阅读说明：本技术 纽扣电池卷芯及其制备方法及使用该卷芯的纽扣电池 (Button battery roll core, preparation method thereof and button battery using same ) 是由 王华平 李朋 唐松林 向磊 于 2020-12-23 设计创作，主要内容包括：本申请涉及锂离子电池技术领域,具体公开了一种纽扣电池卷芯及其制备方法及使用该卷芯的纽扣电池。本申请的纽扣电池卷芯的制备方法,包括如下步骤：1)将正极浆料涂覆在正极集流体的两侧表面,烘干,在正极集流体的两侧形成正极材料层,得到正极片；将负极浆料涂覆在负极集流体的两侧表面,烘干,在负极集流体的两侧形成负极材料层,得到负极片；2)向正极片、负极片中的至少一个的表面喷涂极片柔化处理剂,然后进行卷绕,制得纽扣电池卷芯；极片柔化处理剂由包括如下重量份数的原料混合制成：柔化剂60-75份、附着剂10-15份、分散剂15-25份。本申请的纽扣电池卷芯在后续充放电过程中不易掉粉,电池的循环寿命长。(The application relates to the technical field of lithium ion batteries, and particularly discloses a button battery roll core, a preparation method of the button battery roll core and a button battery using the roll core. The preparation method of the button battery winding core comprises the following steps: 1) coating the positive electrode slurry on the surfaces of the two sides of a positive electrode current collector, drying, and forming positive electrode material layers on the two sides of the positive electrode current collector to obtain a positive electrode plate; coating the negative electrode slurry on the surfaces of the two sides of a negative electrode current collector, drying, and forming negative electrode material layers on the two sides of the negative electrode current collector to obtain a negative electrode piece; 2) spraying a pole piece softening treatment agent on the surface of at least one of the positive pole piece and the negative pole piece, and then winding to obtain a button cell winding core; the pole piece softening treatment agent is prepared by mixing the following raw materials in parts by weight: 60-75 parts of softening agent, 10-15 parts of adhesive and 15-25 parts of dispersing agent. The button cell roll core is difficult for falling powder in the follow-up charge and discharge process, and the cycle life of the cell is long.)

1. A preparation method of a button battery winding core is characterized by comprising the following steps:

1) coating the positive electrode slurry on the surfaces of the two sides of a positive electrode current collector, drying, and forming positive electrode material layers on the two sides of the positive electrode current collector to obtain a positive electrode plate; the positive electrode slurry comprises a positive electrode active substance, wherein the positive electrode active substance is at least one of lithium cobaltate, a ternary material and lithium manganate;

coating the negative electrode slurry on the surfaces of the two sides of a negative electrode current collector, drying, and forming negative electrode material layers on the two sides of the negative electrode current collector to obtain a negative electrode piece;

2) spraying a pole piece softening treatment agent on the surface of at least one of the positive pole piece and the negative pole piece, and then winding the positive pole piece, the negative pole piece and the diaphragm to obtain a button cell winding core; the pole piece softening treatment agent is prepared by mixing the following raw materials in parts by weight: 60-75 parts of a softening agent, 10-15 parts of an adhesive and 15-25 parts of a dispersing agent, wherein the softening agent is at least one of diethylenetriamine, tetraethylenepentamine, chloropropane, carbon tetrachloride and butylene oxide; the adhesive is at least one of hexanol, butanediol, pentanediol and glycerol; the dispersant is at least one of ethanol and methanol.

2. The method for preparing the button cell roll core according to claim 1, wherein the softening agent in the step 2) is composed of diethylenetriamine, chloropropane and butylene oxide in a mass ratio of 40-50:10-15: 5-10.

3. The method for preparing the button cell winding core according to claim 1, wherein the adhesive in the step 2) is composed of n-hexanol, pentanediol and glycerol in a mass ratio of 3-4:5-8: 2-3.

4. The preparation method of the button cell winding core according to claim 1, wherein the dispersing agent in the step 2) consists of ethanol and methanol in a mass ratio of 10-15: 5-10.

5. The method for preparing the button cell winding core according to any one of claims 1-4, wherein the pole piece softening agent in the step 2) is sprayed on one side surface of the corresponding positive pole piece or negative pole piece, and the side of the positive pole piece or negative pole piece sprayed with the pole piece softening agent faces the center of the winding core when winding is carried out.

6. The preparation method of the button cell roll core according to claim 5, wherein the positive electrode slurry is coated on the two side surfaces of the positive electrode current collector in the step 1), dried and then rolled; and coating the negative electrode slurry on two side surfaces of the negative electrode current collector, drying and rolling.

7. The preparation method of the button cell roll core according to claim 1, wherein the spraying amount of the pole piece softening agent on the corresponding surface of the positive pole piece or the negative pole piece in the step 2) is 0.1-0.2g/cm²。

8. The method for preparing the button cell winding core according to claim 7, wherein the thickness of the positive electrode material layer on each side of the positive electrode sheet is 150-220 μm; the thickness of the negative electrode material layer on each side of the negative electrode sheet is 120-180 μm.

