Cerium oxide doped zinc oxide composite functional current collector and preparation method and application thereof

Abstract

The invention provides a cerium oxide-doped zinc oxide composite functional current collector and a preparation method and application thereof, and relates to the technical field of lithium metal battery negative electrode current collectors. The cerium oxide doped zinc oxide composite functionalized current collector is composed of a copper foil substrate, a zinc oxide nanosheet layer and a cerium oxide doped layer, zinc oxide nanosheets grow on the surface of a copper foil in situ through an electroplating method, and cerium oxide is doped into zinc oxide lattices through a chemical bath method. The zinc oxide nanosheet is rapidly prepared on the surface of the copper foil and cerium oxide doping is carried out, so that the lithium affinity of the material is remarkably improved, the problem of heterogeneous lithium nucleation is inhibited, the problem of out-of-control growth of dendrites caused by local high current density is effectively relieved, the point effect of lithium dendrites is inhibited, non-uniform deposition is reduced, and the growth of the lithium dendrites is further inhibited; and the SEI fracture problem caused by volume fluctuation in the cycle process is effectively inhibited, so that the service life of the battery is prolonged, and the method is suitable for constructing the lithium metal battery with high energy density and long cycle life.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery negative electrode current collector technology, and in particular to a cerium oxide-doped zinc oxide composite functionalized current collector, its preparation method and application. Background Technology

[0002] Energy storage technology has become a vital force driving social progress, with widespread applications in daily life and various energy storage fields. However, the energy density of traditional lithium-ion batteries (LIBs) is nearing its theoretical capacity limit, failing to meet market demands for higher energy densities. In contrast, lithium metal batteries (LMBs), using metallic lithium as the negative electrode, boast high theoretical capacity and low electrochemical potential. This fundamental difference makes LMBs an indispensable material for emerging applications such as electric aviation and grid-scale energy storage.

[0003] However, the practical application of LMB faces two fundamental problems: First, heterogeneous lithium nucleation and localized high current density lead to uncontrolled dendrite growth, resulting in short circuits and thermal runaway; second, infinite volume fluctuations during cycling cause the solid electrolyte interphase (SEI) to break down, leading to continuous electrolyte depletion and low coulombic efficiency (the coulombic efficiency of conventional carbonate electrolytes is <90%). Although advanced electrolyte and artificial SEI designs have shown initial success, the inherent lithium affinity and insufficient topological orientation of planar current collectors (such as copper foil) remain the root causes of these failures.

[0004] Therefore, achieving stable lithium metal batteries and inducing controllable lithium deposition behavior are crucial for developing high-energy-density batteries. Summary of the Invention

[0005] In view of this, the present invention provides a cerium oxide-doped zinc oxide composite functionalized current collector, its preparation method, and its application. The present invention significantly improves the lithiophilicity of the material by rapidly preparing zinc oxide nanosheets on a copper foil surface and then doping them with cerium oxide, suppressing the problem of heterogeneous lithium nucleation, effectively alleviating the problem of uncontrolled dendrite growth caused by local high current density, suppressing the tip effect of lithium dendrites, reducing uneven deposition, further suppressing lithium dendrite growth, and effectively suppressing the SEI cracking problem caused by volume fluctuations during cycling, thereby improving battery life. This invention is suitable for constructing lithium metal batteries with high energy density and long cycle life.

[0006] The first aspect of this invention is a cerium oxide-doped zinc oxide composite functionalized current collector (CeO2-ZnO@Cu), wherein the functionalized current collector comprises a copper foil substrate, a zinc oxide nanosheet layer, and a cerium oxide (CeO2) doped layer. The zinc oxide nanosheets are grown in situ on the copper foil surface by electroplating, and the cerium oxide is doped into the zinc oxide lattice by a chemical bath method. The oxygen vacancies of the CeO2 contain Ce. 3+ / Ce4+ Redox pair, capable of adsorbing Li + It also promotes uniform distribution of local charges and reduces the nucleation barrier.

