CN115832204A - Large-diameter and large-capacity winding type cylindrical battery with punched positive plate and preparation method thereof - Google Patents

Abstract

The invention discloses a large-diameter, high-capacity winding cylindrical battery with perforated positive electrodes and a preparation method thereof, belonging to the technical field of secondary batteries. The gist of the technical solution of the present invention is: a large-diameter, large-capacity winding cylindrical battery with a positive electrode sheet perforated, including a cylindrical battery core wound by a positive electrode sheet, a negative electrode sheet, and a separator. through hole. The invention also specifically discloses a preparation method of the large-diameter, large-capacity winding cylindrical battery with the positive plate perforated. The cell structure of the present invention has a good ability to increase and store the electrolyte, and at the same time prevents the local accumulation of heat, so as to achieve a good heat dissipation effect, and can effectively improve or even avoid the problem of heat accumulation caused by high-current charging, not only It can improve the high-rate charge and discharge performance of the battery, and can be prepared into a large-diameter, large-capacity single cylindrical battery with a diameter of ≥60mm and a capacity of >100Ah or even >300Ah.

Description

A large-diameter, high-capacity winding cylindrical battery with perforated positive electrode sheet and its preparation method

technical field

The invention belongs to the technical field of secondary batteries, and in particular relates to a large-diameter and large-capacity winding cylindrical battery with perforated positive electrodes and a preparation method thereof.

Background technique

With the advancement of science and technology and the development of modern society, chemical power sources are playing an increasingly important role and are widely used in construction machinery, rail and road transportation, ships, communications, aviation, national defense, energy storage and people's daily life all aspects of life. At present, commercial chemical power sources mainly include lithium-ion batteries, lead-acid batteries, and alkaline nickel-based batteries (nickel-hydrogen batteries, nickel-cadmium batteries, iron-nickel batteries, and zinc-nickel batteries). In addition, there are sodium-ion batteries, lithium-sulfur batteries, zinc-ion batteries and other metal-ion batteries under development. These batteries can be divided into two categories: cylindrical batteries and square batteries according to their dimensions. Cylindrical batteries are widely used because of their high shell structural strength, high voltage resistance, good safety performance, the winding method of their batteries and high degree of automation. However, compared with larger soft-pack or square batteries, cylindrical batteries have the problem that the battery and capacity cannot be enlarged. For example, the largest cylindrical lithium-ion battery model on the market is lithium iron phosphate battery 60320, which has a diameter of 60mm and a length of 320mm, its maximum capacity can only be about 100Ah. If the diameter and capacity continue to increase, it will become more and more difficult for the electrolyte to enter the interior of the cell due to the increase in the number of winding turns, and the difficulty of electrolyte penetration of the diaphragm and pole pieces will become more and more serious, resulting in The electrical properties such as battery cycle life and charge and discharge rate are significantly reduced. At the same time, the heat dissipation performance is also deteriorated during high rate charge and discharge, which is prone to heat accumulation. In addition, as the battery is charged and discharged, the expansion of the electrode is easy to absorb the electrolyte soaked on the separator, causing the separator to dry out, and finally causing the battery to fail. Therefore, it is difficult to increase the size and capacity of the cylindrical battery of the existing structure. Due to the small capacity of cylindrical batteries, when used as a power battery, many cylindrical batteries are often combined in parallel and in series to form a battery pack. For example, the Tesla Model SP85D pure electric vehicle used to require 7104 18650 batteries, which undoubtedly increased Complexity, failure rate, and cost of battery management systems.

Contents of the invention

The technical problem solved by the present invention is to provide a large-diameter, large-capacity winding cylindrical battery with perforated positive electrode sheet and its preparation method. The positive electrode sheet is perforated by design, and then the negative electrode sheet-diaphragm-perforated positive electrode Sheet-diaphragm or perforated positive electrode sheet-diaphragm-negative electrode sheet-diaphragm wound in order to form a cylindrical cell. This kind of cell structure has a good ability to increase and store electrolyte, and at the same time, it can prevent the local accumulation of heat, so as to achieve a good heat dissipation effect, and can effectively improve or even avoid the problem of heat accumulation caused by high-current charging. Improve the battery's high-rate charge and discharge performance, and can be prepared into a large-diameter, large-capacity single cylindrical battery with a diameter of ≥60mm and a capacity of >100Ah or even >300Ah.

