A lithium ion battery negative electrode current collector and a preparation method and application thereof
By forming a β-cyclodextrin and Nafion composite interface film on the surface of the negative electrode current collector of a lithium-ion battery, the problem of lithium dendrite growth was solved, achieving uniform lithium-ion deposition and high cycle life and safety of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGDU TECH UNIV
- Filing Date
- 2026-05-19
- Publication Date
- 2026-06-16
Smart Images
Figure CN122224752A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery negative electrode current collector, its preparation method, and its application. Background Technology
[0002] In lithium-ion batteries, the deposition behavior of lithium ions on the surface of copper current collectors directly affects battery performance and safety. However, the uncontrolled growth of lithium dendrites on the negative electrode during charging and discharging can easily puncture the separator and cause short circuits, severely restricting its commercial application.
[0003] Existing liquid lithium metal batteries use organic "dual-ion conductor" electrolytes. During charging and discharging, lithium ions and anions migrate in opposite directions. Anions, not participating in the electrode reaction, accumulate on the negative electrode side, forming a space charge layer and inducing concentration polarization. This exacerbates the non-uniform distribution of the interfacial electric field, inducing lithium dendrite nucleation and growth. To suppress dendrite formation, current technologies mainly employ interface modification: such as coating the current collector or separator surface with inorganic nanoparticles like Al₂O₃ to physically block dendrites, or coating with polymer layers like PVDF or PEO to improve wettability. However, inorganic coatings are brittle and prone to cracking and flaking; dense polymer coatings reduce ionic conductivity and increase internal resistance. More importantly, both only provide passive blocking and cannot selectively regulate ion migration or prevent anion accumulation, thus failing to eliminate the root cause of dendrite formation.
[0004] Therefore, there is an urgent need to develop a negative electrode current collector modification material with ion-selective transport function in order to fundamentally suppress the growth of lithium dendrites. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing and applying a lithium-ion battery negative electrode current collector that can selectively transport ions.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a negative electrode current collector for a lithium-ion battery, comprising the following steps: S1. Coat the surface of copper foil with a composite solution of β-cyclodextrin and Nafion; S2. Vacuum pre-dry the coated copper foil; S3. The pre-dried copper foil is annealed at high temperature. The high-temperature annealing in step S3 is vacuum drying at 80~120℃; The method for preparing the β-cyclodextrin and Nafion complex solution includes preparing an aqueous solution of β-cyclodextrin and Nafion and then ultrasonically vibrating it; wherein the mass ratio of β-cyclodextrin to Nafion is 2:1 to 6:1; and the ultrasonic vibration time is 10 to 60 min.
[0007] In preparing the negative electrode current collector for lithium-ion batteries, this invention introduces β-cyclodextrin. Utilizing the unique external hydrophilic and internal hydrophobic cavity structure (inner diameter approximately 0.6-0.78 nm) of β-cyclodextrin, it acts as a "lithium-ion molecular sieve," providing a low-barrier transport channel for lithium ions, reducing desolvation energy, and blocking large-sized solvated anions. This allows it to maintain high ionic conductivity while blocking dendrites on the current collector surface, without significantly increasing the battery's internal resistance. Simultaneously, perfluorosulfonic acid resin (Nafion) is introduced in combination with β-cyclodextrin to form an interfacial film on the current collector surface. Besides acting as a polymer backbone to allow β-cyclodextrin to adhere to the current collector surface, this component contains negatively charged sulfonic acid groups (-SO3⁻) that generate a Donnan repulsion effect, further electrostatically repelling anions. This fundamentally eliminates concentration polarization, preventing the lithium deposition process from being interfered with by anion accumulation. Meanwhile, both β-cyclodextrin and Nafion have excellent chemical resistance and a wide electrochemical window (stable from 0 to 4.5V). Compared with ordinary biodegradable biological proteins (such as silk protein), this composite membrane is more stable under long-term cycling and high voltage, and is less prone to decomposition or side reactions.
