A method for preparing a porous, sieved, catalyzed positive electrode material for low temperature batteries

Abstract

The application discloses a preparation method of a porous sieving catalytic positive electrode material for a low-temperature battery. The carbon material carrier is continuously washed with ethanol under ultrasonic treatment for 10-30 min, then washed with deionized water, and then immersed in concentrated nitric acid, and washed with deionized water after being taken out. The catalyst and urea are dissolved in deionized water, uniformly stirred, and then transferred into a reaction kettle, and then heated to 150-200 DEG C and kept for 7-10 h to perform hydrothermal reaction, and then the reaction liquid is cooled to room temperature, and then the treated carbon material carrier is immersed in the reaction liquid. The immersed carbon material carrier is washed with ethanol, vacuum dried at 40-60 DEG C for 5-8 h, and then annealed to obtain the porous sieving catalytic positive electrode material. The method combines porous sieving and catalytic desolvation, can significantly improve the ion conduction capacity of the aqueous zinc battery, optimizes the size of the hydrated ions through the porous sieving effect, inhibits the dissolution of metal ions in the positive electrode material, and thus improves the battery performance of the zinc battery.

Description

Technical Field

[0001] This invention relates to the field of battery materials, and more particularly to a method for preparing a porous sieved catalytic cathode material for low-temperature batteries. Background Technology

[0002] Lithium-ion batteries suffer from drawbacks such as the flammability of organic electrolytes, scarcity of lithium resources, and high costs, limiting their application in large-scale cryogenic energy storage scenarios. Aqueous zinc-ion batteries, with their advantages of abundant zinc reserves, safe electrolytes with no risk of combustion or explosion, high theoretical capacity, and excellent power characteristics, have become a highly promising alternative system in the cryogenic energy storage field. Recent research indicates that in aqueous zinc-ion batteries, the reaction kinetics on the positive electrode side are severely limited by the insertion / extraction process of Zn²⁺ in the positive electrode material. This manifests in the following two aspects:

[0003] On the one hand, in conventional aqueous zinc-ion battery electrolytes, Zn 2+ With [Zn(H2O)] n ] 2+ The presence of hydrated ions at the cathode interface requires overcoming a high activation energy barrier during desolvation, resulting in slow Zn²⁺ intercalation kinetics. Especially at low temperatures (≤ -10 °C), electrolyte viscosity increases significantly, ion migration resistance surges, and cathode zinc intercalation / deintercalation kinetics are severely delayed, leading to a significant decrease in battery capacity at low temperatures. Furthermore, vanadium ions in vanadium-based cathode active materials are easily dissolved and lost during charge and discharge, causing irreversible loss of the active material. At low temperatures, electrolyte solvation is enhanced, further exacerbating vanadium dissolution and rapidly shortening battery cycle life. In addition, traditional carbon materials rely solely on physical adsorption to load vanadium-based cathode active materials, resulting in weak interfacial bonding and easy stripping and detachment of the active material during cycling. Existing modification schemes only introduce porous structures or catalytic components, without synergistic effects: single porous carbon materials lack ion sieving capabilities and cannot prevent vanadium dissolution; single catalytic modification cannot improve ion diffusion channels, and catalytic sites are easily covered and deactivated by vanadium byproducts at low temperatures.

[0004] Therefore, developing a cathode material that can simultaneously achieve efficient desolvation of hydrated ions and suppress the dissolution of cathode metal ions under low-temperature conditions is key to improving the low-temperature performance of aqueous zinc-ion batteries. Summary of the Invention

[0005] To address the shortcomings of existing vanadium-based cathodes in aqueous zinc-ion batteries, such as poor low-temperature kinetics, severe vanadium ion dissolution, weak bonding between the carbon substrate and the active material, and the lack of synergistic benefits from single modification methods, this paper proposes a method for preparing cathode materials that integrates porous sieving and catalysis. Through a coupled structure of "mesoporous sieving channels + in-situ catalytic sites," this method simultaneously solves two major problems: high low-temperature desolvation energy barriers and active material dissolution.

