Mesoporous material, Prussian blue analogue cathode material, preparation method thereof and battery

Abstract

This application discloses a mesoporous material, a Prussian blue analogue cathode material, a preparation method thereof and a battery, belonging to the technical field of batteries. The preparation method of the mesoporous material comprises the following steps: sintering Na 3 Zr 2 Si 2 P 3 O 12 together with a mesoporous template to crystallize Na 3 Zr 2 Si 2 P 3 O 12 in the pores of the mesoporous template, and removing the template. The mesoporous material prepared by this method has a high specific surface area and can be used as a fast ion conductor in the Prussian blue analogue cathode material to improve the conductivity of the Prussian blue analogue cathode material and reduce side reactions caused by contact between the material and the electrolyte. The battery further prepared from the above Prussian blue analogue cathode material has good conductivity, rate performance and cycling performance.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a mesoporous material, a Prussian blue analogue positive electrode material, a preparation method thereof, and a battery. Background Art

[0002] In recent years, lithium-ion batteries have been widely used in new energy vehicles, energy storage and digital fields. Lithium resources are increasingly scarce. The positive electrode materials of lithium-ion batteries produced require lithium carbonate raw materials, but the price of lithium carbonate raw materials continues to rise. The sodium element of the same main group is widely distributed in the earth's crust and has abundant reserves. The two have similar physical and chemical properties. Sodium-ion batteries have the characteristics of abundant raw materials, long cycle life, and high safety performance. At present, they have once again become a research hotspot in the field of energy storage.

[0003] The cathode materials of sodium-ion batteries are mainly divided into transition metal oxides, polyanion compounds, Prussian blue analogs and organic compounds, etc. Among them, Prussian blue analogs are three-dimensional framework structures with a large number of sodium ion embedding sites and three-dimensional diffusion channels, so they are very suitable for storing sodium ions with larger ion radius.

[0004] The general structural formula of Prussian blue analogs is Na x M[Fe(CN) 6 ] 1-y □ y ·zH 2 O (can be abbreviated as MHCF or PBA), where M represents transition metal elements such as Fe, Co, Ni, Mn, etc., and □ represents Fe(CN) 6 Defects, x ranges from 0 < x < 2, y ranges from 0 < y < 1. The crystal structure of Prussian blue compounds is composed of transition metals M and Fe elements respectively with CN - The unique three-dimensional framework structure formed by the connection of N and C in Na + Stored in the interstices of the structure, water of crystallization is usually present on the surface and inside of the crystal.

[0005] Prussian blue analogs are generally face-centered cubic structures. The available channels and rigid structure of the open framework give PBA fast charge transfer kinetics and long cycle life. PBA can contain cations (Na + ) and diffuses it into the nano-gaps formed by transition metals and cyano ligands. However, PBA has at least one disadvantage of poor electronic conductivity, which limits its application in sodium-ion batteries to a certain extent.

[0006] In view of this, this application is hereby filed. Summary of the invention

[0007] One of the purposes of this application is to provide a method for preparing a mesoporous material, which can prepare Na2O3 that can be used as a fast ion conductor. 3 Zr 2 Si 2 P 3 O 12 Mesoporous materials.

[0008] The second purpose of the present application is to provide a mesoporous material prepared by the above-mentioned preparation method, which is beneficial to improving the conductivity of the Prussian blue analog positive electrode material.

[0009] The third object of the present application is to provide a Prussian blue analog positive electrode material coated with the above-mentioned mesoporous material.

[0010] The fourth object of the present application is to provide a method for preparing the above-mentioned Prussian blue analogue positive electrode material.

[0011] A fifth object of the present application is to provide a battery having the above-mentioned Prussian blue analogue positive electrode material.

[0012] This application can be implemented as follows:

[0013] In a first aspect, the present application provides a method for preparing a mesoporous material, which comprises the following steps: 3 Zr 2 Si 2 P 3 O 12 co-sintered with the mesoporous template to make Na 3 Zr 2 Si 2 P 3 O 12 Crystallization occurs in the pores of the mesoporous template and the template is removed.

[0014] In an alternative embodiment, Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio to the mesoporous template is 1:1 to 5:1.

[0015] In an alternative embodiment, Na 3 Zr 2 Si 2 P 3 O 12 Particle size D 50 It is a powder of 3-20μm.

[0016] In an optional embodiment, the mesoporous template includes at least one of the following features:

[0017] Feature 1: The mesoporous template includes a mesoporous silica template;

[0018] Feature 2: The pore size of mesopores in the mesoporous template is nanometer scale.

