A high entropy oxide thin film negative electrode material and its preparation method and application

Abstract

The present invention discloses a high entropy oxide thin film negative electrode material and its preparation method and application. A high entropy oxide thin film is deposited on a copper foil substrate in one step using a magnetic filtered cathode vacuum arc method. The method specifically comprises the following steps: the substrate is placed in an ethanol solution for cleaning; the vacuum chamber is then placed in a vacuum chamber for evacuation; the substrate is sputtered and cleaned using argon gas under a negative bias of 300 to 600 V; a high entropy oxide thin film is deposited using a magnetic filtered cathode vacuum arc, and the thin film is deposited under arc current of 50 to 200 A, a positive bias of 20 to 40 V, a negative bias of 50 to 300 V, and an oxygen flow rate of 5 to 10 sccm. The deposition time is 0.5 to 2 hours. The present invention realizes the fine film formation of multiple metal oxides in one step at room temperature through the interaction between energetic ions and the surface / subsurface of a metal target. Compared with the method based on chemical synthesis, the ion technique can achieve wide-range regulation of oxide types, structures, and properties, and has better industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane materials, and more particularly to a high-entropy oxide thin film negative electrode material and a preparation method and application thereof. Background Art

[0002] High-entropy materials (HEMs) are a class of materials recently proposed as single-phase materials containing five or more elements dissolved in equimolar or near-equimolar ratios. Their unique configuration and tunable functionality have attracted widespread attention. The design strategy for HEMs originated from high-entropy alloys (HEA). In 2004, Yeh et al. (Advanced Engineering Materials, 2004, 6:299-303) first proposed increasing the mixing entropy of an alloy by adding more elements. High mixing entropy can hinder the formation of intermetallic compounds, thereby promoting the formation of simple solid solution phases, thus introducing the concept of HEA. As research deepened, researchers discovered that HEAs exhibit unique effects in thermodynamics, kinetics, microstructure, and performance, including the high-entropy effect, delayed diffusion effect, lattice distortion effect, and "cocktail" effect. Compared with traditional alloys, HEAs possess superior mechanical properties, thermodynamic stability, electromagnetic properties, and catalytic activity, and are expected to be used in specialized applications such as high-pressure, high-temperature, and wear-resistant applications, as well as in energy and environmental fields. Meanwhile, the successful implementation of high-entropy alloys has inspired researchers to actively explore other types of high-entropy materials. Currently, high-entropy material design strategies have been extended to a variety of functional ceramic materials, including oxides, sulfides, carbides, nitrides, borides, and silicates. In 2015, Rost et al. (Nature Communications, 2015, 6:8485) constructed cation-disordered oxides by randomly and uniformly filling the same lattice site with different cations. They demonstrated that increasing the configurational entropy can promote reversible transformations between multiphase mixtures and single-phase solid solutions of five binary oxides. This research achievement marked the birth of high-entropy oxides. In recent years, high-entropy oxide materials have attracted widespread attention in the field of energy storage and conversion, especially in electrochemical energy storage materials. The introduction of high-entropy design concepts has greatly expanded the design space for electrochemical energy storage materials, creating new opportunities to overcome the current performance bottlenecks of electrode materials.

[0003] At present, conventional methods for preparing high-entropy oxide negative electrode materials for lithium-ion batteries include high-temperature solid-phase method, high-energy ball milling method, carbon thermal reduction method, chemical precipitation method, etc. These methods usually require high-temperature sintering of thousands of degrees during the reaction process, and the preparation time is as long as more than ten hours. In addition, the oxide particles are prone to agglomeration, resulting in degradation of electrochemical performance. For example, patent CN114606457A discloses a high-entropy alloy oxide and its preparation method. The alloying elements are Cu, Mn, Co, Fe and Ni. The method first uses mechanical ball milling to mix pure metal powders, then plasma sprays CuMnCoFeNi high-entropy alloy coatings, and finally uses high-temperature high-oxygen pressure thermal growth to form a high-entropy oxide coating. Xiao et al. (Nano Energy, 2022, 95: 106962) calcined FeCoNiCrMn high-entropy alloy powder in an oxygen environment at 1000℃ for 12 hours to synthesize (FeCoNiCrMn)3O4 high-entropy oxide negative electrode material with a 2.0A g -1 The specific capacity at the current density is 596.5 mAh g -1 After 1200 cycles, the capacity retention rate is 86.2%. Summary of the Invention

