Method for improving electrochemical and dynamic properties of La-Mg-Ni-based alloy electrode

[0021] Example 1

[0022] A method for improving the electrochemical kinetic performance of La-Mg-Ni-based alloy electrodes, the preparation steps are as follows:

[0023] 1. La-Mg-Ni based alloy preparation

[0024] Under the protection of argon, configure the samples according to the molar ratio of La:Mg:Ni:Co=7:3:29.75:5.25. All raw materials are bulk samples, and the Mg is a master alloy MgNi 2 Instead, in order to reduce the Mg element loss due to volatilization during the smelting process, add more MgNi with a mass fraction of 20% 2 , Minus MgNi 2 After the Ni in the alloy, elemental Ni is added to ensure that the proportioning requirements are met, and then the material is smelted by the magnetic suspension induction melting method. In order to ensure uniform smelting, the alloy ingot is repeatedly turned and smelted three times. After crushing part of the alloy through a 250-mesh sieve, it is divided into three equal parts.

[0025] 2. Preparation of La-Mg-Ni-based alloy electrode material

[0026] Put one part of the alloy powder obtained from the above 250 mesh sieve into a ball milling tank, and then use a planetary ball mill to directly ball mill for 10 minutes under the protection of argon. The ball-to-battery ratio during ball milling is 20:1 and the speed is 250 rpm. Then, the prepared sample and the carbonyl nickel powder are configured with a mass ratio of 1:4, and after uniform mixing, they are pressed under a pressure of 20 MPa to form a circular electrode sheet with a diameter of 10 mm and a thickness of 1 mm. Finally, the prepared electrode sheet was used as the negative electrode, the 6mol/L KOH aqueous solution was used as the electrolyte, and the sintered Ni(OH) 2 The /NiOOH electrode is the positive electrode, and the Hg/HgO is used as the reference electrode to perform various electrochemical performance tests in an open three-electrode system.

[0027] Example 2

[0028] A method for improving the electrochemical kinetic performance of La-Mg-Ni-based alloy electrodes, the preparation steps are as follows:

[0029] 1. La-Mg-Ni-based alloy preparation:

[0030] Under the protection of argon, configure the samples according to the molar ratio of La:Mg:Ni:Co=7:3:29.75:5.25. All raw materials are bulk samples, and the Mg is a master alloy MgNi 2 Instead, in order to reduce the Mg element loss due to volatilization during the smelting process, add more MgNi with a mass fraction of 20% 2 , Minus MgNi 2 After the Ni in the alloy, elemental Ni is added to ensure that the proportioning requirements are met, and then the material is smelted by the magnetic suspension induction melting method. In order to ensure uniform smelting, the alloy ingot is repeatedly turned and smelted three times. After crushing part of the alloy through a 250-mesh sieve, it is divided into three equal parts.

[0031] 2. Preparation of La-Mg-Ni/graphene alloy electrode material:

[0032] Put one part of the alloy powder obtained through the 250 mesh sieve into a ball mill tank, and add graphene with a mass fraction of 2% at the same time. Then, under the protection of argon gas, use a planetary ball mill to directly mechanically ball mill for 10 minutes. The ball-to-material ratio during ball milling is 20:1, the rotation speed is 250 rpm, then the prepared sample and the carbonyl nickel powder are configured in a mass ratio of 1:4, and after uniform mixing, they are pressed under a pressure of 20MPa to form a circular electrode sheet with a diameter of 10mm and a thickness of 1mm . Finally, the prepared electrode sheet was used as the negative electrode, the 6mol/L KOH aqueous solution was used as the electrolyte, and the sintered Ni(OH) 2 The /NiOOH electrode is the positive electrode, and the Hg/HgO is used as the reference electrode to perform various electrochemical performance tests in an open three-electrode system.

[0033] Example 3

[0034] A method for improving the electrochemical kinetic performance of La-Mg-Ni-based alloy electrodes, the preparation steps are as follows:

[0035] 1. La-Mg-Ni-based alloy preparation:

[0036] Under the protection of argon, configure the samples according to the molar ratio of La:Mg:Ni:Co=7:3:29.75:5.25. All raw materials are bulk samples, and the Mg is a master alloy MgNi 2 Instead, in order to reduce the Mg element loss due to volatilization during the smelting process, add more MgNi with a mass fraction of 20% 2 , Minus MgNi 2 After the Ni in the alloy, elemental Ni is added to ensure that the proportioning requirements are met, and then the material is smelted by the magnetic suspension induction melting method. In order to ensure uniform smelting, the alloy ingot is repeatedly turned and smelted three times. After crushing part of the alloy through a 250-mesh sieve, it is divided into three equal parts.

[0037] 2. The steps of the La-Mg-Ni/(graphene/composite) alloy electrode material preparation method are as follows:

[0038] First, 100 mg of graphite oxide was dispersed in 50 ml of ethylene glycol solution and ultrasonically oscillated for 1 hour to form a stable graphene colloid. Then add NiSO with a concentration of 1mol/L 4 ·6H 2 25ml of O solution and 25ml of NaOH solution with a concentration of 5mol/L, followed by magnetic stirring for 30min, to obtain a graphene/nickel suspension. Then the suspended matter is separated by a centrifuge, the separated matter is washed with deionized water, and then dried at 60°C. Then the dried mixture was heated from room temperature to 750°C at a heating rate of 5°C/min under a flowing mixed gas (argon/hydrogen=95/5) atmosphere, then kept for 3h and then cooled in the furnace to prepare Graphene/nickel composite. Then put one part of the alloy powder obtained through the 250 mesh sieve into the ball milling tank, and at the same time add the graphene/nickel composite with a mass fraction of 2%, and then use the planetary ball mill to directly mechanically ball mill for 10 minutes under the protection of argon gas. When the ball-to-battery ratio is 20:1, the rotation speed is 250 rpm, and then the prepared sample and the carbonyl nickel powder are configured at a mass ratio of 1:4, and after uniform mixing, they are pressed into a diameter of 10mm and a thickness of 1mm under a pressure of 20MPa. Round electrode sheet. Finally, the prepared electrode sheet was used as the negative electrode, the 6mol/L KOH aqueous solution was used as the electrolyte, and the sintered Ni(OH) 2 The /NiOOH electrode is the positive electrode, and various electrochemical performance tests are carried out in an open three-electrode system.

[0039] Such as Figure 1~3 As shown, the capacity of all alloys can reach the maximum after only 1-2 charge and discharge cycles, showing good activation performance. After adding graphene and graphene/nickel composite, the maximum discharge capacity of the alloy electrode increased from 350mAh/g to 367.7mAh/g and 367.7mAh/g, respectively. After 80 cycles of charge and discharge, the capacity retention rate of the alloy electrode S 80 They are 64.8%, 66.4% and 67.3% respectively. The maximum discharge capacity and cycle stability of the alloy electrode did not decrease, but increased after adding graphene, graphene/nickel composite, and the discharge current density was 1200mA·g -1 When the alloy electrode has high rate discharge performance HRD 1200 From 66.2% before the addition of graphene and graphene/nickel composite to 75.8% and 86.4%, respectively, the kinetic performance is significantly improved. Especially after adding graphene and graphene/nickel composites, the mass transfer resistance is significantly reduced, which greatly improves the charge and discharge efficiency of the La-Mg-Ni-based alloy electrode.