb, it plays the same role as a jumper circuit for electron transfer even with a small amount.

In addition, compared to multi-walled CNTs, single-walled CNTs have high conductivity and good product quality, but mass production is currently impossible.

Therefore, there is no problem in applying to EFB (=Enhanced Flooded Battery) because the price competitiveness (0.1$/g) of the multi-walled CNT, which can be mass produced at low cost, is high.

Thereafter, the negative electrode plate active material manufacturing step (S200) is a process for preparing an active material for a negative electrode plate of a lead acid battery by aging and drying the prepared mixture.

The negative active material thus made is applied to the substrate, undergoes a aging process and a drying process according to the characteristics of the positive/negative electrode, and then alternately overlaps the prepared positive and negative electrodes, and prevents electrical short between the electrodes. In order to do so, a non-conductive separator is installed, and a positive electrode plate, a negative electrode plate, and a separator are configured to form an electrode plate group.

According to the capacity of the storage battery, several electrode plate groups are connected in series and are accommodated in the roll.

In addition, the content of the multi-walled CNT in the negative active material mixture,

It is characterized by adding 1wt% of expander containing Carbon, Lignin, BaSO ₄ .

In general, short organic synthetic fibers added to the negative active material are added to the active material for the purpose of increasing the mechanical strength of the battery active material.

As for the material, polypropylene, polyester, and modacrylic are used in consideration of acid resistance to an aqueous sulfuric acid solution, which is an electrolyte.

The organic synthetic short fibers used have a circular cross section, which is the specification of conventional synthetic short fibers manufactured by direct spinning, and have a fineness of 2 to 5 denier (diameter is about 12 to 20 micrometers), and the length is 2 to It is 10 millimeters.

The amount added during mixing is 0.1 ~ 0.5 wt%, thereby improving the mechanical strength of the final electrode active material, thereby suppressing the destruction of the active material structure due to contraction and expansion of the active material due to vibration and charge/discharge.

However, since the aforementioned organic synthetic short fibers do not have conductivity, as in the present invention, if multi-walled CNTs are added, they can have electrical conductivity, and increase the total active material utilization rate and increase the amount of charge compared to the amount of discharge. EFB (=Enhanced Flooded Battery) durability improvement and lifespan improvement can be provided.

Therefore, the multi-walled CNT having the above-described characteristics was introduced in the present invention, and by using the multi-walled CNT as an additive to the active material, the effect of maximizing the reaction area of the active material and increasing the electrical conductivity is provided.

As described above, in order to grasp the effect of the present invention, in general, after applying the negative electrode active material, the lead acid battery in which the electrode plate and the strap are combined, and the negative electrode active material containing the multi-walled CNT of the present invention are applied, and then the electrode plate and the strap are applied. Basic performance and lifespan tests for the combined lead acid battery were performed, but a product with a final capacity of 80Ah was produced through subsequent processes such as assembly and chemical conversion, and the lifespan according to SAE J240 standard to verify the lifespan at high temperatures. The test was carried out.

The conventional product to be described later refers to a lead acid battery in which an electrode plate and a strap are combined after applying the active material used in the EFB manufactured by the applicant, and the improved product is the electrode plate and the strip after applying the negative active material to which the multi-walled CNT is added. It refers to the EFB that combines Rob.

As a result of the test, the capacity and lifespan of 87Ah in the holding capacity ended at 2,400 cycles, which was improved by 6% in the holding capacity and 25% in the lifespan compared to the conventional product.

Experimental data on this will be described later.

3 is a graph comparing improved products and conventional products manufactured in the method of manufacturing an anode active material for EFB using a multi-walled CNT according to an embodiment of the present invention, and verifying the lifespan in a high-temperature environment according to the American Automobile Engineers Association standard It is a drawing.

The test standard is a test method for measuring the cycle until the end of its life by repeatedly charging/discharging the EFB at a high temperature (75°C).

(1 cycle: 25A 4 minutes discharge, 14.8V [max 25A] constant voltage 10 minutes charge)

This test is repeated 480 times for one week, and then, after standing for 56 hours, discharged at a high rate of 630A and the voltage at the time point of 30 seconds is measured to determine the state of the EFB.

If the voltage at the time of 30 seconds is more than 7.2V, the battery is judged as intact and the above cycle is repeated. If it is less than 7.2V, the battery is judged as the end of its life and the test is stopped.

<Test Example>

The conventional product to be described later refers to a lead acid battery in which an electrode plate and a strap are combined after applying the active material used in the EFB manufactured by the applicant, and the improved product is the electrode plate and the strip after applying the negative active material to which the multi-walled CNT is added. It refers to the EFB that combines Rob.

division Conventional product Improvement RC 118min 125min CCA 622A 640A C20 82Ah 87Ah Durability (SAE J240) 1,920 Cycle 2,400 Cycle

Table 1 above shows the performance test results of the conventional EFB and the EFB manufactured using the above improved products, showing 1,920 cycles in the case of the conventional product with durability, and 2,400 cycles in the case of the improved product (see Fig. 3).

Therefore, it was confirmed through an experiment that the durability was improved by 25% compared to the conventional conventional product.

1) Reserve Capacity (RC)

Retention capacity RC measures the duration of discharge possible until the discharge end voltage reaches 10.5V with a discharge current of 25A at 25℃ after leaving for 1 hour or more after completion of full charge. For example, this It is a measure of how long the minimum function can be exhibited to operate the load in a stopped state, etc.

