CN115832298A

CN115832298A - Composite electrode material, preparation method thereof, lithium battery and electronic equipment

Info

Publication number: CN115832298A
Application number: CN202111117941.XA
Authority: CN
Inventors: 沙玉静; 夏圣安; 谢封超; 李阳兴
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-09-17
Filing date: 2021-09-17
Publication date: 2023-03-21
Also published as: WO2023041063A1

Abstract

The application discloses a composite electrode material, a preparation method thereof, a lithium battery and electronic equipment. The composite electrode material comprises an electrode material core and a coated organic fiber framework. Wherein, the-CO-NH-or-C = N-contained in the organic fiber can form abundant hydrogen bonds with-OH on the surface of the electrode material core, so that the organic fiber is combined on the surface of the electrode material core in an intertwined manner, and a firm organic fiber framework is formed on the surface of the electrode material core. The high strength characteristic and the small tensile strain of the organic fiber framework can limit the volume expansion of the electrode material, and meanwhile, the organic fiber framework is not easy to generate plastic deformation. Furthermore, the battery circulation stability can be improved, the occupation ratio of the battery in the internal cavity of the electronic equipment is reduced, the available cavity space of key devices such as chips and circuit boards in the electronic equipment is improved, the problems of battery bulge, rear cover tilting and the like after long circulation are avoided, and the service life and the safety of electronic products are improved.

Description

Composite electrode material, preparation method thereof, lithium battery and electronic equipment

Technical Field

The application relates to the technical field of electrode materials, in particular to a composite electrode material, a preparation method of the composite electrode material, a lithium battery and electronic equipment.

Background

Secondary batteries and alkali metal batteries, especially lithium ion batteries in secondary batteries, are gradually becoming mainstream battery technologies in consumer electronics, electric vehicles, electric ships, electric tools, and shared battery replacement markets due to their advantages of high energy utilization efficiency, environmental friendliness, high energy density, and the like. Battery swelling is a common safety failure mode, and for lithium ion batteries, the main factor causing battery swelling is the thickness expansion of battery pole pieces gradually caused in the circulation process. The reasons for causing the thickness expansion of the battery pole piece include crystal expansion caused by the lithium-releasing and lithium-inserting process of the anode and cathode materials, surface SEI instability caused by the crystal expansion, repeated film formation and the like. Therefore, some electrode materials with high capacity characteristics cannot be widely used due to their high expansion rate. For example, silicon with theoretical capacity up to 4200mAh/g is a promising next generation anode material in the art. But the silicon-based anode material expands up to 300%. Therefore, the cycle performance degradation and cell swelling due to the thickness expansion become the biggest challenge for the popularization of silicon cell applications.

In view of the problem of the crystal expansion of the electrode material, many persons skilled in the art limit the crystal expansion of the electrode material by coating the surface of the crystal particles of the electrode material with a carbonaceous material or a ceramic material. However, in the case of the carbonaceous material, if the coating amount is too large, the reversible lithium intercalation and deintercalation efficiency is affected, and since the structural strength thereof is insufficient, the improvement effect on the crystal expansion of the electrode material is small. Although the structural strength of the ceramic material is good for improving the crystal expansion, the ceramic material is easily subjected to plastic deformation, so that when the expansion force or the expansion degree of the crystal is large, the ceramic material layer on the surface of the crystal is broken and loses the effect.

Disclosure of Invention

The application provides a composite electrode material, a preparation method thereof, a lithium battery and electronic equipment, and aims to solve the problem of volume expansion of an electrode.

In a first aspect, the present application provides a composite electrode material, comprising an electrode material core and an organic fiber coating layer with a skeleton structure, wherein the organic fiber coating layer is compounded on the surface of the electrode material core through bonding; the organic fiber contains at least one of-CO-NH-and-C = N-, and a benzene ring structure. Wherein, the organic fiber contains-CO-NH-or-C = N-which can form abundant hydrogen bonds with-OH on the surface of the electrode material core, so that the organic fiber is combined on the surface of the electrode material core in an intertwined manner, thereby forming a firm coating layer with a skeleton structure on the surface of the electrode material core. The high strength characteristic and the small tensile strain of the organic fiber coating layer can limit the volume expansion of the electrode material, and meanwhile, the coating layer is not easy to generate plastic deformation.

In an alternative implementation form of the first aspect, the organic fibres further have-COOH and/or-NH ₂ . Based on-COOH and/or-NH ₂ The organic fiber can form rich hydrogen bonds with-OH on the surface of the inner core of the electrode material, so that the organic fiber is sufficiently and firmly compounded on the surface of the inner core, and the stable function of reducing the volume expansion of the pole piece is realized.

In an alternative implementation manner of the first aspect, the mass proportion of the organic fibers in the composite electrode material is 0.05% -1%. The composite proportion can enable the organic fiber to form a coherent and uniform framework structure on the surface of the electrode material, and ensure the coating effect. In addition, the composite proportion does not cause the change of the crystal structure and phase characteristics of the electrode material crystal particles, thereby ensuring the stable electrochemical performance of the electrode material while limiting the volume expansion of the electrode material. That is, the composite proportion can simultaneously take account of the expansion limiting effect of the organic fiber framework on the electrode material and the surface charge conduction capability of the material.

In an alternative implementation manner of the first aspect, the benzene ring structure is located in the macromolecular chain of the organic fiber, so that a stronger intermolecular conjugation effect is formed, and the organic fiber has higher stability.

In an alternative implementation form of the first aspect, the breaking strength of the organic fibers is greater than 3cN dtex ^-1 The initial modulus of the organic fiber is more than 50cN dtex ^-1 Thereby ensuring the structural strength of the organic fiber and the binding effect on the electrode material.

In an alternative implementation form of the first aspect, the organic fiber coating has a thickness of 10nm to 200nm.

In an alternative implementation of the first aspect, the organic fibers have a diameter of 5nm to 60nm and a length of 1 μm to 20 μm, and the aspect ratio allows for optimal entanglement and encapsulation with a small amount of intermingling.

In an alternative implementation of the first aspect, the organic fiber is an aramid fiber, a polyaradiazole fiber, or a polysulfonamide fiber.

In an alternative implementation manner of the first aspect, the aramid fiber contains aramid chain links of more than 85%, the diameter of the aramid fiber is 5nm-40nm, the length of the aramid fiber is 2 μm-20 μm, and the aspect ratio can form the optimal winding and coating effects in a small compounding amount.

In an alternative implementation form of the first aspect, the composite electrode material comprises composite particles and/or polymeric particles, the composite particles comprise an electrode material core and an organic fiber coating layer compounded on the surface of the electrode material core through bonding, and the polymeric particles are formed by polymerization of the composite particles.

