Surface site and interlayer structure coupled pinned layered manganese oxide electrode material, preparation method and application thereof

Abstract

The present invention discloses a surface-site and interlayer-structure coupled pinned layered manganese oxide electrode material, its preparation method and application, belonging to the technical field of energy storage materials. First, a metal-ion Mo-pinned layered manganese oxide precursor is prepared by a hydrothermal method, and then the precursor is treated by the plasmon effect of a laser to obtain a metal-ion Mo-pinned layered manganese oxide rich in oxygen defects. Finally, in an anion environment, the metal-ion Mo-pinned layered manganese oxide rich in oxygen defects is treated again by the plasmon effect of a laser to obtain a surface-site and interlayer-structure coupled pinned layered manganese oxide electrode material. The preparation method of the present invention changes the charge distribution environment around the atoms in the MnO2 bulk phase and regulates the width of its Hubbard band gap, thereby enabling it to have a suitable work function. When used as a positive electrode material for an aqueous zinc-ion battery, it can significantly improve the reaction activity and cyclic structural stability of MnO2.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage materials, and particularly relates to a surface site and interlayer structure coupled pinned layered manganese oxide electrode material, a preparation method thereof, and an application thereof. Background Art

[0002] At present, the most widely used energy storage systems are mainly lithium-ion and sodium-ion batteries. However, the defects of flammability, explosiveness, insufficient storage capacity of lithium / sodium metal anodes, and high cost limit their application and development process. Therefore, there is an urgent need to seek alternative products. Aqueous zinc-ion batteries (AZIBs) use zinc, which is abundant in reserves, inexpensive, and relatively stable, as the working ion, and water as the electrolyte solvent. They are favored by researchers at home and abroad due to the advantages of easy availability of raw materials, low cost, easy recycling, good cycle performance, and high energy density / power density, and have become one of the most promising alternatives to organic battery systems such as lithium-ion / sodium-ion batteries. As an important carrier for energy storage, the selection of electrode materials has become an important scientific problem currently faced.

[0003] Manganese dioxide (MnO 2 ) has become one of the most promising cathode materials for aqueous zinc-ion batteries due to its comprehensive advantages such as low cost, high theoretical capacity (single electron capacity of 380 mAh / g), good environmental compatibility, and relatively high discharge platform (1.35V). Among many MnO 2 crystal types, δ-MnO 2 is considered the most ideal manganese-based aqueous zinc-ion battery material due to its two-dimensional layered crystal structure and sufficient ion (~7Å) transport channels. However, during the reversible ion storage process, it still faces side reactions such as manganese ion dissolution caused by the Jahn-Teller effect and phase transformation caused by insufficient ion storage capacity and poor structural stability caused by interlayer structure slippage. Currently, to solve the above scientific problems, common modification methods include defect construction, ion doping (anions, cations), etc. Among them, cations such as metal ions Cu / Ni / K / Na can effectively act as δ-MnO 2 interlayer pillar structures to inhibit interlayer slippage. Defect engineering mainly improves the energy storage site activity and diffusion kinetics process of MnO 2 -based electrode materials, such as oxygen defect and cation defect engineering. The above regulation means are relatively single and cannot simultaneously solve the problems of low capacity storage ability and poor structural stability faced by layered MnO 2 -based electrode materials. If metal ion interlayer construction and defect engineering are simultaneously introduced into the layered MnO 2 bulk phase, and the synergistic effect of the two modification means is combined to improve the ion storage ability of layered MnO 2 and achieve a fast kinetic process, the ion storage ability of MnO 2The intrinsic conductivity and charge / mass transfer efficiency are improved, and the structural stability of MnO is enhanced by the pillar effect of metal cations. When used as the cathode material for aqueous zinc-ion batteries, it exhibits excellent electrochemical performance. However, the presence of oxygen defects can change the bond energy of the Mn-O bonds in MnO, and the bond energy of some Mn-O bonds is weakened. In a water molecule environment, the H in water will combine with the oxygen atoms in MnO to form groups such as hydroxyl (-OH), thereby promoting the cleavage of the Mn-O bonds and making it easier for Mn ions to dissolve out from the crystal structure of MnO, resulting in the gradual erosion of the structure of MnO and a decrease in stability. As the Mn ions continue to dissolve, the crystal structure of MnO will be continuously damaged, and ultimately, the entire structure may collapse. Moreover, the methods for constructing defect engineering usually involve high-temperature calcination, electrochemical treatment, mechanical ball milling, hydrothermal treatment, etc. These methods for regulating oxygen defects either use high-temperature conditions or explosive reducing gases, with complex processes, high energy consumption, and high risks. Additionally, impurities and by-products are inevitably introduced, which is not conducive to the pure and high-performance regulation of oxygen defects in manganese dioxide nanomaterials. The patent with application number CN202210550295.4 discloses a manganese oxide ultrafine nanopowder with oxygen defects on high-index crystal planes, its preparation method, and applications. The patent with application number CN202210267245.5 discloses a preparation method for an oxygen-deficient ε-MnO / carbon quantum dot composite film. The above patents have obtained manganese oxide films or particles with oxygen defects through hydrothermal methods or electrochemical treatment, but there are no reports on the induction of oxygen defects in layered manganese oxide. Therefore, a simple, green, safe, and reasonable method for regulating the oxygen defect component of the micro-nano composite structure with cation pinning of the MnO interlayer structure is needed. 2 Structural stability, and it has excellent electrochemical performance when used as the cathode material for aqueous zinc-ion batteries. However, the existence of oxygen defects will cause changes in the bond energy of the Mn-O bonds in MnO, and the bond energy of some Mn -O bonds is weakened. In a water molecule environment, the H in water 2 will combine with the oxygen atoms in MnO + to form groups such as hydroxyl (-OH), thereby promoting the cleavage of the Mn-O bonds and making it easier for Mn 2 ions to dissolve out from the crystal structure of MnO 2+ , resulting in the gradual erosion of the structure of MnO 2 and a decrease in stability. As the Mn ions continue to dissolve, the crystal structure of MnO 2 will be continuously damaged, and ultimately, the entire structure may collapse. Moreover, the means for constructing defect engineering usually adopt methods such as high-temperature calcination, electrochemical treatment, mechanical ball milling, and hydrothermal treatment. The above methods for regulating oxygen defects either use high-temperature conditions or explosive reducing gases, with complex processes, high energy consumption, and high risks, and inevitably introduce impurities and by-products, which is not conducive to the pure and high-performance regulation of oxygen defects in manganese dioxide nanomaterials. The patent with application number CN202210550295.4 discloses a manganese oxide ultrafine nanopowder with oxygen defects on high-index crystal planes, its preparation method, and applications. The patent with application number CN202210267245.5 discloses a preparation method for an oxygen-deficient ε-MnO 2 / carbon quantum dot composite film. The above patents have obtained manganese oxide films or particles with oxygen defects through hydrothermal methods or electrochemical treatment, but there are no reports on the induction of oxygen defects in layered manganese oxide. Therefore, a simple, green, safe, and reasonable method for regulating the oxygen defect component of the micro-nano composite structure with cation pinning of the MnO 2 interlayer structure is needed. 2 interlayer structure. Summary of the Invention

