Anode active material and preparation method thereof, composite photoelectrode and super capacitor battery

Abstract

The invention discloses an anode active material and a preparation method thereof, a composite photoelectrode and a super capacitor battery, and relates to the technical field of electrochemical energy storage, the anode active material comprises oxygen-deficient bismuth vanadate and lanthanum chloride loaded on the oxygen-deficient bismuth vanadate, and the anode active material has pores. According to the invention, bismuth vanadate in the anode active material has oxygen defects, so that the conductivity of the bismuth vanadate electrode is improved, and the separation of electrons and holes in a bismuth vanadate bulk phase is promoted; lanthanum chloride in the anode active material promotes the injection efficiency of carriers on the surface of the bismuth vanadate electrode, the valence band structure of bismuth vanadate is changed, and the conductivity is greatly improved; in addition, the anode active material has pores, so that enough mechanical strain space is provided in the charging and discharging process, the volume expansion of bismuth is relieved, and the stability of the electrode is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to an anode active material and a preparation method thereof, a composite photoelectrode and a supercapacitor battery. Background Art

[0002] In the field of electrochemical energy storage, bismuth vanadate is considered an excellent carrier due to its non-toxicity, good compatibility, and favorable formation of reactive oxygen species, and has attracted considerable attention in the field of electrode materials. Furthermore, as an n-type semiconductor, bismuth vanadate, whose components are abundant on Earth, has been used as a photocatalytic oxidation material and is now increasingly being applied as an anode material in electrochemical water splitting.

[0003] However, as a semiconductor material, bismuth vanadate has a band gap of only 2.2 eV. While it exhibits a strong response to electrons, its electrochemical properties are unstable due to its high carrier-hole binding rate and slow interfacial hole transfer. Consequently, pure bismuth vanadate exhibits poor stability and is prone to deactivation. Furthermore, its electrical conductivity is poor.

[0004] Currently, methods for modifying bismuth vanadate materials include preparing single atoms, constructing metal-organic framework (MOF) materials, constructing core-shell structures, or utilizing the Mott-Schottky effect between metals and carriers to increase conductivity, but these methods will lead to a decrease in the stability of bismuth vanadate materials. Summary of the Invention

[0005] The main purpose of the present invention is to provide an anode active material and a preparation method thereof, a composite photoelectrode and a supercapacitor battery, aiming to solve the problems of poor conductivity and stability of bismuth vanadate materials in the prior art.

[0006] To achieve the above objectives, the present invention provides an anode active material, comprising oxygen-deficient bismuth vanadate and lanthanum chloride supported on the oxygen-deficient bismuth vanadate, wherein the anode active material has pores.

[0007] In one embodiment, the particle size of the anode active material is 4 to 6 μm;

[0008] The molar ratio of the oxygen-deficient bismuth vanadate to lanthanum chloride is 15 to 16;

[0009] The porosity of the anode active material is 20-30%;

[0010] The specific surface area of ​​the anode active material is 1.0 to 1.2 m 2 / g;

[0011] The anode active material has a honeycomb structure.

[0012] The present invention also provides a method for preparing an anode active material, comprising the following steps:

[0013] S10, mixing a bismuth source, a vanadium source, lanthanum chloride and ethylene glycol to obtain a mixed solution;

[0014] S20, adjusting the pH of the mixed solution to less than 7, and performing heat treatment until a precipitate is generated to obtain the anode active material.

[0015] In one embodiment, in step S10:

[0016] The bismuth source includes bismuth nitrate;

[0017] The vanadium source includes ammonium vanadate;

[0018] The molar ratio of bismuth ions in the bismuth source to vanadium ions in the vanadium source is 1:(0.8-1.2);

[0019] The molar ratio of lanthanum ions in the lanthanum chloride to bismuth ions in the bismuth source is (0.326-0.408):5;

[0020] The mixing time is 20 to 40 minutes.

[0021] In one embodiment, in step S20:

[0022] The pH is 1 to 3;

[0023] The temperature of the heat treatment is 110-140°C;

[0024] The heat treatment time is 3 to 5 hours.