[0007] A second aspect of the present invention is to provide a method for preparing the above-mentioned cerium oxide-doped zinc oxide composite functionalized current collector, comprising the following steps: S1. Copper foil surface pretreatment: The copper foil is immersed in dilute hydrochloric acid, acetone and ethanol in sequence for ultrasonic cleaning to remove surface oil and impurities; S2. Preparation of zinc oxide nanosheets: Pretreated copper foil was used as the working electrode, stainless steel sheet as the counter electrode, and saturated calomel electrode as the reference electrode. Constant current electroplating was carried out in an electrolyte containing ZnSO4, ammonium persulfate and NaOH. After rinsing with deionized water and drying, ZnO@Cu was obtained. S3, Cerium oxide doping: ZnO@Cu is immersed in dilute hydrochloric acid for surface activation, then immersed in Ce(NO3)4 solution for a second time, rinsed with deionized water and dried, and then heated and annealed to finally obtain cerium oxide doped zinc oxide composite current collector CeO2-ZnO@Cu.

[0008] Preferably, in step S1, the copper foil thickness is 6-50 μm, and the dilute hydrochloric acid concentration is 0.05-0.2 mol / L. -1 The ultrasonic cleaning time is 5 minutes.

[0009] Preferably, in step S2, the electrolyte includes 0.1-3 M ZnSO4, 0.1-0.5 M ammonium persulfate, and 0.02-0.1 M NaOH.

[0010] Preferably, in step S2, the current density of the constant current electroplating is -5 to -10 mA·cm⁻¹. -2 The electroplating time is 100-900 s.

[0011] Preferably, in step S3, the Ce(NO3)4 solution concentration is 0.01-0.5 M, the pH is adjusted to 2-9 with dilute nitric acid, the first soaking time is 5-10 s, and the second soaking time is 0.5-4 h.

[0012] Preferably, in step S3, the heating rate of the heating annealing is 1-10℃ / min, the heating annealing temperature is 250-500℃, more preferably 250℃-500℃, and the heating annealing holding time is 0.5-4 h.

[0013] A third aspect of this invention is to provide the application of the above-mentioned cerium oxide-doped zinc oxide composite functionalized current collector in a lithium metal battery. The functionalized current collector is used to guide uniform lithium deposition, suppress lithium dendrite growth, and improve the cycle stability and coulombic efficiency of the lithium metal battery. The lithium metal battery operates at 1 mA·cm⁻¹. -2 and 1 mAh·cm -2 Under these conditions, the coulombic efficiency remains above 95%, and the cycle life exceeds 200 cycles, making it suitable for operating conditions with high current density and high deposition capacity.

[0014] Preferably, the lithium metal battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The negative electrode uses the aforementioned functionalized current collector as the negative electrode current collector. The functionalized current collector is used to guide uniform lithium deposition, suppress lithium dendrite growth, and improve the cycle stability and coulombic efficiency of the lithium metal battery.

[0015] Preferably, the electrolyte is an ether-based or ester-based electrolyte, more preferably an electrolyte containing LiFSI and LiNO3, and even more preferably, the electrolyte is an ether-based electrolyte of 1M LiFSI and 1% LiNO3.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention significantly improves the lithiophilicity of zinc oxide nanosheets by rapidly preparing them on copper foil and then doping them with cerium oxide, effectively solving the problems of insufficient lithiophilicity and topological orientation of planar current collectors; CeO2 oxygen vacancies contain Ce. 3+ / Ce 4+ Redox pair, capable of adsorbing Li + It promotes uniform local charge distribution, further reducing the nucleation barrier and thus suppressing heterogeneous lithium nucleation. The oxygen vacancies in CeO2, combined with the semiconductor properties of ZnO, enhance interfacial ion / electron conduction, guiding uniform lithium deposition and effectively mitigating the runaway dendrite growth problem caused by localized high current density. The high dielectric constant of CeO2 can alleviate local electric field distortion and suppress the tip effect of lithium dendrites. 3+ / Ce 4+ Dynamic redox can consume free Li + This reduces uneven deposition and further suppresses lithium dendrite growth. Through the synergistic effect of the above mechanisms, this invention effectively suppresses SEI cracking caused by volume fluctuations during cycling, thereby improving battery lifespan.