Optionally, the composite particles include primary composite particles and secondary composite particles, wherein the inner core of the primary composite particles is an electrode material inner core, and the inner core of the secondary composite particles is a polymeric particle formed by polymerizing the primary composite particles. That is, the particles constituting the composite electrode material may be one or more of primary composite particles, secondary composite particles, and polymeric particles of the primary composite particles and/or the secondary composite particles. Because the particle structures and particle sizes of the primary composite particles, the secondary composite particles and the polymeric particles thereof are different, when the composite electrode material contains various particles, the various particles compensate each other in performance, and the particle size distribution of the composite electrode material can be adjusted by adjusting the content of each particle, so that the compaction density of the composite electrode material is adjusted.

In an alternative implementation form of the first aspect, the composite electrode material further comprises a conductive agent and/or an ionic conductor. The addition of the conductive agent and/or the ionic conductor can compensate the problem of the reduction of the conductive capacity of the composite electrode material caused by the non-conductivity of the organic fiber, thereby ensuring the surface charge conductive capacity of the composite electrode material.

In an alternative implementation of the first aspect, the conductive agent and/or the ionic conductor is coated on the surface of the composite particles and/or the polymeric particles or mixed between the composite particles and/or the polymeric particles.

In an alternative implementation manner of the first aspect, the conductive agent includes one or more of amorphous carbon, soft carbon, hard carbon, graphite, carbon nanotube, graphene, and metal particle.

In an alternative implementation manner of the first aspect, the electrode material comprises a ternary cathode material, a silicon-based, tin-based, sulfur-based, and metallic lithium cathode material.

In a second aspect, the present application also provides a method for preparing a composite electrode material, the method comprising: preparing an organic fiber solution, wherein the organic fiber contains at least one of-CO-NH-and-C = N-and a benzene ring structure; adding an electrode material into the organic fiber solution according to a preset composite proportion, and stirring until the electrode material is uniformly dispersed; and drying the mixed solution of the electrode material and the organic fiber to obtain the composite electrode material. The composite electrode material comprises an electrode material core and an organic fiber coating layer with a skeleton structure, wherein the organic fiber coating layer is compounded on the surface of the electrode material core through bonding. Wherein, the organic fiber contains-CO-NH-or-C = N-which can form abundant hydrogen bonds with-OH on the surface of the electrode material core, so that the organic fiber is combined on the surface of the electrode material core in an intertwined manner, thereby forming a firm coating layer with a skeleton structure on the surface of the electrode material core. The high strength characteristic and the small tensile strain of the organic fiber coating layer can limit the volume expansion of the electrode material, and meanwhile, the coating layer is not easy to generate plastic deformation.

In a third aspect, the application also provides a composite electrode material, which is prepared by the preparation method of the second aspect.

In a fourth aspect, the application also provides an application of the composite electrode material in the field of preparation of lithium batteries.

In a fifth aspect, the present application further provides a lithium battery, including a positive electrode material, an electrolyte, a separator, and a negative electrode material, where the positive electrode material or the negative electrode material is the composite electrode material described in any one of the implementation manners of the first aspect.

The sixth aspect, this application still provides an electronic equipment, including charge and discharge circuit and with the electric element, still include the fifth aspect the lithium cell, the lithium cell is connected with charge and discharge circuit, charges or for supplying power with the electric element through charge and discharge circuit.

By the composite electrode material and the preparation method thereof, a lithium battery comprising the composite electrode material and an electronic device comprising the lithium battery can be obtained. The composite electrode material comprises an electrode material core and an organic fiber coating layer with a skeleton structure, wherein the organic fiber coating layer is compounded on the surface of the electrode material core through bonding. Wherein, the organic fiber contains-CO-NH-or-C = N-which can form abundant hydrogen bonds with-OH on the surface of the electrode material core, so that the organic fiber is combined on the surface of the electrode material core in an intertwined manner, thereby forming a firm coating layer with a skeleton structure on the surface of the electrode material core. The high strength characteristic and the small tensile strain of the organic fiber coating layer can limit the volume expansion of the electrode material, and meanwhile, the coating layer is not easy to generate plastic deformation. Furthermore, the battery circulation stability can be improved, the occupation ratio of the battery in the internal cavity of the electronic equipment is reduced, the available cavity space of key devices such as chips and circuit boards in the electronic equipment is improved, the problems of battery bulge, rear cover tilting and the like after long circulation are avoided, and the service life and the safety of electronic products are improved.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.

Fig. 1 is a schematic diagram of a lithium ion battery structure exemplarily shown in the present application;

fig. 2 is a schematic structural diagram of a composite electrode material of a lithium ion battery provided in an embodiment of the present application;

fig. 3 is a schematic structural diagram of a composite electrode material of a lithium ion battery provided in an embodiment of the present application;

fig. 4 is a schematic structural diagram of a composite electrode material of a lithium ion battery provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of a composite electrode material of a lithium ion battery provided in an embodiment of the present application;

FIG. 6 is a stress-strain curve of aramid, polysulfonamide and polyaryl oxadiazole, styrene-butadiene rubber and polyacrylic acid provided in an example of the present application;

FIG. 7 is a flow chart of a method for preparing a composite electrode material according to an embodiment of the present disclosure;

FIG. 8 is a diagram of an aramid nanofiber composite silica micromirror made in example 2;

fig. 9 is an electron microscope image of the secondary composite particles of polysulfonamide nanofibers and silica prepared in example 5.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Fig. 1 is a schematic diagram of a lithium ion battery structure exemplarily shown in the present application. The lithium ion battery comprises a positive electrode, a negative electrode, electrolyte, a diaphragm, a corresponding loop and the like. The positive/negative electrode material can release lithium ions to realize energy storage and release, the electrolyte is a carrier for lithium ions to be transmitted between the positive/negative electrodes, and the non-conductive diaphragm can be permeable to the lithium ions and separates the positive/negative electrodes to prevent short circuit. The positive/negative electrode material is a main part playing a role of energy storage, and is the most direct embodiment of the energy density, the cycle performance and the safety performance of the battery cell.

In one implementation, in the lithium ion battery, the positive electrode may include an aluminum electrode plate and a positive electrode material including, for example, a ternary positive electrode material lithium nickel cobalt manganese oxide LiNixCoyMnzO ₂ Wherein, the proportion (x: y: z) of nickel, cobalt and manganese can be adjusted according to actual needs.

In one implementation, in the lithium ion battery, the negative electrode may include a copper electrode plate and a negative electrode material, and the negative electrode material includes a carbon material, a silicon-based material, a tin-based material, a sulfur-based material, a metal lithium, and the like.

For example, when a lithium ion battery is charged, lithium ions are extracted from crystal lattices of a positive electrode material, and are inserted into a negative electrode material after passing through an electrolyte, so that the negative electrode is rich in lithium and the positive electrode is poor in lithium; when the lithium ion battery discharges, lithium ions are extracted from the negative electrode material and are inserted into the crystal lattice of the positive electrode material after passing through the electrolyte, so that the positive electrode is rich in lithium and the negative electrode is poor in lithium. Thus, the difference of the potentials of the positive and negative electrode materials relative to the metallic lithium during the process of inserting and extracting lithium ions is the working voltage of the battery.

