CN117133882A

CN117133882A - Negative electrode plate, processing method thereof, battery and electronic equipment

Info

Publication number: CN117133882A
Application number: CN202310268791.5A
Authority: CN
Inventors: 禹智昊; 吴霞; 朱华
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2023-03-10
Filing date: 2023-03-10
Publication date: 2023-11-28

Abstract

The application provides a negative pole piece, a processing method thereof, a battery and electronic equipment, and relates to the technical field of terminals. The negative electrode sheet includes: a negative electrode current collector and a negative electrode polar material layer. The negative electrode polar material layer is arranged on the surface of the negative electrode current collector, the negative electrode polar material layer comprises active material particles, the active material particles comprise a core and a flexible coating layer, the core is wrapped by the flexible coating layer, the core is made of silicon-based material particles, and the flexible coating layer is made of supermolecular polymer. In the charge and discharge process of the battery, the flexible coating layer can generate a certain constraint effect on the volume expansion of the inner core, and release the internal stress generated by the volume change of the inner core to a certain extent, so that the risk of the expansion and rupture of the inner core is reduced to a certain extent, and the problems of the super-thick battery core and the rapid capacity attenuation caused by the increase of the porosity of the anode polar material layer and the loss of active material particles are prevented.

Description

Negative electrode plate, processing method thereof, battery and electronic equipment

Technical Field

The application relates to the technical field of terminals, in particular to a negative electrode plate, a processing method thereof, a battery and electronic equipment.

Background

With the development of economy, electronic devices such as portable electronic products, unmanned aerial vehicles, electric vehicles, and the like are now urgently required to have higher energy density, higher power density, longer cycle life, and safer batteries. However, the energy density of the existing lithium battery using graphite as the negative electrode is close to the upper limit, and the requirements of users on the endurance and standby of the electronic equipment cannot be met.

Silicon-based materials are active materials with much higher gram capacity than graphite. The silicon-based material has the advantages of higher volume specific capacity, moderate lithium intercalation and deintercalation potential, abundant reserves, low price, environmental protection, no toxicity and the like. Therefore, silicon-based materials are ideal choices for improving the energy density of lithium batteries by being used as a battery negative electrode active material instead of graphite materials.

However, since silicon-based materials have a large volume effect, the rate of change of volume due to expansion/contraction thereof is large in the process of repeatedly extracting lithium (i.e., charge and discharge). Therefore, in the process of charging and discharging the battery, internal stress accumulation of silicon-based material particles is easily caused, and finally, the silicon-based material particles are expanded, ruptured and pulverized, and simultaneously, SEI films are damaged, so that the ruptured silicon-based material particles are contacted with electrolyte, and therefore, new SEI films can be regenerated at the damaged positions of the SEI films, and lithium ions in the electrolyte are consumed. In addition, the expansion and rupture of the silicon-based material particles also damages the conductive network of the negative electrode, so that part of active substances cannot participate in the reaction, and capacity loss is caused. Meanwhile, due to the volume deformation of the silicon-based material, the negative electrode polar material layer generates and accumulates larger stress, so that the negative electrode polar material layer is broken, further, electric contact between silicon-based material particles and between the silicon-based material particles and a current collector is lost, even part of the negative electrode polar material layer falls off from the current collector, and the internal resistance and capacity loss of the battery are caused.

Disclosure of Invention

The embodiment of the application provides a negative electrode plate, a processing method thereof, a battery and electronic equipment.

In order to achieve the above purpose, the embodiment of the present application adopts the following technical scheme:

in a first aspect, there is provided a negative electrode tab comprising: a negative electrode current collector and a negative electrode polar material layer. The negative electrode polar material layer is arranged on the surface of the negative electrode current collector, the negative electrode polar material layer comprises active material particles, the active material particles comprise a core and a flexible coating layer, the core is wrapped by the flexible coating layer, the core is made of silicon-based material particles, and the flexible coating layer is made of supermolecular polymer.

Since supramolecular polymers are a class of polymers that are linked by non-covalent bonds. The interaction of the non-covalent bonds is reversible, i.e., the non-covalent bonds in the supramolecular polymer can be broken and formed continuously. Therefore, the supermolecular polymer can respond to a certain external stimulus, and the stimulus is withdrawn to restore the initial state. Because the flexible coating coats the silicon-based material particles, when the volume of the silicon-based material particles is increased in the charging and discharging process, non-covalent bonds in the supramolecular polymer are continuously broken and regenerated, so that the flexible coating can adapt to the volume change of the silicon-based material particles and continuously generate tensile deformation. When the volume of the silicon-based material particles becomes smaller, non-covalent bonds in the supramolecular polymer are continuously broken and regenerated, so that the flexible coating layer can adapt to the volume change of the silicon-based material particles and continuously generate shrinkage deformation. Therefore, the flexible coating layer has excellent elastic deformability. In addition, the supermolecular polymer also has certain adhesive property, so that the flexible coating layer has certain adhesive capability.

In this way, in the charge and discharge process of the battery, the flexible coating layer can generate a certain constraint effect on the volume expansion of the inner core, and release the internal stress generated by the volume change of the inner core to a certain extent, so that the risk of the expansion and rupture of the inner core is reduced to a certain extent, and the risk of the damage of the conductive network of the negative electrode is reduced. And the flexible coating layer can also play a role in isolating the inner core and the electrolyte, so that the problem of regeneration caused by SEI film rupture is avoided, the consumption of lithium ions is avoided, and the capacity and the service life of the battery are improved. In addition, the problem of large stress accumulation at the position of the negative electrode polar material layer caused by the volume change of the inner core can be prevented to a certain extent, so that the breakage of the negative electrode polar material layer is avoided, the problem that electrical contact between silicon-based material particles and between the silicon-based material particles and the negative electrode current collector is lost, and the problem that part of the negative electrode polar material layer falls off from the negative electrode current collector is avoided, and the capacity and the service life of the battery are improved. In addition, because the supermolecular polymer has certain adhesive property, in the anode polar material layer, the adjacent two active material particles and the conductive additive are favorable for being adhered by virtue of the flexible coating layer, so that the structural strength of the anode polar material layer is improved, and the bonding strength between the anode polar material layer and the anode current collector is also favorable for being improved, thereby further preventing part of the anode polar material layer from falling off from the anode current collector, and further solving the problems of increased internal resistance and capacity loss of the battery.

In some embodiments of the first aspect, the silicon-based material particles comprise at least one of silicon particles, silica particles, silicon oxide particles, silicon carbon composite particles. That is, the silicon-based material particles include one or more of silicon particles, silicon dioxide particles, silicon oxide particles, silicon carbon composite particles.

In some embodiments of the first aspect, the flexible coating is adhered to the outer surface of the inner core. Therefore, the structure is simple, and the processing and the manufacturing are convenient.

In some embodiments of the first aspect, the hydrogen-bonded supramolecular polymers have excellent reversibility, so that the supramolecular polymers have the advantages of good film forming property, strong elastic deformation capability and ductility. In addition, the hydrogen bond type supermolecular polymer has better adhesive property. Thus, the supramolecular polymer is a hydrogen-bonding supramolecular polymer.

In some embodiments of the first aspect, the flexible coating is formed from a supramolecular polymer. Therefore, the material has simple components, is convenient to manufacture, is beneficial to reducing the cost, and is beneficial to improving the elastic deformation capability and the bonding performance of the flexible coating layer.

In some embodiments of the first aspect, the flexible coating may further comprise a conductive material. For example, the flexible coating is formed by mixing a supramolecular polymer and a conductive material. Therefore, the flexible coating layer can be used for conducting electricity conveniently, so that a conducting network is formed between the inner core and the conducting additive conveniently, and the charge and discharge efficiency of the battery is improved.

Illustratively, the conductive material includes one or two or more of conductive carbon black, graphene, carbon nanotubes, graphite.

In some embodiments of the first aspect, the peel strength of the flexible coating layer has a value in the range of greater than or equal to 10N/m. Therefore, the bonding strength between the flexible coating layer and the inner core is high, so that the bonding strength between the active material particles and the negative electrode current collector is improved, and the situation that part of the negative electrode polar material layer is peeled off from the negative electrode current collector and enters the electrolyte in the charge-discharge process of the battery can be effectively avoided. Furthermore, the problems of increased internal resistance and capacity loss of the battery caused by losing electrical contact among silicon-based material particles, between the silicon-based material particles and the negative current collector and even falling of part of the negative electrode polar material layer from the negative current collector due to cracking and peeling of part of the negative electrode polar material layer can be avoided, and the capacity and the service life of the battery are improved.

Illustratively, the peel strength of the flexible cover layer has a range of values less than or equal to 20N/m.

In some embodiments of the first aspect, the flexible coating layer has a value of the elastic modulus in the range of 0.3GPa to 8GPa. Thus, the flexible coating layer has better elastic deformation capability.

Illustratively, the flexible coating layer has a value of elastic modulus: 0.5GPa, 0.6GPa, 0.8GPa, 0.9GPa, 1GPa, 1.2GPa, 1.5GPa, 1.7GPa, 1.8GPa, 2GPa, 2.1GPa, 2.5GPa, 2.8GPa, 3GPa, 3.2GPa, 3.5GPa, 3.8GPa, 4GPa, 4.2GPa, 4.5GPa, 4.8GPa, 5.2GPa, 5.5GPa, 5.8GPa, 6GPa, 6.2GPa, 6.5GPa, 6.7GPa, 7.2GPa, 7.5GPa, or 7.8GPa. Thereby, the elastic deformability of the flexible coating layer is ensured.

In some embodiments of the first aspect, the material forming the supramolecular polymer comprises a first material and a second material. The first material comprises a polyacid and/or a polyanhydride, the polyanhydride being formed by dehydration of the polyacid; wherein the polyacid comprises one or more of monomeric fatty acid, dimeric fatty acid and trimeric fatty acid. The second material comprises a polyol and/or a polyamine. The supermolecular polymer formed by the first material and the second material has good elastic deformation capability and bonding performance, and the material has low price and low cost.

Exemplary polyamines include, but are not limited to, at least one of diethylenetriamine, triethylenetetramine, ethylenediamine, propyltriamine, and the like.

Exemplary polyols include, but are not limited to, at least one of ethylene glycol, glycerol, and the like.

In some embodiments of the first aspect, the weight parts of the first material range from 2 parts to 10 parts when the weight parts of the second material are 1 part. Therefore, the proportion of the first material and the second material is reasonable, and the supermolecular polymer with excellent elastic deformation capability and bonding performance is obtained.