9. A button cell winding core prepared by the preparation method of claim 1.

10. A button cell using the jellyroll of claim 9.

Technical Field

The application relates to the technical field of lithium ion batteries, in particular to a button battery roll core, a preparation method of the button battery roll core and a button battery using the roll core.

Background

Consumer electronic devices are generally powered by a built-in rechargeable battery due to their portability requirements. The lithium ion battery has obvious advantages, and is widely applied to a plurality of consumer electronic devices, and the consumer electronic devices also have larger market share of the lithium ion battery. The type and size of the lithium ion battery built in the electronic equipment can change along with the type and size of the electronic equipment, for example, a cylindrical lithium ion battery is mostly adopted in a notebook computer with a larger volume, and a soft package battery is mostly adopted in a notebook computer, a tablet computer and a mobile phone with a smaller volume.

In recent years, the miniaturization trend of many consumer electronic devices is obvious, such as bluetooth headsets, and the size of the devices is smaller and smaller, so that the size of lithium ion batteries built in the devices is also smaller and smaller, and small cylindrical batteries and square soft package batteries cannot be assembled in small bluetooth headsets. In order to meet the miniaturization of the Bluetooth headset, a plurality of manufacturers develop special-shaped small soft package batteries, such as strip-shaped soft package batteries, which are embedded in a headset handle. But this kind of laminate polymer battery's extranal packing rigidity is relatively poor, and is inconvenient fixed, to more miniature beans formula bluetooth headset, can't realize fine adaptation moreover. In contrast, some battery manufacturers have developed button-type lithium ion batteries that are easy to install and secure. But button lithium ion battery's capacity is lower, and most button lithium ion battery inside adopts two disc formula electrodes moreover, and the electrode material layer on positive plate and the negative pole piece is all than thicker, and charge-discharge performance has received the influence, can lead to bluetooth headset's duration to descend, influences user experience, and this problem can be solved better to coiling formula button battery.

Chinese patent application publication No. CN102804473A discloses a button cell comprising two metal housing halves separated from each other by an electrically insulating seal and forming a housing having a planar bottom area and a planar top area parallel thereto; an electrode separator assembly comprising at least one positive electrode and at least one negative electrode inside a housing, the assembly being provided in the form of a preferably helical winding, the end side of the assembly facing in the direction of a planar bottom region and a planar top region; and metal conductors electrically connecting the at least one positive electrode and the at least one negative electrode to one of the housing halves, respectively, wherein at least one of the conductors is connected to each housing half by welding. The preparation method of the button cell comprises the following steps: (a) providing first and second metal housing halves, (b) placing an electrode separator assembly comprising a positive electrode and a negative electrode in one of the housing halves, the metal conductor being bonded to at least one of the electrodes, (c) assembling the two housing halves, optionally providing a separate step for sealing the housing, and (d) welding at least one of the conductors to the inside of one of the metal housing halves, wherein step (d) is performed after step (c).

In view of the above-mentioned related technologies, the inventor believes that when the button cell is manufactured, the electrode separator assembly adopts a spiral winding form, and since the winding core of the button cell is small, the electrode material on the pole piece is easily extruded during winding, so that powder falling is caused in the subsequent use process, and the cycle life of the cell is reduced.

Disclosure of Invention

In order to improve the cycle performance of the button battery, the application provides a button battery winding core, a preparation method of the button battery winding core and the button battery using the winding core.

In a first aspect, the application provides a method for manufacturing a button cell winding core, which adopts the following technical scheme:

a preparation method of a button battery winding core comprises the following steps:

1) coating the positive electrode slurry on the surfaces of the two sides of a positive electrode current collector, drying, and forming positive electrode material layers on the two sides of the positive electrode current collector to obtain a positive electrode plate; the positive electrode slurry comprises a positive electrode active substance, wherein the positive electrode active substance is at least one of lithium cobaltate, a ternary material and lithium manganate;

coating the negative electrode slurry on the surfaces of the two sides of a negative electrode current collector, drying, and forming negative electrode material layers on the two sides of the negative electrode current collector to obtain a negative electrode piece;

2) spraying a pole piece softening treatment agent on the surface of at least one of the positive pole piece and the negative pole piece, and then winding the positive pole piece, the negative pole piece and the diaphragm to obtain a button cell winding core; the pole piece softening treatment agent is prepared by mixing the following raw materials in parts by weight: 60-75 parts of a softening agent, 10-15 parts of an adhesive and 15-25 parts of a dispersing agent, wherein the softening agent is at least one of diethylenetriamine, tetraethylenepentamine, chloropropane, carbon tetrachloride and butylene oxide; the adhesive is at least one of hexanol, butanediol, pentanediol and glycerol; the dispersant is at least one of ethanol and methanol.