For convenience of description, in the following examples, the positive electrode material and the negative electrode material are collectively referred to as electrode materials. That is, unless otherwise specified, the electrode material in the following examples refers to a positive electrode material and/or a negative electrode material, and the composite electrode material refers to a composite positive electrode material and/or a composite negative electrode material.

With the increasing requirements of electronic products on energy density and quick charging capability of batteries, safety accidents of lithium ion batteries frequently occur, and thus, the safety accidents cause extensive worry of markets and users. Soft pack lithium ion battery swelling is a common safety failure mode for certain electronic products. The increase of the thickness of the electrode pole piece caused by the volume expansion of the electrode material crystal particles in the cyclic charge-discharge process is a common cause of battery swelling.

Therefore, some electrode materials with high capacity characteristics cannot be widely used due to their high expansion rate. Taking silicon-based anode materials as an example, the theoretical capacity of silicon is up to 4200mAh/g, which is expected to be the next generation anode material in the field. However, crystalline silicon undergoes Si-Si bond breakage during charging to produce a lithium silicon alloy, a process that is accompanied by a large volume expansion. For the material body, a large amount of shear stress is generated by volume expansion, so that silicon particles are cracked, the internal resistance is increased, and the direct transmission of electrons on the electrode is influenced; the stress caused by the volume expansion causes the destruction of the electrode structure including the exfoliation of the active material, the peeling from the binder and the conductive network, and the like, for the entire electrode, thereby causing capacity fade. Meanwhile, the volume expansion can cause instability of SEI on the silicon surface, and then the SEI is repeatedly cracked and continuously generates a new SEI film with the electrolyte, a large amount of lithium ions are consumed, the SEI is gradually thickened, electron transfer and lithium ion diffusion are hindered, and impedance and polarization are increased. In addition, volume expansion can cause fusion of originally dispersed silicon particles after lithium intercalation, so that the size of local silicon particles is increased, and later cycle and stress release are not facilitated. It can be seen that the degradation of the cycling performance of the battery and the swelling of the battery due to the volume expansion of the silicon-based negative electrode material become the biggest challenges for the wide application of silicon-based materials.

Aiming at the problem of volume expansion of an electrode material, the embodiment of the application provides a composite electrode material and a preparation method thereof. The composite electrode material is an active material of a lithium ion battery and is used for manufacturing an electrode. The composite electrode material takes the electrode material as a core body material, and the volume expansion of the core body material can be effectively limited through the organic fiber framework structure coated on the outer layer of the core body material.

Fig. 2 to fig. 5 are schematic structural diagrams of a composite electrode material of a lithium ion battery provided in an embodiment of the present application.

Referring to fig. 2, in some embodiments, the composite electrode material includes: an electrode material core 201 and an organic fiber coating layer 202 with a skeleton structure, wherein the organic fiber coating layer 202 is composed of organic fibers, and the organic fibers are compounded on the surface of the electrode material core 201 through bonding. In other words, the organic fibers are bonded and wound with each other and simultaneously coated on the surface of the electrode material core 201, and an organic fiber skeleton is formed on the surface of the electrode material core 201. The high strength characteristic and the smaller tensile strain of the organic fiber framework can limit the volume expansion of the electrode material, and meanwhile, the organic fiber framework is not easy to generate plastic deformation.

In the present application, the bonding between the organic fiber and the core of the electrode material is not limited to chemical bonds such as metal bonds, ionic bonds, and covalent bonds, but also refers to hydrogen bonding. Wherein the molecular structure of the organic fiber contains at least one of-CO-NH-and-C = N-and a benzene ring structure. The benzene ring structure is positioned in a macromolecular chain of the organic fiber, so that a stronger intermolecular conjugation effect is formed, the conjugation effect provides acting force for mutual adhesion and winding between the organic fibers, and the structural strength and the stability of the skeleton structure are further ensured. And the-CO-NH-or-C = N-can form abundant hydrogen bonds with-OH on the surface of the electrode material core, and the hydrogen bonds provide binding force between the organic fibers and the electrode material core, so that the organic fibers are firmly compounded on the surface of the electrode material core.

In certain embodiments, the organic fibers may also contain-COOH and/or-NH ₂ . Based on-COOH and/or-NH ₂ The organic fiber can form abundant hydrogen bonds with-OH on the surface of the core body material, so that the organic fiber is firmly and sufficiently compounded on the surface of the core body material, thereby playing a stable role in reducing the volume expansion of the core body material.

The organic fiber coating layer is not limited to being combined on the inner surface of the electrode material by hydrogen bonding. For example, in some embodiments, groups capable of forming stable chemical bonds with the electrode material may be grafted onto the chain structures of the organic fibers by a specific chemical treatment method, so that the organic fibers may be compounded on the surface of the electrode material core through chemical bonding.

It is worth noting that the mass ratio of the organic fibers in the composite electrode material is a key factor influencing the strength of the framework structure and the coating effect, and further influencing the limiting effect on the volume expansion of the core body material. Specifically, when the composite proportion is too low, the skeleton structure formed by the organic fibers is not coherent enough, the gap is too large, a coherent coating effect cannot be formed on the surface of the core body material, and the limiting capability on the expansion of the core body material is insufficient; when the compounding ratio is too high, the conductivity of the organic fiber is poor, so that the surface charge conductivity of the core body material is reduced, and the rate performance is influenced.

In certain embodiments, the organic fiber is present in the composite electrode material in an amount of 0.05% to 1% by weight. The composite proportion can enable the organic fiber to form a coherent and uniform framework structure on the surface of the core body material, and ensure the coating effect. In addition, the composite proportion can not cause the change of the crystal structure and the phase characteristics of the crystal particles of the core body material, thereby ensuring the stable electrochemical performance of the electrode material while limiting the volume expansion of the electrode material. That is, the composite ratio can combine the restriction effect of the organic fiber skeleton on the expansion of the core body material and the surface charge conduction capability of the material.

In certain embodiments, the organic fibers have a breaking strength greater than 3cN dtex ^-1 The initial modulus of the organic fiber is more than 50cN dtex ^-1 Thereby ensuring the structural strength of the organic fiber and the binding effect on the electrode material.

In certain embodiments, the organic fibers have a diameter of 5nm to 60nm and a length of 1 μm to 20 μm. Alternatively, the organic fibers have an aspect ratio greater than 30. The appropriate aspect ratio can provide the best winding and coating effect with less compound amount.

In some embodiments, the organic fiber coating has a thickness of 10nm to 200nm.

