High-energy-density nickel-metal hydride battery and preparation method thereof

Abstract

The invention relates to the field of aqueous batteries, in particular to a high-energy-density nickel-metal hydride battery and a preparation method thereof, an electrolyte of the nickel-metal hydride battery is a tetramethylammonium hydroxide aqueous electrolyte, a negative electrode material is Mg55Pd4Ni41, and a positive electrode material is Ni (OH) 2. An electrolyte of the battery is a tetramethylammonium hydroxide aqueous electrolyte, a negative electrode material is a magnesium-based hydrogen storage alloy electrode material with high magnesium content, and tetramethylammonium hydroxide is used as the electrolyte, so that the self-discharge of the nickel-metal hydride battery can be reduced, the discharge capacity of the electrode material is increased, and the energy density of the nickel-metal hydride battery is improved.

Description

Technical Field

[0001] The present invention relates to the field of aqueous batteries, and in particular to a high energy density nickel-hydrogen battery and a preparation method thereof. Background Art

[0002] Nickel-metal hydride batteries have the advantages of high safety, no pollution, resistance to overcharge and over-discharge, and a wide operating temperature range. They are still widely used in various electronic devices, especially in the field of power batteries. However, their energy density is lower than that of lithium-ion batteries, which greatly limits them in market competition. Therefore, improving the energy density of nickel-metal hydride batteries has become the top priority for improving the performance of nickel-metal hydride batteries.

[0003] Improving the discharge capacity of the electrode is an effective way to increase the energy density of the battery. As the negative electrode material of commercial nickel-hydrogen batteries, the actual electrochemical capacity of the AB5 alloy electrode is between 320 and 350 mAh / g, which is close to its theoretical electrochemical capacity (372 mAh / g), and there is very limited room for improvement. Magnesium-based alloys have relatively high electrochemical capacity, with an actual discharge capacity of more than 500 mAh / g. As negative electrode materials for nickel-hydrogen batteries, they will significantly increase the energy density of nickel-hydrogen batteries.

[0004] However, nickel-hydrogen batteries use alkaline aqueous electrolytes, which will corrode the magnesium metal elements in magnesium-based alloys, consume the amount of alloy active substances, and cause the capacity of the alloy electrode to decay rapidly. Electrolyte modification can improve the electrochemical properties of alloy electrodes economically and effectively, so many studies have attempted to improve the performance of nickel-hydrogen batteries through electrolyte modification. The exploration and modification of nickel-hydrogen battery electrolytes has gone through a long process, but electrolyte modification has not brought significant improvements to the performance of nickel-hydrogen batteries. Currently, commercial nickel-hydrogen batteries still use KOH solution as the electrolyte. There is no doubt that the active metal elements in the metal hydride electrode cannot completely get rid of the corrosion of KOH solution.

[0005] Therefore, it is necessary and of practical significance to develop a new solution that is less corrosive to metal elements as the electrolyte of nickel-hydrogen batteries. This will provide new ideas for improving battery energy density and life, especially for nickel-hydrogen batteries with magnesium-based alloys as negative electrodes, which are very easy to corrode in alkaline electrolytes. Summary of the invention

[0006] The object of the present invention is to provide a high energy density nickel-hydrogen battery in view of the above-mentioned problems. The electrolyte of the battery is a tetramethylammonium hydroxide aqueous electrolyte, and the negative electrode material is a magnesium-based hydrogen storage alloy electrode material with a high magnesium content. The present invention uses tetramethylammonium hydroxide as the electrolyte to reduce the self-discharge of the nickel-hydrogen battery, increase the discharge capacity of the electrode material, and thus improve the energy density of the nickel-hydrogen battery.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A high energy density nickel-hydrogen battery, characterized in that the electrolyte of the nickel-hydrogen battery is a tetramethylammonium hydroxide aqueous electrolyte, and the negative electrode material is Mg 55 Pd4Ni 41 , the positive electrode material is Ni(OH)2.

[0009] Preferably, the electrolyte is a tetramethylammonium hydroxide solution with a molar concentration of 4.5 mol / L.

