CN117616007A

CN117616007A - Pore-forming agent, positive electrode slurry, positive electrode plate substrate, battery monomer, preparation method of battery monomer, battery module, battery pack and power utilization device

Info

Publication number: CN117616007A
Application number: CN202280047881.5A
Authority: CN
Inventors: 云亮; 孙信; 吴李力; 董苗苗; 宋佩东
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2022-05-12
Filing date: 2022-05-12
Publication date: 2024-02-27
Also published as: WO2023216168A1

Abstract

The application discloses pore-forming agent, it includes center ion, acid radical ion and ligand molecule, and center ion is lithium ion, and the ligand molecule has the structure that formula I shows:wherein R is ¹ 、R ² Each independently selected from methyl or ethyl, R ³ Independently selected from alkyl groups having 1 to 11 carbon atoms.

Description

Pore-forming agent, positive electrode slurry, positive electrode plate substrate, battery monomer, preparation method of battery monomer, battery module, battery pack and power utilization device

Technical Field

The application relates to the technical field of secondary batteries, in particular to a pore-forming agent and a preparation method thereof, positive electrode slurry, a positive electrode plate substrate and a preparation method thereof, an electrode assembly, a battery monomer and a preparation method thereof, a battery module, a battery pack and an electric device.

Background

The statements herein merely provide background information related to the present application and may not necessarily constitute prior art.

With the acceleration of life pace and the development of various electronic products such as smart phones, tablet computers, intelligent wearing, electric tools, electric automobiles and the like, the requirements of customers and markets on the performance of lithium ion batteries are higher and higher. Particularly, in order to realize long-time cruising of an electric automobile, a lithium battery which has the capability of competing with a fuel oil automobile and has high capacity, high energy density and excellent cycle performance is urgently required to be developed.

In order to increase the capacity and energy density of the battery, researchers have adopted thick coating slurry to prepare a thick electrode, and doped pore formers in the slurry to enable the electrode to have proper porosity, so that the electrode has high energy density while having high capacity. However, the pores prepared by the ammonium bicarbonate and azo pore formers which are widely adopted at present are nanoscale pores, the pore closing phenomenon is easy to occur in the pole piece rolling process, and the nanoscale pores do not have the liquid phase transmission capacity, so once the pore closing occurs, the energy density cannot be effectively improved, the tortuosity of the pole piece is increased, the characteristic thickness of the pole piece is reduced, and the gram capacity is exerted to be low.

Disclosure of Invention

In view of the above problems, the application provides a pore-forming agent, positive electrode slurry, a positive electrode plate substrate, a battery assembly, a battery monomer, a preparation method thereof, a battery module, a battery pack and an electric device.

In a first aspect, the present application provides a pore former comprising a central ion, an acid ion, and a ligand molecule, the central ion being a lithium ion, the ligand molecule having a structure represented by formula I:

Wherein R is ¹ 、R ² Each independently selected from methyl or ethyl, R ³ Independently selected from alkyl groups having 1 to 11 carbon atoms.

According to the technical scheme, ligand molecules shown in the formula I are complexed with the lithium ion center, and the prepared pore-forming agent can be decomposed under certain conditions, such as when being heated and coated, gas is generated, so that a plurality of air passages are distributed in a final active material layer, residual lithium salt can be dissolved in electrolyte through the air passages, micron-level pores are formed in situ, thereby accelerating ion transmission, reducing liquid phase polarization, increasing gram capacity exertion of electrode materials, improving infiltration time of electrodes, being beneficial to backflow of electrolyte, realizing electrochemical performance exertion of which is more than twice of electrode thickness and normal, reducing use of metal foil, improving energy density and reducing cost.

In some embodiments, the acid ion is a monovalent anion.

In some embodiments, the acid ion comprises PF ₆ ^- 、BOB ^- 、ODFB ^- 、TFSI ^- 、FSI ^- 、TNFSI ^- 、PO ₂ F ₂ ^- One or more of the following. The full names of the acid radical ions are respectively as follows: hexafluorophosphate ion, bis (oxalato) borate ion, difluoro (oxalato) borate ion, bis (trifluoromethanesulfonyl) iminoion, bis (fluorosulfonyl) ) Iminium ion, super delocalized sulfonium ion, difluoroborate ion. The lithium salt of the acid radical ions has good electrochemical property and is often used as electrolyte, so that the acid radical ions are selected as anions of the pore-forming agent, after the acid radical ions are dissolved in the electrolyte, the required pores can be generated in situ, the electrolyte can be provided for the electrolyte, and the cost is effectively reduced.

In some embodiments, the R ³ Independently selected from alkyl groups having 1 to 6 carbon atoms.

In some embodiments, the R ¹ 、R ² Methyl, said R is ³ Selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl.

In some embodiments, the R ¹ 、R ² Methyl, said R is ³ Is n-hexyl.

R ¹ And R is ² The selection of (3) not only relates to the coordination capability of ligand molecules and lithium ions, and influences the properties such as particle size and stability of the finished pore-forming agent, but also relates to whether the pore-forming agent can be thoroughly decomposed as expected during heating to form an air passage so that the electrolyte dissolves the rest lithium salt. Through extensive research, R ¹ And R is ² In the above embodiment, the ligand molecule coordination ability and the decomposition and gas generation ability during heating can be well combined, and the toxicity is low.

In some embodiments, the pore former has an average particle size in the range of 10 μm to 200 μm. The particle size of the pore-forming agent is controlled within a certain range, so that pores with more proper sizes can be formed, and the energy density of the electrode is reduced without causing closed pores.

In some embodiments, the ratio of the amounts of the species of the center ion, the acid ion, and the ligand molecule is 1:1 (1-4).

In a second aspect of the present application, a positive electrode slurry is provided that includes a positive electrode active material, an auxiliary agent, a solvent, and a pore-forming agent as described in one or more of the foregoing embodiments.

In some embodiments, in the positive electrode slurry, the mass percentage of the pore-forming agent in the solid component is 1% -10%.

The mass percentage of the pore-forming agent in the positive electrode slurry is related to the porosity of the finished electrode sheet, and the proper amount of the pore-forming agent can accelerate ion transmission to reduce liquid phase polarization, increase gram capacity exertion of electrode materials, improve electrode infiltration time and not excessively influence the energy density of the electrode.

In some embodiments, the positive electrode active material includes Li _a Ni _x Co _y Mn _z M ¹ _(1-x-y-z) O ₂ 、vLi[Li _1/3 Mn _2/3 ]O ₂ ·(1–v)LiM ² O ₂ Or Li (lithium) _1-w CoO ₂ One or more of the following;

wherein a is more than or equal to 0.9 and less than or equal to 1.2,0.5, x is more than or equal to 0.98,0 and y is more than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.2, M ¹ Each occurrence is independently selected from Al, mg, zn, zr, ti or Fe;

0≤v≤1，M ² each occurrence is independently selected from Ni, co or Mn;

0≤w≤0.5。

the pore-forming agent prepared by the method is more suitable for the positive electrode active material, and the pore-forming agent and the positive electrode active material are matched for use, so that the gram capacity of the positive electrode active material can be better exerted.

In some embodiments, the auxiliary agent includes one or more of a magnetic modifying material, a thickener, a conductive agent, a binder, and a dispersant.

In some embodiments, the positive electrode slurry has a viscosity of 6000 mPa-s to 15000 mPa-s at 25±0.5 ℃.

