CN110048168B

CN110048168B - Cold pressing process of mixed solid-liquid electrolyte lithium storage battery

Info

Publication number: CN110048168B
Application number: CN201910319836.0A
Authority: CN
Inventors: 许晓雄; 董剑; 张永龙; 蒋阳慧
Original assignee: Zhejiang Funlithium New Energy Tech Co Ltd
Current assignee: Zhejiang Funlithium New Energy Tech Co Ltd
Priority date: 2019-04-19
Filing date: 2019-04-19
Publication date: 2022-04-05
Anticipated expiration: 2039-04-19
Also published as: CN110048168A

Abstract

The invention discloses a cold pressing process of a mixed solid-liquid electrolyte lithium storage battery, which relates to the field of solid batteries and adopts the technical scheme that the cold pressing process comprises the following steps: clamping the battery cell by using a cold pressing clamp; step two: circulating saponification liquid to the interior of the cold pressing clamp; step three: the cell is pressurized in stages. The method has the advantages that the saponification liquid is utilized to cool in the cold pressing process, and the pressure is applied in stages, so that the gas in the battery in the package in the formation process can be discharged into the air bag, the quality of the battery core can be improved, and the rapid formation of the battery core can be realized.

Description

Cold pressing process of mixed solid-liquid electrolyte lithium storage battery

Technical Field

The invention relates to the field of solid batteries, in particular to a cold pressing process of a mixed solid-liquid electrolyte lithium storage battery.

Background

With the development of energy sources in China, lithium batteries play more and more important roles, but the comprehensive performance of the lithium batteries is still to be improved. The best cold pressing process is found by researching the cold pressing process after the high-temperature pressurization formation of the lithium battery, so that the production cost is saved, and the comprehensive quality of the lithium battery is improved.

The cold pressing process for high-temperature pressurization of the lithium battery mainly has three functions: firstly, the comprehensive electrical property quality of the lithium battery is improved. Particularly, the rapid cold pressing can enable the contact between the anode and cathode materials in the battery cell and the diaphragm or the solid electrolyte to be tighter, so that gas is prevented from entering the space between the anode and cathode materials and the diaphragm or the solid electrolyte under the action of thermal diffusion, and the electrical property of the battery cell is reduced due to poor contact between the anode and cathode materials and the diaphragm or the solid electrolyte; secondly, the battery core can become smoother through the cold pressing process, so that the performance of the lithium battery is improved; thirdly, can be with the quick next step process that carries on of electric core to practice thrift manufacturing cost, promote the efficiency of whole production.

The formation of the existing lithium battery generally comprises hot pressing and cold pressing, but only the hot pressing process is regionally refined, and the cold pressing process is not mentioned. For example, the formation method of the invention patent with the application number of 201710950337.2 and the grant publication number of CN 107579302A and the name of 'a soft package power lithium ion battery cell rapid formation method' comprises hot pressing, but only innovations are made on the hot pressing, and no cold pressing is involved. The hot pressing comprises the following specific steps:

firstly, heating a battery cell by using a heating plate heat supply;

secondly, driving a pressing plate by using a servo motor to pressurize the battery cell;

step-type charging is carried out on the battery cell;

and fourthly, charging each battery cell to a high charge state.

In the traditional cold pressing process, the whole process only adopts one-time maximum pressure for pressing, and the gas in the battery package can not be discharged in time at the moment of extrusion, so that the battery package can be acted, and the battery package is easy to deform or even become thin or broken.

Disclosure of Invention

The invention aims to provide a cold pressing process of a mixed solid-liquid electrolyte lithium storage battery, which can effectively exhaust gas generated in the formation process of the lithium battery and can not easily cause deformation of battery packages.

The technical purpose of the invention is realized by the following technical scheme:

a formation process of a mixed solid-liquid electrolyte lithium storage battery mainly comprises the following steps:

the method comprises the following steps: clamping the battery cell by using a cold pressing clamp;

step two: circulating saponification liquid or deionized water to the interior of the cold pressing clamp;

step three: the cell is pressurized in stages.