Illustratively, the weight portion of the first material ranges from 4 parts to 8 parts when the weight portion of the second material is 1 part. Therefore, the proportion of the first material and the second material is more reasonable, and the supermolecular polymer with excellent elastic deformation capability and bonding performance is obtained.

In some embodiments of the first aspect, the negative electrode polar material layer further comprises a conductive additive, the negative electrode polar material layer being composed of the conductive additive and the active material particles. Thereby, the material cost is reduced.

Specifically, the conductive additive includes at least one form of additive selected from the group consisting of a particulate additive, a linear additive and a plate-like additive.

In some embodiments of the first aspect, the conductive additive comprises both particulate and linear additives; alternatively, the conductive additive includes both forms of additives, particulate additives and platelet additives; alternatively, the conductive additive includes additives in two forms, namely a linear additive and a plate-like additive; alternatively, the conductive additive includes three types of additives, namely, a particulate additive, a linear additive and a plate additive. In this way, the conductive additives with different forms can be mutually filled, the contact area between the conductive additives is increased, and the distribution density of the conductive additives in the anode polar material layer is improved, so that the conductive additives with different forms can be utilized to construct a conductive network in the anode polar material layer, and a conductive path is formed. And the conductive additives in different forms are mutually filled to increase the contact area, so that the conductive capability of the anode polar material layer is ensured on the premise of lower doping amount of the conductive additives. And the degree of mutual embedding of the conductive additive with different forms and the flexible coating layer is different, and the conductive additive with different forms is favorable for making up the problem that a conductive path cannot be formed with the inner core due to weak embedding ability of the conductive additive with a single form and the flexible coating layer, and is more favorable for constructing the conductive path between the inner core in the active material particles and the conductive additive.

In some embodiments of the first aspect, the linear additive comprises carbon nanotubes and/or carbon fibers; the platelet additive comprises platelet graphene and/or platelet graphite; the particulate additive includes carbon black and/or graphite.

In some embodiments of the first aspect, the ratio of the equivalent diameter of the active material particles to the equivalent diameter of the inner core is greater than 1 and less than or equal to 1.3. Thereby be favorable to limiting the thickness of flexible coating layer in reasonable within range, on the one hand be favorable to guaranteeing flexible coating layer's elastic deformation ability and adhesive property, on the other hand be favorable to guaranteeing flexible coating layer's structural strength.

In some embodiments of the first aspect, the equivalent diameter of the inner core is on the order of nanometers. Therefore, compared with a large-size inner core, the volume effect of the inner core in the battery charging and discharging process is reduced, more active material particles are uniformly distributed in the negative electrode polar material layer, and the battery charging and discharging efficiency is improved.

In some embodiments of the first aspect, the equivalent diameter of the inner core is on the order of microns. That is, the equivalent diameter of the core is greater than or equal to 1 micrometer (um) and less than 1000um. Thus, the flexible coating layer is more beneficial to forming on the inner core, and the bonding strength between the flexible coating layer and the inner core is improved.

In some embodiments of the first aspect, the equivalent diameter of the inner core has a value in the range of 10nm to 30um. In this way, on the one hand, the problem that the formation of the flexible coating layer on the surface of the inner core is unfavorable because the equivalent diameter of the inner core is too small is advantageously prevented, and the bonding strength between the flexible coating layer and the inner core is weak, and on the other hand, the problem that the volume change of the inner core in the charge and discharge process is too large because the size of the inner core is too large is advantageously prevented. That is, the equivalent diameter of the inner core is 10 nm-30 um, so that the size design of the inner core is more reasonable, the connection strength between the flexible coating layer and the inner core can be ensured, the volume change of the inner core in the battery charging and discharging process can be weakened, more active material particles are uniformly distributed in the negative electrode polar material layer, and the battery charging and discharging efficiency is improved.

In a second aspect, the present application provides a battery comprising: positive pole piece, diaphragm and negative pole piece; the negative electrode plate is in any technical scheme, and the positive electrode plate and the negative electrode plate are separated by a diaphragm.

In a third aspect, the present application provides an electronic device comprising: an electric device and a battery, the battery being the battery in the above embodiment. The battery is electrically connected to the electric device.

The technical effects caused by any one of the design manners of the second aspect to the third aspect may be referred to the technical effects caused by the different design manners of the first aspect, and will not be described herein.

In a fourth aspect, the present application provides a method for processing a negative electrode sheet, the method comprising: a negative electrode polar material layer is arranged on the surface of the negative electrode current collector; the anode polar material layer comprises active material particles, the active material particles comprise an inner core and a flexible coating layer, the inner core is wrapped by the flexible coating layer, the inner core comprises silicon-based material particles, and the flexible coating layer comprises a supermolecular polymer.

The flexible coating layer can generate a certain constraint effect on the volume expansion of the core in the charge and discharge process of the battery, and release the internal stress generated by the volume change of the core to a certain extent, so that the risk of the expansion and rupture of the core is reduced to a certain extent, and the risk of the damage of the conductive network of the negative electrode is further reduced. And the flexible coating layer can also play a role in isolating the inner core and the electrolyte, so that the problem of regeneration caused by SEI film rupture is avoided, the consumption of lithium ions is avoided, and the capacity and the service life of the battery are improved. In addition, the problem of large stress accumulation at the position of the negative electrode polar material layer caused by the volume change of the inner core can be prevented to a certain extent, so that the breakage of the negative electrode polar material layer is avoided, the problem that electrical contact between silicon-based material particles and between the silicon-based material particles and the negative electrode current collector is lost, and the problem that part of the negative electrode polar material layer falls off from the negative electrode current collector is avoided, and the capacity and the service life of the battery are improved. In addition, because the supermolecular polymer has certain adhesive property, in the anode polar material layer, the adjacent two active material particles and the conductive additive are favorable for being adhered by virtue of the flexible coating layer, so that the structural strength of the anode polar material layer is improved, and the bonding strength between the anode polar material layer and the anode current collector is also favorable for being improved, thereby further preventing part of the anode polar material layer from falling off from the anode current collector, and further solving the problems of increased internal resistance and capacity loss of the battery.

In some embodiments of the fourth aspect, because the hydrogen-bonded supramolecular polymers have excellent reversibility, such supramolecular polymers have the advantage of good film forming properties, elastic deformability and ductility. In addition, the hydrogen bond type supermolecular polymer has better adhesive property. Thus, the supramolecular polymer is a hydrogen-bonding supramolecular polymer.

In some embodiments of the fourth aspect, providing a negative electrode polar material layer on a surface of a negative electrode current collector includes: heating the first material and the second material in a protective gas atmosphere to enable the first material and the second material to react so as to obtain a supermolecular polymer slurry; disposing a supramolecular polymer slurry on an outer surface of an inner core to form active material particles having a flexible coating layer; thoroughly mixing the active material particles and the conductive additive to obtain a polar slurry; the polar paste is disposed on the surface of the negative electrode current collector to obtain a negative electrode polar material layer. Thus, the flexible coating layer is formed of only a supramolecular polymer, i.e. the flexible coating layer is formed of a single supramolecular polymer material. Therefore, the material has simple components, is convenient to manufacture, is beneficial to reducing the cost, and is beneficial to improving the elastic deformation capability and the bonding performance of the flexible coating layer. And the negative electrode polar material layer is formed by the conductive additive and the active material particles, so that the setting of an adhesive is saved, and the material cost is reduced. In addition, the negative electrode polar material layer can be tightly attached to the negative electrode current collector, so that the bonding strength of the negative electrode polar material layer and the negative electrode current collector can be improved. The method is simple, the conditions are easy to control, and the method is suitable for industrial production.

In some embodiments of the fourth aspect, providing a negative electrode polar material layer on a surface of a negative electrode current collector includes: heating the first material and the second material in a protective gas atmosphere to enable the first material and the second material to react so as to obtain a supermolecular polymer slurry; disposing a supramolecular polymer slurry on a surface of an inner core to form active material particles having a flexible coating layer; thoroughly mixing the active material particles, the conductive additive and the solvent to obtain a polar slurry; the polar slurry is arranged on the surface of the negative electrode current collector; and drying the polar slurry on the negative electrode current collector to volatilize the solvent in the polar slurry so as to obtain a negative electrode polar material layer. Thus, the flexible coating layer is formed of only a supramolecular polymer, i.e. the flexible coating layer is formed of a single supramolecular polymer material. Therefore, the material has simple components, is convenient to manufacture, is beneficial to reducing the cost, and is beneficial to improving the elastic deformation capability and the bonding performance of the flexible coating layer. And the negative electrode polar material layer is formed by the conductive additive and the active material particles, so that the setting of an adhesive is saved, and the material cost is reduced. In addition, the negative electrode polar material layer can be tightly attached to the negative electrode current collector, so that the bonding strength of the negative electrode polar material layer and the negative electrode current collector can be improved. The method is simple, the conditions are easy to control, and the method is suitable for industrial production.

In some embodiments of the fourth aspect, the solvent comprises at least one of water, ethanol, and NMP (N-Methylpyrrolidone).

In some embodiments of the fourth aspect, the first material comprises a polyacid and/or a polyanhydride, the polyanhydride being formed by dehydration of the polyacid; wherein the polyacid comprises one or more of monomeric fatty acid, dimeric fatty acid and trimeric fatty acid. The second material comprises a polyol and/or a polyamine. The supermolecular polymer formed by the first material and the second material has good elastic deformation capability and bonding performance, and the material has low price and low cost.

In some embodiments of the fourth aspect, the peel strength of the flexible coating layer has a range of values greater than or equal to 10N/m. Therefore, the bonding strength between the flexible coating layer and the inner core is high, so that the bonding strength between the active material particles and the negative electrode current collector is improved, and the situation that part of the negative electrode polar material layer is peeled off from the negative electrode current collector and enters the electrolyte in the charge-discharge process of the battery can be effectively avoided. Furthermore, the problems of increased internal resistance and capacity loss of the battery caused by losing electrical contact among silicon-based material particles, between the silicon-based material particles and the negative current collector and even falling of part of the negative electrode polar material layer from the negative current collector due to cracking and peeling of part of the negative electrode polar material layer can be avoided, and the capacity and the service life of the battery are improved.

In some embodiments of the fourth aspect, the flexible coating layer has an elastic modulus ranging from 0.3GPa to 8GPa. Thus, the flexible coating layer has better elastic deformation capability.