[0008] Within the preferred ratio range of β-cyclodextrin and Nafion, the lithium-ion battery negative electrode current collector prepared by the method of the present invention possesses high ion transport number and sufficiently strong mechanical toughness, enabling it to firmly adhere to the current collector surface, forming a "single ion channel," reducing concentration polarization, and thus reducing the formation of dendritic lithium. When the proportion of β-cyclodextrin in the solution is too low, the prepared current collector surface will lack sufficient molecular sieve channels, resulting in a weakened "pore size sieving" effect, a significant decrease in ion transport number, and an inability to effectively block large-sized anions. When the proportion of Nafion in the solution is too low, it will lead to poor film formation, and the resulting current collector interface film will lack sufficient mechanical toughness, resulting in surface cracks or powdering, failure of physical barrier ability, and easy direct penetration of electrolyte into the copper foil surface.
[0009] High-temperature annealing promotes microphase separation of Nafions, forming ordered hydrophilic ion cluster channels, which is a crucial step in improving the lithium-ion conductivity at the current collector interface. If the annealing temperature is too low, Nafions cannot undergo sufficient microphase separation, thus failing to form ordered hydrophilic ion cluster channels, resulting in low ionic conductivity of the membrane and increased internal resistance of the battery. However, the annealing temperature cannot be too high either, otherwise the sulfonic acid groups in Nafions will undergo dehydration or degradation, and β-cyclodextrin is prone to carbonization or structural damage, causing the interfacial membrane to lose its ion selectivity function.
[0010] Ultrasonic oscillation can induce host-guest inclusion or interchain entanglement between the hydrophobic backbone of Nafion and the hydrophobic cavity of β-cyclodextrin, forming a uniform milky white or transparent dispersion. If the ultrasonic time is too short, tiny suspended particles are still visible in the solution, indicating that the hydrophobic backbone of Nafion has not completely entered the β-cyclodextrin cavity, failing to form an effective interpenetrating network structure. This results in an inhomogeneous membrane microstructure, leading to excessively high local current density, which easily induces lithium dendrite growth and reduces battery cycle life. Conversely, if the ultrasonic time is too long, prolonged high-energy ultrasound may cause excessively high local temperatures or physical breakage of the polymer chains, not only wasting energy but also potentially damaging the already formed supramolecular assembly structure, leading to a decrease in the mechanical toughness of the final membrane.
[0011] As a preferred embodiment of the lithium-ion battery negative electrode current collector preparation method of the present invention, the preparation method of the β-cyclodextrin and Nafion composite solution in step S2 includes the following steps: S1. Coat the surface of copper foil with a composite solution of β-cyclodextrin and Nafion; S2. Pre-dry the coated copper foil; S3. The pre-dried copper foil is annealed at high temperature.
[0012] The composite solution prepared by this specific process enables β-cyclodextrin and Nafion to be uniformly mixed at the molecular level, which helps to form a composite coating with uniform composition and few defects on the copper foil surface, thereby ensuring the stability and selectivity of ion sieve layering.
[0013] In a preferred embodiment of the lithium-ion battery negative electrode current collector preparation method of the present invention, the total concentration of β-cyclodextrin and Nafion in solution A is 0.002~0.01 g / mL.
[0014] In a preferred embodiment of the lithium-ion battery negative electrode current collector preparation method of the present invention, the ultrasonic oscillation power is 100~300 W and the frequency is 20~40 kHz, preferably 400 W and 30 kHz. Ultrasonic treatment under these specific conditions can effectively break down intermolecular aggregates, ensuring uniform dispersion of β-cyclodextrin and Nafion, forming a stable composite system.
[0015] In a preferred embodiment of the lithium-ion battery negative electrode current collector preparation method of the present invention, the pre-drying temperature is 50~70℃ and the drying time is 1.5~2.5 h, preferably 60℃ and 2 h.
[0016] In a preferred embodiment of the lithium-ion battery negative electrode current collector preparation method of the present invention, the high-temperature annealing time in step S3 is 10~14 h, preferably 12 h.
