CN102082302A - Nickel hydrogen secondary battery - Google Patents

Abstract

The invention provides a nickel-hydrogen secondary battery, which belongs to the field of nickel-hydrogen batteries. The battery includes a battery casing, an electrode group and an alkaline electrolyte, and the electrode group and the alkaline electrolyte are sealed in the battery casing. The electrode group includes a positive electrode, a negative electrode and a separator, and is characterized in that the alkaline electrolyte is a gel electrolyte, and the gel electrolyte includes carboxymethyl cellulose, alkali metal hydroxide and water. The electrolytic solution of the Ni-MH battery provided by the invention is not easy to freeze at low temperature, has little loss of electrolytic solution during long-term use, does not cause leakage at high current, and has good low-temperature discharge performance.

Description

A nickel metal hydride secondary battery

technical field

The invention relates to a secondary battery, in particular to a nickel-hydrogen secondary battery. the

Background technique

In recent years, due to the development of portable electronic devices and the revolution of transportation power energy, the research and development of high-energy battery energy has become the focus of academic circles and industrial revolutions all over the world. Nickel-metal hydride secondary batteries have been widely valued because of their advantages such as high energy, good safety, no pollution, and no memory effect. They are one of the main types of power supply batteries for electronic equipment. the

At present, the electrolyte of nickel-metal hydride secondary batteries is mainly concentrated KOH aqueous solution, but when using concentrated KOH aqueous solution as the electrolyte of nickel-hydrogen batteries, the electrolyte will freeze when used at lower temperatures, and it can no longer be charged and discharged, resulting in the failure of nickel-hydrogen batteries. Low temperature discharge efficiency is low. the

Contents of the invention

The technical problem to be solved by the present invention is the defect of the low-temperature discharge efficiency of the electrolyte of the existing nickel-hydrogen secondary battery, thereby providing a nickel-hydrogen secondary battery with high low-temperature discharge efficiency. the

The invention provides a nickel-hydrogen secondary battery, which comprises a battery case, an electrode group and an alkaline electrolyte, the electrode group and the alkaline electrolyte are sealed in the battery case, and the electrode group includes a positive pole, a negative pole And separator, wherein, the alkaline electrolyte is a gel electrolyte, the gel electrolyte includes carboxymethyl cellulose, alkali metal hydroxide and water. the

In the nickel-hydrogen secondary battery of the present invention, the electrolyte of the battery contains carboxymethyl cellulose, because carboxymethyl cellulose has good water absorption, when carboxymethyl cellulose absorbs a large amount of water in the electrolyte The water will form a gel electrolyte, because the alkali metal hydroxide is dissolved in water, so can be very uniformly dispersed in the gel formed by carboxymethyl cellulose, the nickel-hydrogen secondary battery of the present invention overcomes the concentrated Potassium hydroxide is used as the electrolyte to freeze the liquid electrolyte, and at the same time it solves the problem that the electrolyte is easy to dry up and leak when concentrated potassium hydroxide is used as the electrolyte. Thereby, the low-temperature discharge performance of the battery and the safety, reliability and durability of the nickel-metal hydride battery are further improved. the

Detailed ways

The invention provides a nickel-hydrogen secondary battery, which comprises a battery case, an electrode group and an alkaline electrolyte, the electrode group and the alkaline electrolyte are sealed in the battery case, and the electrode group includes a positive pole, a negative pole And separator, wherein, the alkaline electrolyte is a gel electrolyte, the gel electrolyte includes carboxymethyl cellulose, alkali metal hydroxide and water. the

Because carboxymethyl cellulose has good water absorption, when carboxymethyl cellulose absorbs a large amount of water in the electrolyte, it will form a gel electrolyte. Since the alkali metal hydroxide is dissolved in water, it can Very uniform dispersion of carboxymethyl cellulose in the gel. It overcomes the problems of liquid electrolyte freezing, dryness and leakage caused by concentrated sodium hydroxide as the electrolyte, thereby further improving the low-temperature discharge performance, safety, reliability and durability of the nickel-metal hydride battery. Simultaneously, the raw material of the electrolytic solution of the present invention is simple and cheap, can reduce the cost of nickel-metal hydride battery production. After using the electrolyte of the present invention, the requirements for the diaphragm are reduced, and a cheap diaphragm can be used to reduce the cost. the

According to the nickel-hydrogen secondary battery provided by the present invention, preferably, based on the weight of the electrolyte, the content of the carboxymethyl cellulose is 1.0-4.0 wt%, and the content of the hydroxide of the alkali metal is The content is 35-45wt%. the

