Preparation method of gallium nitride with adjustable interface energy storage active surface, gallium nitride and application

Abstract

The application provides a preparation method of gallium nitride with adjustable interface energy storage active surface, gallium nitride and application. The preparation method comprises the following steps: S1, grinding and mixing melamine, a benzene solution of gallium trichloride and potassium nitrate to obtain a mixture A, wherein n (melamine) = n (gallium trichloride) + n (potassium nitrate), and n represents the amount of substance; S2, transferring the mixture A into a reaction furnace, heating the reaction furnace to 800-850 DEG C under gas protection, naturally cooling to room temperature after heat preservation for 4-7 h, and obtaining a solid B; and S3, washing and drying the solid B to obtain gallium nitride powder. According to the nitrate-mediated carbothermal reduction reaction, the gallium nitride with adjustable interface energy storage active surface is prepared by controlling the reaction time, the preparation method is simple and reliable, and the regulation effect on the interface energy storage active surface of the gallium nitride is remarkable.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrode material preparation and electrochemical energy storage, and relates to a preparation method of gallium nitride with adjustable interface energy storage active surface, gallium nitride and application. BACKGROUND

[0002] The electrochemical performance of electrode materials is affected by the surface atomic structure thereof. For example, the (730), (520) and (210) crystal planes of platinum nanocrystals have a higher density of atomic steps and dangling bonds than the (100), (111) and (110) crystal planes, and exhibit significantly enhanced catalytic activity for the electro-oxidation of small organic fuel molecules (Science 2007, 316, 732). Compared with the Zn(002) crystal plane with a regular hexagonal structure, the (100) and (101) crystal planes of hexagonal metal Zn exhibit enhanced surface energy and reduced dissolution activation energy due to the wavy arrangement of atoms (Energy Storage Mater. 2022, 51, 550). For hexagonal wurtzite gallium nitride (GaN), the (100), (002) and (101) crystal planes are dominant in the XRD spectrum, which means that the atomic arrays constituting the above crystal planes dominate the surface atomic structure of GaN. However, the research on the interface energy storage active surface of GaN and its influence on interface energy storage has not been reported. SUMMARY

[0003] In view of the deficiencies of the prior art, the application provides a preparation method of gallium nitride with adjustable interface energy storage active surface, gallium nitride and application.

[0004] The preparation method of gallium nitride with adjustable interface energy storage active surface uses gallium trichloride as a gallium source, melamine as a nitrogen source, and potassium nitrate as a GaN growth promoter. Through carbonthermal reduction reaction mediated by potassium nitrate and by controlling the reaction time, the interface energy storage active surface of GaN is realized.

[0005] The preparation method of gallium nitride with adjustable interface energy storage active surface comprises the following steps:

[0006] a. Grinding and mixing melamine, a benzene solution of gallium trichloride and potassium nitrate in a certain ratio in a fume hood to obtain a mixture A.

[0007] b. Transferring the mixture A into a crucible and then into a tube furnace.

[0008] c. Raising the temperature of the tube furnace to a reaction temperature under the protection of nitrogen or argon, maintaining the temperature for 4-7 h, and naturally cooling to room temperature to obtain a solid B.

[0009] d. Washing and drying the solid B with distilled water to obtain GaN powder with an adjustable interface energy storage active surface.

[0010] The melamine, gallium trichloride and potassium nitrate in step a, wherein n(melamine) = n(gallium trichloride + potassium nitrate), n represents the amount of substance.

[0011] The benzene solution of gallium trichloride in step a, the gallium chloride is dissolved in benzene for convenient access, and the solution concentration is not particularly limited.

[0012] The gallium trichloride and potassium nitrate in step a, wherein the amount-of-substance ratio of gallium trichloride to potassium nitrate is 4:1.

[0013] The crucible in step b, including but not limited to ceramic crucible, corundum crucible and boron nitride crucible.

