A high-temperature nickel-hydrogen battery formula and preparation process

Abstract

The application provides a high-temperature nickel-hydrogen battery formula and a preparation process. The positive electrode of the high-temperature nickel-hydrogen battery comprises a base body of foamed nickel, active material of spherical nickel hydroxide, a conductive agent of cobaltous oxide, a binder of sodium carboxymethyl cellulose, an additive of zinc oxide and cerium oxide; the negative electrode comprises a base body of copper mesh, active material of hydrogen storage alloy powder, a binder of polytetrafluoroethylene emulsion, and an additive of neodymium oxide; and the electrolyte comprises sodium hydroxide, potassium hydroxide and barium hydroxide. The positive electrode, a polypropylene diaphragm and the negative electrode are wound into an electric core, a layer of polyimide film is wound outside the electric core, and then the electric core is loaded into a battery steel shell, electrolyte is injected, the battery shell is sealed, and the high-temperature nickel-hydrogen battery is obtained through charging and discharging treatment. The high-temperature nickel-hydrogen battery of the application inhibits the release of oxygen in the positive electrode by adding zinc oxide to the positive electrode, and the addition of cerium oxide can prevent the failure of the spherical nickel hydroxide to a certain extent at a high temperature of more than 50 DEG, so that the charging efficiency of the positive electrode is obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nickel-hydrogen batteries, in particular to a high-temperature nickel-hydrogen battery formula and a preparation process. BACKGROUND

[0002] A nickel-hydrogen battery is usually composed of a positive electrode, a negative electrode, a separator and an electrolyte. The positive electrode is usually a nickel electrode, which is made of foamed nickel as a substrate and is formed by electrochemical immersion. The negative electrode is made of hydrogen storage alloy powder attached to the negative electrode substrate. The separator separates the positive electrode and the negative electrode, does not allow electrons to pass through, but allows ions in the separator to transport the charges generated by the positive electrode and the negative electrode during reaction. The change of ambient temperature during the charging and discharging process has a huge impact on the performance of the battery. The specific capacity of the traditional nickel-hydrogen battery will decrease when the temperature exceeds 30℃, which will reduce the performance of the battery at high temperature. SUMMARY

[0003] In order to solve the above-mentioned deficiencies of the prior art, the purpose of the present application is to provide a high-temperature nickel-hydrogen battery formula and a preparation process to overcome the defects in the prior art.

[0004] In order to achieve the above-mentioned purpose, the present application provides a high-temperature nickel-hydrogen battery formula, which comprises a positive electrode, a negative electrode and an electrolyte. The positive electrode comprises a substrate foamed nickel, an active material cobalt-coated spherical nickel hydroxide, a conductive agent cobalt monoxide, a binder sodium carboxymethyl cellulose and additives nano-zinc oxide, calcium carbonate and cerium oxide. The negative electrode comprises a substrate copper mesh, an active material hydrogen storage alloy powder, a conductive agent graphene, a binder polytetrafluoroethylene emulsion and an additive nano-neodymium oxide. The electrolyte comprises sodium hydroxide, potassium hydroxide and barium hydroxide.

[0005] Through the above technical solution, the cobalt-coated spherical nickel hydroxide is used as the active material in the positive electrode, which can reduce the internal resistance of the battery. The addition of cobalt monoxide can dissolve and precipitate in the electrolyte, covering the surface of the spherical nickel hydroxide. After charging, CoOOH is formed. Since CoOOH has good conductivity, it can improve the conductivity between the spherical nickel hydroxide and the foamed nickel substrate, reduce the internal resistance of the battery and improve the utilization rate of the spherical nickel hydroxide. The synergistic effect of nano-zinc oxide and cobalt monoxide can improve the high-temperature discharge efficiency. The addition of calcium carbonate can improve the utilization rate of the active material and the high-temperature performance. The addition of cerium oxide can prevent the failure of the spherical nickel hydroxide to a certain extent at a higher temperature of more than 40 degrees, improve the charging efficiency of the positive electrode, and thus significantly improve the charging efficiency of the positive electrode in a high-temperature environment.

