CN202495524U - Irregular lithium ion battery - Google Patents

Abstract

The utility model belongs to the technical field of lithium-ion batteries, in particular to a special-shaped lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and a package film, the positive electrode sheet is provided with positive electrode sheet punching holes, and the negative electrode sheet is provided with negative electrode sheet punching holes There are diaphragm punching holes on the diaphragm. After the positive electrode sheet, diaphragm and negative electrode sheet are wound or laminated to make the battery core, the centers of the positive electrode sheet punching hole, negative electrode sheet punching hole and diaphragm punching hole are all on the same On a straight line, a connected gap is formed. Compared with the prior art, the special-shaped lithium-ion battery of the utility model increases the channel for electrolyte absorption because of the holes, promotes the absorption of the electrolyte by the pole piece, improves the infiltration of the electrolyte on the pole piece, and improves the lithium-ion battery. At the same time, the utility model also solves the problem that the traditional lithium-ion battery cannot meet the power supply requirements of special-shaped electronic products.

Description

A special-shaped lithium-ion battery

technical field

The utility model belongs to the technical field of lithium ion batteries, in particular, the utility model relates to a special-shaped lithium ion battery.

Background technique

Due to the advantages of high energy density, environmental protection and long cycle life, lithium-ion batteries have been widely used in mobile devices (such as MP3, mobile phones, notebook computers), electric vehicles, military and aerospace.

With the rapid development of electronic technology, market competition is becoming increasingly fierce. The quality of electronic products is getting lighter and thinner, which puts forward higher and higher requirements for the energy density of batteries. In addition, due to the development of electronic technology and the improvement of raw material production technology, the service life of electronic products is getting longer and longer, so the requirements for the cycle life of lithium-ion batteries are also getting higher and higher. Improving the service life of lithium-ion batteries can not only reduce the cost of using batteries, but also reduce the scrap rate of lithium-ion batteries, which can truly be environmentally friendly.

The service life of traditional lithium-ion batteries is generally 300 cycles to 500 cycles, and the current electronic products have more and more functions, resulting in faster discharge during use, especially for current smartphones and notebook batteries. There are many procedures, and the battery should be charged at least once a day. In this way, for traditional lithium-ion batteries, the service life of the corresponding electronic products is basically one to one and a half years. This greatly increases the use cost of the end user, and is also not conducive to environmental protection.

The main factors affecting the cycle life of lithium-ion batteries are: the type of positive and negative active materials, the type of electrolyte and the amount of electrolyte absorption, process parameters (such as compaction density), charging and discharging conditions, and the environment in which lithium-ion batteries are used. When the positive and negative active materials, charge and discharge conditions, and the use environment are determined, the main factor affecting the cycle life of lithium-ion batteries is the absorption of electrolyte. One of the factors affecting the absorption of electrolyte is the amount of electrolyte perfusion, and the other is the compaction density of the positive and negative electrodes. The size of the compaction density affects the porosity of the pole piece, which in turn affects the absorption of the electrolyte by the pole piece. During the use of lithium-ion batteries, due to side reactions, the electrolyte will be consumed on the surface of the positive and negative electrodes, resulting in a decrease in the amount of electrolyte inside the lithium-ion battery. At the same time, the side reactions will increase the interface impedance of the battery, so lithium The cycle life of ion batteries will decay, especially in the later stage of electrolyte consumption, the impedance will increase faster, and the cycle life decay will also accelerate.

Traditional lithium-ion batteries achieve long cycle life by reducing the compaction density of the positive and negative electrodes. The advantage of this is that by reducing the compaction density, the porosity of the pole piece is increased, and the absorption of the electrolyte by the pole piece is increased to ensure Lithium-ion batteries have enough electrolyte inside to increase cycle life. However, when the compaction density of the positive and negative electrodes is too low, it will lead to poor contact between particles, especially during the use of lithium-ion batteries, the internal collision of the pole piece will worsen the contact between particles, so that lithium is deposited on the surface of the negative electrode during charging, and discharge When the rate performance becomes worse, it also makes the battery cycle worse. In the actual production process, due to the influence of equipment precision and process control level, such as low coating weight and low pressure of cold pressing equipment, it may lead to low compaction density of some pole pieces, resulting in poor battery cycle. It may even cause the battery to decompose lithium, which in turn affects battery safety.