In some embodiments, the positive electrode slurry has a solids content of 68% to 76%.

The proper viscosity and solid content can enable the pore-forming agent to be distributed in the positive electrode slurry more uniformly, so that more uniform pores are formed, and the influence on the physical strength, gram capacity exertion and the like of the electrode caused by aggregation of the pore-forming agent is avoided.

In a third aspect of the present application, there is provided a positive electrode sheet substrate, which includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, where the positive electrode active material layer is formed by curing the positive electrode slurry in one or more of the foregoing embodiments.

In some embodiments, the positive electrode active material layer has a thickness of 120 μm to 400 μm. The thickness of the positive electrode active material layer is limited to a proper range, and is more matched with the pore-forming agent, so that higher gram capacity and characteristic thickness can be exerted.

In some embodiments, the ratio of the average particle diameter of the pore-forming agent to the thickness of the positive electrode active material layer ranges from 1 (5 to 7). The particle size of the pore-forming agent and the thickness of the positive electrode active material layer are controlled within a certain proportion range, so that the electrode gram capacity can be effectively improved, the electrode infiltration time is improved, and adverse effects on the energy density and the physical strength of the electrode are avoided as much as possible.

In a fourth aspect of the present application, an electrode assembly is provided, which includes a negative electrode sheet, a separator, and the positive electrode sheet substrate according to any of the foregoing embodiments, wherein the separator is disposed between the negative electrode sheet and the positive electrode sheet substrate.

In a fifth aspect of the present application, a battery cell is provided, which includes a negative electrode plate, a separator, and a positive electrode plate that are stacked and distributed, where the separator is disposed between the negative electrode plate and the positive electrode plate;

The positive electrode plate is prepared by the contact treatment of the positive electrode plate substrate and electrolyte according to any of the previous embodiments, and the positive electrode plate has a porous structure.

In some embodiments, the concentration of lithium ions in the electrolyte is 0mol/L to 1mol/L, and the solvent of the electrolyte includes one or more of dimethyl carbonate, diethyl carbonate, methylethyl carbonate, and polycarbonate. The pore-forming agent provided by the application can dissolve the lithium salt left after ligand molecule decomposition in electrolyte in situ to form pores, so that the concentration of lithium ions in the electrolyte adopted by the application needs to be smaller than that of conventional electrolyte (the concentration of lithium ions in conventional electrolyte is about 1.2 mol/L), even the electrolyte-free pure solvent can be adopted for pouring, the electrolyte is formed after the lithium salt is dissolved, the concentration of lithium ions in the electrolyte is maintained in a proper range, and adverse effects on the cycle performance of a battery due to overhigh concentration of the lithium ions are avoided.

In some embodiments, the positive electrode sheet has a porosity of 25% to 40%. The porosity of the pole piece is maintained in a proper range, the wettability of the electrode, the liquid phase transmission of ions and gram capacity exertion can be obviously improved on the premise of not influencing the energy density of the electrode, and particularly for thicker electrodes, the pore-forming agent can provide relatively higher porosity, and the wettability of the thick electrode is greatly improved compared with the prior art, so that the thick electrode can have larger characteristic thickness.

In some embodiments, the pore size of the positive electrode sheet is 60 μm to 200 μm. The aperture in the positive pole piece is set in a proper range, and the electric performance, the infiltration performance and the physical strength of the pole piece can be considered.

In some embodiments, the positive electrode sheet has a compacted density of 2.9g/cm ³ ～3.5g/cm ³ . The proper compacted density is in fact related to the porosity of the pole piece and thus also to the gram capacity exertion and energy density of the pole piece.

In a sixth aspect of the present application, there is also provided a battery module comprising the battery cell according to any one of the preceding embodiments.

In a seventh aspect of the present application, a battery pack is provided, which includes the aforementioned battery module.

In an eighth aspect of the present application, an electrical device is provided, which includes one or more of the battery cells, the battery modules, and the battery packs described in the foregoing embodiments.

In a ninth aspect of the present application, there is provided a method for preparing a pore-forming agent according to any one of the preceding embodiments, which includes method a or method B:

the method A comprises the following steps:

mixing acid with the ligand molecules to prepare a mixture, reacting the mixture with lithium carbonate, performing solid-liquid separation after the reaction is finished, collecting a solid phase, and drying;

The method B comprises the following steps:

dissolving lithium salt in a solvent to prepare a lithium salt solution, reacting the lithium salt solution with the ligand molecules, performing solid-liquid separation after the reaction is finished, collecting a solid phase, and drying.

In the method A, acid and ligand molecules are premixed, then anion exchange is carried out on the acid and the ligand molecules through strong acid to prepare lithium salt, and meanwhile, the lithium salt is coordinated with the ligand molecules to form a pore-forming agent, so that the prepared pore-forming agent has high purity and accurate particle size control on the pore-forming agent due to the atomic-level chemical change; the method B has the advantage of wide application range.

In some embodiments, the acid comprises one or more of hexafluorophosphoric acid and difluorophosphoric acid; the lithium salt comprises LiPF ₆ 、LiBOB、LiODFB、LiTFSI、LiFSI、LiTNFSI、LiPO ₂ F ₂ The solvent includes one or more of dimethyl carbonate, diethyl carbonate, polycarbonate, and fluoroethylene carbonate.

In some embodiments, in method A, the ratio of the amount of the acid to the amount of the ligand molecular species is 1 (1-10). The proper dosage ratio can ensure that the ligand molecules in the mixture are proper in number, smoothly coordinate with lithium ions and form particles with proper particle sizes.

In some embodiments, in method a, the ratio of the amount of acid to the amount of material of the lithium carbonate is 2 (0.8-1.2).

In some embodiments, in method B, the ratio of the amount of lithium salt to the amount of substance of the ligand molecule is 1 (2-5). The ligand molecule can be successfully coordinated with lithium ions by proper dosage ratio, and particles with proper particle size are formed.

In some embodiments, in method B, the lithium ion concentration in the lithium salt solution is between 0.5mol/L and 1mol/L. The appropriate lithium ion concentration enables better coordination to occur, forming pore formers of appropriate particle size.

In a tenth aspect of the present application, there is further provided a method for preparing the positive electrode sheet substrate according to any one of the foregoing embodiments, including the steps of:

the positive electrode slurry according to one or more of the previous embodiments is coated on at least one surface of the positive electrode current collector, dried, and pressed.

In some embodiments, the coating thickness of the positive electrode slurry is 250 μm to 800 μm. The appropriate coating thickness enables formation of a positive electrode active material layer of an appropriate thickness after pressing.

In some embodiments, the temperature at which the positive electrode slurry is applied is 80 ℃ to 120 ℃. The temperature of the anode slurry is controlled in a proper range during coating, ligand molecules in the pore-forming agent can be thoroughly decomposed to form an air passage, and the stability of other components in the slurry is not affected.

In an eleventh aspect of the present application, there is provided a method for preparing the foregoing battery cell, including the steps of: the electrolyte is injected into a battery case in which the aforementioned electrode assembly is mounted.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description and drawings, and from the claims.

Drawings

For a better description and illustration of embodiments or examples of those applications disclosed herein, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be construed as limiting the scope of any of the disclosed applications, the presently described embodiments or examples, and the presently understood best mode of carrying out these applications. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

fig. 1 is a schematic view of a battery cell according to an embodiment of the present application.

