CN213782070U - Naked electric core of range upon range of formula - Google Patents

Abstract

The utility model provides a naked electric core of range upon range of formula, including negative pole (3), diaphragm (1) and positive pole (2), range upon range of negative pole (3), diaphragm (1) and positive pole (2) form electric core, diaphragm (1) is the multilayer, distributes between positive pole (2) and negative pole (3), the coating has rubber coating solution on the electric core edge, and insulating layer (5) cover in naked electric core edge. The utility model discloses cladding method simple process once only accomplishes the cladding, and the cladding area is little, and manufacturing cost obviously reduces, and it is little to change current technology production line, and maneuverability is strong.

Description

Naked electric core of range upon range of formula

Technical Field

The utility model relates to a lithium cell technical field especially relates to a naked electric core of range upon range of formula.

Background

Since the introduction of commercialization of nonaqueous electrolyte lithium ion batteries by sony corporation in the 90 s, various types of electronic portable devices have been widely used due to their high energy density, long cycle life, and the like. In recent years, with further expansion of the application field of lithium batteries, large-capacity lithium batteries have also entered the fields of electric vehicles, electric tools, energy storage, and the like. The battery has large size and large capacity, the use safety problem of the battery is gradually highlighted, and the requirement on the performance is improved.

The current lithium ion battery mainly comprises two processes of winding and lamination. Compared with the two processes, the stacked battery cell has the advantages of high volume utilization rate, high energy density and difficult deformation. The multiple pole pieces are connected in parallel, so that the internal resistance is relatively low, and the rate discharge performance is excellent. Laminated cells also have inherent drawbacks. For example, in the production process of the laminated lithium ion battery, the pole pieces are formed by slicing and stacking layer by layer, relative dislocation is easy to occur in the subsequent transfer process, the positive pole and the negative pole are misaligned, the diaphragm cannot cover the positive pole and the negative pole, and the pole pieces are contacted with each other, so that short circuit is caused. Moreover, the laminated lithium ion battery pole piece is formed by slicing, and all the peripheries of the laminated lithium ion battery pole piece are provided with cutting surfaces, so that burrs are inevitably generated. These burrs easily pierce the separator and tend to cause poor cell shorting during the manufacturing process. After unidentified tiny burrs enter the battery, the electric field at the edge burrs is larger than that at other places, and the current density is large. Particularly, burrs at the positive electrode are large in current density of a corresponding negative electrode area in the lithium ion battery lithium desorption process, so that the negative electrode is easy to precipitate lithium, and once dendrites penetrate through the diaphragm, the battery is short-circuited or even is burnt.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to overcome the defect that prior art exists, the utility model provides a naked electric core of range upon range of formula and preparation method thereof simplifies cladding method technology, reduction in production cost.

In order to solve the technical problem, the utility model discloses a technical scheme is: the utility model provides a naked electric core of range upon range of formula, includes negative pole, diaphragm and positive pole, and range upon range of negative pole, diaphragm and positive pole form electric core, the diaphragm distributes between positive pole and negative pole, the coating has rubber coating solution on the electric core edge, and the insulating layer covers on naked electric core edge.

Furthermore, an insulating layer is coated on the edge of one side, which does not contain a tab, of the battery cell, the edges of the positive electrode and the negative electrode and the diaphragm are communicated through the insulating layer, and the insulating layer realizes conformal coating on the edges of the positive electrode and the negative electrode and the edge of the diaphragm; the covered depth of the edge of the positive electrode is not more than 10mm, and preferably 1-5 mm.

Furthermore, the four edge corners of the battery core are coated with insulating layers, and the edges of the positive electrode and the negative electrode are communicated with the diaphragm through the insulating layers; the insulating layer realizes conformal coating on the edges of the positive electrode and the negative electrode and the edge of the diaphragm. The covered area of the edge of the insulating layer is 4-100 mm²。

Further, the coating manner of the coating solution includes any one of spraying, brushing, spot coating and dipping.

