[go: up one dir, main page]
More Web Proxy on the site http://driver.im/

CN114551973B - Low-temperature type long-circulation lithium iron phosphate battery - Google Patents

Low-temperature type long-circulation lithium iron phosphate battery Download PDF

Info

Publication number
CN114551973B
CN114551973B CN202111602082.3A CN202111602082A CN114551973B CN 114551973 B CN114551973 B CN 114551973B CN 202111602082 A CN202111602082 A CN 202111602082A CN 114551973 B CN114551973 B CN 114551973B
Authority
CN
China
Prior art keywords
iron phosphate
lithium iron
low
electrolyte
nanospheres
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.)
Active
Application number
CN202111602082.3A
Other languages
Chinese (zh)
Other versions
CN114551973A (en
Inventor
谭建华
华一峰
吴家甫
吴永明
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.)
Hangzhou Huahong Communications Equipment Co ltd
Original Assignee
Hangzhou Huahong Communications Equipment Co ltd
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 Hangzhou Huahong Communications Equipment Co ltd filed Critical Hangzhou Huahong Communications Equipment Co ltd
Priority to CN202111602082.3A priority Critical patent/CN114551973B/en
Publication of CN114551973A publication Critical patent/CN114551973A/en
Application granted granted Critical
Publication of CN114551973B publication Critical patent/CN114551973B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Nanotechnology (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

The invention relates to the technical field of lithium iron phosphate batteries, and discloses a low-temperature long-cycle lithium iron phosphate battery which comprises a positive plate, a negative plate and electrolyte, wherein the positive plate comprises a positive current collector and positive slurry coated on the positive current collector; the positive electrode slurry comprises lithium iron phosphate and porous g-C 3 N 4 Nanospheres, graphene, and polymer solid electrolytes; the negative plate comprises a negative current collector and negative slurry coated on the negative current collector; the negative electrode slurry comprises natural graphite, a conductive agent and a binder; the electrolyte comprises an organic solvent, lithium salt, a film-forming additive and a low-temperature additive; the organic solvent includes nonaqueous organic solvents that do not dissolve lithium salts and carboxylic acid ester solvents. The components and the proportion thereof in the electrolyte can optimize the SEI film and can also improve the low-temperature discharge and long-cycle performance of the battery; the positive plate and the electrolyte are matched to promote ionization of lithium salt, so that the cycle performance and the service life of the battery are improved.

Description

Low-temperature type long-circulation lithium iron phosphate battery
Technical Field
The invention relates to the technical field of lithium iron phosphate batteries, in particular to a low-temperature long-cycle lithium iron phosphate battery.
Background
At present, domestic lithium ion battery anode materials are mainly concentrated in lithium manganate, ternary lithium and lithium iron phosphate, wherein the lithium iron phosphate has the advantages of good cycle stability, high safety, rich raw material sources, no toxic metal and the like, and is considered as one of the materials with the most development prospect in the existing anode materials. In recent years, lithium iron phosphate power batteries are favored by global lithium battery experts by the advantages of absolute safety, reliability, ultra-long cycle life, stable discharge platform and the like, and have rapidly developed. The lithium iron phosphate power battery can be said to completely solve the potential safety hazard problem of lithium cobalt oxide and lithium manganate batteries, and lead the industry of Chinese lithium batteries to move to a new era. Particularly, the lithium iron phosphate power battery 1C has excellent cycle performance, and compared with other traditional lithium ion batteries, the lithium iron phosphate power battery 1C has the discharge use time as long as 2000 times, and the capacity retention rate is not lower than 80 percent.
However, the lithium iron phosphate battery has certain defects and poor low-temperature performance, so that the lithium iron phosphate battery cannot be used in a relatively cold area, and the large-scale commercial popularization and application of the lithium iron phosphate battery are limited to a certain extent. In order to solve the problem, the application field of the lithium iron phosphate battery is further widened, and the low-temperature discharge performance of the lithium iron phosphate battery is urgently required to be improved. In addition, the energy density of the lithium iron phosphate battery is low, and the energy density can be improved by increasing the compacted density of the anode and cathode films. However, the lithium ion diffusion is difficult, and the wettability between the electrode plate and the electrolyte is poor, so that the cycle life of the lithium iron phosphate battery is reduced. The Chinese patent publication No. CN106450436B discloses a low-temperature high-energy-density lithium iron phosphate battery, wherein the anode comprises coated nanoscale lithium iron phosphate, polyvinylidene fluoride and oily carbon nanotubes; the negative electrode comprises porous silicon carbon, sodium carboxymethyl cellulose, a binder, SP-type conductive carbon black, C45-type conductive carbon black and KS-6-type conductive graphite; the electrolyte of the battery is a five-membered system functional material added with ionic liquid. The electrolyte has the defects that the wettability of the electrode plate and the electrolyte is poor, and the cycle performance of the battery is not improved.