[0025] In one embodiment, step S20 includes:

[0026] The pH of the mixed solution is adjusted to less than 7, and heat treatment is performed until a precipitate is generated. The solid and liquid are separated, and the solid is taken and vacuum dried at 70-90° C. to obtain the anode active material.

[0027] The present invention also provides a composite photoelectrode, which includes a substrate, and an anode active material and a conductive agent loaded on the surface of the substrate. The anode active material includes the anode active material as described above or the anode active material prepared by the preparation method of the anode active material as described above.

[0028] In one embodiment, the composite photoelectrode further comprises a binder for bonding the substrate and the anode active material:

[0029] The substrate comprises copper foil;

[0030] The conductive agent includes conductive carbon black or carbon fiber;

[0031] The binder includes polyvinylidene fluoride or polyvinyl pyrrolidone.

[0032] The present invention also provides a supercapacitor battery, which includes a metal lithium sheet, a diaphragm, an electrolyte, and the anode active material as described above or the anode active material prepared by the method for preparing the anode active material as described above or the composite photoelectrode as described above.

[0033] In one embodiment, the specific capacity of the supercapacitor battery is 1059.0 to 1062.0 mAh g -1 .

[0034] In the technical solution of the present invention, the bismuth vanadate in the anode active material has oxygen defects, which improves the conductivity of the bismuth vanadate electrode and promotes the separation of electrons and holes in the bismuth vanadate bulk phase; the lanthanum chloride in the anode active material promotes the injection efficiency of carriers on the surface of the bismuth vanadate electrode, changes the valence band structure of bismuth vanadate, and greatly improves the conductivity; in addition, the anode active material has pores, which provide sufficient mechanical strain space during the charge and discharge process, alleviate the volume expansion of bismuth, and improve the stability of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0036] Figure 1 This is a scanning electron microscope image of the anode active material BVO-LC in Example 1 provided by the present invention;

[0037] Figure 2 This is a scanning electron microscope image of bismuth vanadate BVO in Comparative Example 1 provided by the present invention;

[0038] Figure 3 X-ray diffraction (XRD) patterns of the anode active materials BVO-LC, BVO-LC2, BVO-LC3, BVO-LC4, and BVO-LC5 in Examples 1 to 5 provided by the present invention;

[0039] Figure 4 This is a bet test diagram of the anode active material BVO-LC in Example 1 provided by the present invention;

[0040] Figure 5 This is a bet test graph of the anode active material BVO in Comparative Example 1 provided by the present invention;

[0041] Figure 6 The cyclic voltammetry (CV) curves of the supercapacitor batteries corresponding to Example 1 and Comparative Example 1 provided by the present invention are shown;

[0042] Figure 7 This is a constant current charge / discharge (GCD) curve of the supercapacitor battery corresponding to Example 1 and Comparative Example 1 provided by the present invention;

[0043] Figure 8 This is a rate performance diagram of the supercapacitor battery corresponding to Example 1 and Comparative Example 1 provided by the present invention;

[0044] Figure 9 This is a cycle performance diagram of the supercapacitor battery corresponding to Example 1 and Comparative Example 1 provided by the present invention.

[0045] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. Where the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0047] In the field of electrochemical energy storage, bismuth vanadate is considered an excellent carrier due to its non-toxicity, good compatibility, and favorable formation of reactive oxygen species, and has attracted considerable attention in the field of electrode materials. Furthermore, as an n-type semiconductor, bismuth vanadate, whose components are abundant on Earth, has been used as a photocatalytic oxidation material and is now increasingly being applied as an anode material in electrochemical water splitting.

[0048] However, as a semiconductor material, bismuth vanadate has a band gap of only 2.2 eV. While it exhibits a strong response to electrons, its electrochemical performance is unstable due to its high carrier-hole binding rate and slow interfacial hole transfer. Consequently, pure bismuth vanadate is unstable and prone to deactivation. Furthermore, bismuth vanadate has few active sites on its surface, and cations such as vanadium and bismuth ions preferentially occupy the surface, resulting in poor conductivity.