[0017] The functionalized current collector prepared in this invention can withstand high current densities (>1 mA·cm). -2 ) and high deposition capacity (>1mAh·cm) -2Under these conditions, lithium metal batteries using this current collector can still provide high coulombic efficiency (>95%) and a cycle life of over 200 cycles, making them suitable for building lithium metal batteries with high energy density and long cycle life. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a flowchart illustrating the preparation process of the high-performance functionalized current collector of this invention. Figure 2 The XPS energy spectrum of the CeO2-ZnO@Cu current collector in Example 1 of this invention; Figure 3 The image shows the XRD pattern of the CeO2-ZnO@Cu current collector in Example 1 of this invention, where the left image is the complete XRD pattern and the right image is a magnified view of a portion thereof. Figure 4 For 1, 2, 4 and 8 mAh·cm -2 SEM images of lithium deposition morphology under different deposition capacities, from top to bottom, show a comparison of the lithium deposition surface morphology on three current collectors: Cu foil, ZnO@Cu, and CeO2-ZnO@Cu. Figure 5 For 1 mA·cm -2 and 1 mAh·cm -2 The coulombic efficiency of three current collectors (Cu foil, ZnO@Cu, CeO2-ZnO@Cu) varies with the number of cycles under the specified conditions; Figure 6 SEM images of the cross-sectional deposition morphology of lithium on different current collectors are shown, where (a) is the cross-sectional morphology of the lithium deposition layer with a thickness of 27.36 μm on Cu foil, and (b) is the cross-sectional morphology of the lithium deposition layer with a thickness of 19 μm on CeO2-ZnO@Cu. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all experiments were repeated three times. Results are expressed as mean ± standard deviation, and P < 0.05 indicates a significant difference.

[0022] Example 1: A method for preparing a CeO2-ZnO@Cu current collector, the steps of which are as follows: S1. Copper foil surface pretreatment: 11 μm thick copper foil is sequentially immersed in a solution with a concentration of 0.1 mol / L. -1 The surface oil and impurities were removed by ultrasonic cleaning for 5 minutes in dilute hydrochloric acid, acetone and ethanol, respectively. S2, Preparation of Zinc Oxide Nanosheets: Copper foil pretreated with S1 was used as the working electrode, a stainless steel sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The nanosheets were placed in an electrolyte consisting of 0.2 M ZnSO4 + 0.1 M ammonium persulfate + 0.02 M NaOH and subjected to a constant current of -10 mA·cm⁻¹. -2 Electroplating for 300 s, rinsing with deionized water, and drying at 60℃ yields ZnO@Cu; S3, Cerium oxide doping: ZnO@Cu from S2 was immersed in dilute hydrochloric acid for 5 s for surface activation, and then placed in a Ce(NO3)4 solution with a pH of 6 and a concentration of 0.02 M for 1 h at room temperature. After rinsing with deionized water and drying, the sample was placed in a muffle furnace and heated to 300℃ at a rate of 5℃ / min and held for annealing for 1 h to obtain cerium oxide doped zinc oxide composite current collector CeO2-ZnO@Cu.

[0023] Example 2: A method for preparing a lithium metal battery using a CeO2-ZnO@Cu current collector, comprising the following steps: S1. Cut the CeO2-ZnO@Cu from Example 1 into 16 mm electrode sheets; S2. In an argon-filled glove box, assemble a half-cell (2032 coin cell), including a positive electrode shell, a negative electrode shell, a gasket, a spring, a lithium sheet, modified CeO2-ZnO@Cu, and a 1 M LiFSI+1% LiNO3 electrolyte, with the CeO2-ZnO side facing the lithium sheet.

[0024] S3. Allow the assembled battery to stand for 12 hours under the test environment. After standing, conduct the test under the following conditions: current density is fixed at 1 mA / cm². -2 The deposition amounts were 1 and 3 mAh·cm⁻¹, respectively. -2 .

