KR20160017243A - MANUFACTURE METHOD OF POCKET TYPE Ni-Zn BATTERY - Google Patents

Abstract

Provided in the present invention is a manufacturing method of a nickel-zinc pocket-type battery, capable of preventing the separation of a negative electrode active material from the inside of a strip, and extending the lifespan by coating a separation membrane of a negative electrode and a positive electrode with a polymer solution and preventing the leakage of active material powder. The method comprises the steps of: (a) manufacturing two sheets of surface-perforated Ni strip as a pocket shape formed with an insertion hole; (b) evenly charging the active material to the inside of the insertion hole; (c) contacting two sheets of metal plate to a capsulated negative electrode or positive electrode active material by applying external force to the metal plate; (d) manufacturing one electrode plate by inserting the needed amount of the strip in between a rug and a side bead, and coupling the same; (e) group-assembling the completed electrode plate, and connecting a pole rod to an external terminal; and (f) filling the group-assembled electrode plate with an electrolyte inside a case.

Description

TECHNICAL FIELD [0001] The present invention relates to a nickel-zinc pocket-type battery,

The present invention relates to a negative electrode active material for use in a nickel-zinc pocket-type battery, in which the negative active material is not easily detached from the inside of the strip, and a polymer solution is coated on the separator between the negative electrode and the positive electrode to prevent leakage of the active material powder, And a method of manufacturing a nickel-zinc pocket-type battery.

Industrial batteries are generally used for emergency power sources. The voltage of the power supplied to the factory is usually 220V, and the industrial battery is a set of unit cells and operates in parallel with the uninterruptible power supply (UPS) by designing the voltage of 220V and the required current as the capacity of the battery (Ah). If the industrial power supply is suddenly short-circuited under the designed emergency power supply, the industrial battery will be supplied with emergency power.

Lead-acid batteries, nickel-cadmium (Ni-Cd), and nickel metal hydride (Ni-MH) batteries are examples of industrial batteries. The lead battery uses a nominal voltage of 2V and 110 cells at 220V of the industrial voltage. The Ni-Cd and Ni-MH cells have a nominal voltage of 1.2V, and 184 cells are used for 220V voltage supply. In order to overcome the harmful effects of lead and cadmium batteries, it is urgent to complement the nominal voltage among the nickel-based batteries and to develop batteries with low-cost active materials.

Pocket-type electrode plates are technologies applied to nickel-based large-capacity batteries such as Ni-Fe, Ni-Cd and Ni-MH. For battery output of low rate, medium rate and high rate, steel strips of each rate are perforated to nickel plating, the upper and lower steel strips are filled with active material, and the ribbons are assembled according to the electrode plate capacity . This not only serves to support the active material, but also serves as a current collector for the electrode. At the same time, side reactions of the electrolyte and the electrode plate are prevented, and the alkali resistance property of the electrode plate is increased in the electrolytic solution of the strong alkaline component, thereby ensuring durability and performance reliability. By containing a large amount of electrolytic solution, it is possible to uniformly charge and float the battery without additional control device even if a small overcharge is allowed by controlling the inter-cell voltage and charge amount evenly during charging. The electrolyte consumed by the small amount of gas generated at this time is continuously replenished from the outside. The electrode active material is surrounded by the current collector of the outer periphery, so that the large current stability is excellent compared with other types of cells.

In the case of Ni-Zn pocket-type batteries, J. Drumm developed a large-capacity battery for 440V / 600Ah in 1931 and used it until 1949. However, with the advent of engines using fossil fuels, have. Despite this background, it is necessary to review the nickel-zinc pocket-type battery because the closed capacity and MF capacity of the battery are limited.

      The most problematic of the nickel-zinc battery is that the zinc or zinc oxide used as the anode active material is dissolved in the alkaline electrolyte and thus the dendrite is formed on the surface of the negative electrode plate. In particular, in the case of a pocket type battery, since the electrode plate is a flooded type in which the electrolyte is completely immersed in the electrolyte, the amount of the negative electrode active material dissolved in the electrolyte increases. This property causes the deterioration of the conductivity of the negative electrode active material in the negative electrode plate and the decrease in the capacity due to the insufficient reaction with the positive electrode active material. In addition, the active material may accumulate on the surface of the negative electrode plate to cause dendrite.

