BiOBr with preferred crystal plane orientation 1-x I x Electrode, BiOBr 1-x I x Preparation methods and applications of electrode materials

Abstract

This invention discloses a BiOBr with preferred crystal plane orientation. 1‑x I x Electrode, BiOBr 1‑x I x Preparation method and application of electrode materials, the BiOBr 1‑x I x The preparation method of the electrode material includes: Step 1: Dissolving Bi(NO3)3·5H2O or BiCl3 powder in acetic acid, and then adding ethylene glycol; Step 2: Adding the prepared solution dropwise to an aqueous solution containing KBr and KI, and stirring to form a suspension; Step 3: Transferring the suspension to a reaction vessel and keeping it at a constant temperature, then cooling it to room temperature, washing it three times with deionized water, and after each washing, using a centrifuge to separate the mixture into layers and removing the supernatant, finally placing the precipitate in a vacuum drying oven for vacuum drying, and then cooling it to room temperature to obtain BiOBr. 1‑x I x Powder. The electrode material prepared by this invention with preferred crystal orientation avoids the structural damage caused by ion insertion and extraction processes. At the same time, by adjusting the band structure of the electrode material, the charge transfer kinetics are promoted, thereby improving the electrode capacity and enhancing the cycle performance and rate performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of energy electrode materials, and more particularly to a BiOBr with preferred crystal plane orientation. 1-x I x Electrode, BiOBr 1-x I x Preparation methods and applications of electrode materials. Background Technology

[0002] Due to the scarcity of fossil fuel resources, the utilization of renewable energy has attracted increasing attention from researchers. Various types of stationary energy storage systems have begun to flourish, among which rechargeable battery technology has become a major energy storage solution due to its excellent portability and high energy conversion efficiency.

[0003] Organic lithium-ion batteries, among rechargeable battery technologies, boast extremely high energy and power densities, leading to their increasingly widespread application. However, the price of scarce lithium resources has surged due to growing market demand, and lithium-ion batteries also exhibit relatively lower safety and environmental friendliness. In 1994, Dahn et al. first proposed rechargeable lithium-ion batteries based on aqueous electrolytes. Since then, aqueous rechargeable non-lithium (e.g., Na+) batteries have been developed. + K + Zn 2+ Mg 2+ Al 3+ Batteries (etc.) have also received attention.

[0004] Organic secondary ion batteries have the following advantages: a large potential window, providing a larger theoretical capacity, high gravimetric and volumetric energy density, excellent rate performance, and good cycle stability.

[0005] Aqueous secondary ion batteries have other advantages, such as high safety, non-flammable electrolyte, low raw material cost, small size of hydrated ions in aqueous solvents, and fast ion diffusion rate.

[0006] As the most ideal rechargeable ion batteries (such as lithium, sodium, and potassium), lithium-ion batteries, which are the most widely used, face significantly increased manufacturing costs due to the limited availability of lithium resources, which may limit their large-scale application in the future. Simultaneously, the slow ion insertion / extraction process in the energy storage electrodes during charge-discharge cycles makes them prone to dendrite formation, leading to a substantial loss of active ions and directly impacting battery capacity. Even potassium-ion and sodium-ion batteries, which have a lower cost advantage due to abundant reserves, face practical problems limiting their large-scale application. For example, the larger radius of potassium and sodium ions makes them more prone to damaging the electrode material structure during insertion and extraction, ultimately resulting in poor cycle stability and low high-current charge-discharge performance.

[0007] The technical problem to be solved by the embodiments of the present invention is to provide a BiOBr with preferred crystal plane orientation. 1- x I x Electrode, BiOBr 1-x I x The preparation method and application of electrode materials are studied to avoid damage to the electrode structure due to ion insertion and extraction during cycling, thereby improving the capacity of bismuth-based ion batteries and enhancing their cycle performance and rate performance.

