Alkaline earth metal-doped barium vanadate positive electrode material, calcium ion battery and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTH CHINA ELECTRIC POWER UNIV
- Filing Date
- 2026-06-17
- Publication Date
- 2026-07-21
Smart Images
Figure CN122436430A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of calcium-ion battery technology, specifically relating to an alkaline earth metal-doped barium vanadate cathode material, a calcium-ion battery, and its preparation method. Background Technology
[0002] The extensive use of fossil fuels emits large amounts of carbon dioxide and other pollutants, causing serious environmental pollution. Furthermore, fossil fuels are non-renewable energy sources with limited reserves. In recent years, renewable, sustainable development, and low-carbon environmental protection have become crucial in the energy world. Many countries are currently vigorously developing clean and renewable energy sources such as solar, wind, hydro, geothermal, and biomass energy. However, these energy sources are often dependent on environmental factors such as geographical location, climate, and season, and are not directly usable. They often need to be converted into electricity, stored through electrochemical energy storage devices, and then transmitted to where they are needed to achieve clean energy utilization.
[0003] Among numerous electrochemical energy storage devices, calcium-ion batteries are considered a promising electrochemical energy storage technology due to their strong competitiveness in terms of cost, safety, and energy density. However, because of the limitations of calcium... 2+ The large ionic radius and high charge density of barium vanadate can lead to sluggish electrochemical reaction kinetics and unstable electrode material structure. Layered barium vanadate, as a positive electrode active material, has a large interlayer distance, which can accommodate Ca... 2+ The reversible insertion and extraction of layered barium vanadate. Currently, most methods for synthesizing layered barium vanadate materials require freeze-drying, and impurity phases are easily formed during synthesis. During cycling, the layered structure is prone to irreversible collapse, leading to rapid capacity decay. Therefore, there is an urgent need to propose a method for preparing and applying calcium-ion battery cathode materials that is simple to synthesize, produces products with high crystallinity, and exhibits excellent structural stability. Addressing the common defects of existing layered barium vanadate cathode materials, such as easy formation of impurity phases during synthesis, low crystallinity, easy collapse of the layered structure during cycling, and high cost due to reliance on freeze-drying, this invention optimizes the process and doping modification. Summary of the Invention
[0004] The main objective of this invention is to provide an alkaline earth metal-doped barium vanadate cathode material, a calcium-ion battery, and a method for preparing the same, in order to overcome the shortcomings of the prior art.
[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:
[0006] This invention provides a method for preparing an alkaline earth metal-doped barium vanadate cathode material, comprising:
[0007] Vanadium source, barium source and dopant are mixed and pretreated by plasma high-energy ball milling to obtain the precursor;
[0008] Furthermore, the precursor is dissolved in hydrogen peroxide solution and allowed to stand for aging, followed by a hydrothermal reaction to obtain an alkaline earth metal-doped barium vanadate cathode material.
[0009] The present invention also provides an alkaline earth metal-doped barium vanadate cathode material prepared by the aforementioned preparation method, wherein the crystallinity of the alkaline earth metal-doped barium vanadate cathode material is ≥90%.
[0010] This invention also provides a calcium-ion battery cathode, which includes the aforementioned alkaline earth metal-doped barium vanadate cathode material.
[0011] This invention also provides a calcium-ion battery, which includes at least the aforementioned alkaline earth metal-doped barium vanadate cathode material or calcium-ion battery cathode.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0013] (1) The crystallinity of the alkaline earth metal doped barium vanadate cathode material prepared by the present invention is increased from 77.75% by the traditional hydrothermal method to more than 90%, and the impurity phase is significantly reduced;
[0014] (2) The alkaline earth metal doped barium vanadate cathode material prepared by the present invention has a wide interlayer spacing of barium vanadate (e.g., 8.04 Å) which is suitable for the reversible insertion and extraction of calcium ions; it can still have a high capacity retention rate after 600 cycles and has excellent cycling performance.
[0015] (3) The preparation method provided by the present invention abandons freeze drying and uses traditional oven drying, which has a lower cost and is suitable for industrial mass production. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is the XRD pattern of the strontium-doped barium vanadate prepared in Example 1 of this invention;
[0018] Figure 2 This is an XRD comparison diagram of strontium-doped barium vanadate in Example 1 of the present invention and strontium-doped barium vanadate in Comparative Example 1.