As an example, the organic fiber skeleton is made of aramid fiber. The aramid fiber is an aromatic polyamide fiber, and mainly comprises Poly-p-phenylene diamine terephthalamide (PPTA) fiber, which is hereinafter referred to as para-aramid fiber, poly-metaphenylene isophthalamide (MPIA) fiber, and is hereinafter referred to as meta-aramid fiber. The molecular structural formula of the meta-aramid fiber is shown as the following formula (1), and the molecular structural formula of the para-aramid fiber is shown as the following formula (2):

in some implementations, the aramid fiber has a diameter of 5nm to 40nm and a length of 2 μm to 20 μm, and with an appropriate aspect ratio, optimal entanglement and coating effects can be achieved with a small amount of compounding.

As an example, the organic fiber skeleton is made of a polyaryloxadiazole fiber. Polyaryl oxadiazole fibers (POD for short). In the molecular structure, a main chain contains a benzene ring and an oxadiazole ring, a chain segment contains aromatic groups, and a macromolecular chain is in a rigid rod-like structure. The molecular structural formula is shown as the following formula (3):

as an example, the organic fiber skeleton is made of polysulfonamide fibers. Polysulfonamide fibers (PSA) which are Polysulfonamide fibers are polymers containing sulfone groups (-SO) in the main polymer chain ₂ -) having the chemical name terephthaloyl-3, 3-4, 4-diaminodiphenyl sulfone fiber. The fiber-forming high polymer polysulfonamide is formed by condensation polymerization of paraphthaloyl chloride, 4 '-diaminodiphenylalum (4, 4' -DDS) and 3,3 '-diaminodiphenylsulfone (3, 3' -DDS), and is a linear macromolecule formed by mutually connecting para-phenyl and meta-phenyl by amide groups and sulfone groups, and the molecular structure of the linear macromolecule is shown as the following formula (4).

In some embodiments, the organic fiber polymer used for preparing the composite electrode material has a film-forming tensile stress greater than 5MPa and a tensile strain less than 50% to ensure that the organic fiber skeleton formed on the surface of the core body material has high strength characteristics and low tensile strain characteristics, so that the organic fiber polymer can effectively limit the volume expansion of the electrode material and simultaneously ensure that the organic fiber skeleton is not easy to generate plastic deformation.

Illustratively, the organic polymer which can be used for preparing the composite electrode material can be selected by testing the film-forming tensile stress and tensile strain of various organic polymers. For example, film forming performance tests were performed on aramid, polysulfonamide, and polyaryl oxadiazole, styrene butadiene rubber, and polyacrylic acid. Specifically, firstly, respectively preparing aramid fiber slurry, polysulfonamide slurry, polyaryl oxadiazole slurry, styrene butadiene rubber slurry and polyacrylic acid slurry; then according to the preset solid content, taking a proper amount of the slurry, respectively injecting the slurry into a polytetrafluoroethylene mold frame, and air-drying at room temperature to form a film; cutting the formed film into sample strips with the thickness of 30mm multiplied by 3mm, and testing the tensile property of the sample by adopting a DMA-800 instrument of TA company, wherein the testing conditions specifically comprise a testing mode: control force mode (DMA Controlled force), test target: stress-Strain (Stress-Strain), clamp: stretched Film (Tensile Film), preload force: 0.1N, constant temperature: 25 ℃, standing time: 1min, lift rate: 1N/min; the stress-strain curve shown in fig. 6 was obtained by the test. The stress-strain curve of the film formed by the styrene butadiene rubber is A, the stress-strain curve of the film formed by the polyacrylic acid is B, the stress-strain curve of the film formed by the polysulfonamide is C, the stress-strain curve of the film formed by the aramid fiber is D, and the stress-strain curve of the film formed by the polyaryl oxadiazole is E.

It can be seen that the film-forming tensile stress of the aramid fiber, the polysulfonamide and the polyaryl oxadiazole is more than 5MPa, the tensile strain is less than 50%, the film-forming tensile stress of the styrene butadiene rubber is less than 5MPa, the tensile strain is more than 500%, the film-forming tensile stress of the polyacrylic acid is more than 5MPa, and the tensile strain is more than 300%.

In the present application, the organic fiber skeleton compounded on the surface of the core body material is formed by intertwining high-strength nanofibers. Based on the high strength characteristic of the organic fiber framework, the volume expansion of the electrode material can be effectively limited. It is noted that some solutions for coating with organic polymers to limit swelling utilize the elasticity and toughness of the polymer coating, without considering the strength of the polymer coating. Unlike the stiffness-limiting effect of the organic fibrous matrix described herein, such polymeric coating acts like a "gummy candy". In addition, since the structure of such a polymer coating layer is different from that of the organic fiber skeleton in the present application, the principle and effect of restricting the expansion of the core body material are also different.

In certain embodiments, the host particles of the composite electrode material comprise composite particles and/or polymeric particles. Composite particles are meant to be based on a core having an organic fiber coating on the surface thereof. It will be appreciated that the particle structure of composite particles based on different nuclei will be different, as may be seen in particular in figures 2 to 5. The polymer particles refer to a composite particle cluster in which one or more types of composite particles are agglomerated.

Fig. 2 schematically shows an example of the composite particle. As shown in fig. 2, the composite particle 200 may include an electrode material core 201 and an organic fiber skeleton 202 composited on a surface of the electrode material core 201. For convenience of explanation, the composite particles having the electrode material crystal particles as the core and the organic fiber skeleton as shown in fig. 2 may be referred to as primary composite particles.

Fig. 3 schematically shows another example of the composite particle. As shown in fig. 3, the composite particle 300 may include a core body 301 in which a plurality of electrode material cores 201 are agglomerated and an organic fiber skeleton 302 compounded on an outer surface of the core body 301.

It is to be understood that the composite particles may also include a composite particle group in which a plurality of primary composite particles are agglomerated and an organic fiber skeleton compounded on the outer surface of the composite particle group. For convenience of explanation, the composite particles having the core particle group and/or the composite particle group as an inner core and coating the organic fiber skeleton as described above may be referred to as secondary composite particles.

Fig. 4 schematically shows an example of the polymeric particles. As shown in fig. 4, the polymeric particles 400 are agglomerated from the primary composite particles 200.

Fig. 5 schematically shows an example of the polymeric particle. As shown in fig. 5, the polymer particles 500 are agglomerated from the secondary composite particles 300.

It should be noted that the structure of the polymeric particles provided herein includes, but is not limited to, the structure shown in fig. 4 and 5. For example, the polymeric particles may also be polymerized from primary composite particles and secondary composite particles.

In other words, the host particles constituting the composite electrode material may be one or more of primary composite particles, secondary composite particles, and polymeric particles of the primary composite particles and/or the secondary composite particles. Because the particle structures and particle sizes of the primary composite particles, the secondary composite particles and the polymeric particles thereof are different, when the composite electrode material contains various particles, the various particles compensate each other in performance, and the particle size distribution of the composite electrode material can be adjusted by adjusting the content of each particle, so that the compaction density of the composite electrode material is adjusted.

