Cuo@pani composite coating modified copper current collector and preparation method thereof

Abstract

This invention discloses a CuO@PANI composite coating modified copper current collector and its preparation method, belonging to the field of negative electrode-free lithium metal battery technology. The invention prepares sheet-like copper oxide via a hydrothermal method, then performs in-situ polymerization in an ice-water bath to obtain a CuO@PANI composite material in-situ coated with polyaniline. This composite material is then mixed with a conductive agent and a binder to form a slurry, which is then coated onto the surface of copper foil to obtain the composite coating modified copper current collector. The modified current collector of this invention possesses both a high density of lithiophilic nucleation sites and high electronic conductivity, which can significantly reduce lithium nucleation overpotential, promote uniform lithium ion deposition, inhibit lithium dendrite growth, and reduce the formation of "dead lithium," effectively improving battery cycle stability, coulombic efficiency, and safety.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, specifically relating to a CuO@PANI composite coating modified copper current collector and its preparation method. Background Technology

[0002] Against the backdrop of a global energy structure accelerating its transition towards cleaner and lower-carbon energy, the rapid development of electric vehicles, smart grids, and portable electronic devices has placed unprecedentedly high demands on the energy density, safety, and cycle life of rechargeable batteries. Currently, the energy density of commercially available lithium-ion batteries is approaching the theoretical limits of their material systems, making it difficult to meet the needs of future technological development. Therefore, developing new battery systems with higher energy density while maintaining safety and cycle stability has become a core issue of common concern for both academia and industry. In this context, electrodeless lithium metal batteries, due to their extremely high theoretical energy density, are considered an important development direction for next-generation energy storage devices.

[0003] However, the fundamental challenge to the commercialization of electrodeless lithium metal batteries lies in the fact that during the first charge, lithium ions are deposited from the positive electrode and deposited on the surface of the negative electrode current collector to form a metallic lithium negative electrode. The smooth and chemically inert surface of commercial copper foil leads to a high lithium deposition overpotential, sparse and unevenly distributed nucleation sites, which easily induces uncontrolled growth of lithium dendrites. Dendrites not only puncture the separator, causing short circuits and other safety hazards, but their repeated breakage also forms "dead lithium," resulting in irreversible loss of active lithium and rapid capacity decay.

[0004] To address the aforementioned issues, research on the modification of current collectors in electrodeless lithium metal batteries has developed into a multi-strategy synergistic approach, focusing on three main directions: three-dimensional structure design, lithiophilic modification, and interface protective layers. Patent publication CN120261459A discloses a method for preparing single-crystal Cu copper foil current collectors through high-temperature annealing. This method utilizes the low lithium migration barrier to achieve uniform lithium deposition, effectively suppressing dendrites and extending the cycle life of electrodeless lithium metal batteries. However, the preparation of single-crystal copper foil requires a sapphire substrate and high-temperature annealing at thousands of degrees Celsius, resulting in high preparation costs. Patent publication CN121123290A discloses a method for constructing a 35 nm ultrathin pre-lithiation MMT-PSS composite modification layer. This coating significantly accelerates lithium-ion desolvation and improves SEI ion conductivity, achieving long-life and high-efficiency cycling in electrodeless lithium metal batteries. However, this modification layer relies on precise pre-lithiation and electrospray processes, making large-scale production difficult.

[0005] Zhang et al. used a simple wet chemical method to grow vertically aligned lithiophilic CuO nanosheets (VA-CuO) in situ on the surface of copper foil. They utilized the three-dimensional array structure to reduce local current density and homogenize lithium-ion distribution, and leveraged the affinity of CuO for lithium to reduce nucleation overpotential, achieving a 94% coulombic efficiency for 180 cycles and stable cycling of a symmetric battery for 700 hours (Advanced Energy Materials, 2018, 8(21): 1703404.). Xiong et al. constructed a lithiophilic polyaniline (PANI) modification layer on the surface of a copper current collector using an in-situ electrochemical polymerization strategy. They utilized the affinity of nitrogen atoms and conjugated π electrons in PANI for lithium to reduce nucleation overpotential and promote uniform lithium deposition, achieving a 99.1% coulombic efficiency for 400 cycles and long-term cycling stability for 1300 hours (Nano Research, 2023, 16(6): 8448-8456.). However, CuO materials alone have insufficient conductivity, and PANI materials alone have limited nucleation sites. Neither of them can simultaneously achieve high lithiophilicity, high conductivity, structural stability, and large-scale preparation.

