CN101936913A - Method for measuring conversion rate of trivalent nickel in cathode material of nickel-metal hydride accumulator - Google Patents

Abstract

The invention discloses a method for measuring the conversion rate of trivalent nickel in the cathode material of a nickel-metal hydride accumulator anode material. The method comprises the following steps of: (a) cleanly washing an active material of a formed positive polaranode plate, drying to a constant weight, sampling, crushing and sieving; (b) weighting a prepared sample at a room temperature, adding a dilute sulphuric acid solution, adding solid potassium iodide, dissolving, diluting, immediately titrating with a standard sodium hyposulfite solution C1 to a titrating destination of V1 and calculating the percentage content of the trivalent nickel according to C1, V1 and a weighed sampleting amount; (c) titrating with a standard EDTA (Ethylene Diamine Tetraacetic Acid) solution C2 to a titrating destination of V2 and calculating the contentpercentage of the bivalent nickel according to C2, V2 and a weighed sampleting amount; and (d) acquiring the conversion rate of the trivalent nickel according to a ratio of the trivalent nickel to the bivalent nickel. The method is convenient and rapid, has the characteristics of high accuracy, less medicine consumption and little environmental pollution and is suitable for rapidly analyzing the production process of the accumulator.

Description

A kind of method of measuring 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode

Technical field

The invention belongs to the accumulator field, be specifically related to a kind of method of measuring 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode.

Background technology

At present, nickel-metal hydrides (Ni-MH) battery be a kind of with hydrogen bearing alloy as negative material, with Ni (OH) ₂Novel secondary cell for main positive electrode, it is a kind of accumulator safer in the current green energy resource, light, long service life, be that replacement is the best green power of automobile of raw material power with gasoline, except that such use, the metal hydride nickel-based battery also is widely used in electric bicycle, electric tool or the like.

Ni-MH has Co-Ni, Cd-Ni, and accumulators such as Zn-Ni, its positive electrode active materials all is a nickel hydroxide, forms NiOOH during charging, becomes Ni (OH) during discharge again ₂, therefore measure the content of 3 valency nickel in the nickel hydroxide and can analyze the degree that the battery charging and discharging reaction is carried out, the mechanism of research electrode reaction.

Relevant 3 valency nickel Determination on content method bibliographical informations seldom, some document is only mentioned and is used iodimetric titration, but does not all provide concrete analytical approach, the research of the present invention by this respect aims to provide a specific analytical method of measuring 3 valency nickel.Nickel-metal hydrides (Ni-MH) accumulator green production. art prescription is different, and its chemical composition also is not quite similar, and electrochemical properties is also different.In nickel-metal hydrides (Ni-MH) accumulator positive electrode material, mainly with Ni (OH) ₂Be main, account for about 75%, add some active substances in addition, have nickel foam to account for 13%, the Ni powder accounts for 3.0%, and Co accounts for 2.0%, and the organic active agent accounts for 3.0%, and Co can improve Ni (OH) ₂Utilization factor, increase Ni in the electrochemical process ²⁺/ Ni ³⁺Between reversibility, improve mass transfer and electric conductivity, improve oxygen evolution potential, reduce inner pressure of battery.

Discharge and recharge reaction equation as can be known from battery electrode:

Understand the conversion ratio of NiOOH, promptly nickel-hydrogen accumulator in process of production, the effect that charging changes into, Ni ³⁺/ Ni (OH) ₂Percent be very important.

Summary of the invention

The object of the present invention is to provide a kind of method of measuring 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode.

Principle: the sample that adds the positive active material after a certain amount of the changing into then to wherein adding the solid potassium iodide, utilizes the oxidisability of 3 valency nickel ions that iodide ion is oxidized to simple substance I in dilution heat of sulfuric acid ₂, make indicator with starch, use standard N a ₂S ₂O ₃Solution titration I ₂Simple substance, solution are become colorless by blueness and are titration end-point, then, continue at Na ₂S ₂O ₃In the solution after the titration, with ammonia buffer solution, regulator solution is used the EDTA standard solution titration again to PH=10, and to become pure blue be titration end-point to solution by spilling redness, the Na that consumes according to titration ₂S ₂O ₃With the volume of EDTA, calculate the conversion ratio of 3 valency nickel.Chemical equation is as follows:

2NiOOH+6H ⁺+2I ^-＝I ₂+4H ₂O+2Ni ⁺⁺

I ₂+2S ₂O ₃ ^2-＝S ₄O ₆ ^2-+2I ^-

Ni ⁺⁺+H ₂Y ^＝＝2H ⁺+NiY ^＝

Co ⁺⁺+H ₂Y ^＝＝2H ⁺+CoY ^＝

Purpose of the present invention can be achieved through the following technical solutions:

A kind of method of measuring 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode comprises the steps:

A, sample preparation

After the pole plate active material of the positive pole after Ni-metal hydride accumulator changed into was rinsed well, wet pole plate need be dried to constant weight, and the pole plate active material is taken a sample, pulverizes, sieved;

The quality percentage composition of b, detection 3 valency nickel

At normal temperatures, take by weighing the prepared sample of step a, add in the iodine flask, add dilution heat of sulfuric acid, and then add the solid potassium iodide, seal with deionized water, slowly rock iodine flask equably, be placed on the dark place, make to fully the dissolving after, purge bottleneck and inwall make test solution after adding deionized water dilution, and test solution is divided into n part, getting wherein, m part changes over to respectively in m the conical flask, n 〉=3,3≤m≤n wherein, getting a copy of it solution is C with concentration immediately ₁Sodium thiosulfate standard solution, titration is to light yellow, add appropriate amount of starch continue to drip form sediment to blueness just decorporated for titration end-point be V ₁, according to C ₁, V ₁Reach the quality percentage composition that sample weighting amount calculates 3 valency nickel, METHOD FOR CONTINUOUS DETERMINATION m time, results averaged, computing formula is as follows:

${\mathrm{Ni}}^{3+}\%=\frac{C_1\×V_1\×58.69\×n/1000}{G}\×100\%$

In the formula: C ₁Be standard solution Na ₂S ₂O ₃Concentration mol/L

V ₁The standard solution Na that is consumed during for titration end-point ₂S ₂O ₃Volume ml

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel;

The quality percentage composition of c, detection divalent nickel

With the solution after the usefulness sodium thiosulfate titration among the step b, ammonification buffer solution, regulator solution add an amount of solid murexide indicator to PH=10, are C with concentration ₂The EDTA standard solution titration, becoming aubergine by yellow is that titration end-point is V ₂, according to C ₂, V ₂And the quality percentage composition of sample weighting amount calculating divalent nickel, METHOD FOR CONTINUOUS DETERMINATION m time, results averaged, computing formula is as follows:

${\mathrm{Ni}}^{2+}\%=\frac{C_2\×V_2\×58.69\×n/1000}{G}\×100\%-2\%$

In the formula: C ₂Concentration mol/L for standard solution EDTA

V ₂The volume ml of the standard solution EDTA that is consumed during for titration end-point

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel

2%-is for adding the amount of cobalt, with EDTA standard solution titration Ni in the prescription ²⁺The time, Co ²⁺Also simultaneously titrated, and the molecular weight of Ni, Co differs very little, the molecular weight of Co is 58.93, the molecular weight of Ni is 58.69;

The conversion ratio of d, calculating 3 valency nickel

Obtain the conversion ratio of 3 valency nickel by the ratio of 3 valency nickel quality percentage compositions and divalent nickel quality percentage composition

Conversion ratio: Ni ³⁺%/Ni ²⁺% * 100%.

The method of 3 valency nickel conversion ratios in the said determination Ni-metal hydride accumulator positive electrode, the pole plate active material of the positive pole after the metal accumulator changes among the step a need wash with tap water, after removing electrolytic solution, rinse well with deionized water, wet pole plate bake out temperature is 105～110 ℃ again, sample will be dried to constant weight, the pole plate active material is pressed diagonal line sampling, can make sample have sufficient representativeness, with materials and be broken to 100 orders, all sieve, guarantee fineness.

The method of 3 valency nickel conversion ratios in the said determination Ni-metal hydride accumulator positive electrode, sample size that takes by weighing among the step b and the w/v between the dilute sulfuric acid (g: be 0.5～1.5: 1 L), be that every 0.5g～1.5g sample need add the dissolving of 1L dilute sulfuric acid, the PH of the dilution heat of sulfuric acid that adds is 1.20-1.28, the PH of preferred dilution heat of sulfuric acid is 1.25, and the normal temperature temperature is preferably 20 ℃～25 ℃.