In some embodiments of the fourth aspect, disposing a supramolecular polymer slurry on a surface of an inner core to form active material particles having a flexible coating layer, comprising: setting the supermolecular polymer slurry on the surface of the inner core to cover the supermolecular polymer slurry on the surface of the inner core; heating the supramolecular polymer slurry on the surface of the inner core for a second preset time at a second preset temperature; the supramolecular polymer slurry is cooled to form a flexible coating layer. Because the inner core comprises silicon-based material particles, the surfaces of the silicon-based material particles are provided with silicon-oxygen bonds, and the supermolecular polymer slurry on the surface of the inner core is heated, on one hand, the mobility and the diffusivity of the supermolecular polymer slurry are improved, so that the infiltration effect between the supermolecular polymer slurry and the surface of the inner core is improved, and on the other hand, the bonding of non-covalent bonds in the supermolecular polymer and the silicon-oxygen bonds after fracture is improved, so that the bonding strength between the flexible coating layer and the inner core is improved through the two aspects.

In some embodiments of the fourth aspect, the second preset temperature has a value ranging from 70 ℃ to 120 ℃; and/or the value range of the second preset time is 3-100 min. Thus, the non-covalent bond in the supramolecular polymer is beneficial to ensure bonding with the silicon oxygen bond after fracture.

In some embodiments of the fourth aspect, the second predetermined temperature has a value in the range of 90 ℃ to 110 ℃. Thus, the non-covalent bond in the supramolecular polymer is beneficial to ensure bonding with the silicon oxygen bond after fracture.

In some embodiments of the fourth aspect, the second preset time has a value ranging from 3min to 10min. Thus, the non-covalent bond in the supramolecular polymer is beneficial to ensure bonding with the silicon oxygen bond after fracture.

In some embodiments of the fourth aspect, disposing a supramolecular polymer slurry on a surface of an inner core to cover the supramolecular polymer slurry on the surface of the inner core, comprising: setting the supermolecular polymer slurry on the surface of the inner core at a third preset temperature so as to cover the supermolecular polymer slurry on the surface of the inner core; wherein the third preset temperature is greater than room temperature and less than the second preset temperature. The supramolecular polymer slurry is cooled. Therefore, the supramolecular polymer slurry is arranged on the surface of the inner core at the third preset temperature, so that the fluidity and the diffusivity of the supramolecular polymer slurry are improved, the infiltration effect between the supramolecular polymer slurry and the surface of the inner core is improved, and the bonding strength between the coating layer and the inner core is improved.

The third preset temperature is exemplified by a value ranging from 40 ℃ to 50 ℃.

In some embodiments of the fourth aspect, the weight parts of the second material range from 2 parts to 10 parts when the weight parts of the second material are 1 part. Thus, a supramolecular polymer excellent in both elastic deformability and adhesive properties can be advantageously obtained.

In some embodiments of the fourth aspect, the weight parts of the second material range from 4 parts to 8 parts when the weight parts of the second material are 1 part. Thus, a supramolecular polymer excellent in both elastic deformability and adhesive properties can be advantageously obtained.

In some embodiments of the fourth aspect, the conductive additive comprises both particulate additives and linear additives; alternatively, the conductive additive includes both forms of additives, particulate additives and platelet additives; alternatively, the conductive additive includes additives in two forms, namely a linear additive and a plate-like additive; alternatively, the conductive additive includes three types of additives, namely, a particulate additive, a linear additive and a plate additive. In this way, the conductive additives with different forms can be mutually filled, the contact area between the conductive additives is increased, and the distribution density of the conductive additives in the anode polar material layer is improved, so that the conductive additives with different forms can be utilized to construct a conductive network in the anode polar material layer, and a conductive path is formed. And the conductive additives in different forms are mutually filled to increase the contact area, so that the conductive capability of the anode polar material layer is ensured on the premise of lower doping amount of the conductive additives. And the degree of mutual embedding of the conductive additive with different forms and the flexible coating layer is different, and the conductive additive with different forms is favorable for making up the problem that a conductive path cannot be formed with the inner core due to weak embedding ability of the conductive additive with a single form and the flexible coating layer, and is more favorable for constructing the conductive path between the inner core in the active material particles and the conductive additive.

Drawings

Fig. 1 is a diagram of various structural forms of an electronic device according to some embodiments of the present application;

fig. 2 is a front view of a battery provided in some embodiments of the application;

FIG. 3 is a schematic cross-sectional view of the battery shown in FIG. 2 at line A-A;

fig. 4 is a schematic cross-sectional structure of a positive electrode tab in the battery according to fig. 3;

fig. 5 is a schematic cross-sectional structure of a negative electrode tab in the battery according to fig. 3;

fig. 6 is a schematic view of another negative electrode tab according to an embodiment of the present application;

fig. 7 is a schematic view showing a volume change of active material particles in the negative electrode tab according to fig. 6 during charge and discharge;

fig. 8 is a flowchart of a processing method of a negative electrode piece provided by an embodiment of the present application;

FIG. 9 is a flowchart showing a step S10 in the method for manufacturing the negative electrode sheet shown in FIG. 8;

fig. 10 is a specific flowchart of step S12 in the processing method of the negative electrode tab shown in fig. 9;

fig. 11 is a specific flowchart of step S121 in the processing method of the negative electrode tab shown in fig. 10;

fig. 12 is another specific flowchart of step S10 in the processing method of the negative electrode tab shown in fig. 8.

Detailed Description

In embodiments of the present application, the terms "exemplary" or "such as" and the like are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g." in an embodiment should not be taken as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

In embodiments of the present application, 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 implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

In the description of embodiments of the application, the term "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b, or c may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or plural.

In the description of embodiments of the present application, the term "and/or" refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term "and/or" is an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, and may mean: a exists alone, A and B exist together, and B exists alone. In the present application, the character "/" generally indicates that the front and rear related objects are an or relationship.

In the description of embodiments of the present application, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and for example, "connected" may be either detachably connected or non-detachably connected; may be directly connected or indirectly connected through an intermediate medium.

In the description of embodiments of the present application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Before describing the embodiments of the present application, first, a description will be given of a lithium battery and some terms of art to which the embodiments of the present application will be referred, specifically:

working principle of lithium battery: the charging and discharging process of the lithium battery is a process that lithium ions move between the positive pole piece and the negative pole piece. Specifically, during charging of the battery, lithium atoms (Li) of the positive electrode (i.e., hereinafter positive electrode tab) are decomposed into lithium ions (Li) ⁺ ) And electrons (e) ^- ). Electronic (e) ^- ) Through an external circuit to the negative electrode (i.e., the negative electrode tab hereinafter). Lithium ion (Li) ⁺ ) Then it emerges from the lattice of the positive electrode and passes through the electrolyte, through the separator, and to the negative electrode. Lithium ion (Li) ⁺ ) At the negative electrode and the electron (e ^- ) Lithium atoms (Li) are formed. The discharge process of lithium battery is opposite to the charge process, lithium atoms (Li) on the negative electrode lose electrons (e ^- ) Formation of lithium ion (Li) ⁺ ). The electrons pass through an external circuit to the anode. Lithium ion (Li) ⁺ ) Is extracted from the lattice of the negative electrode and passes through the separator to the positive electrode via the electrolyte, lithium ions (Li ⁺ ) In the positive electrode and the electron (e) ^- ) Forming lithium atoms.

Solid electrolyte interface (solid electrolyte interface, SEI) film: is a passivation film having solid electrolyte properties. Specifically, in the first charge and discharge process of the lithium battery, the electrode material reacts with the electrolyte on the solid-liquid phase interface to form a passivation film covering the surface of the electrode material. The passivation film is an excellent conductor of lithium ions and can allow the lithium ions to be transported therein and freely intercalated and deintercalated. It is worth noting that, the formation of the SEI film consumes a part of lithium ions, so that the first charge-discharge irreversible capacity increases. The SEI film has an organic solvent insolubility, can exist stably in an organic electrolyte solution, and solvent molecules cannot pass through the passivation film layer, thereby effectively preventing co-intercalation of the solvent molecules.

Gram volume: the ratio of the capacity that can be released by the active material inside the battery to the mass of the active material.

Specific capacity: specific capacity is divided into two types, one is mass specific capacity, namely, the electric quantity which can be discharged by a battery or an active substance of unit mass; the other is the volumetric capacity, i.e., the amount of electricity that can be discharged per unit volume of the battery or active material.

Supramolecular polymers are polymers of arrays of repeating units linked by reversible and directional non-covalent interactions. Supramolecular polymers may be formed based on a variety of intermolecular interactions and their synergistic or multiplex interactions, such as hydrogen bonding, coordination, host-guest interactions, charge transfer interactions, pi-pi interactions, etc. The supramolecular polymers can be mainly classified into hydrogen bond type supramolecular polymers, complex type supramolecular polymers, pi-pi type supramolecular polymers and mixed type supramolecular polymers according to different non-covalent bond binding forces. Wherein the hybrid supramolecular polymer contains a plurality of non-covalent bonds.

A crosslinked structure: the cross-linked structure refers to a macromolecule with a three-dimensional network structure formed by connecting linear macromolecule chains through branched chains or chemical bonds.

Linear structure: a straight structure is a structure without branches.

And (3) a secondary battery: the term "rechargeable battery" refers to a battery that can be continuously used by activating an active material by charging after the battery is discharged.

The application provides an electronic device. The electronic device is of the type comprising a battery 10. Referring to fig. 1, fig. 1 illustrates various structural forms of an electronic device 100 according to some embodiments of the present application. Specifically, the electronic device 100 includes, but is not limited to, portable electronic products such as a mobile phone 100A, a tablet computer (tablet personal computer) 100B, a laptop computer (laptop), a personal digital assistant (personal digital assistant, PDA), a personal computer, a Notebook computer (Notebook) 100C, an electric toothbrush 100E, a robot cleaner 100D, a mobile power supply 100F, an unmanned aerial vehicle, an electric car, and the like.

The electronic device 100 further includes an electrical device including, but not limited to, at least one of a display, a speaker, a camera, a flash, a receiver, a motherboard, a sub-board, and a sensor. The battery 10 is electrically connected to the electric device to supply power to the electric device.

Referring to fig. 2 and 3, fig. 2 is a front view of a battery 10 according to some embodiments of the present application, and fig. 3 is a schematic cross-sectional view of the battery 10 at line A-A shown in fig. 2. In the present embodiment, the battery 10 is a secondary battery. Specifically, the battery 10 is a secondary lithium battery. The battery 10 includes a case 2, an electrolyte 3, and an electric cell 1.

It will be appreciated that fig. 2 and 3, and the associated figures below, schematically illustrate only some of the components that the battery 10 includes, the actual shape, actual size, actual location, and actual configuration of which are not limited by fig. 2 and 3, and the figures below.