Disclosure of Invention
The invention aims to provide a low-temperature type long-cycle lithium iron phosphate battery, which improves the low-temperature performance of the battery, solves the problem of cycle performance reduction after the compaction density of a positive plate is improved, and effectively prolongs the service life of the lithium iron phosphate battery.
The aim of the invention is achieved by the following technical scheme.
The invention provides a low-temperature long-cycle lithium iron phosphate battery, which comprises a positive plate, a negative plate and electrolyte, wherein the positive plate comprises a positive current collector and positive slurry coated on the positive current collector; the positive electrode slurry comprises lithium iron phosphate and porous g-C 3 N 4 Nanospheres, graphene, and polymer solid electrolytes; the negative plate comprises a negative current collector and negative slurry coated on the negative current collector; the negative electrode slurry comprises natural graphite, a conductive agent and a binder; the electrolyte comprises an organic solvent, lithium salt, a film-forming additive and a low-temperature additive; the organic solvent includes nonaqueous organic solvents that do not dissolve lithium salts and carboxylic acid ester solvents.
The positive plate has higher compaction density, and the cycle life of the whole battery can be prolonged through the cooperation of the positive plate and electrolyte. Porous g-C added in positive plate 3 N 4 The nanosphere surface has rich nitrogen atoms, so that the dissociation degree of lithium salt in the electrolyte can be increased. By polymer solid electrolyte and g-C 3 N 4 The coordination of hetero atoms such as medium oxygen, nitrogen and lithium ions promotes the ionization of lithium salt, and is uniformly dispersed on the surface of the positive plate to form a compact solid electrolyte interface film, so that the damage to the positive plate material caused by the co-intercalation of solvent molecules is avoided, and the cycle performance and the service life of the battery are greatly improved. The nonaqueous organic solvent which does not dissolve lithium salt in the electrolyte can homogenize the distribution of lithium ions in the electrolyte, and avoid high concentration gradient caused by concentrated distribution on the surface of the positive plate. However, the conductivity of the electrolyte is not good, and the carboxylate solvent can improve the conductivity and viscosity of the electrolyte and improve the wettability of the negative plate and the electrolyte.
And the freezing point of the electrolyte at low temperature is reduced by adding the low-freezing-point and low-viscosity carboxylate solvent, so that the low-temperature conductivity of the electrolyte is improved, ion migration is facilitated, and the low-temperature discharge performance of the battery is improved. The film-forming additive may promote formation of an SEI film on the surface of the negative electrode sheet, and the low-temperature additive may further optimize low-temperature discharge performance of the battery.
As a preferred alternative to this, the non-aqueous organic solvent of the insoluble lithium salt is 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether 1, 3-hexafluoroisopropyl methyl ether; the carboxylic ester solvent is one or more of methyl formate, methyl acetate, ethyl acetate, methyl propionate, methyl butyrate and ethyl butyrate.
Preferably, the volume ratio of the non-aqueous organic solvent in which the lithium salt is not dissolved to the carboxylic acid ester solvent is 60 to 85: 15-40.
The volume ratio affects the dissolution uniformity of lithium salt in the electrolyte, thereby affecting the conductivity and long cycle performance of the battery.
Preferably, the lithium salt is LiPF 6 、LiBF 4 、LiCF 3 SO 3 And LiN (CF) 2 SO 2 ) 2 One or more combinations of the above; the concentration of the lithium salt in the electrolyte is 1.2-2.0 mol/L.
Preferably, the film-forming additive comprises diethyl carbonate and vinylene carbonate; the film forming additive accounts for 7-15% of the volume fraction of the electrolyte.