[0004] In view of this, the present invention addresses the technical problems of high reaction temperature, long processing time, and multiple preparation steps in the above-mentioned conventional methods, and proposes an efficient preparation method for high-entropy oxide negative electrode materials based on ion beam technology. This method achieves fine film formation of various metal oxides in one step at room temperature through the interaction between energy-carrying ions and the surface / subsurface of the metal target material. The preparation efficiency of high-entropy oxides is significantly higher than that of conventional methods such as high-temperature solid-phase methods. In addition, ion beam technology has unique technical advantages in the preparation of high-entropy oxide films. The type, energy, density, incident angle and working pressure of the ion beam can be independently controlled within a wide range. Compared with methods based on chemical synthesis, ion technology can achieve wide-range regulation of oxide types, structures and properties, and has better prospects for industrial application.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a high entropy oxide thin film negative electrode material, which uses a magnetic filtered cathode vacuum arc method to deposit a high entropy oxide thin film on a copper foil substrate in one step, specifically comprising the following steps:

[0007] (1) Wash the substrate in an ethanol solution;

[0008] (2) After cleaning, the substrate is placed in a vacuum chamber and evacuated;

[0009] (3) sputter cleaning the substrate using argon gas under a negative bias voltage of -300 to -600 V;

[0010] (4) A magnetic filtered cathode vacuum arc was used to deposit a high entropy oxide film. The film deposition was performed under the conditions of an arc current of 50 to 200 A, a positive bias of 20 to 40 V, a negative bias of -50 to -300 V, and an oxygen flow rate of 5 to 10 sccm. The deposition time was 0.5 to 2 h.

[0011] The beneficial effects of adopting the above technical solution are:

[0012] Preferably, the volume concentration of the ethanol solution in step (1) is 90-95%, and the cleaning time is 3-10 minutes.

[0013] Preferably, after step (2) vacuuming, the working pressure is controlled to be less than or equal to 1×10 -2 Pa.

[0014] Preferably, four metal targets, namely CoNi target, Cu target, Mg target and Zn target, with Co and Ni atomic fractions of 50% each, are used as cathode arc sources to deposit rock salt structure (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 )O film, the purity of the CoNi, Cu, Mg and Zn are all 99.99%.

[0015] Preferably, four metal targets, namely NiCr target, Fe target, Co target and Mn target, with Ni and Cr atomic fractions of 50% each, are used as cathode arc sources to deposit spinel structure (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 film, the purity of NiCr, Fe, Co and Mn are all 99.99%.

[0016] Preferably, the ion beam types of the magnetic filtered cathode vacuum arc cover all metal elements except the first and second main groups, the energy is continuously adjustable from 10eV to 1MeV, and the density is continuously adjustable from 10 8 to 10 13 cm -3 Continuously adjustable, the incident angle is continuously adjustable from 0 degrees to 180 degrees, and the working pressure is continuously adjustable from 0.1Pa to 10Pa.

[0017] Preferably, the thickness of the film is 10 to 1000 nm.

[0018] Beneficial effects of the present invention:

[0019] (1) High preparation efficiency, high-quality film formation can be achieved at room temperature, making it more suitable for industrial applications;

[0020] (2) The process is highly controllable, and the types, structures, and properties of oxides can be regulated over a wide range.

[0021] (3) The battery assembled with lithium sheet as the positive electrode and the high entropy oxide film of the present invention as the negative electrode material has high specific capacity and strong cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the preparation process of the high entropy oxide thin film negative electrode material of the present invention.

[0023] Figure 2 (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide thin film negative electrode cycle performance curve. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] Example 1:

[0026] (1) Wash the copper foil substrate in 95% ethanol solution for 5 minutes, dry it, and then place it in a vacuum chamber to evacuate to 1×10 -2 Pa. Four targets, NiCr (Ni and Cr atomic fractions of 50%, purity 99.99%), Fe (purity 99.99%), Co (purity 99.99%), and Mn (purity 99.99%), were used as cathode arc sources. Copper foil was used as the substrate. The substrate was sputter-cleaned at a negative bias of -400 V for 1 min with an argon flow rate of 80 sccm.

