Composite lithium battery pole piece

Abstract

The utility model discloses a composite lithium battery pole piece which comprises a current collector layer, active substance layers are respectively arranged on two sides of the current collector layer, each active substance layer is composed of a plurality of active substance sub-layers made of different materials, the active substance sub-layer close to the current collector layer is a basic active substance layer, and the active substance sub-layer close to the current collector layer is a non-basic active substance layer. The active material sub-layers are arranged on the current collector layer, the active material sub-layers far away from the current collector layer are high-performance active material layers, transition layers are arranged between the adjacent active material sub-layers, and the transition layers are composed of conductive materials and binders. The energy density and the charge-discharge performance of the pole piece are improved, the bonding force and the conductivity between the adjacent active material sub-layers are enhanced by arranging the transition layers, the internal resistance is reduced, the rate capability of the battery is improved, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery devices, in particular to a composite lithium battery pole piece. Background Art

[0002] With the rapid development of electronic devices and new energy fields, the requirements for lithium battery performance are constantly increasing. Current lithium battery pole pieces still face many challenges in terms of energy density, cycle life, charge and discharge performance, etc. The traditional single active material layer structure limits the further improvement of battery performance, and the bonding and conductivity between different active materials need to be optimized. There is a lack of effective protection measures to deal with electrolyte erosion and active material shedding. Summary of the invention

[0003] 1. Technical issues

[0004] The utility model aims to provide a composite lithium battery pole piece, which solves the performance limitations of existing lithium battery pole pieces through innovative structural design and material selection, improves the comprehensive performance of the battery, and meets the growing market demand.

[0005] (II) Technical content

[0006] In order to solve the above technical problems, the technical solution of the utility model is: a composite lithium battery pole piece, including a current collector layer, active material layers are respectively provided on both sides of the current collector layer, the active material layer is composed of multiple layers of active material sub-layers of different materials, the active material sub-layer close to the current collector layer is a basic active material layer, the active material sub-layer away from the current collector layer is a high-performance active material layer, a transition layer is arranged between adjacent active material sub-layers, and the transition layer is composed of a conductive material and a binder.

[0007] Furthermore, the basic active material layer is made of lithium iron phosphate material.

[0008] Furthermore, the high-performance active material layer is made of lithium nickel cobalt manganese oxide or lithium cobalt oxide material.

[0009] Furthermore, the conductive material includes one or more of conductive carbon black, carbon nanotubes, graphene, and metal nanoparticles.

[0010] Furthermore, the surface of the active material layer is covered with a protective layer.

[0011] Furthermore, the material of the protective layer is one of polyvinylidene fluoride, aluminum oxide, silicon nitride, and polyimide.

[0012] Furthermore, the current collector layer is aluminum foil or copper foil.

[0013] (III) Technical Effect

[0014] Compared with the prior art, the utility model has the following advantages:

[0015] 1. The use of multiple layers of active material sub-layer structure with different materials fully utilizes the advantages of different active materials and improves the energy density and charge and discharge performance of the electrode.

[0016] 2. The setting of the transition layer enhances the bonding force and conductivity between adjacent active material sublayers, reduces the internal resistance, and improves the rate performance and cycle life of the battery.

[0017] 3. The protective layer can effectively prevent the active material from falling off and the electrolyte from eroding, thus enhancing the stability and service life of the electrode.

[0018] 4. The basic active material layer uses materials with high stability, and the high-performance active material layer uses materials with high specific capacity and good rate performance, achieving performance balance and optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The utility model is a structural schematic diagram of a composite lithium battery pole piece.

[0020] As shown in the figure: 1. Current collector layer; 2. Basic active material layer; 3. High-performance active material layer; 4. Transition layer; 5. Protective layer. DETAILED DESCRIPTION

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", "center", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction structure and operation. Therefore, they should not be understood as limitations on the present invention.

[0022] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "provided with", "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, it can be a mechanical connection, it can be an electrical connection, it can be a direct connection, it can be indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0024] Combined with Figure 1A composite lithium battery pole piece includes a current collector layer 1, the current collector layer 1 is aluminum foil or copper foil, active material layers are respectively arranged on both sides of the current collector layer 1, and the active material layers are composed of multiple active material sublayers of different materials. The active material sublayer close to the current collector layer is a basic active material layer 2, and the active material sublayer away from the current collector layer is a high-performance active material layer 3. A transition layer 4 is arranged between adjacent active material sublayers, and the transition layer 4 is composed of a conductive material and a binder.

[0025] The basic active material layer 2 is made of lithium iron phosphate material, and the high-performance active material layer 3 is made of lithium nickel cobalt manganese oxide or lithium cobalt oxide material.

[0026] The conductive material includes one or more of conductive carbon black, carbon nanotubes, graphene, and metal nanoparticles.