It is to be understood that the secondary composite particles and the polymeric particles may be obtained by granulation. Wherein the core body may be obtained by bonding a plurality of core bodies. In other words, the core body may be formed by aggregating a plurality of core bodies, and the particle body may refer to a particle obtained after binding of particles having an organic fiber skeleton. Exemplary ways of obtaining the secondary composite particles and the polymeric particles may be, for example: forming a core body group or a particle group by controlling the temperature of the core body material particles or the composite particles so that the core body material particles and the composite particles form a core body group or a particle group through the cohesiveness of the core body material particles and the composite particles; alternatively, the core material particles and the composite particles may be rendered cohesive by the addition of a binder to form a core mass or a particle mass. The method of obtaining the secondary particles by granulation is not limited to this, and the present application does not limit this.

In certain embodiments, the composite electrode material further comprises a conductive agent. The addition of the conductive agent can compensate the problem of the reduction of the conductive capability of the composite electrode material caused by the non-conductivity of the organic fiber, thereby ensuring the surface charge conductive capability of the composite electrode material. The conductive agent includes, but is not limited to, amorphous carbon, soft carbon, hard carbon, graphite, carbon nanotubes, graphene, a combination of one or more of metal particles.

In certain embodiments, the composite electrode material further comprises an ionic conductor. The addition of the ion conductor can improve the lithium ion diffusion capability of the composite electrode material. The ion conductor includes, but is not limited to, oxide, sulfide, and other solid electrolytes, and materials having multi-dimensional lithium ion channels.

In alternative implementations, the conductive agent and/or ionic conductor is coated on the surface of the composite particles and/or polymeric particles or mixed between the composite particles and/or polymeric particles.

In some embodiments, the electrode material, i.e., the core material, used to prepare the composite electrode material described above may be either a positive electrode material or a negative electrode material. Wherein the positive electrode material may be a ternary material. The negative electrode material can be silicon-based, tin-based, sulfur-based, metal lithium and other materials, such as silicon, nano silicon, micron silicon, silicon oxide, silicon sub-oxide (SiOx, 0< x < 2), silicon carbon (Si/C), porous silicon, thin-film silicon, tin dioxide, silicon-tin alloy, lithium-silicon alloy, lithium-phosphorus alloy, lithium titanate and the like.

It should be understood that the negative electrode material and the positive electrode material of the lithium ion battery listed above are merely exemplary examples, and may further include other various materials, which are not limited in the embodiments of the present application.

The following describes a method for preparing the composite electrode material provided in the embodiments of the present application. Fig. 7 shows a flowchart of a method for preparing a composite electrode material provided in an embodiment of the present application. As shown in fig. 7, the following steps may be included:

s701, preparing an organic fiber solution, wherein the molecular structure of the organic fiber contains at least one of-CO-NH-and-C = N-and a benzene ring structure.

In some embodiments, a nano-scale organic fiber solution is prepared by S701, and hereinafter referred to as a nanofiber solution for convenience of description.

Wherein, the precursor of the organic fiber molecule can be used as the initial raw material to prepare the organic nano fiber solution. The precursor is referred to herein on the premise that organic fiber molecules are targeted. In other words, the precursor of the organic fiber molecules is in the form of existence before the organic fiber molecules are obtained. Taking the aramid fiber as an example, in the example of preparing the aramid fiber by using p-phenylenediamine and terephthaloyl chloride, the p-phenylenediamine and the terephthaloyl chloride are precursors. Or preparing the nano-fiber solution by using the fiber-forming high polymer as a starting material. Here, the fibril fibers, which are fiber-forming polymers, refer to fibers of large size relative to nanofibers. For example, large size aramid fibers can be used to make aramid nanofibers.

Specifically, methods of preparing the nanofiber solution include, but are not limited to: polymerization induced self-assembly, electrospinning, mechanical disintegration, and deprotonation. Wherein:

the polymerization-induced self-assembly refers to a method for directly preparing the polymer nano-fiber by utilizing monomer polymerization. Taking aramid fiber as an example, in the traditional polymerization process, PPTA molecular chains are aggregated along with the growth of the chains, and high molecular weight aramid fiber is formed. In order to obtain the aramid nano-fiber instead of the large-size aramid fiber, an inducer such as methoxypolyethylene glycol or polyethylene glycol dimethyl ether is required to be added in the synthesis process. The inducer has the functions of adjusting the chain direction by forming hydrogen bonds with the aramid nano-fiber monomers, inhibiting irregular aggregation of the aramid nano-fiber monomer molecular chains caused by free assembly of the hydrogen bonds and promoting the formation of a stable aramid nano-fiber solution. However, it should be noted that the self-assembly method is difficult to control the degree of polymerization, and often needs to introduce some inert groups to control the reaction speed and degree, so that it is difficult to control the size of the finally obtained nanofibers.

In the process of preparing the fiber by electrostatic spinning, strong acid or strong base is used for dissolving the fiber to obtain an electrospinning stock solution, and the obtained solution is subjected to jet spinning in a strong electric field. Under the action of the electric field, the liquid drop at the needle head changes from a spherical shape to a conical shape (i.e. a Taylor cone) and extends from the tip of the cone to obtain a fiber filament. The conductivity of the electrospinning stock solution is higher or the solution viscosity is not matched because strong acid or strong base is needed to dissolve the fibers, so that the filament discharging difficulty is increased.

The mechanical disintegration method is based on that the molecular chain of the fiber has strong atom bonds along the axial direction and weak molecular bonds along the radial direction, so that the fiber has obvious strength anisotropy, and the epidermal layer of the fiber is easy to peel off along the fiber axis under the action of mechanical fibrillation. Wherein, fiber molecules can be subjected to hydrolysis pretreatment through an acid/alkali solution to assist mechanical force disintegration, and ion charges on the fiber surface are changed in combination with alkane hydrolysis treatment, so that a nano-scale fiber solution is finally prepared.

The principle of the deprotonation method is that fibers are placed in a strong base DMSO solution, negative charges are gradually gathered on fiber molecular chains, electrostatic repulsion is generated, and the fibers on the top are split into PPTA microfibers with the average size of 1-2 micrometers. With the increase of the deprotonation effect, the electrostatic repulsion force between the polymer chains is stronger and stronger, so that the required energy is provided for breaking the hydrogen bonds between the polymer chains, and finally the nanofiber with high width-to-length ratio is obtained. The nanofibers can be stably dispersed under the balance of electrostatic repulsion, van der waals forces, and pi-pi stacking.

S702, adding the core body material into the organic fiber solution, and uniformly dispersing.

The core body material, namely the electrode material without surface treatment, can be a positive electrode material and can also be a negative electrode material. The positive electrode material includes, but is not limited to, ternary materials, such as NCM811. Anode materials include, but are not limited to, silicon based, tin based, sulfur based, lithium metal, and the like. It will be appreciated that the core material employed will generally be an electrode material which expands significantly in volume.

And S703, drying the mixed solution of the core body material and the organic fibers to obtain the composite electrode material.

Wherein, can adopt freeze drying, spray drying, hot air drying's mode to carry out drying process to the mixed liquid of core body material and organic fiber to can adjust the drying parameter as required.