[0019] In an optional embodiment, sintering includes at least one of the following features:

[0020] Feature 1: Sintering temperature is 300-700℃;

[0021] Feature 2: Sintering time is 6-8h;

[0022] Feature 3: Sintering is carried out under air flow conditions;

[0023] Feature 4: Na 3 Zr 2 Si 2 P 3 O 12 It is first mixed evenly with the mesoporous template and then sintered.

[0024] In an alternative embodiment, the remover used to remove the template comprises hydrofluoric acid.

[0025] In a second aspect, the present application provides a mesoporous material prepared by the preparation method of any one of the aforementioned embodiments.

[0026] In a third aspect, the present application provides a Prussian blue analogue positive electrode material, which includes a Prussian blue analogue material and a coating material coated on the surface of the Prussian blue analogue, wherein the coating material includes the mesoporous material of the aforementioned embodiment.

[0027] In an alternative embodiment, the chemical formula of the Prussian blue analog is: Na x M[Fe(CN) 6 ] 1-y □ y ·zH 2 O, wherein 0<x<2, 0<y<1, and M includes at least one of Fe, Co, Ni and Mn.

[0028] In an optional embodiment, the coating material further includes at least one of activated carbon and graphene.

[0029] In an optional embodiment, the coating material includes a mesoporous material, activated carbon and graphene.

[0030] In an alternative embodiment, the mass of the mesoporous material is 0.01-1% of the total amount of the Prussian blue analog and the coating material.

[0031] In an alternative embodiment, the mass of graphene is 0.01-1% of the total amount of the Prussian blue analog and the coating material.

[0032] In an alternative embodiment, the mass of the activated carbon is 0.01-1% of the total amount of the Prussian blue analogue and the coating material.

[0033] In a fourth aspect, the present application provides a method for preparing a Prussian blue analogue positive electrode material as described in any of the aforementioned embodiments, comprising the following steps: sintering a mixture of a Prussian blue analogue and a coating material.

[0034] In an optional embodiment, the mixture of the Prussian blue analogue and the coating material includes at least one of the following features:

[0035] Feature 1: Mixing is carried out at 300-600rpm;

[0036] Feature 2: Mixing time is 10-30min;

[0037] Feature 3: Mixing is carried out under protective atmosphere conditions.

[0038] In an optional embodiment, the sintering of the Prussian blue analogue with the coating material includes at least one of the following features:

[0039] Feature 1: Sintering temperature is 100-200℃;

[0040] Feature 2: Sintering time is 6-10h;

[0041] Feature 3: Sintering is carried out under protective atmosphere conditions.

[0042] In an alternative embodiment, the preparation of the Prussian blue analogue comprises: mixing a first solution, a second solution, and a third solution;

[0043] The first solution contains a divalent iron salt and a reducing agent, the second solution contains a divalent cobalt salt and a reducing agent, and the third solution contains a sodium salt.

[0044] In an optional embodiment, the first solution includes sodium ferrocyanide decahydrate; and / or, the second solution includes at least one of cobaltous chloride and cobaltous sulfate; and / or, the third solution includes at least one of sodium chloride and sodium sulfate; and / or, the reducing agent includes ascorbic acid.

[0045] In an optional embodiment, the mixture of the first solution, the second solution and the third solution includes at least one of the following characteristics:

[0046] Feature 1: dropping the first solution and the second solution into the third solution;

[0047] Feature 2: Mixing is carried out under protective atmosphere conditions.

[0048] In an alternative embodiment, the drip rate is 1-30 mL / h.

[0049] In an optional embodiment, the method further includes subjecting the suspension obtained by mixing to solid-liquid separation and drying.

[0050] In a fifth aspect, the present application provides a battery, wherein the positive electrode material is the Prussian blue analog positive electrode material of any one of the aforementioned embodiments.

[0051] The beneficial effects of this application include:

[0052] The method provided in the present application can prepare a mesoporous material with nanometer-scale pore size and large specific surface area, which can be used as a fast ion conductor in a Prussian blue analog positive electrode material, thereby improving the conductivity of the Prussian blue analog positive electrode material and reducing the side reactions caused by the contact between the material and the electrolyte. The battery further prepared from the above-mentioned Prussian blue analog positive electrode material has good conductivity, rate capability and cycle performance. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0054] The mesoporous material, Prussian blue analogue positive electrode material, preparation method thereof and battery provided in the present application are described in detail below.