[0014] The reaction temperature in step c is 800-850℃, and the heating rate is 5-10℃ / min -1 .

[0015] The drying in step d, wherein the drying temperature is 60-100℃, and the drying time is 4-12h.

[0016] The application also provides the gallium nitride powder prepared by the above method.

[0017] The application also provides the application of the gallium nitride powder, which is used as an electrode material of a supercapacitor working electrode.

[0018] The application also provides a preparation method of a GaN-based working electrode of the gallium nitride powder prepared by the above method, including the following steps:

[0019] An appropriate amount of gallium nitride powder, acetylene black and polyvinylidene fluoride are transferred to an agate mortar, an appropriate amount of N-methyl pyrrolidone is added dropwise, and a slurry is prepared after sufficient grinding, wherein the mass ratio of the gallium nitride powder, acetylene black and polyvinylidene fluoride is 8:1:1.

[0020] The slurry is uniformly coated on a stainless steel wire mesh (current collector), and then placed in a vacuum drying oven and dried at 80℃ for 12h to prepare a GaN-based working electrode.

[0021] The gallium nitride working electrode, wherein the loading amount of gallium nitride (active substance) is 3.5-10mg cm -2 .

[0022] Advantages

[0023] 1. The application provides a preparation method of gallium nitride with adjustable interface energy storage active surface, which takes gallium trichloride as a gallium source, melamine as a nitrogen source and potassium nitrate as a GaN growth promoter, utilizes a carbon thermal reduction reaction mediated by potassium nitrate, and realizes the regulation of the interface energy storage active surface of GaN by controlling the reaction time, so that the method is simple and the regulation of the interface energy storage active surface of GaN is remarkable.

[0024] 2. The gallium nitride prepared by the preparation method has improved crystallinity, and the intensity ratios of (002) to (100), (101) to (100) and (101) to (002) are obviously improved, so that the specific capacity and the rate performance of the interface energy storage are improved, and the gallium nitride has high structural stability. (002) / (100) and I (101) / (100) ) are obviously improved, so that the specific capacity and the rate performance of the interface energy storage are improved, and the gallium nitride has high structural stability.

[0025] 3. According to the technical scheme, under the mediation of potassium nitrate, the heat treatment time is controlled, so that the active surface and the crystallinity of GaN can be regulated, and the surface chemistry and the texture characteristics of GaN can also be regulated.

[0026] 4. The preparation method can regulate the interface energy storage active surface of GaN, so that the GaN can obtain excellent electrochemical performance under the condition of low specific surface and total pore volume.

[0027] 5. The working electrode prepared based on the gallium nitride powder has a gallium nitride (active material) loading capacity of 3.5-10 mg cm -2 , and has excellent electrochemical performance; when the current density is increased from 1 mA cm -2 to 100 mA cm -2 , the capacity retention rate is higher than 60%, and when the current density is 2 mA cm -2 , the capacity retention rate is close to 100% after 10,000 cycles.

[0028] 6. The supercapacitor assembled based on the gallium nitride provided by the application has excellent specific energy-specific power performance under the premise that the electrode loading capacity meets the requirements of commercial supercapacitors for electrode loading capacity, can reliably operate in a wide temperature range of-60-60 DEG C, and is suitable for use in environments with significant temperature changes. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Structure characterization of samples: (a) XRD pattern; (b) crystal plane intensity ratio; (c) Rietveld refinement pattern; (d) Raman spectrum.

[0030] Figure 2 Adsorption energy of H + adsorbed on GaN (100), (002) and (101) crystal planes.

[0031] Figure 3 SEM (a-d) and TEM (e, f) images of samples: (a) S-4; (b) S-1; (c) S-2; (d) S-3; (e, f) S-2.

[0032] Figure 4 Electrochemical performance of sample working electrode under three-electrode system: (a) cyclic voltammetry curve; (b) galvanostatic charge-discharge curve; (c) rate curve; (d) cycle curve; electrolyte is 1M H2SO4, and the loading of GaN on working electrode is 3.5 mg cm -2 .