The method of 3 valency nickel conversion ratios in the said determination Ni-metal hydride accumulator positive electrode, the sodium thiosulfate standard solution concentration described in the step b is preferably 0.1mol/L.

The method of 3 valency nickel conversion ratios in the said determination Ni-metal hydride accumulator positive electrode, the EDTA standard solution described in the step c are that concentration is preferably 0.1mol/L.

Beneficial effect of the present invention:

Method of the present invention is based on chemical reaction, by the variation of chemical element valence state, measures a kind of chemical analysis method of the amount of substance of element valence variation.Can be fast, accurately, measure Ni in the MH-Ni accumulator positive electrode material ²⁺And Ni ³⁺Percentage composition and Ni ³⁺Conversion ratio, judge the effect that battery charge changes into.Adopt this method, use medicine few, easy, fast, reliable results.Utilize the variation of chemical element valence state, determine its composition content, and instrument analytical method can not be determined directly, compares with instrumental method, and the superiority of its method is arranged, and can satisfy the express-analysis requirement of accumulator production demand.

Embodiment

The preparation of embodiment 1 reagent

1.1,0.1mol/L Na ₂S ₂O ₃The preparation of standard solution and demarcation:

Preparation; Take by weighing 26g sodium thiosulfate (Na ₂S ₂O ₃.5H ₂O), be dissolved in the 1000ml water, slowly boil 10min, the back filtration of 2 weeks is placed in cooling, and is to be calibrated.

Demarcate; Take by weighing 0.15g in 120 ℃ of base weight potassium chromates of drying, claim accurate to 0.0001g to constant weight.Place iodine flask, be dissolved in 25ml water, add rare H of 2g potassium iodide and 20ml 20% ₂SO ₄, shake up, place 10min in the dark place and add 150ml water, with the sodium thiosulfate solution titrated for preparing, add 3ml starch indicator solution (10g/l) during nearly terminal point, continue titration to solution and become bright green by blueness.Do blank test simultaneously.

The concentration of sodium thiosulfate standard solution is calculated as follows;

$C\left({\mathrm{Na}}_2{S}_2{O}_3\right)=\frac{m}{(V_1-V_2)*0.04903}$

In the formula: C (Na ₂S ₂O ₃The amount of substance concentration mol/L of)-sodium thiosulfate standard solution

The quality g of m-potassium dichromate

V ₁The usefulness of-sodium thiosulfate standard solution is measured ml

V ₂The usefulness of-blank test sodium thiosulfate standard solution is measured ml

0.04903-the quality of suitable with the accurate solution of the 1.00ml sodium thiosulfate standard configuration system potassium dichromate with the gram expression

1.2, the preparation and the demarcation of 0.1mol/L EDTA standard solution:

Preparation: take by weighing the 40g disodium ethylene diamine tetraacetate, heating for dissolving is in 1000ml water, and cooling shakes up.

Demarcate: take by weighing the benchmark zinc paste of 0.25g, claim accurate to 0.0001g in 800 ℃ of calcinations to constant weight.Wetting with low amounts of water, add 2ml 20% hydrochloric acid solution, make sample dissolution, add 100ml water, be neutralized to PH7-8 with 10% ammonia spirit, the eriochrome black T indicator solution that adds 10ml ammonia-sal-ammoniac buffer solution (PH=10) and 5 5g/l becomes pure blue with disodium ethylene diamine tetra-acetic acid solution titration to the solution for preparing by purple, does blank test simultaneously.

$C\left(\mathrm{EDTA}\right)=\frac{m}{(V_1-V_2)*0.08138}$

In the formula: the amount of substance concentration mol/L of C (EDTA)-disodium ethylene diamine tetra-acetic acid solution

The quality g of m-zinc paste

V ₁The usefulness of-disodium ethylene diamine tetra-acetic acid solution is measured ml

V ₂The usefulness of-blank examination disodium ethylene diamine tetra-acetic acid solution is measured ml

0.08138-the quality of suitable with the 1.00ml disodium ethylene diamine tetra-acetic acid solution zinc paste with the gram expression

1.3, the preparation (PH=10) of ammonia buffer solution:

Take by weighing 54.0g ammonium chloride, water-soluble, add 350ml ammoniacal liquor, be diluted to 1000ml.

