High-entropy interface modified lithium metal negative electrode as well as preparation method and application thereof

Abstract

The invention provides a high-entropy interface modified lithium metal negative electrode as well as a preparation method and application thereof, and belongs to the technical field of lithium metal batteries. The lithium metal negative electrode is modified with the (ABCD) xSiyO high-entropy oxide, the characteristic that the high-entropy oxide layer has multiple components is used, uniform deposition of lithium is induced through the synergistic effect of all the components, the conductivity is improved, and the problems related to poor cycling stability and the safety problem can be effectively solved. In addition, the modification material is rich in source and small in environmental pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium metal batteries, and particularly relates to a lithium metal negative electrode modified with a high-entropy interface, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of social technology, people's demand for high-safety and high-specific-energy batteries is becoming increasingly strong. The lithium metal negative electrode has an extremely high theoretical specific capacity (3860 mAh / g) and an extremely low redox potential (-3.045 V vs. Li / Li + ), making it an ideal choice for the negative electrode material of high-energy-density rechargeable batteries. However, the lithium negative electrode faces the problem of uncontrolled Li dendrite growth caused by uneven electric field distribution and nucleation sites. Lithium dendrites can lead to continuous consumption of liquid electrolyte and active Li, increased interfacial resistance, and a significant reduction in Coulombic efficiency. More seriously, the continuous vertical growth of lithium dendrites will pierce the separator, ultimately triggering short circuits and thermal runaway of lithium metal batteries, posing great safety problems. Therefore, there is an urgent need to develop lithium metal negative electrodes with high theoretical capacity, high safety, and high stability.

[0003] High-entropy oxides are a new type of material that has emerged in recent years, opening up new avenues for the design of material composition and properties. High-entropy oxides are composed of 5 or more components, reducing the dependence on any single key metal source, and are diverse and controllable in both composition and structure. These materials exhibit a series of effects, including high entropy, lattice distortion, hysteretic diffusion, and the cocktail effect. Thanks to these four effects, high-entropy oxides exhibit excellent electrochemical performance, good corrosion resistance, and high mechanical strength, capable of overcoming the limitations of traditional electrodes and providing a new perspective for the development of negative electrode materials. However, the high reactivity of the lithium metal negative electrode makes it difficult to combine with high-entropy oxides. Summary of the Invention

[0004] Aiming at the problems existing in the background art, the purpose of the present invention is to provide a lithium metal negative electrode modified with a high-entropy interface, a preparation method thereof, and an application thereof. The present invention modifies (CuCoMnAu) x Si y O high-entropy oxide on the lithium metal negative electrode to improve the safety and cycle life of lithium metal batteries.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] A lithium metal negative electrode modified with a high-entropy interface, the lithium metal negative electrode includes a copper foil, a high-entropy oxide layer attached to the surface of the copper foil, and a lithium metal attached to the high-entropy oxide layer; the structural formula of the high-entropy oxide layer is (ABCD) x Si yO, and the four elements A, B, C, and D are different; among them, A is any one of Ag, Cu, Ni, and Al; B is any one of Cr, Mn, Fe, and Co; C is any one of V, Mg, Mn, and Mo; D is any one of Zn, Au, Sn, and In.

[0007] Furthermore, the thickness of the copper foil is 10 - 40 μm, and the thickness of the high-entropy oxide layer is 30 - 80 nm.

[0008] The present invention also provides a method for preparing the high-entropy interface-modified lithium metal negative electrode, comprising the following steps:

[0009] Step 1: Prepare a high-entropy target, which is a high-entropy alloy composed of four different elements A, B, C, and D in a molar ratio of a:b:c:d;

[0010] Step 2: Clean the copper foil and dry it;

[0011] Step 3: Use dual-source magnetron sputtering. Taking the copper foil cleaned in Step 2 as the sputtering substrate, and the high-entropy target obtained in Step 1 and the SiO2 target as the sputtering targets, magnetron co-sputtering is used to prepare a (ABCD) x Si y O high-entropy oxide layer on the surface of the copper foil;

[0012] Step 4: Use the copper foil with the high-entropy oxide layer obtained in Step 3 as the positive electrode, a lithium sheet as the negative electrode, and use a blue electrochemical workstation. By means of discharging, Li is deposited on the surface of the high-entropy oxide layer. After the deposition is completed, the copper foil is taken out, and the required high-entropy interface-modified lithium metal negative electrode is obtained.

[0013] Furthermore, in the high-entropy target of Step 1, the values of the molar ratios of the four elements are 0 < a ≤ 9, 0 < b ≤ 9, 0 < c ≤ 9, 0 < d ≤ 9.

[0014] Furthermore, a:b:c:d is preferably 1:1:1:1.