Fig. 2 is an exploded view of the battery cell of the embodiment of the present application shown in fig. 1.

Fig. 3 is a schematic view of a battery module according to an embodiment of the present application.

Fig. 4 is a schematic view of a battery pack according to an embodiment of the present application.

Fig. 5 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 4.

Fig. 6 is a schematic view of an electric device in which a battery cell according to an embodiment of the present application is used as a power source.

Reference numerals illustrate:

1, a battery pack; 2, upper box body; 3, lower box body; 4, a battery module; 5, a battery cell; 51 a housing; 52 electrode assembly; 53 cover plates.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

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 application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Hereinafter, embodiments of pore formers, positive electrode slurry, positive electrode tab substrates, electrode assemblies, battery cells, methods of manufacturing the same, battery modules, battery packs, and electrical devices of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art. Furthermore, the drawings and the following description are provided for a full understanding of the present application by those skilled in the art, and are not intended to limit the subject matter recited in the claims.

The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In this application, unless otherwise indicated, the numerical ranges "a-b" represent shorthand representations of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is only a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.

All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.

All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

The electrode pole piece is often provided with a certain pore, the size of the pore has direct influence on the performance of the pole piece, and the too large pore can lead to the loose contact among particles in the pole piece material, the far transmission paths of lithium ions and electrons, large resistance and large energy loss; too small pores can lead to difficult pole piece infiltration, thereby resulting in poor battery cycle life and rate capability. In addition to adjusting the particle size and ratio of the components in the slurry to control the porosity in the finished pole piece, the most common is the addition of pore formers.

The prior pore-forming agent mainly comprises ammonium bicarbonate and azo compounds, and the ammonium bicarbonate and the azo compounds can be decomposed when being heated during coating slurry, so that pores are formed, however, most of the pore-forming agents are nano-scale pores formed by decomposition, the pore-forming agent does not have liquid phase mass transfer capability, and a pore-closing phenomenon can occur due to the fact that the pore-forming agent is too small in size in a rolling process, so that not only can effective pores be formed, but also the tortuosity of an electrode can be increased, the characteristic thickness of the electrode is reduced, and the gram capacity is exerted to be low.

Aiming at the problem of ubiquitous pore-forming agents in the prior art, in a first aspect, the application provides a pore-forming agent which comprises a center ion, an acid radical ion and a ligand molecule, wherein the center ion is lithium ion, and the ligand molecule has a structure shown in a formula I:

In some embodiments, R ³ The number of carbon atoms of (2), 3, 4, 5, 6, 7, 8, 9 or 10, for example.

In this application, the term "alkyl" refers to a saturated hydrocarbon containing primary (positive) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or a combination thereof. Phrases containing this term, e.g., "C ₁ ～C ₁₁ Alkyl "means an alkyl group containing 1 to 6 carbon atoms, which at each occurrence may be, independently of one another, C ₁ Alkyl, C ₂ Alkyl, C ₃ Alkyl, C ₄ Alkyl, C ₅ Alkyl, C ₆ Alkyl, C ₇ Alkyl, C ₈ Alkyl, C ₉ Alkyl, C ₁₀ Alkyl, C ₁₁ An alkyl group. Suitable examples include, but are not limited to: methyl (Me, -CH) ₃ ) Ethyl (Et, -CH) ₂ CH ₃ ) 1-propyl (n-Pr, n-propyl, -CH ₂ CH ₂ CH ₃ ) 2-propyl (i-Pr, i-propyl, isopropyl, -CH (CH) ₃ ) ₂ ) 1-butyl (n-Bu, n-butyl, -CH) ₂ CH ₂ CH ₂ CH ₃ ) 2-methyl-1-propyl (i-Bu, i-butyl, -CH) ₂ CH(CH ₃ ) ₂ ) 2-butyl (s-Bu, s-butyl, -CH (CH) ₃ )CH ₂ CH ₃ ) 2-methyl-2-propyl (t-Bu, t-butyl, -C (CH) ₃ ) ₃ ) 1-pentyl (n-pentyl, -CH) ₂ CH ₂ CH ₂ CH ₂ CH ₃ ) 2-pentyl radicalCH (CH 3) CH2CH2CH 3), 3-pentyl (-CH (CH) ₂ CH ₃ ) ₂ ) 2-methyl-2-butyl (-C (CH) ₃ ) ₂ CH ₂ CH ₃ ) 3-methyl-2-butyl (-CH (CH) ₃ )CH(CH ₃ ) ₂ ) 3-methyl-1-butyl (-CH) ₂ CH ₂ CH(CH ₃ ) ₂ ) 2-methyl-1-butyl (-CH) ₂ CH(CH ₃ )CH ₂ CH ₃ ) 1-hexyl (-CH) ₂ CH ₂ CH ₂ CH ₂ CH ₂ CH ₃ ) 2-hexyl (-CH (CH) ₃ )CH ₂ CH ₂ CH ₂ CH ₃ ) 3-hexyl (-CH (CH) ₂ CH ₃ )(CH ₂ CH ₂ CH ₃ ) 2-methyl-2-pentyl (-C (CH) ₃ ) ₂ CH ₂ CH ₂ CH ₃ ) 3-methyl-2-pentyl (-CH (CH) ₃ )CH(CH ₃ )CH ₂ CH ₃ ) 4-methyl-2-pentyl (-CH (CH) ₃ )CH ₂ CH(CH ₃ ) ₂ ) 3-methyl-3-pentyl (-C (CH) ₃ )(CH ₂ CH ₃ ) ₂ ) 2-methyl-3-pentyl (-CH (CH) ₂ CH ₃ )CH(CH ₃ ) ₂ ) 2, 3-dimethyl-2-butyl (-C (CH) ₃ ) ₂ CH(CH ₃ ) ₂ ) And 3, 3-dimethyl-2-butyl (-CH (CH) ₃ )C(CH ₃ ) ₃ 。

In some embodiments, the acid ion is a monovalent anion.

In some embodiments, the acid ion comprises PF ₆ ^- 、BOB ^- 、ODFB ^- 、TFSI ^- 、FSI ^- 、TNFSI ^- 、PO ₂ F ₂ ^- One or more of the following. The full names of the acid radical ions are respectively as follows: hexafluorophosphate ions, bis (oxalato) borate ions, difluoro (oxalato) borate ions, bis (trifluoromethanesulfonyl) imide ions, bis (fluorosulfonyl) imide ions, super delocalized sulfonimide ions, difluoro borate ions. The lithium salt of the acid radical ions has good electrochemical property and is often used as electrolyte, so that the acid radical ions are selected as anions of the pore-forming agent, after the acid radical ions are dissolved in the electrolyte, the required pores can be generated in situ, the electrolyte can be provided for the electrolyte, and the cost is effectively reduced.

In some embodiments, R ³ Independently selected from alkyl groups having 1 to 6 carbon atoms. Preferably, R ³ Selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl, further preferably R ³ Is n-hexyl.

In some embodiments, R ¹ 、R ² Is methyl, R ³ Selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl.

In some embodiments, R ¹ 、R ² Is methyl, R ³ Is n-hexyl.