The diethyl carbonate is used for improving the conductivity and the solubility of the solution, the ethylene carbonate improves the compatibility degree of the electrolyte and the negative electrode, improves the overall stability of the battery, improves the cycle of the battery and prolongs the service life of the battery. In addition, after diethyl carbonate is added, the main components of the SEI film formed in the mixed system of ethylene carbonate and diethyl carbonate are C respectively 2 H 5 COOLi and Li 2 CO 3 The SEI films formed by the two films are more stable.
Preferably, the low temperature additive comprises ethylene carbonate and fluoroethylene carbonate; the low-temperature additive accounts for 5-12% of the volume fraction of the electrolyte.
The structure of the solid phase interface film of the lithium ion battery cathode is improved by adding ethylene carbonate and fluoroethylene carbonate, the SEI low-temperature resistance is reduced, and the low-temperature discharge performance of the battery is improved. The high dielectric constant carbonate also increases the solubility of lithium salts.
Preferably, the negative electrode sheet is prepared by mixing natural graphite, a conductive agent and a binder and coating the mixture on a negative electrode current collector.
Preferably, the preparation method of the modified lithium iron phosphate positive plate comprises the following steps:
(1) SiO is made of 2 Mixing nanospheres serving as templates with melamine in water, performing ultrasonic dispersion, and performing two-step high-temperature sintering; then etching the product in hydrofluoric acid solution to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 A nanosphere;
(2) Porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methyl pyrrolidone, adding polyethylene glycol diacrylate and a photoinitiator after ultrasonic oscillation dispersion, stirring, and performing ultraviolet light initiated polymerization in an inert atmosphere; and finally adding nano lithium iron phosphate for fully homogenizing, and coating the obtained mixed slurry on a carbon-coated aluminum foil to obtain the positive plate.
The invention uses SiO 2 The nanospheres are used as templates, melamine is used as a reactant, and the surfaces of the nanospheres are sintered at high temperature to obtain SiO with a core-shell structure 2 -g-C 3 N 4 A nanosphere. And sintering at high temperature in two steps to make g-C 3 N 4 The shell layer forms a porous structure, and then the SiO is removed by etching treatment in hydrofluoric acid solution 2 Obtaining porous hollow g-C 3 N 4 A nanosphere.
Polyethylene glycol diacrylate can be used as polymer solid electrolyte to improve the conductivity and energy density of the positive plate. g-C 3 N 4 The graphite carbon nitride is added to reduce the crystallinity of the polymer solid electrolyte, form a lithium ion transmission network in a polymer matrix and effectively improve the conductivity of lithium ions. The polymer chain is inserted into g-C 3 N 4 Porous hollow structure of nanosphere, while graphene can better adsorb g-C 3 N 4 With it being present in the polymer matrix. And the hydroxyl groups rich in the surface of the graphene can be well mixed with polyethylene glycol diacrylateThereby forming a complete conductive path and improving the conductivity. The interaction force among the three can lead the lamellar structure of the graphene to generate relative micro-movement along with the movement of a molecular chain when polyethylene glycol diacrylate is crosslinked and polymerized, increase the specific surface area, provide more containing spaces of subsequent nano lithium iron phosphate particles, improve the contact area of the anode material and a conductive path, and further realize high conductivity.
In addition, porous hollow g-C 3 N 4 The nanospheres and the nano lithium iron phosphate particles are nano particles with different particle sizes, and according to the particle size proportion of the particles with different sizes, gap filling is realized, so that the compaction density of the lithium iron phosphate material is further improved, the densification of the positive electrode slurry on the surface of the positive electrode plate is realized, and the capacity and the electrochemical performance of the battery are improved.
Preferably, in step (1), the SiO 2 The grain diameter of the nanospheres is 500-600 nm.
Selecting SiO with larger particle size 2 The nanospheres can form gap filling with nano lithium iron phosphate particles, and the compaction compactness of the positive plate is good. In addition, siO with the particle size 2 The nanospheres are used as templates, and the surface g-C is not affected 3 N 4 The adhesion compactness of the shell layer ensures the formation of regular porous hollow g-C 3 N 4 A nanosphere structure.
Preferably, in the step (1), the two-step high-temperature sintering is: sintering for 1-2 h at 500-580 ℃ at a heating rate of 1-3 ℃/min; cooling to room temperature, treating for 10-30 min by using a hydrofluoric acid solution spraying method, sintering for 2-4 h at 580-650 ℃ and heating up at a speed of 2-4 ℃/min.