[0019] Figure 3 This is a SEM image of the strontium-doped barium vanadate prepared in Example 1 of this invention;
[0020] Figure 4 This is a SEM image of the strontium-doped barium vanadate prepared in Comparative Example 1 of this invention.
[0021] Figure 5 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and barium vanadate without ball milling prepared in Comparative Example 1.
[0022] Figure 6 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and undoped barium vanadate prepared in Comparative Example 2.
[0023] Figure 7 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and overdoped barium vanadate prepared in Comparative Example 3.
[0024] Figure 8 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and unaged barium vanadate prepared in Comparative Example 4.
[0025] Figure 9 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and magnesium-doped barium vanadate prepared in Comparative Example 5.
[0026] Figure 10 This is a comparison of the capacity retention curves of strontium-doped barium vanadate prepared in Example 1 of the present invention and barium vanadate prepared by ball milling at an ion discharge frequency of 3kHz in Comparative Example 6.
[0027] Figure 11 This is a comparison curve of the capacity retention rate of strontium-doped barium vanadate prepared in Example 1 of the present invention and barium vanadate prepared by ball milling at an ion discharge frequency of 15 kHz in Comparative Example 7. Detailed Implementation
[0028] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0029] Specifically, as one aspect of the technical solution of this invention, a method for preparing an alkaline earth metal-doped barium vanadate cathode material includes:
[0030] Vanadium source, barium source and dopant are mixed and pretreated by plasma high-energy ball milling to obtain the precursor;
[0031] Furthermore, the precursor is dissolved in hydrogen peroxide solution and allowed to stand for aging, followed by a hydrothermal reaction to obtain an alkaline earth metal-doped barium vanadate cathode material.
[0032] In some preferred embodiments, the vanadium source includes any one or more combinations of vanadium pentoxide, ammonium metavanadate, and vanadium acetylacetonate, but is not limited thereto.
[0033] In some preferred embodiments, the barium source comprises a barium salt.
[0034] Furthermore, the barium salt includes any one or more combinations of barium chloride, barium nitrate, and barium acetate, but is not limited thereto.
[0035] In some preferred embodiments, the dopant includes a calcium source and / or a strontium source.
[0036] Furthermore, the dopant includes any one or more combinations of calcium chloride, calcium nitrate, calcium acetate, strontium chloride, strontium nitrate, and strontium acetate, and is not limited thereto.
[0037] In some preferred embodiments, the molar ratio of the vanadium source, barium source and dopant is 2:(5~12):(1~2).
[0038] In some preferred embodiments, the plasma high-energy ball milling pretreatment uses a ball-to-material mass ratio of 10:1 to 40:1, a plasma discharge frequency of 5 to 12 kHz, a rotation speed of 1200 to 1500 r / min, and a time of 10 to 26 h. The atmosphere during the ball milling process includes any one or more combinations of air, argon, and nitrogen.
[0039] In this invention, plasma high-energy ball milling is used to pre-treat raw materials to achieve micro-lattice pre-construction of precursors, improve the crystallinity of subsequent hydrothermal products and suppress the formation of impurity phases; at the same time, alkaline earth metal Ca / Sr ion doping modification is used to regulate the interlayer lattice spacing of barium vanadate, slow down the structural collapse during the calcium ion intercalation-deintercalation process and improve cycle stability.
[0040] In some preferred embodiments, the preparation method specifically includes:
[0041] (1) Vanadium source, barium source and dopant are placed in a plasma ball milling device for plasma high-energy ball milling pretreatment to obtain precursor; wherein, using plasma high-energy ball milling pretreatment as a process means to treat powder can obtain pre-embedded precursor; using calcium source and strontium source as dopant to insert into the vanadium-oxygen layer gap to obtain excellent cycle performance.
[0042] (2) Dissolve the precursor in hydrogen peroxide solution and stir to obtain a precursor solution;
[0043] (3) The precursor solution is allowed to stand and age, and then transferred to a hydrothermal reactor for hydrothermal reaction;
[0044] (4) After the hydrothermal reaction is completed, the material is cooled, washed, filtered and dried to obtain alkaline earth metal doped barium vanadate cathode material.
[0045] Furthermore, the concentration of the hydrogen peroxide solution is 5-15 wt%.
