CN113113608A

CN113113608A - Pole piece, preparation method of pole piece, battery core and battery

Info

Publication number: CN113113608A
Application number: CN202110395895.3A
Authority: CN
Inventors: 赵晓宁; 蔡挺威; 刘永飞; 梁世硕
Original assignee: Kunshan Bao Innovative Energy Technology Co Ltd
Current assignee: Kunshan Bao Innovative Energy Technology Co Ltd
Priority date: 2021-04-13
Filing date: 2021-04-13
Publication date: 2021-07-13

Abstract

The invention relates to a pole piece, a preparation method of the pole piece, a battery core and a battery, wherein the pole piece comprises: the method comprises the following steps: the current collector comprises a first surface and a second surface opposite to the first surface; the positive electrode layer is laminated on the first surface of the current collector; the negative electrode layer is laminated on the second surface of the current collector; wherein the positive electrode layer and the negative electrode layer are membranes comprising a fiberized polymer. The integration of positive negative pole of this pole piece can realize the interior cluster equipment of battery, when not increasing manufacturing cost, can improve electric core energy density effectively.

Description

Pole piece, preparation method of pole piece, battery core and battery

Technical Field

The invention relates to the technical field of batteries, in particular to a pole piece, a preparation method of the pole piece, a battery core and a battery.

Background

With the annual increase of the market share of new energy automobiles, the acceptance degree of the common public on the new energy automobiles is gradually improved, and the development of the new energy automobiles also enters a brand new stage; however, the new energy automobile has short driving distance and long charging time, and has a larger gap compared with the fuel oil automobile, and the new energy automobile is taken as an anxiety in most consumers. Therefore, how to increase the driving mileage of the new energy automobile and increase the energy density of the electric core for the automobile becomes an urgent problem.

According to the industry development and the technical current situation, the ways of improving the energy density of the battery cell are various, and the modes can be roughly divided into two layers of materials and the battery cell; in the aspect of materials, for example, high specific capacity negative electrode materials (silicon carbon negative electrodes, silicon negative electrodes and lithium metal negative electrodes), high specific capacity positive electrodes (high nickel and lithium-rich positive electrodes), high voltage positive electrodes (lithium cobaltate and lithium manganate) and the like are adopted, but the improvement in the aspect of materials is often difficult, and a major breakthrough is still not obtained at present; in the aspect of the battery core, the proportion of useless components (the part which does not provide capacity) in the battery core is mainly reduced, and the battery core comprises a thinner positive and negative current collector foil and a diaphragm; the anode and cathode formula is optimized, and the active substance ratio is improved. However, the above method has a limited effect of increasing the energy density and may result in a significant increase in production costs.

Disclosure of Invention

Therefore, a pole piece, a preparation method of the pole piece and a battery cell are needed to be provided. The integration of positive negative pole of this pole piece can realize the interior cluster equipment of battery, when not increasing manufacturing cost, can improve electric core energy density effectively.

A pole piece, comprising:

a current collector comprising a first face and a second face opposite the first face;

a positive electrode layer laminated on the first surface of the current collector;

a negative electrode layer laminated on the second surface of the current collector;

wherein the positive electrode layer and the negative electrode layer are membranes comprising a fiberized polymer.

In one embodiment, a first conductive layer is disposed between the current collector and the positive electrode layer, and a second conductive layer is disposed between the current collector and the negative electrode layer.

In one embodiment, the positive electrode layer comprises the following components in percentage by mass: 0.5-20% of fiberization polymer, 50-98% of positive active substance, 0.5-10% of conductive agent and 0-20% of polymer additive.

In one embodiment, the negative electrode layer comprises the following components in percentage by mass: 1-20% of a fiberization polymer, 60-98% of a negative electrode active material, 0.5-5% of a conductive agent and 0-15% of a polymer additive.

In one embodiment, the fiberizing polymer is fiberized polytetrafluoroethylene.

In one embodiment, the positive active material is selected from: one or more of ternary NMC positive electrode material, lithium cobaltate, lithium manganate and lithium iron phosphate.

In one embodiment, the negative active material is selected from: one or more of graphite, silicon oxygen and lithium titanate.

In one embodiment, the conductive agent is selected from: one or more of Super-P, carbon black, Ketjen black, carbon nanotubes, graphene, activated carbon, and carbon nanofibers.

In one embodiment, the polymeric additive is selected from: one or more of polyvinylidene fluoride, sodium carboxymethylcellulose, polystyrene, styrene-butadiene rubber and polyacrylic acid.

A preparation method of a pole piece comprises the following steps:

preparing a positive electrode membrane containing a fiberization polymer as a positive electrode layer;

preparing a negative electrode membrane containing a fiberized polymer as a negative electrode layer;

and laminating the positive electrode layer and the negative electrode layer on two opposite surfaces of a current collector to obtain the pole piece.

In one embodiment, the step of preparing the positive electrode layer includes the steps of:

mixing the raw materials for forming the positive electrode layer, processing in a non-fiberization mixing mode, and processing in a fiberization mixing mode to obtain a positive electrode mixed material;

processing the anode mixed material by adopting a high-speed airflow shearing method to obtain anode fiberization powder;

and carrying out hot pressing on the positive electrode fiberization powder to prepare a positive electrode membrane as a positive electrode layer.

