Positive electrode additive of alkaline zinc-manganese battery with high open-circuit voltage and application of positive electrode additive

Abstract

The invention relates to the technical field of battery manufacturing, in particular to a positive electrode additive of a high open-circuit voltage alkaline zinc-manganese battery and application of the positive electrode additive, the additive is potassium persulfate, and a positive electrode material containing the additive comprises the following raw materials: electrolytic manganese dioxide, graphite, calcium stearate and potassium persulfate. The positive electrode additive is rich in raw materials and low in cost, and can be simply and uniformly mixed with a positive electrode material, so that the operation is simple, convenient and efficient; besides, by utilizing the characteristics of high standard electrode potential and strong oxidizing property of potassium persulfate, the open-circuit voltage of the battery can be effectively improved, the discharge performance of the battery is improved, the high-voltage state is always kept in the storage process, and the storage performance of the battery is improved.

Description

Technical Field

[0001] The invention relates to the technical field of battery manufacturing, and in particular to a positive electrode additive for an alkaline zinc-manganese battery with a high open circuit voltage and an application thereof. Background Art

[0002] Alkaline zinc-manganese battery is a common chemical power source with the advantages of low cost, high safety and environmental friendliness. It is widely used in portable electronic devices, toys, lighting and other fields. The open circuit voltage of alkaline zinc-manganese battery is mainly determined by the electrode potential difference between the positive electrode material (electrolytic manganese dioxide) and the negative electrode material (zinc). The open circuit voltage of traditional alkaline zinc-manganese battery is usually around 1.55V, while the actual working voltage will be lower. This is mainly because there is an inevitable self-discharge phenomenon in alkaline zinc-manganese batteries during storage, which causes the battery open circuit voltage to gradually decrease and shortens the storage life of the battery. Although the open circuit voltage of alkaline zinc-manganese batteries of most domestic and foreign brands is roughly 1.5V, the open circuit voltage of new batteries of some advanced brands (Nanfu, Energizer, etc.) will be slightly higher (about 1.6V), which means that they can provide a slightly higher initial output voltage and can be used for equipment that requires high power startup.

[0003] At present, the research on open circuit voltage mainly focuses on slowing down the self-discharge of the negative electrode, but this research can only slow down the rate of voltage drop, and cannot substantially increase the open circuit voltage of the battery. Therefore, how to simply and effectively increase the open circuit voltage of alkaline batteries without affecting the discharge performance of the battery still needs further exploration and research and development. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a positive electrode additive for an alkaline zinc-manganese battery with a high open circuit voltage. The main component of the positive electrode additive is potassium persulfate. With the help of the high standard electrode potential of potassium persulfate, not only can the open circuit voltage of the battery be significantly improved, but also a high voltage state can be always maintained during the storage process, thereby improving the storage performance of the battery; and the strong oxidizing property of potassium persulfate oxidizes part of the MnOOH generated by self-discharge into active MnO2 to re-participate in the discharge, thereby reducing the positive electrode polarization caused by the accumulation of MnOOH, and significantly improving the discharge performance under the 3.9Ω discharge mode; in addition, the positive electrode additive is not only rich in raw materials and low in cost, but also can obtain significant effects by adding a small amount, and has high economic benefits.

[0005] Another object of the present invention is to provide an application of a positive electrode additive for an alkaline zinc-manganese battery with a high open circuit voltage. The method is simple, efficient and cost-controlled. It only requires simple and uniform mixing with the positive electrode material. The produced product has high quality and good consistency and can be directly put into industrial production. At the same time, it can significantly improve the open circuit voltage, discharge performance and storage performance of the battery.

[0006] The object of the present invention is achieved by the following technical solutions: A positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, the positive electrode additive contains potassium persulfate, and the positive electrode material containing the positive electrode additive is composed of the following raw materials: electrolytic manganese dioxide, graphite, calcium stearate, potassium persulfate, and positive electrode electrolyte; wherein, the dosage of potassium persulfate is 0.1%-1% of the mass fraction of electrolytic manganese dioxide.

