Aqueous battery cathode material and preparation method thereof

Abstract

The application discloses a water-based battery positive electrode material, adopts Na4Mn2(PO4)2SiO4 as a positive electrode active substance, and forms Na4Mn2(PO4)2SiO4 carbon composite material by compounding Na4Mn2(PO4)2SiO4 and carbon material as the positive electrode material; the Na4Mn2(PO4)2SiO4 is a polyanion material, has a NASICON structure, and the first Na4Mn2(PO4)2SiO4 carbon composite material can guarantee that the oxidation-reduction potential is in the electrochemical window of the battery and improve the electrochemical performance of the battery. The application further discloses a preparation method of the water-based battery positive electrode material, the active material is compounded with organic / inorganic carbon material by a solid-phase synthesis method and one step or multiple steps to form a multi-stage carbon composite material, the conductivity of the material is improved, and the electrochemical performance of the battery is improved; the preparation process is clear, the raw material price is low, and in general, the preparation method is easy to realize scale production and has great application potential.

Description

Technical Field

[0001] This invention relates to the field of secondary energy storage batteries, specifically to an aqueous battery cathode material and its preparation method. Background Technology

[0002] Amid the global trend towards achieving carbon neutrality, the utilization of new energy sources such as solar, wind, and tidal power poses significant challenges to large-scale energy storage systems. In these systems, batteries, especially long-life, low-cost rechargeable batteries, play a crucial role.

[0003] Sodium-ion batteries have garnered significant attention and popularity due to their high specific capacity, long cycle life, and wide operating temperature range. Aqueous sodium-ion batteries, in particular, stand out for their green and safe performance. Among existing aqueous sodium-ion battery cathode material systems, NASICON polyanionic materials exhibit excellent electrochemical stability due to their unique three-dimensional structure. To achieve a long cycle life, 1) the charge / discharge voltage of the polyanionic material must be compatible with the electrochemical window of the aqueous battery; 2) the material needs to possess high conductivity to match the high conductivity of the aqueous electrolyte, thereby reducing the occurrence of side reactions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a cathode material for aqueous batteries. For the first time, a Na4Mn2(PO4)2SiO4 carbon composite material with a polyanionic NASICON structure is combined with carbon materials to form Na4Mn2(PO4)2SiO4 as the cathode material for aqueous batteries. This ensures that the redox potential remains within the electrochemical window of the battery, thereby improving the battery's electrochemical performance.

[0005] Another objective of this invention is to provide a method for preparing an aqueous battery cathode material. This method has a clear preparation process, uses inexpensive raw materials, and is generally easy to scale up for production, thus having great application potential.

[0006] One technical solution to achieve the above objective is: a positive electrode material for an aqueous battery, which uses Na4Mn2(PO4)2SiO4 as the positive electrode active material, and combines Na4Mn2(PO4)2SiO4 with carbon materials to form Na4Mn2(PO4)2SiO4 carbon composite material as the positive electrode material; wherein Na4Mn2(PO4)2SiO4 is a polyanionic material with a NASICON structure.

[0007] In the above-mentioned aqueous battery cathode material, when Na4Mn2(PO4)2SiO4 is applied to an aqueous ion secondary battery, the cathode is a composite of Na4Mn2(PO4)2SiO4 carbon composite material, binder and conductive carbon, and the anode is a composite of NASICON structured titanium phosphate oxide anode material, binder and conductive carbon.

[0008] This invention also provides a method for preparing the above-mentioned aqueous battery cathode material, which uses a one-step or multi-step method to combine Na4Mn2(PO4)2SiO4 with carbon materials to form a Na4Mn2(PO4)2SiO4 carbon composite material, wherein:

[0009] The one-step method involves mixing Na, Mn, P, Si, and carbon source materials in a specific ratio, drying them to obtain a precursor powder, heating it to 550–850°C in an atmosphere furnace and holding it at that temperature for 4–24 hours at a heating rate of 1–5°C / min, and then cooling and pulverizing it to obtain the Na4Mn2(PO4)2SiO4 carbon composite material.