In order to solve the above technical problems, the present invention adopts the following technical scheme, a large-diameter, high-capacity winding cylindrical battery with a positive electrode sheet perforated, including a cylindrical battery core wound by a positive electrode sheet, a negative electrode sheet and a separator, and its characteristics In that: the positive electrode sheet is provided with a through hole.

It is further defined that the through hole on the positive electrode sheet is a circular hole, an oval hole, a polygonal hole or a special-shaped hole, and the through hole has a transparent area ≥ 3mm².

It is further defined that the maximum aperture of the circular hole on the positive electrode sheet near the core is 2mm, the maximum aperture of the circular hole on the positive electrode sheet at the far core end is 20mm, and the aperture of the circular hole on the positive electrode sheet in the middle area is between 2-20mm gradually from inside to outside. get bigger.

It is further defined that the number of through holes on the positive electrode sheet is ≥3.

The method for preparing a large-diameter, large-capacity winding cylindrical battery according to the present invention is characterized in that the specific steps are:

Step S1: Attach the positive active material and the negative active material to the surface of the metal foil or metal mesh belt by coating or pulping process, leave one side of the positive plate and the negative plate blank as tabs, and dry, roll, separate Cut into positive and negative electrodes of specified size and size;

Step S2: Through design and calculation, use punching equipment and molds to punch through holes with a specified size and quantity on the positive electrode sheet to form a perforated positive electrode sheet;

Step S3: Wind the perforated positive electrode sheet into a cylindrical cell on the winding machine in the order of negative electrode sheet-diaphragm-perforated positive electrode sheet-diaphragm or perforated positive electrode sheet-diaphragm-negative electrode sheet-diaphragm, and load the diameter φ> 60mm battery case;

Step S4: Connect the negative tab of the wound cylindrical cell to the bottom of the negative electrode case or one end of the battery case, and the positive tab to the cap or the other end of the battery, and dry in a vacuum drying oven to reach the specified water content index. Liquid injection, sealing and formation are completed in the dry box.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. In the large-diameter, large-capacity winding cylindrical battery of the present invention, the positive electrode sheet is punched, and then the positive electrode sheet and the negative electrode sheet are separated by a separator, and wound in order to form a cylindrical cell, so that the through hole of the positive electrode sheet can be Increase the retention of free electrolyte, which greatly improves the problem of poor conductivity of large-diameter, large-capacity wound cylindrical batteries caused by poor liquid. The internal penetration and circulation of the pole piece group; at the same time, it can increase the heat dissipation space and effectively eliminate safety problems such as fire and explosion caused by heat accumulation.

2. The large-diameter, large-capacity winding battery of the present invention can effectively delay the drying up of the electrolyte because it can add an appropriate amount of electrolyte, so as to achieve the purpose of prolonging the battery cycle life and preventing the premature termination of battery life.

3. The large-diameter, large-capacity winding battery of the present invention has high-rate charge-discharge performance. This is because the holes inside the cylindrical battery core can retain the electrolyte, ensure the electro-hydraulic volume of the pole piece and the diaphragm, and reduce the battery life. internal resistance, and reduce the beneficial changes brought about by heat build-up.

4. The large-diameter, large-capacity wound cylindrical battery of the present invention can be made into a large-capacity single cylindrical battery with a diameter φ≥60mm and a capacity >100Ah or even >300Ah.

5. The raw materials used in the battery of the present invention remain unchanged, and the production cost is hardly increased. Since the problems of heat accumulation and rate charge and discharge are effectively solved, it can be made into a large-capacity single battery, saving the cost of the battery case, accessories and materials . In addition, since multiple small-capacity batteries do not need to be connected in parallel, they can be directly made into large-capacity batteries according to needs and then connected in series, which greatly simplifies the battery management system (BMS).