[0007] Further, the positive electrode material includes the following raw materials in parts by weight: 86-91 parts of electrolytic manganese dioxide, 6-10 parts of graphite, 0.3-1.0 part of calcium stearate, 0.08-1.0 part of potassium persulfate, and 2-5 parts of positive electrode electrolyte.

[0008] Preferably, the positive electrode material is composed of the following raw materials in parts by weight: 86-91 parts of electrolytic manganese dioxide, 6-9 parts of graphite, 0.3 part of calcium stearate, 0.08-1.0 part of potassium persulfate, and 2-5 parts of positive electrode electrolyte.

[0009] Preferably, the positive electrode electrolyte is a 40% wt potassium hydroxide solution.

[0010] Preferably, the graphite is one or several of expanded graphite, semi-expanded graphite, and flake graphite.

[0011] In the technical solution of the present invention, since the electrode potential of potassium persulfate used in the positive electrode additive is higher than that of manganese dioxide, the addition of potassium persulfate increases the electrode potential of the positive electrode, increases the potential difference between the positive and negative electrodes, and improves the open-circuit voltage of the alkaline zinc-manganese battery. During the storage of the battery, an inevitable slow self-discharge reaction will occur, as shown in Equation 1:

[0012] Zn + 2MnO2 + H2O → 2MnOOH + ZnO (1);

[0013] As the self-reaction proceeds, the active MnO2 at the positive electrode is continuously consumed, resulting in a decrease in capacity, and the accumulation of the generated MnOOH will cause polarization of the electrode, resulting in a voltage drop. Potassium persulfate has strong oxidizing properties and can oxidize some of the MnOOH generated due to self-discharge into active MnO2 to participate in the discharge reaction again, reducing the positive electrode polarization caused by the accumulation of MnOOH and offsetting part of the capacity lost due to self-discharge, thereby improving the discharge performance and storage performance of the alkaline zinc-manganese battery. This is completely different from the mechanism of action of the positive electrode additive using barium sulfate in the past, whose main role is to increase the porosity of the cathode ring to improve the ionic conductivity to enhance the high-current discharge performance.

[0014] The present invention also provides an application of a positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, including the following steps:

[0015] S1. Mix electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate by weight parts and dry blend them evenly to obtain mixture A for standby.

[0016] S2. Add the positive electrode electrolyte to mixture A by weight parts and stir until homogeneous to obtain mixture B for standby.

[0017] S3. Press, granulate, and form a ring for mixture B to obtain the positive electrode material.

[0018] The application method of the positive electrode additive of the high open-circuit voltage alkaline zinc-manganese battery in the present invention is as described above. This application method is simple, easy to operate, highly efficient, cost controllable, the produced products have high quality and good consistency, can directly enter industrial production, and can significantly improve the open-circuit voltage, discharge performance, and storage performance of the battery.

[0019] The beneficial effects of the present invention are as follows:

[0020] (1) In the present invention, potassium persulfate is used as the positive electrode additive. Since the electrode potential of potassium persulfate is higher than that of manganese dioxide, the addition of potassium persulfate increases the electrode potential of the positive electrode, enlarges the potential difference between the positive and negative electrodes, and improves the open-circuit voltage of the alkaline zinc-manganese battery. At the same time, potassium persulfate has strong oxidizing properties and can oxidize some MnOOH generated by self-discharge into active MnO2 to participate in the discharge reaction again, reducing the positive electrode polarization caused by the accumulation of MnOOH and offsetting part of the capacity lost due to self-discharge, thereby improving the discharge performance and storage performance of the alkaline zinc-manganese battery. In addition, as a positive electrode additive, potassium persulfate not only has rich raw materials and low cost, but also can obtain significant effects with a small amount of addition, and has high economic benefits.