[0008] To address the aforementioned technical problems, embodiments of the present invention propose a BiOBr with preferred crystal plane orientation. 1- x I x Methods for preparing electrode materials include:

[0009] Step 1: Dissolve Bi(NO3)3·5H2O or BiCl3 powder in acetic acid, then add ethylene glycol to completely dissolve the powder to obtain a solution;

[0010] Step 2: Then add the prepared solution dropwise to the solution containing Br. － and I － In an aqueous solution, and stirred to form a suspension;

[0011] Step 3: Transfer the suspension to a reaction vessel and maintain it at the preset temperature for the preset time. After cooling to room temperature, wash three times with deionized water. After each wash, use a centrifuge to separate the mixture into layers and remove the supernatant. Finally, place the precipitate in a vacuum drying oven for vacuum drying and then cool to room temperature to obtain BiOBr. 1-x I x Powder, where 1 ≥ x ≥ 0.

[0012] Preferably, x = 0.13.

[0013] Preferably, the molar ratio of Bi(NO3)3·5H2O, KBr and KI is 400:333:67.

[0014] Preferably, the volume ratio of acetic acid, ethylene glycol, and aqueous solution is 7.5:1:25.

[0015] Preferably, in step 3, the precipitate is placed in a vacuum drying oven and vacuum dried at 80 °C for 10 h.

[0016] Preferably, the preset temperature is 120 ℃ and the preset time is 12 h.

[0017] Preferably, in step 2, an electromagnetic stirrer is used to stir for 30 minutes.

[0018] Furthermore, embodiments of the present invention also provide the above-described BiOBr with preferred crystal orientation. 1-x I x BiOBr prepared by electrode material preparation method 1-x I x Electrode materials are used in batteries.

[0019] Accordingly, embodiments of the present invention also provide a BiOBr with preferred crystal plane orientation. 1-x I x Electrode preparation methods include:

[0020] Step (1): Cut the flexible carbon cloth to the preset size to obtain a flexible carbon cloth sheet. Use acetone to ultrasonically clean the flexible carbon cloth sheet, then use ethanol to ultrasonically clean the flexible carbon cloth sheet, and then vacuum dry the flexible carbon cloth sheet. Cool to room temperature to obtain a clean and dried flexible carbon cloth sheet.

[0021] Step (2): The BiOBr method described above will be used. 1-x I x BiOBr prepared by electrode material preparation method 1-x I x The powder, conductive carbon black, and Nafion solution were mixed in a mass ratio of 8:1:1, and then ethanol was added as a diluent. The mixture was stirred with an electromagnetic stirrer to obtain a uniform slurry.

[0022] Step (3): The mixed slurry is uniformly coated unidirectionally onto a clean and dried flexible carbon cloth sheet, and then vacuum dried to obtain BiOBr. 1-x I x electrode.

[0023] Furthermore, in step (2), each gram of BiOBr 1-x I x Add 16-20 ml of anhydrous ethanol to the powder as a diluent.