R ¹ And R is ² Not only the coordination ability of ligand molecules and lithium ions is concerned, but also the particle size, the stability and the like of the finished product of the pore-forming agent are influenced The nature, but also whether the pore-forming agent can decompose thoroughly as expected upon heating, forming gas channels so that the electrolyte dissolves the remaining lithium salt. Through extensive research, R ¹ And R is ² The above limitation is made to have a low toxicity while well combining the coordination ability of the ligand molecule and the decomposition/gassing ability upon heating.

In some embodiments, the pore former has an average particle size in the range of 10 μm to 200 μm. The "average particle diameter range" herein means a distribution range of the volume average particle diameter Dv 50. The volume average particle diameter Dv50 is a value known in the art and means an average particle diameter corresponding to 50% of particles in the volume distribution, and can be measured by an instrument and a method known in the art. For example, reference may be made to GB/T19077-2016 particle size distribution laser diffraction, conveniently using a laser particle size analyzer, such as Mastersizer 2000E, of Markov instruments, UK. .

In some embodiments, the average particle size of the pore former can be, for example, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 155 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 185 μm, 190 μm, or 195 μm. The particle size of the pore-forming agent is controlled within a certain range, so that pores with more proper sizes can be formed, and the energy density of the electrode is reduced without causing closed pores.

In some embodiments, the ratio of the amounts of the species of the center ion, the acid ion, and the ligand molecule in the pore former is 1:1 (1-4). The ratio of the amounts of the three substances may also be, for example, 1:1:2 or 1:1:3.

In a second aspect of the present application, a positive electrode slurry is provided that includes a positive electrode active material, an auxiliary agent, a solvent, and a pore former of one or more of the foregoing embodiments.

In some embodiments, the pore-forming agent is present in the positive electrode slurry in an amount of 1% to 10% by mass of the solid component.

In some embodiments, the mass percent of the pore former in the solid component in the positive electrode slurry may also be, for example, 3%, 4%, 6%, 7%, 8%, or 9%.

0≤v≤1，M ² each occurrence is independently selected from Ni, co or Mn;

0≤w≤0.5。

in some embodiments, a may also be, for example, 1.0 or 1.1.

In some embodiments, x may also be, for example, 0.6, 0.7, 0.8, or 0.9.

In some embodiments, y may also be, for example, 0.1 or 0.2.

In some embodiments, z may also be, for example, 0.05, 0.1, or 0.15.

In some embodiments, v may also be, for example, 0.2, 0.4, 0.6, or 0.8.

In some embodiments, w may also be, for example, 0.1, 0.2, 0.3, or 0.4.

In some embodiments, the positive electrode active material is LiNi _0.96 Co _0.02 Mn _0.02 O ₂ 。

In some embodiments, the positive electrode active material is 0.5Li [ Li ] _1/3 Mn _2/3 ]O ₂ ·0.5LiNiO ₂ 。

In some embodiments, the positive electrode slurry has a viscosity of 6000 mPas to 15000 mPas at 25+ -0.5 ℃. The viscosity of the positive electrode slurry at 25.+ -. 0.5 ℃ may be 7000 mPas, 8000 mPas, 9000 mPas, 10000 mPas, 11000 mPas, 12000 mPas, 13000 mPas or 14000 mPas, for example.

In some embodiments, the positive electrode slurry has a solids content of 68% to 76%. The solid content of the positive electrode slurry may be, for example, 70%, 72%, or 74%.

In a third aspect of the present application, there is provided a positive electrode sheet substrate including a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer being formed by curing the positive electrode slurry in one or more of the foregoing embodiments.

In some embodiments, the thickness of the positive electrode active material layer is 120 μm to 400 μm. The thickness of the positive electrode active material may also be, for example, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, or 380 μm. The thickness of the positive electrode active material layer is limited to a proper range, and is more matched with the pore-forming agent, so that higher gram capacity and characteristic thickness can be exerted.

In some embodiments, the ratio of the average particle size of the pore-forming agent to the thickness of the positive electrode active material layer ranges from 1 (5 to 7). The ratio of the average particle diameter of the pore-forming agent to the thickness of the positive electrode active material layer may also be, for example, 1:5.5, 1:6, or 1:6.5. The particle size of the pore-forming agent and the thickness of the positive electrode active material layer are controlled within a certain proportion range, so that the electrode gram capacity can be effectively improved, the electrode infiltration time is improved, and adverse effects on the energy density and the physical strength of the electrode are avoided as much as possible.

In a fourth aspect of the present application, an electrode assembly is provided, which includes a negative electrode sheet, a separator, and the positive electrode sheet substrate of any of the foregoing embodiments, which are stacked and distributed, the separator being disposed between the negative electrode sheet and the positive electrode sheet substrate.

the positive plate is prepared by the contact treatment of the positive plate substrate and electrolyte in any embodiment of the invention, and the positive plate has a porous structure.

In some embodiments, the concentration of lithium ions in the electrolyte is 0mol/L to 1mol/L, and the solvent of the electrolyte includes one or more of dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and polycarbonate. The concentration of lithium ions in the electrolyte may be, for example, 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L or 0.9mol/L, and preferably 0.1mol/L to 0.5mol/L. The pore-forming agent provided by the application can dissolve the lithium salt left after ligand molecule decomposition in electrolyte in situ to form pores, so that the concentration of lithium ions in the electrolyte adopted by the application needs to be smaller than that of conventional electrolyte (the concentration of lithium ions in conventional electrolyte is about 1.2 mol/L), even the electrolyte-free pure solvent can be adopted for pouring, the electrolyte is formed after the lithium salt is dissolved, the concentration of lithium ions in the electrolyte is maintained in a proper range, and adverse effects on the cycle performance of a battery due to overhigh concentration of the lithium ions are avoided.

In some embodiments, the positive electrode sheet has a porosity of 25% to 40%. The porosity of the positive electrode sheet may be, for example, 26%, 28%, 30%, 32%, 34%, 36% or 38%, and preferably 37% to 40%. The porosity of the pole piece is maintained in a proper range, the wettability of the electrode, the liquid phase transmission of ions and gram capacity exertion can be obviously improved on the premise of not influencing the energy density of the electrode, and particularly for thicker electrodes, the pore-forming agent can provide relatively higher porosity (37% -40%), and compared with the traditional technology, the wettability of the thick electrode is greatly improved, so that the thick electrode can have larger characteristic thickness.

In some embodiments, the pore size of the positive electrode sheet is 60 μm to 200 μm. The pore diameter of the positive electrode sheet may be, for example, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm or 190 μm. The pore diameter of the positive electrode sheet refers to the average pore diameter of the positive electrode sheet, and an exemplary test method can refer to the standard GB/T19587-2017 of measuring the specific surface area of solid substances by a gas adsorption BET method, and the solid material pore diameter distribution and the porosity of the solid material by a GB/T21650.2-2008 mercury intrusion method and a gas adsorption method, namely the 2 nd part: the gas adsorption method analyzes the mesopores and macropores. The average pore size of the positive electrode sheet may be tested, for example, using the U.S. microphone micromeritics TriStar II 3020 instrument. The average pore diameter in the positive electrode plate is set in a proper range, so that the electric performance, the infiltration performance and the physical strength of the plate can be considered.

In some embodiments, the positive electrode sheet has a compacted density of 2.9g/cm ³ ～3.5g/cm ³ The compacted density of the positive electrode sheet may be, for example, 3g/cm ³ 、3.1g/cm ³ 、3.2g/cm ³ 、3.3g/cm ³ Or 3.4g/cm ³ . Suitable compacted densities are also related to gram capacity exertion and energy density of the pole pieces.

