CN102323228A - The assay method of ferrous iron and ferric iron content in the lithium iron phosphate cathode material - Google Patents

The assay method of ferrous iron and ferric iron content in the lithium iron phosphate cathode material Download PDF

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Publication number
CN102323228A
CN102323228A CN201110168693A CN201110168693A CN102323228A CN 102323228 A CN102323228 A CN 102323228A CN 201110168693 A CN201110168693 A CN 201110168693A CN 201110168693 A CN201110168693 A CN 201110168693A CN 102323228 A CN102323228 A CN 102323228A
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iron
content
protective atmosphere
ferric
cathode material
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尤志宏
董明
李红
兰仙梅
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NANOCHEM SYSTEMS (SUZHOU) CO Ltd
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NANOCHEM SYSTEMS (SUZHOU) CO Ltd
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Abstract

The invention discloses the assay method of ferrous iron and ferric iron content in a kind of lithium iron phosphate cathode material; Promptly under protective atmosphere; Carry out sample preparation and sample determination, comprising: the ferrous iron Determination on content: with lithium iron phosphate cathode material with acid dissolving, regulator solution then PH For 2-9 The time, add that Phen and ferrous iron generate orange complex compound and with the sample determination process of its absorbance of spectrophotometric determination; The mensuration of ferric iron content: lithium iron phosphate cathode material is dissolved with acid, regulator solution PH For 1-3 The time, add sulfosalicylic acid and ferric iron and form violet complex, with its absorbance of spectrophotometric determination; The invention also discloses a kind of protective atmosphere device that designs for the assay method of test ferrous iron and ferric iron content; The protective atmosphere device comprises draft tube, gas outlet, casing, operating space, operation gloves; The operating space charges into inert gas, as: argon gas, helium, neon, nitrogen, carbon dioxide.