[0017] In a preferred embodiment of the method for preparing the negative electrode current collector of the lithium-ion battery according to the present invention, the thickness of the β-cyclodextrin and Nafion composite solution coated in step S1 is 20~30 μm. A coating thickness less than 20 μm has no significant effect on improving the lithium-ion conductivity at the current collector interface; a coating thickness greater than 30 μm will result in an excessively thick interfacial film, thus blocking the passage of lithium ions and increasing internal resistance.
[0018] A preferred embodiment of the method for preparing the negative electrode current collector of the lithium-ion battery according to the present invention further includes pretreatment of the copper foil before coating with the β-cyclodextrin and Nafion composite solution. The pretreatment includes cleaning with anhydrous ethanol, acid washing with dilute hydrochloric acid, rinsing with water, and drying. Single-ion conductors have higher requirements for interfacial contact; acid washing can thoroughly remove the surface oxide layer and increase the adhesion of the interfacial film to the copper foil.
[0019] Secondly, the present invention provides a lithium-ion battery negative electrode current collector, which is prepared by the above-mentioned lithium-ion battery negative electrode current collector preparation method.
[0020] Thirdly, the present invention provides a lithium-ion battery, including the aforementioned lithium-ion battery negative electrode current collector.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention utilizes the dual mechanisms of "pore size sieving" and "Donnan electrostatic repulsion" to transform the negative electrode current collector interface of lithium-ion batteries into an approximately ideal single-ion conductor, thereby achieving uniform and rapid deposition of lithium ions and significantly improving the cycle life and safety of the battery. Attached Figure Description
[0022] Figure 1 The surface morphology of the copper foil coated with the β-cyclodextrin and Nafion interfacial film is shown in the figure, namely Cu@Nafion@β-CD. Figure 2 The image shows the surface morphology of the uncoated copper foil, represented by Cu. Detailed Implementation
[0023] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.
[0024] Unless otherwise specified, all other materials and reagents used in the examples are commercially available.
[0025] Examples 1-11 and Comparative Examples 1-11 The preparation methods of lithium-ion negative electrode current collectors in Examples 1-11 and Comparative Examples 1-11 are as follows: S1. Cut copper foil to 10 cm × 10 cm, first ultrasonically clean it with anhydrous ethanol for 5 minutes; then immerse it in 1M dilute hydrochloric acid solution for 1 minute; finally rinse it with deionized water and put it in a vacuum drying oven for later use.
[0026] S2. Prepare a composite solution of cyclosporine and binder.
[0027] S3. Using a wire rod coater or doctor blade, uniformly coat the prepared cyclosporine and binder composite solution onto the pretreated copper foil surface. Control the wet film thickness to 20-30 μm.
[0028] S4. Place the coated copper foil into a vacuum drying oven and dry it at 60 ℃ for 2 h.
[0029] S5. Raise the temperature to T ℃ and perform vacuum heat annealing.
[0030] S6. After natural cooling, remove the composite current collector and cut it into circular electrode sheets with a diameter of 12 mm for use as negative electrode materials for lithium metal batteries.
[0031] The preparation method of the cyclosporine and binder composite solution in step S2 is as follows: S21. Mix anhydrous ethanol and deionized water at a volume ratio of 1:1 to prepare 10 mL of mixed solvent.
[0032] S22. Weigh out the cyclosporine and add it to the above solvent. Sonicate the solution in a 40 ℃ water bath for 10 min until the solution is clear and transparent to obtain the cyclosporine solution.
[0033] S23. Use a pipette to measure the adhesive and slowly add it dropwise into the cyclosporine solution to obtain a total concentration of ag / mL. S24. Sonicate solution A.
[0034] The composition and dosage of lithium-ion anode current collectors in Examples 1-11 and Comparative Examples 1-11, the thermal annealing temperature T, the thermal annealing time t2, the ultrasonic oscillation time t1 of solution A, the ultrasonic oscillation frequency and power, and the concentration a of solution A are shown in Table 1.