[0010] The multi-step method involves first mixing Na, Mn, P, and Si sources in a specific ratio, drying the mixture to obtain a precursor powder, heating it to 550–850°C in an atmosphere furnace and holding it at that temperature for 4–24 hours, then cooling and pulverizing it to obtain a preliminary product. Next, the preliminary product is mixed uniformly with a carbon source material in a specific ratio, dried to obtain a powder, heated to 550–850°C in an atmosphere furnace and held at that temperature for 4–24 hours, then cooled and pulverized to obtain the Na4Mn2(PO4)2SiO4 carbon composite material.

[0011] In the above-mentioned method for preparing the cathode material of an aqueous battery, the mass ratio of Na source, Mn source, P source and Si source materials is (3.6~4.4):(1.8~2.2):(1.8~2.2):(0.9~1.1), and the total mass ratio of Na source, Mn source, P source and Si source materials to the mass ratio of carbon source material is (0.7~0.99):(0.01~0.3).

[0012] In the above-mentioned method for preparing the positive electrode material of an aqueous battery, the Na source material is one or more of Na2CO3, NaOH, Na2SO4, and NaH2PO4; the Mn source material is one or more of MnO, Mn2O3, Mn3O4, and MnCO3; the P source material is one or more of H3PO4, NH4H2PO4, (NH4)2HPO4, and P2O5; and the Si source material is one or more of SiO2 and Na2SiO3.

[0013] The above-mentioned method for preparing aqueous battery cathode materials includes, wherein the uniform mixing method is one or more of dry ball milling, wet ball milling, and high-speed dispersion mixing; and the drying method is one or more of fluidized bed drying, spray drying, and disc drying.

[0014] In the above-mentioned method for preparing the positive electrode material of aqueous batteries, the atmosphere in the atmosphere furnace is nitrogen and / or argon.

[0015] In the above-mentioned method for preparing the positive electrode material of an aqueous battery, the cooling method is active cooling and / or natural cooling; the pulverization method is one or more of mechanical pulverization, air jet milling, and disc milling.

[0016] The technical solution of the aqueous battery cathode material and its preparation method of the present invention is the first to combine Na4Mn2(PO4)2SiO4 with carbon materials to form Na4Mn2(PO4)2SiO4 carbon composite material as aqueous battery cathode material. This can ensure that the redox potential is within the electrochemical window of the battery, improve the electrochemical performance of the battery, and the preparation process is clear and the raw materials are inexpensive. In general, the preparation method is easy to achieve large-scale production and has great application potential. Attached Figure Description

[0017] Figure 1 The image shown is an electron microscope image of the Na4Mn2(PO4)2SiO4 carbon composite material from Example 1.

[0018] Figure 2 The first charge-discharge curve of the battery made of Na4Mn2(PO4)2SiO4 carbon composite material in Example 1 is shown.

[0019] Figure 3 The electrochemical cycling curve of the battery made from the Na4Mn2(PO4)2SiO4 carbon composite material in Example 2 is shown. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, its specific embodiments are described in detail below with reference to the accompanying drawings:

[0021] Example 1

[0022] Please see Figure 1 and Figure 2Example 1 of the present invention describes a Na4Mn2(PO4)2SiO4 carbon composite material prepared using a one-step method. 0.4 mol of sodium carbonate, 0.2 mol of manganese trioxide, 0.4 mol of ammonium dihydrogen phosphate, 0.2 mol of silicon dioxide, 4 g of acetylene black, 8 g of sucrose, and 200 g of deionized water were weighed into a ball mill jar and ball-milled for 2 hours using a planetary ball mill. The slurry was then spray-dried using a centrifugal spray dryer to obtain a precursor powder. The precursor was transferred to a tube furnace under a nitrogen atmosphere and heated to 700°C at a rate of 3°C / min, held at that temperature for 12 hours, and allowed to cool naturally to room temperature. After grinding, the Na4Mn2(PO4)2SiO4 carbon composite material was obtained. Its electron micrograph is shown below. Figure 1 .

