A magnesium-based aqueous primary battery system and its preparation method

Abstract

This invention relates to the field of magnesium primary battery preparation technology, and discloses a magnesium aqueous primary battery system, including a positive electrode, a negative electrode, and an electrolyte. The negative electrode is any one of magnesium metal and magnesium alloy. The positive electrode is made of a positive electrode active material, superconducting carbon, and a first-order gelatinizing agent. The electrolyte is made of magnesium bromide, a corrosion inhibitor, and a second-order gelatinizing agent. The preparation method includes the following steps: S1: preparing a positive electrode slurry; S2: preparing an electrolyte by introducing a corrosion inhibitor into the magnesium bromide electrolyte, followed by adding a second-order gelatinizing agent for gelatinization treatment to obtain a slow-release gelatinized electrolyte; S3: preparing a positive electrode steel shell; S4: assembling the battery. The technical solution of this invention not only slows down the corrosion rate of the negative electrode material and improves the utilization rate of the negative electrode material, but also solves the problems of voltage hysteresis and volume expansion during battery discharge; furthermore, it can match the reaction rates of the positive and negative electrodes.

Description

Technical Field

[0001] This invention relates to the field of magnesium primary battery preparation technology, specifically to a magnesium aqueous primary battery system and its preparation method. Background Technology

[0002] Against the backdrop of current global development, the energy shortage problem is intensifying, becoming a significant factor restricting the sustainable development of human society. Simultaneously, environmental awareness is growing, and people are placing increasingly higher demands on environmental protection in all aspects of production and daily life. Against this dual backdrop, the battery industry faces both enormous challenges and opportunities, with an increasingly urgent need for new, high-performance batteries.

[0003] Magnesium primary batteries have attracted much attention due to magnesium's relatively negative electrode potential, a characteristic that significantly improves their theoretical specific capacity, open-circuit voltage, and specific energy. Compared to ordinary zinc-manganese dry batteries, magnesium primary batteries have approximately twice the charge capacity for the same volume and exhibit good temperature adaptability, making them potentially valuable in specific applications.

[0004] However, despite the aforementioned advantages of magnesium primary batteries, they face numerous serious problems in practical applications, which greatly limit their widespread use.

[0005] Firstly, during battery discharge, the oxide film on the surface of the magnesium anode is damaged after partial discharge, the anode material loses its protection, the self-corrosion rate accelerates, the effective components decrease, the utilization rate of the anode material decreases, and the battery performance and service life are affected.

[0006] Secondly, the battery exhibits voltage lag during discharge, requiring a period of time to reach normal levels, which can affect equipment startup and operation. Furthermore, the battery expands significantly after discharge, potentially causing the casing to deform or crack, damaging the equipment and posing safety hazards due to leakage of internal battery materials.

[0007] Third, the mismatch between the positive and negative electrode reaction rates in magnesium primary batteries is a significant problem. The magnesium negative electrode is highly reactive and reacts quickly, while the positive electrode reacts slowly, resulting in low utilization of the magnesium negative electrode and severely limiting its practical application. To address this issue, researchers introduced corrosion inhibitors to alleviate negative electrode corrosion, but this introduced new problems. Due to the dense structure of the positive electrode, the electrolyte cannot fully penetrate into the interior, and the positive electrode reaction remains slow, leading to low electrochemical capacity and shortened discharge time. If only the positive electrode fabrication process is improved to create a looser structure, although the positive electrode activity will be enhanced, it will cause the negative electrode side to react rapidly, generating a large amount of gas in a short time, ultimately leading to serious consequences such as battery swelling, cracking, and instantaneous failure.