[0025] Example 3 The difference from Example 2 is that the test condition is a current density of 0.5 mAcm. -2 The deposition amounts were 1, 2, 4, and 8 mAh·cm³, respectively. -2 After the cycle is completed, the battery is disassembled, the negative current collector is removed, rinsed with DME, dried and cut into appropriate sizes, and then subjected to SEM testing.

[0026] Comparative Example 1 The difference from Example 2 is that the current collector is a commercial copper foil with a thickness of 11 μm, and the electrode is cut from the commercial copper foil with the rough side of the copper foil facing the lithium sheet.

[0027] Comparative Example 2 The difference from Example 2 is that the current collector is ZnO@Cu from step S2 of Example 1, and the electrode is cut from modified ZnO@Cu with one ZnO side facing the lithium sheet.

[0028] Comparative Example 3 The difference from Example 2 is that the current collector is a commercially available copper foil with a thickness of 11 μm, and the electrode is cut from the commercially available copper foil with the rough side of the copper foil facing the lithium sheet; the test conditions are a current density of 0.5 mAcm. -2 The deposition amounts were 1, 2, 4, and 8 mAh·cm³, respectively. -2 After the cycle is completed, the battery is disassembled, the negative current collector is removed, rinsed with DME, dried and cut into appropriate sizes, and then subjected to SEM testing.

[0029] Comparative Example 4 The difference from Example 2 is that the current collector is ZnO@Cu from step S2 of Example 1, the electrode is cut from modified ZnO@Cu, and the ZnO side faces the lithium sheet; the test conditions are a current density of 0.5 mAcm⁻¹. -2 The deposition amounts were 1, 2, 4, and 8 mAh·cm⁻¹, respectively. -2 After the cycle is completed, the battery is disassembled, the negative current collector is removed, rinsed with DME, dried and cut into appropriate sizes, and then subjected to SEM testing.

[0030] from Figure 2 XPS energy dispersive spectroscopy analysis results show that the Ce 3d spectrum in the CeO2-ZnO@Cu current collector exhibits distinct characteristic peaks at 917 eV, 907.8 eV, 904.3 eV, 901 eV, 898.9 eV, 886.9 eV, 885.5 eV, and 882.9 eV, respectively. These peaks correspond to Ce... 3+ and Ce 4+ The electron binding energy indicates that Ce in cerium oxide 3+ and Ce 4+ The coexistence of these elements confirms the successful doping of cerium oxide and the formation of oxygen vacancies. The Zn 2p spectrum shows characteristic peaks of Zn 2p3 / 2 and Zn 2p1 / 2 at 1022.3 eV and 1045.5 eV, respectively, confirming the presence of zinc oxide. These results demonstrate the successful preparation of a cerium oxide-doped zinc oxide composite functionalized current collector according to this invention.

[0031] from Figure 3The XRD pattern analysis results show that Cu foil exhibits characteristic diffraction peaks of Cu (111), (200), and (220) near 2θ = 43°, 50°, and 74°. ZnO@Cu shows characteristic peaks of ZnO in addition to the characteristic peaks of Cu. The XRD pattern of CeO2-ZnO@Cu is basically consistent with that of ZnO@Cu. The magnified view near 2θ = 36.0° shows that the characteristic peak of ZnO (101) is clearly visible, confirming the successful preparation of ZnO nanosheets on the surface of copper foil. At the same time, the doping of CeO2 did not change the crystal structure of ZnO, indicating that CeO2 was successfully doped into the ZnO lattice rather than forming an independent crystal phase.