[0023] A slurry was prepared by ball milling 80g of Na4Mn2(PO4)2SiO4 carbon composite material, 10g of conductive carbon black, and 10g of aqueous binder for 4 hours. The slurry was coated onto a stainless steel foil and dried in a forced-air drying oven at 80℃ for 16 hours to obtain the positive electrode. A negative electrode was prepared by ball milling 80g of commercially available NaTi2(PO4)3, 10g of conductive carbon black, and 10g of aqueous binder for 2 hours. The slurry was coated onto a stainless steel foil and dried in a forced-air drying oven at 80℃ for 12 hours.

[0024] A non-woven fabric separator was used as the diaphragm, and an aqueous solution containing 1.5 mol sodium sulfate was used as the electrolyte. A 2032 button cell was assembled, and electrochemical tests were conducted after 10 hours of standing. The first cycle curve is shown below. Figure 2 The battery exhibits a discharge specific capacity of 85 mAh / g, with charge and discharge voltages of 1.7 V and 1.5 V, respectively. The test results demonstrate that the Na4Mn2(PO4)2SiO4 carbon composite material improves the material's conductivity and enhances the battery's electrochemical performance.

[0025] Example 2

[0026] Please see Figure 3 In Example 2 of the present invention, the Na4Mn2(PO4)2SiO4 carbon composite material was prepared by a one-step method. 0.4 mol of sodium hydroxide, 0.4 mol of manganese carbonate, 0.4 mol of phosphoric acid, 0.2 mol of sodium silicate, 15 g of citric acid and 250 g of deionized water were weighed into a ball mill jar and ball-milled for 3 hours using a planetary ball mill. The slurry was then spray-dried using a centrifugal spray dryer to obtain precursor powder. The precursor was transferred to a muffle furnace and heated to 720°C at a heating rate of 5°C / min and held at that temperature for 5 hours. After naturally cooling to room temperature, the Na4Mn2(PO4)2SiO4 carbon composite material was obtained by grinding.

[0027] A slurry was prepared by ball milling 45g of Na4Mn2(PO4)2SiO4 carbon composite material, 2.5g of conductive carbon black, and 2.5g of aqueous binder for 4 hours. The slurry was coated onto a stainless steel foil and dried in a forced-air drying oven at 80℃ for 12 hours to obtain the positive electrode. A negative electrode was prepared by ball milling 45g of commercially available NaTi2(PO4)3, 2.5g of conductive carbon black, and 2.5g of aqueous binder for 3 hours. The slurry was coated onto a stainless steel foil and dried in a forced-air drying oven at 80℃ for 12 hours.

[0028] A non-woven fabric was used as the separator, and a mixed solution of water and ethylene glycol containing 1.2 mol sodium sulfate (water / ethylene glycol mass ratio of 1) was used as the electrolyte. A 2032 button cell was assembled, and electrochemical tests were performed after 8 hours of standing. The 0.1C electrochemical cycling curve is shown below. Figure 3 The test results show that the Na4Mn2(PO4)2SiO4 carbon composite material improves the conductivity of the material and enhances the electrochemical performance of the battery.

[0029] The design concept of the aqueous battery cathode material of the present invention is as follows:

[0030] (1) Conventional Mn 2+ / Mn 3+ The conversion between them, due to Mn 3+ The disproportionation effect of Mn leads to severe degradation of the material; 3+ / Mn 4+ The redox potential between them is too high, exceeding the decomposition voltage of water;

[0031] (2) By adding the less electronegative "SiO4", the Mn content is reduced. 3+ / Mn 4+ By adjusting the redox potential from 1.3-1.5V to 1.1-1.3V (VS SHE) and using a suitable electrolyte, the redox potential can be kept within the electrochemical window of the battery.

[0032] (3) By solid-state synthesis, the active material Na4Mn2(PO4)2SiO4 is combined with organic / inorganic carbon materials in one step or multiple steps to form a multi-level carbon composite material, which improves the conductivity of the material and enhances the electrochemical performance of the battery.