[0033] Figure 5 Electrochemical performance of WE-2||WE-2 supercapacitor: (a) galvanostatic charge-discharge curve under 1 mA cm -2 ; (b) rate curve; (c) specific energy-specific power graph; (d) cycle curve; (e) galvanostatic charge-discharge curve of device under 5 mA cm -2 at-45℃; (f) galvanostatic charge-discharge curve of device under 5 mA cm -2 at 60℃. DETAILED DESCRIPTION

[0034] The technical solutions of the present application are further described below by means of specific embodiments and in conjunction with the drawings, and these embodiments are only for describing the technical solutions of the present application and cannot be regarded as limiting the content of the claims of the present application.

[0035] The benzene and N-methyl pyrrolidone in the embodiments are purchased from Shanghai Reagent Co., Ltd.; the stainless steel wire mesh, acetylene black and polyvinylidene fluoride are purchased from Taobao Jinghong New Energy; the plant fiber paper (Poetic Silk) is purchased from Hangzhou Youquan E-commerce Co., Ltd.; and the gallium trichloride is self-made by using the combustion reaction of metallic gallium and chlorine.

[0036] The X-ray powder diffraction spectrum (XRD) is obtained by using a German Bruker D8 Advance powder diffractometer; the scanning electron microscope (SEM) photos and element distribution maps are obtained by using a Japanese Hitachi Regulus8220 field emission scanning electron microscope; the Raman spectrum is obtained by using a British Renishaw inVia laser Raman spectrometer; the transmission electron microscope (TEM) photo is obtained by using a Japanese electronic JEOL JEM-2100 high-resolution transmission electron microscope; the X-ray photoelectron spectrum (XPS) is obtained by using an American Fisher Scientific ESCALAB Xi + X-ray photoelectron spectrometer; the nitrogen adsorption-desorption isotherm and pore size distribution are obtained by using an American micromeritics ASAP 2460 full-automatic specific surface and pore size analyzer.

[0037] Theoretical calculation is made based on density functional theory, and the VASP (Vienna ab initio simulation package) program and the projection augmented plane wave method based on the generalized gradient approximation are used.

[0038] The electrochemical performance of the working electrode and the supercapacitor device is obtained by a Shanghai Chenhua CHI760E electrochemical analyzer. The active material loading of the sample electrode is 3.5-10 mg cm -2 , the current collector is a stainless steel mesh, the separator is Poetic Silk plant fiber paper in a two-electrode system, and the electrolyte is 1 mol L -1 H2SO4 and 52wt% H3PO4; in a three-electrode system, the counter electrode is a platinum sheet, the reference electrode is Hg / Hg2SO4, and the electrolyte is 1 mol L -1 H2SO4; in a two-electrode system, the electrolyte is 52wt% H3PO4.

[0039] Example 1

[0040] A preparation method of gallium nitride with adjustable interface energy storage active surface, comprising the following steps:

[0041] a. Grinding and mixing 4 mmol of melamine, 3.2 mL of 1 mol L -1 GaCl3-benzene solution and 0.8 mmol of potassium nitrate in a fume hood to obtain a mixture A.

[0042] b. Transferring the mixture A to a corundum crucible and then to a tube furnace.

[0043] c. Raising the temperature of the tube furnace to 800℃ at a rate of 10℃ / min -1 under nitrogen protection, keeping at 800℃ for 4 h, and naturally cooling to room temperature to obtain a solid B.

[0044] d. Washing the solid B with distilled water and drying at 60℃ for 12 h to obtain a sample S-1.

[0045] Example 2

[0046] A preparation method of gallium nitride with adjustable interface energy storage active surface, comprising the following steps:

[0047] a. Grinding and mixing 4 mmol of melamine, 3.2 mL of 1 mol L -1 GaCl3-benzene solution and 0.8 mmol of potassium nitrate in a fume hood to obtain a mixture A.