     Pocket-type batteries have a very rough surface because they use a current collector as a strip that generates a micro-hole that serves to impregnate the electrolyte into the active material. Since the electrode active material is wrapped in the strip serving as the current collecting body, the current collector is in direct contact with the electrolyte, so that the filling material of zinc and zinc oxide dissolved in the electrolyte is likely to be deposited on the surface of the current collector. Since the precipitated dendrite causes an internal short circuit, solving this problem is an important issue in battery development.

Disclosure of the Invention The present invention has been made to solve the above two problems, and an object of the present invention is to modify an anode active material used in a nickel-zinc pocket-type battery to form an optimal granule so that the anode active material does not easily separate from the inside of the strip. And a method of manufacturing a nickel-zinc pocket-type battery.

Another object of the present invention is to provide a method of manufacturing a nickel-zinc pocket-type battery in which a polymer solution is coated on a separator between a cathode and an anode to prevent leakage of the active material powder and prolong life.

Another problem to be solved by the present invention is to reduce the solubility of the negative electrode by using EG-EKNL (ZnO saturation, KOH: NaOH: LiOH = 3: 2: 1) as an electrolyte filled in the case to form a nickel- And a method for manufacturing the same.

The method of manufacturing a pocket type nickel-zinc battery according to the present invention comprises the steps of: (a) fabricating two Ni strips whose surfaces are perforated in a U-shaped concavo-convex shape, (b) uniformly filling the prepared active material into the interior of the insertion hole; (c) applying an external force to the metal plate to bring the two metal plates into contact with the encapsulated negative electrode or the positive electrode active material; (d) inserting the strip by a required amount between a lug protruding through the through hole and the side bead, and bonding the strip with a press press or the like to manufacture one plate; And (e) laminating the completed electrode plate alternately with a cathode, a separator, and an anode according to a battery capacity, assembling the assembly into a plate assembly, and connecting the polarizer terminal to an external terminal post; (f) filling the assembled electrode plate with electrolytic solution inside the case,

The anode active material is a mixture of Ni (OH) ₂ , CoO and Carbon, or ZnO, AB, Ca (OH) ₂ , Bi ₂ O ₃ , and Acrylic Binder. , AB, Acrylic, Ca (OH) ₂ , Bi ₂ O ₃ , PTFE, Binder b, Binder c, and CMC.

Based Preferably, the total weight of the positive electrode active material for a Ni (OH) ₂ 85% by weight, CoO 7% by weight, Carbon 8% by weight is used, or ZnO 89.0% by weight, AB 2.0% by weight, Ca (OH) ₂ 4.0 By weight, Bi ₂ O ₃ 3.0% by weight, Acrylic Binder 2.0% by weight,

Negative electrode active material for 84 to 90% by weight, based on the total weight of ZnO (S), AB 1.5 ~ 2 weight%, Acrylic 0 ~ 3% by _{weight, Ca (OH) 2 2 ~} 3% by weight, Bi ₂ O ₃ 3.5 ~ 4 to 4 wt%, PTFE 0 to 0.6 wt%, Binder b 0 to 2 wt%, Binder c 0 to 0.4 wt%, and CMC 0 to 1 wt% are used.

Preferably, the surface of the cathode and the anode or the separation membrane is coated with a solution of a polyacrylic acid partial potassium salt (PAAK) polymer.

Preferably, the electrolytic solution is EG-EKNL (KOH: NaOH: LiOH = 3: 2: 1) saturated with ZnO.

1 is a graph showing charge / discharge behaviors of 100Ah test cells of four types of Ni-Zn pocket type according to the present invention.
FIG. 2 is a graph showing the cycle characteristics according to an electrolyte solution of a cell manufactured using the active material of composition (A) in FIG.
3 is a cycle graph showing the behavior of a Ni-Zn pocket-type 300 Ah battery according to the present invention.
4 is a charge / discharge graph of a Ni-Zn pocket-type 300 Ah battery according to the present invention.

Hereinafter, a nickel-zinc pocket-type battery according to the present invention will be described in detail with reference to the accompanying drawings.