[0004] Aiming at the above-mentioned prior art, the object of the present invention is to provide a surface site and interlayer structure coupled pinned layered manganese oxide electrode material, its preparation method, and applications. The present invention uses the laser plasmon effect to construct a micro-nano composite structure with anion-pinned oxygen defects coupled with metal ion-pinned layered MnO 2 interlayer, and regulates the charge distribution environment around the atoms in the MnO 2 bulk phase and its Hubbard band gap width by means of two modification methods, so as to make it have a suitable work function. Improve the charge / mass transfer efficiency of MnO while enhancing its structural stability and electrochemical stability, and when used as the cathode material for aqueous zinc-ion batteries, it can significantly improve the performance of MnO 2 . 2Reactivity and cyclic structural stability.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, there is provided a method for preparing a surface-site and interlayer-structure coupled pinned layered manganese oxide electrode material, comprising the following steps:

[0007] (1) Dissolve manganese salt and molybdenum salt in deionized water in sequence, and perform hydrothermal reaction to obtain a metal-ion Mo-pinned layered manganese oxide precursor;

[0008] (2) Under a protective atmosphere, irradiate the metal-ion Mo-pinned layered manganese oxide precursor with a plasmon laser to obtain MnO pinned with oxygen-deficient metal ions Mo 2 ;

[0009] (3) Irradiate the MnO pinned with oxygen-deficient metal ions Mo 2 with a plasmon laser in an anion source to obtain a surface-site and interlayer-structure coupled pinned layered manganese oxide electrode material.

[0010] Preferably, in step (1), the manganese salt includes KMnO 4 and MnSO 4 ·H 2 O; the molybdenum salt is H 24 Mo 7 N 6 O 24 ·4H 2 O; the molar ratio of KMnO 4 , MnSO 4 ·H 2 O and H 24 Mo 7 N 6 O 24 ·4H 2 O is 1:0.15:0.003 - 0.01.

[0011] Preferably, in step (1), the temperature of the hydrothermal reaction is 120 - 160 °C, and the time of the hydrothermal reaction is 10 - 16 h.

[0012] Preferably, in step (1), after the hydrothermal reaction is completed, filter and wash to obtain a precipitate, and perform vacuum freeze-drying on the precipitate to obtain a metal-ion Mo-pinned layered manganese oxide precursor.

[0013] The washing is 3 - 8 times of rinsing with deionized water, and then 2 - 5 times of rinsing with ethanol. The freeze-drying temperature is -80 ~ -40 °C, and the freeze-drying time is 12 h.

[0014] Preferably, in steps (2) and (3), the parameters of the plasmon laser are as follows: the line spacing is 0.001 - 0.004 mm, the laser scanning speed is 200 - 500 mm / s, and the laser power is 30% - 40%.

[0015] Preferably, in step (3), the anion source is ammonia gas or sulfur powder; when the anion source is ammonia gas, the reaction environment is filled with ammonia gas; when the anion source is sulfur powder, the reaction environment is filled with a protective gas.

[0016] Preferably, the mass ratio of the oxygen - deficient metal ion Mo - pinned MnO 2 and sulfur powder is 10:1; the mass ratio of the oxygen - deficient metal ion Mo - pinned MnO 2 and ammonia gas is 1:3 - 6.

[0017] Preferably, the protective gas is argon gas.

[0018] In the second aspect of the present invention, there is provided a surface - site and interlayer - structure - coupled pinned layered manganese oxide electrode material obtained by the above - mentioned preparation method. The surface - site and interlayer - structure - coupled pinned layered manganese oxide electrode material is a layered MnO 2 .

[0019] Specifically, the structure of the surface - site and interlayer - structure - coupled pinned layered manganese oxide electrode material is as follows: Mo is located in the middle layer of the layered MnO 2 , and the layered MnO 2 contains partial oxygen defects and a part of the oxygen defects are filled with anions.

[0020] Preferably, the doping amount of Mo is 3 wt%; the doping amount of the anion is 6 wt%; the anion is S 2- or N 3- .

[0021] In the third aspect of the present invention, there is provided an application of the surface - site and interlayer - structure - coupled pinned layered manganese oxide electrode material in specific capacity and cycle stability.