[0032] from Figure 4 The analysis results of lithium deposition morphology show that, with different deposition capacities (1, 2, 4 and 8 mAh·cm⁻¹), -2 Under these conditions, the three current collectors exhibited significantly different lithium deposition behaviors. For Cu foil, at 1 mAh·cm⁻¹… -2 Irregular lithium deposition morphology appeared on the lower surface with increasing deposition capacity to 2, 4, and 8 mAh·cm⁻¹. -2 The surface morphology exhibits obvious dendritic structures and pores, indicating uneven lithium deposition. For ZnO@Cu, at 1 and 2 mAh·cm⁻¹, -2 The lithium deposition on the lower surface is relatively uniform, but when the deposition capacity increases to 4 and 8 mAh·cm⁻¹, the deposition becomes more uniform. -2 Even at high deposition capacities, some degree of uneven deposition still occurs. In contrast, CeO2-ZnO@Cu exhibits a dense and uniform lithium deposition morphology across all deposition capacities, even at a high deposition capacity of 8 mAh·cm³. -2 The surface remains smooth, demonstrating that the functionalized current collector of the present invention can effectively guide uniform lithium deposition and suppress dendrite growth.

[0033] from Figure 5 The coulomb efficiency comparison analysis results show that at 1 mA·cm -2 and 1 mAh·cm -2 Under the test conditions, the cycling performance of the three current collectors showed significant differences. The coulombic efficiency of Cu foil was around 90% in the initial few cycles, but decreased rapidly, dropping to around 20% after about 50 cycles. ZnO@Cu initially had a coulombic efficiency above 90%, showing some improvement in cycling performance, but its stability remained insufficient, exhibiting a significant downward trend after about 100 cycles. In contrast, CeO2-ZnO@Cu maintained a stable coulombic efficiency above 95% throughout the entire test, showing no significant degradation even after more than 250 cycles, significantly outperforming the comparative example. This result fully demonstrates that the functionalized current collector constructed by cerium oxide-doped zinc oxide in this invention can effectively improve the cycling stability and coulombic efficiency of lithium metal batteries.

[0034] from Figure 6 The cross-sectional deposition morphology analysis results show that there are significant differences in the thickness and microstructure of the lithium deposition layer on different current collectors. On Cu foil, the lithium deposition layer thickness reaches 27.36 μm, and the cross-sectional morphology shows that the deposition layer is loose and porous, with numerous pores and cracks. In contrast, on CeO2-ZnO@Cu, the lithium deposition layer thickness is only 19 μm, which is about 30% less than that on Cu foil, and the cross-sectional morphology shows that the deposition layer is dense and uniform, tightly bonded to the current collector, and has almost no obvious pores and cracks. This result indicates that the functionalized current collector of the present invention can effectively reduce the deposition layer thickness and suppress lithium dendrite growth by improving lithium affinity and optimizing electric field distribution, thereby improving the volumetric energy density and cycle life of the battery.

[0035] In summary, the CeO2-ZnO@Cu functionalized current collector prepared in this invention utilizes the oxygen vacancies (CeO2-ZnO@Cu) in cerium oxide. 3+ / Ce 4+ Redox pairs) adsorbing Li + This process promotes uniform local charge distribution, enhances interfacial ion / electron conduction by combining the semiconductor properties of ZnO with the high dielectric constant of CeO2 to alleviate local electric field distortion, thus achieving effective control over lithium deposition behavior. Material characterization results confirm the successful preparation of the functionalized layer. Electrochemical testing results show that the current collector maintains excellent cycling stability (>95% coulombic efficiency, >250 cycles) even under high current density and high deposition capacity conditions. Morphology analysis confirms uniform and dense lithium deposition and dendrite suppression effects, fully validating the technical effectiveness and practical value of this invention.

[0036] Example 4 The difference from Example 1 is that the electroplating time in step S2 is changed to 600 s. The battery was assembled and tested according to the method of Example 2, with a current density of 1 mA / cm². 2 Deposition amount 1 mAh·cm -2 .

[0037] The results show that in this embodiment, when the electroplating time reaches 600 s, the zinc oxide nanosheets are more densely distributed, and at this time, the zinc oxide nanosheets are at a density of 1 mA cm⁻¹. -2 1 mAh·cm -2 Under these conditions, the battery only achieved stable cycling for 60 cycles, with CE remaining at 80.12%.

[0038] Example 5 The difference from Example 1 is that the annealing temperature in step S3 is changed to 400°C. The battery is assembled and tested according to the method of Example 2.