Description of drawings

FIG. 1 is a schematic structural view of a perforated positive electrode sheet in Example 1 of the present invention;

Fig. 2 is a schematic structural view of a wound cell in Example 1 of the present invention;

Fig. 3 is an appearance view of a single battery in Example 1 of the present invention.

In the figure: 1-perforated positive electrode sheet, 2-diaphragm, 3-negative electrode sheet.

Detailed ways

The above-mentioned contents of the present invention are described in further detail below through the embodiments, but this should not be interpreted as the scope of the above-mentioned themes of the present invention being limited to the following embodiments, and all technologies realized based on the above-mentioned contents of the present invention all belong to the scope of the present invention.

Example 1

3.2V 230Ah lithium iron phosphate cylindrical battery

0.025 mm thick aluminum foil and 0.02 mm thick copper foil were respectively selected as the positive electrode current collector and the negative electrode current collector of the battery. The mass ratio of positive electrode ingredients is lithium iron phosphate powder: conductive graphite: polyvinylidene fluoride binder is 85:10:5, add an appropriate amount of N-methylpyrrolidone solvent, and mix in a vacuum mixer to form a uniform positive electrode active material slurry. The mass ratio of negative electrode ingredients is artificial graphite: acetylene black: SBR binder is 90:5:5, add an appropriate amount of deionized water, and mix in a vacuum mixer to form a uniform negative electrode active material slurry. Apply positive electrode active material slurry and negative active material slurry to the surface of aluminum foil and copper foil respectively, leave blank on the side of positive electrode sheet and negative electrode sheet as tabs, dry and roll, and then cut into specified width and The length of the positive plate, negative plate. Punch through holes with a diameter of 5 mm at intervals of 40 mm on the positive electrode sheet with a punching machine die. See Figure 1 for the punched positive electrode sheet. Use an automatic winding machine to wind the negative electrode sheet 3-diaphragm 2-perforated positive electrode sheet 1-diaphragm 2 in order to form a cylindrical battery cell. The cylindrical battery cell is shown in Figure 2. Put the cylindrical battery cell into a cylindrical steel shell with a diameter of 80mm and a length of 380mm. Spot weld the blank part of the negative plate on the bottom of the steel shell, and spot weld the blank part of the positive plate on the cap. Dry, inject liquid, seal and Formation to produce a 3.2V 230AH lithium iron phosphate high-capacity cylindrical battery, as shown in Figure 3. The tested battery capacity is 225AH (0.5C), and the working voltage is 3.2V.

Example 2

Preparation of 2.3V 350AH lithium titanate battery

A 0.025 mm thick aluminum foil and a 0.02 mm thick aluminum foil were respectively selected as the positive electrode current collector and the negative electrode current collector of the battery. The mass ratio of positive electrode ingredients is nickel-cobalt-manganese-lithium powder (523) powder: conductive graphite: polyvinylidene fluoride binder is 85:10:5, add an appropriate amount of N-methylpyrrolidone solvent, and mix in a vacuum mixer to form a uniform positive electrode Active substance slurry. The mass ratio of negative electrode ingredients is lithium titanate: acetylene black: SBR binder is 90:5:5, add an appropriate amount of deionized water, and mix in a vacuum mixer to form a uniform negative electrode active material slurry. The positive electrode active material slurry and the negative electrode active material slurry were coated on the surface of the aluminum foil respectively, and the positive electrode sheet and the negative electrode sheet were left blank as tabs. After drying and rolling, it is then cut into positive and negative electrodes of specified width and length. Punch through holes with a diameter of 10mm at every 40mm intervals on the positive electrode sheet with a punching machine die, and use an automatic winding machine to stack and wind the perforated positive electrode sheet-diaphragm-negative electrode sheet-diaphragm in sequence to form a cylindrical cell. Put the cylindrical battery cell into a cylindrical steel shell with a diameter of 108mm and a length of 380mm. Spot weld the blank part of the negative plate on the bottom of the steel shell, and spot weld the blank part of the positive plate on the cap. Dry, inject liquid, seal and Formation to produce a 2.3V 350Ah lithium titanate battery. The tested battery capacity is 348Ah (0.5C), and the working voltage is 2.3V.

