EP3678988A1 - Procédé de production de phosphate de fer lithié revêtu de carbone particulaire, phosphate de fer lithié revêtu de carbone et ses utilisations - Google Patents

Procédé de production de phosphate de fer lithié revêtu de carbone particulaire, phosphate de fer lithié revêtu de carbone et ses utilisations

Info

Publication number
EP3678988A1
EP3678988A1 EP18766012.1A EP18766012A EP3678988A1 EP 3678988 A1 EP3678988 A1 EP 3678988A1 EP 18766012 A EP18766012 A EP 18766012A EP 3678988 A1 EP3678988 A1 EP 3678988A1
Authority
EP
European Patent Office
Prior art keywords
carbon
iron phosphate
lithium iron
content
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP18766012.1A
Other languages
German (de)
English (en)
Inventor
Mark Copley
Enrico Petrucco
Maria Elena RIVAS-VELAZCO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Johnson Matthey PLC
Original Assignee
Johnson Matthey PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Matthey PLC filed Critical Johnson Matthey PLC
Publication of EP3678988A1 publication Critical patent/EP3678988A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/30—Alkali metal phosphates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to lithium transition metal phosphate materials, their preparation and use as a cathode material in secondary lithium ion batteries.
  • Lithium metal phosphates with olivine structures have emerged as promising cathode materials in secondary lithium ion batteries.
  • Advantages of lithium metal phosphates compared with other lithium compounds include the fact that they are relatively benign environmentally, and have excellent safety properties during battery handling and operation.
  • lithium metal phosphates Relatively poor electrochemical performance of lithium metal phosphates has been attributed to their poor electronic conductivity, and their performance has been significantly improved by coating the particles with electronically conductive carbon. There remains a need for lithium metal phosphates which can be made by simple, cost effective and scalable processes, employ low cost precursors, and exhibit advantageous properties such as increased electrode density.
  • the present inventors have found that electrode density of electrodes comprising carbon-coated lithium iron phosphate can be improved by controlling the properties of the carbon-containing precursor used in their preparation.
  • the present inventors have found that it is particularly advantageous to use a polyvinyl butyral in which the butyryl content, the hydroxyl content, and/or the molecular weight are controlled to particular levels.
  • PVBs polyvinyl butyrals
  • the copolymer typically includes (e.g. consists of) vinyl alcohol residues (z), vinyl butyral residues (x) and optionally vinyl acetate residues (y).
  • the values of x, y and z in Formula I can be controlled to control the properties of the PVB.
  • the weight % of vinyl butyral residues (the residue of bracket x) is referred to as the butyryl content.
  • the weight % of vinyl alcohol residues (the residue of bracket z) is referred to as the hydroxyl content.
  • the weight % of vinyl acetate residues (the residue of bracket y) is referred to as the acetyl content.
  • the acetyl content may be the remainder after the hydroxyl content and butyryl content has been accounted for. Note that acetyl residues need not be present (i.e. the value of y may be zero). (The weight % of residues recited herein is intended to include the polymer backbone shown in Formula I.)
  • PVBs may be formed by formed by reaction of a copolymer of polyvinyl alcohol and polyvinyl acetate with butyraldehyde, or by reaction of polyvinyl alcohol with butyraldehyde.
  • the properties of the PVB may also be affected by its molecular weight.
  • the present invention provides a process for producing particulate carbon-coated lithium iron phosphate, the process comprising:
  • the carbon-containing precursor is polyvinyl butyral having a butyryl content of at least 84 wt% and a hydroxyl content of 16 wt% or less.
  • the present invention provides particulate carbon-coated lithium iron phosphate obtained or obtainable by a process described herein.
  • the present invention provides use of carbon-coated lithium iron phosphate of the present invention for the preparation of a cathode of a secondary lithium ion battery.
  • the present invention provides a cathode which comprises carbon-coated lithium iron phosphate of the present invention.
  • the present invention provides a secondary lithium ion battery, comprising a cathode which comprises carbon-coated lithium iron phosphate of the present invention.
  • the battery typically further comprises an anode and an electrolyte.
  • the present invention provides a process for making particulate carbon-coated lithium iron phosphate, using polyvinyl butyral having a butyryl content of at least 84 wt% and a hydroxyl content of 16 wt% or less as a carbon-containing precursor.