[0015] Furthermore, in Step 3, the process parameters of magnetron co-sputtering are: the sputtering temperature range is 20 °C to 100 °C, the sputtering power range is 5 W to 150 W, the background vacuum range is 4×10 -4 Pa to 2×10 -4 Pa, the process vacuum range is 0.5 Pa to 1.5 Pa, the distance from the target to the substrate material range is 6 cm to 10 cm; the argon gas flow rate range is 50 sccm to 150 sccm; the substrate rotation speed range is 5 r·min-1 to 10 r·min-1.

[0016] Furthermore, in Step 4, the process parameters of electroplating are: the current density and the electrodeposition time are determined according to the ratio of the capacity of the positive electrode to the capacity of the negative electrode.

[0017] The present invention also provides an application of the above lithium metal anode modified with a high-entropy interface in a lithium metal battery.

[0018] The mechanism of the present invention is as follows:

[0019] High-entropy oxide (ABCD) x Si y In O, the A source increases the conductivity, and the B source and C source are electrochemically active components. When undergoing a conversion reaction with lithium, they help reduce lattice deformation and stress accumulation, which is beneficial for achieving good toughness characteristics of the interfacial film. In addition, the "entropy stabilization effect" can maintain the lattice structure stability and overcome the challenges faced by traditional transition metal oxide anode materials, such as crystal structure changes and significant volume changes. D is a lithiumophilic metal, and the addition of the D source can induce uniform deposition of Li metal and reduce the growth of lithium dendrites. The addition of structurally stable silicon oxide can bind the multi-component high-entropy alloy to the surface of the copper current collector, preventing the powdering and shedding of the high-entropy alloy components during long-term cycling, enabling the modified layer to continuously and stably promote the battery performance. The present invention (ABCD) x Si y The design of the (ABCD)Si O modified layer gives full play to the characteristics of multi-components of the high-entropy oxide. Nanoscale high-entropy alloy particles and silicon oxide particles are uniformly distributed and tightly bonded to the substrate copper foil by means of magnetron sputtering. The thickness of the modified layer can be as thin as 30 nm, and the synergistic effect of each component improves the cycle reversibility and safety of the lithium metal battery.

[0020] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0021] The present invention uses a high-entropy oxide layer with the characteristics of multi-components. Through the synergistic effect of each component, it induces uniform deposition of lithium, increases the conductivity, and can effectively solve the problems related to poor cycle stability and safety problems. In addition, the modified material has rich sources and little environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. is a schematic diagram of dual-source magnetron sputtering. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the embodiments and the drawings.

[0024] Example 1

[0025] A preparation method of a lithium metal anode modified with a high-entropy interface includes the following steps:

[0026] Step 1: Prepare a high-entropy target, which is a high-entropy alloy composed of four elements, Cu, Co, Mn, and Au, in a molar ratio of 1:1:1:1.

[0027] Step 2: Cut the Cu foil into pieces with a size of 5 cm × 5 cm, and ultrasonically clean them with acetone, ethanol, and deionized water respectively. Ultrasonic cleaning is carried out for 10 minutes in each process to remove the oil stains and impurity particles on the surface of the cut Cu foil. Place the cleaned substrate in a blast drying oven at 80 °C to dry the residual water on its surface.

[0028] Step 3: Fix the dried substrate to the substrate holder, install the high-entropy alloy target and the SiO2 target at the target positions, adjust the direction of the sputtering target positions to make the targets face the substrate directly, seal the sputtering chamber, the distance between the target and the Cu substrate ranges from 8 cm, and the background vacuum is 2×10 -4 Pa; Turn on the revolution switch, the substrate rotation speed is 8 r·min -1 , after ignition, close the baffle, and pre-sputter for 30 minutes to remove the impurity particles on the surface of the target; The schematic diagram of dual-source magnetron sputtering is as Figure 1 shown;

[0029] Step 4: Formally sputter to prepare a (CuCoMnAu) x Si y O high-entropy oxide layer. The sputtering temperature is 25 °C, the sputtering power of the high-entropy alloy target is 20 W, the sputtering power of the SiO2 target is 150 W, the process vacuum is 0.5 Pa, the argon gas flow rate is 100 sccm, and the substrate rotation speed is 8 r min -1 , and the sputtering time is 15 minutes; After sputtering, take out the Cu foil;

[0030] Step 5: Use the copper foil with a high-entropy oxide layer obtained in Step 4 as the positive electrode, and a lithium sheet with a diameter of 16 mm and a thickness of 1.2 mm as the negative electrode. Use the BlueTEC system. If the ratio of the capacity (p) of the positive electrode to the capacity (n) of the negative electrode is 2, then at this time, 2 mAh / cm 2 of lithium needs to be deposited on the surface of the high-entropy oxide layer. Therefore, Li is deposited on the surface of the high-entropy oxide layer by discharging, the current density is 0.2 mA / cm 2 , discharge for 10 hours, take out the copper foil after deposition, and the desired lithium metal negative electrode with high-entropy interface modification is obtained.