[0024] The beneficial effects of this invention are as follows: First, the electrode material prepared by this invention is a layered, self-assembled nanostructure. The introduction of I element in the form of a solid solution can enhance the preferred crystal orientation and maximize the widening of ion diffusion channels, which can further improve bulk utilization. Layered BiOBr 1-x I x Preferred orientations of crystal planes in a structure exhibit different lattice arrangements, surface energies, and internal electronic properties, inducing different electrochemical effects in ion adsorption and storage. Taking OH... − For example, the corresponding adsorption energy is related to OH. − and BiOBr 1-x I xIt is related to the interaction between the matrices. A higher adsorption energy indicates a higher probability of interaction. For example... Figure 1 Theoretical calculations show that OH − BiOBr tends to spontaneously aggregate in BiOBr with a preferred orientation of the (102) crystal plane. 1-x I x The adsorption energy at the outer surface of the crystal (diffusion depth > 0 Å) is approximately 2.3 eV. Furthermore, OH... − It can diffuse into the lower layers where the depth remains < 2 Å, exhibiting similar characteristics to BiOBr. 1-x I x The matrix exhibits relatively weak interactions (adsorption energy is approximately 1.6 eV). When OH... − When diffusing into deeper matrices (diffusion depth > 2 Å), relatively lower adsorption energies (smaller absolute values) are observed, demonstrating the difficulty of deep diffusion. Correspondingly, OH... − This allows for effective penetration of BiOBr with a preferred orientation of the (110) crystal plane. 1-x I x Crystals achieve diffusion depths greater than 8 Å. When the diffusion depth in the (110) preferred-oriented crystal is 6 Å, the corresponding adsorption energy is -1.85 eV, which is even greater than the adsorption energy on the (sub)surface of the (102) preferred-oriented crystal. This indicates that the (110) preferred-oriented crystal can provide a wider and more efficient range of ion storage sites and ion diffusion paths than the (102) preferred-oriented crystal. Therefore, the (110) preferred orientation of crystals in BiOBr-based electrodes can further promote the full utilization of energy storage sites in electrode materials. II. The negative shift of electronic states can be promoted through solid solution I, reducing the band gap and thus further improving the redox reaction activity. Figure 2 , 3 BiOBr can be read 1-x I x The maximum value of the valence band and the band gap width, combined with the formula E g = E VBM - E CBM You can then draw the material BiOBr. 1-x I x The electronic band structure diagram, such as Figure 4 As shown. Through first-principles calculations, we further investigated the effect of solid solution I on electron orbital distribution and occupancy. The electronic band structures of BiOBr and BiOBrI are shown below. Figure 5 , 6As shown, in the electronic band structure of BiOBrI, CBM is observed located at the Z point, while VBM is located at the FZ junction, confirming that BiOBrI is an indirect semiconductor. The band gap of BiOBr gradually decreases with the introduction of solid solution I. Furthermore, the presence of I enhances the hybridization between individual atomic orbitals in BiOBr, leading to a stronger electronic band structure. The trend of the calculated results is consistent with... Figure 4 The electronic band structure in them is very consistent. This can further explain BiOBr. 1-x I x Its excellent performance. Figure 7 , 8 The total density of states (TDOS) and partial density of states (PDOS) of BiOBr and BiOBrI crystals were depicted, respectively. With the introduction of solid solution I, a significant overall negative shift appears in the band structure. Simultaneously, the highest valence band broadens, and the band gap narrows. By shrinking the BiOBr... 1-x I x The reduced band gap effectively lowers the energy required for electron transitions from the valence band to the conduction band. This effect promotes electron transitions and enhances the material's conductivity under an electric field. Therefore, the reduced band gap leads to more electrons transitioning from the valence band to the conduction band, increasing the concentration of free electrons. This enhanced carrier concentration significantly affects conductivity and redox reactivity. In summary, the electrode material prepared by this invention avoids the damage to the electrode material structure caused by the insertion and extraction processes of stored ions, improves the capacity of bismuth-based ion batteries, and enhances the battery's cycle performance and rate performance. Attached Figure Description

[0025] Figure 1 This invention includes BiOBr crystal preferred orientation at different diffusion depths in Examples 1, 2, and 3. 1-x I x (X takes values ​​of 0, 0.13 and 1 respectively) adsorption energy of ions.

[0026] Figure 2 This invention includes the BiOBr of Embodiments 1, 2, and 3. 1-x I x UPS spectra (X values ​​are 0, 0.13 and 1 respectively).

[0027] Figure 3 This invention includes the BiOBr of Embodiments 1, 2, and 3. 1-x I x (X takes values ​​of 0, 0.13, and 1 respectively) αhv ) 1 / 2 right hv The curve graph.

[0028] Figure 4This invention includes the BiOBr of Embodiments 1, 2, and 3. 1-x I x Electronic band structure diagram (X takes values ​​of 0, 0.13 and 1 respectively).

[0029] Figure 5 Here are the following diagrams: a) band structure diagram; b) band gap diagram of BiOBr according to Embodiment 1 of this invention.