By adopting the technical scheme, the pole piece softening treatment agent is sprayed on the surface of the anode material layer of the prepared anode piece or the surface of the cathode material layer of the prepared cathode piece, the pole piece softening treatment agent contains the softening agent, the softening agent can act with active substances or binders in the anode material layer or the cathode material layer, the toughness of the anode material layer or the cathode material layer is improved, the anode material layer or the cathode material layer on the pole piece is difficult to break when the pole piece is bent, the appearance of surface cracks of the pole piece is reduced, and further, the phenomenon of powder falling on the surface of the pole piece is reduced in the using process of the prepared battery, the charging and discharging circulation stability of the battery is improved, and the circulation life of the battery is prolonged. The adhesive in the pole piece softening agent is uniformly dispersed in the pole piece softening agent under the action of the dispersing agent, so that the softening agent can be attached to the surface of material particles on the pole piece, the retention time of the softening agent is prolonged, the pole piece is kept in a relatively wet state before winding is completed, and the winding effect is improved.

Preferably, the softening agent in the step 2) is composed of diethylenetriamine, chloropropane and butylene oxide in a mass ratio of 40-50:10-15: 5-10.

By adopting the technical scheme, the softening agent is compounded by selecting chloropropane, epoxybutane and diethylenetriamine, and the chloropropane can improve the permeability of the flexible treating agent, so that the flexible treating agent can enter the electrode material layer on the pole piece more easily. The epoxy butane can improve the effect of the flexible treating agent and the binder in the pole piece of the lithium battery, and further improves the softening effect. The amount of the diethylenetriamine is relatively large, and the diethylenetriamine can be ensured to fully play a softening role.

Preferably, the adhesive in the step 2) is composed of n-hexanol, pentanediol and glycerol in a mass ratio of 3-4:5-8: 2-3.

By adopting the technical scheme, the adhesive is compounded by the hexanol, the pentanediol and the glycerol, the combination of the flexible treating agent and the binder is enhanced by utilizing the hydroxyl in the molecule, and different carbon chain structures of various adhesives can be utilized to be better combined with the softening agent and the dispersing agent, so that the dispersion uniformity of the flexible treating agent is improved.

Preferably, the dispersing agent in the step 2) consists of ethanol and methanol in a mass ratio of 10-15: 5-10.

By adopting the technical scheme, the dispersing agent is compounded by ethanol and methanol, the amount of the ethanol is controlled to be large, the good compatibility between the ethanol and other components of the flexible treating agent can be fully utilized, the dispersing uniformity of the softening agent on the pole piece is improved, and the methanol has small molecules and good penetrating power and can drive the flexible treating agent to permeate into the electrode material layer on the pole piece.

Preferably, the pole piece softening agent in step 2) is sprayed on one side surface of the corresponding positive pole piece or negative pole piece, and when winding is performed, the side surface of the positive pole piece or negative pole piece sprayed with the pole piece softening agent faces the center of the winding core.

Through adopting above-mentioned technical scheme, through experimental discovery, coiling formula electric core is in the use, and the powder phenomenon that falls on the material layer of the inboard of rolling up the core is more serious, consequently, this application only sprays flexible finishing agent on the material layer of positive plate or negative plate towards the one side at rolling up core center, has both guaranteed to reduce the condition appearance that the pole piece surface falls powder by a wide margin, has also reduced the volume of remaining of flexible finishing agent in the pole piece after the follow-up stoving, has reduced the influence of composition in the flexible finishing agent to battery charge-discharge performance.

Preferably, the positive electrode slurry is coated on the surfaces of the two sides of the positive electrode current collector in the step 1), dried and rolled; and coating the negative electrode slurry on two side surfaces of the negative electrode current collector, drying and rolling.

By adopting the technical scheme, the positive electrode slurry or the negative electrode slurry can be rolled or not rolled after being coated. After rolling, the material layer on the surface of the pole piece is more compact, the multiplying power performance of the battery can be improved, and the battery is favorable for large-current charging and discharging.

Preferably, the spraying amount of the pole piece softening agent on the corresponding surface of the positive pole piece or the negative pole piece in the step 2) is 0.1-0.2g/cm²。

By adopting the technical scheme, the spraying amount of the pole piece softening agent on the surface of the pole piece is controlled to be smaller, so that the depth of the flexible treating agent entering the material layer on the surface of the pole piece is not too large, the residual amount of the flexible treating agent in the pole piece material layer is reduced, and the corrosion of the softening agent to the pole piece current collector is also reduced. And less spraying amount can soften the battery material on the surface of the material layer on the pole piece, and blocks the cracking and falling of the material in the deep part of the material layer, thereby ensuring the best powder falling prevention effect.

Preferably, the thickness of the positive electrode material layer on each side of the positive electrode sheet is 80-150 μm; the thickness of the negative electrode material layer on each side of the negative electrode sheet is 100-200 μm.

By adopting the technical scheme, the thickness of the positive plate and the thickness of the negative plate are not too thick, so that the occurrence of cracks on the surface of the wound pole piece can be further reduced, and meanwhile, the thickness of the pole piece is not too thin, so that the rate performance of the battery is favorably ensured.

The second aspect, this application provides a button cell rolls up core, adopts following technical scheme:

a button cell winding core prepared by the preparation method.