[0022] The beneficial effects of the present invention:

[0023] (1) The surface - site and interlayer - structure - coupled pinned layered manganese oxide electrode material constructed by the present invention utilizes anion - pinned oxygen defects to couple with metal - ion - pinned layered MnO 2 , regulates the atomic charge distribution in the bulk phase of MnO 2 , reduces the Hubbard band gap, and enables it to have a suitable work function, thereby improving the charge / mass transfer efficiency of MnO 2 . At the same time, by means of anion - pinned oxygen defects, the migration and aggregation of oxygen defects are inhibited, and the MnO2 The lattice structure effectively prevents the weakening of the Mn-O bond caused by oxygen defects and reduces the dissolution of Mn 2 + ; and the pinning pillars between the metal cation MnO 2 layers prevent their interlayer slip, overall improving the structural stability of MnO 2 . Therefore, when used as the cathode material for aqueous zinc-ion batteries, it can achieve the storage of fast-reversible zinc ions, endowing the layered manganese oxide electrode material with fast kinetic processes, high reversible charge-discharge cycle capacity, and long cycle life.

[0024] (2) The preparation method adopted in the present invention is simple, the reaction process is non-toxic and pollution-free, the preparation cost is low, the raw materials are rich in sources, and it can be used for industrial production. Laser treatment to construct oxygen vacancies or laser treatment to construct anion-pinned oxygen vacancies. This preparation method can effectively avoid the phase transformation caused by constructing oxygen defects in the layered manganese oxide structure by the traditional calcination method, and the preparation method has universality and the potential for batch production. Brief Description of the Drawings

[0025] Figure 1 : (a) Scanning electron microscope image of layered MnO 2 ; (b) Scanning electron microscope image of Mo-MnO prepared in step (1) of Example 1 2 ; (c) Scanning electron microscope image of Ov-Mo-MnO prepared in step (2) of Example 1 2 ; (d) Scanning electron microscope image of N / Ov-Mo-MnO prepared in Example 1 2 ; (e) Scanning electron microscope image of S / Ov-Mo-MnO prepared in Example 2 2 ;

[0026] Figure 2 : (a) Transmission electron microscope image of layered MnO 2 ; (b) Transmission electron microscope image of Mo-MnO prepared in step (1) of Example 1 2 ; (c) Transmission electron microscope image of Ov-Mo-MnO prepared in step (2) of Example 1 2 ; (d) Transmission electron microscope image of N / Ov-Mo-MnO prepared in Example 1 2 ; (e) Transmission electron microscope image of S / Ov-Mo-MnO prepared in Example 2 2 ;

[0027] Figure 3 : (a) Scanning electron microscope image of Comparative Example 1; (b) Scanning electron microscope image of Comparative Example 2; (c) Scanning electron microscope image of Comparative Example 3; (d) Scanning electron microscope image of Comparative Example 4; (e) Scanning electron microscope image of Comparative Example 5;

[0028] Figure 4 : (a) XPS spectra of N element distribution at different etching depths; (b) XPS spectra of oxygen defect distribution at different etching depths; (c) MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 's EPR spectra.

[0029] Figure 5 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 's XRD patterns;

[0030] Figure 6 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 's band gap width and the position of the Fermi level;

[0031] Figure 7 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 's work function values;

[0032] Figure 8 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 's adsorption energy magnitude for Zn 2+ / H + ;

[0033] Figure 9 : (a) Adsorption energy magnitude of MnO 2 for water; (b) Adsorption energy magnitude of Mo-MnO 2 for water; (c) Adsorption energy magnitude of Ov-Mo-MnO 2 for water; (d) N / Ov-Mo-MnO2 Magnitude of the adsorption energy for water; (e) S / Ov-Mo-MnO 2 Magnitude of the adsorption energy for water;

[0034] Figure 10 : (a) MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 CV curves of; (b) MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 Charge-discharge curves of; (c) CV curves of Comparative Examples 1-5; (d) Charge-discharge curves of Comparative Examples 1-5;

[0035] Figure 11 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 Long cycle performance at a current density of 1 A g -1 ;

[0036] Figure 12 : MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 Dissolution of Mn 2+ under different numbers of cycles;

[0037] Figure 13 : (a) Galvanostatic Intermittent Titration Technique (GITT) images of MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 ; (b) MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2Mn in the middle 2+ Migration energy barrier;

[0038] Figure 14 : Schematic diagram of the action principle of the surface site and interlayer structure coupled pinned layered manganese oxide electrode material in an aqueous zinc-ion battery. Detailed implementation mode

[0039] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, 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 the present application belongs.

[0040] As introduced in the background art section, the energy storage active site capacity output ability of layered manganese oxide is insufficient and its structural stability is relatively low, thus restricting its application in charge / mass transfer performance. And during the H + and Zn 2+ insertion / extraction process, phase transformation is likely to occur, and these problems will affect the capacity output ability of the electrode material and reduce its cycle life.

[0041] Based on this, the purpose of the present invention is to provide a surface site and interlayer structure coupled pinned layered manganese oxide electrode material, its preparation method and application. The present invention first prepares a metal Mo-pinned layered MnO 2 precursor by hydrothermal synthesis method. Then, the metal Mo-pinned layered MnO 2 precursor is treated with laser to obtain a metal Mo-pinned layered MnO 2 rich in oxygen defects. Finally, the metal Mo-pinned layered MnO 2 is tiled at the bottom of a porcelain boat, and in a specific atmosphere / anion source environment, it is irradiated with a plasmon laser and the sputtered powder is collected to obtain a surface site and interlayer structure coupled pinned layered manganese oxide electrode material, which is an anion-pinned oxygen defect coupled metal ion-pinned layered MnO 2 micro-nano composite structure. It is mixed with carbon powder and binder, N-methylpyrrolidone is added, and ground evenly to obtain a viscous electrode paste. The viscous electrode paste is evenly coated on a substrate titanium foil and dried in a vacuum drying oven to obtain a loaded anion-pinned oxygen defect coupled metal ion-pinned layered MnO 2 electrode sheet.