The nickel-zinc pocket-type battery is manufactured by (a) two Ni strips (T = 0.1 mm, W = 16, 23, 25 mm) having a perforated surface, Fabricating in the form of a pocket; (b) uniformly filling the prepared active material into the interior of the insertion hole; (c) applying an external force to the metal plate to bring the two metal plates into contact with the encapsulated negative electrode or the positive electrode active material; (d) inserting the strip by a required amount between a lug protruding through the through hole and the side bead, and bonding the strip with a press press or the like to manufacture one plate; And (e) The completed electrode plates are alternately stacked one by one with a cathode, a separator and an anode in accordance with the battery capacity, assembled into a plate assembly, and a polar terminal is connected to an external terminal step; (f) The assembled electrode plate is made of pocket-type nickel-zinc battery by filling electrolyte inside the case. This nickel-zinc pocket-type battery is described in detail in Registration No. 10-0878343, which was filed by the inventor of the present invention, and thus a detailed description thereof will be omitted.

The present invention also provides a positive electrode active material for a nickel-zinc pocket-type battery, comprising Ni (OH) ₂ , CoO and Carbon, or a mixture of ZnO, AB, Ca (OH) ₂ , Bi ₂ O ₃ , And it is preferably made of particles of about 500 to 700 mu m. At this time, based on the total weight of Ni (OH) ₂ 85% by weight, CoO 7%, Carbon 8% by weight is used, or ZnO 89.0% by weight, AB 2.0% by weight, Ca (OH) ₂ 4.0% by weight, Bi ₂ 3.0 wt% of O ₃ , and 2.0 wt% of Acrylic Binder are preferably used. Such granulated anode active material is not separated between the perforated Ni strips so that the amount of loss is small, and workability is excellent, so that it is easy to manufacture an electrode plate and a certain amount is injected into the Ni strip, thereby reducing the deviation of the electrode plate.

The anode active material is prepared by mixing ZnO (S), AB, Acrylic, Ca (OH) ₂ , Bi ₂ O ₃ , PTFE, Binder b, Binder c, CMC and the like. Based on the total weight, 84 to 90 wt% of ZnO (S), 1.5 to 2 wt% of AB, 0 to 3 wt% of Acrylic, 2 to 3 wt% of Ca (OH) ₂ , 3.5 to 4 wt% of Bi ₂ O ₃ 0 to 0.6% by weight of PTFE, 0 to 2% by weight of Binder b, 0 to 0.4% by weight of Binder c and 0 to 1% by weight of CMC are preferably used. Such an anode active material may be formed into particles larger than the pore size of the surface of the Ni strip, or may be formed into a predetermined size by drying at a high temperature after the slurry is prepared, or may be manufactured into a square chip having a predetermined size. Particularly, desirable.

In the meantime, the surface of the anode plate and the cathode plate or the separation membrane is coated with a solution of a polyacrylic acid partial potassium salt (PAAK) polymer. As a measure to prevent leakage of the active material powder by the coating of the polymer solution, binding of the active material is less required.

Further, in the present invention, it is preferable to use EG-EKNL (ZnO saturation, KOH: NaOH: LiOH = 3: 2: 1) having a specific gravity of 1.226 as an electrolyte to be filled in the case. With such ZnO, EG-EKNL can decrease the solubility of the cathode due to ZnO saturated in the electrolyte, thereby increasing the efficiency and lifetime of the battery.

Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these examples.

≪ Example 1 > Production of 100 Ah plate and battery

First, a negative electrode active material to be produced on the electrode was prepared in accordance with the compositional table of Table 1, dried in an oven at 90 ° C for 24 hours, finely molded with particles of a predetermined size, and finally classified into 500 μm mesh .

Composition Ni (OH) ₂ CoO Carbon Composition ratio (wt%) 85 7 8

The cathode active material was slurried according to the compositional table of Table 2, and then granulated to about 500 to 700 μm.

Composition ZnO (S) AB Acrylic Ca (OH) ₂ Bi ₂ O ₃ PTFE Binder b Binder c CMC Composition ratio (A) 89.0 2.0 3.0 2.25 3.75 0 0 0 0 Composition ratio (B) 85.56 1.94 3.0 2.13 3.49 0.58 1.94 0.39 0.97 Basic composition ratio wt% 88.2 2.0 0 2.2 3.6 0.6 2.0 0.4 1.0

- Composition (A) Drying: 3% acrylic binder instead of conventional binder

- Composition (B) Wetting: Use both conventional binder and 3% acrylic binder

On the other hand, the electrode plate was prepared by forming a quadrangular pellet by inserting the classified anode active material into a mold having a size of 0.8 cm to 5 cm and inserting it into a strip having a width of 16 mm. These bonds were made into a mat having a size of 14 cm * 21 cm according to the electrode manufacturing process. At this time, the capacity per one anode was set to 15 Ah, and the capacity ratio between the cathode and the anode was set to 3: 1.

