Super capacitor film electrode material and preparation method thereof

Abstract

The invention provides a supercapacitor film electrode material and a preparation method thereof, and belongs to the technical field of supercapacitor electrode materials, and the supercapacitor film electrode material comprises a substrate and a multi-principal-element nitride film attached to the substrate; the multi-principal-element nitride thin film is composed of (CrMoNbVX) N, wherein X is one of other transition metal elements except Cr, Mo, Nb and V; the organization structure of the multi-principal-element nitride thin film is a face-centered cubic structure, and the surface roughness is 9-20 nm. Through the characteristic of atomic-scale uniform distribution of multiple elements, a synergistically enhanced electron transport network is effectively constructed, the conductivity and electrochemical stability of the electrode are remarkably improved, the self-supporting thin film structure has the densification characteristic and the zero binder advantage, the charge transport path is shortened to the nanoscale, and the self-supporting thin film structure is suitable for large-scale application. And the curved surface packaging requirement of the miniaturized wearable equipment can be perfectly met.

Description

Technical Field

[0001] The present invention relates to the technical field of supercapacitor electrode materials, and particularly relates to a supercapacitor thin film electrode material and a preparation method thereof. Background Art

[0002] With the rapid development of social economy, rapid growth of population, rapid development of hybrid vehicles and increasing demand for portable electronic devices, global energy is being consumed at an accelerating rate. However, the continuous reduction of non-renewable energy makes people pay more attention to the development and utilization of renewable energy. Therefore, energy storage technology has become an indispensable key link in the development of the new energy industry. As a new type of energy storage device, the supercapacitor fills the energy storage area between traditional capacitors and lithium-ion batteries. It has advantages such as high power density and good cycle performance, but its power density is relatively low, which restricts the application range of supercapacitors. The structure of a supercapacitor mainly consists of four parts: current collector, electrode, electrolyte and separator. Among them, the electrode material plays a decisive role in the energy storage performance of the supercapacitor. Therefore, how to design and prepare high-performance electrode materials is the key to developing and researching supercapacitors with both high power density and high energy density.

[0003] Due to their unique physical and chemical properties, transition metal nitride thin film electrode materials have received extensive attention in the field of supercapacitors in recent years. However, for binary transition metal nitride thin film materials, at high potential windows (especially in acidic or neutral electrolytes), the nitride surface is prone to oxidation corrosion, resulting in a decrease in cycle stability. For example, the literature "J. Deng, Y. Tang, et al., Nano Energy. 80, 105536(2021)" points out that the capacitance retention rate of TiN thin film is only 78% after 10,000 cycles, mainly due to the structural degradation caused by the loss of active nitrogen atoms. Secondly, the high-temperature treatment (500 °C) of the substrate during the thin film preparation process limits its compatibility in flexible devices. In addition, the specific surface area of binary transition metal nitrides is generally low, with fewer active sites and lower specific capacitance.

[0004] As a new type of multi-component and multi-functional material, multi-principal element nitrides have shown unique advantages in the field of supercapacitor electrodes in recent years. Their core feature is that a single-phase solid solution structure is formed by four or more principal element atoms in a near equimolar ratio. Through the synergistic effects of the multi-principal element effect, lattice distortion effect, and slow diffusion effect, the electrochemical stability, mechanical strength, and functional tunability of the material are significantly improved. Traditional methods for preparing multi-principal element nitrides usually involve nitriding metal oxides. However, such methods have a cumbersome process and high reaction temperatures (600 - 800 °C), and usually involve the use of toxic nitrogen sources (such as NH3). Secondly, the nitrides prepared by the nitriding method usually exist in the form of powders, which requires the addition of an additional binder to prepare the electrodes, so the conductivity and mechanical strength between the active material and the current collector are often poor. Patent CN117577457A discloses an electrode material based on Al 75 Fe5Cu5Ni5Cr5Mn5 high-entropy alloy, which constructs a porous structure through arc melting and dealloying processes, and exhibits a specific capacitance of 312 F / g in acidic or alkaline electrolytes. However, a binder needs to be added when preparing the electrodes, the structure is prone to cracking, the transmission path is long and not flexible enough. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present application provides a supercapacitor thin-film electrode material and its preparation method, aiming to solve the technical problems of insufficient power density and energy density of the electrode materials of existing supercapacitors.