[0039] The results show that, in this embodiment, the CeO2 doping effect and the current collector performance decrease slightly at an annealing temperature of 400℃ compared to 300℃. At this temperature, the battery coulombic efficiency remains at 45.03% after 143 cycles.

[0040] Example 6 The difference from Example 2 is that the test condition is a current density of 1 mA / cm². 2 Deposition amount 1 mAh·cm -2 The number of cycles is greater than 250.

[0041] The results show that, although the number of cycles decreases with increasing current density, this embodiment can still cycle more stably than copper foil.

[0042] Example 7 The difference from Example 1 is that the soaking time in Ce(NO3)4 solution in step S3 is changed to 1.5 h. The battery is assembled and tested according to the method of Example 2.

[0043] The results show that when the Ce(NO3)4 solution soaking time is 1.5 h, the CeO2 doping effect decreases. At this time, the coulombic efficiency of the battery decreases significantly after 43 cycles, and after 54 cycles, the CE remains at 73.26%.

[0044] Comparative Example 5: Copper foil modified with CeO2 only The results show that the copper foil cannot be prepared alone because an ideal substrate requires a flat, pure, and structurally stable surface. However, copper foil is easily oxidized in aqueous chemical baths and at high temperatures, forming copper oxide layers with varying compositions. This severely hinders the epitaxial growth of CeO2 grains. Furthermore, CeO2 has a weak chemical affinity for copper, making it difficult to form strong chemical bonds at the atomic level. Without an intermediate transition layer to alleviate lattice mismatch and stress, directly deposited CeO2 films are prone to cracking or peeling due to excessive internal stress.

[0045] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A cerium oxide-doped zinc oxide composite functionalized current collector, comprising a copper foil substrate, zinc oxide nanosheets, and a cerium oxide-doped layer, characterized in that, Zinc oxide nanosheets are grown in situ on the surface of copper foil by electroplating, and cerium oxide is doped into the zinc oxide lattice by chemical bath method.

2. The preparation method of the cerium oxide-doped zinc oxide composite functionalized current collector according to claim 1, characterized in that, Includes the following steps: S1. Copper foil surface pretreatment to remove surface oil and impurities; S2, Preparation of zinc oxide nanosheets: Using copper foil pretreated with S1 as the working electrode, constant current electroplating was performed in an electrolyte containing ZnSO4, ammonium persulfate and NaOH to obtain ZnO@Cu; S3, Cerium oxide doping: After activating the ZnO@Cu surface of S2, it is immersed in Ce(NO3)4 solution and then annealed by heating to obtain cerium oxide doped zinc oxide composite current collector.

3. The preparation method according to claim 2, characterized in that, In step S1, the copper foil surface pretreatment method is as follows: the copper foil is immersed in dilute hydrochloric acid, acetone and ethanol in sequence for ultrasonic cleaning to remove surface oil and impurities.

4. The preparation method according to claim 2, characterized in that, In step S2, the electrolyte comprises 0.1-3M ZnSO4, 0.1-0.5M ammonium persulfate, and 0.02-0.1M NaOH.

5. The preparation method according to claim 2, characterized in that, In step S2, the current density of the constant current electroplating is -5 to -10 mA·cm. -2 The electroplating time is 100-900 s.

6. The preparation method according to claim 2, characterized in that, In step S3, the concentration of the Ce(NO3)4 solution is 0.01-0.5 M, and the pH is 2-9.

7. The preparation method according to claim 2, characterized in that, In step S3, the soaking time is 0.5-4 hours.

8. The preparation method according to claim 2, characterized in that, In step S3, the heating rate of the heating annealing is 1-10℃ / min, the heating annealing temperature is 250-500℃, and the holding time of the heating annealing is 0.5-4 h.

9. The application of the cerium oxide-doped zinc oxide composite functionalized current collector prepared by the method of any one of claims 1 or 2-8 as a negative electrode current collector in lithium metal batteries.

10. The application according to claim 9, characterized in that, The lithium metal battery also includes a positive electrode, a negative electrode, a separator, and an electrolyte.

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