[0006] A method for preparing a porous sieved catalytic cathode material for low-temperature batteries includes the following steps:

[0007] (1) Carbon carrier modification: The carbon material carrier is continuously washed with ethanol for 10-30 min under ultrasonic treatment, cleaned with deionized water, and then immersed in concentrated nitric acid for etching. After taking it out, it is washed with deionized water again until neutral for later use.

[0008] (2) Preparation and impregnation of hydrothermal composite precursor solution: Vanadium-based positive electrode active material, porous sieve precursor, catalyst and urea are dissolved together in deionized water, stirred evenly and then transferred to a polytetrafluoroethylene-lined reactor. The mixture is kept at 150-200 ℃ for 7-10 h and then naturally cooled to room temperature to obtain composite precursor solution. The carbon material carrier modified in step (1) is completely immersed in the composite precursor solution to complete the loading.

[0009] (3) Post-processing and molding: The impregnated carbon material carrier is washed with ethanol, then vacuum dried at 40 ℃~60 ℃ for 5~8 h, and annealed to obtain the porous sieve catalytic cathode material for low temperature batteries.

[0010] Furthermore, the carbon material carrier is carbon fiber cloth, or paper or cloth prepared from graphene powder or carbon nanotube powder.

[0011] Furthermore, the porous sieving precursor is one or more of mesoporous silica, ZIF-8 molecular sieve, and MIL-53 MOF; after annealing, the porous sieving precursor forms 2-10 nm mesoporous sieving channels for selective permeation of hydrated Zn. 2+ (Diameter 0.86 nm), and retains polyvanadate, vanadium oxide clusters, and sol aggregates (diameter > 10 nm). The mass ratio of the catalyst to the porous sieve precursor is 0.01~0.5:1.

[0012] Furthermore, the vanadium-based positive electrode active material is selected from any one of V2O5, VO, V2O3, and VO2; the catalyst is selected from one or more of monatomic metals, metal sulfides, and metal nitrides. The mass ratio of the vanadium-based positive electrode active material to the porous sieve precursor is 1:2~3, and the mass ratio of the vanadium-based positive electrode active material to urea is 1:2~3.

[0013] Furthermore, the annealing process is as follows: anneal at 200℃~320℃ for 40~80 min in an air atmosphere with a heating rate of 1~5℃ / min.

[0014] The present invention has the following beneficial effects:

[0015] 1. This invention employs a combination of porous sieving and catalytic desolvation, which significantly improves the ion conduction capacity of aqueous zinc-ion batteries. At the same time, the porous sieving optimizes the size of ions on the positive electrode side and inhibits the dissolution of metal ions in the positive electrode active material, thereby improving the performance of aqueous zinc-ion batteries.

[0016] 2. In this invention, the carbon material support serves as the catalyst support. After surface treatment with concentrated nitric acid, a large number of pores are generated, allowing the catalyst to be uniformly dispersed. This invention introduces oxygen-containing polar groups onto the surface of the carbon material support through etching with concentrated nitric acid. The vanadium-based, sieved, and catalytic components are firmly attached to the carbon substrate through chemical bonds, preventing active material peeling and shedding during charge-discharge cycles, thus extending battery life.

[0017] 3. The annealing treatment in this invention is crucial for forming a porous positive electrode active material. During the annealing process, urea releases gases such as ammonia, carbon dioxide, and water vapor, which help form a uniform pore structure. The entire process involves only two thermal processing steps: hydrothermal and low-temperature annealing. It eliminates the need for high-temperature sintering and expensive organic solvents, and the raw materials are inexpensive and readily available, making it suitable for the mass production needs of energy storage electrodes. Attached Figure Description

[0018] Figure 1 The CV curve is shown for the CR2032 button cell prepared from the positive electrode active material obtained in Example 1.

[0019] Figure 2 The graph shows the cycle coulombic efficiency and specific capacity of the CR2032 coin cell prepared from the positive electrode active material obtained in Example 1 at 1C.

[0020] Figure 3 The specific capacity diagram of the CR2032 button battery prepared from the positive electrode active material obtained in Example 1 at -10°C is shown. Detailed Implementation

[0021] The present invention will be described below with reference to examples. These examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0022] Example 1

[0023] A method for preparing a porous sieved catalytic cathode material for low-temperature batteries includes the following steps:

[0024] (1) Carbon carrier modification: Take carbon fiber cloth, ultrasonically wash it with anhydrous ethanol for 10 min, rinse it with deionized water, soak it in concentrated nitric acid for 12 h for etching modification, wash it with water until neutral, and then soak it in deionized water for later use.