[0006] In a first aspect, an embodiment of the present application provides a supercapacitor thin-film electrode material, including a substrate and a multi-principal element nitride thin film attached to the substrate; the multi-principal element nitride thin film is composed of (CrMoNbVX)N, where X is one of the other transition metal elements except Cr, Mo, Nb, and V; the organizational structure of the multi-principal element nitride thin film is a face-centered cubic (FCC) structure, the surface roughness is 9 - 20 nm, and the thickness is 500 - 1500 nm.

[0007] In the technical solution of the embodiment of the present application, the Cr element has corrosion resistance that can extend the service life of equipment in the energy storage field; the Mo-based compound can be used as an electrode for supercapacitors to achieve high power density and fast charge and discharge; the Nb-based compound, as the negative electrode of a lithium-ion battery, has high rate performance and short charge and discharge time; the V-based compound has high stability in acidic / alkaline electrolytes and is suitable for various battery systems; after CrMoNbV is nitrided, it has a more stable structure, and the metal nitride has excellent electrical conductivity, corrosion resistance, and electrochemical stability. By adding additional transition metal elements to CrMoNbV and obtaining a multi-principal element nitride through nitridation, it has a high-entropy effect. Driven by the high-entropy effect, the structure of the material is simple and stable. When used as an electrode, it can prevent volume shrinkage during charge and discharge and improve electrochemical stability; secondly, it has a "lattice distortion effect", and lattice distortion leads to the formation of a large number of vacancies, which can provide more redox sites; kinetically, it has a sluggish diffusion effect, which prevents the aggregation of nanoparticles and improves antioxidant performance; secondly, due to the interaction between different elements, a synergistic effect is generated when multiple cations coexist, enabling the material to exhibit excellent electrochemical performance in the energy storage field.

[0008] The face-centered cubic (FCC) structure has a large pore space and a symmetric atomic arrangement, which can optimize the ion diffusion path and the electron transport network, achieving high power density and fast charge and discharge; it has excellent structural stability, with a low volume expansion rate during the charge and discharge process, extending the cycle life of the device and reducing maintenance costs.

[0009] In some embodiments, for the thin-film electrode material, at a current density of 10 mV / s, the areal specific capacitance is greater than or equal to 100 mF / cm 2 .

[0010] In some embodiments, the substrate is stainless steel or single-crystalline silicon.

[0011] In the technical solution of the embodiment of the present application, single-crystalline silicon: Single-crystalline silicon has a long-range ordered structure with a single crystal phase, providing an atomically flat interface for the epitaxially grown thin-film material. Its lattice matching characteristics can reduce the density of film defects, improve the charge transport efficiency of the electrode material, and thus optimize the rate performance of the supercapacitor; secondly, the purity of single-crystalline silicon reaches more than 99.999%, effectively avoiding interfacial side reactions caused by impurities, and can relieve the volume expansion effect on the nanostructure supported by the silicon substrate, extending the cycle life.

[0012] Stainless steel substrate: As a metal conductor, stainless steel can omit the additional conductive layer deposition step in the traditional process, can directly serve as the substrate of a bipolar electrode, and has low raw material costs, showing significant economy in the large-scale production of thin-film electrode materials. Secondly, the high hardness and electrolyte corrosion resistance of stainless steel make it suitable as a current collector in flexible energy storage devices.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a supercapacitor thin film electrode material, including the following steps: (1) Pretreat the substrate; (2) Deposit a multi-principal element nitride thin film on the pretreated substrate by magnetron sputtering; The magnetron sputtering uses a multi-principal element alloy as a target, and the multi-principal element alloy includes Cr, Mo, Nb, V, and X, where X is one of the other transition metal elements except Cr, Mo, Nb, and V, and the molar ratio of Cr, Mo, Nb, V, and X is 1:1:1:1:1.