[0030] Figure 6 Here are the a-band structure diagram and b-band gap diagram of BiOBrI, which includes Embodiment 2 of the present invention.

[0031] Figure 7 This invention includes the total density of states and partial density of states diagram of BiOBr from Embodiment 1.

[0032] Figure 8 This invention includes the total density of states and partial density of states diagrams of BiOBrI from Embodiment 2.

[0033] Figure 9 This is the XRD pattern of the BiOBr powder from Example 1 of the present invention.

[0034] Figure 10 This is a constant current charge-discharge curve of the BiOBr electrode in Embodiment 1 of the present invention.

[0035] Figure 11 This is a schematic diagram of the cycling stability of the BiOBr electrode in Embodiment 1 of the present invention.

[0036] Figure 12 This is a charge / discharge rate performance diagram of the BiOBr electrode in Embodiment 1 of the present invention.

[0037] Figure 13 This is BiOBr of Embodiment 2 of the present invention. 0.87 I 0.13 XRD pattern of the powder.

[0038] Figure 14 This invention includes the BiOBr of Embodiments 1, 2, and 3. 1-x I x (X takes values ​​of 0, 0.13 and 1 respectively) Intensity ratio diagram of crystal plane peaks.

[0039] Figure 15 This is BiOBr of Embodiment 2 of the present invention. 0.87 I 0.13 Constant current charge-discharge curves of the electrodes.

[0040] Figure 16 This is BiOBr of Embodiment 2 of the present invention. 0.87 I 0.13 Schematic diagram of the cyclic stability of the electrode.

[0041] Figure 17 This is BiOBr of Embodiment 2 of the present invention. 0.87 I 0.13 Electrode charge / discharge rate performance diagram.

[0042] Figure 18 This is the XRD pattern of the BiOI powder from Example 3 of the present invention.

[0043] Figure 19 This is a constant current charge-discharge curve of the BiOI electrode in Embodiment 3 of the present invention.

[0044] Figure 20 This is a schematic diagram of the cycling stability of the BiOI electrode in Embodiment 3 of the present invention.

[0045] Figure 21 This is a charge / discharge rate performance diagram of the BiOI electrode in Embodiment 3 of the present invention. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0047] This invention employs a one-step hydrothermal method to prepare BiOBr. 0.004 mol of Bi(NO3)3·5H2O powder is dissolved in 7.5 ml of acetic acid, and 1 ml of ethylene glycol is added as a co-solvent. The solution is sonicated for 2 hours to completely dissolve the powder. The resulting solution is then added dropwise to 25 ml of an aqueous solution containing 0.004 mol KBr, and stirred for 30 min using a magnetic stirrer to form a milky white suspension. The suspension is then transferred to a reaction vessel and kept at 120 °C for 12 h. After cooling to room temperature, the mixture is washed three times with deionized water. After each wash, the mixture is separated into layers using a centrifuge, and the supernatant is removed. Finally, the precipitate is placed in a vacuum drying oven and dried at 80 °C for 10 h. After cooling to room temperature, the BiOBr powder is collected.

[0048] The XRD pattern of BiOBr powder is shown below. Figure 9 As shown.

[0049] Cut the flexible carbon fiber cloth into 1*1.5 cm pieces. 2Small pieces of carbon cloth were ultrasonically cleaned with acetone for 15 min, followed by ultrasonic cleaning with ethanol for 15 min. They were then vacuum-dried at 80 °C for 4 h and cooled to room temperature before being set aside. The prepared BiOBr powder was mixed with conductive carbon black and Nafion solution in an 8:1:1 mass ratio, with an appropriate amount of ethanol added as a diluent. The mixture was stirred with a magnetic stirrer for 2 h to obtain a homogeneous slurry. This slurry was then uniformly coated unidirectionally onto the previously cleaned and dried carbon cloth pieces and vacuum-dried at 80 °C for 4 h to obtain BiOBr electrodes with 1-2 mg of active material per piece.