[0006] In summary, existing current collector modification technologies generally suffer from drawbacks such as limited functionality, poor structural stability, high manufacturing costs, or difficulty in scaling up production. These limitations fail to simultaneously meet the comprehensive requirements of electrodeless lithium metal batteries for lithophilicity, conductivity, mechanical buffering, and large-scale production. Therefore, there is an urgent need to develop a composite-coated modified copper current collector that combines excellent lithophilicity, high electronic conductivity, and good structural stability, while also being able to be manufactured at low cost, high efficiency, and on a large scale. This would fundamentally solve core challenges such as lithium dendrite formation, dead lithium, and interfacial instability. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention aims to provide a CuO@PANI composite coating modified copper current collector that has strong bonding, combines lithium affinity with high conductivity, and can be prepared on a low-cost, large-scale basis via wet chemical methods.

[0008] To achieve its objectives, the present invention employs the following technical solution: This invention provides a CuO@PANI composite coating modified copper current collector, suitable for negative electrode-less lithium metal batteries. Its features are: a sheet-like copper oxide / polyaniline (CuO@PANI) composite coating is loaded on the surface of the copper foil current collector, and the polyaniline is uniformly coated on the surface of the sheet-like copper oxide in situ, forming a multifunctional interface with excellent lithium affinity, high electronic conductivity and good mechanical stability.

[0009] The preparation method of CuO@PANI composite coating modified copper current collector according to the present invention includes the following steps: Step 1: Preparation of flake CuO Under stirring conditions, copper salt solution was added dropwise to sodium hydroxide solution, and stirring was continued until the mixture was homogeneous. The mixed solution was then transferred to a reaction vessel for hydrothermal reaction. After the reaction was completed, the solution was filtered, washed, and vacuum dried to obtain flake CuO.

[0010] The copper salt is selected from one or more of copper nitrate, copper sulfate, copper acetate, copper chloride, and copper oxalate; the hydrothermal reaction temperature is 80~160℃, and the reaction time is 6~24 h.

[0011] Step 2: Preparation of CuO@PANI composite material Aniline was added to deionized water and ultrasonically dispersed evenly. Then, the flake-shaped CuO prepared in step 1 was added, and ultrasonication was continued until fully mixed. Then, under ice-water bath conditions, protic acid and ammonium persulfate solution were added in sequence to initiate in-situ polymerization of aniline. After the reaction was completed, the mixture was filtered, washed, and vacuum dried to obtain CuO@PANI composite material.

[0012] The protic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and benzenesulfonic acid; the ratio of aniline to flake CuO is 50-300 μL: 50-200 mg. The in-situ polymerization time is 10-60 min.

[0013] Step 3: Preparation of modified copper current collector The CuO@PANI composite material obtained in step 2, high conductivity carbon black (SP), sodium carboxyethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 8:1:0.5:0.5, and deionized water was added to grind them into a slurry. The slurry was coated onto the surface of copper foil that had been cleaned and dried with ethanol by a doctor blade coating method. After vacuum drying, CuO@PANI composite coating modified copper current collector was obtained.

[0014] The present invention further provides a negative electrode-free lithium metal battery, which uses the CuO@PANI composite coating modified copper current collector of the present invention as the negative electrode.