In addition, in order to improve the competitiveness of electronic products, some consumer electronic products have been transformed into special shapes, and the shapes of electronic products are becoming more and more diverse. For example, bluetooth earphones in the shape of bananas, round MP3 players, round mobile phones, ring-shaped electronic wristwatches, square electronic clocks embedded with transparent round electronic displays, etc. The shape of traditional lithium-ion batteries is mostly cuboid or cylinder. In general, in order to meet the needs of special-shaped electronic products, when the energy density of a traditional-shaped battery cannot meet the requirements of electronic products, battery designers will use it according to the shape of electronic products. In order to meet the charging and discharging requirements of this shape product, design batteries of corresponding size in the appropriate part of this electronic product and connect them in parallel. For this kind of electronic products, the consequence of using multiple batteries in parallel is to directly lead to a serious decrease in the utilization rate of the internal space of the electronic product, especially the increase in the product grouping process, which will greatly increase the production cost of the battery. Therefore, it is necessary to provide a new manufacturing method for lithium-ion batteries to meet the above-mentioned requirements for batteries with special shapes.

In view of this, it is necessary to provide a special-shaped lithium-ion battery with a long cycle life.

Utility model content

The purpose of the utility model is to provide a special-shaped lithium-ion battery with a long cycle life in view of the deficiencies of the prior art.

In order to achieve the above object, the utility model adopts the following technical solutions:

A special-shaped lithium ion battery, comprising a positive electrode sheet, a negative electrode sheet, a diaphragm and a packaging film, the positive electrode sheet is provided with a positive electrode sheet punching hole, the negative electrode sheet is provided with a negative electrode sheet punching hole, and the diaphragm is provided with a diaphragm punching hole, and the positive electrode sheet is provided with a punching hole for the positive electrode sheet. After the sheet, diaphragm and negative electrode sheet are wound or stacked to form a battery cell, the centers of the punched hole of the positive electrode sheet, the punched hole of the negative electrode sheet and the punched diaphragm all fall on the same straight line, forming a connected gap.

Compared with the prior art, the special-shaped lithium-ion battery of the utility model increases the channel for electrolyte absorption due to the existence of punching holes, promotes the absorption of the electrolyte by the pole piece, improves the infiltration of the electrolyte solution on the pole piece, and the internal The resistance is significantly reduced, and the cycle performance of the lithium-ion battery is improved.

As an improvement of the special-shaped lithium-ion battery of the utility model, the punching holes of the positive electrode sheet, the negative electrode sheet and the diaphragm are respectively set in the central area or the edge area of the battery cell.

As an improvement of the special-shaped lithium-ion battery of the utility model, the shapes of the punched hole of the positive electrode sheet, the punched hole of the negative electrode sheet and the punched diaphragm are circular, square, triangular or trapezoidal.

As an improvement of the special-shaped lithium-ion battery of the utility model, the encapsulation film is provided with an encapsulation film punching hole, and the center of the encapsulation film punching hole and the cell punching hole fall on the same straight line.

As a kind of improvement of the special-shaped lithium-ion battery of the present invention, the diameter or side length of punching hole of positive electrode sheet, negative electrode sheet, diaphragm punching and packaging film is greater than or equal to 0.1 μm, but less than the width of the electrode sheet, with Ensure that the pole piece can be wound normally without breaking.

Compared with the prior art, the special-shaped lithium-ion battery of the utility model solves the problem that the traditional lithium-ion battery cannot meet the power supply requirements of special-shaped electronic products, especially electronic products where the battery is placed with protrusions or parts that need to be hollowed out. The adoption of the lithium ion battery of the utility model solves the problem that multiple batteries need to be connected in parallel due to irregular shapes of electronic products (such as local protrusions). On the premise of satisfying the capacity of electronic products, the utility model greatly reduces the production quantity of lithium ion batteries and improves the production efficiency of lithium ion batteries. From the perspective of process efficiency, the utility model replaces multiple batteries with one battery, reduces the number of batteries, improves the efficiency of the packaging process and electrolyte perfusion process, cancels the grouping process of batteries, and improves the utilization of chemical formation equipment and capacity testing equipment Rate. Therefore, the production cost of the lithium-ion battery of the utility model is greatly reduced, which provides a strong guarantee for the wide application of the lithium-ion battery. At the same time, it also provides a strong condition for the diversification of electronic products, which can more widely meet people's daily needs for electronic products. In addition, the lithium-ion battery of the present utility model has a recessed design or a hollow design locally, and the lithium-ion battery can also play a role of fixing the battery by matching the corresponding recessed or hollowed out part with the shape of the electronic product. Placing the battery inside the electronic product to shift or shake can protect the edges and corners of the battery from being damaged, and reduce the chance of internal short circuit of the battery due to the extrusion of the corners.