Through adopting above-mentioned technical scheme, the button cell roll core surface crackle that this application made is less, after making the lithium cell, is difficult to fall the powder, and the cycle life of battery improves greatly.

The third aspect, this application provides an use button cell of above-mentioned book core, adopts following technical scheme:

a button cell using the winding core is provided.

Through adopting above-mentioned technical scheme, the button cell of this application has adopted above-mentioned book core, and the button cell that will this book core assembly obtain is in the use, and circulation stability is high, and cycle life is long.

In summary, the present application has the following beneficial effects:

1. when the button cell roll core is prepared, the pole piece softening treatment agent is sprayed on the surface of the pole piece, the electrode material layer on the surface of the pole piece is softened, and then when the button cell roll core is wound, the electrode material layer on the surface of the pole piece is extruded, cracks are not prone to occurring on the surface and inside of the electrode material layer, stress concentration inside the electrode material layer is reduced, the button cell prepared by the roll core is not prone to powder falling in the follow-up charging and discharging process, and the cycle life is longer.

2. When the button cell roll core is prepared, the pole piece softening treatment agent is only sprayed on the electrode material layer on one side of the pole piece, and when the button cell roll core is wound, one side sprayed with the pole piece softening treatment agent faces the center of the roll core, so that the phenomenon of powder falling caused by extrusion easily occurring on the inner side of the cell is improved, meanwhile, the residue of the pole piece softening treatment agent in the electrode material layer of the pole piece is reduced, and the comprehensive performance of the cell is improved.

Drawings

Fig. 1 is a comparative graph of the cycling curves of the button cell of the present application.

Detailed Description

The present application will be described in further detail with reference to examples.

The button cell is any one of a CR2450 cell and a CR2477 cell, or a button cell with the diameter of 16mm and the thickness of 54mm or a button cell with the diameter of 20mm and the thickness of 54 mm.

When the pole piece softening agent is sprayed on the pole piece, the pole piece softening agent can be sprayed on both the positive pole piece and the negative pole piece, or can be sprayed on only the positive pole piece or the negative pole piece. When spraying the positive plate or the negative plate, the pole piece softening agent can be sprayed on the material layer surfaces on the two sides of the pole piece, or the pole piece softening agent can be sprayed on only one material layer surface on one side of the pole piece. After the pole piece softening agent is sprayed on the surface of the material layer on one side of the pole piece, the side sprayed with the pole piece softening agent faces the center of the winding core during winding.

Because the button cell of this application adopts coiling formula electricity core, and the width of the positive plate or the negative pole piece that button cell's coiling formula electricity core adopted is all smaller, leaves more burr when cutting easily, and is preferred, during positive plate or negative pole piece preparation, prepares the great pole piece strip of width earlier, after spraying pole piece softening agent to pole piece strip, cuts again, obtains corresponding positive plate or negative pole piece.

And drying after winding to obtain the button cell roll core. The drying temperature is 65-85 ℃, and the drying time is 12-24 h. After drying, volatile components in the pole piece softening agent in the roll core can fully escape, and the residual quantity on the pole piece is reduced.

The pentanediol adopted by the application is n-pentanediol, namely 1, 2-pentanediol; the butanediol is 1, 2-butanediol.

The positive electrode active substance is at least one of lithium cobaltate, a ternary material and lithium manganate, and preferably, the positive electrode active substance is the ternary material or is obtained by uniformly mixing the lithium cobaltate and the ternary material in a mass ratio of 1: 3. The ternary material is NCM ternary material or NCA ternary material, and the NCM ternary material is NCM111, NCM523, NCM622 or NCM 811.

The negative electrode slurry comprises a negative electrode active material, wherein the negative electrode active material is at least one of graphite, graphene, hard carbon and pyrolytic carbon. Preferably, the negative electrode active material is prepared by a method comprising the steps of: uniformly mixing a first solvent and a first matrix to obtain an inner-layer spinning solution; the first solvent is at least one of tetrahydrofuran, chloroform and toluene; the first matrix is at least one of polystyrene, styrene-methyl methacrylate copolymer and 2-methyl-2-butyl acrylate monomer; uniformly mixing a second solvent and a second matrix to obtain a middle-layer spinning solution; the second solvent is at least one of dimethylformamide, dimethyl sulfoxide and dimethyl sulfite; the second matrix is at least one of polyacrylonitrile and polyaniline; uniformly mixing a third solvent and a third matrix to obtain an outer-layer spinning solution; the third solvent is at least one of trimethylphenyl ammonium hydroxide and N-methylmorpholine-N-oxide; the third matrix is any one of cotton pulp and bamboo pulp; carrying out three-channel coaxial electrostatic spinning by using the obtained inner layer spinning solution, middle layer spinning solution and outer layer spinning solution to obtain composite fibers; the obtained composite fiber is subjected to heat preservation for 8-10h at the temperature of 700-900 ℃ under the protection of inert atmosphere to obtain the cathode active material. Further, the material obtained after the temperature is maintained at 900 ℃ for 8-10h at 700-. Preferably, sintering is carried out at 1100 ℃ for 2.5 h.