[0015] Compared with the prior art, the beneficial effects of the present invention are reflected in: 1. This invention constructs a sheet-like copper oxide / polyaniline (CuO@PANI) composite interface on the surface of copper foil. The sheet-like copper oxide provides high-density lithiophilic nucleation sites, significantly reducing lithium nucleation overpotential and homogenizing lithium ion distribution. The in-situ coating of polyaniline forms a highly conductive and tough interface protective layer, improving the coating structure stability and electronic conductivity. The synergistic effect of these two components allows for precise control of lithium deposition behavior, suppression of lithium dendrite growth, and reduction of "dead lithium" formation, fundamentally improving the cycle life, coulombic efficiency, and safety of electrodeless lithium metal batteries.

[0016] 2. The composite coating of the present invention has strong adhesion to the copper substrate, is not easy to fall off or pulverize, and can maintain the integrity of the interface structure during long-term charging and discharging, thus overcoming the problem of easy failure of traditional ultra-thin decorative layers.

[0017] 3. This invention uses hydrothermal method and ice-water bath in-situ polymerization, which has mild reaction conditions, readily available raw materials, simple operation, and does not require expensive equipment and complex processes. It can achieve industrial scale-up at low cost and high efficiency.

[0018] 4. The composite coating current collector of the present invention can be widely applied to negative electrode-free lithium metal battery systems, has good compatibility, and has important practical value for improving the overall performance of high-energy-density lithium batteries. Attached Figure Description

[0019] Figure 1 Scanning electron microscope image of the sheet-like CuO prepared in Example 1; Figure 2 Scanning electron microscope image of the CuO@PANI composite material prepared in Example 1; Figure 3 X-ray diffraction patterns of the sheet-like CuO and CuO@PANI composite materials prepared in Example 1; Figure 4 Fourier transform infrared spectroscopy (FTIR) image of the CuO@PANI composite material prepared in Example 1; Figure 5 This is a scanning electron microscope image of the CuO@PANI composite material prepared with low aniline addition in Example 2; Figure 6 This is a scanning electron microscope image of the CuO@PANI composite material prepared with high aniline addition in Example 3; Figure 7 A comparison graph showing the coulombic efficiency of half-cells assembled with different current collectors in each embodiment and comparative example; Figure 8 A comparison diagram of lithium nucleation overpotentials for different current collectors in each embodiment and comparative example; Figure 9 This is a comparison graph showing the cycle performance of the full cells assembled with current collectors in Example 1 and Comparative Example 1. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. The embodiments are only used to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0021] Example 1 In this embodiment, the CuO@PANI composite coating modified copper current collector is prepared according to the following steps: Step 1: Preparation of flake CuO Under stirring conditions, 4.0 mL of 0.15 M CuCl2 aqueous solution was added dropwise to 12.0 mL of 4.5 M NaOH solution, and the mixture was stirred continuously for 30 minutes. The mixture was then transferred to a reaction vessel and hydrothermally reacted at 120 °C for 12 h. After the reaction was completed, the mixture was filtered, and the product was washed three times with deionized water and then vacuum dried to obtain flake CuO.

[0022] Step 2: Preparation of CuO@PANI composite material 142.0 μL of aniline was added to 40 mL of deionized water and ultrasonically dispersed evenly. Then, 142 mg of the flake CuO prepared in step 1 was added and ultrasonically dispersed until fully mixed. Under ice-water bath conditions, 3.0 mL of 0.5 M HCl solution and 10 mL of 40.0 mM ammonium persulfate solution were added sequentially to initiate the in-situ polymerization reaction of aniline, and the reaction lasted for 20 min. After the reaction was completed, the product was filtered, washed three times with deionized water, and then vacuum dried to obtain CuO@PANI composite material.

[0023] Step 3: Preparation of modified copper current collector The CuO@PANI composite material obtained in step 2, high conductivity carbon black (SP), sodium carboxyethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 8:1:0.5:0.5, and an appropriate amount of deionized water was added to grind them into a uniform slurry. The slurry was coated onto the surface of copper foil that had been cleaned and dried with ethanol, and then vacuum dried at 60°C for 12 h to obtain CuO@PANI composite coating modified copper current collector. It was then cut into 14 mm round pieces using a cutting machine and denoted as CuO@PANI Cu.