[0021] (2) The application of the positive electrode additive of the high open-circuit voltage alkaline zinc-manganese battery in the present invention has a simple application method, is easy to operate, highly efficient, cost controllable, the produced products have high quality and good consistency, can directly enter industrial production, and can significantly improve the open-circuit voltage, discharge performance, and storage performance of the battery. Description of the Drawings

[0022] Figure 1 It is a comparison chart of the open-circuit voltages of LR6-type batteries prepared from the positive electrode materials in Comparative Example 1 and Example 2 stored at room temperature for different times;

[0023] Figure 2 It is a comparison chart of the open-circuit voltages of LR6-type batteries prepared from the positive electrode materials in Comparative Example 1 and Example 2 stored at 60 °C for different times;

[0024] Figure 3It is a comparison chart of the discharge time and the discharge time decay rate of the LR6 type battery prepared with the cathode materials in Embodiment 2 and Comparative Example 1 after 30 days of storage at room temperature under the mode of continuously discharging at a constant resistance of 3.9 Ω until 0.9 V.

[0025] Figure 4 It is a comparison chart of the discharge time and the discharge time decay rate of the LR6 type battery prepared with the cathode materials in Embodiment 2 and Comparative Example 1 after 5 weeks of storage at high temperature under the mode of continuously discharging at a constant resistance of 3.9 Ω until 0.9 V.

[0026] Figure 5 It is the discharge curve of the LR6 type battery prepared with the cathode materials in Embodiment 1, Embodiment 2 and Embodiment 3 after standing for 24 hours under the mode of continuously discharging at a constant resistance of 3.9 Ω until 0.9 V. Detailed implementation manners

[0027] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the embodiments and the attached Figures 1-5 It is not intended to limit the present invention by the content mentioned in the implementation manners.

[0028] Embodiment 1

[0029] A cathode additive for a high open-circuit voltage alkaline zinc-manganese battery, the cathode additive contains potassium persulfate, and the cathode material containing the cathode additive is composed of the following raw materials: 90 parts of electrolytic manganese dioxide, 8 parts of graphite, 0.3 part of calcium stearate, 0.09 part of potassium persulfate and 4 parts of cathode electrolyte; the cathode electrolyte is a 40% wt potassium hydroxide solution.

[0030] An application of a cathode additive for a high open-circuit voltage alkaline zinc-manganese battery, including the following steps:

[0031] S1. According to parts by weight, mix electrolytic manganese dioxide, graphite, calcium stearate and potassium persulfate and dry-mix them evenly to obtain mixture A for standby;

[0032] S2. According to parts by weight, add the cathode electrolyte to mixture A and stir until uniform to obtain mixture B for standby;

[0033] S3. Press, granulate and form a ring for mixture B to obtain the cathode material.

[0034] Prepare finished LR6 type alkaline zinc-manganese batteries with the above-prepared cathode materials according to the existing alkaline zinc-manganese battery production process, and test the open-circuit voltage and discharge performance of the batteries after storing at room temperature and in an oven at 60 °C for different times respectively.

[0035] Embodiment 2

[0036] A positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, the positive electrode additive contains potassium persulfate, and the positive electrode material containing the positive electrode additive is composed of the following raw materials: 90 parts of electrolytic manganese dioxide, 8 parts of graphite, 0.3 parts of calcium stearate, 0.45 parts of potassium persulfate, and 4 parts of positive electrode electrolyte; the positive electrode electrolyte is a 40% wt potassium hydroxide solution.

[0037] An application of a positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, including the following steps:

[0038] S1. According to weight parts, mix electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate and dry-mix them evenly to obtain mixture A for standby;

[0039] S2. According to weight parts, add the positive electrode electrolyte to mixture A and stir until evenly mixed to obtain mixture B for standby;

[0040] S3. Press, granulate, and form a ring for mixture B to obtain the positive electrode material.

[0041] Prepare the finished LR6 type alkaline zinc-manganese battery with the above-prepared positive electrode material according to the existing alkaline zinc-manganese battery production process, and test the open-circuit voltage and discharge performance of the prepared battery after storing for different times in a normal temperature and 60 °C oven respectively.