[0046] Furthermore, the stirring speed in step (2) is 600~1000 r / min, and the time is 1~10 h.
[0047] Furthermore, the settling and aging time in step (3) is 12~48h.
[0048] Furthermore, the temperature of the hydrothermal reaction in step (3) is 160~240℃.
[0049] Furthermore, the hydrothermal reaction time in step (3) is 16~28h.
[0050] Furthermore, the drying process in step (4) is carried out at a temperature of 40~80℃ for 6~24h.
[0051] In some preferred embodiments, the preparation method of the alkaline earth metal-doped barium vanadate cathode material includes the following steps:
[0052] Step 1: Weigh the vanadium source, barium source, and dopant according to the stoichiometric ratio and put them into a plasma ball mill for grinding.
[0053] Step 2: Dissolve the ball-milled precursor in a hydrogen peroxide solution of a certain concentration and stir at a certain speed for a certain period of time to dissolve it.
[0054] Step 3: After the obtained solution is allowed to stand and age for a period of time, it is transferred to a polytetrafluoroethylene reactor for hydrothermal reaction.
[0055] Step 4: Cooling, washing repeatedly with deionized water and anhydrous ethanol, filtration, and drying to obtain the alkaline earth metal-doped barium vanadate cathode material.
[0056] Preferably, in step one, the molar ratio of vanadium source, barium salt, and dopant is 2:9:1.
[0057] Preferably, in step one, the vanadium source includes vanadium pentoxide, ammonium metavanadate, or vanadium acetylacetonate.
[0058] Preferably, in step one, the barium salt includes barium chloride, barium nitrate, and barium acetate.
[0059] Preferably, in step one, the dopant includes calcium chloride, calcium nitrate, calcium acetate, strontium chloride, strontium nitrate, and strontium acetate.
[0060] Preferably, in step one, the ball-to-material mass ratio is 30:1, the plasma discharge frequency is 8kHz, the rotation speed is 1200r / min, the grinding time is 24 hours, and the atmosphere during the ball milling process is argon.
[0061] Preferably, in step two, the hydrogen peroxide concentration is between 5 and 15 wt%.
[0062] Preferably, in step two, the stirring speed is 600~1000 r / min.
[0063] Preferably, in step two, the stirring time is between 1 and 10 hours.
[0064] Preferably, in step three, the settling time is between 12 and 48 hours.
[0065] Preferably, in step three, the hydrothermal reaction temperature is between 160 and 240°C.
[0066] Preferably, in step three, the hydrothermal reaction time is between 16 and 28 hours.
[0067] Preferably, in step four, the drying temperature is between 40 and 80°C.
[0068] Preferably, in step four, the drying time is between 6 and 24 hours.
[0069] Another aspect of the present invention provides an alkaline earth metal-doped barium vanadate cathode material prepared by the aforementioned preparation method, wherein the crystallinity of the alkaline earth metal-doped barium vanadate cathode material is ≥90%.
[0070] Another aspect of the present invention provides a calcium-ion battery cathode, which includes the aforementioned alkaline earth metal-doped barium vanadate cathode material.
[0071] In some preferred embodiments, the aforementioned alkaline earth metal-doped barium vanadate cathode material is used as the cathode of a calcium-ion battery. The specific application method includes the following steps:
[0072] Step 1: Mix the above-prepared active material, conductive agent and polyvinylidene fluoride (PVDF) in a mass ratio of (6~8):(1~2):(1~2), add an appropriate amount of methylpyrrolidone, stir and mix evenly to obtain a uniformly mixed slurry;
[0073] Step 2: Coat the uniformly mixed slurry onto the current collector to obtain the positive electrode sheet;
[0074] Step 3: Using the above positive electrode sheet as the positive electrode, activated carbon cloth as the negative electrode, and an organic solution containing bis(trifluoromethanesulfonyl)imide calcium as the electrolyte, assemble the full cell.
[0075] Preferably, the conductive agents used in step one include conductive carbon black (super P) and Ketjen black (KB).
[0076] Preferably, the current collector used in step two includes carbon paper, aluminum foil, stainless steel foil, copper foil, etc.
[0077] Preferably, the electrolyte concentration in step three is between 0.5 and 1.5 mol / L for bis(trifluoromethanesulfonyl)imide calcium.