In one embodiment, the step of preparing the negative electrode layer includes the steps of:

mixing the raw materials for forming the negative electrode layer, processing in a non-fiberizing mixing mode, and processing in a fiberizing mixing mode to obtain a negative electrode mixed material;

treating the negative electrode mixed material by adopting a high-speed airflow shearing method to obtain negative electrode fiberized powder;

and carrying out hot pressing on the negative electrode fiberization powder to prepare a negative electrode diaphragm serving as a negative electrode layer.

In one embodiment, the non-fiberizing mixing method is: and vibrating the mixed materials or mechanically stirring the mixed materials at a stirring speed of less than or equal to 3500 rpm.

In one embodiment, the fiberizing mixture is: ball milling mixing, extruder mixing or mechanical stirring with a stirring speed of more than 3500 rpm.

In one embodiment, in the step of performing fiberization treatment on the positive electrode mixture or the negative electrode mixture by using a high-speed airflow shearing method, the treatment parameters are as follows: the air flow speed is more than or equal to Mach 2.5, and the time is more than or equal to 5 min.

In one embodiment, the raw materials for forming the positive electrode layer include, by mass: 0.5-20% of fiberizable polymer, 50-90% of positive active substance, 0.5-10% of conductive agent and 0-10% of polymer additive.

In one embodiment, the raw materials for forming the negative electrode layer include, by mass: 1-8% of fiberizable polymer, 60-98% of negative active material, 0.5-5% of conductive agent and 0-5% of polymer additive.

In one embodiment, the compacted density of the positive electrode membrane is 2.0-4.0g/cc, and the thickness of the positive electrode membrane is 30-300 μm;

the compacted density of the negative electrode diaphragm is 1.0-2.5g/cc, and the thickness of the negative electrode diaphragm is 30-250 mu m.

A battery cell comprises a plurality of pole pieces connected in series, wherein the pole pieces are the pole pieces or the pole pieces prepared by the preparation method.

A battery comprises the battery core.

The invention has the following beneficial effects:

through with positive polar layer, the negative pole layer is range upon range of respectively in the relative two sides of mass flow body, form positive polar layer, mass flow body and negative pole layer integral structure, so be convenient for realize string in the electric core among the electric core assembling process, can show and promote electric core energy density, and through adopting the diaphragm that contains the fiberization polymer as positive polar layer and negative pole layer, can form the flexible film of self-supporting that has higher intensity, so suppress in the relative two sides of mass flow body through modes such as roll-in and can realize the preparation of positive negative polar integral structure, moreover, the operation is simple, can save cost, thereby realize when not increasing manufacturing cost, can improve electric core energy density effectively.

Drawings

FIG. 1 is a schematic view of a pole piece according to an embodiment of the present invention;

FIG. 2 is a schematic view of a diaphragm according to an embodiment of the present invention;

FIG. 3 is a diagram of the cycling performance of the pole pieces according to one embodiment of the present invention.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The weight of the related components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present invention as long as it is in accordance with the description of the embodiments of the present invention. Specifically, the weight described in the description of the embodiment of the present invention may be a unit of mass known in the chemical industry field, such as μ g, mg, g, and kg.

As shown in fig. 1, a first aspect of the present invention provides a pole piece 10, including: the current collector 100, the positive electrode layer 200, and the negative electrode layer 300, wherein the current collector 100 includes a first face and a second face opposite to the first face; the positive electrode layer 200 is laminated on the first surface of the current collector 100; the negative electrode layer 300 is laminated on the second surface of the current collector 100; the positive electrode layer 200, the current collector 100, and the negative electrode layer 300 form an integrated structure.

The technical personnel of the invention discover through research that: in the current market, the internal parallel connection mode is adopted inside the battery cells, which is also the reason that the voltage of the battery cells which are assembled at present is maintained at a lower level (not more than 4.5V). On the basis of the existing material system, in order to meet the application places of high energy density and high voltage of the battery cell, the internal series connection of the battery cell is an effective way, but the existing battery cell pole piece preparation process is all manufactured in a double-sided coating and drying mode, the same positive and negative electrode coatings are kept on the two sides of the same current collector (the positive electrode coating is coated on the two sides of a positive electrode aluminum foil, and the negative electrode coating is coated on the two sides of a negative electrode copper foil), and the internal series connection of the battery cell cannot be realized. However, if the positive and negative electrode coatings are integrated on the front and back sides of the same current collector in a certain manner, the series connection inside the battery cell can be realized, so that the output voltage of the battery cell can be effectively improved, and the purpose of applying the battery cell in a high-voltage place is achieved.

It should be noted that the term "two opposite surfaces" in the present invention means two surfaces opposite to each other, and the two opposite surfaces may be parallel to each other or not parallel to each other, which is only required to be not contradictory to the purpose of the present invention, and thus should be understood as being within the protection scope of the present invention.