[0042] The present invention utilizes the plasmon laser effect of laser to obtain a metal Mo-pinned layered MnO 2 rich in oxygen defects and a layered MnO 2 with anion partially pinned (filled) oxygen defects. In an aqueous environment, oxygen defects can regulate the electronic structure, increase conductivity, and oxygen defects can increase ion storage sites and improve the specific capacity of the positive electrode. However, if there are too many oxygen defects, water molecules attack the oxygen defects, causing Mn4+ Dissolution affects the performance of aqueous batteries; therefore, it is necessary to control the amount of oxygen vacancies. Thus, it is necessary to fill some of the oxygen vacancies with anions and control the amount of oxygen vacancies with anions. Therefore, the filling amount of anions has a great influence on the performance of the final material. If the doping amount of anions is too large, the MnO 2 material will undergo a phase change, such as becoming MnS 2 ; if the doping amount of anions is too small, the anions cannot fill into the oxygen vacancies. In addition, the laser processing parameters of the laser plasmon effect also affect the performance of the material: if the power is too large, the MnO 2 material will undergo a phase change and the valence state of the anions will change; if the power is too small, the anions cannot fill into the oxygen vacancies.

[0043] As Figure 14 shown, in the layered MnO 2 composite material prepared by the present invention, the oxygen vacancies generated under the action of laser and the backfilled anions are uniformly distributed in the manganese oxide matrix phase. By using anions to pin oxygen vacancies and coupling metal ions to pin the layered MnO 2 , the charge distribution around the atoms in the MnO 2 matrix phase is regulated, the Hubbard band gap is reduced, and it has a suitable work function, thereby improving the MnO 2 charge / mass transfer efficiency. At the same time, by means of anions pinning oxygen vacancies, the migration and aggregation of oxygen vacancies are inhibited, the lattice structure of MnO 2 is stabilized, the weakening of the Mn-O bond caused by oxygen vacancies is effectively prevented, and the dissolution of Mn 2+ is reduced; and the pinning pillars between the layers of metal cations and MnO 2 prevent the interlayer slip, and the structural stability of MnO 2 is improved as a whole. When it is used as the positive electrode material of an aqueous zinc ion battery, rapid and reversible zinc ion storage can be realized, endowing the layered manganese oxide electrode material with a rapid kinetic process, a high reversible charge-discharge cycle capacity, and a long cycle life.

[0044] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with specific embodiments.

[0045] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0046] Example 1: Preparation of N / Ov-Mo-MnO 2

[0047] (1) Using the hydrothermal synthesis method, add 200 mg of KMnO 4 and 39.2 mg of MnSO 4 ·H​2 O, add 30 ml of deionized water and stir until dissolved to form Solution ①. Then add 10 mg of H 24 Mo 7 N 6 O 24 ·4H 2 O into Solution ① and stir until dissolved to obtain Solution ②. Place the reaction kettle containing Solution ② in an oven and keep it at 160 °C for 16 h. After the reaction kettle cools down, collect the sample, wash it three times with deionized water and ethanol, and then freeze-dry it at -60 °C for 24 h to obtain metal ion Mo-pinned layered MnO 2 powder, denoted as Mo-MnO 2 .

[0048] (2) Take 100 mg of Mo-MnO 2 and place it at the bottom of a corundum boat with a size of 2 cm × 2 cm. Put the boat in a glass reactor (the reactor cover is a quartz sheet with a thickness of 4 mm), introduce argon for 10 min to exhaust the air in the reactor, and use an HTF50M laser marking machine (set the scanning speed to 500 mm / s, the power to 35%, the line spacing to 0.002 mm, and the number of scanning circles to 3) to scan the powder. After the scanning is completed, collect the sputtered powder to obtain manganese dioxide powder with oxygen-deficient defects pinned by metal ion Mo; denoted as Ov-Mo-MnO 2 .

[0049] (3) Take 100 mg of Ov-Mo-MnO 2 and place it at the bottom of a corundum boat with a size of 2 cm × 2 cm. Put the boat in a glass reactor (the reactor cover is a quartz sheet with a thickness of 4 mm, the diameter of the reactor is 8 cm, and the height is 5.6 cm), introduce ammonia for 10 min to exhaust the air in the reactor, control the flow rate to 1 cm 3 / s, and use an HTF50M laser marking machine (set the scanning speed to 500 mm / s, the power to 35%, the line spacing to 0.002 mm, and the number of scanning circles to 3) to scan the powder. After the scanning is completed, collect the sputtered powder to obtain anion N-pinned oxygen vacancy-coupled metal ion Mo-pinned layered manganese dioxide powder. Denoted as N / Ov-Mo-MnO 2 .

[0050] Example 2: Preparation of S / Ov-Mo-MnO 2

[0051] (1) Using the hydrothermal synthesis method, add 200 mg of KMnO 4 and 39.2 mg of MnSO 4 ·H 2 ​O, add 30 ml of deionized water and stir until dissolved to form Solution ①. Then, add 15 mg of H 24 Mo 7 N 6 O 24 ·4H 2 O into Solution ① and stir until dissolved to obtain Solution ②. Place the reaction kettle containing Solution ② in an oven and keep it at 160 °C for 16 h. After the reaction kettle cools down, collect the sample, wash it three times with deionized water and ethanol, and then freeze-dry it at -60 °C for 24 h to obtain metal ion Mo-pinned layered MnO 2 powder, denoted as Mo-MnO 2 .