The fabricated positive and negative electrodes were alternately laminated with 11 and 12 sheets, respectively, to form a group of electrode plates having a discharge capacity of 100 Ah, which were then compressed and fixed using a banding machine. For the anode, two 90 μm nonwoven fabrics of NKK were used as the anode separator, and a cathode was used as the cathode separator. Microporous polyolefin 3407 and CELGARD polyolefin 3407 were used as cathode separator. Finally, a pocket-type nickel-zinc battery was assembled and filled with electrolyte EG-EKNL (ZnO saturation, KOH: NaOH: LiOH = 3: 2: 1) having a specific gravity of 1.226 to the height between the upper part of the electrode plate and the external connection terminal, After a stabilization time of 6 hours or more, charge and discharge tests were carried out. A total of four test cells were fabricated, and the characteristics of each test cell in terms of manufacturing characteristics and charge / discharge conditions are shown in Table 3.

Cell No. anode
(No.) cathode
(No.) Anode: cathode
Capacity ratio Purpose of experiment
(Anode active material change test) Charge / discharge condition Electrolyte cell 1 10 12 1: 3.44 Pocket type battery TEST, 100Ah class, gun mixture 0.2C-0.1C, 80% / 0.3C EG-EKNL cell 2 10 12 1: 3.44 Pocket type battery TEST, 100Ah class, gun mixture 0.2C-0.1C, 80% / 0.3C EG-EKNL cell 3 10 12 1: 3.51 Pocket type battery TEST, 100Ah class, wet mixing 0.2C-0.1C, 80% / 0.3C EG-EKNL cell 4 10 12 1: 4.10 Pocket type battery TEST, 100Ah class, reference powder 0.2C-0.1C, 80% / 0.3C EG-EKNL

<Test Results>

The charging / discharging conditions of the 100Ah class test cell are shown in Table 4.

Charge Discharge Formation 3 step 0.1 C
1.2 V cut-off Chg./Dischg. 0.2 C 2.4 h 0.3 C 0.1 C 3.2 h

The battery is subjected to a formation / activation process prior to full-scale testing of charging / discharging of the battery. The process proceeded to 3 steps and was charged to 91% over 11 hours in the order of 0.15C-0.05C-0.03C, discharged at 0.1C, and cut off at 1.2V at the termination voltage. This process was repeated twice, and charge / discharge experiments were performed. The charge was maintained at 0.2 C for 2.4 hours and 0.1 C for 3.2 hours to charge up to 80% of the capacity and discharged at 0.3 C to cut off at 1.2 V. [

Fig. 1 shows charge / discharge behavior of four 100Ah class test cells. As shown in Fig. 1, the cells 1 and 2 were made of the composition (A), the cell 3 was the composition (B), and the cell 4 was made of the negative electrode active material of the basic composition. Cells 1 and 2, fabricated by dry mixing of active materials, are composed of an active material with only an acrylic binder and have almost the same cell behavior. This means that there is little variation in electrode manufacturing process.

On the other hand, the cell 4 of the composition using the basic binder after removing the acrylic binder shows the best capacity up to 110 cycles, but thereafter, it rapidly drops. It is interpreted that the binder capacity of about 3% initially exhibits excellent characteristics due to a small internal resistance, and the capacity is rapidly lowered due to the weakening of the binder. Cell 3, in which the binder was added in excess of about 6%, showed a low capacity as a whole due to its high internal resistance, but has a relatively longer life than Cell 4.

In addition, it is considered that the Acrylic binder plays an important role in the battery performance, especially in the change of the cathode composition, especially the performance of the battery according to the change of the binder. If the amount of the binder added is large as a whole, the capacity of the battery is reduced, while if it is less, the life is shortened. As a result, it is possible to optimize battery life and capacity by adjusting the amount of acrylic binder rather than other binders.