[0006] The addition of graphene in the negative electrode can increase the conductivity of the negative electrode. The addition of nano-neodymium oxide can cover the hydrogen storage alloy powder, increase the corrosion resistance of the hydrogen storage alloy powder, inhibit the increase of the internal resistance of the battery and further improve the high-temperature performance of the battery.

[0007] The polytetrafluoroethylene emulsion is a water dispersion liquid of polytetrafluoroethylene polymerized dispersion liquid concentrated to a polytetrafluoroethylene solid content of 60 wt.% and stabilized by a non-ionic surfactant.

[0008] As a further description of the high-temperature nickel-hydrogen battery formula of the present application, preferably, the weight ratio of cobalt-coated spherical nickel hydroxide, cobalt monoxide, sodium carboxymethyl cellulose, nano-zinc oxide, calcium carbonate, and cerium oxide in the positive electrode is 92:10:3:2:5:3.

[0009] As a further description of the high-temperature nickel-hydrogen battery formula of the present application, preferably, the weight ratio of hydrogen storage alloy powder, graphene, polytetrafluoroethylene emulsion, and nano-neodymium oxide in the negative electrode is 92:15:3:1.

[0010] As a further description of the high-temperature nickel-hydrogen battery formula of the present application, preferably, the hydrogen storage alloy powder comprises 50 wt.% nickel, 18 wt.% cobalt, 5 wt.% manganese, 8 wt.% aluminum, 10 wt.% magnesium, and 9 wt.% cerium.

[0011] By the above technical solution, cerium can store hydrogen, has good corrosion resistance, and has a longer service life, but has a lower capacity and slow activation. The addition of 9% cerium and the use of 50% nickel are beneficial to improve the hydrogen evolution catalytic activity and electrochemical stability of the negative electrode. The addition of aluminum and manganese can improve the hydrogen storage performance. The addition of manganese can increase the capacity of the negative electrode sheet, thereby increasing the capacity of the nickel-hydrogen battery. The addition of aluminum can form a dense aluminum oxide film, thereby improving the corrosion resistance of the hydrogen storage alloy powder. When the hydrogen storage alloy powder is attached to the negative electrode substrate, it can have better corrosion resistance and is not easy to powder, thereby improving the structural stability of the negative electrode sheet and the cycle life of the nickel-hydrogen battery. The addition of magnesium can adjust the equilibrium pressure of the hydrogen storage alloy powder during hydrogen adsorption / desorption, and adjust the hydrogen storage capacity and corrosion resistance of the hydrogen storage alloy powder. The addition of nano-neodymium oxide in the negative electrode can improve the strength and corrosion resistance of the magnesium and aluminum alloy in a high-temperature environment.

[0012] As a further description of the high-temperature nickel-hydrogen battery formula of the present application, preferably, the mass percentage concentrations of sodium hydroxide, potassium hydroxide, and barium hydroxide in the electrolyte are 50-70%, 10-20%, and 10-15%, respectively.

[0013] As a further description of the high-temperature nickel-hydrogen battery formula of the present application, preferably, the concentration of the electrolyte is controlled between 6.5-10 mol / L.

[0014] In order to achieve another object of the present application, the present application further provides a preparation process of a high-temperature nickel-hydrogen battery, which comprises the following steps:

[0015] Step 1): mix cobalt-coated spherical nickel hydroxide, cobalt suboxide, sodium carboxymethyl cellulose, nano-zinc oxide, calcium carbonate and cerium oxide uniformly to form a first mixture, fill the first mixture into a positive electrode substrate foam nickel through mechanical mixing, then roll and cut to obtain a positive electrode of a nickel-hydrogen battery.