The housing 2 is used to encapsulate and protect the electrolyte 3 and the cell 1. The shape of the housing 2 includes, but is not limited to, a rectangular parallelepiped, a cylinder, a truncated cone, or the like.

The material of the housing 2 may be metal, such as steel, copper or aluminum, or may be a composite film. When the material of the housing 2 is a composite film. Specifically, the composite film is at least divided into three layers, wherein the middle layer is a metal coating layer which plays a role in isolating moisture, and the outer layer is a plastic coating layer which plays a role in preventing air, especially oxygen, from penetrating; the inner layer is a sealing layer, and plays roles in sealing and preventing the electrolyte 3 from corroding the metal coating layer. The material of the sealing layer is at least one selected from polyethylene, polypropylene, an esterified product of polyethylene or polypropylene, and an ionomer of polyethylene or polypropylene, and the polyethylene is selected from low-density polyethylene, medium-density polyethylene or high-density polyethylene; the polypropylene is selected from homo-, block-or random-polypropylene. The metal coating layer is made of at least one of metal, metal alloy, metal oxide or ceramic, wherein the metal is selected from aluminum, iron, silver, copper, nickel, manganese, tin, titanium, zirconium or vanadium; the plastic coating layer is made of at least one of polyamide resin, polyolefin, polycarbonate or fluororesin. The composite film can be an aluminum plastic film, wherein the middle layer of the aluminum plastic film is an aluminum layer, so that the effect of isolating moisture is achieved, and the outer layer of the aluminum plastic film is polyamide, so that the effect of preventing air, especially oxygen, from penetrating is achieved; the inner layer of the aluminum plastic film is a polypropylene layer, which plays roles of sealing and preventing the electrolyte 3 from corroding the aluminum layer.

The electrolyte 3 is enclosed in the case 2. The electrolyte 3 is a carrier for transporting lithium ions in the battery 10, and the electrolyte 3 is generally prepared from high-purity organic solvent, electrolyte lithium salt, necessary additives and other raw materials under certain conditions and in a certain proportion.

The battery cell 1 is arranged in the shell 2 and is immersed in the electrolyte 3. With continued reference to fig. 3, the battery cell 1 includes a positive electrode tab 12, a negative electrode tab 11, and a separator 13. Positive electrode tab 12 and negative electrode tab 11 are separated by separator 13.

In some embodiments, referring to fig. 3, the battery cell 1 may be a coiled structure. The cell 1 is formed by winding a film. Specifically, the diaphragm includes two diaphragms 13 (i.e., a first diaphragm and a second diaphragm). The membrane is formed by sequentially laminating a positive electrode plate 12, a first membrane, a negative electrode plate 11 and a second membrane. The positive pole piece 12 and the negative pole piece 11 can be separated by a diaphragm 13, so that the insulation and isolation effects are achieved, and the two poles are prevented from being short-circuited.

In other examples, the cell 1 may also be a laminated structure. Specifically, the positive electrode sheet 12 and the negative electrode sheet 11 are alternately stacked in this order, and a separator 13 is provided between the adjacent positive electrode sheet 12 and negative electrode sheet 11. The diaphragm 13 plays a role of insulation and isolation. The membrane 13 may be a membrane bag, a membrane 13 folded along a zigzag shape, or a plurality of single-piece membranes 13, and the application is not limited to the specific structural form of the membrane 13 in the laminated cell 1, as long as the positive electrode pole piece 12 and the negative electrode pole piece 11 can be insulated and isolated.

The material of the separator 13 may be, for example, a polyolefin porous film.

Referring to fig. 4, fig. 4 is a schematic cross-sectional view of the positive electrode tab 12 in the battery 10 shown in fig. 3. The positive electrode sheet 12 includes a positive electrode current collector 121 and a positive electrode polar material layer 122 disposed on a surface of the positive electrode current collector 121.

Specifically, the positive electrode polar material layer 122 may be disposed on one side surface in the thickness direction of the positive electrode current collector 121, or may be disposed on both side surfaces in the thickness direction of the positive electrode current collector 121.

The positive electrode collector 121 serves to collect current. The positive electrode current collector 121 is formed of aluminum (chemical formula: al). The positive electrode polar material layer 122 is a material that participates in the charge-discharge reaction. The material of the positive electrode polar material layer 122 includes a lithium compound. Wherein the lithium compound includes, but is not limited to, lithium iron phosphate (formula: liFePO) ₄ ) Lithium nickelate (chemical formula: li (Li) _x NiO ₂ ) Lithium cobaltate (chemical formula: li (Li) _x CoO ₂ ) Lithium manganate (chemical formula: li (Li) _x MnO ₄ ) And a ternary material, illustratively, a ternary material selected from ternary materials having the designations NCM811, NCM622, NCM523, NCM111, or NCA.

Referring to fig. 5, fig. 5 is a schematic cross-sectional structure of a negative electrode tab 11 in the battery 10 shown in fig. 3. The negative electrode tab 11 includes a negative electrode current collector 111 and a negative electrode polar material layer 112 provided on a surface of the negative electrode current collector 111.

Specifically, the anode polar material layer 112 may be provided on one side surface in the thickness direction of the anode current collector 111, or may be provided on both side surfaces in the thickness direction of the anode current collector 111.

The negative electrode current collector 111 is used to collect current. The negative electrode current collector 111 is formed of copper (chemical formula: cu). The anode polar material layer 112 is a material that participates in the charge-discharge reaction.

Generally, the material of the anode polar material layer 112 includes a conductive additive, an anode active material, and a binder.

Silicon-based materials are active materials with much higher gram capacity than graphite. The silicon-based material has the advantages of higher volume specific capacity, moderate lithium intercalation and deintercalation potential, abundant reserves, low price, environmental protection, no toxicity and the like. Therefore, when selecting the anode active material, silicon-based material particles are desirably selected. That is, the anode active material generally includes silicon-based material particles.

However, since silicon-based materials have a large volume effect, the rate of change of volume due to expansion/contraction thereof is large in the process of repeatedly extracting lithium (i.e., charge and discharge). Therefore, in the process of charging and discharging the battery 10, internal stress accumulation of the silicon-based material particles is easily caused, and finally, the silicon-based material particles are expanded, ruptured and pulverized, and simultaneously, the SEI film is damaged, so that the ruptured silicon-based material particles are in contact with the electrolyte, and therefore, a new SEI film can be regenerated at the damaged part of the SEI film, and lithium ions in the electrolyte are consumed. In addition, the expansion and rupture of the silicon-based material particles also damages the conductive network of the negative electrode, so that part of active substances cannot participate in the reaction, and capacity loss is caused. Meanwhile, due to the volume deformation of the silicon-based material, the negative electrode polar material layer 112 generates and accumulates larger stress, so that the negative electrode polar material layer 112 is broken, and further electrical contact between silicon-based material particles and between the silicon-based material particles and a current collector is lost, even part of the negative electrode polar material layer 112 falls off from the current collector, and the internal resistance and capacity loss of the battery 10 are increased.

In order to solve the above-mentioned technical problems, please refer to fig. 6, fig. 6 is a schematic diagram of another negative electrode 11 according to an embodiment of the present application. The negative electrode tab 11 is applied to the cell 1 of the battery 10 described above.

The negative electrode tab 11 in this embodiment includes a negative electrode current collector 111 and a negative electrode polar material layer 112 provided on a surface of the negative electrode current collector 111.

The material of the negative electrode current collector 111 in this embodiment is the same as that of the negative electrode current collector 111 in the above-described embodiment.

The anode polar material layer 112 includes active material particles 1121 and a conductive additive 1122.

With continued reference to fig. 6, the active material particles 1121 include an inner core 11212 and a flexible cladding 11211.

Wherein the material of the inner core 11212 comprises silicon-based material particles. Illustratively, the core 11212 is a silicon-based material particle, that is, the core 11212 includes only silicon-based material particles and no other materials. Also for example, the core 11212 may include other materials, such as graphite particles, in addition to silicon-based material particles.

Specifically, the silicon-based material particles include at least one of silicon particles, silica particles, silicon oxide particles, and silicon-carbon composite particles. That is, the silicon-based material particles include one or more of silicon particles, silicon dioxide particles, silicon oxide particles, silicon carbon composite particles.

Illustratively, the silicon-based material particles are silicon particles, silicon dioxide particles, silicon oxide particles, or silicon-carbon composite particles.

Also exemplary, the silicon-based material particles include two or more of silicon particles, silicon dioxide particles, silicon oxide particles, and silicon carbon composite particles. For example, the silicon-based material particles include silicon particles and silicon dioxide particles. Alternatively, the silicon-based material particles include silicon particles and silicon oxide particles. Alternatively, the silicon-based material particles include silicon particles and silicon-carbon composite particles. Alternatively, the silicon-based material particles include silicon particles, silica particles, and silica particles. Alternatively, the silicon-based material particles include silicon particles, silica particles, and silicon-carbon composite particles. Alternatively, the silicon-based material particles include silicon particles, silica particles, and silicon-carbon composite particles.

The flexible cladding 11211 wraps around the inner core 11212. For example, the flexible coating 11211 conforms to and wraps the outer surface of the inner core 11212, thus having a simple structure and being convenient for manufacturing. Also exemplary, the flexible cover 11211 surrounds the inner core 11212, and one or more flexible cover layers surrounding the inner core 11212 may be additionally disposed between the flexible cover 11211 and the inner core 11212.

The flexible coating 11211 comprises a material including a supramolecular polymer. Since supramolecular polymers are a class of polymers that are linked by non-covalent bonds. The interaction of the non-covalent bonds is reversible, i.e., the non-covalent bonds in the supramolecular polymer can be broken and formed continuously. Therefore, the supermolecular polymer can respond to a certain external stimulus, and the stimulus is withdrawn to restore the initial state. Specifically, referring to fig. 7, fig. 7 is a schematic diagram showing a volume change of the active material particles 1121 in the negative electrode tab 11 shown in fig. 6 during charge and discharge. Because the flexible coating layer 11211 coats the silicon-based material particles, when the volume of the silicon-based material particles becomes larger in the charge and discharge process, the non-covalent bonds J in the supramolecular polymer are continuously broken and regenerated, so that the flexible coating layer 11211 can adapt to the volume change of the silicon-based material particles and continuously generate tensile deformation. As the volume of the silicon-based material particles becomes smaller, the non-covalent bonds J in the supramolecular polymer are continually broken and regenerated, enabling the flexible coating 11211 to adapt to the volume changes of the silicon-based material particles, and continually shrink deformation. Therefore, the flexible coating layer 11211 has excellent elastic deformability. In addition, the supramolecular polymer also has certain adhesive properties, thus allowing the flexible cover 11211 to have certain adhesive capabilities.