In a sixth aspect of the present application, there is also provided a battery module comprising the battery cell of any one of the embodiments described above.

In an eighth aspect of the present application, an electrical device is provided that includes one or more of the battery cells of the foregoing embodiments, the foregoing battery modules, and the foregoing battery packs.

In a ninth aspect of the present application, there is provided a method for preparing a pore-forming agent according to any one of the preceding embodiments, comprising method a or method B:

the method A comprises the following steps:

mixing acid with ligand molecules to prepare a mixture, reacting the mixture with lithium carbonate, separating solid from liquid after the reaction is finished, collecting solid phase, and drying;

the method B comprises the following steps:

dissolving lithium salt in a solvent to prepare a lithium salt solution, reacting the lithium salt solution with ligand molecules, performing solid-liquid separation after the reaction is finished, collecting a solid phase, and drying.

In the method A, acid and ligand molecules are premixed, then anion exchange is carried out on the acid and the ligand molecules through strong acid to prepare lithium salt, and meanwhile, the lithium salt is coordinated with the ligand molecules to form a pore-forming agent, so that the prepared pore-forming agent has high purity due to the atomic-level chemical change, and the particle size of the pore-forming agent is accurately controlled; the method B has the advantage of wide application range.

In some embodiments, in method A, the ratio of the amount of acid to the amount of ligand molecular species is 1 (1-10). The ratio of the amount of acid to the ligand molecular species may also be, for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8 or 1:9. The proper dosage ratio can ensure that the ligand molecules in the mixture are proper in number, smoothly coordinate with lithium ions and form particles with proper particle sizes.

In some embodiments, the ratio of the amount of acid to the amount of lithium carbonate material in method A is 2 (0.8-1.2). The ratio of the amount of acid to the amount of material of lithium carbonate may also be, for example, 2:0.9, 2:1 or 2:1.1.

In some embodiments, in method a, the temperature of the mixture is reacted with lithium carbonate is between 40 ℃ and 50 ℃ for a period of between 0.5h and 3h. The temperature at which the mixture reacts with lithium carbonate may also be, for example, 42 ℃, 44 ℃, 46 ℃ or 48 ℃, and the reaction time may also be, for example, 1h, 1.5h, 2h or 2.5h. The ion exchange reaction is more thorough due to the proper reaction temperature and reaction time.

In some embodiments, in method a, the drying is at a temperature of 20 ℃ to 50 ℃ for a time of 80 hours to 150 hours. The drying temperature may also be, for example, 25 ℃, 30 ℃, 35 ℃, 40 ℃ or 45 ℃ and the time may be, for example, 100 hours, 120 hours or 140 hours. Suitable drying temperatures and drying times can adjust the particle size of the pore former to the desired range.

In some embodiments, the ratio of the amount of lithium salt to the amount of substance of the ligand molecule in method B is 1 (2-5). The ratio of the amount of lithium salt to the substance of the ligand molecule may also be, for example, 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5. The ligand molecule can be successfully coordinated with lithium ions by proper dosage ratio, and particles with proper particle size are formed.

In some embodiments, in method B, the lithium ion concentration in the lithium salt solution is between 0.5mol/L and 1mol/L. The lithium ion concentration in the lithium salt solution may also be, for example, 0.6mol/L, 0.7mol/L, 0.8mol/L or 0.9mol/L. The appropriate lithium ion concentration enables better coordination to occur, forming pore formers of appropriate particle size.

In some embodiments, in method B, the lithium salt solution is reacted with the ligand molecule at a temperature of 40 ℃ to 50 ℃ for a time of 0.5h to 3h. The temperature at which the lithium salt solution reacts with the ligand molecule may also be, for example, 42 ℃, 44 ℃, 46 ℃ or 48 ℃ and the reaction time may also be, for example, 1h, 1.5h, 2h or 2.5h. The proper reaction temperature and reaction time can lead the complexation reaction to be more thorough.

In some embodiments, in method B, the drying is at a temperature of 20 ℃ to 50 ℃ for a time of 80 hours to 150 hours. The drying temperature may also be, for example, 25 ℃, 30 ℃, 35 ℃, 40 ℃ or 45 ℃ and the time may be, for example, 100 hours, 120 hours or 140 hours. Suitable drying temperatures and drying times can adjust the particle size of the pore former to the desired range.

In a tenth aspect of the present application, there is also provided a method for preparing the positive electrode sheet substrate according to any one of the foregoing embodiments, including the steps of:

the positive electrode slurry of one or more of the previous embodiments is coated on at least one surface of the positive electrode current collector, dried, and pressed.

In some embodiments, the coating thickness of the positive electrode slurry is 250 μm to 800 μm. The coating thickness of the positive electrode slurry may also be 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm or 750 μm, for example. The appropriate coating thickness enables formation of a positive electrode active material layer of an appropriate thickness after pressing.

In some embodiments, the temperature at which the positive electrode slurry is applied is 80 ℃ to 120 ℃. The temperature at the time of coating the positive electrode slurry may be, for example, 90 ℃, 100 ℃, or 110 ℃. The temperature of the anode slurry is controlled in a proper range during coating, ligand molecules in the pore-forming agent can be thoroughly decomposed to form an air passage, and the stability of other components in the slurry is not affected.

In an eleventh aspect of the present application, there is provided a method for preparing the foregoing battery cell, including the steps of: electrolyte is injected into a battery case in which the aforementioned electrode assembly is mounted.

In addition, pore formers, positive electrode slurry, positive electrode tab substrates, electrode assemblies, battery cells, methods of making the same, battery modules, battery packs, and electrical devices of the present application are described below with appropriate reference to the accompanying drawings.

In one embodiment of the present application, a battery cell is provided.

Typically, the battery cell includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.

[ Positive electrode sheet ]

The positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises the pore-forming agent of the first aspect of the application.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

In some embodiments, the positive current collector may employ a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the positive electrode active material in the positive electrode active material layer may employ a positive electrode active material for a battery, which is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (e.g., liCoO) ₂ ) Lithium nickel oxide (e.g. LiNiO) ₂ ) Lithium manganese oxide (e.g. LiMnO ₂ 、LiMn ₂ O ₄ ) Lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi) _1/3 Co _1/3 Mn _1/3 O ₂ (may also be abbreviated asNCM ₃₃₃ )、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (also referred to as NCM) ₅₂₃ )、LiNi _0.5 Co _0.25 Mn _0.25 O ₂ (also referred to as NCM) ₂₁₁ )、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (also referred to as NCM) ₆₂₂ )、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (also referred to as NCM) ₈₁₁ ) Lithium nickel cobalt aluminum oxide (e.g. LiNi _0.85 Co _0.15 Al _0.05 O ₂ ) And at least one of its modified compounds and the like. Examples of olivine structured lithium-containing phosphates may include, but are not limited to, lithium iron phosphate (e.g., liFePO ₄ (also abbreviated as LFP)), composite material of lithium iron phosphate and carbon, and manganese lithium phosphate (such as LiMnPO) ₄ ) At least one of a composite material of lithium manganese phosphate and carbon, and a composite material of lithium manganese phosphate and carbon.

In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin.