The first step of sintering at high temperature is to convert melamine reactant into g-C 3 N 4 Cooling to room temperature and treating with hydrofluoric acid solution to remove SiO partially 2 The shell layer is made to form a partial hollow structure. When the partial hollow structure is sintered at a high temperature in the second step, larger mesopores can be formed due to the enlarged contact area, so that better entanglement can be formed through a high molecular chain, and the intermolecular binding property is improved.
Preferably, in step (1), the SiO 2 The mass ratio of the nanospheres to the melamine is 1:1.8 to 3; the time of the mixed ultrasonic dispersion is 1-2 h; the mass fraction of hydrofluoric acid in the hydrofluoric acid solution is 4-8%, and the treatment time is 7-9 h; the porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 5-20 nm.
The porous hollow g-C formed by the invention 3 N 4 The pore diameter of the nanosphere is favorable for improving the specific surface area, forming a better penetrating structure with a high molecular chain, and not embedding nano lithium iron phosphate particles due to oversized mesopores, but is unfavorable for improving the battery capacity and exerting better conductivity.
Preferably, in step (2), the porous g-C 3 N 4 The mass ratio of the nanospheres to the graphene is 0.5-0.8: 1 to 1.3; the ultrasonic oscillation dispersion is that the ultrasonic wave is carried out for 30-70 min at 40-60 ℃ and the frequency is 100-120 kHz; the photoinitiator is 2, 2-dimethoxy-2-acetophenone; the mass ratio of the polyethylene glycol diacrylate to the photoinitiator is 1:0.3 to 0.6; the inert atmosphere is nitrogen or argon; the wavelength of the ultraviolet light is 365nm, and the intensity is 5-7 mW/cm 2 Exposing for 3-6 times, wherein the exposure time is 5-8 min each time; the particle size of the nano lithium iron phosphate is 50-100 nm; the nano lithium iron phosphate accounts for 91.5-94.5% of the mass of the mixed slurry.
The ultraviolet initiated polymerization has too short exposure time, insufficient activation of photoinitiator and the like, incomplete crosslinking reaction, too long exposure time, and excessive polymerization can cause the porous hollow g-C 3 N 4 Excessive coating of nanospheres is unfavorable for subsequent nano lithium iron phosphate and porous hollow g-C 3 N 4 Gaps formed among the nanospheres are filled, and the surface compactness of the positive plate is reduced.
Compared with the prior art, the invention has the following beneficial effects:
(1) The components and the proportion thereof in the electrolyte can optimize the SEI film and can also improve the low-temperature discharge and long-cycle performance of the battery;
(2) The positive plate and the electrolyte are matched to promote the ionization of lithium salt, and a compact solid electrolyte interface film is formed on the surface of the positive plate, so that the cycle performance and the service life of the battery are greatly improved;
(3) The preparation method of the positive plate can promote the formation of a complete conductive path and improve the conductivity; and the gap filling is realized, the compaction density of the lithium iron phosphate material is improved, and the densification of the positive plate is realized.
Detailed Description
The technical scheme of the present invention is described below by using specific examples, but the scope of the present invention is not limited thereto:
general examples
A low-temperature type long-cycle lithium iron phosphate battery comprises a positive plate, a negative plate and electrolyte. The positive plate comprises a positive current collector and positive slurry coated on the positive current collector, wherein the positive slurry comprises lithium iron phosphate and porous g-C 3 N 4 Nanospheres, graphene, and polymer solid electrolytes. The negative plate comprises a negative current collector and negative slurry coated on the negative current collector, wherein the negative slurry comprises natural graphite, a conductive agent and a binder.
The electrolyte comprises an organic solvent, lithium salt, a film forming additive and a low-temperature additive, wherein the organic solvent comprises the following components in volume ratio of 60-85: 15 to 40 non-aqueous organic solvents and carboxylic acid ester solvents which do not dissolve lithium salts. The nonaqueous organic solvent for insoluble lithium salt is 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether 1, 3-hexafluoroisopropyl methyl ether. The carboxylic ester solvent is one or more of methyl formate, methyl acetate, ethyl acetate, methyl propionate, methyl butyrate and ethyl butyrate. The lithium salt is LiPF 6 、LiBF 4 、LiCF 3 SO 3 And LiN (CF) 2 SO 2 ) 2 The concentration of lithium salt in the electrolyte is 1.2-2.0 mol/L. The film forming additive comprises diethyl carbonate and vinylene carbonate, and the film forming additive accounts for 7-15% of the volume fraction of the electrolyte. The low-temperature additive comprises ethylene carbonate and fluoroethylene carbonate, and the low-temperature additive accounts for 5-12% of the volume of the electrolyte.