[0014] In the technical solution of the embodiment of the present application, a multi-principal element alloy is prepared by powder metallurgy, and a high-entropy nitride thin film is deposited by a single-target DC reactive magnetron sputtering system. Only the sputtering power of the single target needs to be adjusted to prepare high-entropy nitride thin films with different crystal morphologies. During the deposition process, there is no need to replace and adjust the raw materials in the system. The process is simple and the operation is convenient.

[0015] In some embodiments, the process conditions of the magnetron sputtering are: argon is used as the working gas, nitrogen is used as the reaction gas, the air pressure in the vacuum chamber is less than or equal to 1×10 -3 Pa, the DC sputtering power is 100-200 W, the substrate bias voltage is 0- -100 V, the deposition pressure is 2.5-4 Pa, the deposition temperature is 100-300 °C, and the deposition time is 30-90 min.

[0016] In the technical solution of the embodiment of the present application, using a multi-principal element alloy as a target and nitrogen as the reaction gas, a multi-principal element nitride thin film can be formed on the surface of the substrate by magnetron sputtering.

[0017] Control the air pressure in the vacuum chamber to be less than or equal to 1×10 -3 Pa. If the vacuum degree is higher than this value, it may cause the oxidation of the multi-principal element nitride thin film to form metal oxides. The prepared multi-principal element nitride thin film has a non-single phase structure, resulting in a decrease in conductivity, an increase in interface internal resistance, further hindering electron transport, reducing the electro-chemical reaction efficiency, and thus leading to a decrease in the electrode specific capacitance value.

[0018] The deposition temperature is 100~300 °C, and the substrate bias voltage is 0~-100 V. The multi-principal element nitride thin films prepared within this range have a high porosity, which can provide more active sites to contact with the electrolyte ions in the supercapacitor, thereby providing excellent capacitance. If the substrate temperature is too high, the film densifies at high temperature, and the nano-scale pores decrease, resulting in a decrease in the effective reaction area and a reduction in the specific capacitance value. If the temperature is too low, due to limited atomic migration, the electrode film often presents an amorphous state, and multi-principal element nitrides may not be formed at too low temperatures. When a relatively high bias voltage is applied to the substrate, it may introduce high-density defects (such as dislocations and grain boundaries), which hinder ion diffusion (such as Li + , Na + ), increasing the interfacial impedance.

[0019] The deposition pressure is 2.5~4 Pa. When the deposition pressure is lower than 2.5 Pa, the mean free path of the sputtering particles is long and the kinetic energy is high. The formed film is denser, the specific surface area is small, and the ion diffusion path is long, resulting in a decrease in the specific capacitance. When the deposition pressure is too high, the gas molecule density in the deposition chamber increases, resulting in an increase in the collision frequency between the sputtering particles and the gas atoms. This increased particle scattering leads to kinetic energy loss. At higher pressures, the energy of the sputtering particles when they reach the substrate decreases, which limits the mobility of the sputtering particles and reduces the atomic diffusion efficiency. This results in the film showing a higher porosity, smaller grain size, and lower crystallinity. Although this porosity may be beneficial in some cases, such as providing more active sites for electrochemical reactions, excessive porosity will damage the mechanical stability and conductivity of the film. The increased surface roughness and the development of structural defects may also lead to a decrease in long-term cycle stability, especially under high-current charge-discharge conditions.

[0020] The DC sputtering power is 100~200 W. At too low sputtering power, the increased atomic mobility helps to reduce the formation of defects such as voids and dislocations, but these defects may have a negative impact on the conductivity and cycle stability of the film. Too high a magnetron sputtering power usually increases the deposition rate and film thickness, enhancing the conductive path and mechanical strength. However, too high a sputtering power may cause crucial adverse effects, such as increasing internal stress and excessive grain growth. These factors may damage the long-term stability and cycle performance of the electrode material. This is because high power accelerates the film growth rate, making the deposition process more difficult to control, resulting in larger grain size, reduced surface area, and increased internal stress. These problems, especially the internal stress generated by rapid deposition, can form mechanical failure points, damage the integrity of the film, and cause delamination or cracking during repeated charge-discharge cycles.

