Multifunctional composite current collector with layered structure, electrode plate and battery

Abstract

The invention provides a multifunctional composite current collector with a layered structure, an electrode plate and a battery, and relates to the technical field of lithium ion batteries. Comprising a polymer substrate layer, a metal conductive layer, a metal oxide layer and a conductive polymer layer, the metal conductive layers are formed on the upper surface and the lower surface of the macromolecule substrate layer, metal oxide layers are arranged on the sides, away from the macromolecule substrate layer, of the two metal conductive layers respectively, and conductive polymer layers are formed on the sides, away from the metal conductive layers, of the two metal oxide layers respectively. Through the scheme, the whole composite current collector has the remarkable advantages of light weight, good flexibility, high interface stability, excellent conductivity and the like.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to a multifunctional layered composite current collector, electrode sheet, and battery. Background Technology

[0002] With the rapid development of portable electronic devices, electric vehicles, and energy storage systems, the performance requirements for lithium-ion batteries are increasing, especially in terms of energy density, safety, cycle life, and manufacturing cost. As a key component in batteries used for collecting and conducting electrons, the current collector has a significant impact on the overall battery performance. Currently, traditional metal foil current collectors (such as copper and aluminum foil) are still widely used in negative and positive electrode systems, but they face significant bottlenecks in terms of flexibility, lightweighting, and interface stability. On the one hand, metal foil materials are inherently heavy, failing to meet the requirements of flexible batteries or wearable devices for thinness and flexibility. On the other hand, the interfacial bonding between the metal foil and the active material is limited, making it prone to desorption and pulverization under long-cycle or high-rate conditions, leading to capacity decay and safety hazards. Furthermore, exposed conductive metals in the electrolyte environment are susceptible to corrosion, hydrogen evolution, or side reactions, reducing battery stability and lifespan. Additionally, the insufficient corrosion resistance of existing current collectors also affects product lifespan. Summary of the Invention

[0003] This invention discloses a multifunctional layered composite current collector, which aims to solve the problems mentioned above.

[0004] The present invention adopts the following solution: A multifunctional layered composite current collector includes: a polymer substrate layer, a metal conductive layer, a metal oxide layer, and a conductive polymer layer; the metal conductive layer is formed on the upper and lower surfaces of the polymer substrate layer, and a metal oxide layer is respectively disposed on the side of the two metal conductive layers away from the polymer substrate layer, and a conductive polymer layer is formed on the side of the two metal oxide layers away from the metal conductive layer.

[0005] Furthermore, the polymeric substrate layer includes one of PET, PP, or PI.

[0006] Furthermore, the thickness of the polymer substrate layer is 3μm~8μm.

[0007] Furthermore, the metal conductive layer includes one of copper, aluminum, nickel, iron, chromium, titanium, molybdenum, and cobalt to provide an efficient current conduction path.

[0008] Furthermore, the thickness of the metal conductive layer is 800nm~1600nm.

[0009] Furthermore, the metal oxide layer is one of titanium oxide, tin oxide, niobium oxide, molybdenum oxide, and manganese oxide, in order to enhance the corrosion resistance of the current collector interface and improve the interface stability.

[0010] Furthermore, the thickness of the metal oxide layer is 10 nm to 100 nm.

[0011] Furthermore, the conductive polymer layer is one of polyaniline, polypyrrole, polythiophene, and poly3,4-ethylenedioxythiophene, and its thickness is 50~200nm, in order to enhance the adhesion performance between the polymer layer and the electrode material and reduce the wetting effect of the lithium-ion battery electrolyte to improve corrosion resistance.

[0012] The present invention also provides an electrode sheet made of a composite current collector with a multifunctional layered structure.

[0013] The present invention also provides a battery in which at least one of the positive and negative electrodes employs the aforementioned electrode sheet.

[0014] Beneficial effects: In this design, the polymer substrate layer possesses excellent mechanical strength and flexibility, supporting the overall structure. A conductive metal layer formed on the polymer substrate layer collects and conducts electrons, improving current efficiency. A metal oxide layer formed on the conductive metal layer exhibits excellent chemical stability and corrosion resistance, effectively isolating the metal layer from the electrolyte and suppressing side reactions. A conductive polymer layer formed on the metal oxide layer enhances the adhesion of the electrode material, improving adhesion and reducing the wetting effect of the lithium-ion battery electrolyte, thereby improving corrosion resistance and ultimately enhancing the battery's cycle stability and rate performance. The overall composite current collector has significant advantages such as light weight, good flexibility, high interface stability, and excellent conductivity, making it suitable for current collector applications in high-energy-density and high-safety lithium-ion batteries. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the multifunctional layered composite current collector according to an embodiment of the present invention; Figure 2 This is a SEM image of the layered composite current collector of Embodiment 2 of the present invention; Figure label: 1. Polymer substrate layer; 2. Conductive metal layer; 3. Metal oxide layer; 4. Conductive polymer layer. Detailed Implementation

[0016] Example 1 Combination Figure 1This embodiment provides a multifunctional layered composite current collector, including a polymer substrate layer 1, a metal conductive layer 2, a metal oxide layer 3, and a conductive polymer layer 4. The metal conductive layers 2 are formed on both sides of the polymer substrate layer 1. The metal oxide layer 3 is disposed on the side of the two metal conductive layers 2 away from the polymer substrate layer 1, and the conductive polymer layer 4 is formed on the side of the two metal oxide layers 3 away from the metal conductive layers 2.