In some embodiments, positive electrode layer 200 and negative electrode layer 300 are membranes comprising a fiberized polymer. The inventor of the present invention found in research that a self-supporting film (as shown in fig. 2) can be formed by adding a fiberized polymer to raw materials for forming a positive electrode and a negative electrode, and the prepared self-supporting films of the positive electrode and the negative electrode are pressed on two opposite surfaces of a current collector by rolling, so as to realize the preparation of the integrated structure of the positive electrode and the negative electrode, and the method has the advantages of simple operation and cost saving. And the diaphragm containing the fiberization polymer is adopted as the anode and the cathode, so that the strength of the anode and the cathode can be improved, and the requirement of modern production can be met.

In the present invention, the "fiberized polymer" refers to a fibrous polymer formed by fiberizing a polymer. "fiberizable polymer" means a polymer that can be fiberized by a particular process (e.g., mechanical agitation, high-velocity air shear, etc.), i.e., a "fiberizable polymer" that is obtained by a particular process, e.g., polytetrafluoroethylene is a "fiberizable polymer" that is fiberized by high-velocity air shear, etc., to obtain fiberized polytetrafluoroethylene. It is to be understood that the method for fiberizing a polymer in the present invention is not particularly limited, and conventional methods can be used, and the fiberizing method according to the present invention is preferably used. In addition, the type of the fiberizable polymer can be selected according to actual requirements, and the fiberizable polymer is preferably a fluorine-containing polymer with the fluorine element ratio of more than 50 percent; further, the fiberizable polymer is a fluoropolymer having a fluorine content of greater than 70%. The fluorine-containing fiberization polymer can improve the high temperature resistance of the pole piece to a certain extent, and has flame retardance, so that the stability and the safety of the pole piece can be effectively improved.

In some embodiments, the fiberizing polymer is fiberized Polytetrafluoroethylene (PTFE). The fluorine content of the polytetrafluoroethylene is up to 76%, and the polytetrafluoroethylene has high flame retardant property and high mechanical strength and can effectively improve the strength of the membrane.

In some embodiments, the positive electrode layer comprises: a fiberization polymer, a positive electrode active material, a conductive agent and a polymer additive; furthermore, in the positive electrode layer, the mass percentage of the fiberization polymer is 0.5-20%, the mass percentage of the positive electrode active substance is 50-98%, the mass percentage of the conductive agent is 0.5-10%, and the mass percentage of the polymer additive is 0-20%.

In some embodiments, the positive electrode layer comprises 0.5-20% by mass of the fiberization polymer; further, the mass percentage content of the fiberization polymer is 1-10%; further, the mass percentage of the fiberizing polymer is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14% or 16%.

In some embodiments, the positive electrode layer contains 50 to 98 mass percent of the positive electrode active material; further, the mass percentage content of the positive active substance is 80-98%; further, the positive electrode active material is contained in an amount of 60%, 70%, 75%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 95%, 96%, 97%, or 98% by mass.

In some embodiments, the positive active material is selected from: one or more of a ternary NMC positive electrode system, Lithium Cobaltate (LCO), Lithium Manganate (LMO) and lithium iron phosphate (LFP).

In some embodiments, the mass percentage of the conductive agent in the positive electrode layer is 0.5% -10%; further, the mass percentage content of the conductive agent is 1-5%; further, the content of the conductive agent is 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 6%, 7% or 8% by mass.

In some embodiments, the conductive agent is selected from one or more of Super-P, carbon black, ketjen black, Carbon Nanotubes (CNTs), graphene (rGO), activated carbon, and Carbon Nanofibers (CNFs).

In some embodiments, the mass percentage of the polymer additive in the positive electrode layer is 0.1-20%; further, the mass percentage content of the polymer additive is 0.1-8%; further, the polymer additive is present in an amount of 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 15% or 18% by mass.

The polymer additive is added into the positive electrode layer, so that the positive electrode layer and the fiberized polymer can act together, the strength of the positive electrode layer is effectively improved, and the subsequent integrated preparation is facilitated.

In some embodiments, the polymeric additive is selected from: one or more of polyvinylidene fluoride (PVDF), sodium carboxymethylcellulose (CMC), Polystyrene (PS), Styrene Butadiene Rubber (SBR), and polyacrylic acid (PAA).

In some embodiments, the thickness of the positive electrode layer is 30-300 μm; further, the thickness of the positive electrode layer is 40-150 μm; further, the thickness of the positive electrode layer is 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 160 μm, 180 μm, or 200 μm.

In some embodiments, the positive-electrode layer has a compacted density of 2.0 to 4.0 g/cc; further, the positive-electrode layer has a compacted density of 2.5 to 3.8 g/cc.

In some embodiments, the negative electrode layer comprises: a fiberization polymer, a negative electrode active material, a conductive agent, and a polymer additive; further, in the negative electrode layer, the mass percentage content of the fiberization polymer is 1-20%, the mass percentage content of the negative electrode active material is 60-98%, the mass percentage content of the conductive agent is 0.5-5%, and the mass percentage content of the polymer additive is 0-15%.