[0035] The current collector interface ion transfer numbers of Examples 1-11 and Comparative Examples 1-11 were tested respectively, and the test results are shown in Table 2.
[0036] Table 1 Table 2 As can be seen from Tables 1 and 2, the current collectors prepared in Examples 1-11 have high surface mobility numbers. Figure 1 The image shows the SEM morphology of the current collector prepared in Example 1. Figure 2 This is a SEM image of the uncoated copper foil.
[0037] Comparing Examples 1-3 with Comparative Examples 1-2, it was found that the change in the component ratio in solution A affects the material properties. The experimental results show that when the ratio of β-cyclodextrin to Nafion is 2:1 to 6:1, the ion transference number on the surface of the current collector is higher.
[0038] Comparing Examples 1, 4-5 and Comparative Examples 3-4, it was found that the change in heat annealing temperature affects the material properties. The experimental results show that when the heat annealing temperature is between 80 and 120 °C, the ion migration number on the surface of the current collector is relatively high.
[0039] Comparing Examples 1, 6-7 and Comparative Examples 5-6, it was found that the time variation of ultrasonic oscillation of solution A affects the material properties. The experimental results show that when the ultrasonic oscillation time is between 10 and 60 min, the ion transference number on the surface of the current collector is relatively high.
[0040] Comparing Example 1 with Comparative Examples 7 and 10-11 revealed the impact of β-cyclodextrin on material properties. Comparative Example 7 used only Nafion to prepare the current collector interface film, and the experimental results showed a low lithium-ion transference number. This is because although Nafion possesses the Donnan electrostatic repulsion effect of sulfonic acid groups, it lacks the physical pore size sieving of β-cyclodextrin, thus failing to form single-ion channels. Furthermore, the pure Nafion film swelled significantly in the organic electrolyte, exhibiting weak mechanical dendrite-blocking ability. In contrast, Lithium Examples 10-11 used α-cyclodextrin (approximately 0.47-0.53 nm) with smaller pore sizes and γ-cyclodextrin (approximately 0.75-0.83 nm) with larger pore sizes to prepare current collector interface films with Nafion, respectively. The experimental results showed a low ion transference number. This is because the small pore size of α-cyclodextrin hinders lithium-ion transport and prevents effective assembly with Nafion, resulting in poor mechanical properties and a significant decrease in conductivity of the current collector interface film. γ-cyclodextrin, with its larger pore size, cannot effectively block some of the incompletely desolvated anionic clusters. Neither of these two is as well-matched to the lithium-ion size and Nafion chain as β-cyclodextrin (approximately 0.6-0.78 nm).
[0041] Comparing Example 1 with Comparative Examples 8-9 revealed the impact of Nafion on material properties. Comparative Example 8 used β-cyclodextrin and the inert binder PVDF to prepare a current collector interface film. Experimental results showed a low ion transference number. This is because the system only exhibits the physical sieving effect of β-cyclodextrin, lacking the electrostatic repulsion of Nafion. Furthermore, since PVDF cannot form a specific hydrophobic host-guest inclusion complex with β-cyclodextrin like Nafion, the uniformity of the interface film and the continuity of ion channels are poor, resulting in poor ion screening ability. Comparative Example 9 used sulfonated polystyrene, which also has negatively charged sulfonic acid groups, and β-cyclodextrin to prepare a current collector interface film. Experimental results showed a low ion transference number. This is because although sulfonated polystyrene also contains sulfonic acid groups, its main chain structure differs from the perfluorocarbon chain of Nafion, making it difficult to form a matching "host-guest" inclusion structure with the hydrophobic cavities of β-cyclodextrin. This makes it difficult for β-cyclodextrin to effectively adhere to the copper foil surface, thus failing to perform ion screening.
[0042] Comparing Example 1 with Example 8, it can be concluded that the surface ion transference number of the current collector prepared with a solution ultrasonic oscillation frequency within the range of the present invention is higher.