[0010] Furthermore, the preparation method of the tetramethylammonium hydroxide solution comprises the following steps:

[0011] (1) calculating the required mass of tetramethylammonium hydroxide according to the molar concentration of the tetramethylammonium hydroxide solution to be prepared, and weighing the corresponding mass of tetramethylammonium hydroxide;

[0012] (2) adding water to dissolve the weighed tetramethylammonium hydroxide to obtain solution A;

[0013] (3) draining solution A obtained in step (2) into a volumetric flask;

[0014] (4) Pour distilled water into the volumetric flask to the mark, cover the flask with the stopper, and shake well to obtain tetramethylammonium hydroxide solution.

[0015] Furthermore, the Mg 55 Pd4Ni 41 The method for preparing the negative electrode material comprises the following steps:

[0016] (1) Press Mg 55 Pd4Ni 41 Weigh Mg, Pd and Ni powder materials in a stoichiometric ratio and mix them evenly to obtain mixed powder A;

[0017] (2) placing the mixed powder in a ball mill, introducing argon gas into the ball mill and performing ball milling;

[0018] (3) After the ball milling, Mg was obtained in a glove box with an argon atmosphere. 55 Pd4Ni 41 alloy powder;

[0019] (4) The Mg obtained in step (3) 55 Pd4Ni 41 The alloy powder and Ni powder were uniformly mixed in a mass ratio of 1:4 to obtain mixed powder B;

[0020] (5) The mixed powder B is placed in a mold and cold pressed into a sheet, which is the Mg 55 Pd4Ni41 Negative electrode material.

[0021] Preferably, during the ball milling, the ball-to-material ratio of the grinding balls to the mixed powder is 60:1, and the diameter of the grinding balls is 10 mm.

[0022] Preferably, the ball milling speed is 450 rpm; the total ball milling time is 60 hours, wherein each ball milling is 30 minutes and then rested for 15 minutes, and the rotation direction of the ball mill is reversed after each rest. The specific operation is: at a speed of 450 rpm, forward rotation for 30 minutes, rest for 15 minutes, then reverse rotation for 30 minutes, rest for 15 minutes; in this cycle, a total of 60 forward rotations and 60 reverse rotations are required, and the total forward and reverse rotation time is 60 hours.

[0023] Preferably, the mold has a diameter of 10 mm, and the mixed powder B is cold-pressed into a disc with a diameter of 10 mm.

[0024] Preferably, the cold pressing pressure is 15 to 30 MPa.

[0025] In addition, the method for preparing a high energy density nickel-hydrogen battery comprises the following steps:

[0026] (1) Pressing the positive electrode material and the negative electrode material into sheets respectively;

[0027] (2) placing the positive electrode material and the negative electrode material into the electrolytic cell in sequence;

[0028] (3) injecting tetramethylammonium hydroxide aqueous electrolyte into the electrolytic cell and sealing it to obtain the high energy density nickel-hydrogen battery.

[0029] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0030] The high energy density nickel-hydrogen battery provided by the present invention uses tetramethylammonium hydroxide as an aqueous electrolyte and a magnesium-based hydrogen storage alloy electrode material Mg with a high magnesium content. 55 Pd4Ni4 is the negative electrode material. Compared with the traditional KOH electrolyte, the tetramethylammonium hydroxide aqueous electrolyte has a lower corrosion rate on magnesium elements, which can improve the electrochemical cycle stability of the magnesium-based alloy electrode. In addition, the present invention uses tetramethylammonium hydroxide as the electrolyte to reduce the self-discharge of the nickel-hydrogen battery, increase the discharge capacity of the electrode material, and thus improve the energy density of the nickel-hydrogen battery. Laboratory data show that the discharge specific energy of the nickel-hydrogen battery of the present invention exceeds 210Wh / kg. The Mg 55 Pd4Ni 41 The / Ni(OH)2 full battery has a discharge specific energy of 212.2Wh / kg in 4.5M tetramethylammonium hydroxide electrolyte, and still has a discharge specific energy of 187.2Wh / kg after 15 cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Mg 55 Pd4Ni 41 XRD patterns of the alloy.