In some embodiments, the mass percent content of the fiberization polymer in the negative layer is 1-8%; further, the mass percentage content of the fiberization polymer is 1.5-4%; further, the mass percentage of the fiberizing polymer is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or 7.5%.

In some embodiments, the negative electrode layer contains the negative electrode active material in an amount of 60 to 98% by mass; further, the mass percentage content of the negative active material is 75-97%; further, the negative electrode active material is contained in an amount of 65%, 70%, 75%, 78%, 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, or 96% by mass.

In some embodiments, the negative active material is selected from: one or more of graphite (Gr), silicon (Si), silicon oxide (SiOx), and Lithium Titanate (LTO).

In some embodiments, the polymer additive is 0-15% by mass of the negative electrode layer; further, the mass percentage content of the polymer additive is 0-5%; further, the mass percentage content of the polymer additive is 0-3%; further, the polymer additive is present in an amount of 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 4%, 6%, 8%, 10%, 12%, or 14% by mass.

In some embodiments, the mass percentage of the conductive agent in the negative electrode layer is 0.5% -5%; further, the mass percentage content of the conductive agent is 1-4%; further, the content of the conductive agent is 0.8%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.5%, 4%, 4.5%, or 5% by mass.

It will be appreciated that the polymer additive in the positive electrode layer may be the same as or different from the polymer additive in the negative electrode layer. The conductive agent in the positive electrode layer may be the same as or different from the conductive agent in the negative electrode layer.

In some embodiments, the thickness of the negative electrode layer is 30-250 μm; further, the thickness of the negative electrode layer is 40-150 μm; still further, the thickness of the negative electrode layer is 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 160 μm, 180 μm, or 200 μm.

In some embodiments, the compacted density of the negative electrode layer is 1.0 to 2.5 g/cc; further, the compacted density of the negative-electrode layer is 1.3 to 2.0 g/cc.

In some embodiments, a first conductive layer is disposed between the current collector and the positive electrode layer, and a second conductive layer is disposed between the current collector and the negative electrode layer, wherein the materials of the first conductive layer and the second conductive layer may be the existing conductive materials, and are not particularly limited herein.

In some embodiments, the current collector is a carbon cloth, a carbon-based current collector (e.g., carbon fiber paper), a copper aluminum composite current collector, or a stainless steel current collector. In some embodiments, the current collector is a composite current collector with copper on the side close to the negative diaphragm and aluminum on the side close to the positive diaphragm. The composite current collector can be made of copper foil and aluminum foil through welding, rolling, electroplating and other methods.

The invention provides a preparation method of a pole piece, which comprises the following steps:

s101: preparing a positive electrode layer; the relevant technical features of the positive electrode layer are as described above, and are not described herein again.

In some embodiments, the positive electrode layer is prepared using a dry process. The dry method for preparing the positive electrode layer can effectively avoid the use of solvent, reduce the complexity of operation, save the cost and avoid the influence of solvent residue on the performance of the electrode plate.

In some embodiments, step S101 includes the steps of:

s1011: mixing the raw materials for forming the positive electrode layer, processing in a non-fiberization mixing mode, and processing in a fiberization mixing mode to obtain a positive electrode mixed material;

it is understood that "non-fiberizing compounding means" in the present invention refers to compounding means that do not enable fiberization of the fiberizable polymer; "fiberization blend" refers to a blend that is capable of fiberizing a fiberizable polymer to form a fiberized polymer.

The non-fiberization mixing mode is adopted for mixing, and the fiberizable polymer is not fiberized, so that the viscosity of the whole raw material system is low, the mixing uniformity of the raw materials can be effectively improved, and the phenomena of agglomeration and the like are avoided; then, a fiberization mixing mode is adopted, so that the fiberizable polymer is primarily fiberized, the effect of subsequent treatment can be improved, and the basic performance of the diaphragm is improved.

In some embodiments, the non-fiberizing mixing means is: mechanical stirring, ultrasonic dispersion, ball milling and mixing, extruder mixing, vibration mixing and defoaming mixing; further, the non-fiberizing mixing mode is as follows: vibrating, defoaming and mixing or mechanically stirring at a stirring speed of less than or equal to 3500 rpm; further, the non-fiberizing mixing means is vibratory mixing. The vibration mixing is a mixing mode which is carried out by a vibration mode, and the mixing mode has no shearing force, so that the increase of the viscosity of the initial mixing material caused by the fiberization of the fiberizable polymer can be effectively avoided.

In some embodiments, the mixing time of the non-fiberizing mixing means is less than 10 min. In some embodiments, the mixing time is 2-8min with non-fiberizing mixing; in some embodiments, the mixing time with non-fiberizing mixing is 3min, 4min, 5min, or 6 min. In some embodiments, a non-fiberizing mixing mode adopts a pulse type mixing mode; further, the pulse mixing mode is mixing for 0.5-3min, stopping for 0.5-1.5min, and repeating the above steps.

In some embodiments, the non-fiberizing mixing is vibratory agitation at a vibratory frequency of greater than 20KHz for a mixing time of 4-6 min.

In some embodiments, the non-fiberizing mixing is mechanical agitation at a speed of 500rpm to 3500rpm (preferably 2500rpm to 3200rpm) for a period of 4 to 6 minutes.