[0016] Step 2): mix hydrogen storage alloy powder, graphene and nano-neodymium oxide uniformly to form a second mixture, roll the second mixture onto a negative electrode substrate copper mesh, immerse the second mixture on the surface of the negative electrode substrate copper mesh in polytetrafluoroethylene emulsion, then dry and cut to obtain a negative electrode of a nickel-hydrogen battery.

[0017] Step 3): dissolve sodium hydroxide, potassium hydroxide and barium hydroxide in pure water to obtain an electrolyte.

[0018] Step 4): roll the positive electrode, a polypropylene separator and the negative electrode into an electric core, wrap a layer of polyimide film outside the electric core, then put the electric core into a battery steel shell, inject the electrolyte, seal the battery shell, and then perform charge and discharge treatment to obtain a high-temperature nickel-hydrogen battery.

[0019] As a further description of the preparation process of the application, preferably, the weight ratio of cobalt-coated spherical nickel hydroxide, cobalt suboxide, sodium carboxymethyl cellulose, nano-zinc oxide, calcium carbonate and cerium oxide is 92:10:3:2:5:3; the weight ratio of hydrogen storage alloy powder, graphene, polytetrafluoroethylene emulsion and nano-neodymium oxide is 92:15:3:1; the mass percentage concentrations of sodium hydroxide, potassium hydroxide and barium hydroxide in the electrolyte are 50-70%, 10-20% and 10-15% respectively; and the concentration of the electrolyte is controlled between 6.5-10 mol / L.

[0020] As a further description of the preparation process of the application, preferably, the hydrogen storage alloy powder comprises 50wt.% nickel, 18wt.% cobalt, 5wt.% manganese, 8wt.% aluminum, 10wt.% magnesium and 9wt.% cerium.

[0021] Advantages of the application:

[0022] 1. The high-temperature nickel-hydrogen battery formula of the application, in the positive electrode, the active material spherical nickel hydroxide is ordinary spherical nickel hydroxide, the cost is lower, at the same time, without changing the structure of the existing nickel-hydrogen battery, adding cobalt oxide, cobalt oxide dissolves in electrolyte, precipitates and covers the surface of spherical nickel hydroxide, forms CoOOH after charging, because CoOOH has good conductivity, can improve the conductivity between spherical nickel hydroxide and nickel foam matrix, reduce the internal resistance of the battery, improve the utilization rate of spherical nickel hydroxide. Add nano zinc oxide and cobalt oxide to improve the high-temperature discharge efficiency. Adding calcium carbonate can improve the utilization rate of active material and high-temperature performance. Adding cerium oxide can prevent the failure of spherical nickel hydroxide to a certain extent at a higher temperature of more than 40 degrees, improve the charging efficiency of the positive electrode, so that the charging efficiency of the positive electrode in the high-temperature environment is obviously improved. Adding graphene in the negative electrode can increase the conductivity of the negative electrode. Adding nano neodymium oxide can cover the hydrogen storage alloy powder and increase the corrosion resistance of the hydrogen storage alloy powder to inhibit the increase of the internal resistance of the battery and further improve the high-temperature performance of the battery. By increasing the ratio of Na and reducing the ratio of K in the electrolyte, the high-temperature performance of the electrolyte is improved, and the characteristics of NA are beneficial to high temperature.

[0023] 2. The preparation process of the high-temperature nickel-hydrogen battery of the application is that the positive electrode, polypropylene diaphragm and negative electrode are wound into an electric core, and then a polyimide film is wound outside the electric core, which has good high-temperature resistance, heat insulation and heat reflection materials. Using the polyimide film can effectively reflect the heat energy conducted to the battery to the external air, thereby avoiding the temperature rise of the battery due to the excessively high external environment, and reducing the service life of the battery. DETAILED DESCRIPTION

[0024] In order to further understand the structure, features and other purposes of the application, the preferred embodiments are described in detail as follows, and the embodiments are only used to illustrate the technical solutions of the application, not to limit the application.

