Magnesium water system primary battery system and preparation method thereof

Abstract

The invention relates to the technical field of magnesium primary battery preparation, and discloses a magnesium aqueous primary battery system, which comprises 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 prepared from a positive electrode active material, superconducting carbon and a No.1 gelatinizing agent, and the electrolyte is prepared from magnesium bromide, a corrosion inhibitor and a No.2 gelatinizing agent; the preparation method comprises the following steps: S1, preparing positive electrode slurry; s2, an electrolyte is prepared, a corrosion inhibitor is introduced into the magnesium bromide electrolyte, then a second gelatinizing agent is added for gelatinizing treatment, and a slow-release gelatinized electrolyte is prepared; s3, preparing a positive electrode steel shell; and S4, assembling the battery. According to the technical scheme, the corrosion speed of the negative electrode material can be slowed down, the utilization rate of the negative electrode material is improved, and meanwhile, the problems of voltage lag and volume expansion during battery discharging can be solved; in addition, the reaction rates of the positive and negative electrodes of the battery can be matched.

Description

Technical Field

[0001] The present invention relates to the technical field of magnesium primary battery preparation, and in particular to a magnesium aqueous primary battery system and a preparation method thereof. Background Art

[0002] In the current global development context, the energy shortage problem is becoming increasingly serious, which has become one of the important factors restricting the sustainable development of human society. At the same time, environmental awareness has been deeply rooted in people's minds, and people's requirements for environmental protection in all aspects of production and life are getting higher and higher. Under such a dual background, the battery industry is facing huge challenges and opportunities, and the demand for new high-performance batteries is becoming more urgent.

[0003] Magnesium primary batteries have attracted much attention due to the relatively negative electrode potential of magnesium, which significantly improves the theoretical specific capacity, open circuit voltage and specific energy of magnesium batteries. Compared with ordinary zinc-manganese dry batteries, magnesium primary batteries have about twice the charge capacity of ordinary zinc-manganese dry batteries at the same volume, and have good temperature adaptability, which has potential value in specific scenarios.

[0004] However, despite the above advantages, magnesium primary batteries face many serious problems in practical applications, which greatly limit their widespread application.

[0005] First, during the battery discharge process, the oxide film on the surface of the magnesium negative electrode is destroyed after partial discharge, the negative electrode material loses protection, the self-corrosion rate is accelerated, the effective ingredients are reduced, and the utilization rate of the negative electrode material is reduced, affecting the battery performance and service life.

[0006] Secondly, there is a voltage lag when the battery is discharged, and it takes some time to reach the normal level, which will affect the startup and operation of the equipment. In addition, the volume of the battery expands severely after discharge, which may cause the shell to deform and crack, not only damaging the equipment, but also causing safety hazards due to leakage of internal battery substances.

[0007] Third, the mismatch between the reaction rates of the positive and negative electrodes of magnesium primary batteries is a prominent problem. The magnesium negative electrode is active and reacts quickly, while the positive electrode reacts slowly, resulting in low utilization of the magnesium negative electrode, which seriously restricts its actual application effect. In order to solve this problem, researchers introduced corrosion inhibitors to alleviate the corrosion of the negative electrode, but this caused new problems. Due to the dense structure of the positive electrode, it is difficult for the electrolyte to fully penetrate into the interior of the positive electrode. The positive electrode reaction is still slow, resulting in low electrochemical capacity and shortened discharge time. If only the positive electrode preparation process is improved to make the positive electrode have a loose structure, although the positive electrode activity will be improved, it will lead to rapid reaction on the negative electrode side, generating a large amount of gas in a short period of time, and eventually causing the battery to swell and crack, and fail instantly.

[0008] In summary, these problems of magnesium primary batteries seriously hinder their development and application. Therefore, it is urgent to build an intrinsically safe and stable magnesium aqueous primary battery system. New technology solutions are urgently needed to solve these problems, promote the development of magnesium battery technology, and meet the 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 a preparation method thereof, so as to overcome the problems existing in the prior art.

[0010] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: 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 more combinations of lithium fluoride, sodium fluoride, potassium fluoride and magnesium fluoride.

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

[0013] Preferably, the first gelatinizer is a combination of any one or more of highly absorbent resin, hydroxypropyl starch and starch-based bioplastics; the second gelatinizer is a combination of any one or more of corn starch, wheat starch and potato starch.

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

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

[0016] S2: preparing an electrolyte, introducing a corrosion inhibitor into the magnesium bromide electrolyte, and then adding a second gelatinizer for gelatinization to obtain a slow-release gelatinized electrolyte;

[0017] S3: preparing a positive electrode steel shell, performing a hole punching operation on the positive electrode steel shell, and attaching a waterproof and breathable film to the punched position to obtain a modified positive electrode shell;

[0018] S4: Assemble the battery, 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 to obtain a magnesium aqueous primary battery.