In some embodiments, the fiberizing mixture is: mechanical stirring, ultrasonic dispersion, ball milling and mixing, extruder mixing, vibration mixing and defoaming mixing; further, the fibrosis mixing mode is as follows: ball milling mixing, extruder mixing or mechanical stirring with a stirring speed of more than 3500 rpm; furthermore, the fiberization mixing mode is ball milling mixing and extruder mixing. The ball milling material mixing and the extruder material mixing can improve the fiberization degree of fiberizable polymer, and then can effectively improve the treatment effect of post-fiberization treatment.

In some embodiments, the fiberizing mixing means has a mixing time of greater than 10 min; in some embodiments, the fiberizing mixing mode adopts a pulse type mixing mode; further, the pulse type mixing mode is mixing for 1-3min, stopping for 0.5-1.5min, repeating the steps, and the total processing time is more than 10 min; furthermore, the total processing time of the pulse type mixing mode is 20-60 min; further, it is 25min-40 min.

In some embodiments, in step S1011, the active material and the conductive agent are mixed and stirred uniformly, and then the fiberizable polymer and the polymer additive are added.

The active substance and the conductive agent are uniformly mixed, and then the fiberizable polymer and the polymer additive are added, so that the mixing uniformity can be improved, the subsequent mixing burden is reduced, the processing time of a non-fiberizable mixing mode is reduced, and the problem that the fiberizable polymer is too early fiberized and the viscosity of the mixed material is increased to influence the uniformity of the mixed material is avoided.

Further, the active material and the conductive agent are uniformly mixed in the following manner: mixing in a mechanical stirring, ultrasonic dispersion, ball milling and mixing, extruder mixing, vibration mixing or defoaming mixing mode; preferably, a mechanical mixing mode is adopted for mixing; more preferably, mechanical mixing at a speed of > 2000rpm is used.

S1012: and (3) processing the anode mixed material by adopting a high-speed airflow shearing method to obtain anode fiberization powder.

The positive electrode mixed material is subjected to fiberization treatment by adopting a high-speed airflow shearing method, so that the positive electrode mixed material can be fully fiberized, uniformly dispersed fiberized powder with certain viscosity is obtained, the follow-up hot pressing is facilitated, the strength and toughness of the positive electrode diaphragm can be greatly improved, and the self-supporting flexible positive electrode diaphragm (namely the positive electrode diaphragm) is formed.

In some embodiments, in step S102, the mixture is subjected to high-speed airflow shearing by using an airflow pulverizer, and the processing parameters are as follows: the air flow speed is more than or equal to Mach 2.5, and the time is more than or equal to 5 min.

S1013: and carrying out hot pressing on the positive electrode fiberization powder to prepare a positive electrode membrane as a positive electrode layer.

Because the fiberization powder has higher fiberization degree, the fibers of the fiberization powder are mutually overlapped after hot pressing treatment to form a compact network structure, and further the anode diaphragm with higher strength and toughness can be formed.

The rolling frequency is not particularly limited, and may be adjusted according to actual requirements, and the parameters of each rolling may be the same or different, and all of them are understood to be within the protection scope of the present invention.

In some embodiments, step S1013 includes the steps of: preheating the rollers of the roller press to a preset temperature, adjusting a gap between the two rollers of the roller press, taking a proper amount of the fiberized powder, placing the fiberized powder on the rollers of the roller press, and rolling at a certain rolling speed to prepare the anode diaphragm with the required thickness.

In some embodiments, the positive electrode membrane sheet has a compacted density of 2.0-4.0 g/cc; further, the positive electrode membrane has a compacted density of 2.5 to 3.8 g/cc.

In some embodiments, the preheating temperature may be 50-200 ℃, preferably 100-; further, the preheating temperature is 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ or 160 ℃.

In some embodiments, the roller gap can be 0-150 μm, preferably 20-120 μm; further, the rolling gap is 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm or 80 μm.

In some embodiments, the rolling speed is 1-20 rpm; further, the rolling speed is 5-15 rpm; further, the rolling speed was 6rpm, 7rpm, 8rpm, 9rpm or 10 rpm.

S102: preparing a negative electrode layer; the relevant technical features of the negative electrode layer are as described above, and are not described herein again.

In some embodiments, the negative electrode layer is prepared using a dry process. The dry method for preparing the cathode layer can effectively avoid the use of solvent, reduce the complexity of operation, save the cost and avoid the influence on the performance of the pole piece caused by solvent residue.

In some embodiments, step S102 includes the steps of:

s1021: mixing the raw materials for forming the negative electrode layer, processing in a non-fiberizing mixing mode, and processing in a fiberizing mixing mode to obtain a negative electrode mixed material;

step S1021 is substantially synchronous with step S1011, except that the positive electrode layer material in step S1011 is replaced with the negative electrode material, which is described above and will not be described herein again.

S1022: and (3) performing fiberization treatment on the negative electrode mixed material by adopting a high-speed airflow shearing method to obtain negative electrode fiberized powder.