[0032] Figure 2 Mg 55 Pd4Ni 41 HRTEM images and selected area electron diffraction patterns of the alloy.

[0033] Figure 3 Mg 55 Pd4Ni 41 Tafel curves of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte.

[0034] Figure 4 Mg 55 Pd4Ni 41 CV curves of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte. (a) is the CV curve in 6M KOH, and (b) is the CV curve in 4.5M tetramethylammonium hydroxide aqueous electrolyte.

[0035] Figure 5 Mg 55 Pd4Ni 41 Comparison of the cycling stability of the alloy electrode in 6M KOH aqueous electrolyte and 4.5M tetramethylammonium hydroxide aqueous electrolyte.

[0036] Figure 6 Mg 55 Pd4Ni 41 XRD curve, TG curve and SEM image of the alloy electrode after 10 cycles in 6M KOH and 4.5M tetramethylammonium hydroxide aqueous electrolyte. Among them, (a) is the XRD curve; (b) is the TG curve; (c) is the Mg 55 Pd4Ni 41 Alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte; (d) Mg 55 Pd4Ni 41 SEM images of the alloy electrode after 10 cycles in 6MKOH.

[0037] Figure 7 Mg 55 Pd4Ni 41 Charging curves, standing process and the relationship between standing time and discharge capacity of Ni(OH)2 full battery in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte (the amount of active material is calculated by Mg55 Pd4Ni 41 Calculation of alloy mass).

[0038] Figure 8 Mg 55 Pd4Ni 41 Charge and discharge curves of the full Ni(OH)2 cell in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte (the amount of active material is calculated based on Mg 55 Pd4Ni 41 (calculated as the sum of the masses of the alloy and Ni(OH)2).

[0039] Fig. 9 Mg 55 Pd4Ni 41 Cyclic discharge specific energy diagram of / Ni(OH)2 full cell in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte. DETAILED DESCRIPTION

[0040] The present invention provides a high energy density nickel-hydrogen battery, wherein the electrolyte of the nickel-hydrogen battery is a tetramethylammonium hydroxide aqueous electrolyte, and the negative electrode material is Mg 55 Pd4Ni 41 , the positive electrode material is Ni(OH)2.

[0041] Wherein, the electrolyte is a tetramethylammonium hydroxide solution with a molar concentration of 4.5 mol / L, and the preparation method of the tetramethylammonium hydroxide solution comprises the following steps:

[0042] (1) Calculate the mass of tetramethylammonium hydroxide required to prepare a tetramethylammonium hydroxide solution with a molar concentration of 4.5 mol / L, and weigh the corresponding mass of tetramethylammonium hydroxide;

[0043] (2) adding water to dissolve the weighed tetramethylammonium hydroxide to obtain solution A;

[0044] (3) draining solution A obtained in step (2) into a volumetric flask;

[0045] (4) Pour distilled water into the volumetric flask to the mark, cover the bottle with a stopper, and shake well to obtain the tetramethylammonium hydroxide solution.

[0046] Furthermore, the Mg 55 Pd4Ni 41 The method for preparing the negative electrode material comprises the following steps:

[0047] (1) Press Mg 55 Pd4Ni 41 Weigh Mg, Pd and Ni powder materials in a stoichiometric ratio and mix them evenly to obtain mixed powder A;

[0048] (2) Place the mixed powder in a ball mill, add grinding balls at a ball-to-material ratio of 60:1, the diameter of the grinding balls is 10 mm, then introduce argon gas into the ball mill and perform ball milling; the ball mill speed is 450 rpm; the total ball milling time is 60 hours, wherein each ball milling is 30 minutes and then rested for 15 minutes, and the rotation direction of the ball mill is reversed after each rest. The specific operation is: at a speed of 450 rpm, rotate forward for 30 minutes, rest for 15 minutes, then reverse for 30 minutes, and rest for 15 minutes; repeat this cycle, a total of 60 times of forward rotation and 60 times of reverse rotation, and the total time of forward rotation and reverse rotation is 60 hours;