[0021] The deposition time is 30 to 90 minutes. Within this range, the film thickness is relatively thin and the specific capacitance is relatively high. If the deposition time is too long, the formed film will be thicker, the ion diffusion path will be long, resulting in an increase in impedance, a decrease in rate performance, and a reduction in specific capacitance.

[0022] In some embodiments, the flow rate ratio of argon to nitrogen is 1:1, and the flow rate of the argon is 10 to 150 sccm.

[0023] In some embodiments, the substrate pretreatment step in step (1) includes: The substrate is ultrasonically cleaned successively with acetone, absolute ethanol, and deionized water to obtain a clean substrate; The clean substrate is subjected to glow cleaning. The process conditions for glow cleaning are: using argon as the working gas, the argon flow rate is 150 sccm, the air pressure in the vacuum chamber is less than 1×10 -3 Pa, the cleaning time is 10 to 30 minutes, and the substrate bias voltage is 0 to -100 V.

[0024] In the technical solution of the embodiment of the present application, the substrate is first ultrasonically cleaned with acetone. The high solubility characteristic of acetone can remove surface organic pollutants and particulate matter; then ethanol is used to remove acetone residues and dissolve polar pollutants, and then deionized water is used to eliminate ethanol residues, achieving complete cleaning of the substrate surface.

[0025] After solvent cleaning is completed, glow cleaning is then carried out. During the glow cleaning process, Ar + bombards the surface of the substrate to remove the oxide layer on the surface of the substrate.

[0026] In some embodiments, before depositing the multi-principal element nitride film on the substrate in step (2), target pre-sputtering is first performed to remove impurities on the surface of the target.

[0027] In some embodiments, the process conditions for target pre-sputtering are: using 50 sccm of argon as the working gas, 50 sccm of nitrogen as the reaction gas, the pre-sputtering power is 50 to 200 W, and the time is 10 to 20 minutes.

[0028] In the technical solution of the embodiment of the present application, target pre-sputtering is to remove impurities such as oxides on the surface of the target. The pre-sputtering time should not exceed 20 minutes. An excessively long time will cause waste of target resources.

[0029] In the technical solution of the embodiment of the present application, when performing target pre-sputtering, the substrate baffle is closed so that the target is sputtered onto the substrate baffle. After removing the impurities on the surface of the target, the substrate baffle is then opened so that the target is sputtered onto the substrate.

[0030] In some embodiments, the rotation speed of the substrate in step (2) is 10 - 20 r / min.

[0031] In the technical solution of the embodiment of the present application, the rotation speed of the substrate is 10 - 20 r / min. Too high or too low rotation speed will cause uneven film deposition, thereby affecting the film deposition rate and quality.

[0032] Different from the prior art solutions, the beneficial effects of the present application include: 1. The present invention innovatively develops a multi-principal-element CrMoNbV-based high-entropy nitride thin film electrode material. Through the characteristic of uniform atomic distribution of multiple elements, a synergistically enhanced electron transport network is effectively constructed, significantly improving the electrode conductivity and electrochemical stability, and breaking through the performance bottleneck of traditional supercapacitor electrode materials. Compared with powder electrodes, this self-supporting thin film structure has both densification characteristics and the advantage of zero binder, shortening the charge transport path to the nanoscale and perfectly adapting to the curved surface packaging requirements of miniaturized wearable devices.

[0033] The CrMoNbV-based high-entropy nitride thin film optimized with transition metal elements exhibits significantly enhanced charge storage capacity in acidic electrolytes. This performance leap stems from the synergistic contribution of pseudocapacitance enhancement and electric double layer capacitance induced by the multi-principal-element synergistic effect.

[0034] The face-centered cubic (FCC) structure has a large pore space and symmetric atomic arrangement, which can optimize the ion diffusion path and electron transport network, achieving high power density and fast charge and discharge; it has excellent structural stability, with a low volume expansion rate during charge and discharge, extending the device cycle life and reducing maintenance costs.

[0035] 2. The present invention abandons the dependence on conductive agents / binders in the traditional physical mixing method. This technology realizes the direct deposition of high-intrinsic-conductivity thin films through precise component regulation, with the material utilization rate increased to over 98%, avoiding the use of organic solvents, and reducing the energy consumption of single-electrode preparation by 40%, meeting the sustainable manufacturing requirements under the carbon neutrality goal.