Another factor that has a decisive influence on the performance of the battery is the electrolyte. The electrolyte is a path through which ions move when the anode and the anode active material react. The efficiency and lifetime characteristics of the battery can be optimized by adjusting the ionic conductivity according to the composition and specific gravity of the electrolyte. Generally, the higher the specific gravity of the electrolyte, the higher the ionic conductivity. When the specific gravity is higher than the specific gravity, the ionic conductivity is lowered by acting as a resistance.

Electrolyte of low specific gravity is mainly used for the dissolution phenomenon of the zinc anode filling material, which is a main problem of the nickel-zinc secondary battery, in the electrolyte solution. However, in order to improve the ionic conductivity, it is necessary to modify the electrolyte, such as the addition of buffer and the use of a zinc saturated electrolyte, in order to minimize the dissolution of the electrode active material while increasing the specific gravity.

FIG. 2 is a graph showing the cycle characteristics according to an electrolyte solution of a cell manufactured using the active material of the composition (A). FIG. Test cell 1 and cell 2 were made by dry mixing with the same composition of active material, but differ only in the electrolytic solution. EG-EKNLZ was prepared by saturating ZnO with the same concentration of a three-component electrolytic solution (EG-EKNL). The former was applied to cell 1 and the latter was applied to cell 2.

As a result of observing the behavior of the battery, the electrolyte solution saturated with ZnO showed excellent capacity and life characteristics. This is because the solubility of the negative electrode was reduced due to the ZnO saturated in the electrolyte solution, and the dissolution of the negative electrode was a decisive factor in the efficiency and life span of the battery.

&Lt; Example 2 > Preparation and test of 300 Ah class batteries

The 300 Ah class battery was manufactured by connecting the above-described 100 Ah batteries in parallel. It is actually difficult to connect dozens of plates to one pole, and there are more disadvantages than the advantages of heat generation. Therefore, the fabrication of the test cell is almost the same as the fabrication of the 100 Ah cell described above, but the largest difference is that the cell connection terminal and the cell case are enlarged.

The composition of the electrode is the same as that of the battery of 100 Ah in the case of the anode. As shown in Table 5, the composition of the negative electrode was a composition using only Acrylic Binder as the binder. Use of an excessive binder may increase the internal resistance of the battery. On the other hand, 5% of a polymer solution of PAAC (Polyacrylic Acid Partial Potassium Salt) was coated on the separator between the cathode and the anode. This is an additional measure to prevent leakage of active material powder from the electrode plate. The test cell was fabricated by applying PAAK to the anode and anode separator.

ZnO AB Ca (OH) ₂ Bi ₂ O ₃ Acrylic Binder Furtherance(%) 89.0 2.0 4.0 3.0 2.0

The battery was composed of 34 positive electrodes and 32 negative electrodes, and the electrolyte was filled with a specific gravity of 1.31 EG-EP # 7 (KOH: NaOH = 3.86: 1) and then aged at room temperature for 24 hours . EG-EP # 12 (specific gravity 1.31) was used as a replenisher.

<Test Results>

As shown in Table 6, in the charge / discharge test of the 300 Ah battery, the above-described formation / activation of the battery was performed. This process proceeded to 3 steps and was charged to 91% over 11 hours in the order of 0.15C-0.05C-0.03C, discharged at 0.1C, and cut off at 1.2V. This procedure was repeated two times and then charged / discharged. In the case of charging, the battery was charged up to 80% of the capacity while maintaining 0.2C for 2.4 hours and 0.1C for 3.2 hours until 22 cycles. The discharge was cut off at 1.2V at 0.3C.

Charge Discharge Formation 3 step 0.1 C 1.2 V cut-off Chg./Dischg.(3-22cycle) 0.2C? 0.1C 0.3 C Chg./Dischg.(23cycle~) 0.2C

3 is a cycle graph showing the behavior of Ni-Zn pocket-type 300 Ah class batteries. In the graph, red indicates charge and blue indicates discharge. 3 (a) is a cell 1, and FIG. 3 (b) is a PAAK coating (cell 2) between cathode separators.

As shown in FIG. 3, the charging process is performed in a stepwise manner. In the initial 2 cycle formation process, the charging time is more than 400 Ah, which is much more than the design capacity of the battery. 3-step method.