In this way, during the charge and discharge process of the battery 10, the flexible coating 11211 can generate a certain constraint effect on the volume expansion of the inner core 11212, so as to relieve the internal stress generated by the volume change of the inner core 11212 to a certain extent, thereby reducing the risk of expansion and rupture of the inner core 11212 to a certain extent, and further reducing the risk of damaging the conductive network of the negative electrode. And the flexible coating layer 11211 can also play a role in isolating the inner core 11212 and the electrolyte 3, so that the problem of regeneration due to SEI film rupture is avoided, the consumption of lithium ions is avoided, and the capacity and the service life of the battery are improved. In addition, the problem of large stress accumulation at the negative electrode polar material layer 112 caused by the volume change of the inner core 11212 can be prevented to a certain extent, so that the breakage of the negative electrode polar material layer 112 is avoided, the problem that electrical contact between silicon-based material particles and between the silicon-based material particles and the negative electrode current collector 111 is lost, and the problem that part of the negative electrode polar material layer 112 falls off from the negative electrode current collector 111 is avoided, thereby being beneficial to improving the capacity and the service life of the battery 10. In addition, since the supramolecular polymer has a certain adhesion property, in the anode polar material layer 112, adhesion between two adjacent active material particles 1121 and between the active material particles 1121 and the conductive additive is facilitated by the flexible coating layer 11211 (refer to fig. 6), improving the structural strength of the anode polar material layer 112, and also facilitating the improvement of the bonding strength between the anode polar material layer 112 and the anode current collector 111, thereby further preventing the problems of increased internal resistance and capacity loss of the battery 10 caused by the falling-off of a part of the anode polar material layer 112 from the anode current collector 111, and facilitating the replacement of the binder in the above embodiment with the supramolecular polymer, thereby facilitating the omission of the setting of the binder and the reduction of the material cost.

In some embodiments, the supramolecular polymer is a hydrogen-bonding supramolecular polymer. That is, the non-covalent bonding means employed in supramolecular polymers include hydrogen bonding. For example, the non-covalent bonding means employed in supramolecular polymers are only hydrogen bonds. Because the supermolecular polymer connected by hydrogen bonds has excellent reversibility, the supermolecular polymer has the advantages of good film forming property, strong elastic deformation capability and strong ductility. In addition, the hydrogen bond type supermolecular polymer has better adhesive property. When the supramolecular polymer is a hydrogen bond type supramolecular polymer, the internal stress generated by the volume change of the inner core 11212 is further relieved in the charge-discharge process of the battery 10, so that the risk of expansion and rupture of the inner core 11212 is further reduced, and the risk of damage to the conductive network of the negative electrode is further reduced. In addition, the problem of relatively large stress accumulation at the negative electrode polar material layer 112 due to the volume change of the inner core 11212 can be further prevented, so that the breakage of the negative electrode polar material layer 112 is further avoided, the problem that electrical contact between silicon-based material particles and between the silicon-based material particles and the negative electrode current collector 111 is lost, and the problem that part of the negative electrode polar material layer 112 falls off from the negative electrode current collector 111 is further avoided, thereby being beneficial to further improving the capacity and the service life of the battery 10. The hydrogen bond type supermolecular polymer has good bonding performance, is favorable for further improving the bonding strength between two adjacent active material particles 1121 and between the active material particles 1121 and the conductive additive in the anode polar material layer 112, improves the structural strength of the anode polar material layer 112, and is favorable for further improving the bonding strength between the anode polar material layer 112 and the anode current collector 111, thereby further preventing the problems of internal resistance increase and capacity loss of the battery 10 caused by the falling-off of part of the anode polar material layer 112 from the anode current collector 111.

Of course, it is understood that in other examples, the supramolecular polymer may also be other types of supramolecular polymers, such as the complex-type supramolecular polymers or pi-type supramolecular polymers described previously.

In some embodiments, the flexible coating 11211 may be formed directly from a supramolecular polymer. Thus, the material composition is simple, the manufacturing is convenient, the cost is reduced, and the elastic deformability and the adhesive property of the flexible coating 11211 are improved.

Of course, it is understood that in other examples, the flexible cover 11211 may also include an electrically conductive material. For example, the flexible coating 11211 is formed by mixing a supramolecular polymer and a conductive material. In this way, the flexible coating 11211 can be used to conduct electricity, so that a conductive network can be formed between the core 11212 and the conductive additive 1122, and the charge and discharge efficiency of the battery 10 can be improved.

In some embodiments, the negative electrode polar material layer 112 is composed of the conductive additive 1122 and the active material particles 1121. That is, only two types of materials, namely, the conductive additive 1122 and the active material particles 1121, are included in the negative electrode polar material layer 112, and the binder is not included. Thereby, the material cost is reduced.

In some embodiments, the conductive additive 1122 may include additives in the form of two of particulate additives, wire additives, and platelet additives. For example, conductive additive 1122 includes a particulate additive and a linear additive. As another example, conductive additive 1122 includes both particulate additives and platelet additives. For another example, conductive additive 1122 includes a linear additive and a platelet additive. In other examples, conductive additive 1122 may include additives in the form of three types of particulate additives, wire additives, and flake additives. As long as it is ensured that the conductive additive 1122 includes at least two forms of additives among a particulate additive, a linear additive, and a plate-like additive.

In this way, the conductive additives 1122 in different forms can be mutually filled, the contact area between the conductive additives 1122 is increased, and the distribution density of the conductive additives 1122 in the negative electrode polar material layer 112 is increased, so that a conductive network can be constructed in the negative electrode polar material layer 112 by using the conductive additives 1122 in different forms, and a conductive path is formed. And, the conductive additives 1122 in different forms are mutually filled to increase the contact area, which is beneficial to ensuring the conductivity of the anode polar material layer 112 under the premise of lower doping amount of the conductive additives 1122. In addition, the degree of mutual embedding of the conductive additive 1122 in different forms and the flexible coating layer 11211 is different, and the use of the conductive additive 1122 in different forms is beneficial to make up for the problem that a conductive path cannot be formed with the inner core 11212 due to weak embedding ability of the conductive additive 1122 in a single form and the flexible coating layer 11211, and is more beneficial to the construction of the conductive path between the inner core 11212 and the conductive additive 1122 in the active material particles 1121.

It is noted that, in the present application, linear additives refer to additives that extend in a linear shape, for example, one-dimensional form, including but not limited to, a linear shape, a curved shape, or a broken line shape. A lamellar additive refers to an additive that is particularly thin in thickness in one dimension, while forming a lamellar shape, for example, an additive in a two-dimensional form. Particulate additives are additives that are spherical or irregular in shape, and that do not differ substantially in size in all directions, for example, three-dimensional additives. In other examples, the conductive additive 1122 may be in the form of one of a granular additive, a linear additive, and a plate additive.

In some specific examples, the linear additive includes carbon nanotubes and/or carbon fibers. That is, the linear additive may be carbon nanotubes, carbon fibers, or both carbon nanotubes and carbon fibers.

The carbon nanotubes may be classified into single-walled carbon nanotubes and multi-walled carbon nanotubes. The carbon nano tube with a one-dimensional structure is similar to a fiber in a long column shape, and the inside of the carbon nano tube is hollow. The carbon nano tube has good mechanical properties, specifically, the carbon nano tube has high elastic modulus and high strength, and the structural stability of the carbon nano tube is high. The carbon nanotubes are used as the conductive additive 1122 to well distribute a perfect conductive network, which is in a dotted line contact form with the active material particles 1121, so as to facilitate the improvement of the conductivity of the negative electrode tab 11 and the capacity of the battery 10.

The carbon fiber is a fiber material with high strength and high elastic modulus and carbon content of more than 90%. Besides good mechanical properties, the carbon fiber has good high temperature resistance and friction resistance, and the carbon fiber has light weight. By using carbon fiber as the conductive additive 1122, a good conductive network is easily formed, exhibiting good conductivity, thus reducing electrode polarization, reducing internal resistance of the battery 10, and improving the performance of the battery 10. The carbon fiber is also in dotted contact with the active material particles 1121, which is advantageous for improving the conductivity of the negative electrode tab 11 and improving the capacity of the battery 10.

In some embodiments, the platelet additive includes Graphene (Graphene) in a platelet form and/or graphite in a platelet form. Illustratively, the graphene in the form of a sheet may be a single-layer graphene, a double-layer graphene, or a few-layer graphene.

Wherein, single-layer Graphene (Graphene): refers to a two-dimensional carbon material composed of a layer of carbon atoms periodically closely packed in a benzene ring structure (i.e., a hexagonal honeycomb structure).

Bilayer graphene refers to a two-dimensional carbon material formed by stacking two layers of carbon atoms which are periodically and closely stacked in a benzene ring structure (namely a hexagonal honeycomb structure) in different stacking modes (comprising AB stacking, AA stacking and the like).

The few-layer graphene refers to a two-dimensional carbon material formed by stacking 3-10 layers of carbon atoms which are periodically and closely stacked in a benzene ring structure (namely, a hexagonal honeycomb structure) in different stacking modes (including ABC stacking, ABA stacking and the like).

The graphene has high structural strength and good toughness. And because of the unique sheet structure (two-dimensional structure), the contact with the active material particles 1121 is point-surface contact, so that the purpose of the conductive additive 1122 can be exerted to the greatest extent, a good conductive network can be easily formed, good conductivity can be shown, and the active material particles 1121 can be used more on the premise of reducing the use amount of the conductive additive 1122, and the capacity of the battery 10 can be improved.

Similarly, the graphite flakes may be single-layered or 2-10 layered.

The flake graphite also has better conductivity, and the flake graphite and the active material particles 1121 are in a point-surface contact mode, so that a conductive network structure with a certain scale can be formed, and the conductive efficiency is improved.

In some embodiments, the particulate additive includes carbon black and/or graphite. The high specific surface area and close packing of the carbon black particles are beneficial to close contact between the particles, form a good conductive network and are beneficial to improving conductivity.

The graphite also has better conductivity, and the graphite particles and the active material particles 1121 are in a point contact mode, so that a conductive network structure with a certain scale can be formed, and the conductive efficiency is improved.