[0008] In summary, these problems with magnesium primary batteries severely hinder their development and application. Therefore, it is urgent to construct an intrinsically safe and stable magnesium-aqueous primary battery system, and new technological solutions are needed to address these challenges, promote the development of magnesium battery technology, and meet society's demand for high-performance, environmentally friendly batteries. Summary of the Invention

[0009] The present invention aims to provide a magnesium aqueous primary battery system and its preparation method to overcome the problems existing in the prior art.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a magnesium-aqueous primary battery system, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is any one of magnesium metal and magnesium alloy, the positive electrode is made of a positive electrode active material, superconducting carbon, and a first gelling agent, and the electrolyte is made of magnesium bromide, a corrosion inhibitor, and a second gelling agent.

[0011] Preferably, the corrosion inhibitor is any one or a combination of lithium fluoride, sodium fluoride, potassium fluoride and magnesium fluoride.

[0012] Preferably, the positive electrode active material is manganese dioxide.

[0013] Preferably, the first gelatinizing agent is any one or a combination of superabsorbent resin, hydroxypropyl starch, and starch-based bioplastics; the second gelatinizing agent is any one or a combination of corn starch, wheat starch, and potato starch.

[0014] This invention also provides another technical solution, a method for preparing a magnesium-aqueous primary battery system, comprising the following steps:

[0015] S1: Prepare positive electrode slurry by mixing positive electrode active material, superconducting carbon and No. 1 gelatinizing agent evenly in a certain mass ratio to obtain gelatinized positive electrode slurry;

[0016] S2: Prepare an electrolyte by introducing a corrosion inhibitor into the magnesium bromide electrolyte and then adding a second gelatinizing agent for gelatinization treatment to obtain a slow-release gelatinized electrolyte.

[0017] S3: Prepare a positive electrode steel shell, perform a perforation operation on the positive electrode steel shell, and attach a waterproof and breathable membrane at the perforation point to obtain a modified positive electrode shell.

[0018] S4: Assemble the battery by using the gelatinized positive electrode slurry prepared in S1 as the positive electrode slurry, the slow-release gelatinized electrolyte prepared in S2 as the electrolyte, magnesium metal or magnesium alloy as the negative electrode, glass fiber as the separator, and the modified positive electrode shell obtained in S3 as the positive electrode shell, and assemble them to obtain a magnesium aqueous primary battery.

[0019] Preferably, the mass ratio of the positive electrode active material, superconducting carbon, and gelatinizing agent No. 1 in S1 is 8:2:(0.3-2).

[0020] Preferably, the mass ratio of magnesium bromide, corrosion inhibitor, and gelling agent No. 2 in S2 is 10:1:(1-2).

[0021] Preferably, the concentration of the corrosion inhibitor in S2 is 0.05-0.15 mol / L.

[0022] Preferably, the aperture of the positive electrode shell in S3 is 0.1-2 mm.

[0023] Preferably, the thickness of the waterproof and breathable membrane in S3 is 20-100 μm.

[0024] The principle of this technical solution: Through extensive research and experimentation by the inventors, multiple improvement methods are integrated to solve existing problems and improve the performance of magnesium-based aqueous primary batteries. First, a second gelatinizing agent and a slow-release agent are introduced into the electrolyte, simultaneously treating the positive electrode powder material and improving the battery casing. The second gelatinizing agent and the slow-release agent in the electrolyte work synergistically with the treatment of the positive electrode powder material and the battery casing improvements, forming a coordinated control. These methods affect the battery's operation process from multiple aspects, effectively improving the mismatch between the positive and negative electrode reaction rates, avoiding performance degradation caused by reaction rate differences; alleviating volume expansion problems, preventing damage to the battery structure due to expansion; eliminating voltage hysteresis, ensuring stable power supply; and improving the utilization rate of the negative electrode material, reducing material waste. Through these improvements, the battery's electrochemical capacity and discharge time are thus enhanced.

[0025] Furthermore, both the positive electrode slurry and the electrolyte undergo double gelatinization. This double gelatinization design improves the reaction rate of the positive electrode active material, allowing it to participate more efficiently in the battery reaction. For the negative electrode, double gelatinization effectively reduces the contact between the electrolyte and the negative electrode, thereby lowering the negative electrode reaction rate. By separately adjusting the reaction rates of the positive and negative electrodes, the matching degree of the positive and negative electrode reactions is improved, optimizing the overall reaction coordination of the battery.