  • the butyryl content is the wt% of butyryl residues in the PVB polymer and the hydroxyl content is the wt% of hydroxyl residues in the PVB polymer.
  • the PVB may optionally include acetyl residues, and the content of the acetyl residues may be the balance of the content of the PVB.
  • the sum of the acetyl content, the butyryl content and the hydroxyl content may be 100 wt%.
  • the sum of the butyryl content and the hydroxyl content may be 100 wt%.
  • the butyryl content of the PVB is at least 84 wt%.
  • the butyryl content may be at least 85 wt%, at least 86 wt%, at least 86.5 wt% or at least 87 wt%. There is not a particular upper limit on the butyryl content.
  • It may be 98 wt% or less, 95 wt% or less, 94wt% or less, 93 wt% or less, 92 wt% or less, 91 wt% or less, or 90 wt% or less.
  • the butyryl content is too low, the electrode density achievable with the resulting carbon-coated lithium iron phosphate material may be reduced.
  • the hydroxyl content of the PVB is 16 wt% or less.
  • the hydroxyl content may be 15 wt% or less, 14 wt% or less or 13 wt% or less. There is no particular lower limit on the hydroxyl content. It may be at least 1 wt%, at least 2 wt%, at least 5 wt%, at least 6 wt%, at least 7 wt%, at least 8 wt%, at least 9 wt% or at least 10 wt%. Where the hydroxyl content is too high, the electrode density achievable with the resulting carbon-coated lithium iron phosphate material may be reduced.
  • the molecular weight of the PVB is typically in the range from 80,000 to 120,000, e.g. from 90,000 to 120,000. Typically, the molecular weight distribution is such that at least 70%, at least 75%, at least 80%, at least 90% at least 95% or at least 99% (e.g. by number) of the PVB molecules have a molecular weight in the recited range.
  • the PVB typically has a viscosity of about 520 cP when determined in a 10 wt% solution in IPA (isopropyl alcohol), at a shear rate of 100 1/s.
  • the PVB may have a viscosity of at least 200 cP, at least 300 cP, at least 400 cP or at least 450 cP.
  • the PVB may have a viscosity of 800 cP or less, or 600 cP or less.
  • the particulate carbon-coated lithium iron phosphate of the present invention typically has the formula Li x Fe y P04, in which x is 0.8-1.2 and y is 0.8-1.2, and in which up to 10 atom % (e.g. up to 5 atom %) of the Fe may be replaced with a dopant metal, up to 10 atom % (e.g. up to 5 atom %) of the phosphate may be replaced with S0 4 and/or Si0 4 , and up to 10 atom % of the Li may be replaced with Na and/or K.
  • the lithium iron phosphate may have the formula LiFeP0 4 , in which up to 10 atom % (e.g.
  • the lithium iron phosphate may have the formula Li x Fe y P0 4 , in which x is 0.8-1.2 and y is 0.8-1.2.
  • the lithium iron phosphate may have the formula LiFeP0 4 .
  • the dopant metal may be one or more selected from Mn, Co, Ni, Al, Mg, Sn, Pb, Nb, B, Cu, Cr, Mo, Ru, V, Ga, Ca, Sr, Ba, Ti, Zr, Cd.
  • the dopant metal may be one or more selected from Mn, Al, Ti and Zr. It may be preferred that the lithium iron phosphate is undoped. Where the lithium iron phosphate is doped, typically dopant-containing precursor is added in the milling step.
  • the carbon-coated lithium iron phosphate is typically prepared by a process comprising a milling step and a calcination step.
  • the milling step may be a dry milling step, or may be a wet milling step, e.g. carried out in the presence of a liquid, such as water or an organic solvent. Suitable organic solvents include isopropyl alcohol, glycol ether, acetone and ethanol.
  • the milling step may be a high energy milling step.
  • high energy milling is a term well understood by those skilled in the art, to distinguish from milling or grinding treatments where lower amounts of energy are delivered.
  • high energy milling may be understood to relate to milling treatments in which at least 100kWh of energy is delivered during the milling treatment, per kilogram of solids being milled. For example, at least 150kWh, or at least 200kWh may be delivered per kilogram of solid being milled.
  • the milling energy is typically sufficient to cause mechanochemical reaction of the solids being milled.
  • lithium-containing precursors are combined and subjected to milling. If phosphorus is not provided as part of one of the iron- or lithium- containing precursors added in the milling step, a separate phosphorous-containing precursor (e.g. phosphate-containing precursor) is typically added.
  • a separate phosphorous-containing precursor e.g. phosphate-containing precursor
  • the nature of the lithium-, iron- and carbon- containing precursors is not particularly limited in the present invention. Suitable lithium-containing precursors include lithium carbonate (U2CO3), lithium hydrogen phosphate (L12HPO4) and lithium hydroxide (LiOH). L12CO3 may be preferred.