[0033] In summary, the aqueous battery cathode material and its preparation method of the present invention, for the first time, combine Na4Mn2(PO4)2SiO4 with carbon materials to form Na4Mn2(PO4)2SiO4 carbon composite material as the cathode material of aqueous batteries. This method can ensure that the redox potential is within the electrochemical window of the battery, thereby improving the electrochemical performance of the battery. Moreover, the preparation process is clear, the raw materials are inexpensive, and overall, the preparation method is easy to scale up and has great application potential.

[0034] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A cathode material for an aqueous battery, characterized in that, Na4Mn2(PO4)2SiO4 is used as the positive electrode active material. Na4Mn2(PO4)2SiO4 is combined with carbon materials to form Na4Mn2(PO4)2SiO4 carbon composite material as the positive electrode material. Na4Mn2(PO4)2SiO4 is a polyanionic material with a NASICON structure.

2. The aqueous battery cathode material as described in claim 1, characterized in that, When Na4Mn2(PO4)2SiO4 is used in an aqueous ion-ion secondary battery, the positive electrode is a composite of Na4Mn2(PO4)2SiO4 carbon composite material, binder and conductive carbon, and the negative electrode is a composite of titanium phosphate oxide negative electrode material with NASICON structure, binder and conductive carbon.

3. A method for preparing the aqueous battery cathode material as described in claim 1, characterized in that, Na4Mn2(PO4)2SiO4 is composited with carbon materials using a one-step or multi-step method to form Na4Mn2(PO4)2SiO4 carbon composite materials, wherein: The one-step method involves mixing Na, Mn, P, Si, and carbon source materials in a specific ratio, drying them to obtain a precursor powder, heating it to 550–850°C in an atmosphere furnace and holding it at that temperature for 4–24 hours at a heating rate of 1–5°C / min, and then cooling and pulverizing it to obtain the Na4Mn2(PO4)2SiO4 carbon composite material. The multi-step method involves first mixing Na, Mn, P, and Si sources in a specific ratio, drying the mixture to obtain a precursor powder, heating it to 550–850°C in an atmosphere furnace and holding it at that temperature for 4–24 hours, then cooling and pulverizing it to obtain a preliminary product. Next, the preliminary product is mixed uniformly with a carbon source material in a specific ratio, dried to obtain a powder, heated to 550–850°C in an atmosphere furnace and held at that temperature for 4–24 hours, then cooled and pulverized to obtain the Na4Mn2(PO4)2SiO4 carbon composite material.

4. The method for preparing the aqueous battery cathode material as described in claim 3, characterized in that, The mass ratio of Na-source, Mn-source, P-source and Si-source materials is (3.6-4.4):(1.8-2.2):(1.8-2.2):(0.9-1.1), and the total mass ratio of Na-source, Mn-source, P-source and Si-source materials to the mass ratio of carbon source materials is (0.7-0.99):(0.01-0.3).

5. The method for preparing the aqueous battery cathode material as described in claim 3 or 4, characterized in that, The Na source material is one or more of Na2CO3, NaOH, Na2SO4, and NaH2PO4; the Mn source material is one or more of MnO, Mn2O3, Mn3O4, and MnCO3; the P source material is one or more of H3PO4, NH4H2PO4, (NH4)2HPO4, and P2O5; and the Si source material is one or more of SiO2 and Na2SiO3.

6. The method for preparing the aqueous battery cathode material as described in claim 3 or 4, characterized in that, The mixing method is one or more of dry ball milling, wet ball milling, and high-speed dispersion mixing; the drying method is one or more of fluidized bed drying, spray drying, and disc drying.

7. The method for preparing the aqueous battery cathode material as described in claim 3 or 4, characterized in that, The atmosphere in the atmosphere kiln is nitrogen and / or argon.

8. The method for preparing the aqueous battery cathode material as described in claim 3 or 4, characterized in that, The cooling method is active cooling and / or natural cooling; the pulverizing method is one or more of mechanical pulverization, air jet mill pulverization and disc pulverization.

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