Compared with the prior art, the beneficial effects of the utility model include:

1) the cyano group and the carbonyl group with stronger electron withdrawing in the alpha-cyanoacrylate molecule can react with trace moisture in the air to initiate the polymerization of the alpha-cyanoacrylate monomer, and can be quickly cured at room temperature, so that the conformal coating and bonding of the positive and negative electrode edges and the diaphragm are realized;

2) the bonding layer not only wraps up the burr at the edge of the naked electric core, thereby reducing the short circuit risk brought by the burr. Meanwhile, the positive and negative pole pieces and the diaphragm are bonded together to fix the pole pieces, so that the phenomenon of movement or dislocation of the positive and negative pole pieces in the subsequent manufacturing process is avoided;

3) the coating method has the advantages of simple process, one-time coating completion, small coating area, obvious reduction of production cost, small change to the existing process production line and strong operability.

Drawings

The disclosure of the present invention is explained with reference to the drawings. It is to be understood that the drawings are designed solely for the purposes of illustration and not as a definition of the limits of the invention. In the drawings, like reference numerals are used to refer to like parts. Wherein:

fig. 1 is a partial cross-sectional view of a stacked cell.

Fig. 2 schematically shows a top view of a stacked bare cell according to a first embodiment of the invention.

Fig. 3 schematically shows a top view of a stacked bare cell according to a second embodiment of the invention.

Fig. 4 schematically shows a top view of a stacked bare cell according to a third embodiment of the invention.

Reference numbers in the figures: 1-diaphragm, 2-anode, 3-cathode, 4-tab and 5-insulating layer.

Detailed Description

It is easily understood that, according to the technical solution of the present invention, a plurality of alternative structural modes and implementation modes can be proposed by those skilled in the art without changing the spirit of the present invention. Therefore, the following detailed description and the accompanying drawings are merely illustrative of the technical solutions of the present invention, and should not be considered as limiting or restricting the technical solutions of the present invention in their entirety or in any other way.

According to an embodiment of the present invention, shown in fig. 1, a method for preparing a stacked bare cell includes the following steps:

s1, the negative electrode 3, the diaphragm 1 and the positive electrode 2 are alternately stacked to form a battery cell, and the diaphragm 1 is located between the positive electrode 2 and the negative electrode 3.

And S2, preparing a gluing solution, coating the gluing solution on the battery cell prepared in the S1, drying and curing to obtain the laminated battery cell with the edge coated with the insulating layer 5.

The glue coating solution comprises the following components in percentage by mass: 1-45% of a cross-linking agent, 0.5-10% of a tackifier, 2-10% of a modifier and 35-96.5% of a solvent;

the cross-linking agent is alpha-cyanoacrylate with a simple structure formula of CH₂C (cn) -COO-R. R is an aliphatic chain, such as methyl, ethyl, propyl, butyl, and the like. Specifically, the crosslinking agent includes one or a combination of more of methyl α -cyanoacrylate, ethyl α -cyanoacrylate, propyl α -cyanoacrylate, butyl α -cyanoacrylate, and the like.

The tackifier comprises polyacrylate resin such as polymethacrylate PMA, polymethyl methacrylate PMMA, methyl acrylate-acrylonitrile copolymer, cyanoacrylate maleic acid dipropargyl ester copolymer, etc.

The modifier comprises polyvinylidene fluoride-hexafluoropropylene PVDF-HFP, polyethers such as polyethylene oxide PEO, polyacrylonitrile PAN, polypropylene oxide PPO and one or more of polyvinylpyrrolidone PVP.

The solvent with the boiling point lower than 100 ℃ specifically comprises one or a mixture of more of acetone, butanone, dimethyl carbonate, ethylene glycol dimethyl ether and tetrahydrofuran.