[0048] b. Transferring the mixture A to a corundum crucible and then to a tube furnace.

[0049] c. The tube furnace was heated to 800℃ at a rate of 10℃ / min under nitrogen protection -1 , and was kept at 800℃ for 6h, and was naturally cooled to room temperature to obtain solid B.

[0050] d. The solid B was washed with distilled water, and was dried at 80℃ for 6h to obtain sample S-2.

[0051] Example 3

[0052] A preparation method of gallium nitride with adjustable interface energy storage active surface, comprising the following steps:

[0053] a. 4mmol of melamine, 3.2mL of 1mol / L GaCl3-benzene solution, and 0.8mmol of potassium nitrate were ground and mixed in a fume hood to obtain mixture A. -1 GaCl3-benzene solution, and 0.8mmol of potassium nitrate were ground and mixed in a fume hood to obtain mixture A.

[0054] b. The mixture A was transferred to a corundum crucible, and then was transferred to a tube furnace.

[0055] c. The tube furnace was heated to 800℃ at a rate of 5℃ / min under nitrogen protection -1 , and was kept at 800℃ for 7h, and was naturally cooled to room temperature to obtain solid B.

[0056] d. The solid B was washed with distilled water, and was dried at 100℃ for 4h to obtain sample S-3.

[0057] Comparative Example 1

[0058] A preparation method of gallium nitride powder, comprising the following steps:

[0059] a. 3.2mmol of melamine and 3.2mL of 1mol / L GaCl3-benzene solution were ground and mixed in a fume hood to obtain mixture A. -1 GaCl3-benzene solution, and 0.8mmol of potassium nitrate were ground and mixed in a fume hood to obtain mixture A.

[0060] b. The mixture A was transferred to a corundum crucible, and then was transferred to a tube furnace.

[0061] c. The tube furnace was heated to 800℃ at a rate of 10℃ / min under nitrogen protection -1 , and was kept at 800℃ for 6h, and was naturally cooled to room temperature to obtain solid B.

[0062] d. The solid B was washed with distilled water, and was dried at 60℃ for 12h to obtain sample S-4.

[0063] Example 4

[0064] A preparation method of gallium nitride with adjustable interface energy storage active surface, comprising the following steps:

[0065] a. 4 mmol melamine, 3.2 mL 1 mol L -1 GaCl3-benzene solution, 0.8 mmol potassium nitrate were ground and mixed in a fume hood to obtain mixture A.

[0066] b. Mixture A was transferred to a corundum crucible and then to a tube furnace.

[0067] c. The tube furnace was heated to 850℃ at a rate of 10℃ / min under nitrogen protection. -1 and kept at 850℃ for 6 h, and then naturally cooled to room temperature to obtain solid B.

[0068] d. Solid B was washed with distilled water and dried at 80℃ for 6 h to obtain sample S-5.

[0069] Example 5

[0070] A method for preparing a GaN-based working electrode, comprising the following steps:

[0071] a. An appropriate amount of S-1 powder, acetylene black and polyvinylidene fluoride were transferred to an agate mortar, and an appropriate amount of N-methyl pyrrolidone was added, and the mixture was ground thoroughly to obtain a slurry;

[0072] b. The slurry was uniformly coated on a stainless steel wire mesh (current collector), and then placed in a vacuum drying oven and dried at 80℃ for 12 h to obtain working electrode WE-1, and the GaN loading on the working electrode was 3.5 mg cm -2 .

[0073] c. 1 mol L -1 H2SO4 was used as the electrolyte, platinum metal was used as the counter electrode, and Hg / Hg2SO4 electrode was used as the reference electrode to test the electrochemical performance of the working electrode.

[0074] Example 6

[0075] A method for preparing a GaN-based working electrode, comprising the following steps:

[0076] S-1 powder was replaced by S-2, and the rest of the operations were the same as in Example 6 to obtain working electrode WE-2.