In some embodiments, the peel strength of the flexible cover 11211 ranges from greater than or equal to 10N/m. That is, in the negative electrode tab 11, when the flexible coating 11211 is peeled from the core 11212, the peeling strength is required to be in the range of 10N/m or more. Therefore, the bonding strength between the flexible coating layer 11211 and the inner core 11212 is high, so that the bonding strength between the active material particles 1121 and the negative electrode current collector 111 is improved, and the situation that part of the negative electrode polar material layer 112 is peeled off from the negative electrode current collector 111 and enters the electrolyte 3 in the charge-discharge process of the battery 10 can be effectively avoided. Furthermore, the problems of increased internal resistance and capacity loss of the battery 10 caused by the loss of electrical contact between the silicon-based material particles and the negative electrode current collector 111 due to the breakage and peeling of part of the negative electrode polar material layer 112, and even the falling of part of the negative electrode polar material layer 112 from the negative electrode current collector 111, can be avoided, which is beneficial to the improvement of the capacity of the battery 10.

Illustratively, the peel strength of the flexible cover 11211 has a range of values less than or equal to 20N/m. Thus, the flexible cover 11211 can be made of a convenient material. For example, the peel strength of the flexible coating 11211 may be 11N/m, 12N/m, 13N/m, 14N/m, or 15N/m.

It should be noted that, in testing the peel strength of the flexible coating layer 11211, the active material particles 1121 may be first separated from the anode polar material layer 112. The test was then performed using a peel force tester (also known as a composite strength tester, 180 degree peel force tester, peel tester, electronic peel tester).

In some embodiments, the flexible cover 11211 has a range of values for the modulus of elasticity: 0.3GPa to 8GPa. Thereby, it is advantageous to ensure the elastic deformability of the flexible coating layer 11211.

Illustratively, the elastic modulus of the flexible coating 11211 is given by: 0.5GPa, 0.6GPa, 0.8GPa, 0.9GPa, 1GPa, 1.2GPa, 1.5GPa, 1.7GPa, 1.8GPa, 2GPa, 2.1GPa, 2.5GPa, 2.8GPa, 3GPa, 3.2GPa, 3.5GPa, 3.8GPa, 4GPa, 4.2GPa, 4.5GPa, 4.8GPa, 5.2GPa, 5.5GPa, 5.8GPa, 6GPa, 6.2GPa, 6.5GPa, 6.7GPa, 7.2GPa, 7.5GPa, or 7.8GPa. Thereby, it is advantageous to ensure the elastic deformability of the flexible coating layer 11211.

In some embodiments, the material forming the supramolecular polymer includes a first material and a second material.

Wherein the first material comprises a polyacid and/or a polyanhydride. Illustratively, the first material is a polyacid or a polyanhydride. Also exemplary, the first material is a combination of a polyacid and a polyanhydride. Wherein the polyanhydride is formed by dehydration of a polyacid.

Illustratively, the polyacids include one or more of monomeric, dimeric, and trimeric fatty acids. Illustratively, the polyacid is a monomeric, dimeric or trimeric fatty acid. Also exemplary, the polyacid includes two of a monomeric fatty acid, a dimeric fatty acid, and a trimeric fatty acid, e.g., the polyacid includes a monomeric fatty acid and a dimeric fatty acid. As another example, the polyacids include monomeric fatty acids and trimeric fatty acids. For another example, the polyacids include dimer fatty acids and trimer fatty acids. Still more exemplary, the polyacids include monomeric, dimeric and trimeric fatty acids.

The second material comprises a polyol and/or a polyamine. Illustratively, the second material is a polyol or a polyamine. Also exemplary, the second material is a combination of a polyol and a polyamine.

Exemplary polyamines include, but are not limited to, at least one of diethylenetriamine, triethylenetetramine, ethylenediamine, propyltriamine, and the like. Exemplary polyamines include diethylenetriamine, triethylenetetramine, ethylenediamine, or propyltriamine. Still further exemplary polyamines include diethylenetriamine and triethylenetetramine. Still more exemplary, polyamines include diethylenetriamine and ethylenediamine. Still more exemplary, polyamines include triethylenetetramine and ethylenediamine. Still more exemplary polyamines include diethylenetriamine, triethylenetetramine, and ethylenediamine.

Exemplary polyols include ethylene glycol and/or glycerol.

The supermolecular polymer formed by the first material and the second material has good elastic deformation capability and bonding performance, and the material has low price and low cost.

In some embodiments, the weight parts of the first material range from 2 parts to 10 parts when the weight parts of the second material are 1 part. Therefore, the proportion of the first material and the second material is reasonable, and the supermolecular polymer with excellent elastic deformation capability and bonding performance is obtained.

The weight portion is the mass ratio of each of several substances, wherein 1 part is taken as an example, the mass of the second material is 1g, and the mass of the first material is 2 g-10 g. That is, when the mass of the second material is 1g, the mass of the first material is any value from 2g to 10g.

In some embodiments, the weight parts of the first material range from 4 parts to 8 parts when the weight parts of the second material are 1 part. Therefore, the proportion of the first material and the second material is more reasonable, and the supermolecular polymer with excellent elastic deformation capability and bonding performance is obtained.

Illustratively, the weight of the first material is 4.5, 5, 5.5, 6, 6.5, 7 or 7.5 parts when the weight of the second material is 1 part.

In some embodiments, the ratio of the equivalent diameter of the active material particles 1121 to the equivalent diameter of the inner core 11212 is greater than 1 and less than or equal to 1.3. Thus, by defining the ratio of the equivalent diameter of the active material particles 1121 to the equivalent diameter of the inner core 11212 to be greater than 1 and less than or equal to 1.3, it is advantageous to define the thickness of the flexible coating layer 11211 within a reasonable range, on the one hand, to ensure the elastic deformability and adhesive properties of the flexible coating layer 11211, and on the other hand, to ensure the structural strength of the flexible coating layer 11211.

Illustratively, the ratio of the equivalent diameter of the active material particles 1121 to the equivalent diameter of the inner core 11212 is 1.1, 1.15, 1.18, 1.2, 1.21, 1.23, 1.25, 1.26, 1.28, or 1.29.

Equivalent diameter refers to equivalent sphere diameter (equivalent spherical diameter, ESD) and refers to an irregularly shaped object that has the same volume as the diameter of a sphere. The equivalent diameter of the active material particles 1121 is the diameter of a sphere having the same volume as the outer surface of the active material particles 1121. When the active material particles 1121 are spherical, the equivalent diameter is the outer diameter of the active material particles 1121. Similarly, the equivalent diameter of the inner core 11212 is the diameter of a sphere of the same volume as the outer surface of the inner core 11212. When the inner core 11212 is spherical, the equivalent diameter is the outer diameter of the inner core 11212.

In some examples, the equivalent diameter of the inner core 11212 is on the order of nanometers, i.e., the equivalent diameter of the inner core 11212 is greater than or equal to 1 nanometer (nm) and less than 1000nm. In particular, the core 11212 equivalent may be 5nm, 10nm, 20nm, 100nm, 200nm, 500nm, 800nm, 900nm, or 950nm. In this way, compared with the large-sized core 11212, the volume effect of the core 11212 in the charge and discharge process of the battery 10 is reduced, more active material particles 1121 are uniformly distributed in the negative electrode polar material layer 112, and the charge and discharge efficiency of the battery 10 is improved.

In still other examples, the equivalent diameter of the inner core 11212 is on the order of microns. That is, the equivalent diameter of the core 11212 is greater than or equal to 1 micrometer (um) and less than 1000um. Specifically, the equivalent diameter of the core 11212 may be 5um, 10um, 20um, 100um, 200um, 500um, 800um, 900um, or 950um. Thus, the flexible coating layer 11211 is formed on the inner core 11212 more advantageously, and the bonding strength between the flexible coating layer 11211 and the inner core 11212 is improved.

In some embodiments, the equivalent diameter of the core 11212 ranges from 10nm to 30um, i.e., from 10nm to 30000nm. In this way, on the one hand, it is advantageous to prevent the problem that the equivalent diameter of the inner core 11212 is too small, which is disadvantageous in that the flexible coating 11211 is formed on the surface of the inner core 11212, and the bonding strength between the flexible coating 11211 and the inner core 11212 is weak, and on the other hand, it is advantageous to prevent the problem that the volume change of the inner core 11212 during the charge and discharge process is too large due to the too large size of the inner core 11212. That is, the equivalent diameter of the inner core 11212 ranges from 10nm to 30um, so that the size design of the inner core 11212 is more reasonable, the connection strength between the flexible coating 11211 and the inner core 11212 can be ensured, the volume change of the inner core 11212 in the charge and discharge process of the battery 10 can be weakened, more active material particles 1121 are uniformly distributed in the negative electrode polar material layer 112, and the charge and discharge efficiency of the battery 10 is improved.

Illustratively, the equivalent diameter of the core 11212 has a value in the range of 80nm to 25um. Further, the equivalent diameter of the core 11212 is in the range of 150nm to 10um.

The application also provides a processing method of the negative electrode plate 11 in the embodiment. Referring to fig. 8, fig. 8 is a flowchart of a processing method of the negative electrode 11 according to an embodiment of the application. The processing method comprises the following steps:

s10: a negative electrode polar material layer 112 is provided on the surface of the negative electrode current collector 111.

Illustratively, the material of the negative electrode current collector 111 is copper.

The anode polar material layer 112 includes active material particles 1121 and a conductive additive 1122. The active material particles 1121 include an inner core 11212 and a flexible cladding 11211.

The flexible coating 11211 comprises a material including a supramolecular polymer. Since supramolecular polymers are a class of polymers that are linked by non-covalent bonds. The interaction of the non-covalent bonds is reversible, i.e., the non-covalent bonds in the supramolecular polymer can be broken and formed continuously. Therefore, the supermolecular polymer can respond to a certain external stimulus, and the stimulus is withdrawn to restore the initial state. In the charge and discharge process, when the volume of the silicon-based material particles becomes larger, the non-covalent bonds J in the supramolecular polymer are continuously broken and regenerated, so that the flexible coating 11211 can adapt to the volume change of the silicon-based material particles and continuously generate tensile deformation. As the volume of the silicon-based material particles becomes smaller, the non-covalent bonds J in the supramolecular polymer are continually broken and regenerated, enabling the flexible coating 11211 to adapt to the volume changes of the silicon-based material particles, and continually shrink deformation. Therefore, the flexible coating layer 11211 has excellent elastic deformability. In addition, the supramolecular polymer also has certain adhesive properties, thus allowing the flexible cover 11211 to have certain adhesive capabilities.