[0031] The present invention also provides the application of the above-mentioned lithium metal negative electrode with high-entropy interface modification in a lithium metal battery, specifically: using LCO as the positive electrode, the electrolyte is 1M LiPF6 in DEC:EC = 1:1 wt% with 10% FEC, the separator uses PP2500, and combining with the lithium metal negative electrode with high-entropy interface modification to assemble a lithium metal battery.

[0032] Example 2

[0033] Step 1: Prepare a high-entropy target, which is a high-entropy alloy composed of four elements, Cu, Cr, Mn, and Sn, in a molar ratio of 1:1:1:1.

[0034] Step 2: Cut the Cu foil into pieces of 5 cm × 5 cm, and ultrasonically clean them with acetone, ethanol, and deionized water respectively for 10 min in each process to remove the oil stains and impurity particles on the surface of the Cu foil; place the cleaned substrate in a blast drying oven at 80 °C to dry the residual water on its surface.

[0035] Step 3: Fix the dried substrate on the substrate holder, install the high-entropy alloy target and the SiO2 target at the target positions, adjust the direction of the sputtering target positions to make the targets face the substrate directly, seal the sputtering chamber, the distance between the target and the Cu substrate ranges from 8 cm, and the background vacuum is 2×10 -4 Pa; turn on the revolution switch, the substrate rotation speed is 8 r min -1 , after starting the glow, close the baffle, and pre-sputter for 30 min to remove the impurity particles on the surface of the target.

[0036] Step 4: Formally sputter to prepare a (CuCrMnSn) x Si y O high-entropy oxide layer. The sputtering temperature is 25 °C, the sputtering power of the high-entropy alloy target is 20 W, the sputtering power of the SiO2 target is 150 W, the process vacuum is 0.5 Pa, the argon gas flow rate is 100 sccm, and the substrate rotation speed is 8 r min -1 , and the sputtering time is 5 min; take out the Cu foil after sputtering.

[0037] Step 5: Use the copper foil with the high-entropy oxide layer obtained in Step 4 as the positive electrode, use a lithium sheet with a diameter of 16 mm and a thickness of 1.2 mm as the negative electrode, use a BlueTEC system, and deposit Li on the surface of the high-entropy oxide layer by discharging. The current density is 0.2 mA / cm 2 , discharge for 10 h, take out the copper foil after deposition, and thus obtain the required lithium metal negative electrode with high-entropy interface modification..

[0038] Example 3

[0039] Step 1: Prepare a high-entropy target, which is a high-entropy alloy composed of four elements, Ni, Mn, Mo, and Au, in a molar ratio of 2:3:4:5.

[0040] Step 2: Cut the Cu foil into pieces of 5 cm × 5 cm, and ultrasonically clean them with acetone, ethanol, and deionized water respectively for 10 min in each process to remove the oil stains and impurity particles on the surface of the Cu foil; place the cleaned substrate in a blast drying oven at 80 °C to dry the residual water on its surface.

[0041] Step 3: Fix the dried substrate to the substrate base, install the high-entropy alloy target and the SiO2 target in the target positions, adjust the direction of the sputtering target positions so that the targets face the substrate directly, seal the sputtering chamber, the distance range from the target to the Cu substrate is 8 cm, and the background vacuum is 2×10 -4 Pa; Turn on the revolution switch, and the substrate rotation speed is 8 r min -1 , after glow discharge, close the baffle, and pre-sputter for 30 min to remove impurities on the surface of the target;

[0042] Step 4: Formally sputter to prepare (NiMnMoAu) x Si y O high-entropy oxide layer, the sputtering temperature is 25 °C, the sputtering power of the high-entropy alloy target is 20 W, the sputtering power of the SiO2 target is 150 W, the process vacuum is 0.5 Pa, the argon gas flow rate is 100 sccm, and the substrate rotation speed is 8 r min -1 , and the sputtering time is 10 min; After sputtering, take out the Cu foil;

[0043] Step 5: Use the copper foil with the high-entropy oxide layer obtained in Step 4 as the positive electrode, use a lithium sheet with a diameter of 16 mm and a thickness of 1.2 mm as the negative electrode, use a BlueTEC system, and deposit Li on the surface of the high-entropy oxide layer by discharging, and the current density is 0.2 mA / cm 2 , discharge for 10 h, take out the copper foil after deposition, and the desired lithium metal negative electrode with high-entropy interface modification is obtained.