[0036] 3. The present invention innovatively adopts the single-target DC reactive magnetron sputtering technology, and the controllable growth of multi-principal-element nitride thin films can be achieved only through dynamic regulation of the target power. This process does not require frequent target replacement or chamber configuration adjustment, and has a high deposition rate, laying a foundation for the large-scale application of multi-principal-element nitride thin films.

[0037] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] To more clearly illustrate the technical solutions of this application, the attached drawings used in this application will be briefly introduced below. Obviously, the attached drawings described below are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other attached drawings can also be obtained based on these attached drawings.

[0039] Figure 1 XRD pattern of the multi-principal element CrMoNbVTi nitride thin film electrode prepared in Example 1 of the present invention.

[0040] Figure 2 SEM surface morphology of the multi-principal element CrMoNbVTi nitride thin film electrode prepared in Example 1 of the present invention.

[0041] Figure 3 AFM surface morphology of the multi-principal element CrMoNbVTi nitride thin film electrode prepared in Example 1 of the present invention.

[0042] Figure 4 Cyclic voltammogram of the multi-principal element CrMoNbVTi nitride thin film electrode prepared in Example 1 of the present invention. Detailed implementation manners

[0043] The embodiments of the technical solutions of this application will be described in detail below with reference to the attached drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this application, so they are only examples and cannot be used to limit the protection scope of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above attached drawing descriptions are intended to cover non-exclusive inclusion.

[0045] Referring to "embodiments" in this context means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0046] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those without specific technologies or conditions noted in the embodiments, the technologies or conditions described in the literature in this field or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchases.

[0047] I. Preparation Method Example 1 A preparation method of a supercapacitor thin-film electrode material includes the following steps: (1) Immerse the substrate sequentially in three media: acetone, absolute ethanol, and deionized water for step-by-step ultrasonic treatment, and set the treatment duration to 15 minutes for each cleaning stage. After completing the liquid-phase cleaning, transfer the sample to a vacuum drying oven for solid-phase drying, control the temperature parameter at 60 °C and keep it for 10 minutes to obtain a clean substrate.

[0048] Place the clean substrate on the substrate stage of the magnetron sputtering system for glow cleaning. The process conditions for glow cleaning are as follows: use argon as the working gas, the argon flow rate is 150 sccm, the air pressure in the vacuum chamber is 1×10 -3 Pa, the cleaning time is 10 minutes, and the substrate bias voltage is -100 V.

[0049] (2) Load the multi-principal element CrMoNbVTi alloy target into the deposition chamber of the magnetron sputtering system, evacuate the vacuum in the vacuum chamber to the background vacuum degree of 1×10 -3 Pa, apply a deposition temperature of 100 °C and a bias voltage of -100 V to the substrate. When the deposition temperature is reached, introduce the working gas argon and the reactive gas nitrogen, and the gas flow ratio Ar:N2 = 1:1. The argon flow rate is 50 sccm, and use the pressure valve to adjust the deposition working air pressure to 2.5 Pa.

[0050] (3) Start the magnetron sputtering equipment, adjust the substrate rotation speed to 10 r / min, turn on the DC sputtering power supply, set the DC sputtering power to 200 W, close the substrate baffle, after pre-sputtering for 20 minutes, open the substrate baffle, set the deposition time to 30 minutes, and after the deposition is completed, wait for the chamber to cool to room temperature and then take out.

[0051] Example 2 A preparation method of a supercapacitor thin-film electrode material includes the following steps: (1) Immerse the substrate sequentially in three media: acetone, absolute ethanol, and deionized water for step-by-step ultrasonic treatment, and set the treatment duration to 15 minutes for each cleaning stage. After completing the liquid-phase cleaning, transfer the sample to a vacuum drying oven for solid-phase drying, control the temperature parameter at 60 °C and keep it for 10 minutes to obtain a clean substrate.