1.4, the preparation (10g/l) of starch indicator solution:

Take by weighing Fen, 1.0g shallow lake, add 5ml water and make into pasty state, under agitation pastel is added in the water of 90ml boiling, boil 1-2min, cooling is diluted to 100ml.

Embodiment 2 measures 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode

A, sample preparation

The pole plate active material of the positive pole after the MH-Ni accumulator changes into need wash with tap water, behind the removal electrolytic solution, rinses well with deionized water again.Wet pole plate needs oven dry, and baking temperature is 105～110 ℃, and be 1.5 hours drying time, and sample will be dried to constant weight, the pole plate active material is pressed the diagonal line sampling, and sample will have sufficient representativeness, and sample size is about 200 grams, be broken to 100 orders, all sieve, guarantee fineness.

The quality percentage composition of b, detection 3 valency nickel

Under the normal temperature, take by weighing the sample 0.4000g of step a preparation, claim accurate to 0.0001g, add in the 500ml iodine flask, add the dilution heat of sulfuric acid 300ml of PH=1.25, and then add 6.0g solid potassium iodide, seal with deionized water, slowly rock iodine flask equably, be placed on the dark place, make to fully the dissolving after, purge bottleneck and inwall, add deionized water and be settled in the 500ml volumetric flask, solution is divided into 4 parts, draw the 125ml test solution respectively with transfer pipet, put into 3 250ml conical flasks respectively, use the 0.1mol/L sodium thiosulfate standard solution immediately, titration is to light yellow, add 5ml starch continue to drip form sediment to blueness just decorporated for titration end-point be V ₁, calculate the quality percentage composition of 3 valency nickel, survey results averaged continuously 3 times.Computing formula is as follows:

${\mathrm{Ni}}^{3+}\%=\frac{C_1\×V_1\×58.69\×4/1000}{G}\×100\%$

In the formula: C ₁Be standard solution Na ₂S ₂O ₃Concentration mol/L

V ₁The standard solution Na that is consumed during for titration end-point ₂S ₂O ₃Volume ml

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel

The quality percentage composition of c, detection divalent nickel

PH value with the ammonia buffer solution 10ml regulator solution of PH=10 adds an amount of solid murexide indicator, and with 0.1mol/L EDTA standard solution titration, becoming aubergine by yellow is that titration end-point is V ₂, the quality percentage composition of calculating divalent nickel.Survey 3 times results averaged continuously.Computing formula is as follows:

${\mathrm{Ni}}^{2+}\%=\frac{C_2\×V_2\×58.69\×4/1000}{G}\×100\%-2\%$

In the formula: C ₂Concentration mol/L for standard solution EDTA

V ₂The volume ml of the standard solution EDTA that is consumed during for titration end-point

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel

The conversion ratio of d, calculating 3 valency nickel

Obtain the conversion ratio of 3 valency nickel: Ni by the ratio of 3 valency nickel and divalent nickel ³⁺%/Ni ²⁺% * 100%.

Above-mentioned titration determination result such as table 1:

The titration testing result of table 1 embodiment 2

Number of times/the project of detection	V 1(ml)	V 2(ml)	Ni 3+％	Ni 2+％
					For the first time	7.60	8.10	44.60	47.50
For the second time	7.59	8.09	44.55	47.48
					For the third time	7.61	8.09	44.65	47.48
Ni 3+％、Ni 2+% mean value	-	-	44.60	47.49

According to gained data computation Ni in the table ³⁺Conversion ratio is: 44.60%/47.49% * 100%=93.91%

The influence of embodiment 3 acidity

Airborne oxygen is easily with the I in the solution ^-Be oxidized to I ₂, make the result of mensuration higher, for avoiding the interference of oxygen in the air, take by weighing the anodal sample after a certain amount of the changing into, be dissolved in the 100ml dilute sulfuric acid of different acidity, each adds 2 gram solid potassium iodides, after treating dissolving fully, add the starch indicator of 2ml (10g/L), be placed in the air, begin to clock, observe its change in color, and the easy more oxidation by air of short more expression of time of record change color, see Table 2 as reference, seek suitable analysis condition.