[0044] Example 4

[0045] Step 1: Prepare a high-entropy target, and the high-entropy target is a high-entropy alloy composed of four elements of Cu, Co, Mn, and Au in a molar ratio of 4:4:5:3;

[0046] Step 2: Cut the Cu foil into a size of 5 cm × 5 cm, and perform ultrasonic cleaning with acetone, ethanol, and deionized water respectively. Each process is ultrasonic for 10 min to remove oil stains and impurity particles on the surface of the Cu foil cut; Place the cleaned substrate in a blast drying oven at 80 °C to dry the residual water on its surface;

[0047] Step 3: Fix the dried substrate to the substrate base, install the high-entropy alloy target and the SiO2 target in the target positions, adjust the direction of the sputtering target positions so that the targets face the substrate directly, seal the sputtering chamber, the distance range from the target to the Cu substrate is 8 cm, and the background vacuum is 2×10 -4 Pa; Turn on the revolution switch, and the substrate rotation speed is 8 r min -1 , after glow discharge, close the baffle, and pre-sputter for 30 min to remove impurities on the surface of the target;

[0048] Step 4: Formal sputtering preparation (CuCoMnAu) x Si y O high-entropy oxide layer, sputtering temperature is 25 °C, sputtering power of the high-entropy alloy target is 20 W, sputtering power of the SiO2 target is 150 W, process vacuum is 0.5 Pa, the argon flow rate is 100 sccm, and the substrate rotation speed is 8 r min -1 , sputtering time is 20 min; after sputtering, take out the Cu foil;

[0049] Step 5: Use the copper foil with the high-entropy oxide layer obtained in Step 4 as the positive electrode, use a lithium sheet with a diameter of 16 mm and a thickness of 1.2 mm as the negative electrode, use a blue electrochemical system, and deposit Li on the surface of the high-entropy oxide layer by discharging, with a current density of 0.2 mA / cm 2 , discharge for 10 h, take out the copper foil after deposition, and the desired lithium metal negative electrode with high-entropy interface modification is obtained.

[0050] As described above, it is only the specific implementation manner of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the features disclosed, or all the steps in any method or process, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A lithium metal anode modified with a high-entropy interface, characterized in that The lithium metal anode includes a copper foil, a high-entropy oxide layer attached to the surface of the copper foil, and lithium metal attached to the high-entropy oxide layer; the structural formula of the high-entropy oxide layer is (ABCD) x Si y O, where the four elements A, B, C, and D are different. Among them, A is any one of Ag, Cu, Ni, and Al; B is any one of Cr, Mn, Fe, and Co; C is any one of V, Mg, Mn, and Mo; D is any one of Zn, Au, Sn, and In.

2. The high-entropy interface-modified lithium metal anode according to claim 1, wherein, The thickness of the copper foil is 10 - 40 μm, and the thickness of the high-entropy oxide layer is 30 - 80 nm.

3. A preparation method of a lithium metal anode modified by a high-entropy interface, characterized in that, It includes the following steps: Step 1: Prepare a high-entropy target, which is a high-entropy alloy composed of four different elements A, B, C, and D in a molar ratio of a:b:c:d; Step 2: Clean the copper foil and dry it; Step 3: Using dual-source magnetron sputtering, with the copper foil cleaned in Step 2 as the sputtering substrate, and the high-entropy target and SiO2 target obtained in Step 1 as the sputtering targets, magnetron co-sputtering is carried out to prepare (ABCD) on the surface of the copper foil x Si y O high-entropy oxide layer; Step 4. Use the copper foil with a high-entropy oxide layer obtained in Step 3 as the positive electrode, a lithium sheet as the negative electrode, and use a blue electrochemical workstation. Deposit Li on the surface of the high-entropy oxide layer by discharging. After the deposition is completed, take out the copper foil to obtain the required lithium metal negative electrode with high-entropy interface modification.

4. The preparation method according to claim 3, characterized in that, In the high-entropy target of Step 1, the values of the molar ratios of the four elements are 0 < a ≤ 9, 0 < b ≤ 9, 0 < c ≤ 9, and 0 < d ≤ 9.

5. The preparation method according to claim 4, characterized in that, a:b:c:d is 1:1:1:

1.

6. The preparation method according to claim 3, characterized in that, In Step 3, the process parameters of magnetron co-sputtering are as follows: the sputtering temperature range is 20°C to 100°C, the sputtering power range is 5 W to 150 W, the background vacuum range is 4×10 -4 Pa to 2×10 -4 Pa, the process vacuum range is 0.5 Pa to 1.5 Pa, the distance range from the target to the substrate material is 6 cm to 10 cm; the argon gas flow rate range is 50 sccm to 150 sccm; the substrate rotation speed range is 5 r·min-1 to 10 r·min-1.

7. The preparation method according to claim 3, characterized in that, In Step 4, the process parameters of electroplating are: the current density and the electrodeposition time are determined according to the ratio of the capacity of the positive electrode to the capacity of the negative electrode.

8. Application of the lithium metal negative electrode with high-entropy interface modification obtained by the preparation method according to any one of claims 3 - 7 in a lithium metal battery.

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