It is to be noted that, when the drying treatment is performed, an inert gas atmosphere is not required, and heat treatment (semi-carbonization) is not required, thereby ensuring the strength of the clad layer.

The preparation method of the composite electrode material is described in the following by specific examples, and the lithium ion battery is prepared by using the composite electrode material sample prepared in the examples, and the performance of the lithium ion battery and the expansion condition of the pole piece are tested.

Example 1

The aramid nano-fiber (ANFs) composite ternary cathode material (NCM 811) is prepared, the composite proportion is 0.05%, hereinafter referred to as 'ANFs-NCM 811-0.05', and the specific implementation steps are as follows.

And S110, preparing an aramid nanofiber solution. The method specifically comprises the following steps:

s111, 100mL of N-methylpyrrolidone was added to the reaction vessel and heated to 100 ℃ under a nitrogen atmosphere.

S112, stirring for 5min at the temperature of 100 ℃.

S113, adding CaCl ₂ And dimethyl ether, and dissolved at 100 ℃ for 30min with stirring.

S114, cooling to 0 ℃, adding p-phenylenediamine, and stirring until the p-phenylenediamine is completely dissolved.

In the above step, the stirring speed may be controlled at 400 rpm.

And S115, adding terephthaloyl chloride, stirring and starting the reaction. Wherein, the stirring speed can be controlled at 2000 rpm.

In the reaction system, the concentrations of the terephthaloyl chloride and the p-phenylenediamine are 0.21 mol/L and 0.20mol/L respectively, and the methyl ether accounts for 3wt% of the total weight of the terephthaloyl chloride and the p-phenylenediamine.

And S116, after the reaction is stopped, diluting the reaction product by using N-methyl pyrrolidone, and adding a certain amount of deionized water.

And S117, homogenizing the diluted product in a high-shear homogenizer to obtain the aramid nano-fiber solution with the concentration of 0.1%. Wherein the homogenizer speed is 10000rpm, and the homogenizing time is 5min

S120, adding an NCM811 material into the aramid nanofiber solution, and stirring and dispersing uniformly at a low speed, wherein the mass ratio of the NCM811 material to the aramid nanofiber is 0.05.

S130, transferring the mixed solution of the NCM811 material and the aramid nano-fibers into a freeze dryer, freeze-drying at the temperature of about-60 ℃, and collecting a product, namely the aramid nano-fibers (ANFs) composite polycrystalline ternary positive electrode material (NCM 811).

Example 2

The preparation method comprises the following steps of preparing aramid nano-fiber (ANFs) composite silica with the composite proportion of 0.1 percent, and the composite proportion is hereinafter referred to as 'ANFs-SiO-0.1', and specifically implementing the steps as follows.

S210, preparing an aramid nanofiber solution. The method specifically comprises the following steps:

s211, a mixture of 0.5g of poly (p-phenylene terephthalamide) and 1.0g of KOH is added to 300mL of dimethyl sulfoxide and magnetically stirred at room temperature for 7 days to obtain a uniform and transparent ANF/DMSO solution.

S212, diluting the reaction product by using dimethyl sulfoxide, and diluting the concentration of ANF to 0.05%.

S220, adding 500g of silica powder into the ANF/DMSO solution with the ANF concentration of 0.05%, stirring uniformly, transferring to a mixing machine, and shaking at 1200rpm for 15min.

And S230, placing the mixed solution of the silicon monoxide and the ANF/DMSO into a freeze dryer, and freeze-drying at the temperature of about-60 ℃.

S240, the lyophilized product is added to ethanol containing a trace amount of water. And S240, the ANF is protonated again at a slower speed, the connection between partial nano fibers is repaired, and the strength of the aramid nano fibers and the adhesion effect of the aramid nano fibers on the silicon oxide particles are ensured.

And S250, placing the solution in the S240 in a freeze dryer, freeze-drying at the temperature of about-60 ℃, and collecting a product, namely the aramid nano-fiber (ANFs) composite silica.

Fig. 8 is a diagram of an aramid nanofiber composite silica micromirror prepared in example 2.

Example 3

The aramid nano-fiber (ANFs) composite silicon oxide is prepared, the composite proportion is 0.5 percent, hereinafter referred to as 'ANFs-SiO-0.5', and the specific implementation steps are as follows.

And S310, preparing an aramid nanofiber solution. The method specifically comprises the following steps:

s311, a mixture of 0.5g of poly (p-phenylene terephthalamide) and 1.0g KOH was added to 300mL of dimethyl sulfoxide and magnetically stirred at room temperature for 7 days to obtain a uniform and transparent ANF/DMSO solution.

S312, diluting the reaction product by using dimethyl sulfoxide, and diluting the concentration of ANF to 0.05%.

S320, adding 100g of silicon monoxide powder into the ANF/DMSO solution with the ANF concentration of 0.05%, uniformly stirring, transferring to a mixing machine, and shaking at 1200rpm for 15min.

S330, placing the mixture of the silicon monoxide and the ANF/DMSO in a freeze dryer, and freeze-drying at the temperature of about-60 ℃.

S340, adding the lyophilized product to ethanol containing a trace amount of water. Through S340, the ANF is protonated again at a slower speed, the connection between partial nano fibers is repaired, and the strength of the aramid nano fibers and the adhesion effect of the aramid nano fibers on the silicon oxide particles are ensured.

And S350, placing the solution in the S340 into a freeze dryer, freeze-drying at the temperature of about-60 ℃, and collecting a product, namely the aramid nano-fiber composite silica.

Example 4

The preparation method comprises the following specific steps of preparing aramid nano-fiber (ANFs) composite silicon oxide with the composite proportion of 1 percent, and the composite proportion is hereinafter referred to as 'ANFs-SiO-1'.

And S410, preparing an aramid nanofiber solution. The method specifically comprises the following steps:

s411, a mixture of 0.5g of poly (p-phenylene terephthalamide) and 1.0g KOH was added to 300mL of dimethyl sulfoxide and magnetically stirred at room temperature for 7 days to obtain a uniform and transparent ANF/DMSO solution.

And S412, diluting the reaction product by using dimethyl sulfoxide, and diluting the concentration of ANF to 0.05%.

S420, adding 50g of silica powder into the ANF/DMSO solution with the ANF concentration of 0.05%, stirring uniformly, transferring to a mixing machine, and shaking at 1200rpm for 15min.

S430, placing the mixture of the silicon monoxide and the ANF/DMSO in a freeze dryer, and freeze-drying at the temperature of about-60 ℃.

S440, the lyophilized product is added to ethanol containing a trace amount of water. Through S340, the ANF is protonated again at a slower speed, the connection between partial nano fibers is repaired, and the strength of the aramid nano fibers and the adhesion effect of the aramid nano fibers on the silicon oxide particles are ensured.

And S450, placing the solution in the S440 into a freeze dryer, freeze-drying at the temperature of about-60 ℃, and collecting a product, namely the aramid nano-fiber composite silica.