Step S1022 is substantially the same as step S1012, except that the positive electrode layer raw material in step S1012 is replaced with the negative electrode raw material, which is specifically described above and will not be described herein again.

S1023: and carrying out hot pressing on the negative electrode fiberization powder to prepare a negative electrode diaphragm as a negative electrode layer.

Step S1023 is substantially synchronous with step S1013, except that the positive electrode layer raw material in S1013 is replaced with a negative electrode raw material, which is described above and will not be described herein again.

In some embodiments, the negative electrode film sheet has a compacted density of 1.0 to 2.5 g/cc; further, the negative electrode film sheet has a compacted density of 1.3 to 2.0 g/cc.

S103: and loading the positive electrode layer and the negative electrode layer on two opposite surfaces of the current collector, and enabling the positive electrode layer, the current collector and the negative electrode layer to form an integrated structure.

In some embodiments, in step S103, the positive electrode layer and the negative electrode layer are rolled onto opposite sides of the current collector by a rolling method, so as to form a positive-negative integrated electrode sheet structure.

It can be understood that when the first conductive layer is arranged between the current collector and the positive electrode layer and the second conductive layer is arranged between the current collector and the negative electrode layer, the materials for forming the corresponding conductive layers can be coated on the two opposite surfaces of the current collector, and then the positive and negative electrode diaphragms are loaded on the surface containing the first conductive layer and the second conductive layer. Further, the first conductive layer and the second conductive layer contain a low-melting-point polymer therein.

The adhesion can be improved by arranging the first conducting layer and the second conducting layer, so that the firmness between the positive and negative electrode layers and the current collector can be improved, the first conducting layer and the second conducting layer contain low-melting-point polymers, the adhesion between the positive and negative electrode membranes and the conducting layers can be further improved, and the firmness between the positive and negative electrode membranes and the current collector is further improved.

In some embodiments, step S103 includes the steps of: and respectively placing the positive electrode diaphragm and the negative electrode diaphragm on two opposite surfaces of the current collector, arranging the positive electrode diaphragm and the negative electrode diaphragm in relative order, and rolling the positive electrode diaphragm and the negative electrode diaphragm by a preheated roller press at a certain rolling speed to realize the tight bonding of the positive electrode diaphragm and the negative electrode diaphragm with the current collector to prepare an integrated positive electrode plate and a negative electrode plate.

In some embodiments, the pre-heat temperature is 50-200 ℃; further, the preheating temperature is 100-180 ℃; further, the preheating temperature is 105 ℃, 110 ℃, 115 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃ or 160 ℃.

In some embodiments, the rolling speed is 3-15 rpm; further, the rolling speed is 5-12 rpm; further, the rolling speed was 6rpm, 7rpm, 8rpm, 9rpm or 10 rpm.

The pole piece prepared by the method has adhesive force, and the fiberized polymer can provide self-supporting force, so that the membrane can be self-supporting and flexible and bendable (as shown in figure 2), and the pole piece is prevented from being cracked and falling off in the rolling process. Compared with the common pole piece, the pole piece prepared by the method can realize higher compaction density and surface density, and is also beneficial to improving the energy density of the battery core.

The third aspect of the invention provides the pole piece prepared by the preparation method of the second aspect.

The fourth aspect of the present invention provides an electrical core, which includes a plurality of pole pieces connected in series, where the pole pieces are the pole pieces of the first aspect of the present invention or the pole pieces of the third aspect of the present invention.

In a fifth aspect, the present invention provides a battery, including the pole piece of the first aspect, the pole piece of the third aspect, or the battery cell of the fourth aspect.

In some embodiments, the battery is a liquid battery, a solid-state battery, a semi-solid state battery, a lithium sulfur battery, or a lithium air battery.

A sixth aspect of the invention provides an electronic product including the battery described above.

The present invention will be described below by way of specific examples, which are intended to be illustrative only and should not be construed as limiting the invention.

Example 1

(1) Shearing and mixing an active substance NCM (94% by mass) and a conductive agent SP (2% by mass) in a mechanical stirring manner at a stirring speed of 5000rpm for 5 min; adding a fiberized polymer PTFE (4% by mass) and mixing in a vibration mixing mode for 6min (pulse mixing is adopted, namely mixing for 1min, and mixing for 1min is carried out after stopping for 1 min). Shearing and mixing for 20min at the speed of 15000rpm by adopting a high-speed ball mill (pulse type stirring is also adopted), so that different materials are fully and uniformly dispersed, and a positive electrode mixed material with a certain bonding effect is generated; transferring the powder into a jet mill, and carrying out high-speed jet shearing to realize sufficient fiberization of PTFE and obtain fiberized powder with certain viscosity; preheating the rollers of the roller press to 150 ℃, adjusting the gap between the two rollers of the roller press to be 60 mu m, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 8rpm to prepare the self-supporting flexible anode membrane with the thickness of 55 mu m and the compaction density of 3.7 g/cc.