Preferably, when the negative electrode slurry is prepared, the mass ratio of the negative electrode active material, the negative electrode conductive agent, the negative electrode binder and the negative electrode dispersing agent is 95-98:0-2:2-5: 50-150. The negative electrode conductive agent is any one of SP, carbon nano tube and Ketjen black. The cathode binder is water-based binder or oily binder, the water-based binder is at least one of LA132, LA133 and sodium carboxymethyl cellulose CMC, and the oily binder is polyvinylidene fluoride PVDF or polytetrafluoroethylene PTFE. An oily binder is preferably used. The negative dispersing agent is water or N-methyl pyrrolidone. When the negative electrode binder is an aqueous binder, the negative electrode dispersant is water, and when the negative electrode binder is an oily binder, the negative electrode dispersant is N-methylpyrrolidone.

The mass ratio of the positive active substance to the positive conductive agent to the positive binder to the positive dispersant is 85-95:0-10:3-5: 50-70. The positive electrode conductive agent is any one of SP, graphene and Ketjen black. The positive binder is polyvinylidene fluoride (PVDF) or Polytetrafluoroethylene (PTFE). The positive dispersing agent is N-methyl pyrrolidone.

And uniformly mixing the positive active substance, the positive binder and the positive dispersing agent to prepare positive slurry, coating the positive slurry on the surfaces of the two sides of the positive current collector, drying, and forming positive material layers on the two sides of the positive current collector to obtain the positive plate. The temperature during drying is 80-100 ℃, and the drying time is 6-8 h. The vacuum degree during drying is 0.01-0.05 MPa.

And uniformly mixing the negative active material, the negative binder and the negative dispersing agent to prepare negative slurry, coating the negative slurry on the surfaces of the two sides of a negative current collector, drying, and forming negative material layers on the two sides of the negative current collector to obtain the negative plate. The temperature during drying is 70-80 ℃, and the drying time is 8-12 h. The vacuum degree during drying is 0.01-0.05 MPa.

The viscosity of the anode slurry is preferably 2500.

The spraying amount of the pole piece softening agent can be measured and determined by a weight comparison method, and then the spraying amount is controlled by controlling the flow of the high-pressure spray head.

When the positive plate or the negative plate is prepared, the tab can be welded on the corresponding positive current collector or negative current collector after the positive plate or the negative plate is prepared, and one end of the corresponding current collector can be left white to be used as the tab when coating is carried out.

After the button cell winding core is manufactured, 2 circles of diaphragm strips are wound outside the winding core and fixed by adhesive tapes. To fit square into the battery case.

The thickness of the positive electrode sheet is preferably 150 μm. The thickness of the negative electrode sheet is preferably 120 μm.

Example 1

The preparation method of the button battery winding core comprises the following steps:

1) uniformly mixing a positive electrode active substance, a positive electrode binder and a positive electrode dispersant according to a mass ratio of 95:5:50 to obtain positive electrode slurry, wherein the positive electrode active substance is a ternary material NCM523, the positive electrode binder is polyvinylidene fluoride (PVDF), and the positive electrode dispersant is N-methylpyrrolidone;

coating the positive electrode slurry on a positive electrode current collector aluminum foil with the thickness of 16 microns, then carrying out vacuum drying on the positive electrode current collector coated with the positive electrode slurry for 8 hours at the temperature of 90 ℃ and the vacuum degree of 0.01MPa, cooling to room temperature along with a furnace, then rolling, forming positive electrode material layers on two sides of the positive electrode current collector, and cutting to obtain the positive electrode plate.

Uniformly mixing a negative electrode active material, a negative electrode binder and a negative electrode dispersant according to a mass ratio of 95:5:150 to obtain negative electrode slurry; the negative electrode active substance is crystalline flake graphite, the negative electrode binder is obtained by mixing LA132 and carboxymethyl cellulose (CMC) according to the mass ratio of 3.5:1.5, and the negative electrode dispersing agent is deionized water;

coating the negative electrode slurry on a copper foil of a negative electrode current collector, wherein the thickness of the copper foil is 12 microns, then carrying out vacuum drying on the negative electrode current collector coated with the negative electrode slurry for 12 hours at 80 ℃ under the vacuum degree of 0.01MPa, cooling to room temperature along with a furnace, then rolling, forming negative electrode material layers on two sides of the negative electrode current collector, and then cutting to obtain a negative electrode sheet, wherein the width of the negative electrode sheet is slightly larger than that of the positive electrode sheet, the width of the negative electrode sheet is about 1.1 times of that of the positive electrode sheet, and the length of the negative electrode sheet is slightly larger than that of the positive electrode sheet and is about 1.05 times of that of.