Description

The assay method of ferrous iron and ferric iron content in the lithium iron phosphate cathode material
Technical field
the present invention relates to the detection method of ferrous iron and ferric iron content in detection method, the especially lithium iron phosphate cathode material of cell positive material quality.
Background technology
are with respect to traditional lithium ion battery; LiFePO 4 since its to have a low price, environmental protection, Environmental compatibility good; Good cycle and high security performance more and more become the desirable energy source configuration of electric automobile, electric tool, energy storage device etc.
In lithium iron phosphate cathode material; More or less all there is iron as the trivalent of impurity; Ferric existence; The self discharge that makes lithium iron phosphate cathode material is increased, and specific storage descends, and ferric content is to weigh a good and bad important indicator of lithium iron phosphate cathode material performance.
Chinese invention patent CN200710125424.0 instructions discloses the carbon-dioxide protecting atmosphere in a kind of ferrous iron mensuration process; Said carbon-dioxide protecting atmosphere is to be generated and protected by the acid and the reaction of sodium bicarbonate that are added in the LiFePO 4; Said mensuration process just just has carbon-dioxide protecting in the sample preparation process; In processes such as sample cooling, sample transfer, sample test, all do not have protective atmosphere, inevitably cause the oxidant reaction in ferrous ion and the environment, the ferrous ion in the solution is reduced; Ferric ion increases, thereby makes the result who records depart from actual value.
Ferric iron content is trace or trace in LiFePO 4, only consumes less potassium dichromate with titration method, causes systematic error and accidental error to increase.The above-mentioned titration method of openly using, complicated operating process, the running time is longer.
With excessive stannous chloride, introduced mercury pollution in above-mentioned open middle use mercury bichloride, used potassium dichromate to carry out titration, introduced pollution of chromium, said method all can have a strong impact on environment.
Summary of the invention
That technical matters to be solved by this invention provides is that a kind of overall process is carried out in protective atmosphere, pollution-free, response speed quick, result's method accurately, to measure ferrous iron and ferric iron content in the lithium iron phosphate cathode material.Specifically may further comprise the steps:
The assay method of ferrous iron and ferric iron content in a kind of lithium iron phosphate cathode material is characterized in that: under the protective atmosphere protection, carry out sample preparation and sample determination.
Further, said sample preparation and sample determination may further comprise the steps:
Ferrous iron Determination on content: comprise lithium iron phosphate cathode material with the acid dissolving; When the PH of regulator solution is 2-9 then; Add Phen and ferrous iron generates the sample preparation process of orange complex compound and locate to measure the sample determination process of its absorbance at spectrophotometer maximum absorption wavelength (510nm);
The mensuration of ferric iron content: comprise lithium iron phosphate cathode material with the acid dissolving; When the PH of regulator solution is 1-3 then; Add sulfosalicylic acid and locate to measure the sample determination process of its absorbance with the sample preparation process of ferric iron formation violet complex with at spectrophotometer maximum absorption wavelength (549nm);
Chemical reaction mechanism in the said method is following:
Lithium iron phosphate cathode material is with acid dissolving: LiFePO 4 + 3HCl=LiCl+FeCl 2 + H 3 PO 4
Ferric iron is with acid dissolving: Fe 2 O 3 + 6HCl=2FeCl 3 + 3H 2 O
Ferrous iron and Phen generate orange complex compound: Fe 2+ + 3C1 2 H 8 N 2 =[Fe (C1 2 H 8 N 2 ) 3 ] 2+
Ferric iron and sulfosalicylic acid generate violet complex: Fe 3+ + C 7 H 6 O 6 S=[Fe (C 7 H 4 O 6 S)] + + 2H +
are further, and said protective atmosphere is provided by the protective atmosphere device, and said sample preparation and sample determination process are accomplished in the protective atmosphere device.Said atmosphere protection device is drawn together draft tube, gas outlet, casing, operating space and operation gloves, and said operating space charges into inert gas, as: argon gas, helium, neon, nitrogen, carbon dioxide etc.One side of said protective atmosphere device has the transparent operation panel of handled easily personnel operational testing and observing response in the operating space, and said gloves are the butyl gloves.
said protective atmosphere device is by draft tube; Gas outlet; Casing, airtight inert gas system of the common composition of operation gloves and inert gas, draft tube constantly charges into inert gas in case is stopped; Gas outlet is discharged unnecessary gas, keeps the positive pressure environment in the protective atmosphere device.
are further; The gas outlet of said protective atmosphere device feeds in the water; So that the protective atmosphere device is formed water seal; Avoid in the gas access to plant in the external environment, inert gas atmosphere is stable in the protective device, avoids simultaneously the waste gas in the device is directly entered atmosphere.
are further, insert the spectrophotometer that needs test usefulness in the said operating space in advance, balance, and heating arrangement, volumetric flask is claimed liquid pipe etc.
are further, and reagent related among the present invention is all handled through deoxygenation in the protective atmosphere device before use.
are further; The inventive method places the protective atmosphere device to carry out whole measuring process; Thereby the whole process from sample dissolution to spectrophotometric mensuration is all carried out under the protection of inert atmosphere; Avoided contacting of oxidizing atmosphere in ferrous ion and the atmospheric environment, thereby also avoided ferrous ion to be oxidized to ferric ion, made the result that records ferrous ion and the ferric ion content in can the actual response sample.
are further, and the inventive method is used the volumetric flask volumetric solution, uses the complex compound chelated iron ion, and AAS replaces artificial judgement with instrument test simultaneously, and finding speed easy and simple to handle is fast, thereby more accurate, and is quick, efficient.
titration method is suitable for the higher constant sample test of content; AAS is sensitive high; Reach 10-5 ~ 10-6mol/l, be suitable for the sample test of trace or trace, the inventive method is the characteristics of trace or trace to ferric iron content in the LiFePO 4; Select the AAS test for use, the error that can effectively avoid titration method to bring.
Advantage of the present invention is:
1. use super-sensitive spectrophotometer instrument test iron content, response speed is faster, efficient, and the result is more accurate;
2. use protective atmosphere device provided by the invention, make the result more accurately and reliably;
High pollution metallic element compound is not 3. used in , therefore pollution-free, more environmental protection.
Description of drawings
Fig. 1 is a protective atmosphere device synoptic diagram
wherein: 1, casing, 2, gloves, 3, the operating space, 4, the item transfer cabin, 5, draft tube, 6, transparent panel, 7, gas outlet.
Embodiment
Ferrous iron Determination on content (Phen AAS)
, the protective atmosphere device of the present invention of argon shield atmosphere carries out following experiment test in being provided:
1.1 ferrous iron solution preparation:
The first step: take by weighing LiFePO 4 Sample 0.5000 g washes wall of cup with low amounts of water in beaker, add 40 ml hydrochloric acid (1:1), and the cover upper surface ware places and is heated to little boiling on the low-temperature furnace.After keeping 20 min, take off and be cooled to room temperature, filter, filtrating moves in the 100 ml volumetric flasks and adds the water constant volume.
second step:, in the volumetric flask of 1000 ml, add the above-mentioned first step gained of 1.0 ml solution according to the iron content of estimating in the sample.
the 3rd step: be diluted with water to 60 ml; Using hydrochloric acid solution to transfer to PH is 3 (special pH test paper detections); Add buffer solution 20 ml (acetate-sodium acetate solution) of PH=4.5 and Phen solution 10 ml of 1 g/l then; Be diluted with water to scale and shake up, placement is no less than 15 min.
Selecting light path for use is that the cuvette of 1cm locates to measure its absorbance at spectrophotometer maximum absorption wavelength (510nm);
The above-mentioned Phen AAS of 1.2 usefulness is measured the iron ammonium sulfate standard solution absorbance of variable concentrations, and further draws out the typical curve of ferrous salt concentration-absorbance.
Data processing:
Fe (II) content is tried to achieve by typical curve in , and further calculates ferrous content in the sample.
The mensuration of ferric iron content (sulfosalicylic acid AAS)
, the protective atmosphere device of the present invention of argon shield atmosphere carries out following experiment test in being provided:
2.1 iron content sample solution preparation:
The first step: take by weighing LiFePO 4 Sample 2.0000 g wash wall of cup with low amounts of water in beaker, add 40 ml hydrochloric acid (1:1), and the cover upper surface ware places and is heated to little boiling on the low-temperature furnace.After keeping 20 min, take off and be cooled to room temperature, filter, filtrating moves in the 100 ml volumetric flasks and adds the water constant volume.
second step:, in the volumetric flask of 100 ml, add the above-mentioned first step gained of 1.0 ml solution according to the iron content of estimating in the sample.
the 3rd step: in above-mentioned solution, add 10% sulfosalicylic acid (SA) WS, 2 ml, add a certain amount of PH=1.5 hydrochloric acid solution, be diluted with water to scale.
Selecting light path for use is that the cuvette of 1cm locates to measure its absorbance at spectrophotometer maximum absorption wavelength (549nm);
The above-mentioned sulfosalicylic acid AAS of 2.2 usefulness is measured the iron ammonium sulfate standard solution absorbance of variable concentrations, and further draws out the typical curve of trivalent iron salt concentration-absorbance.
Data processing:
Fe (III) content is tried to achieve by typical curve in , and further calculates ferric content in the sample.
, in lithium iron phosphate cathode material, add conductive carbon, PVDF, NMP and close the slurry coating and make battery pole piece, and further make battery, carry out capacity and self discharge electrochemical property test.
Table one: iron content and electric performance test data in the LiFePO 4:
Sequence number Fe 2+ (%) Fe 3+ (%) Self discharge (%) Capacity (mAh/g)
1 35.06 0.43 2.3 138
2 35.47 0.02 0.1 151
can be found out by table one data: the more lithium iron phosphate cathode material self discharge of ferric iron content is bigger, and capacity is lower.Adopt the inventive method to measure ferrous iron and ferric content, can judge the performance of lithium iron phosphate cathode material, thereby helping further instructing produces.