[0049] Currently, methods for modifying bismuth vanadate materials include preparing single atoms, constructing metal-organic framework (MOF) materials, constructing core-shell structures, or utilizing the Mott-Schottky effect between metals and carriers to increase conductivity, but these methods will lead to a decrease in the stability of bismuth vanadate materials.

[0050] In view of this, the present invention provides an anode active material, comprising oxygen-deficient bismuth vanadate and lanthanum chloride supported on the oxygen-deficient bismuth vanadate, wherein the anode active material has pores.

[0051] In the technical solution of the present invention, the bismuth vanadate in the anode active material has oxygen defects, which improves the conductivity of the bismuth vanadate electrode and promotes the separation of electrons and holes in the bismuth vanadate bulk phase; the lanthanum chloride in the anode active material promotes the injection efficiency of carriers on the surface of the bismuth vanadate electrode, changes the valence band structure of bismuth vanadate, and greatly improves the conductivity; in addition, the anode active material has pores, which provide sufficient mechanical strain space during the charge and discharge process, alleviate the volume expansion of bismuth, and improve the stability of the electrode.

[0052] In some embodiments of the present invention, the particle size of the anode active material is 4 to 6 μm. The particle size within the above range can ensure that the anode active material has a more suitable specific surface area, ensures that it has more reaction sites and is less likely to cause side reactions. In some embodiments of the present invention, the specific surface area of ​​the anode active material is 1.0 to 1.2 m 2 / g.

[0053] In some embodiments of the present invention, the molar ratio of oxygen-deficient bismuth vanadate to lanthanum chloride is 15 to 16. The mass ratio of oxygen-deficient bismuth vanadate to lanthanum chloride within the above range can ensure good conductivity and stability of the anode active material.

[0054] In some embodiments of the present invention, the porosity of the anode active material is 20-30%. The porosity within the above range can provide sufficient accommodation space for the insertion and extraction of lithium ions, thereby reducing the volume expansion of the anode active material and improving the stability of the battery. In some embodiments of the present invention, the anode active material has a honeycomb structure, which provides a good electrolyte infiltration channel, so that lithium ions (Li +) can be transported more efficiently within the cathode material, thereby improving rate performance and alleviating volume expansion.

[0055] The present invention also provides a method for preparing an anode active material, comprising the following steps: S10, mixing a bismuth source, a vanadium source, lanthanum chloride and ethylene glycol to obtain a mixed solution; S20, adjusting the pH of the mixed solution to less than 7, and performing heat treatment until a precipitate is generated to obtain the anode active material.

[0056] In the technical solution of the present invention, lanthanum chloride is added during the mixing process of the vanadium source and the bismuth source, and then the pH of the system is adjusted to acidic. The acidic environment changes the electronic properties of the vanadate ligand and accelerates the rate of the coordination reaction. Subsequently, heat treatment is performed so that the vanadate ions in the vanadium source and the bismuth ions in the bismuth source undergo a directional coordination reaction under the action of lanthanum chloride, so that the bismuth vanadate crystals grow in a directional manner to form a honeycomb structure. It should be noted that ethylene glycol is used as a solvent, which exhibits reducing properties under high temperature and acidic conditions. Oxygen vacancies are introduced during the synthesis of bismuth vanadate to form oxygen-deficient bismuth vanadate. Compared with the system without the addition of lanthanum chloride, the anode active material prepared by the present invention has a larger specific surface area, more active sites, and a larger porosity.

[0057] It should be noted that when lanthanum chloride is not added, the bismuth vanadate crystal structure will grow amorphously. When lanthanum chloride is added to the bismuth vanadate material, an interaction force will be generated between them, and this force will change the lattice structure of bismuth vanadate, forcing the bismuth vanadate crystal to grow in a directional manner.