2) Uniformly mixing diethylenetriamine, n-hexanol and ethanol according to the mass ratio of 60:15:25 to obtain a pole piece softening treatment agent;

spraying a pole piece softening agent to the surface of the positive electrode material layer on two sides of the positive electrode plate prepared in the step 1) through a high-pressure spray head, wherein the spraying amount of the pole piece softening agent is 0.1g/cm²；

Taking a celgard 2320 film (20 mu m thick, three-layer composite film) as a diaphragm, cutting the diaphragm into diaphragm strips, wherein the width of each diaphragm strip is 1.15 times of the width of the negative plate, and the length of each diaphragm strip is 2.3 times of the length of the negative plate; with the diaphragm strip along length direction fifty percent discount, then establish the negative pole piece clamp between the diaphragm strip, then stack the positive plate in the diaphragm's of negative pole piece one side the outside, align positive plate, negative pole piece, diaphragm along width direction's center, then convolute positive plate, negative pole piece, diaphragm cooperation, during convoluteing, the positive plate is in the inboard of negative pole piece (towards the one side at core center promptly, also when convoluteing towards the one side of rolling up the needle), makes button cell roll core.

The button cell that uses above-mentioned book core of this embodiment includes the casing, and the casing includes mutual seal complex positive plate shell and negative pole shell, is provided with above-mentioned button cell book core in the casing, and button cell rolls up the core and includes positive plate, negative pole piece and diaphragm, and the electricity is connected on the positive plate and is provided with anodal utmost point ear, and the electricity is connected on the negative pole piece and is provided with negative pole utmost point ear, and anodal utmost point ear is connected with the positive plate shell electricity, and negative pole utmost point ear is.

The preparation method of the button cell using the winding core in the embodiment comprises the following steps:

s1, welding a positive electrode lug on a positive electrode sheet of the button battery roll core, and welding a negative electrode lug on a negative electrode sheet, wherein the positive electrode lug is an aluminum belt or a nickel belt, and the negative electrode lug is a copper belt or a nickel belt;

s2, drying the button cell roll core welded with the positive electrode lug and the negative electrode lug at 85 ℃ for 18h, cooling to about 45 ℃, transferring into a glove box filled with argon, placing the roll core into a cavity inside a positive electrode shell of a button cell shell, dripping electrolyte, opening, vacuum standing for 30min, assembling the negative electrode shell and the positive electrode shell, and pressing and sealing to obtain the battery. The electrolyte adopts LiPF with the concentration of 1.0mol/L₆Solution, LiPF₆The solvent of the solution is formed by mixing dimethyl carbonate (DMC) and Ethylene Carbonate (EC) according to the volume ratio of 1: 1.

Example 2

The difference between the button cell winding core of the embodiment and the embodiment 1 is that in the step 2), diethylenetriamine is replaced by carbon tetrachloride. The others are the same as in example 1.

Example 3

The difference between the winding core of the button cell and the winding core of the button cell in the embodiment 1 is that diethylenetriamine is replaced by butylene oxide in the step 2). The others are the same as in example 1.

Example 4

The difference between the winding core of the button cell and the winding core of the button cell in the embodiment 1 is that diethylenetriamine is replaced by tetraethylenepentamine in the step 2). The others are the same as in example 1.

Example 5

The button cell winding core of the embodiment is different from that of the embodiment 1 in that n-hexanol is replaced by butanediol in the step 2). The others are the same as in example 1.

Example 6

The button cell winding core of the embodiment is different from that of the embodiment 1 in that ethanol is replaced by methanol in the step 2). The others are the same as in example 1.

Example 7

The button cell roll core of the embodiment is different from that of the embodiment 1 in that in the step 2), a softening agent, n-hexanol and ethanol are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the softening agent is obtained by mixing diethylenetriamine and chloropropane according to the mass ratio of 40: 20. The others are the same as in example 1.

Example 8

The button cell roll core of the embodiment is different from that of the embodiment 1 in that in the step 2), a softening agent, n-hexanol and ethanol are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the softening agent is prepared by mixing diethylenetriamine, chloropropane and butylene oxide according to the mass ratio of 40:15: 5. The others are the same as in example 1.

Example 9

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and ethanol are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the adhesive is prepared by mixing n-hexanol and pentanediol according to the mass ratio of 3: 7. The others are the same as in example 8.

Example 10

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and ethanol are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the adhesive is prepared by mixing n-hexanol, pentanediol and glycerol according to the mass ratio of 4:8: 3. The others are the same as in example 8.

Example 11

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and a dispersing agent are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the dispersing agent is obtained by mixing ethanol and methanol according to the mass ratio of 15: 10. The others are the same as in example 8.

Example 12

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and a dispersing agent are uniformly mixed according to a mass ratio of 60:15:25 to obtain a pole piece softening treatment agent; the softening agent is prepared by mixing diethylenetriamine, chloropropane and butylene oxide according to the mass ratio of 40:15: 5; the adhesive is prepared by mixing n-hexanol, pentanediol and glycerol according to the mass ratio of 3:5: 2; the dispersing agent is obtained by mixing ethanol and methanol according to the mass ratio of 15: 10. The others are the same as in example 8.

Example 13

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and a dispersing agent are uniformly mixed according to a mass ratio of 75:10:15 to obtain a pole piece softening treatment agent; the softening agent is prepared by mixing diethylenetriamine, chloropropane and butylene oxide according to the mass ratio of 50:15: 10; the adhesive is prepared by mixing n-hexanol, pentanediol and glycerol according to the mass ratio of 3:5: 2; the dispersing agent is obtained by mixing ethanol and methanol according to the mass ratio of 10: 5. The others are the same as in example 8.

