CN114497827B - Manufacturing method of solid-state potassium air battery - Google Patents

Abstract

The invention discloses a new solid-state potassium air battery manufacturing method, which relates to the technical field of battery manufacturing. The steps of the method are as follows: Step 1: Ball-mill and dry the hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal; Step 2: Prepare a PVA aqueous solution, add medium PVA to the K ₂ Fe ₄ O ₇ powder, dilute with water, and heat until completely dry; Step 3: Sieve the PVA-containing K ₂ Fe ₄ O ₇ and cold-press into tablets; Step 4: Press the solid electrolyte sheet and the hydrophilic carbon cloth together and place them in a constant temperature and humidity box for balance; Step 5: Combine the metal potassium, the double-layer GF/D separator containing a trace amount of potassium ion electrolyte, and the solid electrolyte after balancing the humidity. The sheets, hydrophilic carbon cloth and nickel foam are stacked and packaged between the positive and negative electrode shells. The invention provides a method for increasing the intrinsic potassium ion conductivity and grain boundary conductivity of K ₂ Fe ₄ O ₇ and improving the interface ion transmission of the battery. The method is easy to operate.

Description

A method for manufacturing a solid-state potassium-air battery

Technical field

The invention relates to the technical field of battery manufacturing, specifically a method for manufacturing a solid-state potassium-air battery.

Background technique

Among all known battery systems, lithium-oxygen (Li-O ₂ ) batteries have become the long-term successor of lithium-ion batteries because they have the highest theoretical energy density. However, their practical applications are limited by low energy efficiency, slow kinetics, and oxygen reduction and evolution reaction (ORR/OER) catalysts.

Potassium metal is the lightest alkali metal cation that forms the thermodynamically stable superoxide (KO ₂ ) product. This enables potassium oxygen ( _KO2 ) batteries to operate via the simple one-electron redox process of _O2 / _KO2 . This system provides a solution to the persistent kinetic challenge of ORR/OER in air batteries without the use of any electrocatalyst. However, this system is extremely immature in the field of metal-air batteries. The unstable decomposition of the electrolyte and the irreversible corrosion of the negative electrode are a major bottleneck that limits the improvement of its battery performance. In addition, assembling solid-state batteries can also avoid combustion caused by short circuits and leakage. , explosion and other dangerous accidents. Therefore, there is an urgent need for a potassium ion solid electrolyte that can be used in this battery system to solve the problems caused by liquid electrolyte. Unfortunately, due to the scarcity of currently available room-temperature potassium ion conductors, there have been no reports on solid-state potassium-air batteries.

K ₂ Fe ₄ O ₇ is one of the rare potassium ion solid electrolytes currently available. The material has a three-dimensional pore structure and is a potential electrolyte material. However, development is currently at a cognitively immature stage. This material currently cannot be sintered densely, resulting in excessive grain boundary resistance and incomplete understanding of the ion transport state in bulk resistance. Developing such solid-state electrolytes and applying them to new solid-state battery systems is currently a difficult problem.

The existing K ₂ Fe ₄ O ₇ solid-state battery only consists of a simple stack of components to form a button battery. When used in ion batteries, the interface contact is not tight, and ion transport at the interface between the electrolyte and the positive electrode is difficult. The battery capacity is low and has certain limitations.

Contents of the invention

The object of the present invention is to provide a solid-state potassium-air battery manufacturing method to solve the problems in the background technology.

In order to achieve the above objects, the present invention provides the following technical solutions:

A method for making a solid-state potassium-air battery. The crystal structure is changed by introducing water to increase the ionic conductivity, and the solid-state potassium-oxygen battery is made into a solid-state potassium-oxygen battery. The specific operation steps are as follows: Step 1: Hydrothermally synthesize K ₂ Fe ₄ O ₇ single crystal is ball milled and dried; Step 2: Configure a PVA aqueous solution with a concentration of 1% or 5%, add the prepared PVA to the K2Fe4O7 powder, dilute with water, stir, and heat until completely dry; Step 3: The obtained PVA-containing K ₂ Fe ₄ O ₇ is sieved and granulated, divided into equal parts and cold-pressed into tablets to obtain solid electrolyte tablets; Step 4: Slightly press the solid electrolyte tablets and hydrophilic carbon cloth and place them in a closed constant temperature Balance different humidity in a constant humidity box, and the process lasts for more than 12 hours to obtain the solid electrolyte sheet and hydrophilic carbon cloth after balanced humidity; Step 5: Combine the metal potassium and the double-layer GF/D separator containing trace amounts of potassium ion electrolyte , the solid electrolyte sheet, hydrophilic carbon cloth and nickel foam after balancing the humidity are stacked and sealed between the positive and negative electrode shells to obtain a solid potassium air battery, in which the positive electrode is the pole containing holes.

On the basis of the above technical solutions, the present invention also provides the following optional technical solutions:

In an optional solution: the amount of PVA that needs to be added to the aqueous solution in step 2 is 1% to 5% of the amount of K ₂ Fe ₄ O ₇ .