[0050] The prepared BiOBr electrode was used as the working electrode, and a three-electrode system consisting of a platinum sheet electrode and a mercury oxide electrode was used for subsequent performance characterization. First, cyclic voltammetry (CV) was performed for 20 cycles in the range of -0.9V to 0V at a scan rate of 25mV / s using an electrochemical workstation to activate the electrode. Then, the electrochemical performance of the three-electrode system was characterized using a LAND battery system.

[0051] The constant current charge-discharge curve (CP) of the BiOBr electrode is as follows: Figure 10 As shown, when the charging and discharging current density is 8 Ag -1 At that time, the discharge capacity of the electrode sheet was 31.12 mAh g. -1 When the charging and discharging current density is 4 Ag -1 At that time, the discharge capacity of the electrode sheet was 45.56 mAh g. -1 When the charging and discharging current density is 2 Ag -1 At that time, the discharge capacity of the electrode sheet was 77.22 mAh g. -1 When the charging and discharging current density is 1 Ag -1 At that time, the discharge capacity of the electrode plate was 125.83 mAh g. -1 .

[0052] The cycling stability of the BiOBr electrode is as follows: Figure 11 As shown, the discharge capacity of the first BiOBr electrode is 89.2 mAh g. -1 The discharge capacity of the BiOBr electrode in the 50th cycle was 76.1 mAh g. -1 The capacity retention rate was 85.31%; the discharge capacity of the BiOBr electrode after 100 cycles was 66.4 mAh g. -1 The capacity retention rate was 74.44%.

[0053] The fast-charging performance of the BiOBr electrode is reflected in the electrode's charge / discharge rate performance graph, such as... Figure 12 As shown, with 10 cycles as one period, the change in current density during constant current charging and discharging is as follows: 1 Ag -1 → 2Ag-1 → 4Ag -1 → 16Ag -1 →1 Ag -1 In Ag 1, 2, 4, and 16 -1 At the specified current densities, the discharge capacities of the BiOBr electrode were 81.2, 74.4, 44.6, and 25.9 mAh g, respectively. -1 As can be clearly seen from the figure, the discharge capacity loss of the BiOBr electrode is not significant at high current densities. However, when the current density drops back to 1 Ag... -1 At that time, the average discharge capacity of the BiOBr electrode can even recover to 89.7 mAh g. -1 The capacity retention rate was 110.47%. Example 2

[0054] This invention employs a one-step hydrothermal method to prepare BiOBr. 0.87 I 0.13 0.004 mol of Bi(NO3)3·5H2O powder was dissolved in 7.5 ml of acetic acid, and 1 ml of ethylene glycol was added as a co-solvent. The solution was sonicated for 2 hours to completely dissolve the powder. The resulting solution was then added dropwise to 25 ml of an aqueous solution containing 0.00333 mol KBr and 0.00067 mol KI, and stirred with a magnetic stirrer for 30 min to form a dark brown suspension. The suspension was then transferred to a reaction vessel and kept at 120 °C for 12 h. After cooling to room temperature, the mixture was washed three times with deionized water. After each wash, the mixture was separated into layers using a centrifuge, and the supernatant was removed. Finally, the precipitate was placed in a vacuum drying oven and dried at 80 °C for 10 h. After cooling to room temperature, BiOBr was collected. 0.87 I 0.13 powder.

[0055] BiOBr 0.87 I 0.13 The XRD pattern of the powder is shown below. Figure 13 As shown in the figure, the prepared BiOBr 0.87 I 0.13 The active material is preferentially oriented on the (110) crystal plane; by Figure 14 From the ratio of the intensity of the peak on the (110) crystal plane to the intensity of the peak on the (102) crystal plane, it can be seen that BiOBr 0.87 I 0.13 The (110) crystal plane has the largest preferred orientation. The introduced I element can adjust the position of the electronic band structure based on BiOBr, and this fine-tuning reduces the band gap. Overall, BiOBr 0.87 I 0.13The active material exhibits better charge transfer kinetics and better electrochemical reactivity.