The preparation method of the positive plate specifically comprises the following steps:
(1) SiO with particle diameter of 500-600 nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:1.8 to 3, after ultrasonic dispersion for 1 to 2 hours, performing two-step high-temperature sintering, and sintering for 1 to 2 hours at 500 to 580 ℃ at a heating rate of 1 to 3 ℃/min; cooling to room temperature, treating for 10-30 min by using a hydrofluoric acid solution spray method with the mass fraction of 4-8%, and sintering for 2-4 h at 580-650 ℃ with the temperature rising speed of 2-4 ℃/min; etching the product in 4-8 wt% hydrofluoric acid solution for 7-9 hr to eliminate SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 5-20 nm;
(2) The mass ratio is 0.5-0.8: 1 to 1.3 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methyl pyrrolidone, and adding the mixture into the mixture at the temperature of 40-60 ℃ and the frequency of 100-120 kHz after ultrasonic oscillation dispersion for 30-70 min, wherein the mass ratio is 1:0.3 to 0.6 of polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, and then stirring, and carrying out photoinitiated polymerization under nitrogen or argon atmosphere by using ultraviolet light with the wavelength of 365nm, wherein the intensity of the ultraviolet light is 5 to 7mW/cm 2 Exposing for 3-6 times, wherein the exposure time is 5-8 min each time; and finally, adding nano lithium iron phosphate with the particle size of 50-100 nm, fully homogenizing, and coating the obtained mixed slurry with the mass fraction of 91.5-94.5% on a carbon-coated aluminum foil to obtain the positive plate.
Example 1
A low-temperature type long-cycle lithium iron phosphate battery comprises a positive plate, a negative plate and electrolyte.
The cathode plate has the mass ratio of 96:2:2, mixing and coating the natural graphite, the carbon nano tube and the CMC on a carbon-coated aluminum foil.
The electrolyte is LiPF 6 Diethyl carbonate, vinylene carbonate, ethylene carbonate and fluoroethylene carbonate were dissolved in a volume ratio of 80:20 in a mixed solvent of 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether and methyl acetate. LiPF (LiPF) 6 At a concentration of 1.7mol/L, diethyl carbonateThe volume fraction was 3%, the volume fraction of vinylene carbonate was 7%, the volume fraction of ethylene carbonate was 2%, and the volume fraction of fluoroethylene carbonate was 4%.
The preparation method of the positive plate specifically comprises the following steps:
(1) SiO with particle diameter of 580nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:2.2, after ultrasonic dispersion for 1h, performing two-step high-temperature sintering, wherein the sintering is performed for 1.5h at 550 ℃ and the heating rate is 1 ℃/min; cooling to room temperature, treating for 20min by using a hydrofluoric acid solution spray method with the mass fraction of 6%, and sintering for 3h at 630 ℃ with the heating rate of 3 ℃/min; etching the product in hydrofluoric acid solution with mass fraction of 6% for 8h to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 17nm;
(2) The mass ratio is 0.6:1.1 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 45min at 55 ℃ and 100kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.45 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet light with intensity of 6mW/cm 2 Exposing for 5 times, wherein the exposure time is 5min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the nano lithium iron phosphate with the mass fraction of 93% on a carbon-coated aluminum foil to obtain the positive plate.
Example 2
The difference from example 1 is that:
the electrolyte is LiPF 6 Diethyl carbonate, vinylene carbonate, ethylene carbonate and fluoroethylene carbonate were dissolved in a volume ratio of 70:30, 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether and methyl formate. LiPF (LiPF) 6 The concentration of (2) was 1.8mol/L, the volume fraction of diethyl carbonate was 4%, the volume fraction of vinylene carbonate was 5%, and the volume fraction of ethylene carbonate was 5%The integration amount was 5%, and the volume fraction of fluoroethylene carbonate was 6%.