[0078] Preferably, the organic solvent in step three includes one or more of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) in any volume ratio.
[0079] Another aspect of the present invention provides a calcium-ion battery, which includes at least the aforementioned alkaline earth metal-doped barium vanadate cathode material or calcium-ion battery cathode.
[0080] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.
[0081] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.
[0082] Example 1
[0083] (1) In this embodiment, the molar ratio of vanadium source, barium source and dopant is 2:9:1. 193.5 mg of vanadium pentoxide, 1169 mg of barium chloride dihydrate and 141.9 mg of strontium chloride hexahydrate were weighed and placed in a plasma ball mill. The ball-to-material mass ratio was 30:1, the plasma discharge frequency was 8 kHz, the rotation speed was 1200 r / min, and argon was used as the atmosphere for the ball milling process. The milling was carried out for 24 hours to obtain the precursor.
[0084] (2) The obtained precursor was dissolved in 60 mL of 7.5 wt% hydrogen peroxide aqueous solution, and the mixture was kept at 700 r / min for 5 h and then allowed to stand for 24 h. The resulting solution was transferred to a polytetrafluoroethylene reactor, and the reactor was placed in an oven for hydrothermal reaction at 180 °C for 26 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a brick-red product. The product was washed three times with deionized water and three times with anhydrous ethanol, filtered, and dried in an oven at 60 °C for 12 h to obtain strontium-doped barium vanadate; its X-ray diffraction pattern (XRD) is shown below. Figure 1 As shown, the vanadium-oxygen interlayer spacing can reach 8.04 Å. Its scanning electron microscope (SEM) image is shown below. Figure 3 As shown.
[0085] (3) The obtained strontium-doped barium vanadate was used as the active material. The active material, conductive carbon black, and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1. An appropriate amount of methylpyrrolidone was added and stirred until uniformly mixed to obtain a uniformly mixed slurry. The slurry was coated onto carbon paper and dried in an oven at 80°C for 12 hours to form a positive electrode sheet. Using activated carbon cloth as the negative electrode, a calcium-ion full cell was assembled using 0.8 mol / L Ca(TFSi)2 electrolyte (the volume ratio of solvent EC:DMC:PC:EMC was 2:3:2:3) for electrochemical performance testing.
[0086] Example 2
[0087] (1) In this embodiment, the molar ratio of vanadium source, barium source and dopant is 2:5:2. 124.5 mg of ammonium metavanadate, 649.4 mg of barium chloride dihydrate and 156.4 mg of calcium chloride dihydrate were weighed and placed in a plasma ball mill. The ball-to-material mass ratio was 10:1, the plasma discharge frequency was 12 kHz, the rotation speed was 1500 r / min, and air was used as the atmosphere for the ball milling process. The milling was carried out for 10 hours to obtain the precursor.
[0088] (2) The obtained precursor was dissolved in 60 mL of 7.5 wt% hydrogen peroxide aqueous solution, and the mixture was kept at 600 r / min for 10 h and then allowed to stand for 12 h. The resulting solution was transferred to a polytetrafluoroethylene reactor, and the reactor was placed in an oven and hydrothermally reacted at 160 °C for 28 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a brick-red product. The product was washed three times with deionized water and anhydrous ethanol, filtered, and dried in an oven at 80 °C for 6 h to obtain calcium-doped barium vanadate.
[0089] (3) Prepare the slurry according to the method in Example 1. Coat the slurry onto aluminum foil and dry it in an oven at 80°C for 6 hours to form a positive electrode. Using activated carbon cloth as the negative electrode, assemble a full cell with 0.8 mol / L Ca(TFSi)2 electrolyte (the volume ratio of solvent EC / PC is 1:1, containing 10 vol.% FEC additive) and test its electrochemical performance.
[0090] Example 3
[0091] (1) In this embodiment, the molar ratio of vanadium source, barium source and dopant is 2:12:1. 370.6 mg of vanadium acetylacetonate, 1630.6 mg of barium acetate and 93.7 mg of calcium acetate monohydrate were weighed and placed in a plasma ball mill. The ball-to-material mass ratio was 40:1, the plasma discharge frequency was 5 kHz, the rotation speed was 1000 r / min, and nitrogen was used as the atmosphere for the ball milling process. The milling was carried out for 12 hours to obtain the precursor.