The glue coating liquid can rapidly infiltrate the edges of the positive electrode and the negative electrode of the bare cell, cover the surfaces of the positive electrode and the negative electrode, and infiltrate the diaphragm 1. Because the solvent with a lower boiling point is adopted, cyano and carbonyl with stronger electron withdrawing in alpha-cyanoacrylate molecules can react with trace moisture in the air along with the rapid volatilization of the solvent to initiate the polymerization of the alpha-cyanoacrylate monomers, and can be rapidly cured at room temperature, so that the conformal coating and bonding of the anode and cathode edges and the diaphragm 1 are realized. This bond line not only wraps up the burr at naked electric core edge to reduce the short circuit risk that the burr brought. Meanwhile, the positive and negative pole pieces and the diaphragm 1 are bonded together to fix the pole pieces, so that the phenomenon of movement or dislocation of the positive and negative pole pieces in the subsequent manufacturing process is avoided. Compared with the prior art, the modified material provided by the invention can be used as a viscosity regulator, can regulate the flexibility of the cured glue, has a certain adhesive force, can be used as an auxiliary adhesive, and can improve the adhesive force of a coating on the diaphragm 1. Therefore, in the whole life cycle of the battery, the relative positions of the positive and negative pole pieces are fixed all the time, so that the safety performance and the reliability of the battery are further improved.

According to a first coating mode of the invention, shown in combination with fig. 2, a stacked bare cell comprises a negative electrode 3, a diaphragm 1 and a positive electrode 2, the stacked negative electrode 3, the diaphragm 1 and the positive electrode 2 form the bare cell, the diaphragm 1 comprises multiple layers and is distributed between the positive electrode 2 and the negative electrode 3, tabs 4 are arranged on the side edges of the positive electrode 2 and the negative electrode 3, the four edge corners of the bare cell are coated with a gluing solution, the coating mode comprises any one of spraying, brushing, spot coating and dip coating, dip coating is preferred, and the immersion time is 0.5-30 s, preferably 1-10 s. The edges of the anode and the cathode are communicated with the diaphragm 1 by the insulating layer 5, and the coverage area of the edges of the insulating layer 5 is 4-100 mm²Preferably 9 to 50mm²。

According to a second coating mode of the invention, shown in combination with fig. 3, a stacked bare cell comprises a negative electrode 3, a diaphragm 1 and a positive electrode 2, the stacked negative electrode 3, the diaphragm 1 and the positive electrode 2 form the bare cell, the diaphragm 1 comprises multiple layers and is distributed between the positive electrode 2 and the negative electrode 3, the side edges of the positive electrode 2 and the negative electrode 3 are provided with tabs 4, the bare cell does not contain any one of the edges of the two sides of the tab 4, the coating mode comprises any one of spraying, brushing, point coating and dip coating, dip coating is preferred, and the immersion time is 0.5-30 s, preferably 1-10 s. The insulating layer 5 is communicated with the edges of the anode and the cathode and the diaphragm 1, so that the insulating layer 5 can conformally coat the edges of the anode and the cathode and the edge of the diaphragm 1, and the covered depth of the edge of the anode 2 is not more than 10 mm.

According to a third coating mode of the invention, shown in combination with fig. 4, a stacked bare cell comprises a negative electrode 3, a diaphragm 1 and a positive electrode 2, the stacked negative electrode 3, the diaphragm 1 and the positive electrode 2 form the bare cell, the diaphragm 1 comprises multiple layers and is distributed between the positive electrode 2 and the negative electrode 3, a tab 4 is arranged on the same side edge of the positive electrode 2 and the negative electrode 3, a coating solution is coated on the side edge and the bottom edge of the bare cell, the coating mode comprises any one of spraying, brushing, spot coating and dip coating, dip coating is preferred, and the immersion time is 0.5-30 s, preferably 1-10 s. The insulating layer 5 connects the edges of the positive and negative electrodes and the separator 1, and the area covered by the edges and depth of the insulating layer 5 are the same as those in the above embodiment.

The coating method includes, but is not limited to, the method disclosed in the above embodiment, and only needs to ensure that the depth of the side edge of the laminated bare cell, which does not contain the tab, is not more than 10mm in dip-coating the coating solution. Compared with other embodiments, the coating method for coating the coating solution on the four edge corners of the battery cell saves the coating solution and is lower in cost.

And (3) placing the bare cell prepared in the step into a battery shell, and injecting an electrolyte into the battery shell to obtain the lithium ion battery, wherein the battery shell can adopt an aluminum shell or an aluminum-plastic film, and the electrolyte is various non-aqueous electrolytes commonly used by the lithium ion battery, so that the battery shell and the non-aqueous electrolytes are not required to be limited. The separator 1 disposed between the cell positive electrode 2 and the cell negative electrode 3 only needs to be able to insulate and isolate the cell positive electrode 2 and the cell negative electrode 3. The materials commonly used in the prior art can be prepared without special limitation.