[0052] (2) Take 100 mg of Mo-MnO 2 and place it at the bottom of a corundum boat with a size of 2 cm × 2 cm. Put the boat in a glass reactor (the reactor cover is a quartz sheet with a thickness of 4 mm), introduce argon for 10 min to exhaust the air in the reactor, and use an HTF50M laser marking machine (set the scanning speed to 500 mm / s, the power to 35%, the line spacing to 0.002 mm, and the number of scanning circles to 3) to scan the powder. After the scanning is completed, collect the sputtered powder to obtain manganese dioxide powder pinned by oxygen-deficient metal ion Mo; denoted as Ov-Mo-MnO 2 .

[0053] (3) Take 100 mg of Ov-Mo-MnO 2 and place it in a mortar. Add 10 mg of sulfur powder to it and grind the two evenly to obtain a mixed powder. Place the mixed powder at the bottom of a corundum boat with a size of 2 cm × 2 cm. Put the boat in a glass reactor (the reactor cover is a quartz sheet with a thickness of 4 mm), introduce argon for 10 min to exhaust the air in the reactor, and use an HTF50M laser marking machine (set the scanning speed to 500 mm / s, the power to 35%, the line spacing to 0.002 mm, and the number of scanning circles to 3) to scan the powder. After the scanning is completed, collect the sputtered powder to obtain anion S-pinned oxygen-deficient coupled metal ion Mo-pinned layered manganese dioxide powder. Denoted as S / Ov-Mo-MnO 2 .

[0054] Comparative Example 1

[0055] The difference from Example 1 is that in step (3), the power of the HTF50M laser marking machine is 20%, and finally, anion N-pinned oxygen vacancy coupled metal ion Mo-pinned layered manganese dioxide powder is prepared. Denoted as N-Mo-MnO 2 -20%.

[0056] Comparative Example 2

[0057] The difference from Example 1 is that in step (3), the power of the HTF50M laser marking machine is 50%, and finally, anion N-pinned oxygen vacancy coupled with metal ion Mo-pinned layered manganese dioxide powder is prepared. It is denoted as N-Mo-MnO 2 -50%.

[0058] Comparative Example 3

[0059] The difference from Example 1 is that in step (3), the number of scanning circles of the HTF50M laser marking machine is 6, and finally, anion N-pinned oxygen vacancy coupled with metal ion Mo-pinned layered manganese dioxide powder is prepared. It is denoted as N-Mo-MnO 2 -6.

[0060] Comparative Example 4

[0061] The difference from Example 2 is that in step (3), the mass ratio of Mo-MnO 2 to sulfur powder is 5:1, and finally, anion S-pinned oxygen vacancy coupled with metal ion Mo-pinned layered manganese dioxide powder is prepared. That is S -Mo-MnO 2 -5.

[0062] Comparative Example 5

[0063] The difference from Example 2 is that in step (3), the mass ratio of Mo-MnO 2 to sulfur powder is 15:1, and finally, anion S-pinned oxygen vacancy coupled with metal ion Mo-pinned layered manganese dioxide powder is prepared. That is S -Mo-MnO 2 -15.

[0064] Test Example 1: Characterization

[0065] For MnO 2 , Mo-MnO prepared in step (1) of Example 1 2 , Ov-Mo-MnO prepared in step (2) of Example 1 2 , N / Ov-Mo-MnO prepared in Example 1 2 , S / Ov-Mo-MnO prepared in Example 2 2 , N-Mo-MnO prepared in Comparative Example 1 2 -20%, N-Mo-MnO prepared in Comparative Example 2 2 -50%, N-Mo-MnO prepared in Comparative Example 3 2 -6, S -Mo-MnO prepared in Comparative Example 4 2 -5 and S -Mo-MnO prepared in Comparative Example 5 2 -15 were characterized.

[0066] AsFigures 1 - 2 As shown, the anion-nailed oxygen-deficient coupled metal ion Mo-nailed layered manganese dioxide prepared in Examples 1-2 is in the form of nanosheet microspheres. Compared with the original MnO 2 , the Mo-MnO prepared in step (1) of Example 1 2 basically does not change the morphology of MnO 2 . In the Ov-Mo-MnO prepared in step (2) of Example 1 2 , there are some damages in the nanosheet microstructure. The transmission electron microscope scanning image shows that the nanospheres composed of nanosheets have agglomeration phenomena. This is because too many oxygen defects cause lattice vacancies or interstitial atoms, leading to lattice distortion and internal stress, which in turn affect the structural stability of the nanosheets, resulting in local deformation and dislocation of the microstructure and causing structural loss.

[0067] Compared with Ov-Mo-MnO 2 , the nanosheet microstructure of the N / Ov-Mo-MnO prepared in Example 1 2 has no obvious damage. The transmission electron microscope scanning image shows that the nanosphere structure is complete. For the S / Ov-Mo-MnO prepared in Example 2 2 , although the nanosheet microstructure is relatively complete, the transmission electron microscope scanning image shows slight agglomeration. Anions can pin oxygen defects by bonding with atoms around oxygen defects. The electronegativity of N is greater than that of S. In the coupled metal ion Mo-nailed layered MnO 2 structure, N can more effectively regulate the electron cloud distribution, making the electron cloud distribution around oxygen defects and the overall structure of MnO 2 more uniform, with better charge balance, reducing structural damage caused by electron disorder and improving the structural stability of the microstructure. While S is less capable of regulating the electron cloud and maintaining charge balance, it is prone to causing structural stress and reducing the structural stability of the microstructure.