Example 3

Preparation of 3.4V 120AH Na-ion battery

A 0.025 mm thick aluminum foil and a 0.02 mm thick copper foil were respectively selected as the positive electrode current collector and the negative electrode current collector of the battery. The mass ratio of the positive electrode ingredients is Na ₃ V ₂ (PO ₄ ) ₂ O ₂ F@C powder: conductive graphite: polyvinylidene fluoride binder is 85:10:5, add an appropriate amount of N-methylpyrrolidone solvent, in a vacuum mixer mixed into a homogeneous positive electrode active material slurry. The mass ratio of negative electrode ingredients is hard carbon: acetylene black: SBR binder is 90:5:5, add an appropriate amount of deionized water, and mix in a vacuum mixer to form a uniform negative electrode active material slurry. The positive electrode active material slurry and the negative electrode active material slurry are respectively applied to the surface of the aluminum foil and the copper foil, leaving blank on the side of the positive electrode sheet and the negative electrode sheet as tabs. After drying and rolling, it is cut into positive and negative electrodes of specified width and length. Punch through holes with a diameter of 3 mm on the positive electrode sheet with a punching machine die. Use an automatic winding machine to stack the negative electrode sheet-diaphragm-perforated positive electrode sheet-diaphragm in order to form a cylindrical cell, put the cylindrical cell into a cylindrical steel shell with a length of 75mm and a length of 320mm, and leave the blank place for the negative electrode to meet Welded on the bottom of the steel case, spot-welded on the cap at the blank part of the positive plate, dried, injected, sealed and formed to produce a 3.4V 120Ah sodium-ion battery. The tested battery capacity is 117Ah (0.5C), and the voltage is 3.4V.

Comparative example 1

3.2V 230AH lithium iron phosphate battery

The positive and negative electrode current collector base belts, the positive and negative electrode ingredients and the preparation of the slurry are the same as in Example 1. The positive electrode active material slurry and the negative electrode active material slurry are respectively coated on the surface of the aluminum foil and the copper foil, leaving blank on the side of the positive electrode sheet and the negative electrode sheet as tabs. After drying and rolling, it is cut into positive and negative electrodes of specified width and length, and the positive electrode sheet-diaphragm-negative electrode sheet-diaphragm is superimposed and wound into a cylindrical cell by an automatic winding machine. Put the cylindrical cell into a cylindrical shell of a specified size, spot-weld the blank part of the negative electrode sheet on the bottom of the steel shell, and spot-weld the blank part of the positive electrode sheet on the cap. After drying, liquid injection, sealing and chemical formation, the A 3.2V 230Ah lithium iron phosphate battery was obtained. The tested battery capacity is 185Ah (0.5C), and the working voltage is 3.2V.

Comparative example 2

Preparation of 2.3V 350AH lithium titanate battery

The positive and negative current collector base belts, the ingredients of the positive and negative electrodes, and the preparation of the slurry are the same as in Example 2. The positive electrode active material slurry and the negative electrode active material slurry are respectively coated on the surface of the aluminum foil and the copper foil, leaving blank on the side of the positive electrode sheet and the negative electrode sheet as tabs. After drying and rolling, it is then cut into positive and negative electrodes of specified width and length. Using an automatic winding machine, the positive electrode sheet-diaphragm-negative electrode sheet-diaphragm is stacked and wound into a cylindrical cell in sequence. Put the cylindrical cell into a cylindrical steel shell of a specified size, spot weld the blank part of the negative plate on the bottom of the steel shell, and spot weld the blank part of the positive plate on the cap, after drying, liquid injection, sealing and chemical formation, A 2.3V 350AH lithium titanate battery was prepared. The tested battery capacity is 310AH (0.5C), and the working voltage is 2.3V.