[0019] Preferably, the mass ratio of the positive electrode active material, the superconducting carbon and the first pasting agent in S1 is 8:2:(0.3-2).

[0020] Preferably, the mass ratio of magnesium bromide, corrosion inhibitor and No. 2 pasteurizer 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 waterproof breathable membrane in S3 has a thickness of 20-100 μm.

[0024] Principle of this technical solution: Through extensive research and experiments by the inventors, a variety of improvement methods are combined to solve the existing problems of magnesium aqueous primary batteries and improve performance. First, a second gelatinizer and a sustained-release agent are introduced into the electrolyte to simultaneously process the positive electrode powder material and improve the battery shell. The role of the second gelatinizer and the sustained-release agent in the electrolyte cooperates with the treatment of the positive electrode powder material and the improvement measures of the battery shell to form a coordinated control. These methods affect the working process of the battery from multiple aspects, effectively improving the mismatch problem of the positive and negative electrode reaction rates, avoiding the degradation of battery performance due to the difference in reaction rates; alleviating the problem of volume expansion, preventing damage to the battery structure due to expansion; eliminating voltage hysteresis to ensure stable power supply of the battery; improving the utilization rate of the negative electrode material and reducing material waste. Through these improvements, the electrochemical capacity and discharge time of the battery are further improved.

[0025] In addition, the positive electrode slurry and electrolyte are double gelatinized. This double gelatinization design is beneficial to improving the reaction rate of the positive electrode active material for the positive electrode, so that the positive electrode can participate in the reaction more efficiently in the battery reaction. For the negative electrode, double gelatinization can effectively reduce the contact between the electrolyte and the negative electrode, thereby reducing the reaction rate of the negative electrode. By adjusting the reaction rates of the positive and negative electrodes separately, the effect of improving the matching degree of the positive and negative electrode reactions is achieved, and the overall reaction coordination of the battery is optimized.

[0026] In addition, a hole is punched on the positive electrode side of the battery and a waterproof and breathable membrane is attached. During the operation of the battery, excess hydrogen will be generated. Punching can provide a release channel for hydrogen to prevent hydrogen from accumulating inside the battery. At the same time, this treatment method reduces the system pressure and reduces the direct contact between the negative electrode interface and the electrolyte. This series of effects further improves the working life of the magnesium aqueous primary battery and ensures that the battery can operate stably and safely for a long time.

[0027] Compared with the prior art, this solution has the following beneficial effects:

[0028] (1) Solve the negative electrode problems of the prior art and improve the negative electrode performance: In order to solve the problem that the oxide film on the surface of the magnesium negative electrode is destroyed during the battery discharge process, which leads to accelerated self-corrosion, reduced effective ingredients, and reduced negative electrode utilization, this solution reduces the side reaction between water and the magnesium negative electrode in the aqueous electrolyte through the slow release effect of the fluoride corrosion inhibitor in the electrolyte and the gelatinization function of the second gelatinizer, reduces the negative electrode self-corrosion, and improves the utilization rate of the negative electrode material, thereby improving the battery performance and service life.

[0029] (2) Solve the problems of voltage hysteresis and volume expansion: Corrosion inhibitors and double gelatinization effectively improve the contact efficiency of the components of the primary battery, greatly reduce the internal resistance of the battery, and effectively overcome the problem of voltage hysteresis during battery discharge that affects the startup and operation of the equipment. At the same time, it alleviates the potential safety hazards caused by the expansion of the battery volume after discharge, which may lead to deformation and rupture of the outer shell and leakage of internal battery substances, thereby ensuring the safe and stable operation of the equipment.

[0030] (3) Improve the matching problem of positive and negative electrode reaction rates: Improve the prominent problem of mismatch between the positive and negative electrode reaction rates of magnesium aqueous primary batteries. Introduce No. 1 gelatinizer into the positive electrode slurry to reconstruct the dispersibility of the positive electrode slurry, build excellent ion and electron transmission channels in the positive electrode material, and effectively improve the reaction rate of the positive electrode active material; at the same time, double gelatinization (positive electrode slurry and electrolyte) reduces the contact between the electrolyte and the negative electrode, reduces the reaction rate of the negative electrode, and improves the matching degree of the positive and negative electrode reactions. In addition, it avoids the problem of rapid reaction on the negative electrode side and generation of a large amount of gas that causes the battery to swell and crack due to only improving the positive electrode preparation process to make the positive electrode loose, thereby improving the stability and safety of the battery; the addition of superconducting carbon enhances the conductivity of the positive electrode.

