CN104862514A - Surface modifying method of AB3 type hydrogen storage alloy - Google Patents

Abstract

The invention discloses a surface modifying method of AB3 type hydrogen storage alloy. AB3 type Mm0.78Mg0.22Ni2.48Mn0.09Al0.23Co0.47 parent alloy is prepared through a vacuum induction melting method, and after an alloy ingot is mechanically smashed, particle powder of 200-300 meshes is screened out through ball milling; 95-99% of Mm0.78Mg0.22Ni2.48Mn0.09Al0.23Co0.47 and 1-5% of grapheme are mixed evenly, then ball milling is carried out, and accordingly the AB3 type hydrogen storage alloy with the surface modified is prepared. The method is easy to operate and popularize on a large scale, and the modified AB3 type hydrogen storage alloy can be used for manufacturing hydrogen storage alloy electrodes with good electrochemistry performance.

Description

A kind of AB 3the surface modifying method of type hydrogen storage alloy

Technical field

The invention belongs to materials chemistry and electrochemical research field, particularly Graphene is to AB ₃type Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47(Mm is mishmetal, and the weight percent of composition is: 82.3% La and 17.7% Nd) hydrogen storage alloy carries out the method for surface modification.

Background technology

Current business-like Ni/MH cell negative electrode material mainly uses AB ₅type hydrogen storage alloy, but its specific storage is close to theoretical value, be difficult to improve its capacity again, and electric bicycle, electromobile and hybrid electric vehicle on market etc. need high specific storage, high-power, are therefore badly in need of exploitation new heavy body, more powerful Ni/MH cell negative electrode material.AB ₃type hydrogen storage alloy has relatively high loading capacity, and thus application prospect is good, but its surface is oxidizable, perishable, cyclical stability is poor, makes it be restricted in practical application.Relevant Graphene is to AB at present ₃the research of type alloy surface modifying is less.

Summary of the invention

The object of this invention is to provide a kind of AB ₃the surface modifying method of type hydrogen storage alloy.

Thinking of the present invention: using conductive graphene as properties-correcting agent, with AB ₃type alloy prepares Mm by ball milling _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47/ Graphene modified alloy, forms the protective membrane of one deck densification at alloy surface, slow down the corrosion oxidation of alkali lye alloy, simultaneously by the fixed action of Graphene alloy powder, suppresses the efflorescence speed of alloy, reaches and improve AB ₃the object of type alloy electrode chemical property.

Concrete steps are:

(1) AB is prepared by vacuum induction melting method ₃type Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47precursor alloy, after alloy pig mechanical disintegration, with rotating speed 250 ~ 300 revs/min of ball millings 60 ~ 90 minutes, sieves out 200 ~ 300 object Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder; Described Mm is mishmetal, and the weight percent of its composition is: 82.3% La and 17.7% Nd.

(2) by Mm obtained for step (1) _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder and Graphene mix according to following weight percent: Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder is 95 ~ 99%, and Graphene is 1 ~ 5%, and sum of the two is 100%; Carry out ball milling after mixing, drum's speed of rotation is 200 ~ 250 revs/min, and Ball-milling Time is 30 ~ 60 minutes, i.e. the AB of obtained surface modification ₃type hydrogen storage alloy.

The inventive method is simple to operate, is easy to large-scale promotion, and modified AB ₃type hydrogen storage alloy can prepare the hydrogen-bearing alloy electrode having good electrical chemical property.

Embodiment

embodiment 1:

(1) AB is prepared by vacuum induction melting method ₃type Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47precursor alloy, after alloy pig mechanical disintegration, with rotating speed 300 revs/min of ball millings 60 minutes, sieves out 300 object Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder; Described Mm is mishmetal, and the weight percent of its composition is: 82.3% La and 17.7% Nd.

(2) by Mm obtained for step (1) _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder and Graphene mix according to following weight percent: Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder is 99%, and Graphene is 1%, and sum of the two is 100%; Carry out ball milling after mixing, drum's speed of rotation is 200 revs/min, and Ball-milling Time is 30 minutes, i.e. the AB of obtained surface modification ₃type hydrogen storage alloy.

embodiment 2:

In step (2), raw material weight per-cent changes into: Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder be 98% and Graphene be 2%, all the other are with embodiment 1.

embodiment 3:

In step (2), raw material weight per-cent changes into: Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder be 95% and Graphene be 5%, all the other are with embodiment 1.

Measure with LAND 5.3B battery test system and CHI 660E electrochemical workstation cyclical stability and the dynamic performance that the present embodiment obtains modified alloy respectively, result is as follows:

1) alloy electrode is at interpolation Graphene after milled processed, along with the increase of Graphene consumption, maximum discharge capacity is first increased to 364.9 mAh/g (Graphene consumption is 2%) from 292.0 m Ah/g (not graphene-containing), then drops to again 364.9 mAh/g (Graphene consumption is 5%).

2), after adding Graphene, exchange current density, the limit current density of electrode all present the trend first increasing and reduce afterwards.In studied electrode, when Graphene consumption is 2%, electrode has best comprehensive electrochemical.

Above-mentioned result of study confirms, ball milling does not change the structure of precursor alloy, and modified alloy is by LaNi ₅phase and La ₂ni ₇phase composite, and Graphene is as surface-modifying agent, can not only improve AB ₃type Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47the loading capacity of alloy electrode, can also improve the kinetic property of electrode.

Claims (1)

1. an AB ₃the surface modifying method of type hydrogen storage alloy, is characterized in that concrete steps are:

(1) AB is prepared by vacuum induction melting method ₃type Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47precursor alloy, after alloy pig mechanical disintegration, with rotating speed 250 ~ 300 revs/min of ball millings 60 ~ 90 minutes, sieves out 200 ~ 300 object Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder; Described Mm is mishmetal, and the weight percent of its composition is: 82.3% La and 17.7% Nd;

(2) by Mm obtained for step (1) _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder and Graphene mix according to following weight percent: Mm _0.78mg _0.22ni _2.48mn _0.09al _0.23co _0.47alloying pellet powder is 95 ~ 99%, and Graphene is 1 ~ 5%, and sum of the two is 100%; Carry out ball milling after mixing, drum's speed of rotation is 200 ~ 250 revs/min, and Ball-milling Time is 30 ~ 60 minutes, i.e. the AB of obtained surface modification ₃type hydrogen storage alloy.