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All raw materials in the examples are commercially available.

Example 1

1. And (5) preparing a laminated bare cell. The positive plate containing lithium iron phosphate, the negative plate containing artificial graphite and the polypropylene porous diaphragm with the thickness of 20um are formed by alternately laminating through a laminating machine, and the pole lugs are assembled to form bare cells at two ends respectively.

2. And (5) preparing a gluing solution. Mixing alpha-ethyl cyanoacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene and acetone in a weight ratio of 5: 1: 2: 92, mixing and stirring the mixture into a uniform glue solution.

3. And (5) coating the naked electric core. Respectively soaking four corners of the bare cell obtained in the step 1 in a glue solution, and controlling the area of the edge of the positive electrode, which is immersed in the glue solution, to be 32mm²And taking out the film after 2 seconds, standing and drying the film to form the film.

4. And (4) placing the naked battery core in the step (4) into an aluminum-plastic film shell with a good pit, packaging, drying, injecting electrolyte, aging, standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 2

1. Preparing a laminated bare cell: the positive plate containing lithium iron phosphate, the negative plate containing artificial graphite and the single-layer polypropylene porous diaphragm with the thickness of 16 mu m are formed by alternately laminating through a laminating machine, and the pole lugs are assembled to form bare cells at two ends respectively.

2. Preparation of a gluing solution: mixing alpha-methyl cyanoacrylate, polymethacrylate and polyvinylidene fluoride-hexafluoropropylene acetone according to a weight ratio of 1: 0.5: 5: 93.5, mixing and stirring to obtain a uniform glue solution.

3. Coating of the naked electric core: and (3) respectively soaking the two side edges of the bare cell in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 2mm, taking out the bare cell after 1 second, standing and drying the bare cell to form a film.

4. And (4) placing the bare cell obtained in the step (3) into a well-punched aluminum-plastic film shell, packaging, drying, injecting electrolyte, aging, standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 3

1. And (5) preparing a laminated bare cell. Contain lithium iron phosphate's positive plate, contain artificial graphite's negative pole piece and thickness 16 um's polyethylene diaphragm, form through the crisscross range upon range of lamination machine, assemble out the naked electric core of utmost point ear in same one side.

2. And (5) preparing a gluing solution. Mixing alpha-methyl cyanoacrylate, polymethacrylate, polyvinylpyrrolidone PVP: acetone, according to a weight ratio of 45: 5: 8: 42, mixing and stirring the mixture into a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking two side edges and the bottom edge of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 2mm, taking out the bare cell after 5 seconds, standing and drying the bare cell to form a film, as shown in figure 4.

4. And (3) placing the bare cell in the step (3) into a well-punched aluminum-plastic film, packaging, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 4

1. And (5) preparing a laminated bare cell. The positive plate that contains lithium iron phosphate, the polypropylene PP diaphragm of the three-layer coextrusion that contains artificial graphite's negative pole piece and thickness 14um, form through the crisscross range upon range of lamination machine, assemble out the naked electric core of utmost point ear at both ends.

2. And (5) preparing a gluing solution. Mixing alpha-ethyl cyanoacrylate, polymethacrylate, polyvinylidene fluoride-hexafluoropropylene and acetone according to a weight ratio of 5: 10: 10: and 75, stirring to obtain a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking the two side edges of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 3mm, taking out the bare cell after 4 seconds, standing and drying the bare cell to form a film.

4. And (3) placing the bare cell in the step (3) into an aluminum shell, performing laser welding sealing, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 5

1. And (5) preparing a laminated bare cell. The positive plate that contains lithium iron phosphate, the PP diaphragm that contains artificial graphite's negative pole piece and thickness 14 um's surface coating aluminium oxide forms through the crisscross range upon range of lamination machine, assembles out the naked electric core of utmost point ear at the homonymy head.

2. And (5) preparing a gluing solution. Mixing alpha-cyanoethyl acrylate, polymethyl methacrylate, polyethylene oxide and acetone according to a weight ratio of 15: 1: 5: 79, stirring to obtain a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking the two side edges and the bottom edge of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 1mm, taking out the bare cell after 2 seconds, standing, drying and forming a film.