[0058] In some embodiments of the present invention, in step S10: the bismuth source includes bismuth nitrate; the vanadium source includes ammonium vanadate; the molar ratio of bismuth ions in the bismuth source to vanadium ions in the vanadium source is 1:(0.8-1.2); the molar ratio of lanthanum ions in the lanthanum chloride to bismuth ions in the bismuth source is (0.326-0.408):5; and the mixing time is 20-40 minutes. Controlling the above conditions within an appropriate range can ensure that the vanadium source, bismuth source, and lanthanum chloride are mixed more evenly, and the final anode active material has better uniformity. Among them, the molar ratio of bismuth ions in the bismuth source to vanadium ions in the vanadium source is preferably 1:1. The molar ratio of vanadium ions to bismuth ions will significantly affect the electrochemical performance, structural stability, and structural characteristics of the electrode material prepared from the anode active material, especially the porosity.

[0059] In some embodiments of the present invention, in step S20, the pH is 1 to 3. A pH within the above range can ensure a faster coordination reaction rate between vanadate and bismuth ions.

[0060] In some embodiments of the present invention, in step S20, the heat treatment temperature is 110-140°C and the heat treatment duration is 3-5 hours. The heat treatment temperature significantly affects the crystal structure, morphology, and compositional stability of the anode active material. Heat treatment temperature and duration within the above ranges ensure that the coordination reaction between vanadate and bismuth ions, under the action of lanthanum chloride, allows for sufficient directional growth, resulting in a material with a suitable specific surface area and porosity.

[0061] In some embodiments of the present invention, step S20 includes adjusting the pH of the mixed solution to less than 7, performing heat treatment until a precipitate is formed, separating the solid from the liquid, collecting the solid, and vacuum drying the solid at 70° C. to obtain the anode active material. Vacuum drying can better preserve the electrochemical properties of the anode active material.

[0062] The present invention also provides a composite photoelectrode comprising a substrate, an anode active material supported on the surface of the substrate, and a conductive agent. The anode active material comprises the aforementioned anode active material or an anode active material prepared by the aforementioned method for preparing an anode active material. Therefore, the composite photoelectrode has all the beneficial effects of the aforementioned anode active materials and will not be further elaborated here.

[0063] In some embodiments of the present invention, the composite photoelectrode further comprises a binder for bonding the substrate to the anode active material: the substrate comprises copper foil; the conductive agent comprises conductive carbon black or carbon fiber; the binder comprises polyvinylidene fluoride (PVDF) or polyvinyl pyrrolidone (PVP).

[0064] The present invention also provides a supercapacitor battery, comprising a lithium metal sheet, a separator, an electrolyte, and the aforementioned anode active material, or the anode active material prepared by the aforementioned method for preparing the anode active material, or the aforementioned composite photoelectrode. Therefore, the supercapacitor battery has all the beneficial effects of the aforementioned anode active material or composite photoelectrode, which will not be detailed here. In some embodiments of the present invention, the specific capacity of the supercapacitor battery is 1059 to 1062 mAh / g.

[0065] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0066] Example 1

[0067] An anode active material is prepared by the following steps:

[0068] Step 1: Dissolve 5 mmol of Bi(NO3)3·5H2O in a dilute nitric acid solution and stir for 30 minutes to mix evenly to obtain a first solution.

[0069] Step 2: Dissolve 5 mmol of NH4VO3 in ethylene glycol to prepare a second solution, then mix the first solution and the second solution in a beaker and sonicate for 30 minutes.

[0070] Step 3: Add 80 mg of LaCl3 to the mixed solution after sonication and stir for 30 minutes to obtain a brown-yellow suspension.

[0071] Step 4: Add 1 mol / L NaOH to the brown-yellow suspension, adjust to pH = 3, transfer it to a 100 mL polytetrafluoroethylene kettle, and heat at 120° C. for 4 h to obtain a precipitate, which is filtered to obtain a solid product.

[0072] Step 5: Wash the solid product with deionized water and anhydrous ethanol three times, and dry it in vacuum at 80° C. to obtain a brown-yellow powder of bismuth vanadate / lanthanum chloride with oxygen defects, which is designated as BVO-LC.

[0073] Example 2

[0074] Compared with Example 1, Example 2 is different in that:

[0075] In step 3, 100 mg LaCl3 was added;

[0076] The final product was designated as BVO-LC2.

[0077] Example 3

[0078] Compared with Example 2, Example 3 is different in that:

[0079] In step 4, the heating temperature is 110°C;

[0080] The final product was designated as BVO-LC3.

