CN103203452A

CN103203452A - Method of surface copper plating modification for AB3 type hydrogen storage alloy

Info

Publication number: CN103203452A
Application number: CN2013101043550A
Authority: CN
Inventors: 黄红霞; 李国辉
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2013-03-28
Filing date: 2013-03-28
Publication date: 2013-07-17

Abstract

The invention discloses a method of surface copper plating modification for AB3 type hydrogen storage alloy. The method includes: under the protection of argon, preparing AB3 type alloy by smelting metal raw materials through vacuum induction, mechanically smashing and ball-milling the alloy, and screening out alloy powder of 200-300 meshes; weighing 0.75g CuSO4 5H2O and dissolving into deionized water, dropwise adding 30-40ml of EDTA (ethylene diamine tetraacetic acid) complexing agent, and stirring for 2min at room temperature as a plating solution; adding 0.4-0.5ml of 18.5 % formalin into 1g of the alloy powder, stirring well prior to slowly dropwise adding the plating solution, magnetically stirring for 30min, filtering, washing the alloy powder with deionized water, vacuum drying for 24h at the temperature of 80 DEG C, and obtaining the AB3 type hydrogen storage alloy with the surface modified by copper plating. By the method, specific capacity, circulating stability and dynamics performance of an electrode are improved, and the electrode can be better applied to Ni/MH secondary batteries.

Description

To AB 3Type hydrogen storage alloy carries out the method for copper coating modification

Technical field

The present invention relates to metallurgical chemistry and electrochemical research field, to AB ₃Type hydrogen storage alloy La _0.35Pr _0.30Mg _0.30Ni _2.90Al _0.30Carry out the copper coating modification, to be applied to power type Ni/MH cell negative electrode material.

Background technology

Hydrogen bearing alloy is as the negative material of Ni/MH secondary cell, good with energy density height, high-rate charge-discharge capability, the overcharging resisting discharge capability strong, have extended cycle life, memory-less effect and environmentally safe, low cost and other advantages, has been subjected to researcher's common concern; Present commercialization AB ₅The discharge capacity of type alloy electrode is 300 ~ 320 mAh/g, near theoretical capacity 348 mAh/g, can not satisfy the requirement of power type Ni/MH battery high-energy-density.Discover new A B ₃The hydrogen storage capability of type La-Mg-Ni alloy is higher than AB ₅The type lanthanon hydrogen storage alloy reaches 360 ~ 410 mAh/g, and environmentally friendly, is considered to the alloy material storing hydrogen of tool potentiality, thereby becomes people's research focus, but AB ₃The type alloying component very easily is subjected to corrosion and the oxidation of strong basicity electrolyte, and simultaneously in continuous charge and discharge process, bigger volumetric expansion takes place alloying component and efflorescence causes the cycle life of alloy sharply to descend.

Summary of the invention

The purpose of this invention is to provide a kind of to AB ₃Type hydrogen storage alloy La _0.35Pr _0.30Mg _0.30Ni _2.90Al _0.30Carry out the method for copper coating modification, with cyclical stability and the kinetic property that improves electrode.

Concrete steps are:

(1) taking by weighing purity according to target product mole proportioning is raw metal more than 99%, prepares AB by vacuum induction melting under argon shield ₃Type alloy La _0.35Pr _0.30Mg _0.35Ni _2.90Al _0.30, after prepared alloy mechanical disintegration, on planetary ball mill, with 225 ~ 250 rev/mins rotating speed ball milling 30 ~ 60 minutes, sieve out 200 ~ 300 purpose alloy powders then and be used for follow-up copper coating and handle.

(2) take by weighing 0.75 gram CuSO ₄5H ₂O is dissolved in deionized water, adds ethylenediamine tetra-acetic acid (EDTA) complexing agent of 30 ~ 40 milliliter of 0.1 mol again, and stirring at room namely made plating bath in 2 minutes.