4. And (3) placing the bare cell in the step (3) into an aluminum shell, performing laser welding sealing, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 6

1. And (5) preparing a laminated bare cell. The positive plate containing lithium iron phosphate, the negative plate containing artificial graphite and the polypropylene PP diaphragm co-extruded by three layers with the thickness of 16um are formed by alternately laminating through a laminating machine, and the naked electric core with the lug on the same side is assembled.

2. And (5) preparing a gluing solution. Mixing alpha-ethyl cyanoacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene and acetone according to a weight ratio of 3: 1: 6: and 90, stirring to obtain a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking the two side edges of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 4mm, taking out the bare cell after 10 seconds, standing and drying the bare cell to form a film.

4. And (3) placing the bare cell in the step (3) into an aluminum shell, performing laser welding sealing, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 7

1. And (5) preparing a laminated bare cell. The positive plate containing lithium iron phosphate, the negative plate containing artificial graphite and the polyethylene PE diaphragm with the thickness of 16 mu m coated with aluminum oxide are formed by alternately laminating through a laminating machine, and the bare cell with the lug at the same side is assembled.

2. And (5) preparing a gluing solution. Mixing alpha-butyl cyanoacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene and dimethyl carbonate according to a weight ratio of 2: 1: 5: 93, stirring to obtain a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking the two side edges and the bottom edge of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 5mm, taking out the bare cell after 15 seconds, standing, drying and forming a film.

4. And (3) placing the bare cell in the step (3) into an aluminum shell, performing laser welding sealing, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

Example 8

1. And (5) preparing a laminated bare cell. The lithium nickel cobalt manganese oxygen-containing positive plate is formed by alternately laminating a negative electrode containing artificial graphite and a polyethylene porous diaphragm with the thickness of 12 mu m and the surface coated with ceramic through a laminating machine, and a bare cell with lugs at two ends is assembled.

2. And (5) preparing a gluing solution. Mixing alpha-ethyl cyanoacrylate, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene: butanone according to the weight ratio of 10: 2: 3: 85, mixing and stirring to obtain a uniform glue solution.

3. And (5) coating the naked electric core. And (3) respectively soaking the two side edges of the bare cell obtained in the step (1) in a glue solution, controlling the depth of the edge of the positive electrode immersed in the glue solution to be 6mm, taking out the bare cell after 20 seconds, standing and drying the bare cell to form a film.

4. And (4) placing the bare cell in the step (4) into a well-punched aluminum-plastic film, packaging, drying, injecting electrolyte, aging and standing, and performing formation charging to obtain the lithium ion battery of the embodiment.

The technical scope of the present invention is not limited to the above description, and those skilled in the art can make various changes and modifications to the above-described embodiments without departing from the technical spirit of the present invention, and such changes and modifications should fall within the protective scope of the present invention.

Claims (4)

1. The utility model provides a naked electric core of range upon range of formula, its characterized in that includes negative pole (3), diaphragm (1) and anodal (2), and range upon range of negative pole (3), diaphragm (1) and anodal (2) form electric core, diaphragm (1) are the multilayer, distribute in between anodal (2) and negative pole (3), the coating has the rubber coating solution on the electric core edge, and insulating layer (5) cover in naked electric core edge.

2. The laminated bare cell according to claim 1, wherein the edge of one side of the cell, which does not include the tab (4), is coated with an insulating layer (5), the edges of the positive electrode (2) and the negative electrode (3) and the separator (1) are communicated through the insulating layer (5), and the insulating layer (5) realizes conformal coating on the edges of the positive electrode (3) and the negative electrode (3) and the edge of the separator (1); the depth of the edge of the positive electrode (2) covered is not more than 10 mm.

3. The stacked bare cell according to claim 1, wherein the four corners of the cell are coated with insulating layers (5), and the edges of the positive and negative electrodes (3) and the separator (1) are communicated with each other through the insulating layers (5); the covered area of the edge of the insulating layer (5) is 4-100 mm²。

4. The stacked bare cell according to claim 1, wherein the coating solution is applied by any one of spraying, brushing, spotting and dipping.

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