  • Suitable iron-containing precursors include iron phosphate (FePCU) and iron oxalate.
  • the iron phosphate may be hydrated (e.g. FePCU-xFbO) or may be dehydrated. FePCU may be preferred.
  • the iron-containing precursor and the lithium-containing precursor (and optionally phosphorous and / or dopant precursor) are combined in suitable proportions to give the desired stoichiometry to the lithium iron phosphate product.
  • the amount of PVB added is not particularly limited in the present invention.
  • the amount of carbon precursor may be selected to give a carbon content of 1 to 5 wt% in the carbon-coated lithium iron phosphate, e.g. 1 to 3 wt%.
  • the amount of carbon precursor added in the milling step may be in the range from 3 to 15 wt%, e.g. 3 to 7 wt%.
  • the product of the milling step is typically calcined under an inert atmosphere to provide the particulate carbon-coated lithium iron phosphate.
  • the calcination step performs two functions. Firstly, it results in pyrolysis or carbonisation of the carbon precursor to form a conductive carbon coating on the lithium iron phosphate particles.
  • the calcination is carried out in an inert atmosphere, for example in an inert gas such as argon or nitrogen. It may alternatively be carried out in a reducing atmosphere. It is typically carried out at a temperature in the range from 550°C to 800°C, e.g. from 600°C to 750°C, or from 600°C or 650°C to 700°C. 680°C is particularly suitable.
  • the calcination is carried out for a period of 3 to 24h.
  • the calcination time depends on the scale of manufacture (i.e. where larger quantities are prepared, longer calcination times may be preferred. At a commercial scale, 8 to 15 hours may be suitable, for example.
  • the process of the present invention may further comprise the step of forming an electrode (typically a cathode) comprising the carbon-coated lithium iron phosphate.
  • an electrode typically a cathode
  • this is carried out by forming a slurry of the particulate carbon-coated lithium iron phosphate, applying the slurry to the surface of a current collector (e.g. an aluminium current collector), and optionally processing (e.g. calendaring) to increase the density of the electrode.
  • the slurry may comprise one or more of a solvent, a binder, additional carbon material and further additives.
  • the electrode of the present invention will have an electrode density of at least 2.3 g/cm 3 . It may have an electrode density of 2.8 g/cm 3 or less, or 2.65 g/cm 3 or less.
  • the electrode density is the electrode density (mass/volume) of the electrode, not including the current collector the electrode is formed on. It therefore includes contributions from the active material, any additives, and additional carbon material, and any binder used.
  • the lithium iron phosphate may be capable of being formed into an electrode having an electrode density as defined above when formed into an electrode, e.g. by the electrode formation method of the Examples.
  • the process of the present invention may further comprise constructing a battery or electrochemical cell including the electrode comprising the carbon-coated lithium iron phosphate.
  • the battery or cell typically further comprises an anode and an electrolyte.
  • the battery or cell may typically be a secondary (rechargeable) lithium ion battery.
  • LiFeP0 4 L12CO3, and FeP0 4 were mixed in the desired proportions to obtain stoichiometric LiFeP0 4 , along with PVB as carbon source (at 4.5wt%).
  • the precursors were subjected to roller ball milling for 24 hours, using 10mm YSZ media.
  • the samples were then calcined in argon at 680°C for 5 hours, to form olivine lithium iron phosphate coated with conductive carbon.
  • PVBs with the properties listed below are readily available from companies including Kurarat Europe GmbH, Sigma Aldrich, Eastman Chemical and Sekisui Japan.
  • the viscosity was determined in 10 wt% solutions in I PA at a shear rate of 100 1/s.
  • the obtained lithium iron phosphate was formed into electrodes, using an electrode coating formulation.
  • the electrode coating formulation had a solids content of approximately 40% by weight.
  • the solids portion consisted of 90 wt% of active material from the Examples, 5 wt% carbon black (C65 from ImerysTM), 5 wt% binder (Solef 5130TM (polyvinylidene fluoride, 10wt% binder in n-methyl pyrrolidone).
  • the coating formulations were used to cast electrodes on a 20 ⁇ aluminium foil using a vacuum coater, to provide an electrode loading of 5 mg/cm 2 (the electrode loading refers to the mass of active material per area of electrode).
  • the coated electrodes were calendared to provide as high an electrode density as possible. The achieved electrode densities are shown in Table 2 below.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