[0056] Cut the flexible carbon fiber cloth into 1*1.5 cm pieces. 2 The small pieces were ultrasonically cleaned with acetone for 15 min, followed by ultrasonic cleaning with ethanol for 15 min, and then vacuum dried at 80 °C for 4 h. After cooling to room temperature, they were set aside for later use. The prepared BiOBr 0.87 I 0.13 The powder, conductive carbon black, and Nafion solution were mixed in an 8:1:1 mass ratio, with an appropriate amount of ethanol added as a diluent. The mixture was stirred using a magnetic stirrer for 2 hours to obtain a homogeneous slurry. This slurry was then uniformly coated unidirectionally onto previously cleaned and dried carbon cloth sheets and vacuum-dried at 80°C for 4 hours to obtain 1-2 mg of BiOBr active material per sheet. 0.87 I 0.13 electrode.

[0057] BiOBr produced 0.87 I 0.13 The electrode was used as the working electrode, and a three-electrode system consisting of a platinum sheet electrode and a mercury oxide electrode was formed for subsequent performance characterization. First, cyclic voltammetry (CV) was performed for 20 cycles at a scan rate of 25 mV / s within the -0.9 V to 0 V range using an electrochemical workstation to activate the electrode. Then, the electrochemical performance of this three-electrode system was characterized using a LAND battery system. (BiOBr) 0.87 I 0.13 The constant current charge-discharge curve (CP) of the electrode is as follows: Figure 15 As shown, when the charging and discharging current density is 8Ag -1 At that time, the discharge capacity of the electrode sheet was 44.41 mAh g. -1 When the charging and discharging current density is 4 Ag -1 At that time, the discharge capacity of the electrode sheet was 98.64 mAh g. -1 When the charging and discharging current density is 2 Ag -1 At that time, the discharge capacity of the electrode sheet was 113.58 mAh g. -1 When the charging and discharging current density is 1 Ag -1 At that time, the discharge capacity of the electrode sheet was 187.88 mAh g. -1 .

[0058] BiOBr 0.87 I 0.13 The cyclic stability of the electrode is as follows Figure 16 As shown, the first circumference of BiOBr 0.87 I 0.13 The discharge capacity of the electrode is 176.9 mAh g. -1 ; 50th lap BiOBr0.87 I 0.13 The discharge capacity of the electrode is 184.6 mAh g. -1 The capacity retention rate was 104.35%; BiOBr at the 100th cycle 0.87 I 0.13 The discharge capacity of the electrode is 136.5 mAh g. -1 The capacity retention rate was 77.16%.

[0059] BiOBr 0.87 I 0.13 The fast-charging performance of the electrode is reflected in the electrode's charge / discharge rate performance diagram, such as... Figure 17 As shown, with 10 cycles as one period, the change in current density during constant current charging and discharging is as follows: 1 Ag -1 → 2Ag -1 → 4Ag -1 →16Ag -1 → 1 Ag -1 In Ag 1, 2, 4, and 16 -1 At current density, BiOBr 0.87 I 0.13 The discharge capacities of the electrodes were 159.61, 159.91, 153.09, and 94.63 mAh g, respectively. -1 From the diagram, we can clearly see that BiOBr 0.87 I 0.13 The electrode does not exhibit significant discharge capacity loss at high current densities, only showing a decrease at ultra-high currents (16Ag). -1 Only when the current density drops back to 1 Ag will the discharge capacity decrease significantly. -1 At that time, BiOBr 0.87 I 0.13 The average discharge capacity of the electrode can even be restored to 159.22 mAh g. -1 The capacity retention rate reached an astonishing 99.75%.