[0049] (3) After ball milling, Mg was obtained in an argon atmosphere. 55 Pd4Ni 41 alloy powder;

[0050] (4) Mg obtained in step (3) 55 Pd4Ni 41 The alloy powder and Ni powder were uniformly mixed in a mass ratio of 1:4 to obtain mixed powder B;

[0051] (5) The mixed powder B is placed in a mold with a diameter of 10 mm and cold pressed at a pressure of 15 to 30 MPa into a 10 mm diameter disc, which is the Mg 55 Pd4Ni 41 Negative electrode material.

[0052] Furthermore, the method for preparing the high energy density nickel-hydrogen battery comprises the following steps:

[0053] (1) Pressing the positive electrode material and the negative electrode material into sheets respectively;

[0054] (2) placing the positive electrode material and the negative electrode material into the electrolytic cell in sequence;

[0055] (3) injecting tetramethylammonium hydroxide aqueous electrolyte into the electrolytic cell and sealing it to obtain the high energy density nickel-hydrogen battery.

[0056] In order to express the present invention more clearly, the present invention is further described below through specific examples.

[0057] Example 1

[0058] In this embodiment, a tetramethylammonium hydroxide solution with a molar concentration of 4.5 mol / L is prepared, and the following steps are included to form a 4.5 M tetramethylammonium hydroxide aqueous electrolyte:

[0059] (1) Calculate the mass of tetramethylammonium hydroxide according to the concentration of 4.5 mol / L, and weigh the corresponding mass of tetramethylammonium hydroxide;

[0060] (2) Place the weighed tetramethylammonium hydroxide in a beaker and add water to dissolve it to obtain solution A;

[0061] (3) Drain solution A in the beaker into a volumetric flask, wash the beaker twice, and drain the washing solution into the volumetric flask;

[0062] (4) Pour distilled water into the volumetric flask to the mark, cover the flask with a stopper, and shake well to obtain the 4.5 M tetramethylammonium hydroxide aqueous electrolyte.

[0063] Comparative Example 1

[0064] In this comparative example, a KOH electrolyte having a molar concentration of 6 M was prepared using the same method as in Example 1.

[0065] Example 2

[0066] In this embodiment, the Mg 55 Pd4Ni 41 The negative electrode material, the specific preparation method comprises the following steps:

[0067] (1) Press Mg 55 Pd4Ni 41 Weigh Mg, Pd and Ni powder materials in a stoichiometric ratio and mix them evenly to obtain mixed powder A;

[0068] (2) Mixed powder A is placed in a planetary ball mill, and grinding balls are added at a ball-to-material ratio of 60:1. The diameter of the grinding balls is 10 mm. Argon gas is then introduced into the ball mill, and the ball mill is then fixed on the planetary ball mill. The ball mill speed is set to 450 rpm, and the ball mill rotates forward for 30 min, rests for 15 min, reverses for 30 min, and rests for 15 min. This cycle is repeated for a total of 60 forward rotations and 60 reverse rotations. The total time for the forward and reverse rotations is 60 hours.

[0069] (3) After the ball milling, Mg was obtained in a glove box with an argon atmosphere. 55 Pd4Ni 41 Negative electrode material alloy powder;

[0070] (4) The Mg obtained in step (3) 55 Pd4Ni 41 The negative electrode material alloy powder and Ni powder are uniformly mixed in a mass ratio of 1:4 to obtain mixed powder B. Adding Ni powder in this step can help Mg 55 Pd4Ni 41 The alloy powder is pressed into non-breakable electrode sheets, which can also serve as a conductor.

[0071] (5) The mixed powder B is placed in a mold with a diameter of 10 mm and pressed into a 10 mm diameter disc at a pressure of 15 MPa or 30 MPa to obtain a flake-shaped Mg55 Pd4Ni 41 Negative electrode material.

[0072] In addition, the tableting pressure can also be 30 MPa or can be selected between 15 and 30 MPa. Experiments have shown that the mixed powder B can be pressed into tablets with basically the same performance. This embodiment preferably uses a pressure of 15 MPa for tableting.