[0042] Example 3

[0043] A positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, the positive electrode additive contains potassium persulfate, and the positive electrode material containing the positive electrode additive is composed of the following raw materials: 90 parts of electrolytic manganese dioxide, 8 parts of graphite, 0.3 parts of calcium stearate, 0.9 parts of potassium persulfate, and 4 parts of positive electrode electrolyte; the positive electrode electrolyte is a 40% wt potassium hydroxide solution.

[0044] An application of a positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, including the following steps:

[0045] S1. According to weight parts, mix electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate and dry-mix them evenly to obtain mixture A for standby;

[0046] S2. According to weight parts, add the positive electrode electrolyte to mixture A and stir until evenly mixed to obtain mixture B for standby;

[0047] S3. Press, granulate, and form a ring for mixture B to obtain the positive electrode material.

[0048] Prepare the finished LR6 type alkaline zinc-manganese battery with the above-prepared positive electrode material according to the existing alkaline zinc-manganese battery production process, and test the open-circuit voltage and discharge performance of the prepared battery after storing for different times in a normal temperature and 60 °C oven respectively.

[0049] Comparative Example 1

[0050] A cathode material for alkaline zinc-manganese batteries, comprising components in the following parts by mass: 90 parts of electrolytic manganese dioxide, 8 parts of graphite, 0.3 part of calcium stearate, and 4 parts of cathode electrolyte; the cathode electrolyte is a 40% wt potassium hydroxide solution.

[0051] An application of a cathode additive for high open-circuit voltage alkaline zinc-manganese batteries, comprising the following steps:

[0052] S1. According to parts by weight, mix electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate and dry-mix them evenly to obtain mixture A for standby.

[0053] S2. According to parts by weight, add the cathode electrolyte to mixture A and stir until uniform to obtain mixture B for standby.

[0054] S3. Press, granulate, and form a ring for mixture B to obtain the cathode material.

[0055] Prepare finished LR6-type alkaline zinc-manganese batteries from the above-prepared cathode material according to the existing production process of alkaline zinc-manganese batteries, and test the open-circuit voltage and discharge performance of the batteries after storing them at room temperature and in an oven at 60°C for different times.

[0056] Perform performance tests on the cathode materials prepared in the examples and comparative examples:

[0057] Figure 1 It is a comparison chart of the open-circuit voltages of LR6-type batteries prepared from the cathode materials in Comparative Example 1 and Example 2 after storing at room temperature for different times. It can be seen from the figure that the open-circuit voltage of the battery prepared from the cathode material in Example 2 is significantly higher than that of the battery prepared from the cathode material in Comparative Example 1. At the same time, after storing for 15 days and 30 days respectively, the open-circuit voltages of the batteries prepared from the cathode material in Example 2 are both higher than those of the batteries prepared from the cathode material in Comparative Example 1.

[0058] Figure 2 It is a comparison chart of the open-circuit voltages of LR6-type batteries prepared from the cathode materials in Comparative Example 1 and Example 2 after storing at 60°C for different times. It can be seen from the figure that the open-circuit voltage of the battery prepared from the cathode material in Example 2 is significantly higher than that of the battery prepared from the cathode material in Comparative Example 1. At the same time, even after high-temperature storage for 1 week, 2 weeks, 3 weeks, 4 weeks, and 5 weeks respectively, the open-circuit voltages of the batteries prepared from the cathode material in Example 2 are still higher than those of the batteries prepared from the cathode material in Comparative Example 1.

[0059] Figure 3It is a comparison chart of the discharge time and the discharge time decay rate of LR6 type batteries prepared with the cathode materials in Example 2 and Comparative Example 1 after 30 days of storage at room temperature, under the mode of constant resistance continuous discharge to 0.9V at 3.9Ω. It can be seen from the chart that after 30 days of storage at room temperature, the discharge time of the battery prepared with the cathode material in Example 2 is 399.9min when continuously discharging at a constant resistance of 3.9Ω to 0.9V, which is significantly higher than that of the battery prepared with the cathode material in Comparative Example 1 (381.6min). At the same time, the decay rate is only 3.5%, which is 2.2% lower than that of Comparative Example 1.