[0025] Example 1: Preparation of high-temperature nickel-hydrogen battery.

[0026] Preparation of positive electrode:

[0027] Cobalt-coated spherical nickel hydroxide, cobalt oxide, sodium carboxymethyl cellulose, nano zinc oxide, calcium carbonate and cerium oxide are mixed in a weight ratio of 92:10:3:2:5:3 to form a first mixture.

[0028] The first mixture is filled into the positive electrode matrix of nickel foam by mechanical mixing, and then rolled and cut to obtain the positive electrode of the nickel-hydrogen battery. The drying temperature is preferably 40-80 DEG C.

[0029] Preparation of negative electrode:

[0030] Prepare hydrogen storage alloy powder, graphene, polytetrafluoroethylene emulsion and nanometer neodymium oxide in a weight ratio of 92:15:3:1. Among them, the hydrogen storage alloy powder includes: 50wt.% nickel, 18wt.% cobalt, 5wt.% manganese, 8wt.% aluminum, 10wt.% magnesium, 9wt.% cerium.

[0031] Mix the hydrogen storage alloy powder, graphene, nanometer neodymium oxide and 30% polytetrafluoroethylene emulsion uniformly, and roll onto the negative electrode substrate copper mesh. The remaining 70% polytetrafluoroethylene emulsion is evenly infiltrated onto the surface of the negative electrode substrate. After the polytetrafluoroethylene emulsion is fully infiltrated, roll to the required thickness, dry, and cut to the required size to obtain the negative electrode of the nickel-hydrogen battery.

[0032] The polytetrafluoroethylene emulsion is a dispersion liquid after polymerization of polytetrafluoroethylene, concentrated to a polytetrafluoroethylene solid content of 60wt.% and a water dispersion liquid stabilized by a non-ionic surfactant. The polytetrafluoroethylene emulsion has excellent chemical stability and corrosion resistance. The addition of polytetrafluoroethylene emulsion to the negative electrode can improve the chemical stability of the negative electrode, thereby improving the stability and chemical corrosion resistance of the prepared negative electrode, and further improving the cycle life and performance of the nickel-hydrogen battery.

[0033] Preparation of electrolyte:

[0034] Dissolve sodium hydroxide, potassium hydroxide and barium hydroxide in pure water to obtain an electrolyte. Among them, the mass percentage concentration of sodium hydroxide, potassium hydroxide and barium hydroxide in the electrolyte is 50-70%, 10-20% and 10-15% respectively. The concentration of the electrolyte is preferably controlled at 8mol / L.

[0035] Battery assembly:

[0036] Winding the positive electrode, polypropylene separator and negative electrode into an electric core, winding a layer of polyimide film outside the electric core, then putting it into a battery steel shell, injecting the electrolyte, sealing the battery shell, and after charging and discharging treatment, obtaining a high-temperature nickel-hydrogen battery.

[0037] Comparative Example 1:

[0038] Prepare a nickel-hydrogen battery according to the method described in Example 1, except that the positive electrode does not add cerium oxide.

[0039] Comparative Example 2:

[0040] Prepare a nickel-hydrogen battery according to the method described in Example 1, except that the negative electrode does not add nanometer neodymium oxide.

[0041] Comparative Example 3:

[0042] Prepare a nickel-hydrogen battery according to the method described in Example 1, except that no polyimide film is wound outside the electric core in the battery assembly step.

[0043] Comparative Example 4:

[0044] Ordinary nickel-hydrogen battery in prior art.

[0045] Comparative Example 5:

[0046] The nickel-hydrogen battery was prepared according to the method described in Example 1, except that the amount of potassium hydroxide (20%) and barium hydroxide (10%) added in the electrolyte was unchanged, and the amount of sodium hydroxide added was changed (70%, 60%, 50%, 40%, 30%, 20%, and 10% were used for comparative tests, respectively).