Example 14

The button cell roll core of the embodiment is different from the button cell roll core of the embodiment 8 in that in the step 2), a softening agent, an adhesive and a dispersing agent are uniformly mixed according to a mass ratio of 68:13:19 to obtain a pole piece softening treatment agent; the softening agent is prepared by mixing diethylenetriamine, chloropropane and butylene oxide according to the mass ratio of 48:12: 8; the adhesive is prepared by mixing n-hexanol, pentanediol and glycerol according to the mass ratio of 4:7: 2; the dispersing agent is obtained by mixing ethanol and methanol according to the mass ratio of 12: 7. The others are the same as in example 8.

Example 15

The button cell winding core of the embodiment is different from the button cell winding core of the embodiment 14 in that the pole piece softening treatment agent is sprayed on the surfaces of the negative electrode material layers on the two sides of the negative electrode piece in the step 2), and the pole piece softening treatment agent is not sprayed on the surface of the positive electrode piece any more. The others are the same as in example 14.

Example 16

The button cell winding core of the present example is different from example 14 in that, in step 2), the pole piece softening agent is sprayed only on the surface of the positive electrode material on one side of the positive electrode sheet, and the side of the positive electrode sheet sprayed with the pole piece softening agent faces the center of the winding core (i.e., the side facing the winding needle during winding). The others are the same as in example 14.

Example 17

The button cell winding core of the embodiment is different from the button cell winding core of the embodiment 14 in that the pole piece softening agent is sprayed only on the surface of the negative electrode material on one side of the negative electrode sheet in the step 2), and the side of the negative electrode sheet sprayed with the pole piece softening agent faces the center of the winding core (i.e. the side facing the winding needle during winding). The others are the same as in example 14.

Example 18

The button cell roll core of the embodiment is different from that of the embodiment 17 in that the spraying amount of the pole piece softening agent is 0.2g/cm². The others are the same as in example 17.

Example 19

The button battery roll core of the embodiment is different from that of the embodiment 18 in that, in the step 1), the negative electrode current collector coated with the negative electrode slurry is subjected to vacuum drying, then is cooled to room temperature along with a furnace, is not rolled, and is directly cut to obtain the negative electrode piece. The others are the same as in example 18.

Example 20

The button battery roll core of the embodiment is different from that of the embodiment 19 in that, in the step 1), the negative electrode current collector coated with the negative electrode slurry is cooled to room temperature along with a furnace after being vacuum-dried, and is not rolled or cut, so that a negative electrode strip is obtained. And 2) spraying the pole piece softening agent on the negative electrode material layer on one side of the negative electrode strip in the step 2), and then cutting to obtain the negative pole piece. The others are the same as in example 19.

Example 21

The button cell winding core of the embodiment is different from the button cell winding core of the embodiment 20 in that the negative active material adopted in the step 1) is prepared by a method comprising the following steps:

a) preparation of the spinning dope

Preparing an inner layer spinning solution: taking 100g of first solvent tetrahydrofuran, stirring at 20 ℃, then adding 10g of polystyrene particles under the stirring condition, adding the polystyrene particles for multiple times, adding about 1g of polystyrene particles each time, adding about 1g of polystyrene particles again after the polystyrene particles are dissolved and disappear after adding each time until 12g of polystyrene is added, then adding 3g of 2-acrylic acid-2-methylpropyl ester homopolymer, and then stirring for 15min to prepare inner-layer spinning solution;

preparing a middle-layer spinning solution: taking 90g of second solvent N, N-Dimethylformamide (DMF), adding 10g of polyacrylonitrile powder, swelling for 24h, stirring at 75 ℃ at a rotating speed of 600r/min for 15h, and adding 1g of silicon monoxide (SiO) powder into the stirred mixed solution to prepare middle-layer spinning solution;

preparing an outer layer spinning solution: taking 30g of cotton pulp, crushing into powder, mixing with 200g of a third solvent N-methylmorpholine-N-oxide at 5 ℃ to obtain a premix, adding the premix into a double-screw extruder, extruding at 110 ℃ to obtain a cellulose solution, and standing the cellulose solution for 10 hours under the vacuum condition of the vacuum degree of 0.03MPa to obtain an outer-layer spinning solution.

b) Spinning

Taking the inner layer spinning solution, the middle layer spinning solution and the outer layer spinning solution to perform three-channel coaxial electrostatic spinning, and drying the fiber mass obtained by spinning for 5 hours at the temperature of 50 ℃ and under the vacuum condition of the vacuum degree of 0.02MPa to obtain composite fiber; during electrostatic spinning, the distance between the receiving plate and a spinning nozzle is 20cm, the voltage is 15kV, the flow rate of the spinning solution of the inner layer is 0.3mL/h, the flow rate of the spinning solution of the middle layer is 0.6mL/h, and the flow rate of the spinning solution of the outer layer is 0.4 mL/h; the inner diameter of an outer needle head of the three-channel coaxial needle head for three-channel coaxial spinning is 1.6mm, the inner diameter of a middle needle head is 0.8mm, and the inner diameter of an inner needle head is 0.4 mm.

c) Sintering

Putting the composite fiber obtained in the step 2) into a tubular furnace, continuously introducing argon into the tubular furnace, heating to 350 ℃ at a heating rate of 1 ℃/min, and preserving heat for 15 hours; and then heating to 700 ℃ at the heating rate of 3 ℃/min, then preserving the heat for 10 hours in the argon atmosphere, and then cooling to room temperature along with the furnace to obtain the composite cathode material.