During anodal sample dissolution after changing into, will make airborne oxygen participate in reaction, make test result higher if acidity is too high, if acidity is too small, can make dissolution velocity too slow, waste time and energy, below by do the test of acidity in 0.90-1.35PH value scope the sample dissolution influence.

Table 2PH value is to the influence of the oxidization time of solution

PH	1.35	1.28	1.25	1.20	1.10	1.00	0.9
								Sample mass mg	90.11	90.05	90.04	90.07	90.52	90.63	90.71

Oxidization time min

90

80

45

30

26

10

6

As can be known from the above table, the proper acidity scope is between 1.20-1.28, and the acidity optimal period condition optimization of this method is the dilution heat of sulfuric acid of PH=1.25, dissolved samples.

The influence of embodiment 4 sample masses

By the test of blank as can be known, under the same situation of other conditions, dissolve in the blank assay change into after the quality of anodal sample many more, being placed in the air time of solution turned blue is that oxidization time is just short more, so,, can make the time lengthening of dissolving if the sample dissolution quality is many more, oxygen participates in oxidation reaction in the air, cause the result higher, if the quality of dissolving is few more, though sample is dissolved fully, but the solution concentration after the dissolving is too little, can cause error at measurment.Take by weighing different samples respectively, add the 100ml pH value in each sample and be 1.25 dilute sulfuric acid dissolving, each adds 2 gram solid potassium iodides, treat dissolving fully after, add the starch indicator of 2ml (10g/L), be placed in the air, pick up counting, observe its change color, and record data, see Table 3

Anodal sample mass after table 3 changes into is to the influence of solution oxide time

?PH	1.25	1.25	1.25	1.25	1.25
						Anodal sample mass mg	71.9	88.5	148.8	209.7	302.5
Solution turned blue time min	84	78	65	38	26

By test, take all factors into consideration the w/v (g: L) 0.5～1.5: 1 of sample size and adding dilute sulfuric acid.

The test of embodiment 5 precision relative standard deviations:

1, the operation steps of precision test is identical with embodiment 2.

2, get 6 duplicate samples, measure the quality percentage composition of its 3 valency nickel respectively, each sample replication 8 times writes down each measurement result, and calculates its SD (standard deviation) and RSD (relative standard deviation), sees Table 4

The testing result of nickelic quality percentage composition among table 4 embodiment 5

Standard deviation＜16.58*10 ^-2, relative standard deviation between 0～5% the time experiment effect better, the relative standard deviation of present embodiment is all less than 0.5%, the precision of this illustration method is better.

Embodiment 6:Ni ³⁺The checking of conversion ratio:

With batch 16Ah Ni-MH battery of assembling, change into standard by three kinds of differences respectively and change into, and measure discharge capacity of the cell, press same standard full charge after capacity check finishes again, dissect and measure nickelic content (Ni substrate defoams) in the positive plate, result such as table 6:

Table 5 embodiment 6 detects data

Change into standard	Discharge current (A)	Discharge capacity (Ah)	Ni 3+％	Ni 2+％	Ni 3+Conversion ratio
						Standard 1	?16	16.47	40.87％	48.21％	84.78％
Standard 2	?16	16.95	43.49％	48.20％	90.22％
						Standard 3	?16	17.33	46.64％	48.21％	96.74％

As can be known from the above table: under the constant situation of discharge current (A), Ni ³⁺The high more or Ni of quality percentage composition ³⁺Conversion ratio high more, discharge capacity (Ah) is also big more.

At the spherical inferior nickel (Ni (OH) of positive active material ₂) amount one regularly, mainly by optimizing the standard that changes into of battery, improve the transformation efficiency that spherical inferior nickel (nickelous) in the charging process changes into hydroxy nickel oxide (nickelic), can improve the energy density (capacity of battery under the unit mass) of battery.Be converted into hydroxy nickel oxide (nickelic) after spherical inferior nickel (nickelous) charging, by measuring the content of the hydroxy nickel oxide in the charging back positive plate fully, or its conversion ratio is the formation effect of decidable battery, also can extrapolate the capacity height of battery simultaneously.