According to the nickel-hydrogen secondary battery provided by the present invention, the alkali metal hydroxide may be various alkali metal hydroxides known to those skilled in the art, preferably sodium hydroxide and/or potassium hydroxide. the

According to the nickel-metal hydride secondary battery provided by the present invention, in order to improve the conductivity of the electrolyte, preferably, the electrolyte further includes zinc oxide. the

According to the nickel-hydrogen secondary battery provided by the present invention, the content of zinc oxide is not particularly limited, as long as the conductivity of the electrolyte can be mentioned, in order to improve the conductivity of the electrolyte, at the same time try to Without wasting materials and without affecting the capacity of the battery, preferably, based on the weight of the electrolyte, the content of the zinc oxide is 0.5-1.5 wt%. the

According to the nickel-metal hydride secondary battery of the present invention, wherein, the electrolytic solution can form a gel before being injected into the battery, and can also form a gel after being injected into the battery. In order to facilitate battery assembly, it is preferable to form a gel after being injected into the battery. . The method for forming the gel is to allow the electrolyte solution containing the above-mentioned components to stand for a period of time, as long as the carboxymethyl cellulose can fully absorb the water in the electrolyte solution. the

According to the nickel-hydrogen secondary battery provided by the present invention, the preparation method of the gel electrolyte is as follows: dissolve carboxymethyl cellulose in water, then slowly add alkaline hydroxide, stir continuously until it is completely dissolved, and then inject In NiMH batteries, the electrolyte forms a gel electrolyte in the battery. the

In addition to the electrolyte, the nickel-hydrogen secondary battery of the present invention may have other structures known to those skilled in the art for nickel-hydrogen secondary batteries. the

According to the nickel-metal hydride secondary battery provided by the present invention, the separator is arranged between the positive electrode and the negative electrode, it has electrical insulation performance and electrolyte retention performance, and allows the electrode group and the alkaline electrolyte to be contained together in the battery in the shell. The separator can be selected from various separators used in alkaline secondary batteries, such as polyolefin fiber non-woven fabric with hydrophilic fibers or sulfonated sheet-like components introduced into the surface. The location, nature and type of said separators are well known to those skilled in the art. the

The positive electrode can be selected from the positive electrodes used in various nickel-hydrogen secondary batteries, which are commercially available or prepared by existing methods. The positive electrode conductive substrate is a positive electrode conductive substrate commonly used in nickel-metal hydride secondary batteries, such as a nickel foam substrate, a substrate with a felt sheet structure, a metal perforated plate or a porous drawn metal mesh. the

The positive electrode material of the nickel-metal hydride secondary battery contains nickel hydroxide and a binder, and the binder can be the binder used in the negative electrode. For example, the binder used for the positive electrode can be selected from one or more of carboxymethylcellulose, hydroxypropylmethylcellulose, methylcellulose, sodium polyacrylate, polytetrafluoroethylene and polyvinyl alcohol. kind. The content of the binder is well known to those skilled in the art, generally based on the positive electrode active material nickel hydroxide, the content of the positive electrode binder is 0.01-5% by weight, preferably 0.02-3% by weight. the

The preparation method of the positive electrode can adopt conventional preparation methods. For example, the positive electrode can be obtained by mixing the nickel hydroxide, binder and solvent into a paste, coating and/or filling on the conductive substrate, drying, and compression molding or not. Wherein, the solvent can be selected from any solvent capable of making the mixture form a paste, preferably water. The amount of the solvent can make the paste have viscosity and can be coated on the conductive substrate. Generally, the content of the solvent is 15-40% by weight of the nickel hydroxide, preferably 20-35% by weight. Wherein, the methods and conditions of drying and compression molding are well known to those skilled in the art. the

The negative electrode can be selected from negative electrodes used in various nickel-hydrogen secondary batteries, which can be obtained commercially or prepared by existing methods. The composition of the negative electrode material is known to those skilled in the art. Generally, the negative electrode material contains a main component and a binder, and the main component is a hydrogen storage alloy. The hydrogen storage alloy can be selected from any hydrogen storage alloy that can be used as the main component of the negative electrode of the alkaline secondary battery, and the hydrogen storage alloy can absorb the hydrogen generated by the alkaline electrolyte in the electrochemical reaction, and when discharging Absorbed hydrogen can be decomposed reversibly. The commonly used hydrogen storage alloy is AB ₅ .