[0055] The present application proposes a method for preparing a mesoporous material, which comprises the following steps: 3 Zr 2 Si 2 P 3 O 12 co-sintered with the mesoporous template to make Na 3 Zr 2 Si 2 P 3 O 12 Crystallization occurs in the pores of the mesoporous template and the template is removed.

[0056] In some alternative embodiments, Na 3 Zr 2 Si 2 P 3 O 12It can be obtained by the following method: Take 6.5g analytical pure citric acid, dissolve it in 15mL water to make a citric acid solution, and add 8.4mL of ethyl orthosilicate, stir until the grease disappears, that is, the hydrolysis is complete. Then add 15mL of supersaturated solution containing 5.542g of trisodium citrate, and drop the solution containing ZrO while stirring. 2 46.44 mL of zirconium oxychloride solution with a concentration of 99.6 mg / ml was added. There was no sign at first, but then a white precipitate appeared. 2 O 5 13.6 mL of 98.37 mg / mL phosphoric acid solution was added, and the precipitate still existed. A certain amount of analytical pure ammonia solution was added, and the precipitate disappeared. The resulting colorless transparent solution was Na 3 Zr 2 Si 2 P 3 O 12 Under nitrogen atmosphere, the inlet temperature was 214℃ and the outlet temperature was 135℃. 3 Zr 2 Si 2 P 3 O 12 The solution was spray dried to obtain white powder Na 3 Zr 2 Si 2 P 3 O 12 .

[0057] It should be noted that in other embodiments, any other feasible method can be used to prepare Na 3 Zr 2 Si 2 P 3 O 12 .

[0058] The above Na 3 Zr 2 Si 2 P 3 O 12 For example, the particle size D 50 It is a powder of 3-20μm.

[0059] As a reference, Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio to the mesoporous template can be 1:1 to 5:1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, or any other value within the range of 1:1 to 5:1.

[0060] If Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na to the mesoporous template is lower than 1:1, such as 0.5:1, which may lead to insufficient crystallinity. 3 Zr 2 Si 2 P 3 O 12 A mass ratio to the mesoporous template higher than 5:1, such as 6:1, can easily lead to stacking and crystallization, affecting performance.

[0061] The mesoporous template may be, for example, a mesoporous silica template. In addition, mesoporous templates made of other materials may also be used.

[0062] In the present application, the mesopores in the mesoporous template have a nanometer-scale pore size, so that the obtained mesoporous material has a nanometer-scale pore size, thereby obtaining a larger specific surface area, which is beneficial to improving the conductivity of the Prussian blue analog positive electrode material.

[0063] As a reference, Na 3 Zr 2 Si 2 P 3 O 12 The sintering temperature with the mesoporous template can be 300-700°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or 700°C, or any other value within the range of 300-700°C.

[0064] If the sintering temperature is lower than 300℃, Na 3 Zr 2 Si 2 P 3 O 12 It cannot fully crystallize in the pores of the mesoporous template; if the sintering temperature is higher than 700°C, it is easy to cause excessive crystallinity and affect the performance.

[0065] The sintering time may be 6-8 h, such as 6 h, 6.5 h, 7 h, 7.5 h or 8 h, etc., or any other value within the range of 6-8 h.

[0066] In some preferred embodiments, sintering is performed under air flow conditions to promote Na 3 Zr 2 Si 2 P 3 O 12 Crystallizes in the pores of the mesoporous template. 3 Zr 2 Si 2 P3 O 12 It is first mixed evenly with the mesoporous template and then sintered.

[0067] For example, in the process of preparing the mesoporous material, the template removal agent may include hydrofluoric acid. In addition, other agents that do not react with Na 3 Zr 2 Si 2 P 3 O 12 Materials that are reactive and capable of removing the mesoporous template.

[0068] Correspondingly, the present application provides a mesoporous material, which is prepared by the above-mentioned preparation method.

[0069] The obtained mesoporous material has nanometer-scale pore size and large specific surface area, and can be used as a fast ion conductor in a Prussian blue analog positive electrode material, thereby improving the conductivity of the Prussian blue analog positive electrode material and reducing side reactions caused by contact between the material and the electrolyte.

[0070] In addition, the present application also provides a Prussian blue analogue positive electrode material, which includes a Prussian blue analogue material and a coating material coated on the surface of the Prussian blue analogue, and the coating material includes the above-mentioned mesoporous material.

[0071] For reference, the chemical formula of Prussian blue analogue is: Na x M[Fe(CN) 6 ] 1-y □ y ·zH 2 O, wherein 0<x<2, 0<y<1, M includes at least one of Fe, Co, Ni and Mn, and in addition, M may also include any other transition metal element that can be used in the positive electrode material.