[0092] (2) The obtained precursor was dissolved in 60 mL of 15 wt% hydrogen peroxide aqueous solution, and the mixture was kept at 1000 r / min for 1 h and then allowed to stand for 48 h. The resulting solution was transferred to a polytetrafluoroethylene reactor, and the reactor was placed in an oven and hydrothermally reacted at 240 °C for 16 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a brick-red product. The product was washed three times with deionized water and anhydrous ethanol, filtered, and dried in an oven at 40 °C for 24 h to obtain calcium-doped barium vanadate.
[0093] (3) Prepare the slurry and electrode according to the method of Example 1, assemble the full cell and test it.
[0094] Example 4
[0095] (1) In this embodiment, the molar ratio of vanadium source, barium source and dopant is 2:10:2. 193.5 mg of vanadium pentoxide, 1390 mg of barium nitrate and 187.5 mg of calcium acetate monohydrate were weighed and placed in a plasma ball mill. The ball-to-material mass ratio was 30:1, the plasma discharge frequency was 7 kHz, the rotation speed was 1300 r / min, and argon was used as the atmosphere for the ball milling process. The milling was carried out for 26 hours to obtain the precursor.
[0096] (2) The obtained precursor was dissolved in 60 mL of 5 wt% hydrogen peroxide aqueous solution, and the mixture was kept at 600 r / min for 8 h and then allowed to stand for 36 h. The resulting solution was transferred to a polytetrafluoroethylene reactor, and the reactor was placed in an oven and hydrothermally reacted at 180 °C for 26 h. After the reaction was completed, the mixture was naturally cooled to room temperature to obtain a brick-red product. The product was washed three times with deionized water and three times with anhydrous ethanol, filtered, and dried in an oven at 60 °C for 12 h to obtain calcium-doped barium vanadate.
[0097] (3) Prepare the slurry and electrode according to the method of Example 2, assemble the full cell and test it.
[0098] Examples 5-13
[0099] Examples 5-13 are basically the same as Example 1, except that the dopant type, ball-to-material ratio and ball milling time in step one are changed according to Table 1. The rest are the same as in Example 1, and will not be repeated here.
[0100] Table 1
[0101]
[0102] The effects of Examples 5-13 are basically the same as those of Example 1.
[0103] Comparative Example 1
[0104] The method is the same as in Example 1, except that the precursor in step (1) is not ball-milled. A comparison of the XRD pattern of the prepared strontium-doped barium vanadate with that of the strontium-doped barium vanadate prepared in Example 1 is shown below. Figure 2 As shown, the crystallinity of strontium-doped barium vanadate increased from 77.75% to 96.10% after plasma ball milling. The scanning electron microscope (SEM) images of the strontium-doped barium vanadate prepared in this comparative example are shown below. Figure 4 As shown, the assembled full cell was tested, and its capacity retention curve was compared with that of Example 1. Figure 5 As shown, the capacity retention of un-ball-milled barium vanadate after 600 cycles at a current density of 75 mA / g is 50.79%.
[0105] Comparative Example 2
[0106] The method is the same as in Example 1, except that: in step (1), no dopant was added for modification. The full cell assembled with the positive electrode made of the obtained material was tested, and its capacity retention curve was compared with that of Example 1. Figure 6 As shown, the capacity retention of barium vanadate after 600 cycles at a current density of 75 mA / g increased from 37.50% to 54.22% after strontium doping modification.
[0107] Comparative Example 3
[0108] The method is the same as in Example 1, except that the molar ratio of vanadium pentoxide:barium source:dopant in step (1) is 2:9:3. The assembled full cell is tested, and its capacity retention curve is compared with that of Example 1. Figure 7 As shown, the capacity retention of overdoped barium vanadate after 600 cycles at a current density of 75 mA / g is 49.57%.
[0109] Comparative Example 4
[0110] The method is the same as in Example 1, except that the static aging treatment in step (2) is omitted. The assembled full cell is tested, and its capacity retention curve is compared with that of Example 1. Figure 8 As shown, barium vanadate without aging treatment retained 48.41% of its capacity after 600 cycles at a current density of 75 mA / g.