[0017] By setting a metal oxide layer 3 on the conductive metal layer 2, a dense barrier layer is formed on the surface of the conductive metal layer, which effectively prevents corrosive substances such as HF and moisture in the electrolyte from directly contacting the metal, reducing the occurrence of side reactions, and thus delaying the aging of the current collector.

[0018] In this embodiment, a conductive polymer layer 4 is prepared on the metal oxide layer 3. The amino and hydroxyl functional groups in the conductive polymer can form hydrogen bonds, π-π interactions, or chemical bonds with active materials (such as graphite, silicon, lithium manganese oxide, etc.) to form a good interfacial bond, thereby improving the overall mechanical stability of the electrode. At the same time, the conductive polymer can reduce the wetting effect of the electrolyte, thereby further improving the current collector's resistance to electrolyte corrosion and thus increasing the service life of the product.

[0019] In this embodiment, the polymer substrate 1 is one of polyethylene terephthalate (PET), polypropylene (PP), and polyimide (PI), with a thickness ranging from 3 μm to 8 μm. Preferably, the polymer substrate 1 is a polyethylene terephthalate (PET) substrate, with a thickness greater than that of the metal conductive layer 2, the metal oxide layer 3, and the conductive polymer layer 4. This provides good flexibility, heat resistance, and mechanical stability, allowing it to replace traditional copper or aluminum foil, reducing battery weight, increasing energy density, and improving safety. The polymer substrate 1 is designed to be thicker than the metal conductive layer 2, the metal oxide layer 3, and the conductive polymer layer 4 because the polymer substrate (such as PET, PI, or PP) forms the "skeleton" of the entire composite current collector, determining the structure's mechanical strength, flexibility, and dimensional stability. If the substrate is too thin, it cannot withstand the coating stress and the rolling pressure during electrode fabrication, and the stress can easily be transferred to the metal / functional layer, leading to cracking or peeling. By maintaining a substrate layer thickness greater than the total thickness of other functional layers, it is ensured that the current collector will not deform or warp during battery manufacturing processes such as winding, bending, and compaction. Furthermore, the polymer substrate itself has a low density (approximately 1.3). Much lighter than metals, polymer films can be thicker to provide mechanical support without significantly increasing mass. A thicker substrate also provides flexible cushioning, preventing damage to the electrode sheets during bending or cyclic expansion. Metal conductive layers primarily provide an electron transport network; 100–1000 nm is usually sufficient for low resistance, while excessive thickness increases weight and cost. Metal oxide layers mainly provide protection and interface stabilization; 10–200 nm forms a dense protective layer, while excessive thickness hinders electron transport. Conductive polymer layers primarily improve interfacial bonding and buffer stress; tens to hundreds of nanometers are sufficient, while excessive thickness leads to increased resistance. Finally, polymer films need to be at least in the micrometer range to ensure tension and stability during roll-to-roll coating, sputtering, and electroplating processes; too thin a film is prone to wrinkling and tearing.

[0020] In this embodiment, the metal conductive layer 2 is one of copper, aluminum, nickel, iron, chromium, titanium, molybdenum, and cobalt, with a thickness ranging from 800nm ​​to 1600nm, preferably from 1000nm to 1200nm. It is deposited by methods such as magnetron sputtering, electroplating, or vapor deposition, providing an efficient electronic conduction path and ensuring that the entire electrode structure has sufficient conductivity.

[0021] In this embodiment, the metal oxide layer 3 is one of titanium oxide (TiO2), tin oxide (SnO2), niobium oxide (Nb2O5), molybdenum oxide (MoO3), and manganese oxide (MnO2), with a thickness ranging from 10 nm to 100 nm, preferably 50-80 nm. It can be formed by deposition using the sol-gel method. The metal oxide has chemical inertness and electrochemical stability, and can form a dense barrier layer on the metal surface.

[0022] In this embodiment, the conductive polymer layer 4 is one of polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), and poly3,4-ethylenedioxythiophene (PEDOT), with a thickness ranging from 50 nm to 200 nm, preferably from 100 nm to 120 nm. It can be prepared by in-situ oxidative polymerization, electrochemical polymerization, etc. As a functional layer in contact with the battery active material, it can increase the adhesion to the active material, improve the adhesion, reduce the electrolyte wetting effect, and improve corrosion resistance.