The type and content of the binder are known to those skilled in the art, for example, the binder can be selected from carboxymethylcellulose, hydroxypropylmethylcellulose, methylcellulose, sodium polyacrylate, One or several types of polytetrafluoroethylene; generally speaking, according to the type of adhesive used, the content of the adhesive is 0.01-5% by weight of the main component, preferably 0.02-3% by weight. the

The negative electrode material may also contain additives, and the types and contents of additives are known to those skilled in the art. For example, the additive is selected from one or more of graphite, carbon black, nickel powder, cobalt powder and the like. Generally, the content of the additive is 0.1-15% by weight of the main component, preferably 0.5-10% by weight. the

The negative electrode sheet can be prepared by a preparation method known in the art. For example, the negative electrode sheet can be obtained by mixing the negative electrode material and the solvent to obtain the negative electrode slurry, and then coating and/or filling the negative electrode slurry on the negative electrode conductive substrate, drying, and compression molding or not. Among them, the solvent is preferably water. The amount of the solvent can make the negative electrode slurry have viscosity and fluidity, and it only needs to be able to be coated on the negative electrode conductive substrate. Generally, the content of the solvent is 10-30% by weight of the main component, preferably 15-25% by weight. Wherein, the methods and conditions of drying and compression molding are well known to those skilled in the art. the

According to the preparation method of the nickel-metal hydride secondary battery provided by the present invention, except that the alkaline electrolyte is the nickel-hydrogen battery electrolyte provided by the present invention, other steps are well known to those skilled in the art. Generally speaking, a separator is arranged between the prepared positive electrode and the negative electrode to form an electrode group, the electrode group is accommodated in a battery case, an electrolyte is injected, and the battery case is sealed to obtain the present invention. The alkaline secondary battery provided by the invention. the

The present invention will be described in more detail below by way of examples. the

Example 1

(1) Making the positive electrode

Mix nickel hydroxide, CoO, Ni, carboxymethyl cellulose and water with a weight ratio of 60:4:8:3:25 and stir evenly to make positive electrode slurry, and coat the slurry on a surface with a size of 184 mm × 24 mm x 1.5 mm nickel mesh. Scrape off the slurry at a distance of 40 mm from one end of the nickel mesh in the length direction, and press it into a positive electrode sheet with a size of 184 mm×24.5 mm×0.6 mm. After the nickel mesh is pressed, spot-weld the positive tab at the place where the material is scraped. The positive tab is a nickel-plated steel strip, rectangular in shape, 28.5 mm long, 7.0 mm wide, and 0.12 mm thick. Wherein, the positive electrode contains 8.8 grams of nickel hydroxide. the

(2) Making the negative electrode

Mix and stir hydrogen storage alloy powder, hydroxypropyl methylcellulose and water with a weight ratio of 85:6:9 to make negative electrode slurry, and coat the slurry on a steel plate with a size of 240 mm × 24.8 mm × 0.6 mm. bring. Scrape off the slurry at a distance of 40 mm from one end of the steel strip in the length direction, and press it into a negative electrode sheet with a size of 242 mm×24.8 mm×0.3 mm. After the steel strip is pressed into pieces, spot weld the negative electrode lug at the place where the material is scraped. The negative electrode lug is a nickel-plated steel strip, including a rectangular welding part 1 and a circular contact part 2. The length of the welding part 1 is 8 mm, the width is 7 mm, and the diameter of the contact part 2 is 20.5 mm. The thickness is 0.12 mm. Wherein, the negative electrode contains 9.6 grams of hydrogen storage alloy powder. the

(3) Assemble the battery

The positive electrode and negative electrode prepared in (1) and (2) and the sulfonated polypropylene separator (area density 60 g/m2, thickness 0.12 mm) were wound and put into the battery case. the

(4) Electrolyte preparation

Put 2.4 grams of carboxymethyl cellulose and 56.1 grams of water into the beaker, and after stirring for 20 minutes, slowly add 40 grams of potassium hydroxide into the beaker, and stir for 20 minutes until the temperature of the beaker is cooled; One gram of zinc oxide was added in the electrolytic solution, and then stirred for 20 minutes after adding, until the complete dissolution of the zinc oxide obtained the electrolytic solution A1 of the present embodiment. the

(5) Packaging

Inject the electrolyte solution A1 into the battery in step (3), and seal it to make a nickel-metal hydride battery B1. the

Example 2

Ni-MH battery B2 was prepared according to the same method as in Example 1, the difference was that 4.0 grams of carboxymethyl cellulose and 51 grams of water were put into a beaker during the preparation of the electrolyte, and 45 grams of hydrogen Potassium oxide was slowly added into the beaker and stirred for 20 minutes until the temperature of the beaker was cooled to obtain the electrolyte A2 of this embodiment. the