In an optional solution: the stirring in step 2 is performed at a rotation speed of 100 to 300 r/min.

In an optional solution: the sieving mesh number for sieving and granulation in step 3 is 30 to 100.

In an optional solution: in step 4, when the solid electrolyte sheet and the hydrophilic carbon cloth are balanced in a constant temperature and humidity chamber, the temperature is 20°C to 30°C and the humidity is 50% to 80%.

In an optional solution: the double-layer electrolyte containing trace amounts of potassium ions has a concentration of 0.5 to 1 mol/L and a volume of 80 to 150 μL.

Compared with the existing technology, the beneficial effects of the present invention are as follows:

1. Based on the original process of pressing into sheets to make batteries, water was introduced. After the water was introduced, the original crystal structure was changed. The potassium ions in the structure were rapidly moved by the introduced protons and changed the original conduction. method, the intrinsic potassium ion conductivity has been greatly improved, from the original 10 ^-10 s cm ^-1 to approximately 10 ^-3 ~ 10 ^-5 s cm ^-1 . The pure potassium ion diffusion coefficient has been greatly improved. The order of magnitude increased from 10 ^-15 m ² s ^-1 to 10 ^-9 m ² s ^-1 , which meets the application requirements; potassium ion precipitates fill the grain boundaries, which also greatly increases the conductivity of the grain boundaries;

2. During the solid-state battery assembly process, the positive electrode becomes a hydrophilic carbon cloth, which is pressed together with the water-containing solid electrolyte, and the interface is connected by a small amount of potassium ion aqueous solution, so that the ion transport at the three-phase interface is smooth.

Description of the drawings

Figure 1 shows the water absorption characteristics of the solid electrolyte prepared in the present invention.

Figure 2 shows the structural changes before and after water absorption of the solid electrolyte prepared in the present invention.

Figure 3 shows the changes in the intrinsic ion transport state of the present invention.

Figure 4 shows the ion diffusion coefficient of the solid electrolyte prepared in the present invention. In the figure, D is the diffusion coefficient, T is the temperature, and Ea is the ion transport activation energy.

Figure 5 shows the overall conductivity change before and after K ₂ Fe ₄ O ₇ is introduced into water in the present invention.

Figure 6 shows the change in the conduction mode of ions at the grain boundary in the present invention.

Figure 7 shows the cycle of the potassium-oxygen solid-state battery of the present invention at a current density of 0.05 mA cm ^-2 .

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the drawings and examples. The examples listed in the present invention are only used to illustrate the present invention and are not intended to limit the present invention. Scope of invention. Any obvious modifications or changes may be made to the present invention without departing from the spirit and scope of the present invention.

Example 1

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: Ball-mill 0.2g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 5% PVA aqueous solution, add 0.04g PVA solution prepared in step 2 to 0.2g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 25°C and the humidity is set to 50%. The process lasts for 12 hours;

Step 5: Stack the metal potassium, the double-layer GF/D separator soaked with 100 μL of 1.0M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and the nickel foam between the positive and negative electrode shells to obtain a solid state Potassium air battery; the positive electrode is a porous positive electrode;

In step 2, stirring is performed at a rotation speed of 300 r/min.

The sieving mesh number for sieving and granulation in step 3 is 50.

Battery specs are 2025.

Example 2

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: Ball-mill 0.2g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 1% PVA aqueous solution, add 0.06g PVA solution prepared in step 2 to 0.15g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 20°C and the humidity is set to 60%. The process lasts for 12 hours;

Step 5: Stack the potassium metal, the double-layer GF/D separator soaked with 150 μL of 0.8M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and the nickel foam between the positive and negative electrode shells. The positive electrode is a hole-containing positive electrode.

In step 2, stirring is performed at a rotation speed of 100 r/min.

The sieving mesh number for sieving and granulation in step 3 is 60.

Battery specs are 2025.

Example 3

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: ball-mill 0.25g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 5% PVA aqueous solution, add 0.1g PVA solution prepared in step 2 to 0.25g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 28°C and the humidity is set to 70%. The process lasts for 12 hours;

Step 5: Stack the potassium metal, the double-layer GF/D separator soaked with 120 μL of 1.0M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and the nickel foam and package them between the positive and negative electrode shells; that is, a solid state is obtained Potassium-air battery, in which the positive electrode is a porous positive electrode.

In step 2, stirring is performed at a rotation speed of 250 r/min.

The sieving mesh number for sieving and granulation in step 3 is 70.

Battery specs are 2025.

Example 4

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: Ball-mill 0.3g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 5% PVA aqueous solution, add 0.18g PVA solution prepared in step 2 to 0.3g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 30°C and the humidity is set to 80%. The process lasts for 12 hours;

Step 5: Stack metal potassium, a double layer of GF/D separator soaked with 150 μL of 1.0M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and foam nickel between the positive and negative electrode shells to obtain a solid state Potassium air battery; the positive electrode is a porous positive electrode.