Here, the saponification liquid is utilized or the saponification liquid is cooled during the cold pressing process, and the pressure is applied in stages, so that the gas generated in the formation process of the lithium battery can be discharged, the quality of the lithium battery can be improved, and the lithium battery can be rapidly formed.

And select the deionized water as the coolant, mainly the deionized water can prevent that the dirt of aquatic from blockking circulating pipe to also help improving cold pressing efficiency.

Preferably, the first stage is performed under 0.03-0.06MPa for 0-15 min, the second stage is performed under 0.07-0.2 MPa for 0-45 min, and the third stage is performed under 0.25-0.4 MPa for 0-45 min.

By adopting the technical scheme, the pressure of 0.03-0.06MPa is selected to be applied in the first stage, so that the gas between the diaphragm and the anode and cathode materials is slowly exhausted after the formation is finished. And the pressure of the second step of pressing is slightly increased, so that the electrolyte can be prevented from being discharged by excessive pressure while the normal gas is ensured. The third step is to discharge the gas in the cell main body as much as possible on the basis of the first and second steps due to the large pressure, so that the gas in the cell can be completely discharged.

Preferably, the composition comprises, by mass, 7-11 parts of petroleum sodium sulfonate, 1-5 parts of nitrite, 6-7 parts of triethanolamine, 8-12 parts of oleic acid and 1-3 parts of 1, 2-dodecenylsuccinic acid.

Preferably, the nitrite is one or more of sodium nitrite, potassium nitrite or ammonium nitrite.

Through adopting above-mentioned technical scheme, here, through the synergistic action of petroleum sodium sulfonate and nitrite, can improve the cooling effect of saponification liquid effectively.

Preferably, the cold pressing fixture comprises laminate plates, a cavity is formed in each laminate plate, and a liquid inlet pipe and a liquid outlet pipe which are communicated with the cavity are formed in each laminate plate. Therefore, the saponified liquid can be circulated to flow through the cavity of the laminate, and the cooling effect of the clamp on the battery can be improved. A bearing film is arranged between the two layers of plates.

Through adopting above-mentioned technical scheme, like this before anchor clamps are exerted pressure, the staff can put electric core on the supporting membrane earlier to slide to the intermediate position of two plywoods under the effect of electric core self gravity, be favorable to guaranteeing like this that the plywood is stable to be held electric core with holding, thereby improved the quality of colding pressing of electric core.

Preferably, the two laminates are provided with detachable protruding strips close to the sealing opening of the cell package.

By adopting the technical scheme, the clamp is pressed in stages, so that large pressure does not exist between the two convex strips at the early stage, and gas in the battery cell can be discharged from the seal of the battery cell. Later, along with the pressure grow between the sand grip, and when the gas in the electric core was also arranged completely, then at this moment, then can reduce during external air enters into the electric core, and cause the influence in the electric core.

Preferably, the laminate is provided with a sliding groove, and the raised line is provided with a sliding block matched with the sliding groove.

Through adopting above-mentioned technical scheme, can select the sand grip according to the electric core of different specifications like this, when improve equipment practical efficiency, also be favorable to improving the efficiency of colding pressing to different electric cores.

In conclusion, the invention has the following beneficial effects:

1. by applying pressure in stages, gas in the battery can be fully exhausted, and the shape deformation of the battery can be avoided;

2. the nitrite is added into the saponified solution, so that the sodium petroleum sulfonate and the nitrite can act synergistically, the cooling effect of the saponified solution is effectively improved, and the deionized water is adopted to ensure that the service life of the equipment is longer on the premise of keeping the cold pressing effect unchanged;

3. the clamp is provided with a convex strip at the sealing position of the package of the battery cell, so that the external air can be effectively prevented from entering the battery cell while the gas in the battery cell is exhausted;

4. moreover, the convex strips are matched with the laminate plates through the sliding grooves and the sliding blocks, so that the convex strips can be conveniently disassembled and replaced, and the cold pressing operation is conveniently suitable for the electric cores of different specifications.

Drawings

Fig. 1 is a schematic structural view of a cold pressing jig according to the first embodiment.

In the figure, 1, a laminate; 11. a liquid inlet pipe; 12. a liquid outlet pipe; 2. a support film; 3. a convex strip; 31. a slider; 4. a chute.