[0052] Place the clean substrate on the substrate stage of the magnetron sputtering system and perform glow cleaning. The process conditions for glow cleaning are as follows: Argon is used as the working gas, the argon flow rate is 150 sccm, the gas pressure in the vacuum chamber is 1×10 -3 Pa, the cleaning time is 20 min, and the substrate bias voltage is -100 V.

[0053] (2) Load the multi-principal element CrMoNbVZr alloy target into the deposition chamber of the magnetron sputtering system, evacuate the vacuum in the vacuum chamber to the background vacuum degree of 1×10 -3 Pa, apply a deposition temperature of 150 °C and a bias voltage of 0 V to the substrate. When the deposition temperature is reached, introduce the working gas argon and the reactive gas nitrogen, and the gas flow ratio Ar:N2 = 1:1. Use the pressure valve to adjust the deposition working gas pressure to 4 Pa.

[0054] (3) Start the magnetron sputtering equipment, adjust the substrate rotation speed to 10 r / min, turn on the DC sputtering power supply, set the DC sputtering power to 100 W, close the substrate baffle. After pre-sputtering for 20 min, open the substrate baffle and set the deposition time to 90 min. After the deposition is completed, wait for the chamber to cool to room temperature and then take out the sample.

[0055] Example 3 A preparation method of a supercapacitor thin film electrode material, comprising the following steps: (1) Immerse the substrate sequentially in three media of acetone, absolute ethanol and deionized water for step-by-step ultrasonic treatment, and set the treatment duration to 15 min for each cleaning stage. After the liquid-phase cleaning is completed, transfer the sample to a vacuum drying oven for solid-phase drying, control the temperature parameter to 60 °C and continue for 10 min to obtain a clean substrate.

[0056] Place the clean substrate on the substrate stage of the magnetron sputtering system and perform glow cleaning. The process conditions for glow cleaning are as follows: Argon is used as the working gas, the argon flow rate is 150 sccm, the gas pressure in the vacuum chamber is 1×10 -3 Pa, the cleaning time is 20 min, and the substrate bias voltage is -100 V.

[0057] (2) Load the multi-principal element CrMoNbVHf alloy target into the deposition chamber of the magnetron sputtering system, evacuate the vacuum in the vacuum chamber to the background vacuum degree of 1×10 -3 Pa, apply a deposition temperature of 300 °C and a bias voltage of -100 V to the substrate. When the deposition temperature is reached, introduce the working gas argon and the reactive gas nitrogen, and the gas flow ratio Ar:N2 = 1:1. Use the pressure valve to adjust the deposition working gas pressure to 3 Pa.

[0058] (3) Start the magnetron sputtering equipment, adjust the substrate rotation speed to 10 r / min, turn on the DC sputtering power supply, set the DC sputtering power to 150 W, close the substrate baffle, after pre-sputtering for 20 min, open the substrate baffle and set the deposition time to 60 min. After the deposition is completed, wait for the chamber to cool to room temperature and then take out the sample.

[0059] Comparative Example 1 Compared with Example 1, the difference in Comparative Example 1 is that in step (2), the vacuum degree in the vacuum chamber is 2*10 - 3 Pa.

[0060] Comparative Example 2 Compared with Example 1, the difference in Comparative Example 1 is that in step (2), the deposition temperature of the substrate is 500 °C.

[0061] Comparative Example 3 Compared with Example 1, the difference in Comparative Example 1 is that in step (2), the bias voltage applied to the substrate is -200 V.

[0062] Comparative Example 4 Compared with Example 1, the difference in Comparative Example 1 is that in step (2), the deposition gas pressure is 1 Pa.

[0063] Comparative Example 5 Compared with Example 1, the difference in Comparative Example 1 is that in step (3), the deposition time is 120 min.

[0064] Example 6 Compared with Example 1, the difference in Comparative Example 1 is that in step (2), the multi-principal element CrMoNbVHf alloy target is loaded in the deposition chamber of the magnetron sputtering system, and the vacuum in the vacuum chamber is pumped to the background vacuum degree of 1*10 -3 Pa, apply a deposition temperature of 50 °C and a bias voltage of 0 V to the substrate. When the deposition temperature is reached, introduce the working gas argon and the reaction gas nitrogen, and the gas flow ratio Ar:N2 = 1:1. Use the pressure valve to adjust the deposition working gas pressure to 2 Pa.