Claims (3)

1. the assay method of ferrous iron and ferric iron content in the lithium iron phosphate cathode material is characterized in that: under protective atmosphere, carry out sample preparation and sample determination.
2. assay method according to claim 1 is characterized in that: said method comprising the steps of:
Ferrous iron Determination on content: lithium iron phosphate cathode material is dissolved with acid; When the PH of regulator solution is 2-9 then; Add Phen and ferrous iron and generate orange complex compound; Measure its absorbance in spectrophotometer maximum absorption wave strong point, draw ferrous content based on absorbance-ferrous iron concentration standard curve figure;
The mensuration of ferric iron content: lithium iron phosphate cathode material is dissolved with acid; When the PH of regulator solution is 1-3 then; Add sulfosalicylic acid and ferric iron and form violet complex; Measure its absorbance in spectrophotometer maximum absorption wave strong point, draw ferric content according to absorbance-ferric iron concentration canonical plotting.
3. assay method according to claim 1 is characterized in that: said protective atmosphere is provided by the protective atmosphere device, and said sample preparation and sample determination process are all accomplished in the protective atmosphere device; Said protective atmosphere device comprises draft tube, gas outlet, casing, operating space and operation gloves, and said protective atmosphere device also is provided with and can supplies operating personnel to observe the transparent panel of operating space internal reaction phenomenon; Said operating space charges into inert gas, and one or more form said inert gas by argon gas, helium, neon, nitrogen, carbon dioxide.
CN201110168693A 2011-06-22 2011-06-22 The assay method of ferrous iron and ferric iron content in the lithium iron phosphate cathode material Pending CN102323228A (en)

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Cited By (14)