[0068] Figure 3 are the scanning electron microscope images of the composite materials of Comparative Examples 1-5. In Comparative Example 1, the laser parameters were changed and the laser power was reduced to 20%, but the nanosheet microspheres were relatively complete. Compared with the N / Ov-Mo-MnO 2 in Example 1, the morphological change was small. In Comparative Example 2, the laser power was increased to 50%, and the nanosheets on the material surface were damaged and presented as needle-like substances. In Comparative Example 3, the laser power was determined, but the number of laser scanning circles was changed to 6 circles. It was found that the nanosheet structure of the obtained sample was a microsphere structure formed by the agglomeration of nanospheres connected by bead-shaped nanosheets, and nitrides were formed and coated on the surface of the nanospheres. When used as an electrode, it would affect the insertion of zinc ions. In Comparative Example 4, the laser parameters were determined and the proportion of S powder was increased. The surface of the obtained sample was damaged to form a microsphere with agglomerated nanoparticles. In Comparative Example 5, the laser parameters were determined and the proportion of S powder was reduced. Its surface structure was close to that of S / Ov-Mo-MnO 2, but there are still some damages to the structure. In general, it can be seen that the morphological changes of Comparative Example 1 and Comparative Example 5 are relatively small, while certain morphological changes have occurred in Comparative Examples 2-4.

[0069] From Figure 4 in (a) and Figure 4 in (b), it can be seen that XPS is used to test the contents of nitrogen element and oxygen defects in N / Ov-Mo-MnO 2 . As the etching depth increases during the detection, the intensity of the characteristic peaks corresponding to the N element and oxygen defects in the XPS spectrum does not change, indicating that the contents of the N element and oxygen defects are evenly distributed within MnO 2 .

[0070] Figure 4 In (c) is the EPR image of MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 . Compared with MnO 2 , after the Mo atomic pinning layered MnO 2 , the oxygen defect content in Mo-MnO 2 slightly increases; after Ov-Mo-MnO 2 is in the oxygen defect-rich coupled metal ion Mo pinning layered MnO 2 , the oxygen defect content increases significantly; indicating that the laser treatment can effectively increase the defect content in the material. After N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 are in the anion N or S pinning oxygen defect coupled metal ion Mo pinning layered MnO 2 , compared with Ov-Mo-MnO 2 , the defect content decreases significantly, indicating the successful pinning of anions.

[0071] Figure 5 is the XRD pattern of MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 . Compared with MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2The phase of the substance did not change, but the corresponding characteristic peaks shifted, indicating that the lattice spacing changed. After the metal ion Mo pinned the layered MnO 2 , Mo-MnO 2 's XRD pattern showed that the characteristic peaks shifted towards smaller angles, indicating that the layer spacing of MnO 2 increased. After the anion N or S pinned the oxygen vacancies and coupled with the metal ion Mo to pin the layered MnO 2 , the layer spacing of N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 would also increase, which was beneficial to constructing a fast ion transport channel.

[0072] Figure 6 For MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 , the band gap width and the position of the Fermi level. MnO 2 had a relatively wide band gap (1.64 eV). When Mo atoms were used as interlayer pillars, the band gap of Mo-MnO 2 narrowed (0.87 eV). After creating oxygen vacancies by laser irradiation, the band gap width of Ov-Mo-MnO 2 was 0.62 eV. Although the band system became significantly narrower after laser treatment, it still had a relatively large bandwidth. However, after the anion N or S pinned the oxygen vacancies, the band gaps of N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 were almost completely filled, and the bandwidth decreased significantly, being 0.0006 eV (N pinning) and 0.0019 eV (S pinning) respectively, which significantly enhanced the conductivity of the material. In addition, the Fermi level gradually shifted upward, the carrier concentration increased, the conductivity improved, and the electrochemical activity enhanced. This increased the density of energy storage active sites. At the same time, it could enhance the adsorption force on Zn 2+ , optimize its diffusion path within the material, accelerate the electrode reaction kinetics, and improve the storage capacity, charge-discharge efficiency, and rate performance.

[0073] Experimental Example 2: Performance Test

[0074] (1) Respectively, for MnO 2 , Mo-MnO prepared in step (1) of Example 1 2 , Ov-Mo-MnO prepared in step (2) of Example 1 2 , N / Ov-Mo-MnO prepared in Example 1 2, S / Ov-Mo-MnO prepared in Example 2 2 , N-Mo-MnO prepared in Comparative Example 1 2 -20%, N-Mo-MnO prepared in Comparative Example 2 2 -50%, N-Mo-MnO prepared in Comparative Example 3 2 -6, S-Mo-MnO prepared in Comparative Example 4 2 -5 and S-Mo-MnO prepared in Comparative Example 5 2 -15, are mixed with carbon powder and binder (mass ratio 7:2:1), N-methylpyrrolidone is added, and it is ground evenly to obtain a viscous electrode paste. The viscous electrode paste is evenly coated on a substrate titanium foil (0.02 mm), and the loading amount is controlled to be about 1 mg·cm 2 Then it is dried in a vacuum drying oven and cut into circular pieces with a radius of 6 mm using a cutting machine to obtain manganese dioxide electrode sheets.

[0075] (2) Using the above manganese dioxide electrode sheet as the positive electrode, a zinc sheet with a thickness of 0.1 mm as the negative electrode, a glass fiber with a diaphragm model of 1825 - 150, and an electrolyte of 2 mol·L -1 ZnSO 4 +0.1 mol·L -1 MnSO 4 solution, a button battery is assembled with the battery model of CR2025. The battery performance is measured by a Blue Electric battery test system and a CHI electrochemical workstation.