[0072] In the present application, the coating material on the surface of the Prussian blue analogue may also include at least one of activated carbon and graphene.

[0073] In some embodiments, the coating material on the surface of the Prussian blue analog may include both mesoporous material and activated carbon. In other embodiments, the coating material on the surface of the Prussian blue analog may include both mesoporous material and graphene. In other embodiments, the coating material on the surface of the Prussian blue analog may include both mesoporous material, activated carbon and graphene.

[0074] It should be noted that the inventors proposed that: during the synthesis of Prussian blue analogs, a lot of crystal water will be generated, the electronic connection channel of the particle diameter will be blocked, and side reactions with electrolytes will occur. The crystal water in the lattice gaps is easy to occupy the sodium storage sites and Na + The deintercalation channel leads to the reduction of Na content in the material and Na+ The migration rate is reduced. The present application can effectively absorb crystal water and solve the above problems by coating activated carbon on the surface of the Prussian blue analog.

[0075] In addition, by coating with graphene, the conductivity of the Prussian blue analogue cathode material can be further improved in combination with the mesoporous material, and the side reactions caused by the contact between the material and the electrolyte can be reduced. By simultaneously coating with the mesoporous material, activated carbon and graphene, the obtained Prussian blue analogue cathode material can have lower crystal water and higher conductivity, which is beneficial to improve the electrochemical performance of the corresponding sodium ion battery.

[0076] For reference, the mass of the mesoporous material can be 0.01-1% of the total amount of the Prussian blue analogue and the coating material, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or any other value within the range of 0.01-1%.

[0077] If the amount of the mesoporous material is too small, the effect of improving the conductivity of the Prussian blue analog positive electrode material is not obvious; if the amount of the mesoporous material is too large, it is easy to cause the capacity of the Prussian blue analog positive electrode material to decrease.

[0078] The mass of graphene can be 0.01-1% of the total amount of the Prussian blue analog and the coating material, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or any other value within the range of 0.01-1%.

[0079] If the amount of graphene used is too little, the effect of improving the conductivity of the Prussian blue analogue positive electrode material is not obvious; if the amount of graphene used is too much, it is easy to cause the capacity of the Prussian blue analogue positive electrode material to decrease.

[0080] The mass of the activated carbon can be 0.01-1% of the total amount of the Prussian blue analogue and the coating material, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or any other value within the range of 0.01-1%.

[0081] If the amount of activated carbon used is too little, the effect of absorbing the crystal water of the Prussian blue analog positive electrode material is not obvious; if the amount of activated carbon used is too much, it is easy to cause the capacity of the Prussian blue analog positive electrode material to decrease.

[0082] Accordingly, the present application also provides a method for preparing the above-mentioned Prussian blue analogue positive electrode material, which may include the following steps: sintering a mixture of the Prussian blue analogue and the coating material.

[0083] The mixing of the Prussian blue analogue and the coating material can be carried out in a high-speed mixer, and the corresponding mixing speed can be 300-600rpm, such as 300rpm, 350rpm, 400rpm, 450rpm, 500rpm, 550rpm or 600rpm, etc., or any other value within the range of 300-600rpm.

[0084] The mixing time may be 10-30 min, such as 10 min, 15 min, 20 min, 25 min or 30 min, etc., or any other value within the range of 10-30 min.

[0085] The above mixing process can be carried out under protective atmosphere conditions.

[0086] It should be noted that the “protective atmosphere” mentioned in the present application may be, for example, an inert gas (such as helium, argon, etc.) atmosphere or a nitrogen atmosphere.

[0087] For reference, the sintering temperature of the Prussian blue analogue and the coating material may be 100-200°C, such as 100°C, 120°C, 150°C, 180°C or 200°C, or any other value within the range of 100-200°C.

[0088] The sintering time of the Prussian blue analogue and the coating material can be 6-10 h, such as 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h or 10 h, etc., or any other value within the range of 6-10 h.

[0089] The sintering of the Prussian blue analogue and the coating material can also be carried out under protective atmosphere conditions.

[0090] Through the sintering process, the moisture adsorbed by the activated carbon can be removed, and at the same time, the coating can be better combined with the Prussian blue analog material body, thereby improving the shortcomings of the Prussian blue analog material and improving its performance.

[0091] In some embodiments, the preparation of the above-mentioned Prussian blue analogue may include: mixing a first solution, a second solution and a third solution; wherein the first solution contains a divalent iron salt and a reducing agent, the second solution contains a divalent cobalt salt and a reducing agent, and the third solution contains a sodium salt.