[0111] Comparative Example 5
[0112] The method is the same as in Example 1, except that magnesium is used instead of strontium doping. The assembled full cells are then tested, and their capacity retention curves are compared with those of Example 1. Figure 9 As shown, the capacity retention of magnesium-doped barium vanadate after 600 cycles at a current density of 75 mA / g is 29.46%.
[0113] Comparative Example 6
[0114] The method is the same as in Example 1, except that the plasma discharge frequency of the plasma ball mill is 3 kHz. The assembled full cells were tested, and their capacity retention curves were compared with those of Example 1. Figure 10 As shown, the capacity retention rate after 600 cycles at a current density of 75 mA / g is 51.38%.
[0115] Comparative Example 7
[0116] The method is the same as in Example 1, except that the plasma discharge frequency of the plasma ball mill is 15 kHz. The assembled full cells were tested, and their capacity retention curves were compared with those of Example 1. Figure 11 As shown, the capacity retention rate after 600 cycles at a current density of 75 mA / g is 47.01%.
[0117] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.
[0118] Table 2 summarizes the performance of the full cells assembled with barium vanadate cathodes in some of the embodiments and comparative examples.
[0119] Table 2
[0120]
[0121] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.
Claims
1. A method for preparing an alkaline earth metal-doped barium vanadate cathode material, characterized in that, include: Vanadium source, barium source and dopant are mixed and pretreated by plasma high-energy ball milling to obtain the precursor; Furthermore, the precursor is dissolved in hydrogen peroxide solution and allowed to stand for aging, followed by a hydrothermal reaction to obtain an alkaline earth metal-doped barium vanadate cathode material.
2. The preparation method according to claim 1, characterized in that, Specifically, it includes: (1) Vanadium source, barium source and dopant are placed in a plasma ball milling device for plasma high-energy ball milling pretreatment to obtain precursor; (2) Dissolve the precursor in hydrogen peroxide solution and stir to obtain a precursor solution; (3) The precursor solution is allowed to stand and age, and then transferred to a hydrothermal reactor for hydrothermal reaction; (4) After the hydrothermal reaction is completed, the alkaline earth metal doped barium vanadate cathode material is prepared by cooling, washing, filtration and drying.
3. The preparation method according to claim 2, characterized in that: The vanadium source includes any one or more combinations of vanadium pentoxide, ammonium metavanadate, and vanadium acetylacetonate. And / or, the barium source comprises a barium salt; preferably, the barium salt comprises any one or more combinations of barium chloride, barium nitrate, and barium acetate; And / or, the dopant includes a calcium source and / or a strontium source; preferably, the dopant includes any one or more combinations of calcium chloride, calcium nitrate, calcium acetate, strontium chloride, strontium nitrate, and strontium acetate; And / or, the molar ratio of the vanadium source, barium source and dopant is 2:(5~12):(1~2).
4. The preparation method according to claim 2, characterized in that: The plasma high-energy ball milling pretreatment uses a ball-to-material mass ratio of 10:1 to 40:1, a plasma discharge frequency of 5 to 12 kHz, a rotation speed of 1000 to 1500 r / min, and a time of 10 to 26 h. The atmosphere during the ball milling process includes any one or more combinations of air, argon, and nitrogen.
5. The preparation method according to claim 2, characterized in that: The concentration of the hydrogen peroxide solution is 5-15 wt%; And / or, the stirring speed in step (2) is 600~1000 r / min, and the time is 1~10 h.
6. The preparation method according to claim 2, characterized in that: The settling and aging time mentioned in step (3) is 12~48h; And / or, the temperature of the hydrothermal reaction in step (3) is 160~240℃; And / or, the hydrothermal reaction time in step (3) is 16~28h.
7. The preparation method according to claim 2, characterized in that: The drying process in step (4) is carried out at a temperature of 40~80℃ for 6~24h.
8. The alkaline earth metal-doped barium vanadate cathode material prepared by the preparation method according to any one of claims 1-7, characterized in that: The alkaline earth metal-doped barium vanadate cathode material has a crystallinity of ≥90%.
9. A positive electrode for a calcium-ion battery, characterized in that, Including the alkaline earth metal-doped barium vanadate cathode material as described in claim 8.
10. A calcium-ion battery, characterized in that, It includes at least the alkaline earth metal-doped barium vanadate cathode material of claim 8 or the calcium ion battery cathode of claim 9.