In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the above components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; and (3) coating the positive electrode slurry on a positive electrode current collector, and obtaining a positive electrode plate after the procedures of drying, cold pressing and the like.

[ negative electrode sheet ]

The negative electrode tab includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material.

As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode active material layer is provided on either one or both of the two surfaces opposing the anode current collector.

In some embodiments, the negative electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may be at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more.

In some embodiments, the anode active material layer further optionally includes a binder. The binder may be at least one selected from the group consisting of Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

In some embodiments, the anode active material layer may further optionally include a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.

In some embodiments, the anode active material layer may also optionally include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like.

In some embodiments, the negative electrode sheet may be prepared by: dispersing the above components for preparing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, and obtaining a negative electrode plate after the procedures of drying, cold pressing and the like.

[ electrolyte ]

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The type of electrolyte is not particularly limited in this application, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorodioxaato phosphate, and lithium tetrafluorooxalato phosphate.

In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methylethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1, 4-butyrolactone, sulfolane, dimethyl sulfone, methyl sulfone, and diethyl sulfone.

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

[ isolation Membrane ]

In some embodiments, a separator is included in the electrode assembly between the positive and negative electrode tabs.

In some embodiments, the battery cell further includes a separator positioned between the positive and negative electrode sheets.

The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability may be used.

In some embodiments, the material of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the battery cell may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the exterior packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, or the like. The outer package of the battery cell may also be a pouch, such as a pouch-type pouch. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

The shape of the battery cell is not particularly limited in this application, and may be cylindrical, square, or any other shape. For example, fig. 1 is a square-structured battery cell 5 as one example.

In some embodiments, referring to fig. 2, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and those skilled in the art may select the number according to specific practical requirements.

In some embodiments, the battery cells may be assembled into a battery module, and the number of battery cells included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

Fig. 3 is a battery module 4 as an example. Referring to fig. 3, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of battery cells 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a housing having an accommodating space in which the plurality of battery cells 5 are accommodated.

In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

Fig. 4 and 5 are battery packs 1 as an example. Referring to fig. 4 and 5, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

In addition, the application also provides an electric device, which comprises at least one of the battery cell, the battery module or the battery pack. The battery cell, the battery module, or the battery pack may be used as a power source of the power device, and may also be used as an energy storage unit of the power device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

As the electricity consumption device, a battery cell, a battery module, or a battery pack may be selected according to the use requirements thereof.

Fig. 6 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. To meet the high power and high energy density requirements of the power device for the battery cells, a battery pack or battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a battery cell can be used as a power supply.

Hereinafter, embodiments of the present application are described. The embodiments described below are exemplary only for the purpose of illustrating the present application and are not to be construed as limiting the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

(1) Hexafluorophosphoric acid(HPF ₆ ) With N, N-dimethylhexylamine (R) ¹ 、R ² Are all methyl, R ³ N-hexyl), then adding lithium carbonate (the mass ratio of the three substances is 2:5:1 in sequence), stirring at 300rpm for reaction for 120min at 45 ℃, filtering a reaction system after the reaction is finished, collecting a solid phase, and drying at 35 ℃ for 120h to obtain a pore-forming agent with the average particle size of 60 mu m, wherein the mass ratio of lithium ions, hexafluorophosphate ions and N, N-dimethylhexylamine is 1:1:4;

(2) Taking 5kg of pore-forming agent prepared in the step (1), 1kg of conductive agent (superconducting carbon+single-walled carbon nano tube, mass ratio of 1:1), 1kg of binder (polyvinylidene fluoride) and 93kg of positive electrode active material (LiNi) _0.96 Co _0.02 Mn _0.02 O ₂ ) Uniformly mixing 5kg of magnetic modification material (ferroferric oxide) and 200L of solvent (N-methylpyrrolidone) to obtain positive electrode slurry, wherein the mass of a pore-forming agent in the slurry is 5% of the total mass of solid components;

(3) Coating the anode slurry prepared in the step (2) on two sides of an aluminum foil with the thickness of 10 mu m, wherein the total thickness after coating is 500 mu m, maintaining the temperature at 100 ℃ in the coating process, decomposing a pore-forming agent to produce gas, and pressing to obtain a 400 mu m thick anode plate substrate with an air passage;

(4) The preparation method comprises the steps of (1) coating a positive electrode plate substrate, a diaphragm and a negative electrode plate (the negative electrode slurry is coated on two sides of a copper foil with the thickness of 4.5 mu m, the total thickness is 125 mu m after coating, and tabletting to obtain a negative electrode plate with the thickness of 110 mu m, wherein the negative electrode slurry is SiO: SP: SWCNT: PAALi=96.8%: 1.04%:0.06%:2.1%, wherein gram capacity is 1250mAh/g after mixing silicon oxide and graphite), and injecting electrolyte (lithium ion concentration is 0.5mol/L, and solvent is dimethyl carbonate), dissolving residual lithium salt in the positive electrode plate substrate by the electrolyte to form a porous positive electrode plate, so as to obtain a soft-package battery, and standing for 24h at 45 ℃;

(5) And (3) standing the battery in the step (4) for 12 hours, then charging to 3.5V with a constant current of 0.02C, discharging to 4.6V with a constant current of 0.1C, charging to 0.02C with a constant voltage of 4.6V, standing for 3min, discharging to 2.5V with a constant current of 0.1C, decompressing, pumping, sealing, and completing the formation of the components.

Example 2

Substantially the same as in example 1, except that the drying temperature was lowered to 25℃for 200 hours and the particle size was 80. Mu.m in step (1).

Example 3

Substantially the same as in example 1, except that the elevated drying temperature in step (1) was 45℃for 200 hours and the particle size was 30. Mu.m.

Example 4

Substantially the same as in example 1, except that the amount of the pore-forming agent in step (2) was adjusted so that the mass of the pore-forming agent in the positive electrode slurry accounted for 1% of the total mass of the solid components.

Example 5

Substantially the same as in example 1, except that the amount of the pore-forming agent in step (2) was adjusted so that the mass of the pore-forming agent in the positive electrode slurry was 10% of the total mass of the solid components.

Example 6

Substantially the same as in example 1, except that N, N-dimethylhexylamine was used in an amount of 20mol in step (1), the resulting pore-forming agent had a particle diameter of 100. Mu.m.

Example 7

Substantially the same as in example 1, except that the total thickness after coating in step (3) was 800 μm, and the positive electrode sheet substrate having a thickness of 600 μm was obtained after pressing.

Example 8

Substantially the same as in example 1, except that the ligand molecule used in step (1) was N, N-dimethylpropylamine (R ¹ 、R ² Are all methyl, R ³ N-propyl).

Example 9

Substantially the same as in example 1, except that the acid used in step (1) was difluorophosphoric acid.

Example 10

Steps (2) to (5) are consistent with example 1, and the pore-forming agent is prepared by adopting a method B in step (1), and the specific steps are as follows:

lithium hexafluorophosphate (LiPF) ₆ ) Dissolving in 1000mLAgent (polycarbonate) and then N, N-dimethylhexylamine (R) ¹ 、R ² Are all methyl, R ³ N-hexyl), the ratio of the lithium hexafluorophosphate to the N, N-dimethylhexylamine substance is 5:1, stirring and reacting for 120min at the temperature of 45 ℃ at the rotating speed of 300rpm, filtering the reaction system after the reaction is finished, collecting a solid phase, and drying for 100h at the temperature of 35 ℃ to obtain the pore-forming agent with the average particle diameter of 70 mu m.