[0031] (4) Improve electrochemical performance and battery safety: Through the combined action of various means, the kinetic matching of the positive and negative electrode reactions is optimized, the generation of reaction gas is reduced, and the electrochemical capacity and discharge time are improved. The positive electrode steel shell punching process can effectively release the gas generated during the reaction of the primary aqueous magnesium battery. The introduction of a waterproof and breathable membrane at the punching point can prevent slurry overflow, thereby improving the intrinsic safety of the magnesium primary battery.

[0032] (5) Process advantages: The preparation process provided in this application is simple and efficient, with good product batch consistency, and can be widely used in aqueous button primary batteries, with good prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of a magnesium aqueous primary battery system in Example 1 of the present invention;

[0034] Figure 2 This is a rendering of the effect of the sustained-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 Invention Example 1;

[0036] Figure 4 This is a constant current discharge diagram of a magnesium aqueous primary battery system in comparative example 1 of the invention;

[0037] Figure 5 This is a constant current discharge diagram of a magnesium aqueous primary battery system in comparative example 2 of the invention;

[0038] Figure 6 This is a constant current discharge diagram of a magnesium aqueous primary battery system in comparative example 3 of the invention;

[0039] Figure 7 This is a constant current discharge diagram of a magnesium aqueous primary battery system in comparative example 4 of the invention;

[0040] Figure 8 This is a constant current discharge diagram of a magnesium aqueous primary battery system in comparative example 5 of the invention. DETAILED DESCRIPTION

[0041] The following is further described in detail through specific implementation methods:

[0042] Example 1

[0043] A magnesium aqueous primary battery system comprises 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.

[0044] Wherein, the corrosion inhibitor is any one or more combinations of lithium fluoride, sodium fluoride, potassium fluoride and magnesium fluoride. In this embodiment, the corrosion inhibitor is sodium fluoride;

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

[0046] The first gelatinizer is one or more of highly absorbent resin, hydroxypropyl starch and starch-based bioplastics. In the present embodiment, the first gelatinizer is a highly absorbent resin.

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

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

[0049] S1: Prepare positive electrode slurry, mix the positive electrode active material, superconducting carbon and No. 1 gelling agent in a certain mass ratio to obtain gelatinized positive electrode slurry; wherein the mass ratio of the positive electrode active material, superconducting carbon and No. 1 gelling agent is 8:2:(0.3-2). In this embodiment, after grinding and mixing manganese dioxide and superconducting carbon, add them to the super absorbent resin solution and stir them evenly to obtain gelatinized positive electrode slurry, the amount of manganese dioxide is 8g, the amount of superconducting carbon is 2g, and the amount of super absorbent resin is 1g;

[0050] S2: preparing an electrolyte, introducing a corrosion inhibitor into the magnesium bromide electrolyte, and then adding a second gelatinizer for gelatinization to obtain a slow-release gelatinized electrolyte; wherein the mass ratio of magnesium bromide, corrosion inhibitor and second gelatinizer 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 of magnesium bromide and 0.1 mol / L of sodium fluoride are respectively prepared, and the two are mixed evenly, and 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 a slow-release gelatinized electrolyte such as Figure 2 As shown, the amount of magnesium bromide is 5 g, the amount of sodium fluoride is 0.5 g, and the amount of corn starch is 0.75 g;

[0051] S3: preparing a positive electrode steel shell, punching the positive electrode steel shell, and attaching a waterproof breathable film to the punched holes to obtain a modified positive electrode shell; wherein the hole diameter on the positive electrode shell is 0.1-2 mm, and the thickness of the waterproof breathable film is 20-100 μm; in this embodiment, a 1 mm puncher is used to drill a hole in the center of the positive electrode shell, and the surface of the punched hole is heat-treated, and a layer of a waterproof breathable film with a thickness of 30 μm is attached to the inner side of the shell at the punched hole 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, and assemble to obtain a magnesium aqueous primary button battery such as Figure 1 As shown, in this embodiment, the negative electrode is pure magnesium metal, the thickness of the magnesium foil is 100 μm, and the diameter is 14 mm; the mass of the positive electrode slurry is 50 mg, and the volume of the electrolyte is 200 μL.

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

[0054] Test results such as Figure 3As shown in the figure, under the combined effect of the positive electrode structure, the negative electrode interface and the gelled electrolyte, the primary battery exhibits relatively excellent electrochemical performance. Its discharge curve is relatively flat, the discharge time can reach 7.7h, and the discharge capacity can reach 20mAh.

[0055] Comparative Example 1

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

[0057] Comparative Example 2

[0058] Different from Example 1, in a method for preparing a magnesium aqueous primary battery system, in S2, the concentration of sodium fluoride is 0.03 mol / L. Figure 5 As shown, the discharge time of the obtained magnesium primary battery is only 3.8h and the discharge capacity is 9.8mAh.