[0077] Example 7

[0078] A method for preparing a GaN-based working electrode, comprising the following steps:

[0079] S-1 powder was replaced by S-3, and the rest of the operations were the same as in Example 6 to obtain working electrode WE-3.

[0080] Comparative Example 2

[0081] A method for preparing a GaN-based working electrode, comprising the following steps:

[0082] The S-1 powder is replaced by S-4, and the rest of the operations are the same as in Example 6 to obtain a working electrode WE-4.

[0083] Example 8

[0084] An assembly of a GaN-based symmetric supercapacitor, comprising the following steps:

[0085] a. An appropriate amount of S-2 powder, acetylene black and polyvinylidene fluoride are transferred to a agate mortar, and an appropriate amount of N-methyl pyrrolidone is added dropwise. After grinding, a slurry is prepared;

[0086] b. The slurry is uniformly coated on a stainless steel wire mesh (current collector), and then placed in a vacuum drying oven at 80°C for 12h to obtain a working electrode. The GaN loading on the working electrode reaches 10mg cm -2 .

[0087] c. A R2032 button-type symmetric supercapacitor is assembled by using 52wt% H3PO4 as the electrolyte and Poetic Silk plant fiber paper as the separator.

[0088] Results analysis

[0089] Figure 1 a is the XRD pattern of the sample. From Figure 1 a, it can be found that: (i) in the presence of potassium nitrate, the crystallinity of samples S-1, S-2 and S-3 is significantly improved compared with that of sample S-4 without potassium nitrate; (ii) in the presence of potassium nitrate, the crystallinity of samples S-1, S-2 and S-3 gradually decreases with the extension of the heat treatment time. Compared with S-4, the improvement of the crystallinity of samples S-1, S-2 and S-3 is attributed to the fact that the reaction between melamine and potassium nitrate is an exothermic reaction, which provides additional energy for the growth of GaN. In other words, the presence of potassium nitrate promotes the growth of GaN. The gradual decrease of the crystallinity of samples S-1, S-2 and S-3 is attributed to the thermal decomposition caused by the thermal instability of GaN.

[0090] Compared with S-4, the intensity ratios of (002) to (100), (101) to (100) and (101) to (002) of samples S-1, S-2 and S-3 are obviously improved (002) / (100) and I (101) / (100) Figure 1 ​(b) Given that the (100), (002), and (101) crystal planes dominate in the GaN XRD pattern, this indicates that the GaN crystal planes can be regulated under the mediation of potassium nitrate by controlling the heat treatment time. It should be noted that, with the participation of potassium nitrate, the intensity ratios of the (002) to (100) and (101) to (100) crystal planes of the S-5 sample obtained after holding at 850℃ for 6 h were 2.01 and 2.46, respectively, significantly higher than the 1.34 and 1.46 of S-4. This indicates that, under the mediation of potassium nitrate, the atomic arrangement of the (002) and (101) crystal planes is favorable within the range of 800-850℃.

[0091] Further discoveries were made through Ritterfeld refinement ( Figure 1 c), the ratios (c / a) of the cell parameters c to a for S-1, S-2, S-3, and S-4 are 1.6227, 1.6225, 1.6220, and 1.6219, respectively. This result further demonstrates that the intensity ratio of (002) to (100) can be controlled through the carbothermic reduction reaction mediated by potassium nitrate.

[0092] The Raman spectra of the sample contain values ​​at 250, 420, 559, and 711 cm⁻¹. -1 Four Raman peaks ( Figure 1 d), attributed to the boundary phonon, phonon overtone, E1(TO), and A1(LO), respectively (Chem. Phys. Lett. 2001, 345, 245). In the first-order Raman scattering at the center of the region, the first two peaks are not... As allowed by space groups, their presence indicates the presence of surface defects in the sample (Adv. Funct. Mater. 2004, 14, 464). Compared to S-1 and S-4, the A1(LO) peaks of S-2 and S-3 shift to higher wavenumbers, which is attributed to phonon coupling occurring in their porous structure (Chem. Phys. Lett. 2001, 345, 245).