Example 11

Substantially the same as in example 10, except that in step (1), lithium difluorosulfonimide salt (LiSSI) was used in place of lithium hexafluorophosphate (LiPF) ₆ )。

Example 12

Substantially the same as in example 10, except that in step (1), an equal amount of lithium dioxaborate (LiBOB) was used in place of lithium hexafluorophosphate (LiPF) ₆ ) And the positive electrode active material used in step (2) is replaced with 0.5Li [ Li ] in the amount of the same substance _1/3 Mn _2/3 ]O ₂ ·0.5LiNiO ₂ 。

Comparative example 1

Substantially the same as in example 1, except that the drying temperature was lowered to 0℃for 400 hours in step (1), and the particle size was 210. Mu.m.

Comparative example 2

Substantially the same as in example 1, except that the elevated drying temperature in step (1) was 60℃for 40 hours, and the particle size was 8. Mu.m.

Comparative example 3

Substantially the same as in example 1, except that the amount of the pore-forming agent in step (2) was adjusted so that the mass of the pore-forming agent in the positive electrode slurry was 0.1% of the total mass of the solid components.

Comparative example 4

Substantially the same as in example 1, except that the amount of the pore-forming agent in step (2) was adjusted so that the mass of the pore-forming agent in the positive electrode slurry was 15% of the total mass of the solid components.

Comparative example 5

Substantially the same as in example 1, except that N, N-dimethylhexylamine was used in an amount of 1mol in step (1), the resulting pore-forming agent had a particle diameter of 5. Mu.m.

Comparative example 6

Substantially the same as in example 1, except that the total thickness after coating in step (3) was 1200 μm, and the positive electrode sheet substrate having a thickness of 1000 μm was obtained after pressing.

Comparative example 7

Substantially the same as in example 1, except that the total thickness after coating in step (3) was 100 μm, and the positive electrode sheet substrate having a thickness of 60 μm was obtained after pressing.

Comparative example 8

Substantially the same as in example 1, except that the ligand molecule used in step (1) was N, N-dimethyloltert-butylamine (R ¹ 、R ² Are all hydroxymethyl groups, R ³ Tertiary butyl).

Comparative example 9

Substantially the same as in example 1, except that the coating temperature in step (3) was 60 ℃.

Comparative example 10

Substantially the same as in example 1, except that an electrolyte having a lithium ion concentration of 1.2mol/L was used in step (4).

Characterization test:

(1) Energy density testing: the volume of the battery cell is tested, the square shell battery cell can be calculated through the length, width and height, the cylindrical battery cell can be calculated through the height and diameter, and the soft package battery cell can obtain the volume of the battery cell through a drainage method; then charging and discharging are carried out at the temperature of 25 ℃ through a charging and discharging device, the discharging energy is recorded, and the volume energy density of the battery cell is obtained by dividing the discharging energy by the volume of the battery cell.

(2) And (3) testing the cycle performance: the secondary batteries prepared in each example and comparative example were charged to a charge cutoff voltage of 4.25V at a constant current of 1C, then charged at a constant voltage to a current of 0.05C or less, left standing for 5min, and then discharged to a discharge cutoff voltage of 2.5V at a constant current of 1C for 5min, which is a charge-discharge cycle. The battery was subjected to a cyclic charge-discharge test in this way until the battery capacity decayed to 80%. The cycle number at this time is the cycle life of the battery at 25 ℃.

(3) Gram capacity test: the secondary batteries prepared in each example and comparative example were charged to a charge cutoff voltage of 4.25V at a constant current of 0.1C, then charged at a constant voltage to a current of 0.02C or less, left standing for 5min, discharged to a discharge cutoff voltage of 2.5V at a constant current of 0.1C, left standing for 5min, and discharged capacity was obtained, and then gram capacity was calculated according to the active material content.

(4) Quick charge capability test: the batteries of the above examples and comparative examples were charged and discharged for the first time at 25C (i.e., a current value at which the theoretical capacity was completely discharged within 1 h) at a current of 1C, specifically including: the battery is charged to 4.25V with constant current at 1C multiplying power, then charged to current less than or equal to 0.05C with constant voltage, kept stand for 5min, discharged to 2.5V with constant current at 0.33C multiplying power, and the actual capacity is recorded as C0.

And then sequentially charging the battery to a full battery Charge cut-off voltage of 4.25V or a 0V negative cut-off potential (based on the previous achievement) by using 1.0C0, 1.3C0, 1.5C0, 1.8C0, 2.0C0, 2.3C0, 2.5C0, 3.0C0 and constant current, after each charging is completed, discharging to a full battery discharge cut-off voltage of 2.8V by using 1C0, recording the corresponding negative potentials when charging to 10%, 20%, 30%, … … and 80% SOC (State of Charge) under different charging rates, drawing charging rate-negative potential curves under different SOC states, linear fitting to obtain charging rates when the negative potential under different SOC states is 0V, wherein the charging rates are respectively marked as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC and C80% SOC, and calculating the charging rate of the battery from 60/C20% SOC+60/C60+60/C60+60+60/C60% SOC to 10+SOC 60+60+SOC according to the formula (60/C20+60+60+SOC/C60+60+SOC is calculated as the unit of 10+60+SOC). The shorter the time, the more excellent the quick charge performance of the battery.

TABLE 1

As can be seen from Table 1, when the pore-forming agent prepared in each embodiment of the application is used for preparing a thicker electrode, the pore-forming agent can effectively improve the porosity of the electrode, improve the wettability of a pole piece, effectively accelerate ion transmission, reduce liquid phase polarization and increase gram capacity exertion of an electrode material, thereby improving the cycle performance, gram capacity and quick charge capacity of a lithium battery.

Comparative example 1 the pore former had an excessively large particle diameter compared to example 1, resulting in a decrease in energy density, gram capacity and cycle performance; in the comparative example 2, the pore-forming agent has too small particle size, and the pore-closing phenomenon can occur after rolling, so that the characteristic thickness of the electrode is reduced, the gram capacity is exerted poorly, and the quick charge performance is also reduced; in comparative example 3, the pore-forming agent was used in an excessively small amount, resulting in serious deterioration of the cycle performance; in comparative example 4, too much pore-forming agent was used, resulting in a significant decrease in energy density and cycle performance; in comparative example 5, the ligand molecule is used too little, which results in that part of lithium salt is not coordinated, the particle size is smaller, the pore closing phenomenon can be caused after rolling, the characteristic thickness of the electrode is reduced, the gram capacity is exerted poorly, and the quick charge performance is also reduced; in comparative examples 6 to 7, the ratio of pore-forming agent particle diameter to electrode thickness was not proper, which also resulted in a decrease in energy density and cycle performance; in comparative example 8, the ligand molecules have excessive steric hindrance, part of the ligand molecules cannot coordinate, the particle size of the formed pore-forming agent is smaller, and the pore-forming agent is unevenly distributed, so that the performance of the battery is seriously affected; in comparative example 9, the coating temperature was too low, the ligand molecules were not completely decomposed, remained in the electrode sheet, and the cycle performance of the battery was seriously affected; in comparative example 10, too high concentration of lithium ions in the electrolyte can cause too much lithium to be precipitated on the pole piece under the condition that the pore-forming agent itself contains lithium, so that the pH of the pole piece is too high and water is easily absorbed, thereby affecting the electrical performance of the battery.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the patent. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.