Example 3
The difference from example 1 is that:
the electrolyte is LiPF 6 Diethyl carbonate, vinylene carbonate, ethylene carbonate and fluoroethylene carbonate were dissolved in a volume ratio of 76:25, 1, 3-hexafluoroisopropyl methyl ether and methyl butyrate. LiPF (LiPF) 6 The concentration of (2) was 1.4mol/L, the volume fraction of diethyl carbonate was 7%, the volume fraction of vinylene carbonate was 4%, the volume fraction of ethylene carbonate was 5%, and the volume fraction of fluoroethylene carbonate was 6%.
Example 4
The difference from example 1 is that:
the preparation method of the positive plate comprises the following steps:
(1) SiO with particle diameter of 530nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:1.8, after ultrasonic dispersion for 1h, performing two-step high-temperature sintering, wherein the sintering is performed for 1h at 520 ℃ before the heating speed is 2 ℃/min; cooling to room temperature, treating for 20min by using a hydrofluoric acid solution spray method with the mass fraction of 5%, and sintering for 2h at 640 ℃ with the heating rate of 3 ℃/min; etching the product in hydrofluoric acid solution with mass fraction of 5% for 9h to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 13nm;
(2) The mass ratio is 0.5:1.3 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 70min at 60 ℃ and 100kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.4 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet light with 5mW/cm intensity 2 Exposing for 6 times, wherein the exposure time is 5min each time; finally adding nano lithium iron phosphate with the particle size of 60nm, fully homogenizing, and obtaining the quality of the nano lithium iron phosphate in the mixed slurryThe weight fraction is 93.5%, and the positive plate is obtained by coating the positive plate on carbon-coated aluminum foil.
Example 5
The difference from example 1 is that:
the preparation method of the positive plate comprises the following steps:
(1) SiO with particle diameter of 560nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:2.6, after ultrasonic dispersion for 2 hours, performing two-step high-temperature sintering, and sintering for 1 hour at 580 ℃ before heating at a speed of 2 ℃/min; cooling to room temperature, treating for 15min by using a hydrofluoric acid solution spray method with the mass fraction of 8%, and sintering for 3h at 650 ℃ with the heating rate of 2 ℃/min; etching the product in 8% hydrofluoric acid solution for 7 hr to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 16nm;
(2) The mass ratio is 0.8:1.1 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 50min at 55 ℃ and 115kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.3 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with ultraviolet light with wavelength of 365nm and intensity of 7mW/cm 2 Exposing for 5 times, wherein the exposure time is 7min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the obtained mixed slurry with the mass fraction of the nano lithium iron phosphate of 92.5% on a carbon-coated aluminum foil to obtain the positive plate.
Comparative example 1
The difference from example 1 is that: in the electrolyte, the volume ratio of the nonaqueous organic solvent without dissolving the lithium salt to the carboxylate solvent is 40:60.
the preparation method of the electrolyte comprises the following steps:
LiPF is put into 6 Diethyl carbonate, vinylene carbonate, ethylene carbonate and fluoroethylene carbonate were dissolved in a volume ratio of 40:60, 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether andin a mixed solvent of methyl acetate. LiPF (LiPF) 6 The concentration of (2) was 1.7mol/L, the volume fraction of diethyl carbonate was 3%, the volume fraction of vinylene carbonate was 7%, the volume fraction of ethylene carbonate was 2%, and the volume fraction of fluoroethylene carbonate was 4%.
Comparative example 2
The difference from example 1 is that: in the electrolyte, the volume ratio of the nonaqueous organic solvent without dissolving the lithium salt to the carboxylate solvent is 95:5.
the preparation method of the electrolyte comprises the following steps:
LiPF is put into 6 Diethyl carbonate, vinylene carbonate, ethylene carbonate and fluoroethylene carbonate were dissolved in a volume ratio of 95:5 in a mixed solvent of 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether and methyl acetate. LiPF (LiPF) 6 The concentration of (2) was 1.7mol/L, the volume fraction of diethyl carbonate was 3%, the volume fraction of vinylene carbonate was 7%, the volume fraction of ethylene carbonate was 2%, and the volume fraction of fluoroethylene carbonate was 4%.
Comparative example 3
The difference from example 1 is that: in the positive plate, no porous hollow g-C is added 3 N 4 A nanosphere.