Example 3

Ni-MH battery B3 was prepared in the same manner as in Example 1. The difference was that 1.0 g of carboxymethyl cellulose and 63.9 g of water were put into a beaker during the preparation of the electrolyte, and 35 g of hydrogen was added after stirring for 20 minutes. Slowly add potassium oxide into the beaker, stir for 20 minutes, until the temperature of the beaker is cooled; under the condition of stirring, add 0.1 g of zinc oxide into the electrolyte, and stir for another 20 minutes until the zinc oxide is completely dissolved to obtain Electrolyte A3 of this embodiment. the

Example 4

Ni-MH battery B4 was prepared in the same manner as in Example 1. The difference was that 3.0 grams of carboxymethyl cellulose and 58 grams of water were put into a beaker during the preparation of the electrolyte, and 38 grams of hydrogen Slowly add potassium oxide into the beaker, stir for 20 minutes, until the temperature of the beaker cools down; under the condition of stirring, add 1.0 g of zinc oxide into the electrolyte solution, and stir for another 20 minutes until the zinc oxide is completely dissolved to obtain Electrolyte A4 of this embodiment. the

Comparative example 1

Prepare battery according to the method identical with embodiment 1, difference is, electrolyte solution is the KOH of 7mol/L, makes nickel metal hydride battery C1. the

Test Methods

1. Discharge the batteries B1-B4 and C1 in Examples 1-4 and Comparative Example 1 at -10°C, -20°C, and -30°C respectively at 0.2C. The results are shown in Table 1. the

Table 1

Electrolyte Type -10℃ discharge efficiency (%) -20℃ discharge efficiency (%) -30℃ discharge efficiency (%) B1 93 74 31 B2 94 74 33 B3 93.5 72 30 B4 94 73 31 C1 84 68 twenty two

2. Test the internal resistance of batteries B1-B4 and C1 in Examples 1-4 and Comparative Example 1, the results are shown in Table 2. the

Table 2

Electrolyte type Battery 1 internal resistance (milliohms) Battery 2 internal resistance (milliohms) Battery 3 internal resistance (milliohms) Average internal resistance (milliohms) B1 16 16.2 16.1 16.1 B2 15.8 15.7 15.8 15.8 B3 15.5 15.7 15.6 15.6 B4 15.4 15.2 15.6 15.4 C1 15.4 15.7 15.5 15.5

As can be seen from Table 1, the discharge efficiency of the nickel-hydrogen battery using the nickel-hydrogen battery electrolyte of the present invention is greater than 93% at-10°C, the discharge efficiency at-20°C is greater than 72%, and the discharge efficiency at-30°C is greater than 30%. , while the discharge efficiencies of the comparative examples were 84%, 68% and 22%, so the Ni-MH battery using the electrolyte of the present invention has good low-temperature discharge performance. It can be seen from Table 2 that the average internal resistance of the Ni-MH battery assembled from the electrolyte without zinc oxide in the electrolyte is significantly higher than the average internal resistance of the Ni-MH battery assembled from the electrolyte with zinc oxide in the electrolyte Large, so zinc oxide can increase the conductivity of the battery. the

Claims (6)

1. a nickel-metal hydride secondary battery, this battery comprises battery case, electrode group and alkaline electrolyte, described electrode group and alkaline electrolyte are sealed in battery case, and described electrode group comprises positive pole, negative pole and separator The plate is characterized in that the alkaline electrolyte is a gel electrolyte, and the gel electrolyte includes carboxymethyl cellulose, alkali metal hydroxide and water. 2. The nickel-metal hydride secondary battery according to claim 1, characterized in that, based on the weight of the gel electrolyte, the content of the carboxymethyl cellulose is 1.0-4.0 wt%. 3. The nickel-metal hydride secondary battery according to claim 1, characterized in that, based on the weight of the gel electrolyte, the content of the alkali metal hydroxide is 35-45 wt%. 4. The nickel-metal hydride secondary battery according to claim 1, wherein the hydroxide of the alkali metal is sodium hydroxide and/or potassium hydroxide. 5. The nickel-metal hydride secondary battery according to any one of claims 1-4, further comprising zinc oxide. 6. The nickel-metal hydride secondary battery according to claim 5, wherein, based on the weight of the electrolytic solution, the content of the zinc oxide is 0.5-1.5 wt%.