[0060] According to the BiOBr of the present invention 1-x I x BiOBr prepared by electrode material preparation method 1-x I x Electrode materials are used in batteries, with preferred materials being alkali metal ion storage, alkaline earth metal ion storage, and alkaline ion storage batteries. Example 3

[0061] This invention employs a one-step hydrothermal method to prepare BiOI. 0.004 mol of Bi(NO3)3·5H2O powder is dissolved in 7.5 ml of acetic acid, and 1 ml of ethylene glycol is added as a co-solvent. The solution is sonicated for 2 hours to completely dissolve the powder. The resulting solution is then added dropwise to 25 ml of an aqueous solution containing 0.004 mol KI, and stirred for 30 min using a magnetic stirrer to form a dark brown suspension. The suspension is then transferred to a reaction vessel and kept at 120 °C for 12 h. After cooling to room temperature, the mixture is washed three times with deionized water. After each wash, the mixture is separated into layers using a centrifuge, and the supernatant is removed. Finally, the precipitate is placed in a vacuum drying oven and dried at 80 °C for 10 h. After cooling to room temperature, the BiOI powder is collected.

[0062] The XRD pattern of BiOI powder is shown below. Figure 18 As shown.

[0063] Cut the flexible carbon fiber cloth into 1*1.5 cm pieces. 2 The small pieces were ultrasonically cleaned with acetone for 15 min, followed by ultrasonic cleaning with ethanol for 15 min, and then vacuum dried at 80 °C for 4 h. After cooling to room temperature, they were set aside for later use. The prepared BiOBr 0.87 I 0.13 The powder, conductive carbon black, and Nafion solution were mixed in an 8:1:1 mass ratio, with an appropriate amount of ethanol added as a diluent. The mixture was stirred for 2 hours using a magnetic stirrer to obtain a homogeneous slurry. The slurry was then uniformly coated unidirectionally onto previously cleaned and dried carbon cloth sheets and vacuum dried at 80°C for 4 hours to obtain BiOI electrodes with 1-2 mg of active material per sheet.

[0064] The prepared BiOI electrode was used as the working electrode, and a three-electrode system consisting of a platinum sheet electrode and a mercury oxide electrode was used for subsequent performance characterization. First, cyclic voltammetry (CV) was performed for 20 cycles at a scan rate of 25 mV / s within the -0.9 V to 0 V range using an electrochemical workstation to activate the electrode. Then, the electrochemical performance of the three-electrode system was characterized using a LAND battery system. The constant current charge-discharge (CP) curve of the BiOI electrode is shown below. Figure 19 As shown, when the charging and discharging current density is 8 Ag -1 At that time, the discharge capacity of the electrode sheet was 51.11 mAh g. -1 When the charging and discharging current density is 4 Ag -1 At that time, the discharge capacity of the electrode sheet was 51.21 mAh g. -1 When the charging and discharging current density is 2 Ag -1 At that time, the discharge capacity of the electrode sheet was 52.22 mAh g. -1 When the charging and discharging current density is 1 Ag-1 At that time, the discharge capacity of the electrode sheet was 81.66 mAh g. -1 .

[0065] The cycling stability of the BiOI electrode is as follows: Figure 20 As shown, the discharge capacity of the first BiOI electrode is 80.5 mAh g. -1 The discharge capacity of the BiOI electrode in the 50th cycle was 77.1 mAh g. -1 The capacity retention rate was 95.78%; the discharge capacity of the BiOI electrode after 100 cycles was 65.6 mAh g. -1 The capacity retention rate was 81.49%.

[0066] The fast-charging performance of the BiOI electrode is reflected in the electrode's charge-discharge rate performance graph, such as... Figure 21 As shown, with 10 cycles as one period, the change in current density during constant current charging and discharging is as follows: 1 Ag -1 → 2Ag -1 → 4Ag -1 → 16Ag -1 →1 Ag -1 In Ag 1, 2, 4, and 16 -1 At the specified current densities, the discharge capacities of the BiOI electrode were 40.83, 14.91, 14.39, and 14.33 mAh g⁻¹, respectively. -1 As can be clearly seen from the figure, the discharge capacity loss of the BiOI electrode is not significant at high current densities, but only at ultra-high currents (16Ag). -1 Only when the current density drops back to 1 Ag will the discharge capacity decrease significantly. -1 At this time, the average discharge capacity of the BiOI electrode can even recover to 42.32 mAh g⁻¹. -1 The capacity retention rate reached 103.65%.