The preparation method of the positive plate comprises the following steps:
mixing graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 45min at 55 ℃ and 100kHz, and adding the graphene into the mixture according to the mass ratio of 1:0.45 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet light with intensity of 6mW/cm 2 Exposing for 5 times, wherein the exposure time is 5min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the nano lithium iron phosphate with the mass fraction of 93% on a carbon-coated aluminum foil to obtain the positive plate.
Comparative example 4
The difference from example 1 is that: siO in the positive plate 2 The particle size of the nanospheres was 300nm.
The preparation method of the positive plate comprises the following steps:
(1) SiO with particle diameter of 300nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:2.2, after ultrasonic dispersion for 1h, performing two-step high-temperature sintering, wherein the sintering is performed for 1.5h at 550 ℃ and the heating rate is 1 ℃/min; cooling to room temperature, treating for 20min by using a hydrofluoric acid solution spray method with the mass fraction of 6%, and sintering for 3h at 630 ℃ with the heating rate of 3 ℃/min; etching the product in hydrofluoric acid solution with mass fraction of 6% for 8h to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 14nm;
(2) The mass ratio is 0.6:1.1 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 45min at 55 ℃ and 100kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.45 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet light with intensity of 6mW/cm 2 Exposing for 5 times, wherein the exposure time is 5min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the nano lithium iron phosphate with the mass fraction of 93% on a carbon-coated aluminum foil to obtain the positive plate.
Comparative example 5
The difference from example 1 is that: siO in the positive plate 2 The particle size of the nanospheres is 700nm.
The preparation method of the positive plate comprises the following steps:
(1) SiO with particle diameter of 700nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:2.2, after ultrasonic dispersion for 1h, performing two-step high-temperature sintering, wherein the sintering is performed for 1.5h at 550 ℃ and the heating rate is 1 ℃/min; cooling to room temperature, treating for 20min by using a hydrofluoric acid solution spray method with the mass fraction of 6%, and sintering for 3h at 630 ℃ with the heating rate of 3 ℃/min; then the product is carved in hydrofluoric acid solution with the mass fraction of 6 percentEtching for 8h to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 21nm, but the pore diameters are unevenly distributed, and the collapse phenomenon of the hollow structure occurs;
(2) The mass ratio is 0.6:1.1 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 45min at 55 ℃ and 100kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.45 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet light with intensity of 6mW/cm 2 Exposing for 5 times, wherein the exposure time is 5min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the nano lithium iron phosphate with the mass fraction of 93% on a carbon-coated aluminum foil to obtain the positive plate.
Comparative example 6
The difference from example 1 is that: in the positive plate, the two-step high-temperature sintering is changed into one-step high-temperature sintering.
The preparation method of the positive plate comprises the following steps:
(1) SiO with particle diameter of 580nm 2 Mixing nanospheres as templates with melamine in water, and SiO 2 The mass ratio of the nanospheres to the melamine is 1:2.2, after ultrasonic dispersion for 1h, performing one-step high-temperature sintering, and sintering at 550 ℃ for 3h, wherein the heating rate is 1 ℃/min; etching the product in hydrofluoric acid solution with mass fraction of 6% for 8h to remove SiO 2 Sequentially filtering, washing and drying to obtain microporous g-C 3 N 4 Nanospheres, and the etching treatment does not completely remove SiO 2 ；
(2) The mass ratio is 0.6:1.1 porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methylpyrrolidone, performing ultrasonic oscillation dispersion for 45min at 55 ℃ and 100kHz, and adding the mixture into the mixture according to the mass ratio of 1:0.45 polyethylene glycol diacrylate and 2, 2-dimethoxy-2-acetophenone, stirring, and photo-initiation polymerizing under nitrogen atmosphere with 365nm ultraviolet lightThe intensity of the ultraviolet light is 6mW/cm 2 Exposing for 5 times, wherein the exposure time is 5min each time; and finally, adding nano lithium iron phosphate with the particle size of 75nm, fully homogenizing, and coating the nano lithium iron phosphate with the mass fraction of 93% on a carbon-coated aluminum foil to obtain the positive plate.
Performance testing
And placing a diaphragm between the positive plate and the negative plate, winding to form a battery core of the high-rate lithium iron phosphate battery, packaging the battery core into a shell, and injecting liquid to form the lithium iron phosphate battery. And respectively testing the long-cycle performance, the low-temperature discharge performance and the conductivity of each group of batteries and the compaction density of the positive plate.