[0026] Furthermore, perforations are made on the positive electrode side of the battery, and a waterproof and breathable membrane is attached. During battery operation, excess hydrogen gas is generated, and the perforations provide a release channel for this hydrogen, preventing its accumulation inside the battery. Simultaneously, this treatment reduces system pressure and minimizes direct contact between the negative electrode interface and the electrolyte. These combined effects further enhance the service life of the magnesium-aqueous primary battery, ensuring stable and safe operation over extended periods.

[0027] Compared with existing technologies, this solution has the following advantages:

[0028] (1) Solve the existing negative electrode problem and improve the performance of the negative electrode: In response to the problem that the oxide film on the surface of the magnesium negative electrode is damaged during the battery discharge process, resulting in accelerated self-corrosion, reduced effective components and reduced negative electrode utilization, this solution reduces the side reaction between water and magnesium negative electrode in aqueous electrolyte by the slow release effect of fluoride corrosion inhibitor in electrolyte and the gelatinization function of No. 2 gelatinizing agent, thereby reducing negative electrode self-corrosion, improving the utilization rate of negative electrode material, and thus improving battery performance and service life.

[0029] (2) Solving the problems of voltage hysteresis and volume expansion: The corrosion inhibitor and the double gelatinization effectively improve the contact efficiency of each component of the primary battery, greatly reduce the internal resistance of the battery, effectively overcome the problem of voltage hysteresis affecting the start-up and operation of the equipment during battery discharge, and at the same time alleviate the safety hazards caused by the battery volume expansion after discharge, which may lead to shell deformation, cracking and leakage of internal battery materials, thus ensuring the safe and stable operation of the equipment.

[0030] (3) Improvement of the matching of positive and negative electrode reaction rates: This addresses the prominent issue of mismatched positive and negative electrode reaction rates in magnesium-aqueous primary batteries. Introducing a No. 1 gelatinizing agent into the positive electrode slurry reconstructs its dispersibility, creating excellent ion and electron transport channels within the positive electrode material, effectively enhancing the reaction rate of the positive electrode active material. Simultaneously, double gelatinization (in both the positive electrode slurry and the electrolyte) reduces the contact between the electrolyte and the negative electrode, lowering the negative electrode reaction rate and improving the matching degree of positive and negative electrode reactions. Furthermore, it avoids the problem of rapid reaction on the negative electrode side and the generation of large amounts of gas that could cause battery expansion and cracking due to only improving the positive electrode sheeting process, thus improving battery stability and safety. The addition of superconducting carbon enhances the conductivity of the positive electrode.

[0031] (4) Improved electrochemical performance and battery safety: By using multiple methods to optimize the matching of positive and negative electrode reaction kinetics, the generation of reaction gases is reduced, thereby improving electrochemical capacity and discharge time. The perforation process of the positive electrode steel shell can effectively release the gases generated during the primary aqueous magnesium battery reaction. The introduction of a waterproof and breathable membrane at the perforation point can prevent slurry overflow and improve the intrinsic safety of the magnesium primary battery.

[0032] (5) Process advantages: The preparation process provided in this application is simple and efficient, and the batch consistency of the products is good. It can be widely used in water-based button primary batteries and has good prospects for industrial application. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a magnesium-aqueous primary battery system according to Embodiment 1 of the present invention;

[0034] Figure 2 This is an effect diagram of the slow-release gelatinized electrolyte in Example 1 of the present invention;

[0035] Figure 3This is a constant current discharge diagram of a magnesium aqueous primary battery system in Embodiment 1 of the invention;

[0036] Figure 4 A constant current discharge diagram of a magnesium aqueous primary battery system in Comparative Example 1;

[0037] Figure 5 A constant current discharge diagram of a magnesium aqueous primary battery system in Comparative Example 2;