(3) taking by weighing 1.0 alloy powders that make of gram steps (1), to join 0.4 ~ 0.5 milliliter of mass percent concentration be in 18.5% the formalin, the plating bath that the back dropping step (2) that stirs makes, magnetic agitation 30 ~ 60 minutes, filter, spend the deionised water alloy powder, 80 ℃ of vacuum drying are 24 hours again, namely make the AB of copper coating modification ₃Type hydrogen storage alloy.

The present invention at alloy surface clad metal simple substance, has improved specific capacity, cyclical stability and the dynamic performance of electrode by chemical reduction method, and it better is applied in the Ni/MH secondary cell.The present invention has important significance for theories and real value for the research and development that realizes the high-performance Ni-MH power cell, and will promote the competitiveness of China aspect hydrogen storage material.

The specific embodiment

Embodiment:

(1) taking by weighing purity according to target product mole proportioning is 99.9% raw metal, prepares AB by vacuum induction melting under argon shield ₃Type alloy La _0.35Pr _0.30Mg _0.35Ni _2.90Al _0.30, after prepared alloy mechanical disintegration, on planetary ball mill, with 225 rev/mins rotating speed ball milling 30 minutes, sieve out 300 purpose alloy powders then and be used for follow-up copper coating and handle.

(2) take by weighing 0.75 gram CuSO ₄5H ₂O is dissolved in deionized water, adds ethylenediamine tetra-acetic acid (EDTA) complexing agent of 30 milliliter of 0.1 mol again, and stirring at room namely made plating bath in 2 minutes.

(3) taking by weighing 1.0 alloy powders that make of gram steps (1), to join 0.45 milliliter of mass percent concentration be in 18.5% the formalin, the plating bath that the back dropping step (2) that stirs makes, magnetic agitation 30 minutes, filter, spend the deionised water alloy powder, 80 ℃ of vacuum drying are 24 hours again, namely make the AB of copper coating modification ₃Type hydrogen storage alloy.

With the AB after the copper coating modification ₃Type hydrogen storage alloy makes electrode, measures discharge capacity, cyclical stability and the dynamic performance of electrode, and the result is as follows:

1. after modification was handled, the electrode maximum discharge capacity was increased to 328 mAh/g from 303 mAh/g, and the capability retention after 30 circulations brings up to 67% from 44 %; Alloy surface has increased the copper layer that one deck has the catalysis protective effect after the copper plating treatment; copper plate has improved thermal conductivity, non-oxidizability, resistance to chalking, the corrosion resistance of hydrogen-bearing alloy electrode; prolonged the service life of material; greatly improved the electro catalytic activity of hydrogen bearing alloy; alloy electrode has shown good activity function after the modification, and good cyclical stability.

2. after passing through copper coating, limiting current density is brought up to 1027 mA/g by 619 mA/g, cyclic voltammetry curve anodic oxidation peak current and the peak area of alloy electrode are improved, and illustrate to have surface of good catalytic performance and bigger capacitance after the copper facing modification; This is that the reactivity of alloy electrode, suction/hydrogen desorption kinetics performance are all effectively improved because the coating of alloy surface has delayed oxidation and the corrosion reaction between alloy and the electrolyte to a certain extent, and this can reduce the diffusion rate of H atom in alloy.

Claims

1. one kind to AB ₃Type hydrogen storage alloy carries out the method for copper coating modification, it is characterized in that concrete steps are:

(1) taking by weighing purity according to target product mole proportioning is raw metal more than 99%, prepares AB by vacuum induction melting under argon shield ₃Type alloy La _0.35Pr _0.30Mg _0.35Ni _2.90Al _0.30, after prepared alloy mechanical disintegration, on planetary ball mill, with 225 ~ 250 rev/mins rotating speed ball milling 30 ~ 60 minutes, sieve out 200 ~ 300 purpose alloy powders then and be used for follow-up copper coating and handle;

(2) take by weighing 0.75 gram CuSO ₄5H ₂O is dissolved in deionized water, adds the EDTA complex agent of 30 ~ 40 milliliter of 0.1 mol again, and stirring at room namely made plating bath in 2 minutes;