Claims

A pore-forming agent comprising a central ion, an acid radical ion and a ligand molecule, wherein the central ion is lithium ion, and the ligand molecule has a structure shown in formula I:

wherein R is ¹ 、R ² Each independently selected from methyl or ethyl, R ³ Independently selected from alkyl groups having 1 to 11 carbon atoms.
A pore former according to claim 1, wherein the acid ion is a monovalent anion.
A pore former according to any one of claims 1 to 2, wherein the acid ion comprises PF ₆ ^- 、BOB ^- 、ODFB ^- 、TFSI ^- 、FSI ^- 、TNFSI ^- 、PO ₂ F ₂ ^- One or more of the following.
A pore former according to any one of claims 1 to 3, wherein R ³ Independent and independentIs selected from alkyl groups having 1 to 6 carbon atoms.
A pore former according to any one of claims 1 to 4, wherein R ¹ 、R ² Methyl, said R is ³ Selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl.
A pore former according to any one of claims 1 to 5, wherein R ¹ 、R ² Methyl, said R is ³ Is n-hexyl.
A pore former according to any one of claims 1 to 6, having an average particle size in the range of 10 μm to 200 μm.
A pore former according to any one of claims 1 to 7, wherein the ratio of the amounts of the species of the central ion, acid ion and ligand molecule in the pore former is 1:1 (1 to 4).
A positive electrode slurry comprising a positive electrode active material, an auxiliary agent, a solvent, and the pore-forming agent according to any one of claims 1 to 8.
The positive electrode slurry according to claim 9, wherein the mass percentage of the pore-forming agent in the solid component is 1 to 10%.
The positive electrode slurry according to any one of claims 9 to 10, wherein the mass percentage of the pore-forming agent in the solid component in the positive electrode slurry is 2 to 5%.
The positive electrode slurry according to any one of claims 9 to 11, characterized in that the positive electrode active material comprises Li _a Ni _x Co _y Mn _z M ¹ _(1-x-y-z) O ₂ 、vLi[Li _1/3 Mn _2/3 ]O ₂ ·(1–v)LiM ² O ₂ Or Li (lithium) _1-w CoO ₂ One or more of the following;

wherein a is more than or equal to 0.9 and less than or equal to 1.2,0.5, x is more than or equal to 0.98,0 and y is more than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.2, M ¹ Each occurrence is independently selected from Al, mg, zn, zr, ti or Fe;

0≤v≤1，M ² each occurrence is independently selected from Ni, co or Mn;

0≤w≤0.5。
the positive electrode slurry according to any one of claims 9 to 12, wherein the auxiliary agent comprises one or more of a magnetic finishing material, a thickener, a conductive agent, a binder, and a dispersant.
The positive electrode slurry according to any one of claims 9 to 13, wherein the viscosity of the positive electrode slurry is 6000 mPa-s to 15000 mPa-s at 25±0.5 ℃.
The positive electrode slurry according to any one of claims 9 to 14, wherein the solid content of the positive electrode slurry is 68% to 76%.
A positive electrode sheet substrate, characterized by comprising a positive electrode current collector and a positive electrode active material layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer is formed by solidifying the positive electrode slurry according to any one of claims 9 to 15.
The positive electrode tab substrate according to claim 16, wherein the positive electrode active material layer has a thickness of 120 μm to 400 μm.
The positive electrode tab substrate according to any one of claims 16 to 17, wherein the ratio of the average particle diameter of the pore-forming agent to the thickness of the positive electrode active material layer is in the range of 1 (5 to 7).
An electrode assembly comprising a stacked arrangement of a negative electrode sheet, a separator, and the positive electrode sheet substrate of any one of claims 16-18, the separator being disposed between the negative electrode sheet and the positive electrode sheet substrate.
The battery cell is characterized by comprising a negative electrode plate, an isolating film and a positive electrode plate which are distributed in a laminated way, wherein the isolating film is arranged between the negative electrode plate and the positive electrode plate;

the positive electrode plate is prepared by the contact treatment of the positive electrode plate substrate and electrolyte according to any one of claims 16 to 18, and the positive electrode plate has a porous structure.
The battery cell of claim 20, wherein the concentration of lithium ions in the electrolyte is 0mol/L to 1mol/L, and the solvent of the electrolyte comprises one or more of dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and polycarbonate.
The battery cell of any one of claims 20-21, wherein the positive electrode sheet has a porosity of 25-40%.
The battery cell according to any one of claims 20 to 22, wherein the pore size of the positive electrode sheet is 60 μm to 200 μm.
The battery cell of any one of claims 20-23, wherein the positive electrode sheet has a compacted density of 2.9g/cm ³ ～3.5g/cm ³ 。
A battery module comprising the battery cell of any one of claims 20 to 24.
A battery pack comprising the battery module of claim 25.
An electrical device comprising one or more of the battery cell of any one of claims 20-24, the battery module of claim 25, and the battery pack of claim 26.
The method for producing a pore-forming agent according to any one of claims 1 to 8, comprising the steps of method a or method B:

the method A comprises the following steps:

mixing acid with the ligand molecules to prepare a mixture, reacting the mixture with lithium carbonate, performing solid-liquid separation after the reaction is finished, collecting a solid phase, and drying;

The method B comprises the following steps:

dissolving lithium salt in a solvent to prepare a lithium salt solution, reacting the lithium salt solution with the ligand molecules, performing solid-liquid separation after the reaction is finished, collecting a solid phase, and drying.
A method of preparing a pore former according to claim 28, wherein the acid comprises one or more of hexafluorophosphoric acid and difluorophosphoric acid; the lithium salt comprises LiPF ₆ 、LiBOB、LiODFB、LiTFSI、LiFSI、LiTNFSI、LiPO ₂ F ₂ The solvent includes one or more of dimethyl carbonate, diethyl carbonate, polycarbonate, and fluoroethylene carbonate.
A method of preparing a pore former according to any one of claims 28 to 29, wherein in method a the ratio of the amount of acid to the amount of ligand molecular species is 1 (1) to (10).
A method of preparing a pore former according to any one of claims 28 to 30, wherein in method a the ratio of the amount of acid to the amount of material of the lithium carbonate is 2 (0.8 to 1.2).
A method of preparing a pore former according to any one of claims 28 to 29, wherein in method B the ratio of the amount of lithium salt to the amount of substance of the ligand molecule is 1 (2 to 5).
The method of producing a pore-forming agent according to any one of claims 28 to 29 and 32, wherein in the method B, the lithium ion concentration in the lithium salt solution is 0.5mol/L to 1mol/L.
The method for preparing a positive electrode sheet substrate according to any one of claims 16 to 18, comprising the steps of:

coating the positive electrode slurry according to any one of claims 9 to 15 on at least one surface of a positive electrode current collector, drying, and pressing.
The method of claim 34, wherein the positive electrode slurry has a coating thickness of 250 μm to 800 μm.
The method of any one of claims 34 to 35, wherein the temperature at which the positive electrode slurry is applied is 80 ℃ to 120 ℃.
The method for producing a battery cell according to any one of claims 20 to 24, comprising the steps of: the electrolyte is injected into a battery case equipped with the electrode assembly of claim 16.