[0073] The obtained Mg 55 Pd4Ni 41 The negative electrode material undergoes structural testing, and the test results are as follows: Figure 1-2 shown.

[0074] Figure 1 Mg 55 Pd4Ni 41 The XRD spectrum of the alloy shows that there is no obvious crystal characteristic peak on the XRD curve, indicating that the obtained Mg 55 Pd4Ni 41 The alloy has an amorphous structure or a nanocrystalline structure.

[0075] Figure 2 Mg 55 Pd4Ni 41 HRTEM images and selected area electron diffraction patterns of the alloy. Figure 2 The results show that Mg 55 Pd4Ni 41 The structure of the alloy consists of an amorphous phase and a Mg2Ni nanocrystalline phase.

[0076] The obtained disc was coated with nickel foam on both sides and then connected to the tabs at a pressure of 2 MPa to prepare a test electrode.

[0077] Performance Test:

[0078] In Example 3, Mg 55 Pd4Ni 41 The test electrodes made of negative electrode materials were tested in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte respectively. The test results are shown in Figure 3-6 shown.

[0079] Figure 3 Mg 55 Pd4Ni 41 The Tafel curves of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH aqueous electrolyte characterize the corrosion rate of the electrolyte on the alloy electrode. Figure 3 The curve in Mg 55 Pd4Ni 41The corrosion potential of the test electrode made of the negative electrode material in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte is -0.64V and -0.69V respectively, which means that the corrosion potential of the test electrode is shifted by 50mV when using 4.5M tetramethylammonium hydroxide aqueous electrolyte. As we all know, the more positive the corrosion potential, the better the corrosion resistance of the material; conversely, the worse the corrosion resistance. This result shows that the corrosion rate of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte is lower than that in 6M KOH electrolyte.

[0080] Figure 4 Mg 55 Pd4Ni 41 CV curves of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte and 6M KOH electrolyte. Where (a) is Mg 55 Pd4Ni 41 The cyclic CV curve of the alloy electrode in 6M KOH electrolyte shows that as the number of cycles increases, the Mg 55 Pd4Ni 41 The redox peak of the alloy electrode in 6M KOH electrolyte decays rapidly, indicating that its electrochemical capacity decays rapidly; (b) is Mg 55 Pd4Ni 41 The cyclic CV curve of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte shows that as the number of cycles increases, the Mg 55 Pd4Ni 41 The redox peak of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte is very stable, with no obvious downward trend. Figure 4 It can be seen that the electrolyte can affect the electrochemical properties of the negative electrode of the nickel-hydrogen battery, and Mg 55 Pd4Ni 41 The alloy electrode has good cycling stability in 4.5M tetramethylammonium hydroxide aqueous electrolyte.

[0081] Figure 5 Mg 55 Pd4Ni 41 Comparison of the cycling stability of the alloy electrode in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte. Figure 5 It can be clearly seen that Mg 55 Pd4Ni 41 The cycling stability of the alloy electrode in 4.5M tetramethylammonium hydroxide electrolyte is higher than that in 6M KOH. After 60 cycles, Mg 55 Pd4Ni 41The discharge specific capacity of the alloy electrode in 4.5M tetramethylammonium hydroxide electrolyte is 366.4mAh / g, while the discharge specific capacity in 6M KOH electrolyte is only 246.4mAh / g.

[0082] Figure 6 Mg 55 Pd4Ni 41 XRD curves, TG curves and SEM images of the alloy electrode after 10 cycles in 6M KOH and 4.5M tetramethylammonium hydroxide aqueous electrolyte.