[0081] Example 4

[0082] Compared with Example 2, Example 4 is different in that:

[0083] In step 4, the heating temperature is 130°C;

[0084] The final product was designated as BVO-LC4.

[0085] Example 5

[0086] Compared with Example 2, Example 5 is different in that:

[0087] In step 4, the heating temperature is 140°C;

[0088] The final product was designated as BVO-LC5.

[0089] Comparative Example 1

[0090] Comparative Example 1 is the same as Example 1 except that step 3 is omitted and the suspension in step 4 is replaced by the mixed solution after ultrasonication. The final product is recorded as BVO.

[0091] Performance Testing

[0092] The anode active materials BVO-LC in Example 1 and BVO in Comparative Example 1 were observed by scanning electron microscopy. The results were as follows: Figure 1 and Figure 2 shown.

[0093] Depend on Figure 1 It can be seen that BVO-LC is honeycomb-shaped and has no obvious nanoparticle clusters. At the same time, it exposes more active sites that promote the catalytic process, which is the main reason why the material has excellent chemical properties. Figure 2 As shown in Figure 2, the bismuth vanadate material without lanthanum chloride is square and has a smooth surface. It is worth noting that the average particle size of BVO-LC is 4.5μm, with a more porous structure, which is conducive to the transmission of lithium ions and improves its electrochemical performance.

[0094] The porosity and specific surface area of ​​the anode active materials BVO-LC of Examples 1 to 5 were measured using the BET method, where porosity = pore volume / total volume. The results are shown in Table 1.

[0095] Table 1 Porosity and specific surface area of ​​the anode active materials of Examples 1 to 5

[0096] Electrode name <![CDATA[Specific surface area (m 2 / g)]]> Porosity (%) BVO-LC 1.08 27 BVO-LC2 1.04 25 BVO-LC3 1.13 27 BVO-LC4 1.16 32 BVO-LC5 1.07 26

[0097] The crystal structures of the anode active materials BVO-LC, BVO-LC2, BVO-LC3, BVO-LC4 and BVO-LC5 in Examples 1 to 5 were tested by X-ray diffraction (XRD). Figure 3 shown.

[0098] like Figure 3 As shown in the figure, strong diffraction peaks appear at 18.92° and 28.94°, corresponding to the 110 and 121 crystal planes of BiVO4. In addition, with the increase of La loading, the peak of the 121 crystal plane in the anode active material samples of Examples 1 to 5 gradually increases. This shows that lanthanum chloride promotes the formation of the 121 crystal plane in the BiVO4 composite material.

[0099] The anode active materials BVO-LC and BVO in Example 1 and Comparative Example 1 were tested by bet to explore the information of the specific surface area of ​​the electrode materials. The results are as follows Figure 4 and Figure 5 shown.

[0100] like Figure 4 As shown in Figure 2, BVO-LC exhibits a type II isotherm, which also proves the existence of a mesoporous structure in the material. Figure 5 As shown in the figure, pure BiVO4 exhibits a type IV isotherm. The comparison between the two shows that La changes the pore structure of bismuth vanadate, exposing more active sites of the bismuth vanadate material and enhancing its electrochemical performance.

[0101] The materials in Example 1 and Comparative Example 1 were prepared into electrodes and assembled into button batteries, and the specific steps were as follows:

[0102] Electrode sheet preparation: The electrode sheets are all prepared using the conventional 811 ratio, that is, the active material: conductive agent: binder is 8:1:1. First, weigh the binder (the binder is polyvinylidene fluoride) and dissolve it in N-methyl-2-pyrrolidone to prepare a binder solution. Then weigh the anode active material and the conductive agent (the conductive agent is conductive carbon black), add them to the binder solution in sequence, stir evenly until viscous, and then apply it on a metal copper foil. After placing it in a vacuum drying oven at 100°C and drying for 8 hours, it is rolled and cut into circular electrode sheets to obtain the anode electrode sheet;

[0103] Assembly of the BVO-LC|Li supercapacitor: In a glove box, a lithium electrode sheet, separator, and anode electrode sheet were placed sequentially into a CR 2025 battery case. After adding electrolyte, the case was sealed with a mold to create a sandwich-structured supercapacitor. The BVO-LC supercapacitor served as the positive electrode, the lithium metal sheet as the negative electrode, and the Celgard 2500 microporous polypropylene membrane as the separator. The electrolyte consisted of 1.0M LiPF6 in ethyl methyl carbonate (EMC) / ethylene carbonate (EC) (EMC / EC = 1:1, volume ratio). Six battery packs were then subjected to performance testing.