In this way, during the charge and discharge process of the battery 10, the flexible coating 11211 can generate a certain constraint effect on the volume expansion of the inner core 11212, so as to relieve the internal stress generated by the volume change of the inner core 11212 to a certain extent, thereby reducing the risk of expansion and rupture of the inner core 11212 to a certain extent, and further reducing the risk of damaging the conductive network of the negative electrode. And the flexible coating layer 11211 can also play a role in isolating the inner core 11212 and the electrolyte 3, so that the problem of regeneration due to SEI film rupture is avoided, the consumption of lithium ions is avoided, and the capacity and the service life of the battery are improved. In addition, the problem of large stress accumulation at the negative electrode polar material layer 112 caused by the volume change of the inner core 11212 can be prevented to a certain extent, so that the breakage of the negative electrode polar material layer 112 is avoided, the problem that electrical contact between silicon-based material particles and between the silicon-based material particles and the negative electrode current collector 111 is lost, and the problem that part of the negative electrode polar material layer 112 falls off from the negative electrode current collector 111 is avoided, thereby being beneficial to improving the capacity and the service life of the battery 10. In addition, since the supramolecular polymer has a certain adhesion property, in the anode polar material layer 112, adhesion between two adjacent active material particles 1121 and between the active material particles 1121 and the conductive additive is facilitated by the flexible coating layer 11211, the structural strength of the anode polar material layer 112 is improved, and the bonding strength between the anode polar material layer 112 and the anode current collector 111 is also facilitated, so that the problems of increased internal resistance and capacity loss of the battery 10 caused by falling off of part of the anode polar material layer 112 from the anode current collector 111 are further prevented, and the use of the supramolecular polymer instead of the adhesive in the above embodiment is also facilitated, thereby facilitating the omission of the setting of the adhesive and the reduction of the material cost.

It should be noted that step S10 may specifically include: a negative electrode polar material layer 112 is provided on one side surface in the thickness direction of the negative electrode current collector 111 such that the negative electrode polar material layer 112 is in contact with a single side surface of the negative electrode current collector 111. Step S10 may specifically include: a negative electrode polar material layer 112 is provided on both side surfaces in the thickness direction of the negative electrode current collector 111 such that the negative electrode polar material layer 112 is in contact with a single side surface of the negative electrode current collector 111.

In some embodiments, referring to fig. 9, fig. 9 is a specific flowchart of step S10 in the processing method of the negative electrode tab 11 shown in fig. 8. In this embodiment, the step S10 specifically includes the following steps:

and step S11, heating the first material and the second material in a protective gas atmosphere to enable the first material and the second material to react so as to obtain the supermolecular polymer slurry.

Wherein the protective gas may be nitrogen or an inert gas. Inert gases include, but are not limited to, argon and helium.

In some embodiments, the first material comprises a polyacid and/or a polyanhydride. Illustratively, the first material is a polyacid or a polyanhydride. Also exemplary, the first material is a combination of a polyacid and a polyanhydride. Wherein the polyanhydride is formed by dehydration of a polyacid.

Exemplary polyols include ethylene glycol and/or glycerol.

Specifically, when the weight part of the second material is 1 part, the value of the weight part of the first material ranges from 4 parts to 8 parts. Thus, a supramolecular polymer excellent in both elastic deformability and adhesive properties can be advantageously obtained.

Specifically, step S11 may include: the first material and the second material are fully mixed and reacted with a stirrer under a protective gas atmosphere to obtain the supramolecular polymer slurry. Thus, the mixing uniformity can be improved. Among them, the mixers include, but are not limited to, propeller type mixers, turbine type mixers, paddle type mixers, anchor type mixers, ribbon type mixers, magnetic heating mixers, hinge type mixers, variable frequency double layer mixers, and side entry type mixers.

Step S12, disposing a supramolecular polymer slurry on a surface of the inner core 11212 to form active material particles 1121 having a flexible coating layer 11211;

specifically, in step S12, a supramolecular polymer slurry is coated on the outer surface of the inner core 11212 to form active material particles 1121 having a flexible coating layer 11211.

As such, the flexible coating 11211 is formed of only a supramolecular polymer, i.e., the flexible coating 11211 is formed of a single supramolecular polymer material. In this way, the material composition is simple, the manufacturing is convenient, the cost is reduced, and the elastic deformation capability and the bonding performance of the flexible coating 11211 are improved.

In some embodiments, the peel strength of the flexible cover 11211 ranges from greater than or equal to 10N/m. That is, when the flexible coating 11211 is peeled from the inner core 11212, the peeling strength is required to be in the range of 10N/m or more. Therefore, the bonding strength between the flexible coating layer 11211 and the inner core 11212 is high, so that the bonding strength between the active material particles 1121 and the negative electrode current collector 111 is improved, and the situation that part of the negative electrode polar material layer 112 is peeled off from the negative electrode current collector 111 and enters the electrolyte 3 in the charge-discharge process of the battery 10 can be effectively avoided. Furthermore, the problems of increased internal resistance and capacity loss of the battery 10 caused by the loss of electrical contact between the silicon-based material particles and the negative electrode current collector 111 due to the breakage and peeling of part of the negative electrode polar material layer 112, and even the falling of part of the negative electrode polar material layer 112 from the negative electrode current collector 111, can be avoided, which is beneficial to the improvement of the capacity of the battery 10.

Step S13, thoroughly mixing the active material particles 1121 and the conductive additive 1122 to obtain a polar slurry;

specifically, step S13 may include: the active material particles 1121 and the conductive additive 1122 are thoroughly mixed using a stirrer to obtain a polar slurry. Thus, the mixing uniformity can be improved.

Step S14, a polar paste is disposed on the surface of the negative electrode current collector 111 to obtain a negative electrode polar material layer 112.

Specifically, step S14 may include: the polar paste is coated on the surface of the anode current collector 111 to obtain an anode polar material layer 112.

In this way, the anode polar material layer 112 is formed by the conductive additive 1122 and the active material particles 1121, saving the binder, and contributing to the reduction of material cost. Further, the anode polar material layer 112 may be closely attached to the anode current collector 111, and the bonding strength between the anode polar material layer 112 and the anode current collector 111 can be improved. The method is simple, the conditions are easy to control, and the method is suitable for industrial production.

In some embodiments, the conductive additive 1122 may include additives in the form of two of particulate additives, wire additives, and platelet additives. For example, conductive additive 1122 includes a particulate additive and a linear additive. As another example, conductive additive 1122 includes both particulate additives and platelet additives. For another example, conductive additive 1122 includes a linear additive and a platelet additive. In other examples, conductive additive 1122 may include additives in the form of three types of particulate additives, wire additives, and flake additives.

Of course, it is understood that in other examples, the conductive additive 1122 may be in the form of one of a particulate additive, a wire additive, and a flake additive.

In some embodiments, the platelet additive includes Graphene (Graphene) in a platelet form and/or graphite in a platelet form. The graphene has high structural strength and good toughness. And because of the unique sheet structure (two-dimensional structure), the contact with the active material particles 1121 is point-surface contact, so that the purpose of the conductive additive 1122 can be exerted to the greatest extent, a good conductive network can be easily formed, good conductivity can be shown, and the active material particles 1121 can be used more on the premise of reducing the use amount of the conductive additive 1122, and the capacity of the battery 10 can be improved.

Referring to fig. 10, fig. 10 is a specific flowchart of step S12 in the processing method of the negative electrode tab 11 shown in fig. 9. In this embodiment, the step S12 specifically includes the following steps:

step S121: disposing a supramolecular polymer slurry on a surface of the core 11212 to cover the supramolecular polymer slurry on the surface of the core 11212;

step S122: heating the supramolecular polymer slurry on the surface of the inner core 11212 for a second preset time at a second preset temperature;

specifically, the value range of the second preset temperature is 70-120 ℃. The second preset temperature is exemplified by a value ranging from 90 ℃ to 110 ℃. For example, the second preset temperature has a value of 91 ℃, 92 ℃, 93 ℃, 94 ℃, 95 ℃, 96 ℃, 97 ℃, 98 ℃, 99 ℃, 100 ℃, 101 ℃, 102 ℃, 103 ℃, 104 ℃, 105 ℃, 106 ℃, 107 ℃, 108 ℃, or 109 ℃.

Specifically, the value range of the second preset time is 3-100 min. The value range of the second preset time is 3 min-10 min. For example, the second preset time has a value of 4min, 5min, 6min, 7min, 8min or 9min.

Step S123: the supramolecular polymer slurry on the surface of the inner core 11212 is cooled to form the flexible cladding 11211.

Because the inner core 11212 comprises silicon-based material particles, the surfaces of the silicon-based material particles are provided with silicon-oxygen bonds, and the supermolecular polymer slurry on the surface of the inner core 11212 is heated, on one hand, the mobility and the diffusivity of the supermolecular polymer slurry are improved, so that the infiltration effect between the supermolecular polymer slurry and the surface of the inner core 11212 is improved, and on the other hand, the bonding strength between the flexible coating 11211 and the inner core 11212 is improved through the two aspects because the non-covalent bonds in the supermolecular polymer are bonded with the silicon-oxygen bonds after being broken.

In some examples, referring to fig. 11, fig. 11 is a specific flowchart of step S121 in the processing method of the negative electrode tab 11 shown in fig. 10. In this embodiment, step S121 may include:

step S1211: setting the supramolecular polymer slurry on the surface of the inner core 11212 at a third preset temperature to cover the supramolecular polymer slurry on the surface of the inner core 11212; wherein the third preset temperature is greater than room temperature and less than the second preset temperature.

Step S1212: the supramolecular polymer slurry is cooled. That is, the supramolecular polymer slurry is cooled to room temperature.

Therefore, at the third preset temperature, the supramolecular polymer slurry is arranged on the surface of the inner core 11212, so that the fluidity and the diffusivity of the supramolecular polymer slurry are improved, the infiltration effect between the supramolecular polymer slurry and the surface of the inner core 11212 is improved, and the bonding strength between the coating layer and the inner core 11212 is improved.

The third preset temperature is exemplified by a value ranging from 40 ℃ to 50 ℃. For example, the third preset temperature is 42 ℃, 45 ℃, 48 ℃, or 49 ℃.

Referring to fig. 12, fig. 12 is another specific flowchart of step S10 in the processing method of the negative electrode tab 11 shown in fig. 8. In this embodiment, the step S10 specifically includes the following steps:

Step S12, disposing a supramolecular polymer slurry on the surface of the inner core 11212 to form active material particles 1121 having a flexible coating layer;

specifically, in step S12, a supramolecular polymer slurry is coated on the surface of the inner core 11212 to form active material particles 1121 having a flexible coating layer.

Step S13, the active material particles 1121, the conductive additive 1122, and the solvent are thoroughly mixed to obtain a polar slurry.