[0083] Where (a) is Mg 55 Pd4Ni 41 XRD curve of the alloy electrode after 10 cycles in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide aqueous electrolyte. It can be seen from the XRD curve that Mg 55 Pd4Ni 41 A strong Mg(OH)2 diffraction peak appeared on the XRD curve of the alloy electrode after 10 cycles in 6M KOH electrolyte, while the Mg(OH)2 diffraction peak in 4.5M tetramethylammonium hydroxide aqueous electrolyte was relatively weak. 55 Pd4Ni 41 The TG curve of the alloy electrode (b) shows that there is a weight loss at 310℃, which is the decomposition of Mg(OH)2. 55 Pd4Ni 41 The weight loss rates of the alloy electrode after 10 cycles in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte were 3.83% and 1.21%, respectively, and the corresponding Mg loss rates were 17.45% and 5.21%, respectively.

[0084] (c) is Mg 55 Pd4Ni 41 SEM image of the alloy electrode after 10 cycles in 4.5M tetramethylammonium hydroxide aqueous electrolyte. It can be clearly seen from Figure (c) that the Mg 55 Pd4Ni 41 There is only a small amount of granular Mg(OH)2 on the alloy surface. However, after 10 cycles in 6M KOH electrolyte, the Mg 55 Pd4Ni 41 Many flake-like Mg(OH)2 are generated on the alloy surface.

[0085] The above results all prove that Mg 55 Pd4Ni 41 The corrosion rate of the alloy electrode in 4.5M tetramethylammonium hydroxide aqueous electrolyte is significantly lower than that in 6M KOH electrolyte.

[0086] Embodiment 3:

[0087] This example prepares a high energy density nickel-hydrogen battery (called Mg 55 Pd4Ni 41 / Ni(OH)2 full battery), the preparation method comprises the following steps:

[0088] (1) Pressing the positive electrode material and the negative electrode material into sheets respectively;

[0089] (2) loading the positive electrode material and the negative electrode material into the electrolytic cell in sequence;

[0090] (3) injecting tetramethylammonium hydroxide aqueous electrolyte into the electrolytic cell and sealing it to obtain the high energy density nickel-hydrogen battery.

[0091] Comparative Example 2

[0092] This comparative example prepares a high energy density nickel-hydrogen battery (called Mg 55 Pd4Ni 41 / Ni(OH)2 full battery), the preparation method of this comparative example is different from that of Example 3 only in that the electrolyte used is different. This comparative example uses a KOH solution with a molar concentration of 6M (the traditional electrolyte of nickel-hydrogen batteries), and the other steps are the same as those of Example 3.

[0093] The battery prepared in Example 3 and the battery prepared in Comparative Example 2 were tested respectively. The test results are shown in FIG. Figure 7-9 shown.

[0094] Figure 7 Mg 55 Pd4Ni 41 Charging curves, standing process and the relationship between standing time and discharge capacity of Ni(OH)2 full battery in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte (the amount of active material is expressed as Mg 55 Pd4Ni 41 The mass of the alloy is calculated). It can be seen that in 6M KOH electrolyte, with the increase of standing time, Mg 55 Pd4Ni 41 / Ni(OH)2 full battery's remaining capacity decreases rapidly, and after standing for 60h under full charge, its remaining capacity is only 391.2mAh / g. 55 Pd4Ni 41The self-discharge of the Ni(OH)2 full battery in 4.5M tetramethylammonium hydroxide electrolyte is much lower than that in 6M KOH electrolyte, and the residual capacity is still 467.9mAh / g after standing for 60h in a fully charged state. This shows that the electrolyte has an impact on the self-discharge performance of the nickel-hydrogen battery. The present invention uses tetramethylammonium hydroxide as the electrolyte to reduce the self-discharge of the nickel-hydrogen battery, increase the discharge capacity of the electrode material, and thus improve the energy density of the nickel-hydrogen battery.

[0095] Figure 8 Mg 55 Pd4Ni 41 Charge and discharge curves of the full Ni(OH)2 cell in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte (the amount of active material is calculated based on Mg 55 Pd4Ni 41 Calculated by the sum of the mass of the alloy and Ni(OH)2). Mg 55 Pd4Ni 41 The full battery of Ni(OH)2 has a discharge specific energy of 212.2Wh / kg in 4.5M tetramethylammonium hydroxide electrolyte, while in 6M KOH electrolyte, Mg 55 Pd4Ni 41 / Ni(OH)2 full battery has a discharge specific energy of only 187.2Wh / kg.