[0027] (2) Using magnetic filtered cathode vacuum arc technology and oxygen as background gas, the surface of the cleaned copper foil substrate was prepared (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide film, the deposition disk is 10 cm away from the plasma outlet, the arc current is 100 A, the positive bias voltage is 30 V, the negative bias voltage is -200 V, the oxygen flow rate is 8 sccm, the deposition time is 1 h, the incident ion energy is 80 KeV, the density is 10 11 cm -3, the incident angle is 90 degrees, the working pressure is 5Pa, and the relative content of elements in the film is measured by EDS spectrometer. The atomic percentages of the five metal elements Fe, Co, Ni, Cr, and Mn are 8.57%, 8.49%, 8.65%, 8.53%, and 8.62%, respectively, and the atomic percentage of the O element is 57.14%;

[0028] (3) The obtained (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide film is used as the negative electrode of lithium-ion battery, and the battery is directly assembled with copper foil substrate without adhesive and conductive agent. -1 The specific capacity after 100 cycles at the current density is 1006.8 mA h g -1 , the capacity retention rate is 88.2%.

[0029] Attachment Figure 2 The parameters described in Example 1 were used to prepare (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide thin film negative electrode cycle performance curve.

[0030] Comparative Example 1:

[0031] (1) FeCoNiCrMn high entropy alloy powder (average particle size 50 μm) was calcined at 1000°C in an oxygen atmosphere for 12 h to prepare (FeCoNiCrMn)3O4 high entropy oxide;

[0032] (2) annealing the prepared (FeCoNiCrMn)3O4 high entropy oxide at 500°C and naturally cooling it to room temperature;

[0033] (3) Polyvinylidene fluoride (binder), acetylene black (conductive agent) and cooled (FeCoNiCrMn)3O4 high entropy oxide were uniformly mixed (weight ratio 1:1:8), coated on the copper foil current collector, dried in a vacuum drying oven at 120 °C for 8 h, and then assembled into a battery. -1 The specific capacity after 100 cycles at the current density is 519.6 mA h g -1 , the capacity retention rate is 87.1%.

[0034] Example 2:

[0035] (1) The copper foil substrate was washed in 92% ethanol solution for 3 minutes. After drying, the substrate was placed in a vacuum chamber and evacuated to 5×10 -3Pa. Four targets, CoNi (Co and Ni atomic fractions of 50%, purity 99.99%), Cu (purity 99.99%), Mg (purity 99.99%), and Zn (purity 99.99%), were used as cathode arc sources. Copper foil was used as the substrate. The substrate was sputter-cleaned at a negative bias of -300 V for 1 min with an argon flow rate of 80 sccm.

[0036] (2) Using magnetic filtered cathode vacuum arc technology, with oxygen as background gas, the surface of the cleaned copper foil substrate was prepared (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 )O high entropy oxide film, the deposition disk is 10 cm away from the plasma outlet, the arc current is 50 A, the positive bias voltage is 20 V, the negative bias voltage is -100 V, the oxygen flow rate is 5 sccm, the deposition time is 0.5 h, the incident ion energy is 60 KeV, and the density is 10 10 cm -3 , the incident angle is 90 degrees, the working pressure is 5Pa, and the relative content of elements in the film is measured by EDS spectrometer. The atomic percentages of the five metal elements Co, Cu, Mg, Ni, and Zn are 10.01%, 10.07%, 9.98%, 10.05%, and 9.97%, respectively, and the atomic percentage of the O element is 49.92%;

[0037] (3) The obtained (Co 0.2 Cu 0.2 Mg 0.2 Ni 0.2 Zn 0.2 )O high entropy oxide film is used as the negative electrode of lithium-ion battery, and the battery is directly assembled with copper foil substrate without adhesive and conductive agent. -1 The specific capacity after 100 cycles at the current density is 850.6 mA h g -1 , the capacity retention rate is 82.5%.

[0038] Comparative Example 2:

[0039] (1) CoCuMgNiZn high entropy alloy powder (average particle size 50 μm) was calcined at 1000°C in an oxygen atmosphere for 12 h to prepare (CoCuMgNiZn)O high entropy oxide.

[0040] (2) annealing the prepared (CoCuMgNiZn)O high entropy oxide at 500°C and naturally cooling it to room temperature;

[0041] (3) Polyvinylidene fluoride (binder), acetylene black (conductive agent) and cooled (CoCuMgNiZn)O high entropy oxide were uniformly mixed (weight ratio 1:1:8), coated on the copper foil current collector, dried in a vacuum drying oven at 120 °C for 8 h, and then assembled into a battery. -1 The specific capacity after 100 cycles at the current density is 505.2 mA h g -1 , the capacity retention rate is 75.1%.