[0047] Performance comparison:

[0048] Method for testing the charge-discharge efficiency of the nickel-hydrogen battery at different temperatures:

[0049] The nickel-hydrogen battery was placed at 40°C, 50°C, 60°C, 70°C, and 80°C for 8 hours, so that the temperature of the nickel-hydrogen battery was the same as the temperature of the environment. Then, the battery was charged at a charging current of 0.1C for 6 hours, and discharged at a discharging current of 0.2C to a cutoff voltage of 1.0V. The discharge capacity of the battery was calculated and compared with the discharge capacity of the nickel-hydrogen battery at room temperature, to obtain the charge efficiency of the nickel-hydrogen battery at high temperature.

[0050] (1) The nickel-hydrogen batteries obtained in Example 1 and Comparative Examples 1-4 were tested respectively, and the average value of the test results was taken. The charge efficiency of the nickel-hydrogen batteries obtained in each example and comparative example at high temperature (i.e. the ratio of the discharge capacity of the nickel-hydrogen battery to the charging capacity, expressed in percentage) is shown in Table 1:

[0051] Table 1

[0052] 40℃ 50℃ 60℃ 70℃ 80℃ Example 1 98％ 96％ 93.5％ 90％ 86％ Comparative Example 1 94％ 91％ 87％ 82％ 75％ Comparative Example 2 95％ 93％ 90.5％ 85.5％ 80％ Comparative Example 3 98％ 95.5％ 92％ 89％ 84％ Comparative Example 4 80％ 68％ 55％ 38％ 20％

[0053] As can be seen from Table 1, the charge efficiency of the ordinary nickel-hydrogen battery (i.e. Comparative Example 4) decreases sharply with the increase of the environmental temperature, and it is basically unable to be used at an environmental temperature of 80°C.

[0054] The nickel-hydrogen battery prepared in Example 1 has a significant improvement in high-temperature performance compared to the ordinary nickel-hydrogen battery of Comparative Example 4. At a high-temperature environment of 80°C, it can still achieve a charge efficiency of more than 80% at room temperature.

[0055] As can be seen from Comparative Examples 1 and 2, cerium oxide or nanometer neodymium oxide has a certain influence on the high-temperature performance of the nickel-hydrogen battery. In Comparative Example 2, the influence of not adding nanometer neodymium oxide to the negative electrode on the nickel-hydrogen battery at high temperature is significantly less than the influence of not adding cerium oxide to the positive electrode on the nickel-hydrogen battery at high temperature in Comparative Example 1.

[0056] From the comparative example 3, it can be seen that whether the battery cell is wrapped with polyimide film or not has influence on the performance of the nickel-hydrogen battery at temperature less than 60℃, which shows that the polyimide film has obvious heat insulation effect at temperature less than 60℃.

[0057] (2) The nickel-hydrogen battery obtained from the comparative example 5 was tested, and the charging efficiency of the obtained nickel-hydrogen battery at high temperature (i.e. the ratio of the discharge capacity of the nickel-hydrogen battery to the charging capacity, expressed in percentage) was obtained, as shown in Table 2:

[0058] Table 2

[0059]

[0060] From Table 2, it can be seen that increasing the ratio of Na in the electrolyte is helpful to the high-temperature characteristics of the nickel-hydrogen battery.

[0061] Therefore, adding cerium oxide to the positive electrode or adding nanometer neodymium oxide to the negative electrode can both significantly improve the charging efficiency of the nickel-hydrogen battery at high temperature. In particular, adding cerium oxide to the positive electrode can prevent the failure of spherical nickel hydroxide to a certain extent at a higher temperature greater than 40 degrees, thereby improving the charging efficiency of the positive electrode, so that the charging efficiency of the positive electrode at high temperature is significantly improved. Increasing the ratio of Na in the electrolyte is also beneficial to the high-temperature characteristics.