[0096] Fig. 9 Mg 55 Pd4Ni 41 Cyclic discharge specific energy diagram of / Ni(OH)2 full battery in 6M KOH electrolyte and 4.5M tetramethylammonium hydroxide electrolyte. Fig. 9 It can be seen that after 15 cycles, Mg 55 Pd4Ni 41 / Ni(OH)2 full battery has only 109.5Wh / kg of discharge specific energy left in 6M KOH electrolyte, while Mg 55 Pd4Ni 41 The / Ni(OH)2 full cell also has a discharge specific energy of 187.2Wh / kg in 4.5M tetramethylammonium hydroxide electrolyte.

[0097] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A high energy density nickel-hydrogen battery, characterized in that: The electrolyte of the nickel-hydrogen battery is tetramethylammonium hydroxide aqueous electrolyte, and the negative electrode material is Mg 55 Pd4Ni 41 , the positive electrode material is Ni(OH)2.

2. A high energy density nickel-hydrogen battery according to claim 1, characterized in that: The electrolyte is a tetramethylammonium hydroxide solution with a molar concentration of 4.5 mol / L.

3. A high energy density nickel-hydrogen battery according to claim 1, characterized in that: The preparation method of the tetramethylammonium hydroxide solution comprises the following steps: (1) calculating the required mass of tetramethylammonium hydroxide according to the molar concentration of the tetramethylammonium hydroxide solution to be prepared, and weighing the corresponding mass of tetramethylammonium hydroxide; (2) adding water to dissolve the weighed tetramethylammonium hydroxide to obtain solution A; (3) draining solution A obtained in step (2) into a volumetric flask; (4) Pour distilled water into the volumetric flask to the mark, cover the bottle with a stopper, and shake well to obtain the tetramethylammonium hydroxide solution.

4. A high energy density nickel-hydrogen battery according to claim 1, characterized in that: The Mg 55 Pd4Ni 41 The method for preparing the negative electrode material comprises the following steps: (1) Press Mg 55 Pd4Ni 41 Weigh Mg, Pd and Ni powder materials in a stoichiometric ratio and mix them evenly to obtain mixed powder A; (2) placing the mixed powder in a ball mill, introducing argon gas into the ball mill and performing ball milling; (3) After the ball milling is completed, the Mg 55 Pd4Ni 41 Negative electrode material alloy powder; (4) The Mg obtained in step (3) 55 Pd4Ni 41 The negative electrode material alloy powder and the Ni powder are uniformly mixed in a mass ratio of 1:4 to obtain a mixed powder B; (5) Place the mixed powder B in a mold and cold press it into a sheet to obtain a sheet of Mg 55 Pd4Ni 41 Negative electrode material.

5. A high energy density nickel-hydrogen battery according to claim 4, characterized in that: During the ball milling, the ball-to-material ratio of the grinding balls to the mixed powder is 60:1, and the diameter of the grinding balls is 10 mm.

6. A high energy density nickel-hydrogen battery according to claim 4, characterized in that: The ball milling speed is 450 rpm; the total ball milling time is 60 h, wherein each ball milling time is 30 min and rest time is 15 min, and the rotation direction of the ball milling is opposite after each rest time.

7. A high energy density nickel-hydrogen battery according to claim 4, characterized in that: The diameter of the mold is 10 mm, and the mixed powder B is cold pressed into a round piece with a diameter of 10 mm.

8. A high energy density nickel-hydrogen battery according to claim 4, characterized in that: The cold pressing pressure is 15 to 30 MPa.

9. The method for preparing a high energy density nickel-hydrogen battery according to claim 1, characterized in that: The following steps are involved: (1) Pressing the positive electrode material and the negative electrode material into sheets respectively; (2) placing the positive electrode material and the negative electrode material into the electrolytic cell in sequence; (3) injecting tetramethylammonium hydroxide aqueous electrolyte into the electrolytic cell and sealing it to obtain the high energy density nickel-hydrogen battery.

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