[0060] Figure 4 It is a comparison chart of the discharge time and the discharge time decay rate of LR6 type batteries prepared with the cathode materials in Example 2 and Comparative Example 1 after 5 weeks of storage at high temperature, under the mode of constant resistance continuous discharge to 0.9V at 3.9Ω. It can be seen from the chart that after 5 weeks of storage at high temperature, the discharge time of the battery prepared with the cathode material in Example 2 is 364.2min when continuously discharging at 3.9Ω to 0.9V, which is significantly higher than that of the battery prepared with the cathode material in Comparative Example 1 (340.6min). At the same time, the decay rate is only 12.2%, which is better than that of the battery in Comparative Example 1 (15.8%).

[0061] Figure 5 It is the discharge curve of LR6 type batteries prepared with the cathode materials in Example 1, Example 2 and Example 3 after standing for 24 hours, under the mode of constant resistance continuous discharge to 0.9V at 3.9Ω. It can be seen from the chart that when the addition amount of potassium persulfate is 1%, the discharge time decreases instead. This may be because the conductivity of potassium persulfate is worse than that of potassium hydroxide, and the excessive addition reduces the active sites of manganese dioxide and the overall conductivity of the cathode.

[0062] In summary, it can be known that using potassium persulfate as the cathode additive of alkaline zinc-manganese batteries with high open circuit voltage can not only effectively increase the open circuit voltage of alkaline zinc-manganese batteries, but also oxidize part of the MnOOH generated by self-discharge into active MnO2 to participate in the discharge reaction again, reduce the cathode polarization caused by the accumulation of MnOOH and offset part of the capacity loss due to self-discharge, thereby improving the discharge performance and storage performance of alkaline zinc-manganese batteries.

[0063] The above embodiments are the preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery, characterized in that: The positive electrode additive contains potassium persulfate. The positive electrode material added with the positive electrode additive includes the following raw materials: electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate.

2. The positive electrode additive of a high open-circuit voltage alkaline zinc-manganese battery according to claim 1, characterized in that: The positive electrode material includes the following raw materials: 86 - 91 parts of electrolytic manganese dioxide, 6 - 10 parts of graphite, 0.3 - 1.0 part of calcium stearate, 0.08 - 1.0 part of potassium persulfate, and 2 - 5 parts of positive electrode electrolyte.

3. The positive electrode additive of a high open-circuit voltage alkaline zinc-manganese battery according to claim 1, characterized in that: The positive electrode material is composed of the following raw materials in parts by weight: 86 - 91 parts of electrolytic manganese dioxide, 6 - 9 parts of graphite, 0.3 part of calcium stearate, 0.08 - 1.0 part of potassium persulfate, and 2 - 5 parts of positive electrode electrolyte.

4. The positive electrode additive of a high open-circuit voltage alkaline zinc-manganese battery according to claim 1, characterized in that: The positive electrode electrolyte is a 40% wt potassium hydroxide solution.

5. The positive electrode additive of a high open-circuit voltage alkaline zinc-manganese battery according to claim 1, characterized in that: The graphite is one or several of expanded graphite, semi-expanded graphite, and flake graphite.

6. Use of a positive electrode additive for a high open-circuit voltage alkaline zinc-manganese battery according to any one of claims 2-5, characterized in that: It includes the following steps: S1. According to the parts by weight, mix electrolytic manganese dioxide, graphite, calcium stearate, and potassium persulfate and dry-mix them evenly to obtain mixture A for standby. S2. According to the parts by weight, add the positive electrode electrolyte to mixture A and stir until it is uniform to obtain mixture B for standby. S3. Press, granulate, and form a ring for mixture B to obtain the positive electrode material.

Images