(2) An active material Gr (96.5% by mass), a conductive agent SP (1% by mass), and CNT are mixed

(0.5% by mass) mechanically stirring at 3000rpm for 6 min; then adding a fiberized polymer PTFE (2 percent by mass) and mixing in a vibration mixing mode for 8min (pulse stirring, namely stirring for 1min, stopping for 1min and then stirring for the next 1 min). Finally, shearing and mixing the mixture for 15min (pulse stirring is adopted) by a high-speed ball mill at the speed of 18000rpm, so that different materials are fully and uniformly dispersed and a certain bonding negative electrode mixed material is generated; further transferring the negative electrode mixed material into a jet mill, and carrying out high-speed jet shearing to realize sufficient fiberization of PTFE (polytetrafluoroethylene) and obtain fiberization powder with certain viscosity; preheating the rollers of the roller press to 160 ℃, adjusting the gap between the two rollers of the roller press to be 60 mu m, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 10rpm to prepare the self-supporting flexible negative electrode film with the thickness of 65 mu m and the compaction density of 1.7 g/cc.

(3) Respectively placing the rolled positive electrode diaphragm and the rolled negative electrode diaphragm on two sides of a current collector, relatively arranging the positive electrode diaphragm and the negative electrode diaphragm in order, and rolling by a roller press with the preheating completion temperature of 150 ℃ at the rolling speed of 8rpm and the gap of a roller wheel of 135 mu m to realize the tight bonding of the positive electrode diaphragm and the negative electrode diaphragm with the current collector; the current collector is a copper-aluminum composite current collector, the thickness of the current collector is 20 micrometers, and the overall thickness of the integrated positive and negative electrode plates is 138 micrometers, which is specifically shown in table 1. The pole piece is assembled into a battery to carry out electrochemical performance test, and the test results are shown in table 1 and figure 3.

Example 2

(1) Mixing an active substance LFP (90% by mass), a conductive agent SP (2% by mass) and active carbon (2% by mass) in a vibration mixing manner for 30 min; then adding the fiberized polymer PTFE (6 percent by mass) and shearing, stirring and mixing at a low speed of 1000rpm for 6min (pulse stirring, namely stirring for 1min, stopping for 1min and then stirring for the next 1 min). Finally, shearing and mixing at a high speed of 15000rpm for 20min (pulse stirring is also adopted), so that different materials are fully and uniformly dispersed, and a certain bonding effect is generated on the anode mixed material; further transferring the positive mixed material into a jet mill for high-speed jet shearing to realize full fiberization of PTFE and obtain fiberized powder with certain viscosity; preheating the rollers of the roller press to 150 ℃, adjusting the gap between the two rollers of the roller press to 70 μm, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 8rpm to prepare the self-supporting flexible anode membrane with the thickness of 75 μm and the compaction density of 2.7 g/cc.

(2) Mixing an active material Gr (85.5 mass percent), an active material SiOx (6 mass percent), a conductive agent SP (1 mass percent) and a CNT (1.5 mass percent) in a vibration mixing manner for 60 min; then adding a fiberized polymer PTFE (6 percent by mass) and mixing in a vibration mixing mode for 30 min. Finally, shearing and mixing for 15min at a high speed of 18000rpm in a mechanical stirring manner (pulse stirring is also adopted), so that different materials are fully and uniformly dispersed and a certain bonding effect is generated; further transferring the negative electrode mixed material into a jet mill, and carrying out high-speed jet shearing to realize sufficient fiberization of PTFE (polytetrafluoroethylene) and obtain fiberization powder with certain viscosity; preheating the rollers of the roller press to 160 ℃, adjusting the gap between the two rollers of the roller press to be 38um, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 9rpm to prepare the self-supporting flexible negative electrode film with the thickness of 43 mu m and the compaction density of 1.65 g/cc.

(3) Respectively placing the rolled positive electrode diaphragm and the rolled negative electrode diaphragm on two sides of a current collector, relatively arranging the positive electrode diaphragm and the negative electrode diaphragm in order, and rolling by a roller press with the preheating completion temperature of 140 ℃ at the rolling speed of 10rpm and the gap of a roller of 130 mu m to realize the tight bonding of the positive electrode diaphragm and the negative electrode diaphragm with the current collector; the current collector is carbon fiber paper with the thickness of 16 μm, and the integral thickness of the integrated positive and negative electrode plates is 132 μm, which is specifically shown in table 1. The pole piece is assembled into a battery to carry out electrochemical performance test, and the test result is shown in table 1.

Example 3

(1) Shearing and mixing an active material NCM (91.5% by mass) and a conductive agent rGO (2.5% by mass) at a stirring speed of 5000rpm for 5 min; then adding the fiberized polymer PTFE (4% by mass) and the polymer additive PVDF (2% by mass) to mix in a vibration mixing mode for 30min (pulse stirring is adopted, namely stirring is carried out for 2min, and stirring is carried out for the next 2min after pause is 1 min). Finally, mixing materials in an extruder mixing mode (the diameter of a screw is 30mm, the rotating speed of the screw is 300rpm, and the temperature of the extruder melt is 80 ℃), so that different materials are fully and uniformly dispersed and a certain bonding effect is generated for anode mixing; further transferring the positive mixed material into a jet mill for high-speed jet shearing to realize full fiberization of PTFE and obtain fiberized powder with certain viscosity; preheating the rollers of the roller press to 150 ℃, adjusting the gap between the two rollers of the roller press to be 100 mu m, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 8rpm to prepare the self-supporting flexible anode membrane with the thickness of 95 mu m and the compaction density of 3.6 g/cc.