[0024] The sheet-like copper oxide CuO and CuO@PANI composite material in this embodiment were characterized using scanning electron microscopy, and the results are as follows: Figure 1 and 2 As shown, the prepared CuO exhibits a sheet-like structure, with polyaniline adhering to the CuO nanosheets in the CuO@PANI composite material. Through... Figure 3 The XRD pattern further illustrates the successful preparation of CuO. Figure 4 Fourier transform infrared (FTIR) image of CuO@PANI composite material, 1580 cm⁻¹ -1 1490 cm -1 1300 cm -1 The characteristic absorption peaks at the three locations prove the presence of polyaniline.

[0025] Example 2 This embodiment uses the same method as Example 1 to prepare CuO@PANI composite-coated modified copper current collectors, the only difference being that the amount of aniline added is 71 μL. The scanning electron microscope (SEM) image of the obtained sample is shown below. Figure 5 As shown, due to the reduction of aniline, the polyaniline composite onto copper oxide is not uniform, and there are a large number of sheet-like copper oxides without polyaniline attachment.

[0026] Example 3 This embodiment uses the same method as Example 1 to prepare CuO@PANI composite-coated modified copper current collectors, the only difference being that the amount of aniline added is 284 μL. The scanning electron microscope (SEM) image of the obtained sample is shown below. Figure 6 As shown, due to the increase in the amount of aniline added, there is still some remaining after the polyaniline is composited with copper oxide, and it then exists in the form of polyaniline alone.

[0027] Comparative Example 1 Commercial copper foil was cleaned with ethanol to obtain blank copper foil. After vacuum drying, it was cut into 14 mm round pieces using a cutting machine, denoted as Bare Cu.

[0028] Comparative Example 2 Flake-shaped CuO was prepared using the same method as in Example 1. The prepared flake-shaped CuO was mixed with highly conductive carbon black (SP), sodium carboxyethyl cellulose (CMC), and styrene-butadiene rubber (SBR) at a mass ratio of 8:1:0.5:0.5. An appropriate amount of deionized water was added, and the mixture was ground into a uniform slurry. Then, 14 mm discs were formed using the same method as in Example 1, denoted as CuO. Comparative Example 3 142.0 μL of aniline was added to 40 mL of deionized water and ultrasonically dispersed until homogeneous. Under ice-water bath conditions, 3.0 mL of 0.5 M HCl solution and 10 mL of 40.0 mM ammonium persulfate solution were added sequentially to initiate the in-situ polymerization reaction of aniline, which lasted for 20 min. After the reaction, the mixture was filtered, and the product was washed three times with deionized water and then vacuum dried to obtain polyaniline. The prepared polyaniline was mixed with highly conductive carbon black (SP), sodium carboxyethyl cellulose (CMC), and styrene-butadiene rubber (SBR) at a mass ratio of 8:1:0.5:0.5, and an appropriate amount of deionized water was added to grind it into a homogeneous slurry. Then, 14 mm discs were made using the same method as in Example 1, denoted as PANI Cu.

[0029] Using four copper foils from Examples 1, 1, 2, and 3 as electrodes, a lithium sheet as the counter electrode, and Celgard 2400 as the separator, half-cells were assembled under test conditions of 1 mA / cm². 2 1 mAh / cm 2The electrolyte used was prepared by dissolving 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in a mixed solvent of ethylene glycol dimethyl ether (DME) and 1,3-dioxolane (DOL) in a volume ratio of 1:1, and adding 2 wt% lithium nitrate (LiNO3). Figure 7 The graph shows a comparison of coulombic efficiency. It can be seen that the CuO@PANI Cu obtained in Example 1 was stable for nearly 200 cycles with an average coulombic efficiency of over 98%, while the PANI Cu in Comparative Example 3 was stable for only about 90 cycles, the CuO Cu in Comparative Example 2 was stable for only about 120 cycles, and the Bare Cu in Comparative Example 1 was stable for only about 60 cycles. Figure 8 The diagram shows a comparison of lithium nucleation overpotentials. The lithium nucleation overpotential of CuO@PANI Cu is 15.5 mV, that of PANI Cu is 42.1 mV, that of CuO Cu is 21.4 mV, and that of Bare Cu is 49 mV. It is evident that copper oxide composite polyaniline can effectively reduce the lithium nucleation overpotential, which is beneficial for uniform lithium deposition.