[0067] According to the BiOBr of the present invention 1-x I x BiOBr prepared by electrode material preparation method 1-x I x Electrode materials are used in batteries, with preferred materials being alkali metal ion storage, alkaline earth metal ion storage, and alkaline ion storage batteries.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A BiOBr with preferred crystal plane orientation 1-x I x The method for preparing electrode materials is characterized by, include: Step 1: Dissolve Bi(NO3)3·5H2O or BiCl3 powder in acetic acid, then add ethylene glycol to completely dissolve the powder to obtain a solution; Step 2: Then add the prepared solution dropwise to the solution containing Br. － and I － In an aqueous solution, and stirred to form a suspension; Step 3: Transfer the suspension to a reaction vessel and maintain it at the preset temperature for the preset time. After cooling to room temperature, wash three times with deionized water. After each wash, use a centrifuge to separate the mixture into layers and remove the supernatant. Finally, place the precipitate in a vacuum drying oven for vacuum drying and then cool to room temperature to obtain BiOBr. 1-x I x Powder, where x = 0.

13.

2. The BiOBr with preferred crystal plane orientation as described in claim 1 1-x I x The method for preparing electrode materials is characterized by, The molar ratio of Bi(NO3)3·5H2O, KBr and KI is 400:333:

67.

3. The BiOBr with preferred crystal plane orientation as described in claim 1 1-x I x The method for preparing electrode materials is characterized by, The volume ratio of acetic acid, ethylene glycol, and aqueous solution is 7.5:1:

25.

4. The BiOBr with preferred crystal plane orientation as described in claim 1 1-x I x The method for preparing electrode materials is characterized by, In step 3, the precipitate is placed in a vacuum drying oven and dried under vacuum at 80 °C for 10 h.

5. The BiOBr with preferred crystal plane orientation as described in claim 1 1-x I x The method for preparing electrode materials is characterized by, The preset temperature is 120 ℃ and the preset time is 12 h.

6. The BiOBr with preferred crystal plane orientation as described in claim 1 1-x I x The method for preparing electrode materials is characterized by, In step 2, stir using an electromagnetic stirrer for 30 minutes.

7. A BiOBr having a preferred crystal plane orientation as described in any one of claims 1 to 6 1-x I x BiOBr prepared by electrode material preparation method 1-x I x Electrode materials are used in batteries.

8. A BiOBr with preferred crystal plane orientation 1-x I x The method for preparing the electrode is characterized in that, include: Step (1): Cut the flexible carbon cloth to the preset size to obtain a flexible carbon cloth sheet. Use acetone to ultrasonically clean the flexible carbon cloth sheet, then use ethanol to ultrasonically clean the flexible carbon cloth sheet, and then vacuum dry the flexible carbon cloth sheet. Cool to room temperature to obtain a clean and dried flexible carbon cloth sheet. Step (2): Using BiOBr with preferred crystal orientation as described in any one of claims 1 to 6 1-x I x BiOBr prepared by electrode material preparation method 1-x I x The powder, conductive carbon black, and Nafion solution were mixed in a mass ratio of 8:1:1, and then ethanol was added as a diluent. The mixture was stirred with an electromagnetic stirrer to obtain a uniform slurry. Step (3): The mixed slurry is uniformly coated unidirectionally onto a clean and dried flexible carbon cloth sheet, and then vacuum dried to obtain BiOBr. 1-x I x electrode.

9. The BiOBr with preferred crystal plane orientation as described in claim 8 1-x I x The method for preparing the electrode is characterized in that, In step (2), each gram of BiOBr 1-x I x Add 16-20 ml of anhydrous ethanol to the powder as a diluent.

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