(2) Shearing and mixing active substance Gr (95.5 wt%), conductive agent SP (1 wt%) and CNT (0.5 wt%) at a stirring speed of 6000rpm for 6 min; then adding the fiberization polymer PTFE (mass ratio is 2%) and the polymer additive CMC (mass ratio is 1%), mixing in a vibration mixing mode for 50min (pulse stirring is adopted, namely stirring is carried out for 1min, and stirring is carried out for the next 1min after stopping for 1 min). Finally, mixing materials in an extruder mixing mode (the diameter of a screw is 30mm, the rotating speed of the screw is 400rpm, and the temperature of the extruder melt is 90 ℃), so that different materials are fully and uniformly dispersed and certain bonding effect is generated; further transferring the negative electrode powder into a jet mill, and carrying out high-speed jet shearing to realize sufficient fiberization of PTFE (polytetrafluoroethylene) and obtain fiberization powder with certain viscosity; preheating the rollers of the roller press to 150 ℃, adjusting the gap between the two rollers of the roller press to be 115 mu m, placing a proper amount of the fiberized powder on the rollers of the roller press, and rolling at the rolling speed of 9rpm to prepare the self-supporting flexible negative electrode film with the thickness of 110 mu m and the compaction density of 1.65 g/cc.

(3) Respectively placing the rolled positive electrode diaphragm and the rolled negative electrode diaphragm on two sides of a current collector, relatively arranging the positive electrode diaphragm and the negative electrode diaphragm in order, rolling by a roller press with the preheating completion temperature of 111 ℃ at the rolling speed of 8rpm and the gap of a roller wheel of 221 mu m, and realizing the tight bonding of the positive electrode diaphragm and the negative electrode diaphragm with the current collector; the current collector is a stainless steel foil current collector, the thickness of the current collector is 21 micrometers, and the overall thickness of the integrated positive and negative electrode plates is 223 micrometers, which is specifically shown in table 1. The pole piece is assembled into a battery to carry out electrochemical performance test, and the test result is shown in table 1.

TABLE 1

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A pole piece, comprising:

2. The pole piece of claim 1, wherein a first conductive layer is disposed between the current collector and the positive electrode layer, and a second conductive layer is disposed between the current collector and the negative electrode layer.

3. The pole piece according to claim 1 or 2, wherein the positive electrode layer comprises the following components in percentage by mass: 0.5-20% of a fiberization polymer, 50-98% of a positive active substance, 0.5-10% of a conductive agent and 0-20% of a polymer additive;

the negative electrode layer comprises the following components in percentage by mass: 1-20% of a fiberization polymer, 60-98% of a negative electrode active material, 0.5-5% of a conductive agent and 0-15% of a polymer additive.

4. The pole piece of claim 3, wherein the fiberized polymer is fiberized polytetrafluoroethylene;

the positive electrode active material is selected from: one or more of ternary NMC positive electrode material, lithium cobaltate, lithium manganate and lithium iron phosphate;

the negative active material is selected from: one or more of graphite, silicon oxygen, and lithium titanate;

the conductive agent is selected from: one or more of Super-P, carbon black, Ketjen black, carbon nanotubes, graphene, activated carbon, and carbon nanofibers;

the polymer additive is selected from: one or more of polyvinylidene fluoride, sodium carboxymethylcellulose, polystyrene, styrene-butadiene rubber and polyacrylic acid.

5. A preparation method of a pole piece is characterized by comprising the following steps:

6. The production method according to claim 5, wherein the step of producing the positive-electrode layer includes the steps of:

carrying out hot pressing on the positive electrode fiberization powder to prepare a positive electrode membrane as a positive electrode layer;

the step of preparing the negative electrode layer comprises the following steps:

7. The method of claim 6, wherein the non-fiberizing mixing means is: vibrating the mixed materials or mechanically stirring at a stirring speed of less than or equal to 3500 rpm; and/or

The fiberization mixing mode is as follows: ball milling mixing, extruder mixing or mechanical stirring with a stirring speed of more than 3500 rpm; and/or

In the step of processing the anode mixed material or the cathode mixed material by adopting a high-speed airflow shearing method, the processing parameters are as follows: the air flow speed is more than or equal to Mach 2.5, and the time is more than or equal to 5 min.

8. The production method according to claim 6, wherein the positive electrode film sheet has a compacted density of 2.0 to 4.0g/cc and a thickness of 30 to 300 μm;

9. An electric core, characterized by comprising a plurality of pole pieces connected in series, wherein the pole pieces are the pole pieces of any one of claims 1 to 4 or the pole pieces prepared by the preparation method of any one of claims 5 to 8.

10. A battery, characterized by comprising the pole piece of any one of claims 1 to 4, or the pole piece prepared by the preparation method of any one of claims 5 to 8, or the battery cell of claim 9.