Example 5

The polysulfonamide nanofiber (PSA) composite silicon oxide secondary composite particles are prepared, the composite proportion is 0.5 percent, the PSA-SiO-agg-0.5 percent is used for short, and the specific implementation steps are as follows.

S510, preparing an polysulfonamide nanofiber solution. The method specifically comprises the following steps:

and S511, adding the fibril PSA fiber and KOH into an N-methylpyrrolidone solution according to the mass ratio of 1.

S512, placing the stirred solution into an ultrasonic cell crusher, and carrying out ultrasonic stripping treatment on the polysulfonamide fibers in the solution under the condition of 18kHz-21kHz to obtain a polysulfonamide nanofiber solution.

S520, preparing a mixed solution of the silicon oxide and the polysulfonamide nano fibers.

S521, adding the silica powder with the D50 of 5 mu m into an ethanol solution to obtain silica slurry; the silica slurry was subjected to a sanding treatment using zirconia balls having a diameter of 3 mm. Wherein, the ball-material ratio is 10, the rotating speed is 3000rpm, and the sanding time is 30min. By sanding the silica powder in S521, the D50 of the silica powder can be reduced to 1 μm or less, and the particle size distribution of the silica can be made more uniform.

S522, uniformly mixing the sanded silicon oxide slurry and the polysulfonamide nanofiber solution according to the compounding ratio of 0.5%.

S530, transferring the mixed solution of the silicon oxide and the polysulfonamide nano fibers into a closed spray drying container, and carrying out spray drying treatment on the mixed solution under the conditions that the speed of a centrifugal atomizing disk is 15000rpm, the atomizing temperature is 150 ℃ and the drying medium is N2 to obtain secondary composite particles of the polysulfonamide nano fibers and the silicon oxide.

Example 6

The polyaryl oxadiazole nanofiber (POD) composite silicon carbon (Si/C) is prepared, the composite proportion is 1 percent, hereinafter referred to as POD-Si/C-1, and the specific implementation steps are as follows.

S610, preparing a polyaryl oxadiazole nanofiber solution. The method specifically comprises the following steps:

s611, adding fibril POD fibers and KOH into 300ml of N-methylpyrrolidone solution according to the mass ratio of 1.

Because the conjugation of the benzene ring and the heterocyclic ring in POD is strong, only partial deprotonation can be achieved to form the nanofiber after the POD is subjected to strong alkali DMSO environment and stirred for 7 days.

And S612, pouring the POD/DMSO suspension into a centrifuge tube, performing centrifugal separation for 15min at 10000rpm, and taking an upper transparent solution part to obtain a POD nanofiber/DMSO dispersion.

And S620, adding silicon carbon (Si/C) powder into the POD nanofiber/DMSO dispersion liquid according to the compounding ratio, and stirring for 6 hours at the rotating speed of 300 rpm.

S630, placing the mixed solution of silicon carbon (Si/C) powder and POD nano fibers in a blast drying oven, completely drying at 60 ℃, and collecting the product to obtain the polyaryl oxadiazole nano fiber (POD) composite silicon carbon (Si/C).

Comparative example 1

The silicon monoxide material without surface treatment is used as the anode material in the comparative example I, and is referred to as SiO blank in the following.

Comparative example 2

The Polyurethane (PUR) composite silicon monoxide negative electrode material is prepared, the composite proportion is 0.1 percent, and the PUR-SiO-0.1 percent is abbreviated as follows.

The preparation method comprises the following specific steps: weighing 1g of polyurethane, dissolving in water, and stirring until the polyurethane is completely dissolved; weighing 1000g of SiO, adding the weighed 1000g of SiO into a polyurethane solution, and stirring to obtain mixed slurry; transferring the mixed slurry to a spray dryer, and introducing N ₂ Spray drying at 130 deg.C to obtain Polyurethane (PUR) composite silica powder.

Comparative example 3

Preparing Polyaniline (PANI) composite silicon oxide negative electrode material, wherein the composite proportion is 0.5 percent, and the composite proportion is abbreviated as PANI-SiO-0.5 in the following.

The preparation method comprises the following specific steps: weighing 1g of polyaniline, dissolving in NMP, and stirring until the polyaniline is completely dissolved; weighing 200g of SiO, adding into the polyaniline solution, and stirring to obtain mixed slurry; transferring the mixed slurry to a spray dryer, and introducing N ₂ And carrying out spray drying at 200 ℃ to obtain solid powder.

Comparative example 4

As the anode material in comparative example No. four, si/C material without surface treatment, hereinafter referred to as "Si/C blank" for short.

Comparative example 5

Silica polymeric particles, hereinafter referred to as "SiO-agg blanks" were prepared.

The specific implementation steps are as follows:

adding silica powder with the D50 of 5 mu m into an ethanol solution to obtain silica slurry; the silica slurry was subjected to a sanding treatment using zirconia balls having a diameter of 3 mm. Wherein, the ball-material ratio is 10, the rotating speed is 3000rpm, and the sanding time is 30min. And transferring the silica slurry subjected to sanding treatment into a closed spray drying container, and performing spray drying treatment under the conditions that the speed of a centrifugal atomizing disc is 15000rpm, the atomizing temperature is 150 ℃ and the drying medium is N2 to obtain the silica polymeric particles.

Testing of Material Properties

The composite positive electrode material "ANFs-NCM811-0.05" prepared in example 1 and the positive electrode material "NCM811 blank" prepared in comparative example 1 were respectively matched with a graphite negative electrode to assemble two groups of soft-package batteries with a capacity of 4Ah, and the two groups of batteries were designed identically. Specifically, the negative electrode surface density is 12.8mg/cm2, the compacted density is 1.7g/cm3, the positive electrode surface density is 20.7mg/cm2, the compacted density is 3.5g/cm3, and the N/P ratio is 1.1.

And (3) carrying out a cyclic charge-discharge test on the two groups of batteries at the current density of 1C, testing the capacity retention rate after 1000cyls, disassembling the positive pole piece, and testing the expansion rate of the positive pole piece. The test results are shown in table 1 below:

TABLE 1

As shown in Table 1, the retention rate of the capacity of the positive electrode sheet after 1000 cycles is improved by 6% and the expansion rate of the positive electrode sheet is improved by 2% relative to the 'NCM 811 blank' and 'ANFs-NCM 811-0.05'. From the results, the aramid nano-fiber (ANFs) composite ternary positive electrode material (NCM 811) is adopted as the positive electrode material, so that the expansion of the positive electrode piece can be limited, and the electrical property of the battery can be improved. This is because, when charging to 4.3V, the polycrystalline nickelic material releases nearly 80% of lithium, the crystal grains shrink, the microstress change is severe, when discharging, the polycrystalline nickelic material embeds lithium, the crystal grain volume expands again, the repeated shrinkage and expansion of the crystal grains lead to lattice collapse and crystal grain microcracks, which in turn causes irreversible expansion and thickness increase of the pole piece. Meanwhile, the contact among the particles is lost, the conductivity is reduced, even the conductive network is lost, and the electrical property is reduced.