[0092] The first solution may exemplarily but not limitatively include sodium ferrocyanide decahydrate, the second solution may exemplarily but not limitatively include at least one of cobaltous chloride and cobaltous sulfate, and the third solution may exemplarily but not limitatively include at least one of sodium chloride and sodium sulfate.

[0093] The reducing agent may illustratively but not limitedly include ascorbic acid, and any other reducing substance that can be used in the preparation of Prussian blue analogs may also be used to prevent iron ions and cobalt ions from being oxidized.

[0094] The first solution, the second solution and the third solution may be mixed by dropping the first solution and the second solution into the third solution. This method is more conducive to controlling the uniformity of the reaction than mixing the three solutions simultaneously.

[0095] By way of example, the dripping rate may be 1-30 mL / h, such as 1 mL / h, 2 mL / h, 5 mL / h, 10 mL / h, 15 mL / h, 20 mL / h, 25 mL / h or 30 mL / h, or any other value within the range of 1-30 mL / h.

[0096] If the droplet acceleration rate is too slow, the reaction rate may be too slow, affecting the production capacity; if the droplet acceleration rate is too fast, the reaction may be incomplete, affecting the material performance.

[0097] The mixing of the first solution, the second solution and the third solution can also be carried out under protective atmosphere conditions to prevent the iron ions and the cobalt ions from being oxidized.

[0098] Furthermore, the suspension obtained by mixing the first solution, the second solution and the third solution is subjected to solid-liquid separation and dried.

[0099] The solid-liquid separation may be carried out by centrifugal washing, and the drying may be carried out by vacuum drying. The temperature may be 120° C. by way of example but not limitation, and the time may be 24 hours by way of example but not limitation.

[0100] In addition, the present application also provides a battery (sodium ion battery), whose positive electrode material is the above-mentioned Prussian blue analog positive electrode material.

[0101] The battery has good rate performance and cycle performance.

[0102] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0103] Example 1

[0104] This embodiment provides a Prussian blue analogue positive electrode material, which is prepared by the following steps:

[0105] Prussian blue analogs, fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12, activated carbon (commercially available) and graphene (commercially available) were added to the mechanical fusion device, and the fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 , activated carbon (commercially available) and graphene (commercially available) accounted for the mixed material (Prussian blue analog + fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 + activated carbon + graphene) with a total mass of 0.1wt%, mixed at high speed (400rpm) for 20min in a nitrogen atmosphere. Then put it into a furnace filled with nitrogen atmosphere, sintered at 100℃ for 10h, and then taken out of the furnace and transferred to a glove box filled with nitrogen for sieving, finally obtaining fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 , activated carbon and graphene multi-modified (coated) Prussian blue analogue cathode material Na 1.31 Co[Fe(CN) 6 ] 0.81 □ 0.19 1.02H 2 O.

[0106] Among them, Prussian blue analog Na 1.31 Co[Fe(CN) 6 ] 0.81 □ 0.19 2.79H 2 O was obtained by the following method: 2mmol of sodium ferrocyanide decahydrate and 10mg of ascorbic acid were dissolved in 100mL of deionized water to form a first solution, 2mmol of cobaltous chloride and 10mg of ascorbic acid were dissolved in 100mL of deionized water to form a second solution, and 1mol of sodium chloride was dissolved in 100mL of deionized water to form a third solution. The temperature of the third solution was maintained at 25°C by a constant temperature water bath. The first solution and the second solution were added dropwise to the third solution at the same time using a peristaltic pump, and the dropwise addition rate was 10mL / h. The reaction was continuously stirred during the entire reaction process, and nitrogen was introduced as a protective atmosphere. After the first solution and the second solution were added dropwise, the resulting suspension was fully centrifuged and washed, and vacuum dried at 120°C for 24h to obtain Prussian blue analog Na 1.31 Co[Fe(CN) 6 ] 0.81 □ 0.19 2.79H 2 O.