[0043] Comparing Example 1 with Example 9, it can be concluded that the surface ion transference number of the current collector prepared with ultrasonic oscillation power within the range of the present invention is relatively high.
[0044] Comparing Example 1 with Examples 10-11, it can be concluded that the current collector surface ion transfer number is higher when the heat annealing time is within the range of the present invention, and the effect is best when the heat annealing time is 12 h.
[0045] from Figure 1 It can be seen that the β-cyclodextrin and Nafion current collector interface film prepared by the present invention has good film-forming properties and is uniformly adhered to the copper foil surface.
[0046] Example of effect This example examines the coulombic efficiency of a lithium-copper (Li||Cu) half-cell incorporating the current collector of this invention. The current collectors prepared in Example 1, Comparative Example 7, and the blank sample (bare copper foil) were used as the working electrode, and a lithium metal sheet as the counter electrode. A CR2032 coin cell was assembled using a mixed solvent (1:1 volume ratio) of 1.0 M LiPF6 dissolved in dimethyl ethylene glycol (DME) and 1,3-dioxane (DOL), with 2.0 wt% LiNO3 added as an additive as the electrolyte. Celgard 2500 was used as the separator. The constant current charge-discharge cycle performance of the cell was tested at a current density of 1 mA cm⁻² and a deposition areal capacity of 1 mAh cm⁻², and the changes in coulombic efficiency were recorded. The test results are shown in Table 3.
[0047] Table 3 As can be seen from Table 3, β-cyclodextrin / Nafion has good single-ion conductor properties, which can significantly improve the coulombic efficiency and stabilize it at a relatively long number of cycles.
[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a negative electrode current collector for a lithium-ion battery, characterized in that, Includes the following steps: S1. Coat the surface of copper foil with a composite solution of β-cyclodextrin and Nafion; S2. Vacuum pre-dry the coated copper foil; S3. Vacuum high-temperature annealing is performed on the pre-dried copper foil; The vacuum high-temperature annealing temperature in step S3 is 80~120℃; The method for preparing the β-cyclodextrin and Nafion complex solution includes preparing an aqueous solution of β-cyclodextrin and Nafion and then ultrasonically vibrating it; wherein the mass ratio of β-cyclodextrin to Nafion is 2:1 to 6:1; and the ultrasonic vibration time is 10 to 60 min.
2. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 1, characterized in that, The preparation method of the β-cyclodextrin and Nafion complex solution includes the following steps: S11. Add β-cyclodextrin to an aqueous ethanol solution to obtain a β-cyclodextrin solution; S12. Slowly add Nafion dispersion to the β-cyclodextrin solution to obtain solution A; S13. Sonicate solution A.
3. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 2, characterized in that, The total concentration of β-cyclodextrin and Nafion in solution A is 0.002~0.01 g / mL.
4. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 2, characterized in that, The ultrasonic oscillation has a power of 100~300 W and a frequency of 20~40 kHz.
5. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 1, characterized in that, The pre-drying temperature is 50~70℃, and the drying time is 1.5~2.5 h.
6. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 1, characterized in that, The high-temperature annealing time in step S3 is 10~14 h.
7. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 1, characterized in that, The thickness of the β-cyclodextrin and Nafion composite solution coated in step S1 is 20~30 μm.
8. The method for preparing the negative electrode current collector of a lithium-ion battery as described in claim 1, characterized in that, It also includes pretreatment of the copper foil before coating with the β-cyclodextrin and Nafion composite solution, the pretreatment including cleaning with anhydrous ethanol, acid washing with dilute hydrochloric acid, washing with water, and drying.
9. A negative electrode current collector for a lithium-ion battery, characterized in that, The lithium-ion battery negative electrode current collector is prepared by the method described in any one of claims 1 to 8.
10. A lithium-ion battery, characterized in that, Includes the lithium-ion battery negative electrode current collector as described in claim 9.