[0030] Using lithium iron phosphate as the positive electrode, full-cell tests were conducted on the electrodes in Example 1 and Comparative Example 1. Before the test, a 3mAh / cm³ solution was used. 2 Lithium is pre-deposited to reduce irreversible lithium consumption. Full-cell cycling tests were conducted at 1 C, and the results are as follows: Figure 9 As shown, the initial discharge specific capacity of the full cell assembled with CuO@PANI Cu in Example 1 was 156.9 mAh g. -1 After 300 cycles, the capacity retention was 91.5%. In comparison, the initial discharge specific capacity of a bare copper full cell was 154.6 mAh g⁻¹. -1 After 300 cycles, the capacity retention rate was only 76.6%.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A CuO@PANI composite coating modified copper current collector, characterized in that: A flake-shaped copper oxide / polyaniline CuO@PANI composite coating is loaded on the surface of the copper foil current collector, with polyaniline uniformly coated on the flake-shaped copper oxide surface in situ.

2. A method for preparing the CuO@PANI composite coating modified copper current collector according to claim 1, characterized in that, Includes the following steps: Step 1: Preparation of flake CuO Under stirring conditions, copper salt solution was added dropwise to sodium hydroxide solution, and stirring was continued until the mixture was homogeneous. The mixed solution was then transferred to a reaction vessel for hydrothermal reaction. After the reaction was completed, the solution was filtered, washed, and vacuum dried to obtain flake-like CuO. Step 2: Preparation of CuO@PANI composite material Aniline was added to deionized water and ultrasonically dispersed evenly. Then, the flake-like CuO prepared in step 1 was added, and ultrasonication was continued until fully mixed. Then, under ice-water bath conditions, protic acid and ammonium persulfate solution were added sequentially to initiate in-situ polymerization of aniline. After the reaction was completed, the mixture was filtered, washed, and vacuum dried to obtain CuO@PANI composite material. Step 3: Preparation of modified copper current collector The CuO@PANI composite material obtained in step 2, high conductivity carbon black, sodium carboxyethyl cellulose, and styrene-butadiene rubber were mixed and ground into a slurry with deionized water. The slurry was then coated onto the surface of a copper foil that had been cleaned and dried with ethanol. After vacuum drying, the CuO@PANI composite coating modified copper current collector was obtained.

3. The method of claim 2, wherein: In step 1, the copper salt is selected from one or more of copper nitrate, copper sulfate, copper acetate, copper chloride, and copper oxalate.

4. The method of claim 2, wherein: In step 1, the temperature of the hydrothermal reaction is 80~160℃, and the reaction time is 6~24 h.

5. The method of claim 2, wherein: In step 2, the protic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and benzenesulfonic acid.

6. The method of claim 2, wherein: In step 2, the ratio of aniline to flake CuO is 50~300 μL: 50~200 mg.

7. The method of claim 2, wherein: In step 2, the in-situ polymerization time is 10~60 min.

8. The method of claim 2, wherein: In step 3, the mass ratio of CuO@PANI composite material, highly conductive carbon black, sodium carboxyethyl cellulose, and styrene-butadiene rubber is 8:1:0.5:0.

5.

9. A negative electrode-free lithium metal battery, characterized by: The CuO@PANI composite coating modified copper current collector described in claim 1 is used as the negative electrode.

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