[0038] Figure 6 A constant current discharge diagram of a magnesium aqueous primary battery system in Comparative Example 3;

[0039] Figure 7 A constant current discharge diagram of a magnesium aqueous primary battery system in Comparative Example 4;

[0040] Figure 8 The constant current discharge diagram of a magnesium aqueous primary battery system in Comparative Example 5 is shown. Detailed Implementation

[0041] The following detailed description illustrates the specific implementation method:

[0042] Example 1

[0043] A magnesium-aqueous primary battery system includes a positive electrode, a negative electrode, and an electrolyte. The negative electrode is any one of magnesium metal and magnesium alloy. The positive electrode is made of a positive electrode active material, superconducting carbon, and a first-order gelling agent. The electrolyte is made of magnesium bromide, a corrosion inhibitor, and a second-order gelling agent.

[0044] The corrosion inhibitor is any one or a combination of lithium fluoride, sodium fluoride, potassium fluoride, and magnesium fluoride. In this embodiment, sodium fluoride is selected as the corrosion inhibitor.

[0045] The positive electrode active material is manganese dioxide;

[0046] The first gelatinizing agent is one or more of superabsorbent resin, hydroxypropyl starch, and starch-based bioplastics; in this embodiment, the first gelatinizing agent is superabsorbent resin.

[0047] The second gelatinizing agent is one or more of corn starch, wheat starch, and potato starch. In this embodiment, corn starch is selected as the second gelatinizing agent.

[0048] A method for preparing a magnesium-aqueous primary battery system includes the following steps:

[0049] S1: Preparation of positive electrode slurry: The positive electrode active material, superconducting carbon, and No. 1 gelatinizing agent are mixed evenly in a certain mass ratio to obtain a gelatinized positive electrode slurry; wherein, the mass ratio of the positive electrode active material, superconducting carbon, and No. 1 gelatinizing agent is 8:2:(0.3-2). In this embodiment, after grinding and mixing manganese dioxide and superconducting carbon evenly, it is added to a superabsorbent resin solution and stirred evenly to obtain a gelatinized positive electrode slurry. The amount of manganese dioxide used is 8g, the amount of superconducting carbon used is 2g, and the amount of superabsorbent resin used is 1g.

[0050] S2: Prepare the electrolyte by introducing a corrosion inhibitor into the magnesium bromide electrolyte, followed by adding a second gelatinizing agent for gelatinization treatment to obtain a slow-release gelatinized electrolyte; wherein the mass ratio of magnesium bromide, corrosion inhibitor, and second gelatinizing agent is 10:1:(1-2), the concentration of the corrosion inhibitor is 0.05-0.15 mol / L, and the concentration of magnesium bromide is 1 mol / L; in this embodiment, 1 mol / L magnesium bromide and 0.1 mol / L sodium fluoride are prepared separately and mixed evenly. The mixed solution of magnesium bromide and sodium fluoride is added to corn starch, stirred evenly, and heated at 80°C for 30 min to obtain the slow-release gelatinized electrolyte as shown. Figure 2 As shown, the amount of magnesium bromide used is 5g, the amount of sodium fluoride used is 0.5g, and the amount of corn starch used is 0.75g;

[0051] S3: Prepare a positive electrode steel shell, perform a drilling operation on the positive electrode steel shell, and attach a waterproof and breathable membrane at the drilling site to obtain a modified positive electrode shell; wherein, the pore diameter on the positive electrode shell is 0.1-2mm, and the thickness of the waterproof and breathable membrane is 20-100μm; in this embodiment, a 1mm hole is drilled in the center of the positive electrode shell, and the surface of the drilling site is heat-treated, and a waterproof and breathable membrane with a thickness of 30μm is attached to the inner side of the shell at the drilling site to obtain a modified positive electrode shell;

[0052] S4: Assemble the battery. Use the gelatinized positive electrode slurry prepared in S1 as the positive electrode slurry, the slow-release gelatinized electrolyte prepared in S2 as the electrolyte, magnesium metal or magnesium alloy as the negative electrode, glass fiber as the separator, and the modified positive electrode shell obtained in S3 as the positive electrode shell. Assemble to obtain a magnesium-aqueous primary button cell, such as... Figure 1 As shown, in this embodiment, the negative electrode is pure magnesium metal, the magnesium foil has a thickness of 100 μm and a diameter of 14 mm; the positive electrode slurry has a mass of 50 mg, and the electrolyte volume is 200 μL.