[0093] To reveal the active facets for energy storage at the GaN interface, theoretical calculations were used to investigate the H-planes of GaN (100), (002), and (101) crystal planes. + The adsorption behavior of H. Theoretical calculations show that H + The adsorption energy on the GaN(002) crystal plane is higher than that on the (101) crystal plane, and much higher than that on the (100) crystal plane. Figure 2 This indicates that: (i) relative to the GaN (100) crystal plane, (002) and (101), especially (002) crystal plane, are the active planes for GaN interface energy storage; (ii) relative to S-4, I in S-1, S-2 and S-3 (002) / (100) and I (101) / (100)The enhancement of the intensity ratio is beneficial to improve the specific capacity and rate performance of the interface energy storage.

[0094] The porous structure of S-2 and S-3 is supported by the SEM test results Figure 3 ). S-1 is composed of agglomerates of nanoparticles with a particle size concentrated in 130-220 nm Figure 3 a), S-2 is composed of hemispheres with a size concentrated in 1.2-2.0 μm Figure 3 b); S-3 is composed of microparticles of bowl-shaped structure, wherein the bowl-shaped structure is composed of nanowire clusters, the nanowires at the edge are thicker, and the nanowires at the center are thinner Figure 3 c). It is easy to judge that the bowl-shaped structure of S-3 comes from the partial decomposition of the hemispheres of GaN shown in Figure 3 b. With the extension of the heat treatment time to 7 h, the bowl-shaped structure of GaN constituting S-3 continues to decompose and fuse together to form a porous structure Figure 3 d).

[0095] The surface defects of the GaN sample are supported by the TEM image results Figure 3 e, f). Figure 3 The lattice fringes with a spacing of 0.244 nm shown in f correspond to the (101) crystal plane of the wurtzite GaN, wherein the lattice fringes at the edge of the GaN crystallite are discontinuous, which confirms the existence of surface defects.

[0096] Under the mediation of potassium nitrate, by controlling the heat treatment time, not only the active surface and crystallinity of GaN can be regulated, but also the surface chemistry and texture properties of the GaN sample can be regulated. Table 1 shows the surface element types and compositions in S-1 to S-4 samples. From Table 1, it can be seen that under the mediation of potassium nitrate, with the extension of the heat treatment time, the contents of Ga-O / Ga-OH and nitrogen defects in the sample gradually increase, and the content of Ga-N component gradually decreases. The increase of the content of nitrogen defects and the decrease of the content of Ga-N component are due to the continuous thermal decomposition of GaN during the heat treatment process. The increase of the content of Ga-O / Ga-OH is due to the thermal chemical reaction of melamine with potassium nitrate, which not only provides additional energy for the reaction, but also causes partial oxidation of the product due to the generation of oxygen.

[0097] Table 1 Peak separation results of Ga 3d, N 1s and O 2p

[0098]

[0099] Table 2 Texture properties of the samples

[0100]

[0101] The specific surface area and pore volume of S-1 to S-4 samples are shown in Table 2. As can be seen from Table 2, under the mediation of potassium nitrate, when the reaction time is 4h, the specific surface area of S-1 is the smallest, only 13.8m 2 g -1 ; as the heat treatment time is prolonged to 6h, the specific surface area of S-2 is the largest, reaching 205.1m 2 g -1 , higher than 166.6m 2 g -1 of S-4; continuing to prolong the reaction time to 7h, the specific surface area of S-3 is reduced to 42.2m 2 g -1 . Among them, the total pore volume of S-1 is the smallest, 0.038cm 3 g -1 .