[0065] II. Test Methods 1. Use Chenhua CHI660E to test the cyclic voltammetry curve of the thin film electrode material at a scanning speed of 10 mV / s, and calculate the specific capacitance per unit area of the electrode material through the formula.

[0066] 2. Use AFM to detect the surface roughness.

[0067] III. Analysis of Test Results of Each Example and Comparative Example (1) The XRD pattern of the multi-principal element (CrMoNbVTi)N thin film obtained in Example 1 is asFigure 1 As shown, the results indicate that (CrMoNbVTi)N is a single solid-solution FCC structure, and the atomic ratios in the prepared (CrMoNbVTi)N thin film are Cr:Mo:Nb:V:Ti:N = 11.9:12.33:11.93:11.22:10.54:42.08. The multi-principal element (CrMoNbVZr)N thin film obtained in Example 2 is a single FCC structure, and the atomic ratios in the prepared (CrMoNbVTi)N thin film are Cr:Mo:Nb:V:Ti:N = 12.01:13.1:12.32:12.44:13.59:36.54. The multi-principal element (CrMoNbVHf)N thin film in Example 3 is a single FCC structure, and the atomic ratios in the prepared (CrMoNbVTi)N thin film are Cr:Mo:Nb:V:Ti:N = 9.12:10.22:10.16:10.56:12.14:47.8, and the element distribution is uniform.

[0068] The SEM image of the multi-principal element (CrMoNbVTi)N thin film obtained in Example 1 is as Figure 2 shown. It can be observed in the image that the agglomeration of grains results in relatively large grain gaps on the surface of the thin film, a relatively high porosity, and a loose thin film structure. During the electro-chemical reaction process, the elements of the thin film electrode can contact the electrolyte ions, providing excellent capacitance.

[0069] The AFM image of the multi-principal element (CrMoNbVTi)N thin film obtained in Example 1 is as Figure 3 shown. The thin film presents an island-like growth type, and the root mean square roughness (R a ) is 9.10 nm. The thin film has a rougher microstructure and surface, with a relatively high pore content and internal surface area.

[0070] The CV diagram of the multi-principal element (CrMoNbVTi)N thin film obtained in Example 1 is as Figure 4 shown. It can be seen from the curve that at high and low scan rates, the morphology of the curve does not change significantly, and the CV curve presents an approximately symmetric rectangular shape, indicating that the prepared multi-principal element nitride thin film has an ideal capacitance behavior. By calculation, it can be obtained that it has an areal specific capacitance of 139.1 mF / cm 2 at a scan rate of 10 mV / s.

[0071] (2) The areal specific capacitances at a scan rate of 10 mV / s in Examples 1 to 3 and Comparative Examples 1 to 5 were detected, and the detection results are shown in Table 1 below.

[0072] Table 1 Detection results of areal specific capacitances of each example and comparative example

[0073] In Comparative Example 1, the vacuum degree is 2×10 -3 Pa. It is speculated that when the vacuum degree is too high, it may cause the oxidation of the thin film, form metal oxides, resulting in a decrease in conductivity, an increase in the internal resistance of the interface, and then hinder electron transport, reduce the electro-chemical reaction efficiency, and thus lead to a decrease in the specific capacitance value of the electrode. In Comparative Example 2, the substrate temperature is too high. At high temperatures, the thin film densifies, and the nano-scale pores decrease, resulting in a decrease in the effective reaction area and a decrease in the specific capacitance value. In Comparative Example 3, the bias voltage applied to the substrate is relatively high, which will introduce high-density defects (such as dislocations and grain boundaries), hinder ion diffusion (such as Li + 、Na + ), and increase the interface impedance. In Comparative Example 4, the deposition gas pressure is lower than 2.5 Pa. The mean free path of the sputtering particles is long and the kinetic energy is high. The formed thin film is denser, the specific surface area is smaller, and the ion diffusion path is long, resulting in a decrease in the specific capacitance; in Comparative Example 5, the deposition time is 120 min, the formed thin film is thicker, the ion diffusion path is long, resulting in an increase in impedance, a decrease in the rate performance, and a decrease in the specific capacitance. The thin film obtained in Example 6 is an amorphous structure, resulting in a significant decrease in its areal specific capacitance.