[0025] (2) Preparation and impregnation of hydrothermal composite precursor solution: Take 0.5 g V2O5, 1.25 g ZIF-8 sieved precursor, 0.0625 g Co single-atom catalyst and 1.25 g urea and dissolve them in deionized water. Stir for 3 h to mix evenly. Transfer to a polytetrafluoroethylene-lined reactor and keep at 150 ℃ for 10 h. Let it cool naturally to room temperature. Immerse the modified carbon fiber cloth in the precursor solution for 4 h.

[0026] (3) Post-processing and molding: Wash with ethanol 4 times, vacuum dry at 40 ℃ for 8 h; heat up to 200 ℃ in a tube furnace under air atmosphere at 2 ℃ / min, and anneal at a constant temperature for 60 min to obtain the target cathode material.

[0027] Example 2

[0028] A method for preparing a porous sieved catalytic cathode material for low-temperature batteries includes the following steps:

[0029] (1) Carbon carrier modification: The cloth prepared by carbon nanotube powder was ultrasonically washed with ethanol for 20 min, cleaned with deionized water, etched with concentrated nitric acid for 12 h, and then washed with water to neutralize for later use.

[0030] (2) Preparation of precursor solution: 0.5 g VO, 1 g mesoporous silica, 0.02 g MoS2 catalyst and 1 g urea were dissolved in deionized water and stirred for 3 h; hydrothermal heat treatment at 175 ℃ for 8 h, and then impregnated with carbon nanotube cloth for 3 h after cooling.

[0031] (3) Post-treatment: Wash with ethanol, vacuum dry at 50 ℃ for 5 h; heat to 250 ℃ with air at 2 ℃ / min, hold for 60 min and anneal to form.

[0032] Example 3

[0033] A method for preparing a porous sieved catalytic cathode material for low-temperature batteries includes the following steps:

[0034] (1) Carbon carrier modification: Paper prepared from graphene powder was ultrasonically washed with ethanol for 30 min, etched with concentrated nitric acid for 12 h, and then washed with water to neutralize.

[0035] (2) Preparation of precursor solution: 0.5 g V2O3, 1.5 g MIL-53, 0.15 g VN catalyst, and 1.5 g urea were stirred and dissolved; hydrothermal treatment was carried out at 180 ℃ for 9 h, followed by cooling and impregnation with carbon cloth for 5 h.

[0036] (3) Post-treatment: vacuum drying at 60 ℃ for 8 h, and air annealing at 300 ℃ for 60 min.

[0037] Example 4

[0038] A method for preparing a porous sieved catalytic cathode material for low-temperature batteries includes the following steps:

[0039] (1) Carbon carrier modification: carbon fiber cloth was ultrasonically washed with ethanol for 30 min, etched with concentrated nitric acid for 12 h, and then washed with water to neutralize.

[0040] (2) Preparation of precursor solution: 0.5 g VO2, 1.25 g ZIF-8, 0.2 g NiS catalyst, 1.25 g urea; hydrothermal treatment at 200 ℃ for 10 h, followed by cooling and impregnation with carbon cloth for 6 h;

[0041] (3) Post-treatment: vacuum drying at 60 ℃ for 8 h, and air annealing at 320 ℃ for 60 min.