[0102] In order to verify the influence of GaN active surface regulation on its electrochemical interface energy storage, the electrochemical performance of the working electrode was first tested by a three-electrode system( Figure 4 ). Figure 4 a is the cyclic voltammogram of the working electrode, and the curve is rectangular, indicating that the interface energy storage of GaN is mainly in the form of electrochemical double layer capacitance. The oxidation / reduction peak located at 0-0.065 / -(0.14-0.026) V indicates that the pseudo-capacitance contributed by the Faraday reaction also contributes to the specific capacity of the electrode. Under a current density of 1mA cm -2 , the discharge specific capacity of the working electrodes WE-1, WE-2, WE-3 and WE-4 is 61, 91, 50 and 35mF cm -2 ( Figure 4 b), respectively; wherein the charge-discharge curve is an isosceles triangle, indicating that the coulombic efficiency during the charge-discharge process is close to 100%. It is worth noting that under all current densities, the discharge specific capacity of the four electrodes is in the order of WE-2>WE-1>WE-3>WE-4( Figure 4 c). This shows that through active surface regulation, the electrochemical performance of the GaN electrode is significantly improved. In addition, the four electrodes are cycled 10,000 times at a current density of 2mA cm -2 , and the capacity retention rate is close to 100%( Figure 4 d); this is due to the high structural stability of GaN.

[0103] From the appearance, the better electrochemical performance of WE-2 is attributed to its higher specific surface area and total pore volume, which can provide more interface energy storage active sites and electrolyte accommodation space. However, although the specific surface area and total pore volume of GaN S-1 in WE-1 are obviously smaller than those of GaN S-4 in WE-4, the former has obviously better discharge specific capacity, rate capability and capacity retention than the latter. This indicates that, in addition to the specific surface area and total pore volume, the active surface and crystallinity of GaN have important influences on the electrochemical performance of its interface energy storage, because S-1 has the highest I (002) / (100) and the strongest crystallinity Figure 1 a,b), more importantly, the (002) surface of GaN has higher activity + for the adsorption of H Figure 2 .

[0104] To verify the feasibility of the active surface regulated GaN provided by the present application in practical applications, WE-2 with higher discharge specific capacity was used as the working electrode, the loading amount of GaN on the working electrode was 10 mg cm -2 , which meets the requirement of the loading amount of working electrode for commercial supercapacitors, 52wt% H3PO4 was used as the electrolyte, and Poetic Silk plant fiber paper was used as the separator to assemble a symmetric supercapacitor. At 1 mA cm -2 , with the temperature increasing from -60 °C to 45 °C and then to 60 °C, the discharge specific capacity of the single device increased from 71 mF cm -2 to 351 mF cm -2 and then decreased to 246 mF cm -2 ( Figure 5 a). With the increase of current density, the order of the discharge specific capacity changing with temperature remained unchanged ( Figure 5 b). At -45 °C, the discharge specific capacity of the device at 10 mA cm -2 was 53 mF cm -2 ; at -60 °C, the discharge specific capacity of the device at 5 mA cm -2 could still be maintained at 53 mF cm -2 . Considering that the tap density of GaN S-2 was 5.23 g cm -3 , the volume discharge specific capacity of the device at -60 °C, room temperature, 60 °C and 1 mA cm -2 was 37, 93 and 129 F cm -3 , respectively. The higher specific capacity and rate capability of the device made it exhibit excellent specific energy-specific power (E-P) performance ( Figure 5 c). At a specific power of 750 μW cm -2 and 392.2 W L -1 ​​​In this case, the specific energy of the device can reach 109.7 μWh cm -2 and 57.4 W h L -1 ; even at a high specific power of 75 mW cm -2 and 39.2 kW L -1 , the specific energy of the device can still reach 27.2 μW h cm -2 and 14.2 W h L -1 . The E-P performance of the supercapacitor assembled by the GaN prepared by the active surface regulation method of the application is superior to or comparable to that of the active carbon (AC) || MnO2 (Adv. Funct. Mater. 2014, 24, 3953), carbon nanorod (CNR) || MnO2 (Adv. Funct. Mater. 2016, 26, 7766) supercapacitor, or the supercapacitor based on carbon nanotubes (CNTs) (ACS Sustainable Chem. Eng. 2019, 7, 7728), gallium oxynitride (GON) @ carbon cloth (Chem. Eng. J. 2021, 411, 128481), GaN nanowire @ graphite paper (Gr) (Small 2017, 13, 1603330), TiN-Fe2N (Adv. Mater. 2015, 27, 4566), TiN (Adv. Sci. 2015, 3, 1500299), porous tungsten oxynitride (WON) (Adv. Mater. 2015, 27, 3085), TiN paper (Nano-Micro Lett. 2019, 12, 3), and Fe2N @ Ti2N (Nano Energy 2016, 26, 1) Figure 5 c).