[0104] The supercapacitor batteries corresponding to Example 1 and Comparative Example 1 were subjected to cyclic voltammetry (CV) curve tests. The CV curves of the initial cycles of BVO|Li lithium-ion batteries (LIBs) and BVO-LC|Li LIBs were obtained at a scan rate of 0.1 mV / s to explore the redox reactions occurring during the cycling of BVO and BVO-LC electrode materials. The results are shown in Figure 2. Figure 6 shown.

[0105] Depend on Figure 6 It can be seen that BiVO4-LC in the figure represents Example 1, BiVO4 represents Comparative Example 1, and the battery in Example 1 has 5 reduction peaks. The peak at 1.94V is mainly due to the decomposition of the electrolyte and the formation of the solid electrolyte (SEI) film. The peaks at 1.0V and 1.34V are mainly due to the V 5+The sharp negative peaks at 0.5V and 0.7V correspond to Li-Bi alloying. No obvious redox peaks of vanadium ions were observed in the CV of the battery in Comparative Example 1, and severe polarization occurred after a voltage of 1.8V. This was because the BVO product Li3VO4 dissolved in the liquid electrolyte, resulting in a large amount of capacity loss. The CV curve area and the number of redox peaks of BVO-LC are greater than those of BVO, which also shows that BVO-LC has higher capacity and better electrochemical performance.

[0106] The constant current charge / discharge (GCD) curve test of the supercapacitor batteries BVO|Li LIBs and BVO-LC|Li LIBs corresponding to Example 1 and Comparative Example 1 was conducted using a Xinwei battery test system to perform a constant current charge / discharge test, i.e., the battery was charged and discharged in cycles with a constant current. The GCD charge / discharge curve of the battery can be obtained, as shown in the following figure. Figure 7 shown.

[0107] like Figure 7 As shown in the first discharge cycle curve, a clear charge-discharge platform was observed. The 2.2V platform corresponds to the formation of the SEI film. The first charge-discharge specific capacities of BVO and BVO-LC were 663.2 mAh g -1 and 1059.3mAhg -1 , the first coulombic efficiency is about 96.1% and 98.2%. The electrochemical performance of BVO-LC is significantly better than that of BVO. The results show that BVO-LC has higher capacity and better electrochemical performance.

[0108] The supercapacitor batteries BVO|Li LIBs and BVO-LC|Li LIBs corresponding to Example 1 and Comparative Example 1 were tested at 0.1Ag. -1 to 1Ag -1 The rate performance under the test is tested, and the results are as follows Figure 8 shown.

[0109] like Figure 8 As shown, at 0.1Ag -1 The reversible capacity of BVO-LC|Li LIBs was measured to be 1073 mAh g -1 , which is much higher than the reversible capacity of BVO|Li LIBs (280 mAh g) -1 In addition, at 1Ag -1 The reversible capacity of BVO-LC|Li LIBs was measured to be 590 mAh g -1 , and when the current returns to 0.1A -1 The reversible capacity of BVO-LC|Li LIBs was measured to be 1030 mAh g -1. At different current densities, the capacity of BVO-LC|Li LIBs is greater than that of BVO|Li LIBs, which is attributed to the incorporation of lanthanum chloride particles into the electrode material, which enhances the electronic conductivity of the electrode material and improves the rate performance of BVO-LC|Li LIBs. At the same time, the encapsulation of lanthanum chloride not only alleviates the volume expansion of Bi, but also prevents the dissolution of Li3VO4, effectively improving the electrochemical performance. Regardless of the current density, BVO-LC|Li LIBs exhibits excellent Li + Storage capacity and cycling stability.