Battery specs are 2025.

In step 2, stirring is performed at a rotation speed of 150 r/min.

The sieving mesh number for sieving and granulation in step 3 is 80.

Example 5

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: ball-mill 0.18g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 5% PVA aqueous solution, add 0.18g PVA solution prepared in step 2 to 0.18g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 23°C and the humidity is set to 65%. The process lasts for 12 hours;

Step 5: Stack the metal potassium, the double-layer GF/D separator soaked with 80 μL of 1.0M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and the nickel foam between the positive and negative electrode shells to obtain a solid state Potassium air battery; the positive electrode is a porous positive electrode.

In step 2, stirring is performed at a rotation speed of 120 r/min.

The sieving mesh number for sieving and granulation in step 3 is 50.

Battery specs are 2025.

Example 6

A method for manufacturing a solid-state potassium-air battery is provided, including the following steps:

Step 1: ball-mill 0.15g of hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it;

Step 2: Prepare 5% PVA aqueous solution, add 0.09g PVA solution prepared in step 2 to 0.15g K ₂ Fe ₄ O ₇ powder, add a certain amount of water to dilute, stir, and heat until completely dry;

Step 3: Sieve the obtained PVA-containing K ₂ Fe ₄ O ₇ and then cold-press into tablets;

Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The temperature is set to 24°C and the humidity is set to 75%. The process lasts for 12 hours;

Step 5: Stack the metal potassium, the double-layer GF/D separator soaked with 90 μL of 1.0M KPF6-DEGEME electrolyte, the components after balancing humidity in step 4, and the nickel foam between the positive and negative electrode shells to obtain a solid state Potassium air battery; the positive electrode is a porous positive electrode.

In step 2, stirring is performed at a rotation speed of 180 r/min.

The sieving mesh number for sieving and granulation in step 3 is 80.

Battery specs are 2025.

See Figure 1 for water absorption

See Figure 2 for structural changes.

Changes in intrinsic ion transport state are shown in Figure 3

The intrinsic ion diffusion coefficient is significantly improved. See Figure 4. In the figure, D is the diffusion coefficient, T is the temperature, and Ea is the ion transmission activation energy.

The overall resistance (including grain boundary resistance) of K ₂ Fe ₄ O ₇ is significantly reduced after the introduction of water. The introduction of water changes the ion transport mode of ions at the grain boundaries.

The change in total conductivity before and after water is introduced is shown in Figure 5

The changes in the conduction mode of ions at the grain boundary are shown in Figure 6

The potassium-oxygen solid-state battery has better performance, with an overpotential of only 0.1V under a current density cycle of 0.05mA cm ^-2 , see Figure 7.

The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure. should be covered by the protection scope of this disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims (5)

1. A method for manufacturing a solid-state potassium-air battery, which is characterized in that the method changes the crystal structure by introducing water to improve ion conductivity, and makes it into a solid-state potassium-oxygen battery. The specific operating steps are as follows: Step 1: Ball-mill the hydrothermally synthesized K ₂ Fe ₄ O ₇ single crystal and dry it; Step 2: Prepare a PVA aqueous solution with a concentration of 1% or 5%, add the prepared PVA to the K ₂ Fe ₄ O ₇ powder, dilute with water, stir, and heat until completely dry; Step 3: Sieve and granulate the obtained PVA-containing K ₂ Fe ₄ O ₇ , divide it into equal parts and cold-press into tablets to obtain a solid electrolyte tablet; Step 4: Slightly press the solid electrolyte sheet and hydrophilic carbon cloth and place them in a closed constant temperature and humidity box to balance different humidity. The process lasts for more than 12 hours to obtain the solid electrolyte sheet and hydrophilic carbon cloth after balancing the humidity; Step 5: Stack metallic potassium, double-layer GF/D separator containing trace amounts of potassium ion electrolyte, balanced humidity solid electrolyte sheet, hydrophilic carbon cloth and nickel foam, and package them between the positive and negative electrode shells, that is A solid-state potassium-air battery is obtained, in which the positive electrode is a pole containing holes; The amount of PVA that needs to be added to the aqueous solution in step 2 is 1%-5% of the amount of K ₂ Fe ₄ O ₇ . 2. The solid-state potassium air battery manufacturing method according to claim 1, characterized in that the stirring in step 2 is performed at a rotation speed of 100-300 r/min. 3. The solid-state potassium-air battery manufacturing method according to claim 1, characterized in that the sieving mesh number of sieving and granulating in step 3 is 30-100. 4. The solid-state potassium-air battery manufacturing method according to claim 1, characterized in that in step 4, the temperature of the solid electrolyte sheet and the hydrophilic carbon cloth when balanced in a constant temperature and humidity box is 20°C to 30°C and the humidity 50% to 80%. 5. The solid-state potassium-air battery manufacturing method according to claim 4, characterized in that the double-layer electrolyte containing trace amounts of potassium ions has a concentration of 0.5-1 mol/L and a volume of 80-150 μL.