[0076] Figure 7 are the work function values of MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 . After Mo atoms are pinned to the layered MnO 2 , the work function of Mo-MnO 2 decreases. This is because the electron orbit of Mo hybridizes with the electron orbit of the layered MnO 2 , changing the electron state density distribution of the whole system, increasing the electron state density near the Fermi level, making electrons more likely to escape from the material surface, and thus reducing the work function. After introducing oxygen defects, the work function of Ov-Mo-MnO 2 further decreases. The local electric field formed by the charge and electron cloud distortion around the oxygen defects, and the interaction between the electron cloud near the oxygen defects and the electron cloud around Mo strengthen the regulation of electrons, thereby further reducing the work function of the material. Anion N or S pins oxygen defects and couples with metal ion Mo to pin the layered MnO 2After that, N / Ov-Mo-MnO 2 、S / Ov-Mo-MnO 2 The N or S in aggregates near the oxygen defects. There is a difference in electronegativity between N or S and O. This pinning effect changes the electron cloud distribution around the oxygen defects, enhances the binding ability of electrons at the oxygen defects, making the electron cloud more concentrated in the defect region. This change in electron cloud distribution couples with the electron orbitals of metallic Mo between the layers and the electron orbitals of layered MnO 2 to undergo hybridization, forming an additional electric field, thereby changing the electron state density distribution of the entire system, making it easier for electrons to escape from the interior of the material to the surface and reducing the work function of the material. And the electronegativity of N (3.04) is greater than that of S (2.58). When pinning the oxygen defects, N has a stronger ability to attract electrons, and it is easier to distort the electron cloud distribution around the oxygen defects, forming a stronger local electric field. Therefore, N / Ov-Mo-MnO 2 has the lowest work function. For materials with a low work function, electrons are more likely to spill out, making the electrochemical activity of MnO 2 enhanced, and accelerating the redox reaction rate during the Zn 2+ insertion and extraction processes. It can be concluded that N / Ov-Mo-MnO 2 has a high charge / mass transfer efficiency and reaction kinetics process.

[0077] Figure 8 is MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 for the adsorption energy of Zn 2+ and H + . Among them, the pinning of Mo reduces the adsorption energy to a certain extent. The construction of oxygen defects affects the energy of the adsorption sites, making the adsorption energy of Ov-Mo-MnO 2 decrease significantly again. However, after the anion pinning, the adsorption energies of N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 increase (N / Ov-Mo-MnO 2 : -1.82 eV, S / Ov-Mo-MnO 2 : -1.74 eV). The adsorption energy represents the interaction strength between the adsorbate and the substrate. The more negative the adsorption energy, the more stable the adsorption process, and at the same time, the more difficult the desorption. Therefore, the moderate adsorption energy of the composite material with anion N or S pinning oxygen defects and coupling metal ion Mo pinning layered MnO 2 is more conducive to Zn 2+ / H+ Embedding / extraction process

[0078] Figure 9 is MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 The magnitude of the adsorption energy of water. In the aqueous electrolyte system, active water easily attacks oxygen defects, leading to structural collapse. Therefore, the higher the adsorption energy of the material for water, the more unfavorable it is for the stability of the material. From Figure 9 it can be seen that N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 have the smallest adsorption energy for water and the highest stability.

[0079] Figure 10 In (a) of Figure 10 and (b) of 2 are the CV curves and charge-discharge cycling curves of MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO; Figure 10 In (c) of Figure 10 and (d) of 2 are the CV curves and charge-discharge curves of Comparative Examples 1-5. It can be obtained from the CV curves that each curve has two pairs of redox peaks, indicating that the electrochemical process of the material is a dual-ion embedding / extraction process. However, N / Ov-Mo-MnO 2 has the highest peak current, indicating that N / Ov-Mo-MnO 2 has the highest electrode activity and the best electrode reaction kinetics. The information obtained from the discharge curves is the same as that of the CV curves. Each curve has two discharge platforms, indicating that the electrochemical process of the material is a dual-ion embedding / extraction process, and N / Ov-Mo-MnO

[0080] The laser power of Comparative Example 1 is insufficient, and N cannot effectively pin oxygen defects, making it difficult to adjust the electronic structure. The battery capacity is reduced compared to N / Ov-Mo-MnO 2 . The laser power of Comparative Example 2 is too high, damaging MnO 2The surface structure with reduced ion storage sites greatly affects the cycling stability and battery capacity of the material. In Comparative Example 3, the excessive number of scanning cycles easily forms nitrides on the surface, which adhere to the surface of the active material, affecting the insertion of ions and reducing the material capacity. In Comparative Example 4, the excessive doping of S results in the formation of a layer of sulfide on the material surface. During charge and discharge, it is difficult for ions to be inserted, reducing the material capacity. In Comparative Example 5, the amount of S doping is too small, and S cannot effectively pin oxygen defects, failing to play the role of regulating the electronic structure and stabilizing the structure. The battery capacity is reduced compared to S / Ov-Mo-MnO 2 is somewhat reduced.

[0081] Figure 11 is MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 The long-term cycling performance at a current density of 1 Ag -1 is shown. It can be seen from the figure that the composite material with anionic N pinning oxygen defects and coupled metal ion Mo pinning layered MnO 2 has the most cycling times and the highest capacity.

[0082] Figure 12 is MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 The dissolution of Mn during charge and discharge is shown. The Mn 2+ concentration in the figure is the Mn 2+ concentration in the electrolyte after charge and discharge. When the number of cycling times is the same, compared with MnO 2 , after Mo atoms are pinned to layered MnO 2 , the dissolution of Mn 2 in Mo-MnO 2+ is somewhat inhibited. However, the content of Mn 2 in the electrolyte of Ov-Mo-MnO 2+ increases, indicating that excessive oxygen defects are not conducive to the stability of the material. After anionic pinning of oxygen-deficient coupled metal ion Mo pinning layered MnO 2 , the content of Mn 2 in N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2+ in the electrolyte decreases significantly, indicating that anionic N or S pinning oxygen defects and coupled metal ion Mo pinning layered MnO 2The composite material has good stability.