[0053] Battery testing: The magnesium-aqueous primary button cell prepared in S4 was discharged at a current density of 10 mA / g to test its discharge time and discharge capacity.

[0054] Test results are as follows Figure 3As shown in the figure, the primary battery exhibits excellent electrochemical performance due to the combined effects of the positive electrode structure, the negative electrode interface, and the gelatinized electrolyte. Its discharge curve is relatively flat, with a discharge time of up to 7.7 hours and a discharge capacity of up to 20 mAh.

[0055] Comparative Example 1

[0056] Unlike embodiment 1, manganese dioxide is used as the positive electrode, magnesium bromide as the electrolyte, magnesium metal as the negative electrode, and glass fiber as the separator to assemble a magnesium aqueous primary button cell. Figure 4 As shown, the resulting magnesium primary battery has a discharge time of only 1.2 hours and a discharge capacity of 3.1 mAh.

[0057] Comparative Example 2

[0058] Unlike Example 1, in the preparation method of a magnesium aqueous primary battery system, the concentration of sodium fluoride in S2 is 0.03 mol / L. For example... Figure 5 As shown, the resulting magnesium primary battery has a discharge time of only 3.8 hours and a discharge capacity of 9.8 mAh.

[0059] Comparative Example 3

[0060] Unlike Example 1, in the preparation method of a magnesium aqueous primary battery system, the concentration of sodium fluoride in S2 is 0.2 mol / L. For example... Figure 6 As shown, the resulting magnesium primary battery has a discharge time of only 5.8 hours and a discharge capacity of 16.1 mAh.

[0061] Comparative Example 4

[0062] Unlike Example 1, in the preparation method of a magnesium-aqueous primary battery system, in S3, the positive electrode steel shell is intact and without holes. Figure 7 As shown, the resulting magnesium primary battery has a discharge time of only 2.3 hours and a discharge capacity of 6.8 mAh.

[0063] Comparative Example 5

[0064] Unlike Example 1, in the preparation method of a magnesium-water-based primary battery system, in S2, the positive electrode steel shell is perforated but not covered with a waterproof and breathable membrane. Figure 8 As shown, the resulting magnesium primary battery has a discharge time of only 4.2 hours and a discharge capacity of 12.1 mAh.

[0065] Table 1 shows the performance test results of the magnesium aqueous primary button batteries assembled in Example 1 and Comparative Examples 1-5.

[0066] Table 1

[0067] sample Discharge time (h) Discharge capacity (mAh) Is there bloating? Example 1 7.7 20 no Comparative Example 1 1.2 3.1 yes Comparative Example 2 3.8 9.8 yes Comparative Example 3 5.8 16.1 no Comparative Example 4 2.3 6.8 yes Comparative Example 5 4.2 12.1 no

[0068] As shown in Table 1, by comparing Example 1 and Comparative Example 1, it can be found that the present technical solution can significantly extend the discharge time of the battery and increase the discharge capacity of the battery by optimizing the positive electrode material, electrolyte and positive electrode steel shell, and will not cause gas swelling.

[0069] By comparing Example 1 with Comparative Examples 2-3, it was found that if the concentration of the corrosion inhibitor is too high, it will reduce the rate of the electrochemical reaction of the primary battery, resulting in a decrease in discharge time and discharge capacity; if the concentration of the corrosion inhibitor is too low, it will not achieve a good corrosion inhibition effect, leading to battery bulging and gas swelling during the reaction process, reducing the safety of magnesium primary batteries.