Description of drawings

The utility model and its beneficial technical effects are described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein:

Fig. 1 is a schematic diagram of a special-shaped lithium-ion battery with a cylindrical hollow in the middle of the utility model;

Fig. 2 is a schematic diagram of a special-shaped lithium-ion battery with a rectangular notch on the side of the utility model;

Fig. 3 is a schematic diagram of a special-shaped lithium-ion battery with an arc-shaped gap on the corner of the utility model;

Fig. 4 is a schematic diagram of a special-shaped lithium-ion battery with partial depressions of the present invention.

Detailed ways

Specific implementation mode 1

The first point that needs to be explained is that before the preparation, the size of the positive electrode, negative electrode and diaphragm used in the lithium-ion battery is calculated according to the capacity requirements;

When punching, it is necessary to punch out according to the calculation results and battery size requirements, so as to punch out the required punching size and shape.

Positive electrode sheet preparation: LiCoO ₂ (lithium cobaltate), superconducting carbon (Super-P), polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a mass ratio of 95.0:2.5:2.5, mixed and stirred Evenly, a slurry with a certain fluidity is obtained, and then the obtained slurry is coated on both sides of a 16um thick metal aluminum foil, and dried to form a pole piece with a certain degree of softness. Then cold press, slitting, and after slitting, punch the electrode sheet corresponding to each layer of the battery cell to obtain the positive electrode sheet punching. The shape of the hole is circular and the diameter of the hole is 15mm. The positive electrode tab made of the sheet is welded on the aluminum foil to make the positive electrode sheet.

Negative sheet preparation: add graphite, superconducting carbon (Super-P), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) in deionized water according to the mass ratio of 95.5:1.5::1.5:1.5 and mix Stir evenly to obtain a slurry with a certain fluidity, and then coat the above slurry on both sides of a 12um thick metal copper foil, and dry it to form a pole piece with a certain flexibility. Then cold pressing and slitting (i.e., cutting and cutting the negative electrode sheet into the required size), and then punching holes in the position of each layer of the battery cell corresponding to the electrode sheet to obtain the punching hole of the negative electrode sheet. The shape of the hole is a circle. shape, the diameter of the hole is 13 mm, and then the negative electrode tab made of 0.4 mm thick copper sheet is welded on the copper foil to make the negative electrode sheet.

Diaphragm preparation: The diaphragm can be made of polypropylene (PP)-polyethylene (PE)-polypropylene PP three-layer composite film, and punch holes corresponding to each layer of the cell to obtain a diaphragm punch. The shape of the hole is circular, and the hole The diameter is 10mm.

Packaging film preparation: The packaging film is made of aluminum-plastic composite film, and its structure is nylon-aluminum foil-polypropylene from the outside to the inside. The encapsulating film is punched up and down to obtain the encapsulating film punched, the shape of the hole is circular, and the diameter of the hole is 7mm.

The centers of the punched holes of the above positive electrode sheet, negative electrode sheet, diaphragm, and packaging film are all on the same center line, so as to ensure that the center positions of all holes coincide after packaging.

The prepared positive electrode sheet, negative electrode sheet and separator are laminated or wound to form a battery cell, and then the battery cell is put into the battery packaging case for packaging process. After heat packaging, electrolyte solution is injected into the battery, and lithium hexafluorophosphate ( LiPF ₆ ) is lithium salt, with 20% ethylene carbonate, 30% ethyl methyl carbonate and 50% dimethyl carbonate as solvent, wherein, the concentration of lithium hexafluorophosphate is 1M, and then through chemical formation, aging and other processes Get finished batteries. The middle of the prepared lithium-ion battery is a cylindrical hollow, as shown in FIG. 1 .

For this kind of lithium-ion battery with a hollow structure, when packaging; in addition to top sealing and side sealing, the hollow position in the middle should also be packaged.