Detailed Description

The first embodiment is as follows:

a cold pressing fixture, as shown in figure 1, comprises a laminate 1, wherein the laminate 1 is provided with a driving mechanism, the driving mechanism can drive two laminates 1 to press, the specific driving mechanism can be selected according to actual conditions, for example, an oil cylinder can be respectively arranged on the opposite sides of the two laminates 1.

In addition, a supporting film 2 is arranged between the two laminates 1, and the upper edges of the supporting films 2 are respectively fixed with the positions close to the upper edges of the laminates 1, so that the supporting films 2 can be used for bearing the battery cell. Meanwhile, the two-layer plate 1 is internally provided with a cavity, and the back side of the two-layer plate 1 is provided with a liquid inlet pipe 11 and a liquid outlet pipe 12 which are communicated with the cavity. The liquid inlet pipe (11) is arranged above and the liquid outlet pipe (12) is arranged below.

Furthermore, a convex strip 3 is installed on the opposite surface of the two laminates 1, and the convex strip 3 is positioned above the upper edge of the supporting film 2. The laminate is provided with the sliding grooves 4, the protruding strips 3 are provided with the sliding blocks 31 matched with the sliding grooves 4, and therefore the protruding strips 3 and the laminate 2 can be effectively disassembled and assembled through the matching of the sliding grooves 4 and the sliding blocks 31, and cold pressing operation on different specifications of battery cores is facilitated.

Example II,

A formation process of a mixed solid-liquid electrolyte lithium storage battery comprises the following steps:

the method comprises the following steps: charging the battery cell by adopting a constant current mode with the temperature of 45 ℃, the pressure of 0.3Mpa and the current of 0.2C and a cutoff voltage of 3.75V;

step two: placing the battery core processed in the first step on a supporting film of the cold-pressing fixture in the first embodiment, and then slightly clamping the battery core by the cold-pressing fixture;

step three: introducing circulating saponification liquid into a cavity of the cold pressing clamp;

step four: and then, the cold pressing fixture applies pressure to the battery cell in stages, wherein the pressure applied in the first stage is 0.06MPa, the time is 7min, the pressure applied in the second stage is 0.07MPa, the time is 15min, and the pressure applied in the third stage is 0.325MPa, and the time is 45 min.

Step five: after the pressure is applied, the battery core is taken out;

wherein, the saponification liquid is formed by mixing 7kg of petroleum sodium sulfonate, 1kg of sodium nitrite, 6kg of triethanolamine, 8kg of oleic acid and 1kg of 1, 2-dodecenylsuccinic acid.

Comparative example one:

the difference from the first embodiment is that in the fourth step, the cold pressing fixture applies pressure to the battery cell to a one-time pressure of 0.4Mpa, and the duration is 67 min.

Example III,

step two: placing the battery core processed in the step one on a supporting film of the cold pressing fixture in the embodiment one, and then slightly clamping the battery core by the cold pressing fixture;

step three: circulating deionized water is introduced into the cavity of the cold pressing fixture;

step four: then, the cold pressing fixture applies pressure to the battery cell in stages, wherein the pressure applied in the first stage is 0.03MPa and the time is 5min, the pressure applied in the second stage is 0.07MPa and the time is 15min, and the pressure applied in the third stage is 0.25MPa and the time is 15 min;

step five: and after the pressure is applied, taking out the battery core.

Comparative example II,

The difference from the third embodiment is that ordinary water is selected for cooling.

Example four,

step four: then, the cold pressing fixture applies pressure to the battery cell in stages, wherein the pressure applied in the first stage is 0.06MPa for 15min, the pressure applied in the second stage is 0.2 MPa for 45 min, and the pressure applied in the third stage is 0.4MPa for 45 min;

step five: and after the pressure is applied, taking out the battery core.

Wherein, the saponified liquid is prepared by mixing 11Kg of petroleum sodium sulfonate, 5Kg of potassium nitrite, 7Kg of triethanolamine, 12Kg of oleic acid and 3Kg of 1, 2-dodecenylsuccinic acid.