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CN102866124A (en) * 2012-09-14 2013-01-09 天津力神电池股份有限公司 Method for testing Fe<3+> content of lithium iron phosphate
CN102993196A (en) * 2012-12-20 2013-03-27 北京科技大学 Triazole derivative, preparation method thereof, nano particles thereof and application of nano particles
CN103226099A (en) * 2013-03-25 2013-07-31 常州大学 Method for determining content of ferric iron in lithium iron phosphate
CN103528973A (en) * 2012-07-04 2014-01-22 北京当升材料科技股份有限公司 Method for precisely detecting phosphorus content and iron content of iron phosphate
CN105842266A (en) * 2016-03-23 2016-08-10 合肥国轩高科动力能源有限公司 Fluorescence analysis method for measuring element content of lithium iron phosphate
CN106018393A (en) * 2016-05-16 2016-10-12 广东省微生物研究所 Method for rapidly determining availability of gambiered Guangdong gauze covering river mud
CN104483305B (en) * 2014-12-02 2017-01-18 江苏元景锂粉工业有限公司 Method for determining content of carbon in lithium iron phosphate
CN108931520A (en) * 2018-10-12 2018-12-04 安徽新芜精密装备制造产业技术研究院有限公司 The measuring method and its application of impurity iron content in a kind of zirconium aluminium powder
CN109490563A (en) * 2018-10-18 2019-03-19 中国海洋大学 A kind of sampling device for solubilised state divalent Fe and Ti in seawater
CN109752375A (en) * 2019-03-18 2019-05-14 天津市环境保护科学研究院 A kind of device and method of real-time detection ferrous ion concentration
CN113267489A (en) * 2021-05-10 2021-08-17 焦作金叶醋酸纤维有限公司 Method for detecting iron ions in slurry
CN113358714A (en) * 2021-03-24 2021-09-07 厦门厦钨新能源材料股份有限公司 Method for testing content of ferric iron in lithium iron phosphate
CN113702365A (en) * 2021-07-27 2021-11-26 厦门大学深圳研究院 Method for measuring content of ferric ions in aqueous solution
CN114563537A (en) * 2022-04-29 2022-05-31 瑞浦兰钧能源股份有限公司 Method for rapidly judging cycle life of lithium iron phosphate battery

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Cited By (17)

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Publication number Priority date Publication date Assignee Title
CN103528973A (en) * 2012-07-04 2014-01-22 北京当升材料科技股份有限公司 Method for precisely detecting phosphorus content and iron content of iron phosphate
CN102866124A (en) * 2012-09-14 2013-01-09 天津力神电池股份有限公司 Method for testing Fe<3+> content of lithium iron phosphate
CN102993196A (en) * 2012-12-20 2013-03-27 北京科技大学 Triazole derivative, preparation method thereof, nano particles thereof and application of nano particles
CN102993196B (en) * 2012-12-20 2015-01-28 北京科技大学 Triazole derivative, preparation method thereof, nano particles thereof and application of nano particles
CN103226099A (en) * 2013-03-25 2013-07-31 常州大学 Method for determining content of ferric iron in lithium iron phosphate
CN104483305B (en) * 2014-12-02 2017-01-18 江苏元景锂粉工业有限公司 Method for determining content of carbon in lithium iron phosphate
CN105842266A (en) * 2016-03-23 2016-08-10 合肥国轩高科动力能源有限公司 Fluorescence analysis method for measuring element content of lithium iron phosphate
CN106018393A (en) * 2016-05-16 2016-10-12 广东省微生物研究所 Method for rapidly determining availability of gambiered Guangdong gauze covering river mud
CN108931520A (en) * 2018-10-12 2018-12-04 安徽新芜精密装备制造产业技术研究院有限公司 The measuring method and its application of impurity iron content in a kind of zirconium aluminium powder
CN109490563A (en) * 2018-10-18 2019-03-19 中国海洋大学 A kind of sampling device for solubilised state divalent Fe and Ti in seawater
CN109752375A (en) * 2019-03-18 2019-05-14 天津市环境保护科学研究院 A kind of device and method of real-time detection ferrous ion concentration
CN113358714A (en) * 2021-03-24 2021-09-07 厦门厦钨新能源材料股份有限公司 Method for testing content of ferric iron in lithium iron phosphate
CN113358714B (en) * 2021-03-24 2024-03-19 厦门厦钨新能源材料股份有限公司 Method for testing content of ferric iron in lithium iron phosphate
CN113267489A (en) * 2021-05-10 2021-08-17 焦作金叶醋酸纤维有限公司 Method for detecting iron ions in slurry
CN113702365A (en) * 2021-07-27 2021-11-26 厦门大学深圳研究院 Method for measuring content of ferric ions in aqueous solution
CN114563537A (en) * 2022-04-29 2022-05-31 瑞浦兰钧能源股份有限公司 Method for rapidly judging cycle life of lithium iron phosphate battery
CN114563537B (en) * 2022-04-29 2023-02-24 瑞浦兰钧能源股份有限公司 Method for rapidly judging cycle life of lithium iron phosphate battery

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Application publication date: 20120118