CN2772034Y - Lithium ino cell - Google Patents

Abstract

The utility model relates to a lithium ion cell which comprises an anode, a cathode, a diaphragm and electrolytic solution which are commonly stored and contained in a cell shell and is sealed by a seal plate, wherein the anode, the cathode and the diaphragm form a cell pole piece body, and the bottom part of the cell pole piece body is coated with rubberized cloth, wherein the coated rubberized cloth is in a porous structure. The lithium ion cell causes the moisture removal speed of a pole piece of the cell to be high through the improvement of a bottom structure of the pole piece. After the electrolytic solution is filled in the cell, the infiltration speed of the electrolytic solution is high, and accordingly, the production period of the cell is shortened.

Description

A lithium ion battery

【Technical field】

The utility model relates to the technical field of lithium ion batteries, in particular to a pole core structure of the lithium ion battery.

【Background technique】

Lithium-ion battery is a small secondary battery widely used at present, which has the advantages of high specific energy, high working voltage, low self-discharge rate, long cycle life, and no pollution. However, the production cycle of lithium-ion batteries is relatively long. First, because lithium-ion batteries have strict requirements on the internal moisture of the battery, in order to remove the moisture of the internal pole pieces and separators of the battery, a long core baking time is required; After the non-aqueous electrolyte is poured, due to the high viscosity of the electrolyte, it takes a long time for the electrolyte to penetrate evenly into the positive and negative plates of the battery and all parts of the diaphragm. On the other hand, in the production process of conventional lithium-ion batteries, the bottom of the pole core is covered with adhesive tape. The purpose is to prevent the bottom of the pole core from being scratched by the metal shell during the process of installing the pole core into the metal shell. Short circuit; at the same time, the tape covered at the bottom of the pole core can effectively prevent the short circuit of the pole core caused by the shrinkage of the diaphragm under high temperature conditions. Therefore, the adhesive tape covered at the bottom of the pole core is an indispensable part of the lithium-ion battery. This brings about two problems: First, the adhesive tape coated on the bottom of the pole core prevents the water from being discharged through the bottom of the pole core during the process of removing moisture from the positive and negative plates and the diaphragm inside the pole core, and the water removal speed is slow. Longer pole core baking time; Second, the adhesive tape coated on the bottom of the pole core prevents the electrolyte from penetrating through the bottom of the pole core during the process of the non-aqueous electrolyte penetrating into the positive and negative electrodes and diaphragms inside the pole core. Inside the pole core, the penetration speed of the electrolyte is slow, and it takes a long time for the electrolyte to penetrate. This results in a long production cycle.

【Content of utility model】

The technical problem to be solved by the utility model is to provide a lithium-ion battery that shortens the production cycle of the battery by improving the bottom structure of the pole core so that the water removal speed of the battery pole core is fast and the battery electrolyte penetration speed is fast.

The technical problem to be solved by the utility model is achieved through the following technical solutions: a lithium-ion battery, including a positive electrode, a negative electrode, a diaphragm, and an electrolyte, are stored in a battery case together, sealed by a sealing plate, and the positive electrode, negative electrode, The diaphragm constitutes the battery pole core, and the bottom of the battery pole core is covered with adhesive tape, and the feature is that the covered adhesive tape has a porous structure.

The holes on the adhesive plaster are evenly arranged. Evenly distributed pores make the removal of water and the penetration of electrolyte more uniform and faster.

The hole area on the adhesive plaster is 0.5-5.0mm ² . If the area is too small, it will have little effect, and if the area is too large, it will also increase the difficulty of installing the battery pole core into the battery case, that is, it will be easily scratched by the battery case.

The beneficial effect of the utility model is: (1) the lithium-ion battery of the utility model, when the pole core is baked in making, the moisture of the positive and negative electrodes inside the pole core and the moisture of the diaphragm can pass through the adhesive tape coated at the bottom of the pole core. (2) After the non-aqueous electrolyte is poured into the lithium-ion battery of the utility model, the electrolyte can penetrate into the positive and negative poles of the pole core through the pores on the adhesive tape coated at the bottom of the pole core. Sheet and diaphragm, improve the penetration rate of electrolyte. Due to the favorable effects of the above two aspects, the pole core structure of the lithium-ion battery of the utility model can shorten the pole core baking time and electrolyte penetration time, thereby shortening the production cycle of the battery.

【Description of drawings】

FIG. 1 is a schematic diagram of the pole core structure of an embodiment of the lithium-ion battery of the present invention.

【Detailed ways】

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Please refer to Fig. 1 (Fig. 1 only shows the pole core body of the lithium-ion battery of the present invention), the lithium-ion battery of the present invention comprises positive pole 1, negative pole 2, separator 3, and electrolyte is accommodated in the battery casing jointly, by sealing plate Sealing, the positive electrode 1, the negative electrode 2, and the separator 3 constitute the battery pole core 4, and the bottom of the battery pole core is coated with adhesive tape 5, wherein the coated adhesive tape is a porous structure, as shown in Figure 1 Tape holes shown in 6. Wherein the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 can be wound to obtain a pole core body, and can also be laminated to form a pole core body; the adhesive tape can be a transparent or opaque insulating adhesive tape conventionally used in this field, such as OPP (Oriented Polymer Acrylic) adhesive tape; its thickness is not particularly limited, as conventional, it can be 0.01-0.1mm.

The porous structure on the adhesive plaster is a uniformly distributed or unevenly distributed porous structure; the shape of the holes can be regular shapes such as circles, ovals, triangles, squares, rhombuses or other irregular shapes; the size of the holes It is not particularly limited, but is preferably 0.5-5.0 mm ² . The hole structure is pre-set on the adhesive plaster before covering the bottom of the pole core. The required hole structure can be obtained on the adhesive tape by punching or other methods.