Example V,

step two: placing the battery core processed in the step one on a support film of the cold pressing fixture in the embodiment one, and then slightly clamping the battery core by the cold pressing fixture;

step four: then, the cold pressing fixture applies pressure to the battery cell in stages, wherein the pressure applied in the first stage is 0.045MPa, the time is 10min, the pressure applied in the second stage is 0.135MPa, the time is 30min, and the pressure applied in the third stage is 0.325MPa, and the time is 30 min;

step five: and after the pressure is applied, taking out the battery core.

Wherein, the saponification liquid is prepared by mixing 9Kg of petroleum sodium sulfonate, 3Kg of nitrite, 6.5Kg of triethanolamine, 10Kg of oleic acid and 2Kg of 1, 2-dodecenyl succinic acid, and the nitrite is prepared by mixing sodium nitrite, potassium nitrite and ammonium nitrite in a mass ratio of 1:1: 1.

Example six,

step five: and after the pressure is applied, taking out the battery core.

The cell is tested according to the following test methods:

1. the capacitance testing method comprises the following steps:

2. the internal resistance testing method comprises the following steps:

3. the cycle number test method comprises the following steps:

4. and observing whether the cell external package has abnormal deformation or damage.

Table one shows the experimental results of examples one to six and comparative examples one to three:

TABLE-Experimental results of various properties of the cell

Test items	Example two	EXAMPLE III	Example four	EXAMPLE five	EXAMPLE six	Comparative example 1	Comparative example No. two
								capacitance/Ah	29.9	28.5	29.9	30.1	29.0	26.3	27.1
Internal resistance/m omega	0.41	0.45	0.42	0.40	0.47	0.56	0.55
								Number of cycles	493	482	508	510	489	386	397
Appearance of the product	No abnormal sample	No abnormal sample	No abnormal sample	No abnormal sample	No abnormal sample	The package showed obvious cracking	Small package with bubble

As can be seen from comparison between the second to sixth examples in table one and the second and third examples and the first and second comparative examples, respectively, the cold pressing process of the present application improves the capacity performance and the cycle number of the battery, reduces the internal resistance of the battery, and is not easy to cause variation of the external package of the battery core. Therefore, the battery formed by the method is suitable for more fields and has a long service life.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims

1. A cold pressing method of a mixed solid-liquid electrolyte lithium storage battery comprises the following steps:

step two: circulating saponification liquid to the interior of the cold pressing clamp;

step three: pressurizing the battery core by stages;

wherein, saponification liquid: 7-11 parts of petroleum sodium sulfonate, 1-5 parts of nitrite, 6-7 parts of triethanolamine, 8-12 parts of oleic acid and 1-3 parts of 1, 2-dodecenylsuccinic acid by mass;

in the third step, the first stage is applied with pressure of 0.03-0.06MPa for 0-15 min, the second stage is applied with pressure of 0.07-0.2 MPa for 0-45 min, and the third stage is applied with pressure of 0.25-0.4 MPa for 0-45 min.

2. The cold pressing method of a mixed solid-liquid electrolyte lithium battery as claimed in claim 1, wherein: the nitrite is one or more of sodium nitrite, potassium nitrite or ammonium nitrite.

3. The cold pressing method of a mixed solid-liquid electrolyte lithium battery as claimed in claim 1, wherein: the cold pressing fixture comprises two layer plates (1), a cavity is formed in each layer plate, and a liquid inlet pipe (11) and a liquid outlet pipe (12) which are communicated with the cavities are formed in each layer plate (1).

4. A cold pressing method of a mixed solid-liquid electrolyte lithium secondary battery according to claim 3, characterized in that: a supporting film (2) is arranged between the two layers of plates (1).

5. A cold pressing method of a mixed solid-liquid electrolyte lithium secondary battery according to claim 3, characterized in that: the sealing part of the two laminates (1) close to the battery core is provided with a detachable convex strip (3).

6. The cold pressing method of a mixed solid-liquid electrolyte lithium battery as claimed in claim 5, wherein: a sliding groove (4) is formed in the laminated plate (1), and a sliding block (31) matched with the sliding groove (4) is arranged on the protruding strip (3).