Thus, the addition of the solvent is advantageous in improving the uniformity of mixing between materials.

Specifically, step S13 may include: the active material particles 1121, the conductive additive 1122, and the solvent are thoroughly mixed using a stirrer to obtain a polar slurry. Thus, the mixing uniformity can be improved.

Step S14, a polar paste is disposed on the surface of the negative electrode current collector 111. Specifically, step S14 may include: the polar paste is coated on the surface of the negative electrode current collector 111.

S15: the polar paste on the anode current collector 111 is dried so that the solvent in the polar paste volatilizes to obtain an anode polar material layer 112.

The drying process may be a drying process. The temperature of the drying may be greater than or equal to 70 ℃ and less than or equal to 90 ℃. Specifically, the temperature of the drying may be 70 ℃, 72 ℃, 74 ℃, 76 ℃, 78 ℃, 80 ℃, 84 ℃, 86 ℃, 88 ℃, or 90 ℃.

The solvent includes at least one of water and an organic solvent. That is, the solvent may be water, or an organic solvent, or may include both water and an organic solvent.

The organic solvent comprises ethanol and/or NMP (N-Methylpyrrolidone).

In other examples, the organic solvent may also include at least one of benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, toluene cyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, methanol, isopropanol, diethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, ethyl propionate, acetone, methyl butanone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, acetonitrile, pyridine, and phenol.

Hereinafter, the processing of the negative electrode tab 11 will be described in detail in the form of various examples.

Example 1

And (3) under the protective atmosphere, carrying out crosslinking reaction on the polyacid and diethylenetriamine in a mass ratio of 4-8:1 for 8-24 hours at 150-200 ℃ to prepare the supermolecule polymer slurry. Wherein the polyacid comprises one or more of fatty acid monomer, fatty acid dimer, and fatty acid trimer. The structure of the generated supermolecular polymer slurry is a cross-linked structure, and belongs to hydrogen bond type supermolecular polymers. It is understood that the supramolecular polymer slurry is in a semi-cured state.

Setting the supramolecular polymer slurry on the surface of the core 11212 in an environment of 40 ℃ -50 ℃ (i.e., a third preset temperature); for example, 5ul of slurry is applied to the surface of the core 11212 and spread out. Wherein, the material of the inner core 11212 is silicon-carbon composite particles, and the equivalent diameter is 8um.

And then cooled to room temperature.

The inner core 11212 and the supramolecular polymer slurry on the surface of the inner core 11212 are heated for 5min (i.e., a second preset time) in an environment of 100 ℃ (i.e., a second preset temperature).

The supramolecular polymer slurry is cooled to form active material particles 1121 with a flexible coating 11211. Wherein the thickness of the flexible coating layer 11211 is in the range of 3-5 nm.

Thoroughly mixing the prepared active material particles 1121, conductive carbon black, and single-walled carbon nanotubes to prepare a polar slurry without additional binder;

the polar paste is coated on the surface of the negative electrode current collector 111 to form a negative electrode polar material layer 112.

Example two

In protective atmosphere, the linear reaction of the polyacid and ethylenediamine in the mass ratio of 4-8:1 is carried out for 8-24 hours at 80-160 ℃ to prepare the supermolecular polymer slurry. Wherein the polyacid comprises one or more of fatty acid monomer, fatty acid dimer, and fatty acid trimer. The structure of the generated supermolecular polymer slurry is a linear structure, and belongs to a hydrogen bond type supermolecular polymer. It is understood that the supramolecular polymer slurry is in a semi-cured state.

And then cooled to room temperature.

The inner core 11212 and the supramolecular polymer slurry on the surface of the inner core 11212 are heated for 5min (i.e., a second preset time) in an environment of 100 ℃.

Example III

And (3) under the protective atmosphere, carrying out crosslinking reaction on the polyacid and the glycerol in a mass ratio of 4-8:1 for 8-24 hours at 150-250 ℃ to prepare the supermolecular polymer slurry. Wherein the polyacid comprises one or more of fatty acid monomer, fatty acid dimer, and fatty acid trimer. The structure of the generated supermolecular polymer slurry is a crosslinked structure, and belongs to hydrogen bond type supermolecular polymers. It is understood that the supramolecular polymer slurry is in a semi-cured state.

And then cooled to room temperature.

In the description of the present specification, a particular feature, structure, material, or characteristic may be combined in any suitable manner in one or more embodiments or examples.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A negative electrode tab, comprising:

a negative electrode current collector;

the negative electrode polar material layer is arranged on the surface of the negative electrode current collector, the negative electrode polar material layer comprises active material particles, the active material particles comprise a core and a flexible coating layer, the core is wrapped by the flexible coating layer, the core comprises silicon-based material particles, and the flexible coating layer comprises a supermolecular polymer.

2. The negative electrode tab of claim 1, wherein the flexible coating is adhered to an outer surface of the core.

3. The negative electrode tab of claim 1 or 2, wherein the supramolecular polymer is a hydrogen-bonding supramolecular polymer.

4. A negative electrode sheet according to any one of claims 1-3, characterized in that the flexible coating layer is formed of a supramolecular polymer.

5. The negative electrode sheet according to any one of claims 1 to 4, wherein the peel strength of the flexible coating layer has a value in a range of 10N/m or more.

6. The negative electrode sheet according to any one of claims 1-5, wherein the flexible coating layer has an elastic modulus ranging from 0.3GPa to 8GPa.

7. The negative electrode tab of any one of claims 1-6, wherein the material forming the supramolecular polymer comprises a first material and a second material;

the first material comprises a polyacid and/or a polyanhydride, the polyanhydride being formed from dehydration of the polyacid; wherein the polyacid comprises one or more of a monomeric fatty acid, a dimeric fatty acid and a trimeric fatty acid;

the second material includes a polyol and/or a polyamine.

8. The negative electrode sheet according to claim 7, wherein the value of the weight part of the first material is in the range of 2 to 10 parts when the weight part of the second material is 1 part.

9. The negative electrode sheet according to any one of claims 1-8, characterized in that the negative electrode polar material layer further comprises a conductive additive, the negative electrode polar material layer consisting of the conductive additive and the active material particles.

10. The negative electrode tab of claim 9 wherein the conductive additive comprises both particulate and linear additives; or,

the conductive additive comprises two forms of additives, namely a granular additive and a sheet additive; or,

The conductive additive comprises additives in two forms of linear additives and sheet additives; or,

the conductive additive comprises three forms of additives including a granular additive, a linear additive and a sheet additive.

11. The negative electrode tab of claim 10, wherein the linear additive comprises carbon nanotubes and/or carbon fibers;

the platelet additive comprises platelet graphene and/or platelet graphite;

the particulate additive comprises carbon black and/or graphite.

12. The negative electrode sheet according to any one of claims 1 to 11, characterized in that the ratio of the equivalent diameter of the active material particles to the equivalent diameter of the inner core is greater than 1 and less than or equal to 1.3.

13. The negative electrode sheet according to any one of claims 1-12, wherein the equivalent diameter of the inner core has a value ranging from 10nm to 30um.

14. A battery, comprising: positive pole piece, diaphragm and negative pole piece;

the negative electrode sheet is a negative electrode sheet according to any one of claims 1 to 13, the positive electrode sheet and the negative electrode sheet being separated by the separator.

15. An electronic device, comprising:

An electric device;

the battery of claim 14, the battery being electrically connected with the electrical consumer.

16. The processing method of the negative electrode plate is characterized by comprising the following steps of:

a negative electrode polar material layer is arranged on the surface of the negative electrode current collector; the cathode polar material layer comprises active material particles, the active material particles comprise an inner core and a flexible coating layer, the inner core is wrapped by the flexible coating layer, the inner core comprises silicon-based material particles, and the flexible coating layer comprises a supermolecular polymer.

17. The method for manufacturing a negative electrode sheet according to claim 16, wherein the step of providing a negative electrode polar material layer on the surface of the negative electrode current collector comprises:

heating the first material and the second material in a protective gas atmosphere to enable the first material and the second material to react so as to obtain a supermolecular polymer slurry;

disposing a supramolecular polymer slurry on an outer surface of an inner core to form active material particles having a flexible coating layer;

thoroughly mixing the active material particles and the conductive additive to obtain a polar slurry;

the polar paste is disposed on the surface of the negative electrode current collector to obtain a negative electrode polar material layer.

18. The method for manufacturing a negative electrode sheet according to claim 16, wherein the step of providing a negative electrode polar material layer on the surface of the negative electrode current collector comprises:

disposing a supramolecular polymer slurry on a surface of an inner core to form active material particles having a flexible coating layer;

thoroughly mixing the active material particles, the conductive additive and the solvent to obtain a polar slurry;

the polar slurry is arranged on the surface of the negative electrode current collector;

and drying the polar slurry on the negative electrode current collector to volatilize the solvent in the polar slurry so as to obtain a negative electrode polar material layer.

19. The method of processing a negative electrode sheet according to claim 17 or 18, wherein the first material comprises a polyacid and/or a polyanhydride, the polyanhydride being formed by dehydration of a polyacid; wherein the polyacid comprises one or more of a monomeric fatty acid, a dimeric fatty acid and a trimeric fatty acid;

the second material includes a polyol and/or a polyamine.

20. The method of any one of claims 17-19, wherein disposing a supramolecular polymer slurry on a surface of an inner core to form active material particles having a flexible coating layer, comprises:

Setting the supermolecular polymer slurry on the surface of the inner core to cover the supermolecular polymer slurry on the surface of the inner core;

heating the supramolecular polymer slurry on the surface of the inner core for a second preset time at a second preset temperature;

the supramolecular polymer slurry is cooled to form a flexible coating layer.

21. The method for manufacturing a negative electrode sheet according to claim 20, wherein the second preset temperature has a value ranging from 70 ℃ to 120 ℃; and/or the number of the groups of groups,

the value range of the second preset time is 3-100 min.

22. The method of claim 20 or 21, wherein disposing the supramolecular polymer paste on the surface of the core to cover the supramolecular polymer paste on the surface of the core, comprises:

setting the supermolecular polymer slurry on the surface of the inner core at a third preset temperature so as to cover the supermolecular polymer slurry on the surface of the inner core; wherein the third preset temperature is greater than room temperature and less than the second preset temperature;

the supramolecular polymer slurry is cooled.

23. The method according to any one of claims 17 to 22, wherein when the weight part of the second material is 1 part, the value of the weight part of the second material is in the range of 2 to 10 parts.

24. The method of any one of claims 17 to 23, wherein the conductive additive comprises two forms of additives, a particulate additive and a linear additive; or,