[0023] Example 2 like Figure 2 As shown, a composite current collector was prepared by using polyaniline (PANI) as the conductive polymer layer 4 with a thickness of 100 nm; tin dioxide (SnO2) as the metal oxide layer 3 with a thickness of 50 nm; copper (Cu) as the conductive metal layer 2 with a thickness of 1 μm; and polyethylene terephthalate (PET) as the polymer substrate layer 1 with a thickness of 6 μm.

[0024] Example 3 This embodiment provides an electrode sheet, comprising layers of active material stacked sequentially, and the composite current collector described in Embodiment 2. Specifically, graphite is used as the negative electrode active material and coated onto the composite current collector of Embodiment 2.

[0025] Comparative Example 1 This comparative example relates to a composite current collector, comprising a polymer substrate layer 1 and a metal conductive layer 2. The metal conductive layer 2 is formed on both sides of the polymer substrate layer 1. The only difference from Example 2 is that there is no metal oxide layer 3 and conductive polymer layer 4. All other operations are the same, and a composite current collector Cu / PET is prepared.

[0026] Comparative Example 2 This comparative example relates to an electrode sheet, comprising layers of active material stacked sequentially, and the composite current collector described in Comparative Example 1.

[0027] The adhesion of electrode materials to each current collector was evaluated by peel strength test; 1 μL of electrolyte was dropped onto the current collector, and the diffusion diameter of the electrolyte on each current collector within 10 s was observed to assess the wetting effect of the current collector on the electrolyte; XPS analysis was performed on the current collectors after immersion in the electrolyte for 20 days to investigate the product composition on the surface of each current collector, thereby determining the degree of side reaction.

[0028] The experimental results are shown in Table 1: Table 1

[0029] As shown in Table 1, the composite current collector prepared in Example 2, compared to directly using Cu / PET as the composite current collector, can effectively reduce the wetting effect of the lithium-ion battery electrolyte, thereby improving the electrolyte corrosion resistance of the composite current collector. XPS analysis of the composite current collectors in Example 2 and Comparative Example 1 revealed that both composite current collectors contain the byproduct Li. x PO y The formation of LiF and Cu(OH)2 was observed, but the composite current collector in Example 2 did not produce CuF2 byproducts compared to Comparative Example 1, indicating that the functional layer structure can effectively suppress the occurrence of side reactions. Meanwhile, using graphite as the negative electrode active material, coated onto the composite current collector, and conducting peel strength tests on the active material layer and composite current collector of Example 3 and Comparative Example 2, it was found that the peel strength between the electrode material layer and the composite current collector in Example 3 was 0.332 compared to Comparative Example 2. It has been increased to 0.386 This indicates that the conductive polymer layer in contact with the active material can effectively enhance the adhesion between the composite current collector and the active material, thereby improving the adhesion of the active material and thus improving the cycle performance and rate performance of the battery.

[0030] Example 4 This embodiment also provides a lithium battery, including a cathode electrode sheet, an anode electrode sheet, a separator, and an electrolyte, wherein the electrode sheet is configured as described in Embodiment 3 as needed. It should be understood that the above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0031] The accompanying drawings used in the above description of the embodiments only illustrate certain embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A multifunctional layered structured composite current collector, characterized by, It comprises a polymer base layer, a metal conductive layer, a metal oxide layer and a conductive polymer layer; the metal conductive layer is formed on the upper and lower surfaces of the polymer base layer, and the side of the two metal conductive layers away from the polymer base layer is respectively provided with a metal oxide layer, and the side of the two metal oxide layers away from the metal conductive layer is formed with a conductive polymer layer. The polymer base layer comprises one of PET, PP or PI.

2. The multifunctional layered structured composite current collector of claim 1, wherein, The thickness of the polymer base layer is 3-8 μm.

3. The multifunctional layered structured composite current collector of claim 2, wherein, The metal conductive layer comprises one of copper, aluminum, nickel, iron, chromium, titanium, molybdenum or cobalt, for providing an efficient conduction path for current.

4. The multifunctional layered structured composite current collector of claim 1, wherein, The thickness of the metal conductive layer is 800-1600 nm.

5. The multifunctional layered structured composite current collector of claim 4, wherein, The metal oxide layer is one of titanium oxide, tin oxide, niobium oxide, molybdenum oxide or manganese oxide, for enhancing the corrosion resistance of the current collector interface and improving the interface stability.

6. The multifunctional layered structured composite current collector of claim 1, wherein, The thickness of the metal oxide layer is 10-100 nm.

7. The multifunctional layered structured composite current collector of claim 6, wherein, The conductive polymer layer is one of polyaniline, polypyrrole, polythiophene or poly(3,4-ethylenedioxythiophene), and its thickness is 50-200 nm, for enhancing the adhesion between the electrode material and reducing the infiltration effect of the lithium ion battery electrolyte to improve the corrosion resistance.

8. The multifunctional layered structured composite current collector of claim 1, wherein, The multifunctional layered composite current collector is made by any one of claims 1-5.

9. An electrode sheet characterized by The positive electrode and the negative electrode of the lithium ion battery at least one of which adopts the electrode sheet of claim 9.

10. A battery, characterized by ​

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