[0070] By comparing Example 1 and Comparative Example 4, it was found that without drilling holes in the positive electrode steel shell, the gas generated during the battery reaction was difficult to release, and the gas would accumulate inside the battery, causing bloating. As a result, the battery's discharge time was shortened and the discharge capacity was reduced.

[0071] By comparing Example 1 and Comparative Example 5, it was found that although the battery did not swell due to the perforation of the positive electrode steel shell without covering it with a waterproof and breathable membrane, the discharge time and discharge capacity of the battery were shortened because the positive electrode part of the battery was exposed to the air, which caused the activity of the active material to decrease.

[0072] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A magnesium-aqueous primary battery system, characterized in that: It includes a positive electrode, a negative electrode, and an electrolyte. The negative electrode is any one of magnesium metal and magnesium alloy. The positive electrode is made of positive electrode active material, superconducting carbon, and No. 1 gelling agent. The electrolyte is made of magnesium bromide electrolyte, corrosion inhibitor, and No. 2 gelling agent. The corrosion inhibitor is any one or more of lithium fluoride, sodium fluoride, potassium fluoride, and magnesium fluoride, and the positive electrode active material is manganese dioxide; the first gelatinizing agent is any one or more of superabsorbent resin, hydroxypropyl starch, and starch-based bioplastics; the second gelatinizing agent is any one or more of corn starch, wheat starch, and potato starch.

2. A method for preparing a magnesium-aqueous primary battery system, characterized in that: Includes the following steps: S1: Prepare positive electrode slurry by mixing positive electrode active material, superconducting carbon and No. 1 gelatinizing agent in a certain mass ratio to obtain gelatinized positive electrode slurry, wherein the positive electrode active material is manganese dioxide and the No. 1 gelatinizing agent is any one or more combinations of superabsorbent resin, hydroxypropyl starch and starch-based bioplastics. S2: Prepare an electrolyte by introducing a corrosion inhibitor into a magnesium bromide electrolyte and then adding a second gelatinizing agent for gelatinization treatment to obtain a slow-release gelatinized electrolyte. The corrosion inhibitor is any one or a combination of lithium fluoride, sodium fluoride, potassium fluoride and magnesium fluoride; the second gelatinizing agent is any one or a combination of corn starch, wheat starch and potato starch. S3: Prepare a positive electrode steel shell, perform a perforation operation on the positive electrode steel shell, and attach a waterproof and breathable membrane at the perforation point to obtain a modified positive electrode shell. S4: Assemble the battery by using the gelatinized positive electrode slurry prepared in S1 as the positive electrode slurry, the slow-release gelatinized electrolyte prepared in S2 as the electrolyte, magnesium metal or magnesium alloy as the negative electrode, glass fiber as the separator, and the modified positive electrode shell obtained in S3 as the positive electrode shell, and assemble them to obtain a magnesium aqueous primary battery.

3. The method for preparing a magnesium aqueous primary battery system according to claim 2, characterized in that: The mass ratio of the positive electrode active material, superconducting carbon, and gelatinizing agent No. 1 in S1 is 8:2:(0.3-2).

4. The method for preparing a magnesium aqueous primary battery system according to claim 3, characterized in that: The mass ratio of magnesium bromide, corrosion inhibitor, and No. 2 gelling agent in S2 is 10:1:(1-2).

5. The method for preparing a magnesium aqueous primary battery system according to claim 4, characterized in that: The concentration of corrosion inhibitor in S2 is 0.05-0.15 mol / L.

6. The method for preparing a magnesium aqueous primary battery system according to claim 5, characterized in that: The aperture of the positive electrode shell in S3 is 0.1-2mm.

7. The method for preparing a magnesium aqueous primary battery system according to claim 6, characterized in that: The thickness of the waterproof and breathable membrane in S3 is 20-100μm.

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