[0083] Figure 13 MnO 2 , Mo-MnO 2 , Ov-Mo-MnO 2 , N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 The images of constant current intermittent titration (GITT) and Mn 2+ Migration energy. Mo-MnO 2 The pinning of Mo atoms in the layered MnO 2 The interlayer spacing of Ov-Mo-MnO increases, the ion diffusion energy decreases, and the ion migration speed increases. 2 In N / Ov-Mo-MnO, the presence of oxygen defects weakens the electrostatic force between the layers during ion diffusion, so the ion diffusion rate is further accelerated and the diffusion energy is reduced. 2 and S / Ov-Mo-MnO 2 In the process, a built-in electric field is formed between the anions and cations, which accelerates the migration of ions again, making N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 The diffusion rate of ions in the medium is faster and the migration energy is lower.

[0084] Figure 14 Schematic diagram of the working principle of the surface site and interlayer structure coupling pinning layered manganese oxide electrode materials in aqueous zinc ion batteries. 2 The interlayer spacing is small, which is not conducive to the Zn 2+ After Mo pins the interlayer structure, the Mo-MnO 2 The interlayer spacing of Zn is enlarged, which is beneficial to 2+ The embedding and extraction of Mo atoms can be carried out, and Mo atoms can serve as interlayer pillars to prevent the layered structure from sliding during charge and discharge, which would lead to structural collapse. After the introduction of oxygen defects by laser, Ov-Mo-MnO 2 The traps in the can adjust the electronic structure and increase the conductivity. At the same time, oxygen defects can increase the ion storage sites and improve the specific capacity of the positive electrode. However, too many oxygen defects have a strong adsorption effect on water molecules in the aqueous solution. Water molecules easily attack oxygen defects, causing Jahn-Taylor distortion, leading to Mn dissolution, affecting the material's cycle stability and specific capacity; after the anion N or S pins the oxygen defect, N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2 The adsorption of water is weakened, the Jahn-Taylor distortion is suppressed, and N / Ov-Mo-MnO 2 and S / Ov-Mo-MnO 2The cyclic stability and specific capacity are improved, and an internal electric field is formed between the anion N or S and Mo, accelerating the diffusion rate of ions in N / Ov-Mo-MnO 2 , S / Ov-Mo-MnO 2 .

[0085] The foregoing are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A layered manganese oxide electrode material coupled with surface sites and interlayer structures, characterized in that: The surface site and interlayer structure coupled pinned layered manganese oxide electrode material is a layered MnO2 coupled with anion pinning oxygen defects and metal ion Mo pinning; The doping amount of Mo is 3 wt %; the doping amount of the anion is 6 wt %; the anion is S 2- or N 3- ; The surface site and interlayer structure coupling pinning layered manganese oxide electrode material is prepared by the following method: (1) dissolving a manganese salt and a molybdenum salt in deionized water in sequence and performing a hydrothermal reaction to obtain a metal ion Mo-pinned layered manganese oxide precursor; (2) Under a protective atmosphere, a plasmon laser is used to irradiate a metal ion Mo-pinned layered manganese oxide precursor to obtain MnO2 pinned by oxygen-rich defect metal ions Mo; the parameters of the plasmon laser are: line spacing of 0.001-0.004 mm, laser scanning speed of 200-500 mm / s, laser power of 30%-40%, and scanning number of 3; (3) In an anion source, a plasmon laser is used to irradiate MnO2 pinned by oxygen-rich defect metal ions Mo to obtain a layered manganese oxide electrode material with surface sites and interlayer structure coupled pinned; the parameters of the plasmon laser are: line spacing of 0.001-0.004 mm, laser scanning speed of 200-500 mm / s, laser power of 30%-40%, and scanning number of 3; the anion source is ammonia or sulfur powder; when the anion source is ammonia, the reaction environment is filled with ammonia; when the anion source is sulfur powder, the reaction environment is filled with protective gas; the mass ratio of MnO2 pinned by oxygen-rich defect metal ions Mo and sulfur powder is 10:1; the mass ratio of MnO2 pinned by oxygen-rich defect metal ions Mo and ammonia is 1:3-6.

2. The surface site and interlayer structure coupled pinned layered manganese oxide electrode material according to claim 1, characterized in that: In step (1), the manganese salt includes KMnO4 and MnSO4·H2O; the molybdenum salt is H 24 Mo7N6O 24 ·4H2O; the KMnO4, MnSO4·H2O and H 24 Mo7N6O 24 The molar ratio of 4H2O is 1:0.15:0.003~0.

01.

3. The surface site and interlayer structure coupled pinned layered manganese oxide electrode material according to claim 1, characterized in that: In step (1), the temperature of the hydrothermal reaction is 120-160° C., and the time of the hydrothermal reaction is 10-16 hours.

4. The surface site and interlayer structure coupled pinned layered manganese oxide electrode material according to claim 1, characterized in that: In step (1), after the hydrothermal reaction is completed, the precipitate is filtered and washed, and the precipitate is vacuum freeze-dried to obtain a metal ion Mo pinned layered manganese oxide precursor.

5. Use of the surface site and interlayer structure coupled pinned layered manganese oxide electrode material according to any one of claims 1 to 4 in improving the specific capacity and cycle stability of aqueous zinc ion batteries.

Images