[0105] Under the condition of continuously changing the current density from 1 to 10, 20 and back to 1 mA cm -2 , the discharge specific capacity of the device can be maintained at 90, 179 and 349 mF cm -2 , respectively, after 21,000 cycles at -45, 25 and 45 ℃, and the capacity retention rates are close to 100%. Under the condition of continuously changing the current density from 1 to 10, 20 and back to 1 mA cm -2 , the discharge specific capacity of the device can still be maintained at 228 mF cm -2 after 10,000 cycles at 60 ℃, and the capacity retention rate is 95% Figure 5 d).

[0106] At -45 and 60 ℃, three identical devices are connected in series and in parallel, respectively, to obtain an output voltage of 4.5 V and a discharge specific capacity of 3 times, respectively Figure 5 e, f).

[0107] Through electrochemical performance analysis of the device, the following conclusions can be drawn: (1) under the premise that the electrode load meets the requirements of commercial supercapacitors for electrode load, the supercapacitor device based on GaN active surface regulation has excellent E-P performance; (2) with 52wt% H3PO4 as an electrolyte, the supercapacitor device can reliably operate in a wide temperature range of-60-60℃ and extreme environmental conditions.

[0108] In summary, the method for regulating the energy storage active surface of GaN provided by the application can enable GaN to obtain excellent electrochemical performance under the condition of low specific surface area and total pore volume, and the symmetric supercapacitor assembled based on GaN active surface regulation not only has high E-P performance, but also can reliably operate in an environment with significant temperature changes.

Claims

1. A method for preparing gallium nitride with tunable interfacial energy storage active surface, characterized in that, Includes the following steps: S1, melamine, gallium trichloride in benzene solution and potassium nitrate are ground and mixed to obtain mixture A, where n(melamine) = n(gallium trichloride) + n(potassium nitrate), and n represents the amount of substance; S2, transfer mixture A to the reactor, heat the reactor to 800-850℃ under gas protection, hold for 4-7 hours, and then cool naturally to room temperature to obtain solid B; S3. After washing and drying solid B, gallium nitride powder is obtained.

2. The method for preparing gallium nitride with tunable interfacial energy storage active surface according to claim 1, characterized in that, In step S1, the molar ratio of gallium trichloride to potassium nitrate is 4:

1.

3. The method for preparing gallium nitride with tunable interfacial energy storage active surface according to claim 1, characterized in that, In step S2, the heating rate of the reactor is 5-10℃ / min. -1 .

4. The method for preparing gallium nitride with tunable interfacial energy storage active surface according to any one of claims 1 to 3, characterized in that, In step S3, solid B is thoroughly washed with distilled water, and the drying temperature is 60-100℃ for 4-12 hours.

5. The method for preparing gallium nitride with tunable interfacial energy storage active surface according to claim 4, characterized in that, In step S2, mixture A is transferred to a crucible and then to a reaction furnace; nitrogen or argon is used for gas protection.

6. The method for preparing gallium nitride with tunable interfacial energy storage active surface according to claim 5, characterized in that, The crucible can be any one of a ceramic crucible, a corundum crucible, or a boron nitride crucible, and the reaction furnace is a tube furnace.

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