[0042] Example 3:

[0043] (1) Wash the copper foil substrate in 90% ethanol solution for 10 minutes, dry it, and then place it in a vacuum chamber to evacuate to 5×10 -3 Pa. Four targets, NiCr (Ni and Cr atomic fractions of 50%, purity 99.99%), Fe (purity 99.99%), Co (purity 99.99%), and Mn (purity 99.99%), were used as cathode arc sources. Copper foil was used as the substrate. The substrate was sputter-cleaned at a negative bias of -500 V for 1 min with an argon flow rate of 80 sccm.

[0044] (2) Using magnetic filtered cathode vacuum arc technology and oxygen as background gas, the surface of the cleaned copper foil substrate was prepared (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide film, the deposition disk is 10 cm away from the plasma outlet, the arc current is 150 A, the positive bias voltage is 40 V, the negative bias voltage is -300 V, the oxygen flow rate is 10 sccm, the deposition time is 1.5 h, the incident ion energy is 90 KeV, the density is 10 12 cm -3 , the incident angle is 45 degrees, the working pressure is 8 Pa, and the relative content of elements in the film is measured by EDS spectrometer. The atomic percentages of the five metal elements Fe, Co, Ni, Cr, and Mn are 8.52%, 8.61%, 8.55%, 8.49%, and 8.58%, respectively, and the atomic percentage of the O element is 57.25%;

[0045] (3) The obtained (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 high entropy oxide film is used as the negative electrode of lithium-ion battery, and the battery is directly assembled with copper foil substrate without adhesive and conductive agent. -1 The specific capacity after 100 cycles at the current density is 927.2 mA h g -1, the capacity retention rate is 85.6%.

[0046] Comparative Example 3:

[0047] (1) FeCoNiCrMn high entropy alloy powder (average particle size 50 μm) was calcined at 800°C in an oxygen atmosphere for 12 h to prepare (FeCoNiCrMn)3O4 high entropy oxide;

[0048] (2) annealing the prepared (FeCoNiCrMn)3O4 high entropy oxide at 400°C and naturally cooling it to room temperature;

[0049] (3) Polyvinylidene fluoride (binder), acetylene black (conductive agent) and cooled (FeCoNiCrMn)3O4 high entropy oxide were uniformly mixed (weight ratio 1:1:8), coated on the copper foil current collector, dried in a vacuum drying oven at 120 °C for 8 h, and then assembled into a battery. -1 The specific capacity after 100 cycles at the current density is 480.3 mA h g -1 , the capacity retention rate is 82.2%.

[0050] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0051] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a high entropy oxide thin film negative electrode material, characterized in that: A high entropy oxide thin film is deposited on a copper foil substrate in one step using a magnetic filtered cathode vacuum arc method, which specifically includes the following steps: (1) Clean the substrate in an ethanol solution; (2) After cleaning, place the substrate in a vacuum chamber and evacuate the chamber; after evacuation, control the working pressure to be less than or equal to 1×10 - 2 Pa; (3) sputter cleaning the substrate using argon gas under a negative bias voltage of -300 to -600 V; (4) High entropy oxide thin films were deposited using a magnetic filtered cathode vacuum arc. Four metal targets, including NiCr target, Fe target, Co target, and Mn target, with Ni and Cr atomic fractions of 50%, were used as cathode arc sources to deposit spinel structure (Fe 0.2 Co 0.2 Ni 0.2 Cr 0.2 Mn 0.2 )3O4 thin film, the purity of NiCr, Fe, Co, and Mn is 99.99%; the thin film is deposited under the conditions of arc current of 50 to 200A, positive bias of 20 to 40V, negative bias of -50 to -300V, oxygen flow rate of 5 to 10sccm, and deposition time of 0.5 to 2h; The ion beam types of the magnetic filtered cathode vacuum arc cover all metal elements except the first and second main groups, with energy continuously adjustable from 10eV to 1MeV and density from 10 8 to 10 13 cm -3 Continuously adjustable, the incident angle is continuously adjustable from 0 degrees to 180 degrees, and the working pressure is continuously adjustable from 0.1Pa to 10Pa.

2. The method for preparing a high entropy oxide thin film negative electrode material according to claim 1, characterized in that: The volume concentration of the ethanol solution in step (1) is 90-95%, and the cleaning time is 3-10 minutes.

3. The method for preparing a high entropy oxide thin film negative electrode material according to claim 1, characterized in that: The thickness of the deposited film is 10 to 1000 nm.

4. A high entropy oxide thin film negative electrode material prepared according to the preparation method according to any one of claims 1 to 3.

5. Use of the high entropy oxide thin film negative electrode material according to claim 4 in a lithium ion battery.

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