Comparative example 3

Preparation of 3.4V 120AH Na-ion battery

The positive and negative electrode current collector base belts, the positive and negative electrode ingredients and the preparation of the slurry are the same as in Example 3. The positive electrode active material slurry and the negative electrode active material slurry are respectively coated on the surface of the aluminum foil and the copper foil, leaving blank on the side of the positive electrode sheet and the negative electrode sheet as tabs. After drying and rolling, it is then cut into positive and negative electrodes of specified width and length. Use an automatic winding machine to superimpose and wind the negative electrode sheet-diaphragm-positive electrode sheet-diaphragm into a cylindrical cell, put the cylindrical cell into a cylindrical steel shell of a specified size, and spot weld the blank part of the negative electrode sheet at the bottom of the steel shell. The blank part of the positive plate is collected and spot-welded on the cap, and after drying, liquid injection, sealing and chemical formation, a 3.4V 120AH sodium ion soft pack battery is produced. The tested battery capacity is 114AH (0.5C), and the voltage is 3.4V.

Table 1 Comparison of battery performance

Through Examples 1-3 and Comparative Examples 1-3, it can be seen that the wound cylindrical battery of the present invention is punched through the positive electrode sheet, so that a small amount of free electrolyte can be retained in the through hole, which greatly improves the wound cylindrical battery. Due to the poor conductivity of the battery caused by poor liquid, the through holes inside the wound cylindrical battery can promote the electrolyte to penetrate inside the battery pole piece group, effectively eliminating heat accumulation, and can be prepared with a diameter greater than 60mm and a capacity greater than 100Ah or even 300Ah large-capacity single cylindrical battery, and due to the good heat dissipation effect, the battery temperature rise is low, and it has excellent high-rate charge-discharge performance and excellent cycle performance.

The basic principles, main features and advantages of the present invention have been shown and described above. On the premise of not departing from the spirit and scope of the present invention, the present invention also has various changes and improvements, and these changes and improvements all fall into the claimed invention. range.

Claims (5)

1. The utility model provides a major diameter, the large capacity coiling formula cylinder battery that positive plate punched, includes the cylinder electricity core that forms by positive plate, negative pole piece and diaphragm coiling, its characterized in that: and the positive plate is provided with a through hole.

2. The positive electrode sheet perforated large-diameter, large-capacity wound cylindrical battery according to claim 1, characterized in that: the through hole on the positive plate is a circular hole or an elliptical hole, and the transparent area of the through hole is more than or equal to 3 mm.

3. The positive electrode sheet perforated large-diameter, large-capacity wound cylindrical battery according to claim 1, characterized in that: the maximum aperture of the circular hole on the positive plate at the near core end is 2mm, the maximum aperture of the circular hole on the positive plate at the far core end is 20mm, and the aperture of the circular hole on the positive plate at the middle area is gradually increased from inside to outside within 2-20 mm.

4. The positive electrode sheet perforated large-diameter, large-capacity wound cylindrical battery according to claim 1, characterized in that: the number of the through holes on the positive plate is more than or equal to 3.

5. A method for preparing a large-diameter, large-capacity wound cylindrical battery according to any one of claims 1 to 4, characterized by comprising the specific steps of:

step S1: coating or slurry drawing process is adopted to attach the positive electrode active substance and the negative electrode active substance on the surface of the metal foil or the metal mesh belt, one side surface end of the positive electrode sheet and the negative electrode sheet is left white as a tab, and the positive electrode sheet and the negative electrode sheet are dried, rolled and cut into positive electrode sheets and negative electrode sheets with specified sizes and dimensions;

step S2: punching through holes with the size and the number specified by the process on the positive plate by using punching equipment and a die for designing and calculating to form a punched positive plate;

and step S3: winding the punched positive plate into a cylindrical battery cell on a winding machine according to the sequence of negative plate-diaphragm-punched positive plate-diaphragm or punched positive plate-diaphragm-negative plate-diaphragm, and packaging into a battery shell with the diameter phi of more than or equal to 60 mm;

and step S4: the cylindrical battery core negative electrode lug that will convolute converges at negative pole shell bottom or battery case's one end, and positive electrode lug converges at the other end of block or battery, puts into the drying cabinet of vacuum drying, reaches the water content index of regulation, accomplishes the notes liquid in the drying cabinet incasement, seals and forms with changing.

Images