[0059] Comparative Example 3

[0060] Different from Example 1, in a method for preparing a magnesium aqueous primary battery system, the concentration of sodium fluoride in S2 is 0.2 mol / L. Figure 6 As shown, the discharge time of the obtained magnesium primary battery is only 5.8h and the discharge capacity is 16.1mAh.

[0061] Comparative Example 4

[0062] Different from Example 1, in a method for preparing a magnesium aqueous primary battery system, in S3, the positive electrode steel shell is intact and not perforated. Figure 7 As shown, the discharge time of the obtained magnesium primary battery is only 2.3h and the discharge capacity is 6.8mAh.

[0063] Comparative Example 5

[0064] Different from Example 1, in a method for preparing a magnesium aqueous primary battery system, in S2, the positive electrode steel shell is perforated and not covered with a waterproof and breathable membrane. Figure 8 As shown, the discharge time of the obtained magnesium primary battery is only 4.2h and the discharge capacity is 12.1mAh.

[0065] Table 1 shows the performance test results of 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) Whether there is 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 can be seen from Table 1, by comparing Example 1 with Comparative Example 1, it is found that the technical solution can significantly prolong the discharge time of the battery and increase the discharge capacity of the battery without causing flatulence by optimizing the positive electrode material, the electrolyte and the positive electrode steel shell.

[0069] By comparing Example 1 with Comparative Examples 2-3, it is found that if the concentration of the corrosion inhibitor is too high, the rate of the electrochemical reaction of the primary battery will be reduced, resulting in a decrease in the discharge time and discharge capacity; if the concentration of the corrosion inhibitor is too low, a good corrosion inhibition effect cannot be achieved, resulting in battery bulging and gas expansion during the reaction, thereby reducing the safety of the magnesium primary battery.

[0070] By comparing Example 1 with Comparative Example 4, it is found that the positive electrode steel shell is not perforated, the gas generated during the reaction of the battery is difficult to release, and the gas will accumulate inside the battery and cause bloating, thereby shortening the discharge time of the battery and reducing the discharge capacity.

[0071] By comparing Example 1 with Comparative Example 5, it is found that when the positive electrode steel shell is perforated but not covered with a waterproof breathable film, although the battery will not experience bloating, the positive electrode portion of the battery is exposed to the air, causing the activity of the active material to decrease. Therefore, the discharge time of the battery is shortened and the discharge capacity is also reduced.

[0072] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records 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, wherein 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 a first gelling agent, and the electrolyte is made of magnesium bromide, a corrosion inhibitor and a second gelling agent.

2. The magnesium aqueous primary battery system according to claim 1, characterized in that: The corrosion inhibitor is any one or more combinations of lithium fluoride, sodium fluoride, potassium fluoride and magnesium fluoride.

3. The magnesium aqueous primary battery system according to claim 1, characterized in that: The positive electrode active material is manganese dioxide.

4. The magnesium aqueous primary battery system according to claim 1, characterized in that: The first gelatinizer is any one or more combinations of highly absorbent resin, hydroxypropyl starch and starch-based bioplastics; the second gelatinizer is any one or more combinations of corn starch, wheat starch and potato starch.

5. A method for preparing a magnesium aqueous primary battery system, characterized in that: The following steps are involved: S1: preparing positive electrode slurry, mixing positive electrode active material, superconducting carbon and No. 1 gelling agent in a certain mass ratio to obtain gelatinized positive electrode slurry; S2: preparing an electrolyte, introducing a corrosion inhibitor into the magnesium bromide electrolyte, and then adding a second gelatinizer for gelatinization to obtain a slow-release gelatinized electrolyte; S3: preparing a positive electrode steel shell, performing a hole punching operation on the positive electrode steel shell, and attaching a waterproof and breathable film to the punched position to obtain a modified positive electrode shell; S4: Assemble the battery, 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 to obtain a magnesium aqueous primary battery.

6. The method for preparing a magnesium aqueous primary battery system according to claim 5, characterized in that: The mass ratio of the positive electrode active material, superconducting carbon and No. 1 pasting agent in S1 is 8:2:(0.3-2).

7. The method for preparing a magnesium aqueous primary battery system according to claim 6, characterized in that: The mass ratio of magnesium bromide, corrosion inhibitor and No. 2 pasteurizer in S2 is 10:1:(1-2).

8. The method for preparing a magnesium aqueous primary battery system according to claim 7, characterized in that: The concentration of corrosion inhibitor in S2 is 0.05-0.15 mol / L.

9. The method for preparing a magnesium aqueous primary battery system according to claim 8, characterized in that: The hole diameter on the positive electrode shell in S3 is 0.1-2mm.

10. The method for preparing a magnesium aqueous primary battery system according to claim 9, characterized in that: The thickness of the waterproof and breathable membrane in S3 is 20-100 μm.

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