Specific implementation mode 2

The difference from Embodiment 1 is that, before coating, punch holes are made on the positive electrode collector and the negative electrode collector, and then the subsequent coating, cold pressing and slitting operations are carried out. The shape of the punched hole is a rectangle, the length of the rectangle is 10mm, and the width is 5mm. The encapsulation film is not punched, and the other processes are the same as in the specific embodiment 1. There is a rectangular notch on the side of the prepared lithium-ion battery, as shown in FIG. 2 .

Specific implementation mode 3

The difference from the specific embodiment 2 is that the positive electrode plate punching, the negative electrode plate punching, and the diaphragm punching are arc-like in shape, the packaging film is not punched, and other processes are the same as in the specific embodiment 1. The obtained lithium ion battery There is an arc-shaped notch on the corner, as shown in Figure 3.

Specific implementation mode 4

The difference from Embodiment 1 is that the punching diameter of the positive electrode sheet is 1 mm, the diameter of the punching hole of the negative electrode sheet is 0.5 mm, the diaphragm is not punched, the packaging film is not punched, and other processes are the same as in Embodiment 1. The obtained lithium Ion batteries have a partially recessed structure, as shown in Figure 4.

Specific implementation mode 5

The difference from Embodiment 1 is that the punched holes on the packaging film are obtained by punching after packaging, and other processes are the same as Embodiment 1.

It should be noted that, in addition to the shapes listed in the above specific embodiments, the shape of the punching hole can also be any closed or non-closed figure such as a circle, rectangle, triangle, trapezoid, etc.

Compared with the prior art, the special-shaped lithium-ion battery of the utility model solves the problem that the traditional lithium-ion battery cannot meet the power supply requirements of special-shaped electronic products, especially electronic products where the battery is placed with protrusions or parts that need to be hollowed out. The adoption of the lithium ion battery of the utility model solves the problem that multiple batteries need to be connected in parallel due to irregular shapes of electronic products (such as local protrusions). On the premise of satisfying the capacity of electronic products, the utility model greatly reduces the production quantity of lithium ion batteries and improves the production efficiency of lithium ion batteries. In addition, the lithium-ion battery of the present utility model has a recessed design or a hollow design locally, and the lithium-ion battery can also play a role of fixing the battery by matching the corresponding recessed or hollowed out part with the shape of the electronic product. Placing the battery inside the electronic product to shift or shake can protect the edges and corners of the battery from being damaged, and reduce the chance of internal short circuit of the battery due to the extrusion of the corners.

It should be noted that, according to the disclosure and elaboration of the above specification, those skilled in the art to which the present utility model belongs can also change and modify the above embodiment. Therefore, the utility model is not limited to the specific implementation manners disclosed and described above, and some equivalent modifications and changes to the utility model should also be within the protection scope of the claims of the utility model. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present utility model.

Claims (5)

1. A special-shaped lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet, a diaphragm and an encapsulation film, is characterized in that: the positive electrode sheet is provided with a positive electrode sheet punching hole, the negative electrode sheet is provided with a negative electrode sheet punching hole, and the diaphragm is provided with a positive electrode sheet punching hole. Diaphragm punching, after the positive electrode sheet, diaphragm and negative electrode sheet are wound or laminated to form a cell, the centers of the positive electrode sheet punching hole, the negative electrode sheet punching hole and the diaphragm punching hole all fall on the same straight line to form a connection the gap. 2. The special-shaped lithium-ion battery according to claim 1, characterized in that: the punching holes for the positive electrode sheet, the negative electrode sheet and the diaphragm are respectively set in the central area or the edge area of the battery cell. 3. The special-shaped lithium-ion battery according to claim 1, characterized in that: the punched holes of the positive electrode sheet, the punched hole of the negative electrode sheet and the punched diaphragm are in the shape of a circle, a square, a triangle or a trapezoid. 4. The special-shaped lithium-ion battery according to claim 1, characterized in that: the packaging film is provided with a packaging film punching hole, and the center of the packaging film punching hole and the cell punching hole fall on the same straight line. 5. The special-shaped lithium-ion battery according to claim 4, characterized in that: the diameter or side length of the positive plate punching, the negative plate punching, the diaphragm punching and the packaging film punching is greater than or equal to 0.1 μm.

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