[0107] Fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 It was obtained by the following method: 6.5g of analytical pure citric acid was dissolved in 15mL of water to make a citric acid solution, and 8.4mL of ethyl orthosilicate was added and stirred until the grease disappeared, indicating that the hydrolysis was complete. Then 15mL of a supersaturated solution containing 5.542g of trisodium citrate was added, and a solution containing ZrO was added dropwise while stirring. 2 46.44 mL of zirconium oxychloride solution with a concentration of 99.6 mg / ml was added. There was no sign at first, but then a white precipitate appeared. 2 O 5 13.6 mL of 98.37 mg / mL phosphoric acid solution was added, and the precipitate still existed. A certain amount of analytical pure ammonia solution was added, and the precipitate disappeared. The resulting colorless transparent solution was Na 3 Zr 2 Si 2 P 3 O 12 Under nitrogen atmosphere, the inlet temperature was 214℃ and the outlet temperature was 135℃. 3 Zr 2 Si 2 P 3 O 12 The solution was spray dried to obtain white powder Na 3 Zr 2 Si 2 P 3 O 12 . Will Na 3 Zr 2 Si 2 P 3 O 12 and a mesoporous silica template, wherein: the mesoporous silica template and Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na is 1:2; then sintered at 300 ° C under air flow for 6 hours 3 Zr 2 Si 2 P 3 O 12 The nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 .

[0108] Example 2

[0109] The difference between this embodiment and embodiment 1 is that the positive electrode material of the Prussian blue analogue is Na 1.25 Co[Fe(CN) 6 ] 0.76 □ 0.24 1.95H 2 O.

[0110] Prussian blue analogs, fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 The sintering of , activated carbon (commercially available) and graphene (commercially available) was carried out at 150°C for 8h.

[0111] Prussian blue analogues are Na 1.25 Co[Fe(CN) 6 ] 0.76 □ 0.24 3.45H 2 O. In the preparation process of the Prussian blue analog, the third solution is formed by dissolving 6 mol of sodium chloride in 100 mL of deionized water, and the other conditions are the same as those in Example 1.

[0112] Fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 During the preparation process, the mesoporous silica template and Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na is 1:3; then sintered under air flow at 500 ° C for 7 hours to make Na 3 Zr 2 Si 2 P 3 O 12 Crystallization is carried out in the pores of the mesoporous silica template, and then the template is removed with HF acid. The rest of the process is the same as in Example 1.

[0113] Example 3

[0114] The difference between this embodiment and embodiment 1 is that the positive electrode material of the Prussian blue analogue is Na 1.28 Co[Fe(CN) 6 ] 0.79 □ 0.21 1.08H 2 O.

[0115] Prussian blue analogs, fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 The sintering of activated carbon (commercially available) and graphene (commercially available) was carried out at 180°C for 6h.

[0116] Prussian blue analogues are Na 1.28 Co[Fe(CN) 6 ] 0.79 □ 0.21 2.55H 2 In the preparation process of the Prussian blue analog, the second solution is formed by dissolving 3 mmol of cobaltous sulfate and 10 mg of ascorbic acid in 100 mL of deionized water, and the third solution is formed by dissolving 3 mol of sodium sulfate in 100 mL of deionized water, and the other conditions are the same as those in Example 1.

[0117] Fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 During the preparation process, the mesoporous silica template and Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na is 1:3; then sintered under air flow at 600 ° C for 6 hours 3 Zr 2 Si 2 P 3 O 12 Crystallization is carried out in the pores of the mesoporous silica template, and then the template is removed with HF acid. The rest of the process is the same as in Example 1.

[0118] Example 4

[0119] The difference between this embodiment and embodiment 1 is that the positive electrode material of the Prussian blue analogue is Na 1.27 Co[Fe(CN) 6 ] 0.78 □ 0.20 1.60H 2 O.

[0120] Prussian blue analogs, fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12The sintering of activated carbon (commercially available) and graphene (commercially available) was carried out at 150°C for 6h.

[0121] Prussian blue analogues are Na 1.27 Co[Fe(CN) 6 ] 0.78 □ 0.20 2.60H 2 In the preparation process of the Prussian blue analog, the second solution is formed by dissolving 4 mmol of cobaltous sulfate and 10 mg of ascorbic acid in 100 mL of deionized water, and the third solution is formed by dissolving 4 mol of sodium sulfate in 100 mL of deionized water, and the other conditions are the same as those in Example 1.

[0122] Fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 During the preparation process, the mesoporous silica template and Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na is 1:3; then sintered at 700 ° C under air flow conditions for 8 hours 3 Zr 2 Si 2 P 3 O 12 Crystallization is carried out in the pores of the mesoporous silica template, and then the template is removed with HF acid. The rest of the process is the same as in Example 1.

[0123] Example 5

[0124] The difference between this embodiment and embodiment 1 is that the positive electrode material of the Prussian blue analogue is Na 1.24 Co[Fe(CN) 6 ] 0.77 □ 0.23 1.80H 2 O.