Comparative example

Comparative example 1

The preparation method of the button cell winding core of the comparative example is different from that of the example 1 in that the pole piece softening treatment agent is not sprayed on the surface of the positive electrode material layer on the two sides of the positive electrode piece in the step 2). The rest is the same as in example 1.

Comparative example 2

The preparation method of the button cell winding core of the comparative example is different from that of the example 1 in that the pole piece softening agent in the step 2) is ethanol. The rest is the same as in example 1.

Comparative example 3

The preparation method of the button cell winding core of the comparative example is different from that of example 1 in that the pole piece softening agent in step 2) is n-hexanol. The rest is the same as in example 1.

Comparative example 4

The preparation method of the button cell winding core of the comparative example is different from that of the example 1 in that the pole piece softening agent in the step 2) is diethylenetriamine. The rest is the same as in example 1.

Performance test

The coin cells of examples 1 to 21 and comparative examples 1 to 4 were tested in the following manner:

(1) charge and discharge test

The discharge capacity was recorded as shown in Table 1, after charging at 0.1C and 4.2V cut-off voltage in the atmosphere of 25 ℃ and 55% humidity for 50min and discharging at 0.1C, 0.5C and 1C, respectively, and 3.0V cut-off voltage. The internal resistance of the cell was tested before charging and discharging as shown in table 1.

(2) Cycle testing

Under the conditions that the environment is 25 ℃ and the humidity is 55%, the battery is charged at 0.1C and then discharged at 0.1C, the charge-discharge cut-off voltage is respectively set to be 4.2V and 3.0V, and the cycle is repeated for 500 times, so that the recording capacity retention rate is shown in Table 1. The button cells of examples 1, 14, 15, 16, 17, and 19 were cycled up to 1000 times, and the cycling curves are shown in fig. 1.

TABLE 1 coin cell Performance testing in examples 1-21 and comparative examples 1-4

Comparing example 1 with comparative example 1 with table 1, it can be seen that the battery without spraying the electrode plate softening agent on the surface of the electrode plate has a smaller difference in the first discharge capacity than the battery with spraying the electrode plate softening agent on the surface of the electrode plate, and considering the capacity error caused by the influence of other processes during the preparation of the battery, the influence of spraying the electrode plate softening agent on the first discharge of the battery can be considered to be small. However, the cycle performance of the battery sprayed with the pole piece softening treatment agent on the surface of the pole piece is obviously improved, and the capacity retention rate is still higher after 500 cycles.

As can be seen from comparison of example 1 with comparative example 2 with table 1, when ethanol was used as the electrode sheet softening agent, the first discharge capacity of the battery was still not greatly affected, and there was only a slight difference in the first discharge capacity of the battery no matter how large the rate of discharge was, which may be related to the process consistency in manufacturing the battery. From the aspect of capacity retention rate after 500 cycles, ethanol is used as a pole piece softening treatment agent, and the cycle performance of the battery is hardly influenced.

Comparing example 1 with comparative example 3 with table 1, it can be seen that the use of n-hexanol as a pole piece softening agent has little effect on the first discharge capacity of the battery, but slightly improves the capacity retention rate after cycling of the battery.

Comparing example 1 with comparative example 4 with table 1, it can be seen that when diethylenetriamine is used as the electrode plate softening agent, the first discharge capacity of the battery is not greatly affected, but the cycle performance of the battery is greatly improved.

As can be seen from fig. 1 and examples 1, 14, 15, 16, 17, and 19, the button cell of the present application has good cycling performance and slow fading, and can maintain a capacity retention rate of 88% or more after 1000 cycles.

(3) Overcharge test

The lithium ion secondary battery of example 19 was placed at 25 ℃. + -. 3 ℃ and discharged to 3.0V at a current of 0.5C, and the battery was placed in an explosion-proof box. And connecting the thermocouple, connecting a power supply for charging (fixing a contact of the thermocouple at the central part of the surface of the battery cell), and charging to 4.6V at a constant current of 3C until the voltage of the battery cell reaches the maximum value. The test can be stopped if either of the following two conditions is satisfied:

a) the continuous charging time of the battery core reaches 7 h;

b) the cell temperature drops to 20% below the peak value.

The result of the overcharge test shows that the lithium ion storage battery has no phenomena of fire and explosion and has higher safety.

To sum up, the button battery that this application was made is high, and cycle performance stability is good, and cycle life is long, and the security is high.