The adhesive plaster covering the bottom of the pole core can cover all or part of the bottom of the pole core.

The beneficial effects of the utility model are illustrated below through specific examples.

Example 1

Mix LiCoO ₂ (lithium cobalt oxide), acetylene black conductive agent, PVDF (polyvinylidene fluoride) binder, and NMP (nitromethylpyrrolidone) solvent, heat and stir to form a slurry, and coat it on both surfaces of aluminum foil After removing the NMP solvent by baking, it is cut into long sheet-shaped positive electrodes.

Mix natural graphite, PVDF binder, and NMP solvent, heat and stir to form a slurry, apply it on both surfaces of copper foil, remove the NMP solvent after baking, and cut into long sheet-shaped negative electrodes.

The PE/PP separator, positive electrode sheet and negative electrode sheet are stacked in the order of separator/positive electrode sheet/diaphragm/negative electrode sheet and then rolled into a pole core body. The bottom of the pole core is completely covered with OPP tape with a thickness of 0.040mm, and a row of circular holes with an area of ^2mm2 are uniformly arranged on the OPP tape corresponding to the middle position of the bottom of the pole core. The distance between the holes and the edges of the holes is 3mm. As shown in Figure 1.

Use a moisture testing instrument (765 KF coulometer) to measure the moisture content of the pole core. Then put the pole core in a vacuum oven at 70°C and bake for 6 hours. Measure the moisture content of the pole core again.

Example 2

Make pole core according to the same method as embodiment 1, then put pole core in aluminum square shell, inject by electrolytic salt LiPF ₆ (lithium hexafluorophosphate) and non-aqueous solvent EC (dimethyl carbonate), DEC (carbonic acid diethyl ether) Enyl ester) and DMC (dienyl carbonate) with a concentration of 1M non-aqueous electrolyte. After the battery was placed in an environment of 40°C for 8 hours, it was taken out to observe the penetration of the electrolyte into each part of the positive and negative electrodes and separator.

Comparative example 1

Except that no circular hole is set on the OPP adhesive plaster coated on the bottom of the pole core, the others are the same as in Embodiment 1.

Use a moisture testing instrument (765 KF coulometer) to measure the moisture content of the pole core. Then the pole core was baked in a vacuum oven at 70°C for 10 hours. Measure the moisture content of the pole core again.

Comparative example 2

A battery pole core was produced in the same manner as in Comparative Example 1.

Use a moisture testing instrument to measure the moisture content of the pole core. Then put the pole core in a vacuum oven at 70°C and bake for 6 hours. Measure the moisture content of the pole core again.

Comparative example 3

Make the pole core according to the same method as Comparative Example 1, then put the pole core into the aluminum square shell, inject the electrolyte salt LiPF ₆ (lithium hexafluorophosphate) and non-aqueous solvent EC (dimethyl carbonate), DEC (carbonic acid diethyl ether) Enyl ester) and DMC (dienyl carbonate) with a concentration of 1M non-aqueous electrolyte. After the battery was placed in an environment of 40°C for 12 hours, it was taken out to observe the penetration of the electrolyte into the positive and negative electrodes and separators.

Comparative example 4

Make the pole core according to the same method as Comparative Example 1, then put the pole core into the aluminum square shell, inject the electrolyte salt LiPF ₆ (lithium hexafluorophosphate) and non-aqueous solvent EC (dimethyl carbonate), DEC (carbonic acid diethyl ether) Enyl ester) and DMC (dienyl carbonate) with a concentration of 1M non-aqueous electrolyte. After the battery was placed in an environment of 40°C for 8 hours, it was taken out to observe the penetration of the electrolyte into each part of the positive and negative electrodes and separator.

The test and observation results are shown in the table below:

Table 1. Determination of batteries Core source Core Baking Time Pole core moisture content before baking Moisture content of pole core after baking Example 1 6 hours 900PPM 220PPM Comparative example 1 10 hours 900PPM 218PPM Comparative example 2 6 hours 900PPM 380PPM

It can be seen from the above table that the pole core moisture removal amount of the pole core body of Example 1 under a shorter baking time is basically the same as that of the pole core body of Comparative Example 1 under a longer baking time. It shows that the pole core structure of the lithium ion battery of Example 1 can improve the speed of pole core moisture removal.

Table 2. Determination of the battery Core source placement time electrolyte penetration Example 2 8 hours Evenly penetrate into all parts of the positive and negative electrode sheets and separators Comparative example 3 12 hours Evenly penetrate into all parts of the positive and negative electrode sheets and separators Comparative example 4 8 hours Penetrates into the local parts of the positive and negative electrodes and separators

It can be seen from the above table that the electrolyte penetration of the pole core of the lithium-ion battery of Example 2 at a shorter storage time is basically the same as that of the lithium-ion battery pole core of Comparative Example 2 at a longer storage time. Illustrate that the lithium-ion battery of Example 2 can increase the speed of electrolyte penetration.

Claims (3)

1. A lithium-ion battery, comprising a positive pole, a negative pole, a diaphragm, and an electrolyte that are jointly accommodated in a battery case, sealed by a sealing plate, the positive pole, the negative pole, and the diaphragm constitute a battery pole core, and the battery pole core The bottom covering adhesive plaster is characterized in that: the covering adhesive plaster has a porous structure. 2. The lithium-ion battery according to claim 1, wherein the holes on the adhesive tape are evenly arranged. 3. The lithium-ion battery according to claim 1 or 2, characterized in that: the hole area on the adhesive tape is 0.5-5.0 mm ² .

Images