"ANFs-SiO-0.1", "ANFs-SiO-0.5", "ANFs-SiO-1", "PSA-SiO-agg-0.5", "POD-Si/C-1" prepared in examples 2 to 6, and "PUR-SiO-0.1", "PANI-SiO-0.5", "Si/C blank" and "SiO-agg blank" prepared in comparative examples 1 to 5 were each prepared in accordance with composite electrode materials: conductive agent (SP): binder =75%:15%: preparing slurry and a negative pole piece according to the proportion of 10%, and matching with a metal lithium positive pole to prepare the button cell.

The ten groups of buckle-type batteries prepared above were tested, including reversible gram capacity, first efficiency, rate capability, 50 cycls cycle capacity retention rate and negative electrode sheet swelling condition, and the test results are shown in table 2 below:

TABLE 2

As shown in table 2, the gram capacity, first time efficiency and rate capability of the composite electrode material remained substantially unchanged relative to the electrode material without surface treatment. In other words, the organic fiber coating on the surface of the cathode core material does not affect the basic electrochemical performance of the core material. It is worth noting that compared with the negative electrode material without surface treatment, after the battery is cycled for 50 cycles, the expansion rate of the composite negative electrode pole piece is obviously improved. Therefore, the composite negative electrode material with the organic fiber coating layer on the surface has the obvious effect of reducing the expansion of the pole piece.

It should be understood that the composite electrode material provided in the embodiments of the present application is not limited to the above-mentioned examples, and the core material and the organic fiber may be selected from other materials based on the core concept of coating the surface of the core material with an organic fiber coating layer having a skeleton structure, which is not limited in the present application.

As can be seen from the above embodiments, the present application provides a composite electrode material, including an electrode material core and an organic fiber coating layer having a skeleton structure, where the organic fiber coating layer is compounded on the surface of the electrode material core through bonding; the organic fiber contains at least one of-CO-NH-and-C = N-, and a benzene ring structure. Wherein, the organic fiber contains-CO-NH-or-C = N-which can form abundant hydrogen bonds with-OH on the surface of the electrode material core, so that the organic fiber is combined on the surface of the electrode material core in an intertwined manner, thereby forming a firm coating layer with a skeleton structure on the surface of the electrode material core. The high strength characteristic and the smaller tensile strain of the organic fiber coating layer can limit the volume expansion of the electrode material, and meanwhile, the coating layer is not easy to generate plastic deformation.

In addition, the embodiment of the application also provides a lithium battery, which comprises a positive electrode material, electrolyte, a diaphragm and a negative electrode material, and is characterized in that the positive electrode material or the negative electrode material adopts the composite electrode material.

The embodiment of the application further provides an electronic device, including charge and discharge circuit and power consumption component, still include above-mentioned lithium cell, the lithium cell is connected with charge and discharge circuit, charges or for the power supply of power consumption component through charge and discharge circuit.

The same and similar parts in the various embodiments in this specification may be referred to each other. In particular, for the embodiments, since they are substantially similar to the method embodiments, the description is simple, and the relevant points can be referred to the description in the method embodiments.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention.

Claims

1. The composite electrode material is characterized by comprising an electrode material inner core and an organic fiber coating layer, wherein the organic fiber coating layer is compounded on the surface of the electrode material inner core through bonding;

the organic fiber contains at least one of-CO-NH-and-C = N-, and a benzene ring structure.

2. The composite electrode material according to claim 1, wherein the organic fiber further contains-COOH and/or-NH ₂ 。

3. The composite electrode material according to claim 2, wherein the organic fiber is present in the composite electrode material in an amount of 0.05 to 1% by mass.

4. The composite electrode material according to claim 1, wherein the benzene ring structure is located in a macromolecular chain of the organic fiber.

5. The composite electrode material according to claim 4, wherein the organic fibers have a breaking strength of greater than 3 cN-dtex ^-1 The initial modulus of the organic fiber is more than 50cN dtex ^-1 。

6. The composite electrode material according to claim 4, wherein the organic fiber coating layer has a thickness of 10nm to 200nm.

7. The composite electrode material according to claim 6, wherein the organic fibers have a diameter of 5nm to 60nm and a length of 1 μm to 20 μm.

8. The composite electrode material of claim 1, wherein the organic fiber is an aramid fiber, a polyaroxadiazole fiber, or an polysulfonamide fiber.

9. The composite electrode material of claim 8, wherein the aramid fiber has an aramid chain link content of greater than 85%, a diameter of 5nm to 40nm, and a length of 2 μm to 20 μm.

10. The composite electrode material according to claim 1, wherein the composite electrode material comprises composite particles and/or polymeric particles, the composite particles comprise an electrode material core and an organic fiber coating layer compounded on the surface of the electrode material core by bonding, and the polymeric particles are formed by polymerization of the composite particles.

11. The composite electrode material according to claim 10, wherein the composite particles comprise primary composite particles and secondary composite particles, the inner core of the primary composite particles is the inner core of the electrode material, and the inner core of the secondary composite particles is the polymeric particles formed by polymerizing the primary composite particles.

12. A composite electrode material according to claim 10, further comprising a conductive agent and/or an ionic conductor.

13. The composite electrode material according to claim 12, wherein the conductive agent and/or the ion conductor is coated on the surface of the composite particles and/or the polymeric particles or mixed between the composite particles and/or the polymeric particles.

14. The composite electrode material of claim 10, wherein the conductive agent comprises a combination of one or more of amorphous carbon, soft carbon, hard carbon, graphite, carbon nanotubes, graphene, metal particles.

15. The composite electrode material of claim 1, wherein the electrode material comprises a ternary positive electrode material, a silicon-based, tin-based, sulfur-based, metallic lithium negative electrode material.

16. A method of making a composite electrode material, the method comprising:

preparing an organic fiber solution, wherein the molecular structure of the organic fiber contains at least one of-CO-NH-and-C = N-, and a benzene ring structure;

adding an electrode material into the organic fiber solution according to a preset composite proportion, and stirring until the electrode material is uniformly dispersed;

a composite electrode material according to claim 1, which is obtained by drying a mixed solution of an electrode material and an organic fiber.

17. A composite electrode material produced by the production method according to claim 16.

18. Use of the composite electrode material of claim 1 in the field of the preparation of lithium batteries.

19. A lithium battery comprising a positive electrode material, an electrolyte, a separator and a negative electrode material, wherein the positive electrode material or the negative electrode material is the composite electrode material according to any one of claims 1 to 15.

20. An electronic device comprising a charging and discharging circuit and an electric element, further comprising the lithium battery of claim 19, wherein the lithium battery is connected to the charging and discharging circuit, and is charged by the charging and discharging circuit or supplies power to the electric element.