[0027] The surface of the active material layer is covered with a protective layer 5 , and the material of the protective layer 5 is one of polyvinylidene fluoride, aluminum oxide, silicon nitride, and polyimide.

[0028] The functions of each layered structure of the utility model are as follows:

[0029] 1. Current collector layer (aluminum foil or copper foil): It mainly conducts electrons, evenly transferring the current outside the battery to the active material layer, and at the same time, it conducts the electrons generated by the active material layer to the external circuit during discharge.

[0030] 2. Basic active material layer (such as lithium iron phosphate): provides stable capacity and long cycle life, ensuring the basic performance of the battery during multiple charge and discharge processes.

[0031] 3. High-performance active material layer (such as lithium nickel cobalt manganese oxide or lithium cobalt oxide): provides higher specific capacity and fast charge and discharge capabilities when high power is required, improving the overall performance of the battery.

[0032] 4. Transition layer (conductive material and binder): enhances the electronic conduction between adjacent active material sublayers, improves interface contact, reduces resistance, and improves the rate performance of the battery.

[0033] 5. Protective layer (such as polyvinylidene fluoride): prevents chemical erosion of active substances by electrolyte, reduces the shedding of active substances, enhances the mechanical strength and stability of the electrode, and extends the service life of the battery.

[0034] Its working principle is as follows: when the lithium battery is charged and discharged, the current is evenly distributed to the active material layer through the current collector layer. During the charging process, lithium ions are embedded from the electrolyte into the active material layer; during discharge, lithium ions are de-embedded from the active material layer back into the electrolyte. Multiple layers of active material sublayers of different materials work together. The basic active material layer provides stable capacity and cycle performance, while the high-performance active material layer plays a role at high power output, achieving good performance of the battery under different operating conditions. The conductive material in the transition layer promotes the rapid transmission of electrons between different active material sublayers, reduces internal resistance, and improves the charge and discharge efficiency of the battery. The protective layer effectively blocks the erosion of the electrolyte on the active material and prevents the active material from falling off, thereby ensuring the long-term stability and cycle life of the battery.

[0035] The production process is as follows:

[0036] 1. Prepare the current collector layer: Select aluminum foil or copper foil as the current collector layer, clean it and perform surface treatment to improve the bonding strength with the active material layer.

[0037] 2. Prepare the basic active material layer: Mix the lithium iron phosphate material with the conductive agent and the binder in a certain proportion, add a solvent to make a slurry, and evenly apply it on one side of the current collector layer by coating or spraying.

[0038] 3. Prepare the transition layer: Mix the conductive material (such as conductive carbon black) and the binder to make a transition layer slurry, and apply it on the basic active material layer.

[0039] 4. Prepare a high-performance active material layer: Mix lithium nickel cobalt manganese oxide or lithium cobalt oxide material with a conductive agent and a binder in proportion to form a slurry, and apply it on the transition layer.

[0040] 5. Coating a protective layer: Dissolve the selected protective layer material (such as polyvinylidene fluoride) in an appropriate solvent to form a solution, and coat it on the surface of the active material layer.

[0041] 6. Drying and compaction: The coated electrode is dried to remove the solvent and then compacted to improve the density and performance of the electrode.

[0042] The above description of the utility model and its implementation methods is not restrictive. The drawings show only one implementation method of the utility model, and the actual structure is not limited thereto. In short, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the invention of the utility model, they should all fall within the protection scope of the utility model.

Claims

1. A composite lithium battery pole piece, comprising a current collector layer (1), characterized in that: Active material layers are provided on both sides of the current collector layer (1), the active material layers are composed of multiple active material sub-layers of different materials, the active material sub-layer close to the current collector layer is a basic active material layer (2), the active material sub-layer away from the current collector layer is a high-performance active material layer (3), and a transition layer (4) is provided between adjacent active material sub-layers, the transition layer (4) is composed of a conductive material and a binder.

2. A composite lithium battery pole piece according to claim 1, characterized in that: The basic active material layer (2) is made of lithium iron phosphate material.

3. A composite lithium battery pole piece according to claim 1, characterized in that: The high-performance active material layer (3) is made of lithium nickel-cobalt-manganese oxide or lithium cobalt oxide material.

4. A composite lithium battery pole piece according to claim 1, characterized in that: The conductive material includes one or more of conductive carbon black, carbon nanotubes, graphene, and metal nanoparticles.

5. The composite lithium battery pole piece according to claim 1, characterized in that: The surface of the active material layer is covered with a protective layer (5).

6. A composite lithium battery pole piece according to claim 5, characterized in that: The material of the protective layer (5) is one of polyvinylidene fluoride, aluminum oxide, silicon nitride, and polyimide.

7. The composite lithium battery pole piece according to claim 1, characterized in that: The current collector layer (1) is aluminum foil or copper foil.

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