[0062] It should be stated that the above invention content and specific embodiments are intended to prove the practical application of the technical solutions provided by the present application, and should not be interpreted as a limitation on the protection scope of the present application. Those skilled in the art can make various modifications, equivalent replacements or improvements within the spirit and principles of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A high temperature nickel-hydrogen battery formulation comprising a positive electrode, a negative electrode and an electrolyte, characterized in that, The positive electrode comprises a base foam nickel, active cobalt-coated spherical nickel hydroxide, conductive cobalt oxide, binder sodium carboxymethyl cellulose and additives nano zinc oxide, calcium carbonate and cerium oxide; The negative electrode comprises a base copper mesh, active hydrogen storage alloy powder, conductive graphene, binder polytetrafluoroethylene emulsion and additive nano neodymium oxide; the hydrogen storage alloy powder comprises 50wt.% nickel, 18wt.% cobalt, 5wt.% manganese, 8wt.% aluminum, 10wt.% magnesium and 9wt.% cerium; The electrolyte comprises sodium hydroxide, potassium hydroxide and barium hydroxide; the mass percentage of sodium hydroxide, potassium hydroxide and barium hydroxide in the electrolyte is 50-70%, 10-20% and 10-15% respectively; the concentration of the electrolyte is controlled at 8mol / L.

2. The high temperature nickel-hydrogen battery formulation of claim 1, wherein, The weight ratio of cobalt-coated spherical nickel hydroxide, cobalt oxide, sodium carboxymethyl cellulose, nano zinc oxide, calcium carbonate and cerium oxide in the positive electrode is 92:10:3:2:5:

3.

3. The high temperature nickel-hydrogen battery formulation of claim 1, wherein, The weight ratio of hydrogen storage alloy powder, graphene, polytetrafluoroethylene emulsion and nano neodymium oxide in the negative electrode is 92:15:3:

1.

4. A manufacturing process for a high-temperature nickel-metal hydride battery as described in any one of claims 1-3, characterized in that, The preparation process comprises the following steps: Step 1): uniformly mix cobalt-coated spherical nickel hydroxide, cobalt oxide, sodium carboxymethyl cellulose, nano zinc oxide, calcium carbonate and cerium oxide to form a first mixture, fill the first mixture into the positive electrode base foam nickel by mechanical mixing, then roll and cut to obtain the positive electrode of the nickel-hydrogen battery; Step 2): uniformly mix hydrogen storage alloy powder, graphene and nano neodymium oxide to form a second mixture, roll the second mixture onto the negative electrode base copper mesh, soak the second mixture on the surface of the negative electrode base copper mesh in polytetrafluoroethylene emulsion, then dry and cut to obtain the negative electrode of the nickel-hydrogen battery; the hydrogen storage alloy powder comprises 50wt.% nickel, 18wt.% cobalt, 5wt.% manganese, 8wt.% aluminum, 10wt.% magnesium and 9wt.% cerium; Step 3): dissolve sodium hydroxide, potassium hydroxide and barium hydroxide in pure water to obtain an electrolyte; the mass percentage of sodium hydroxide, potassium hydroxide and barium hydroxide in the electrolyte is 50-70%, 10-20% and 10-15% respectively; the concentration of the electrolyte is controlled at 8mol / L; Step 4): roll the positive electrode, polypropylene separator and negative electrode into an electric core, wrap a layer of polyimide film outside the electric core, then put the electric core into a battery steel shell, inject the electrolyte, seal the battery shell and perform charge and discharge treatment to obtain a high-temperature nickel-hydrogen battery.

5. The preparation process according to claim 4, wherein The weight ratio of cobalt-coated spherical nickel hydroxide, cobalt oxide, sodium carboxymethyl cellulose, nano zinc oxide, calcium carbonate and cerium oxide is 92:10:3:2:5:3; the weight ratio of hydrogen storage alloy powder, graphene, polytetrafluoroethylene emulsion and nano neodymium oxide is 92:15:3:1.

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