[0125] Prussian blue analogs, fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 The sintering of , activated carbon (commercially available) and graphene (commercially available) was carried out at 120°C for 10 h.

[0126] Prussian blue analogues are Na 1.24 Co[Fe(CN) 6 ] 0.77 □0.23 3.22H 2 In the preparation process of the Prussian blue analog, the first solution is formed by dissolving 2 mmol of sodium ferrocyanide decahydrate and 15 mg of ascorbic acid in 100 mL of deionized water, the second solution is formed by dissolving 2 mmol of cobaltous chloride and 15 mg of ascorbic acid in 100 mL of deionized water, and the third solution is formed by dissolving 5 mol of sodium chloride in 100 mL of deionized water, and the other conditions are the same as those in Example 1.

[0127] Fast ion conductor nano-mesoporous Na 3 Zr 2 Si 2 P 3 O 12 During the preparation process, the mesoporous silica template and Na 3 Zr 2 Si 2 P 3 O 12 The mass ratio of Na is 1:1; then sintered under air flow at 600 ° C for 6 hours 3 Zr 2 Si 2 P 3 O 12 Crystallization is carried out in the pores of the mesoporous silica template, and then the template is removed with HF acid. The rest of the process is the same as in Example 1.

[0128] Comparative Example 1

[0129] The difference between this comparative example and Example 1 is that this comparative example is a Prussian blue analog Na without any coating. 1.31 Co[Fe(CN) 6 ] 0.81 □ 0.19 2.79H 2 O.

[0130] Test example

[0131] The positive electrode materials obtained in the above examples and comparative examples were made and tested according to the following steps. Weigh 9.2 grams of positive electrode material, 0.4 grams of conductive carbon black, 0.4 grams of PVDF and 10 grams of organic solvent N-methylpyrrolidone, add them into a beaker, and stir continuously at room temperature for 1 hour at a speed of 1000 rpm / min to make a mixed slurry. The obtained mixed positive electrode slurry is then coated on an aluminum foil with a collector thickness of 16 μm and vacuum dried at 120°C for 120 minutes. Then use a roller press to press the sheet, and the thickness after rolling is 160 μm.

[0132] The negative electrode uses metal sodium foil, the separator is Green GRE-16P, and the electrolyte is 1 mol / L NaClO4 Ethylene carbonate (EC) and diethyl carbonate (DEC) (volume ratio 1:1) solution was prepared. CR2032 button cells were prepared in a glove box with argon atmosphere. The prepared battery was placed at room temperature for 2 hours to allow the electrolyte and the material to fully contact. The button cells were charged and discharged using a Xinwei battery tester at a cutoff voltage of 3.0 to 4.3 V at room temperature of 25°C, focusing on water content, 0.2C discharge capacity and 1C cycle performance. The relevant test results are shown in Table 1.

[0133] Table 1 Test results

[0134]

[0135] It can be seen from Table 1 that, relative to the comparative example, the Prussian blue analogue positive electrode material provided in the example has low water content, good conductivity (good rate performance) and excellent cycle performance.

[0136] In summary, the mesoporous material provided in the present application has a high specific surface area and can be used as a fast ion conductor in a Prussian blue analog positive electrode material to improve the conductivity of the Prussian blue analog positive electrode material and reduce the side reactions caused by the contact between the material and the electrolyte. The preparation method of the corresponding Prussian blue analog positive electrode material is simple, easy to operate, and suitable for large-scale production. The battery further prepared from the above-mentioned Prussian blue analog positive electrode material has good conductivity, rate performance and cycle performance.

[0137] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0138] Industrial Applicability

[0139] The mesoporous material provided in the present application has a high specific surface area and can be used as a fast ion conductor in a Prussian blue analogue positive electrode material to improve the conductivity of the Prussian blue analogue positive electrode material and reduce the side reactions caused by the contact between the material and the electrolyte. In addition, the present application can effectively absorb crystal water and solve the problem that the crystal water in the lattice gap easily occupies the sodium storage site and N a+ The deintercalation channel leads to the reduction of Na content in the material and Na +The invention relates to a method for preparing a positive electrode material of a Prussian blue analogue, wherein the positive electrode material of the Prussian blue analogue is coated with graphene, and the conductivity of the positive electrode material of the Prussian blue analogue can be further improved by combining with a mesoporous material, thereby reducing the side reactions caused by the contact between the material and the electrolyte. By simultaneously coating the mesoporous material, activated carbon and graphene, the obtained positive electrode material of the Prussian blue analogue can have a lower crystal water and a higher conductivity, which is beneficial to improve the electrochemical performance of the corresponding sodium ion battery. The preparation method of the corresponding positive electrode material of the Prussian blue analogue is simple, easy to operate, and suitable for large-scale production. The battery further prepared by the above-mentioned positive electrode material of the Prussian blue analogue has good conductivity, rate capability and cycle performance.