Test results show that Cells 1 and 2 coated with a gel electrolyte between the anode and cathode separator have improved behavior compared to the above-described battery test of 100 Ah. In particular, it is more effective to coat the anode separator than the anode separator. In the case of cell 2 coated on the cathode separator, it exceeds 350 cycles (350 cycles from @ 80% DOD condition to 75% initial capacity retention). This is comparable to conventional paste-type batteries and shows performance applicable to industrial batteries at 300Ah.

4 is a charge / discharge graph of a Ni-Zn pocket-type 300 Ah class battery. As shown in FIG. 4, in the charging curve, a drop of the voltage at about 230 Ah in a 10 cycle (red) curve is a phenomenon in which the charging current is lowered at 0.2 C charging and 0.1 C charging. Thereafter, the charge current is kept at 0.2C at over 50 cycles, and there is no voltage drop phenomenon. Overall, these charging conditions show conditions that do not cause overcharging or other battery run-down. On the other hand, the capacity curve of the discharge curve suddenly decreases from 250Ah to 300 cycles.

As can be seen from the above, it can be confirmed that the nickel-zinc pocket-type battery according to the present invention plays a very important role in the binder and electrolyte used for the active material in improving the performance of the battery. Acrylic binders were more effective in binder and electrolyte solution was effective in extending the life of saturated solution of ZnO. If the amount of the binder is large, the influence of the internal resistance of the battery becomes large, and the saturated electrolyte is interpreted to suppress the dissolution of zinc.

In addition, in the test of the 300 Ah battery cell, the battery in which the PAAK polymer was coated on the cathode separator rather than the anode showed the best performance. This is considered to contribute to the extension of the life span by blocking the active material release from the anode rather than the anode. The overall conclusion is that the cell type coated with the gel polymer exhibits excellent battery performance as a large capacity battery with a retention capacity of 350 cycles and 75% retention capacity at 80% DOD.

Claims (4)

(a) fabricating two Ni strips whose surfaces have been perforated in a U-shaped concavo-convex shape, and then making them into a pocket shape in which insertion holes are formed to oppose each other; (b) uniformly filling the prepared active material into the interior of the insertion hole; (c) applying an external force to the metal plate to bring the two metal plates into contact with the encapsulated negative electrode or the positive electrode active material; (d) inserting the strips into a gap between the lug protruding outwardly from the side beads and the side beads to form a plate; And (e) laminating the completed electrode plate alternately with a cathode, a separator, and an anode according to a battery capacity, assembling the assembly into a plate assembly, and connecting the polarizer terminal to an external terminal post; (f) filling the assembled electrode plate with electrolytic solution inside the case,
The anode active material may be a mixture of Ni (OH) ₂ , CoO and Carbon, or ZnO, AB, Ca (OH) ₂ , Bi ₂ O ₃ , Acrylic Binder, , AB, Acrylic, Ca (OH) ₂ , Bi ₂ O ₃ , PTFE, Binder b, Binder c, and CMC are used. The positive electrode active material according to claim 1, wherein the positive electrode active material contains 85 wt% of Ni (OH) ₂ , 7 wt% of CoO, 8 wt% of carbon, or 89.0 wt% of ZnO, 2.0 wt% ₂ 4.0 wt%, Bi ₂ O ₃ 3.0 wt%, and Acrylic Binder 2.0 wt%
Negative electrode active material for 84 to 90% by weight, based on the total weight of ZnO (S), AB 1.5 ~ 2 weight%, Acrylic 0 ~ 3% by _{weight, Ca (OH) 2 2 ~} 3% by weight, Bi ₂ O ₃ 3.5 ~ 4 to 4 wt%, PTFE 0 to 0.6 wt%, Binder b 0 to 2 wt%, Binder c 0 to 0.4 wt%, and CMC 0 to 1 wt% are used. The method for manufacturing a nickel-zinc pocket-type battery according to claim 1, wherein the surface of the negative electrode and the positive electrode or the separation membrane is coated with a polyacrylic acid partial potassium salt (PAAK) polymer solution. The method of claim 1, wherein the electrolyte is EG-EKNL (KOH: NaOH: LiOH = 3: 2: 1) saturated with ZnO.

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