[0074] In summary, under specific process parameters (deposition temperature 100~300 °C, background vacuum degree 1×10 -3 Pa, deposition working gas pressure 2.5~4 Pa, bias voltage not greater than -100 V, deposition power 100 - 200 W, deposition time 30~90 min), the electrochemical performance of the multi-principal element CrMoNbV-based thin film electrode material prepared is the best.

[0075] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples. Embodiments with the same structure in essence as the technical idea and the same effect within the technical solution scope of this application are all included in the technical scope of this application. In addition, within the scope not departing from the gist of this application, various deformations that those skilled in the art can think of applied to the embodiments and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of this application.

Claims

1. A supercapacitor thin film electrode material, characterized in that It includes a substrate and a multi-principal element nitride thin film adhered to the substrate; the multi-principal element nitride thin film is composed of (CrMoNbVX)N, where X is one of the other transition metal elements except Cr, Mo, Nb, and V; the crystal structure of the multi-principal element nitride thin film is a face-centered cubic structure, and the surface roughness is 9 - 20 nm.

2. The supercapacitor thin film electrode material according to claim 1, characterized in that, The specific capacitance per unit area of the supercapacitor thin film electrode material is greater than or equal to 100 mF / cm² at a current density of 10 mV / s 2 .

3. The supercapacitor thin film electrode material according to claim 1, characterized in that, The substrate is stainless steel or single crystal silicon.

4. A preparation method of the supercapacitor thin film electrode material as described in any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Pretreat the substrate; (2) Deposit a multi-principal element nitride thin film on the pretreated substrate by magnetron sputtering; In the magnetron sputtering, a multi-principal element alloy is used as the target, and the multi-principal element alloy includes Cr, Mo, Nb, V, and X, where X is one of the other transition metal elements except Cr, Mo, Nb, and V, and the molar ratio of Cr, Mo, Nb, V, and X is 1:1:1:1:

1.

5. The preparation method of the supercapacitor thin film electrode material according to claim 4, characterized in that, The process conditions of the magnetron sputtering are as follows: argon is used as the working gas, nitrogen is used as the reaction gas, the air pressure in the vacuum chamber is less than or equal to 1×10 -3 Pa, the DC sputtering power is 100 - 200 W, the substrate bias voltage is 0 - -100 V, the deposition pressure is 2.5 - 4 Pa, the deposition temperature is 100 - 300 °C, and the deposition time is 30 - 90 min.

6. The preparation method of the supercapacitor thin film electrode material according to claim 4, characterized in that, The flow rate ratio of argon to nitrogen is 1:1, and the flow rate of argon is 10 - 150 sccm.

7. The preparation method of the supercapacitor thin film electrode material according to claim 4, wherein, The substrate pretreatment step in the step (1) includes: Ultrasonically clean the substrate successively with acetone, absolute ethanol, and deionized water to obtain a clean substrate; Perform glow cleaning on the clean substrate. The process conditions for the glow cleaning are as follows: Use argon gas at 150 sccm as the working gas, the air pressure in the vacuum chamber is 1*10 -3 Pa, the cleaning time is 10 - 30 minutes, and the substrate bias voltage is 0 to -100 V.

8. The preparation method of the supercapacitor thin film electrode material according to claim 4, characterized in that, Before depositing the multi-principal element nitride thin film on the substrate in the step (2), perform target pre-sputtering to remove impurities on the surface of the target.

9. The preparation method of the supercapacitor thin film electrode material according to claim 8, characterized in that, The process conditions for the target pre-sputtering are: use 50 sccm of argon as the working gas, 50 sccm of nitrogen as the reaction gas, the pre-sputtering power is 50 - 200 W, and the time is 10 - 20 min.

10. The preparation method of the supercapacitor thin film electrode material according to claim 4, wherein In the step (2), the self-rotation speed of the substrate is 10 - 20 r / min.

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