As a result of the test, as shown in Table 1, when prepared by applying the negative active material to which the multi-walled CNT according to the present invention is added, the holding capacity (RC) is 126 to 130 minutes, and is precisely 125 minutes, compared to the existing conventional products. In contrast, by showing a 6% performance improvement effect, it was found that the negative active material for lead-acid batteries to which the multi-walled CNT was applied had a positive effect on the holding capacity.

2) Low temperature starting current (CCA: Cold Cranking Ampere)

In general, the rapid discharge characteristics of a storage battery rapidly deteriorate below -10℃. The low-temperature starting current (CCA) is a high-rate discharge test for evaluating the starting ability of a vehicle at low temperatures. Measure the voltage at the time of initial discharge

In this test, the voltage at 30 seconds is required to be more than 7.2V, and the higher it is, the better the performance is evaluated.

In the present invention, the CCA was calculated using a correction formula of (30 second voltage ÷ 6-0.2) × 630.

As a result of the test, as shown in Table 1, the voltage for 30 seconds is 7.15V ~ 7.22V, and the converted CCA is 650A ~ 660A, and it is precisely 640A, showing a 4% performance improvement effect compared to the conventional product It was found that the negative active material for lead-acid batteries to which is applied had a positive effect on the low-temperature starting current.

3) 20 hour rate capacity (AH)

This is to find out the low rate discharge characteristics, by continuously discharging at 3.75A, which is a relatively small current for the EFB capacity, and measuring the discharge capacity (AH) until the voltage reaches 10.5V.

As a result of the test, 85AH ~ 89AH, precisely 87AH, showed a 6% performance improvement effect compared to the existing product, so that the active material for EFB applied with multi-walled CNT had a positive effect on the 20 hour rate capacity (AH). I could see that it was.

4) Life verification test (SAE J240, Cycle)

As a graph (SAE J240) that verifies the lifespan in a 75°C environment according to the standards of the American Association of Automobile Engineers, the test standard measures the cycle until the end of its life by repeating charging/discharging at a high temperature (75°C) of the EFB. It is a test method.

(1 cycle: 25A 4 minutes discharge, 14.8V [max 25A] constant voltage 10 minutes charge)

This test is repeated 480 times for one week, and then, after standing for 56 hours, discharge at a high rate of 630A and measure the voltage at the time point of 30 seconds to determine the state of the battery.

If the voltage at the time of 30 seconds is more than 7.2V, the battery is judged as intact and the above cycle is repeated. If it is less than 7.2V, the battery is judged as the end of life and the test is stopped.

As a result of the test, as shown in FIG. 3, it was found that the EFB active material to which the multi-walled CNT was applied had a positive effect on the increase of the lifespan by showing a 25% improvement in the lifespan compared to the conventional product.

5) Charge acceptance test (CA: Charge Acceptance test)

After discharging a fully charged sample for 2.5 hours at room temperature (25±2℃) with a 5-hour rate current (17.5A based on 70Ah), leave it for 12 hours or more at 0±2℃.

After that, charge it with a constant voltage of 14.4V±0.1V and measure the current for 10 minutes.

As a result of the test, it was found that the current of the improved product increased by 32% in about 10 minutes compared to the conventional product due to high battery conductivity and charging efficiency (see FIG. 4).

division time Conventional product Improvement




Rechargeable income 1 min 27.25 28.17 2 minutes 24.21 26.98 3 minutes 22.14 26.22 4 minutes 21.25 25.52 5 minutes 20.11 24.83 6 minutes 19.35 23.94 7 minutes 18.74 23.46 8 minutes 17.68 22.79 9 minutes 17.04 22.37 10 minutes 16.43 21.78

Through the above-described manufacturing method, multi-walled CNTs are added to the expander that is used when manufacturing the negative electrode active material in the EFB negative electrode to increase the electrical conductivity, thereby providing the effect of improving the durability and performance of the EFB (Enhanced Flooded Battery). do.

Those skilled in the art to which the present invention with the above contents pertains will be able to understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the embodiments described above are exemplified in all respects and should be understood as non-limiting.

S100: Multiwalled CNT additive cathode active material mixture manufacturing step
S200: manufacturing step of active material for negative electrode plate

Claims (4)

In the method of manufacturing an anode active material for EFB applying multi-walled CNT,
In the active material mixing process when manufacturing the negative electrode of EFB (=Enhanced Flooded Battery),
Multiwalled CNT-added cathode active material mixture manufacturing step (S100) for preparing a negative electrode active material mixture by adding multi-walled CNT to the additive mixture; and
A negative electrode active material manufacturing step (S200) for preparing an active material for a negative electrode plate of a lead-acid battery by aging and drying the prepared mixture. A method for preparing a negative electrode active material for EFB using multi-walled CNT, comprising:
The method of claim 1,
The content of the multi-walled CNT in the negative active material mixture,
A method of manufacturing an anode active material for EFB using multi-walled CNT, characterized in that 1 wt% of an expander containing Carbon, Lignin, and BaSO ₄ is added.
The method of claim 1,
By the method of manufacturing an anode active material for EFB using the multi-walled CNT,
When the holding capacity of the manufactured EFB is 80Ah ~ 87Ah,
A method for manufacturing an anode active material for EFB using multi-walled CNT, characterized in that it can provide durability improvement within the range of 20% to 25% from 1,920 cycles to 2,304 to 2,400 cycles.
By the manufacturing method of claim 1,
EFB containing negative active material for lead acid battery applied with multi-walled CNT.

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