[0110] The cycle performance of the supercapacitor batteries BVO-LC|Li LIBs and BVO|Li LIBs corresponding to Example 1 and Comparative Example 1 was tested. The results are as follows: Figure 9 shown.

[0111] Depend on Figure 9 It can be seen that at 0.1Ag -1 After 100 cycles of charge and discharge, BVO-LC|Li LIBs showed excellent cycling stability and could provide 876 mAh g -1 The high specific capacity is much better than that of BVO|Li LIBs (243 mAh g -1 The capacity retention rates of BVO-LC|Li LIBs and BVO|Li LIBs after 100 charge-discharge cycles were 96.7% and 94%, respectively. Notably, the Coulombic efficiency of BVO-LC|Li LIBs remained above 96%. This remarkable long-term stability is attributed to the fact that the new structure formed by the incorporation of lanthanum chloride not only buffers the volume expansion of Bi during charge and discharge but also prevents the dissolution of Li3VO4, which helps to improve the cycling stability and electrochemical performance of the electrode.

[0112] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. An anode active material, characterized in that The anode active material includes oxygen-deficient bismuth vanadate and lanthanum chloride supported on the oxygen-deficient bismuth vanadate, and the anode active material has pores.

2. The anode active material according to claim 1, wherein The particle size of the anode active material is 4 to 6 μm; The molar ratio of the oxygen-deficient bismuth vanadate to lanthanum chloride is 15 to 16; The porosity of the anode active material is 20-30%; The specific surface area of ​​the anode active material is 1.0 to 1.2 m 2 / g; The anode active material has a honeycomb structure.

3. A method for preparing an anode active material according to claim 1 or 2, characterized in that: The following steps are involved: S10, mixing a bismuth source, a vanadium source, lanthanum chloride and ethylene glycol to obtain a mixed solution; S20, adjusting the pH of the mixed solution to less than 7, and performing heat treatment until a precipitate is generated to obtain the anode active material.

4. The method for preparing an anode active material according to claim 3, wherein: In step S10: The bismuth source includes bismuth nitrate; The vanadium source includes ammonium vanadate; The molar ratio of bismuth ions in the bismuth source to vanadium ions in the vanadium source is 1:(0.8-1.2); The molar ratio of lanthanum ions in the lanthanum chloride to bismuth ions in the bismuth source is (0.326-0.408):5; The mixing time is 20 to 40 minutes.

5. The method for preparing an anode active material according to claim 3, wherein: In step S20: The pH is 1 to 3; The temperature of the heat treatment is 110-140°C; The heat treatment time is 3 to 5 hours.

6. The method for preparing an anode active material according to claim 3, wherein: Step S20 includes: The pH of the mixed solution is adjusted to less than 7, and heat treatment is performed until a precipitate is generated. The solid and liquid are separated, and the solid is taken and vacuum dried at 70-90° C. to obtain the anode active material.

7. A composite photoelectrode, characterized in that: The composite photoelectrode includes a substrate, and an anode active material and a conductive agent loaded on the surface of the substrate, wherein the anode active material includes the anode active material as described in any one of claims 1 to 2 or the anode active material prepared by the preparation method of the anode active material as described in any one of claims 3 to 6.

8. The composite photoelectrode according to claim 7, wherein The composite photoelectrode further comprises a binder for bonding the substrate and the anode active material: The substrate comprises copper foil; The conductive agent includes conductive carbon black or carbon fiber; The binder includes polyvinylidene fluoride or polyvinyl pyrrolidone.

9. A supercapacitor battery, characterized in that: The supercapacitor battery includes a metal lithium sheet, a separator, an electrolyte, and the anode active material according to any one of claims 1 to 2 or the anode active material prepared by the preparation method of the anode active material according to any one of claims 3 to 6 or the composite photoelectrode according to any one of claims 7 to 8.

10. The supercapacitor battery according to claim 9, wherein: The specific capacity of the supercapacitor battery is 1059.0-1062.0 mAhg -1 .

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