Claims

1. A Prussian blue analogue cathode material, characterized in that, the Prussian blue analogue cathode material comprises a Prussian blue analogue material and a coating material coated on the surface of the Prussian blue analogue, and the coating material comprises a mesoporous material, activated carbon and graphene; The preparation of the mesoporous material comprises the following steps: Mixing Na 3 Zr 2 Si 2 P 3 O 12 with a mesoporous template and sintering them together to cause Na 3 Zr 2 Si 2 P 3 O 12 to crystallize in the pores of the mesoporous template, and then removing the template; The Na 3 Zr 2 Si 2 P 3 O 12 has a mass ratio to the mesoporous template of 1:1 to 5:1; the Na 3 Zr 2 Si 2 P 3 O 12 is a powder with a particle size D 50 of 3 - 20 μm; the sintering temperature is 300 - 700 °C; the sintering time is 6 - 8 h; the sintering is carried out under an air flow condition; The chemical formula of the Prussian blue analog is: Na x M[Fe(CN) 6 1-y ·□ y ·zH 2 O, where 0 < x < 2, 0 < y < 1, and M includes at least one of Fe, Co, Ni, and Mn;​ the mass of the mesoporous material is 0.01 - 1% of the total amount of the Prussian blue analogue and the coating material; the mass of the graphene is 0.01 - 1% of the total amount of the Prussian blue analogue and the coating material; the mass of the activated carbon is 0.01 - 1% of the total amount of the Prussian blue analogue and the coating material.

2. The Prussian blue analogue cathode material according to claim 1, characterized in that, the mesoporous template comprises at least one of the following characteristics: Characteristic 1: The mesoporous template comprises a mesoporous silica template; Characteristic 2: The mesoporous pore diameter in the mesoporous template is nanoscale.

3. The Prussian blue analogue cathode material according to claim 1, characterized in that, The Na 3 Zr 2 Si 2 P 3 O 12 is first uniformly mixed with the mesoporous template and then sintered.

4. The Prussian blue analogue cathode material according to any one of claims 1 - 3, characterized in that, the removing agent used for removing the template comprises hydrofluoric acid.

5. A preparation method of the Prussian blue analogue cathode material according to any one of claims 1 - 4, characterized in that, it comprises the following steps: sintering a mixture of the Prussian blue analogue and the coating material.

6. The preparation method according to claim 5, characterized in that, the mixing of the Prussian blue analogue and the coating material comprises at least one of the following characteristics: Characteristic 1: The mixing is carried out under the condition of 300 - 600 rpm; Characteristic 2: The mixing time is 10 - 30 min; Characteristic 3: The mixing is carried out under a protective atmosphere condition.

7. The preparation method according to claim 5, characterized in that, the sintering of the Prussian blue analogue and the coating material comprises at least one of the following characteristics: Characteristic 1: The sintering temperature is 100 - 200 °C; Characteristic 2: The sintering time is 6 - 10 h; Characteristic 3: The sintering is carried out under a protective atmosphere condition.

8. The preparation method according to claim 5, characterized in that, the preparation of the Prussian blue analogue comprises: mixing a first solution, a second solution and a third solution; wherein, the first solution contains a divalent iron salt and a reducing agent, the second solution contains a divalent cobalt salt and a reducing agent, and the third solution contains a sodium salt.

9. The preparation method according to claim 8, characterized in that, the first solution comprises sodium ferrocyanide decahydrate; and / or, the second solution comprises at least one of cobalt chloride and cobalt sulfate; and / or, the third solution comprises at least one of sodium chloride and sodium sulfate; and / or, the reducing agent comprises ascorbic acid.

10. The preparation method according to claim 8, characterized in that, the mixing of the first solution, the second solution and the third solution comprises at least one of the following characteristics: Feature 1: Drop the first solution and the second solution into the third solution; Feature 2: The mixing is carried out under a protective atmosphere condition.

11. According to the preparation method described in claim 10, wherein, the dropping rate is 1 - 30 mL / h.

12. According to the preparation method described in claim 8, wherein, it further includes solid-liquid separation and drying of the obtained suspension after mixing.

13. A battery, wherein, the positive electrode material of the battery is the Prussian blue analogue positive electrode material described in any one of claims 1 - 4.

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