Claims (9)

1. a method of measuring 3 valency nickel conversion ratios in the Ni-metal hydride accumulator positive electrode is characterized in that comprising the steps:

A, sample preparation

After the pole plate active material of the positive pole after Ni-metal hydride accumulator changed into was rinsed well, wet pole plate need be dried to constant weight, and the pole plate active material is taken a sample, pulverizes, sieved;

The quality percentage composition of b, detection 3 valency nickel

At normal temperatures, take by weighing the prepared sample of step a, add in the iodine flask, add dilution heat of sulfuric acid, and then add the solid potassium iodide, seal with deionized water, slowly rock iodine flask equably, be placed on the dark place, make to fully the dissolving after, purge bottleneck and inwall make test solution after adding deionized water dilution, and test solution is divided into n part, getting wherein, m part changes over to respectively in m the conical flask, wherein n 〉=3,3≤m≤n is C with concentration immediately ₁The sodium thiosulfate standard solution titration to light yellow, add appropriate amount of starch continue to drip form sediment to blueness just decorporated for titration end-point be V ₁, according to C ₁, V ₁Reach the quality percentage composition that sample weighting amount calculates 3 valency nickel, METHOD FOR CONTINUOUS DETERMINATION m time, results averaged, computing formula is as follows:

${\mathrm{Ni}}^{3+}\%=\frac{C_1\×V_1\×58.69\×n/1000}{G}\×100\%$

In the formula: C ₁Be standard solution Na ₂S ₂O ₃Concentration mol/L

V ₁The standard solution Na that is consumed during for titration end-point ₂S ₂O ₃Volume ml

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel;

The quality percentage composition of c, detection divalent nickel

With the solution after the usefulness sodium thiosulfate titration among the step b, ammonification buffer solution, regulator solution add an amount of solid murexide indicator to PH=10, are C with concentration ₂The EDTA standard solution titration, becoming aubergine by yellow is that titration end-point is V ₂, according to C ₂, V ₂And the quality percentage composition of sample weighting amount calculating divalent nickel, METHOD FOR CONTINUOUS DETERMINATION m time, results averaged, computing formula is as follows:

${\mathrm{Ni}}^{2+}\%=\frac{C_2\×V_2\×58.69\×n/1000}{G}\×100\%-2\%$

In the formula: C ₂Concentration mol/L for standard solution EDTA

V ₂The volume ml of the standard solution EDTA that is consumed during for titration end-point

G is the quality g of the sample that taken by weighing

58.69-be the molecular weight of nickel

2%-is for adding the amount of cobalt, with EDTA standard solution titration Ni in the prescription ²⁺The time, Co ²⁺Also simultaneously titrated, and the molecular weight of Ni, Co differs very little, the molecular weight of Co is 58.93, the molecular weight of Ni is 58.69;

The conversion ratio of d, calculating 3 valency nickel

Obtain the conversion ratio of 3 valency nickel by the ratio of 3 valency nickel quality percentage compositions and divalent nickel quality percentage composition

Conversion ratio: Ni ³⁺%/Ni ²⁺% * 100%.

2. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1, it is characterized in that among the step a, the pole plate active material of the positive pole after the metal accumulator changes into need wash with tap water, behind the removal electrolytic solution, rinses well with deionized water again.

3. the method for 3 valency nickel conversion ratios is characterized in that among the step a in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1, and wet pole plate bake out temperature is 105～110 ℃, and sample will be dried to constant weight.

4. the method for 3 valency nickel conversion ratios is characterized in that among the step a pole plate active material being taken a sample by diagonal line in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1, with materials and be broken to 100 orders, all sieve, guarantee fineness.

5. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1, it is characterized in that the mass volume ratio between the dilute sulfuric acid of sample size and adding among the step b is 0.5～1.5: 1, the PH of the dilution heat of sulfuric acid of adding is 1.20-1.28.

6. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 5 is characterized in that the PH of the dilution heat of sulfuric acid that adds among the step b is 1.25.

7. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1 is characterized in that the sodium thiosulfate standard solution concentration described in the step b is 0.1mol/L.

8. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1 is characterized in that the EDTA standard solution described in the step c is that concentration is 0.1mol/L.

9. the method for 3 valency nickel conversion ratios in the mensuration Ni-metal hydride accumulator positive electrode according to claim 1 is characterized in that the described normal temperature temperature of step b is 20 ℃～25 ℃.