[0042] The positive electrode active materials obtained in Examples 1-4 were used as binderless working electrodes for rechargeable aqueous zinc-ion batteries. CR2032 coin cells were assembled in ambient air using a working electrode, a glass fiber separator, a 2 M LiTFSI + 1 M Zn(CF3SO3)2 aqueous electrolyte (approximately 100 μL of electrolyte per coin cell), and a zinc foil counter electrode. Quasi-solid-state batteries were assembled by sandwiching a PVA / WIS hydrogel electrolyte between a porous V2O5 / C cathode and a Zn foil. Testing was performed on a LANHECT2001A battery testing system at 0.2–1.6 V vs. Zn. 2+ Charge / discharge measurements were performed within the voltage window of / Zn. Prior to long-term cycling testing, all electrodes underwent three cycles of electrochemical activation at 0.2 A / g, and electrochemical impedance spectroscopy (EIS) and CV curves were recorded on a CHI660E electrochemical workstation. A three-electrode cell was assembled using a 2 M LiTFSI aqueous electrolyte, a saturated Ag / AgCl reference electrode, a porous V₂O₅ / C working electrode, and a Ti box counter electrode. Except for temperature-dependent experiments on the quasi-solid-state cell, all electrochemical tests were performed at 28 °C.

[0043] Figure 1 The figure shows the CV performance of the CR2032 coin cell prepared from the cathode material obtained in Example 1. As can be seen from the figure, the redox peaks appearing in the curve are attributed to the gradual Li... + / Zn 2+ Co-intercalation / extraction behavior. The highly overlapping CV curves (except for the initial reduction process) demonstrate the excellent redox reversibility of the cathode.

[0044] Figure 2The graph shows the CR2032 coin cell prepared from the cathode material obtained in Example 1, and its cycle coulombic efficiency and specific capacity at 1C. As can be seen from the curves in the graph, the battery exhibits excellent cycle stability, with a high capacity retention rate after 1000 cycles, and also shows a high coulombic efficiency.

[0045] Figure 3 The graph shows the specific capacity of the CR2032 button cell prepared from the cathode material obtained in Example 1 at -10 °C. As can be seen from the curve, the battery can still maintain a low specific capacity at -10 °C, showing excellent low temperature tolerance. This is because even at -10 °C, it indicates that the WIS electrolyte will not freeze at this temperature, and it still has excellent performance at low temperatures.

[0046] The above are preferred embodiments and comparative examples of the present invention, and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, fine-tuning of process parameters, simple substitution of materials, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a porous sieve catalytic cathode material for low-temperature batteries, characterized in that, Includes the following steps: (1) Carbon carrier modification: The carbon material carrier is continuously washed with ethanol for 10-30 min under ultrasonic treatment, cleaned with deionized water, and then immersed in concentrated nitric acid for etching. After taking it out, it is washed with deionized water again until neutral for later use. (2) Preparation and impregnation of hydrothermal composite precursor solution: Vanadium-based positive electrode active material, porous sieve precursor, catalyst and urea are dissolved together in deionized water, stirred evenly and then transferred to a polytetrafluoroethylene-lined reactor. The mixture is kept at 150-200 ℃ for 7-10 h and then naturally cooled to room temperature to obtain composite precursor solution. The carbon material carrier modified in step (1) is completely immersed in the composite precursor solution to complete the loading. (3) Post-processing and molding: The impregnated carbon material carrier is washed with ethanol, then vacuum dried at 40 ℃~60 ℃ for 5~8 h, and annealed to obtain the porous sieve catalytic cathode material for low temperature batteries.

2. The method according to claim 1, characterized in that, The carbon material carrier is carbon fiber cloth, or paper or cloth prepared from graphene powder or carbon nanotube powder.

3. The method according to claim 1, characterized in that, The porous sieving precursor is one or more of mesoporous silica, ZIF-8 molecular sieve, and MIL-53 MOF; after annealing, the porous sieving precursor forms 2-10 nm mesoporous sieving channels for selective permeation of hydrated Zn. 2+ It retains polyvanadate, vanadium oxide clusters, and sol aggregates; the mass ratio of the catalyst to the porous sieve precursor is 0.01~0.5:

1.

4. The method according to claim 1, characterized in that, The vanadium-based positive electrode active material is selected from any one of V2O5, VO, V2O3, and VO2; the catalyst is selected from one or more of monatomic metals, metal sulfides, and metal nitrides; the mass ratio of the vanadium-based positive electrode active material to the porous sieve precursor is 1:2~3, and the mass ratio of the vanadium-based positive electrode active material to urea is 1:2~3.

5. The method according to claim 1, characterized in that, The annealing process is as follows: heat to 200 ℃~320 ℃ in air at a heating rate of 1~5 ℃ / min, and anneal for 40~80 min.

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