L'invention concerne un procédé de production de phosphate de fer lithié revêtu de carbone particulaire comprenant une étape de broyage et une étape de calcination. Le procédé utilise du polyvinylbutyral ayant une teneur en butyryle d'au moins 84 % en poids et une teneur en hydroxyle de 16 % en poids ou moins en tant que précurseur contenant du carbone. Le procédé permet la formation d'électrodes ayant une densité d'électrode supérieure.
EP18766012.1A 2017-09-04 2018-08-31 Procédé de production de phosphate de fer lithié revêtu de carbone particulaire, phosphate de fer lithié revêtu de carbone et ses utilisations Withdrawn EP3678988A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB1714099.7A GB201714099D0 (en) 2017-09-04 2017-09-04 Lithium metal phosphate, its preparation and use
PCT/GB2018/052467 WO2019043401A1 (fr) 2017-09-04 2018-08-31 Procédé de production de phosphate de fer lithié revêtu de carbone particulaire, phosphate de fer lithié revêtu de carbone et ses utilisations

Publications (1)

Publication Number Publication Date
EP3678988A1 true EP3678988A1 (fr) 2020-07-15

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EP18766012.1A Withdrawn EP3678988A1 (fr) 2017-09-04 2018-08-31 Procédé de production de phosphate de fer lithié revêtu de carbone particulaire, phosphate de fer lithié revêtu de carbone et ses utilisations

Country Status (4)

Country Link
EP (1) EP3678988A1 (fr)
CN (1) CN111132928A (fr)
GB (1) GB201714099D0 (fr)
WO (1) WO2019043401A1 (fr)

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Publication number Priority date Publication date Assignee Title
CN111099570B (zh) * 2019-12-31 2023-01-13 哈尔滨万鑫石墨谷科技有限公司 一种提高LiFePO4压实密度的方法、制得的产品和用途

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CN101777636A (zh) * 2009-01-14 2010-07-14 辽宁工程技术大学 一种热解碳包覆磷酸铁锂复合材料的制备方法
US20110114875A1 (en) * 2009-11-16 2011-05-19 Guiqing Huang Electrochemically active materials and precursors thereto
CN102205954A (zh) * 2011-03-25 2011-10-05 天津恒普科技发展有限公司 一种高密度磷酸铁锂材料的合成方法
CN103427072A (zh) * 2012-05-16 2013-12-04 上海宝钢磁业有限公司 一种磷酸铁锂原位碳包覆方法
KR101580030B1 (ko) * 2013-07-09 2015-12-23 주식회사 엘지화학 탄소 코팅 리튬 인산철 나노분말의 제조방법
CN104752692B (zh) * 2013-12-30 2018-06-15 北京有色金属研究总院 一种磷酸亚铁锂/碳复合正极材料的制备方法
CN105470503A (zh) * 2014-08-08 2016-04-06 中国电子科技集团公司第十八研究所 具有均匀碳包覆层球形磷酸铁锂的制备方法
CN105655548A (zh) * 2014-12-03 2016-06-08 中国电子科技集团公司第十八研究所 一种磷酸铁锂表面均匀碳包覆的方法

Also Published As

Publication number Publication date
CN111132928A (zh) 2020-05-08
WO2019043401A1 (fr) 2019-03-07
GB201714099D0 (en) 2017-10-18

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