TABLE 1 test results of long cycle performance and Low temperature discharge Performance
Table 2 conductivity and compacted density test results
Example 1 Example 4 Example 5 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6
Conductivity (mS/cm) 10.9 10.4 10.6 7.21 8.56 8.14 7.75
Density of compaction (g/cm) 3 ) 2.58 2.55 2.56 1.91 2.24 2.10 2.11
As shown in table 1, the lithium iron phosphate battery of the present invention has excellent cycle performance and low-temperature discharge performance in combination with examples 1 to 3 and comparative examples 1 to 2. This is because each component and its proportion in the electrolyte can optimize SEI film, can also improve the low-temperature discharge and long cycle performance of the battery; the positive plate and the electrolyte are matched to promote the ionization of lithium salt, and a compact solid electrolyte interface film is formed on the surface of the positive plate, so that the cycle performance and the service life of the battery are greatly improved. By combining example 1 and comparative examples 1 to 2, it is known that the addition of the nonaqueous organic solvent in which the lithium salt is not dissolved is too much unfavorable for wettability of the electrolyte with the negative electrode sheet and conductivity of the electrolyte, and also causes the compatibility of other components in the electrolyte to be lowered, which is unfavorable for exerting its low temperature performance; too little addition is not beneficial to improving the concentrated dispersion of lithium salt at the positive plate, and can cause larger concentration gradient and cycle performance reduction.
As shown in table 2, the positive electrode sheets prepared according to the present invention have high conductivity and high compacted density in combination with examples 1, 4, 5 and comparative examples 3 to 6. It is understood that the porous hollow g-C was not added in combination with example 1 and comparative example 3 3 N 4 The nanospheres will not form a complete conductive path and voids exist between the positive electrode particles, densification cannot be achieved, and the conductivity and the compacted density are significantly reduced. In combination with example 1 and comparative examples 4-5, it can be seen that SiO 2 The nanospheres have smaller particle size or larger particle size, which is not beneficial to improving conductivity and compactness. In combination with example 1 and comparative example 6, only microporous g-C was obtained by one-step high temperature sintering 3 N 4 Nanospheres, and the etching treatment does not completely remove SiO 2 The polymer chains cannot form a good interpenetration structure, the intermolecular binding property is poor, and a complete conductive path cannot be formed.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the invention, but rather is intended to cover any equivalents of the structures disclosed herein or modifications in the equivalent processes, or any application of the structures disclosed herein, directly or indirectly, in other related arts.

Claims (10)

1. A low-temperature long-cycle lithium iron phosphate battery comprises a positive plate, a negative plate and electrolyte, and is characterized in that,
the positive plate comprises a positive current collector and positive slurry coated on the positive current collector; the positive electrode slurry comprises lithium iron phosphate and porous g-C 3 N 4 Nanospheres, graphene, and polymer solid electrolytes;
the negative plate comprises a negative current collector and negative slurry coated on the negative current collector; the negative electrode slurry comprises natural graphite, a conductive agent and a binder;
the electrolyte comprises an organic solvent, lithium salt, a film-forming additive and a low-temperature additive; the organic solvent includes nonaqueous organic solvents that do not dissolve lithium salts and carboxylic acid ester solvents.
2. A low temperature long cycle lithium iron phosphate battery according to claim 1, wherein, the non-aqueous organic solvent of the insoluble lithium salt is 1H, 5H-octafluoropentyl-1, 2-tetrafluoroethyl ether 1, 2-tetrafluoroethyl-2, 3-tetrafluoropropyl ether 1, 3-hexafluoroisopropyl methyl ether; the carboxylic ester solvent is one or more of methyl formate, methyl acetate, ethyl acetate, methyl propionate, methyl butyrate and ethyl butyrate.
3. The low-temperature long-cycle lithium iron phosphate battery according to claim 2, wherein the volume ratio of the non-aqueous organic solvent without dissolving lithium salt to the carboxylic ester solvent is 60-85: 15-40.
4. The low temperature long cycle lithium iron phosphate battery of claim 1 wherein said lithium salt is LiPF 6 、LiBF 4 、LiCF 3 SO 3 And LiN (CF) 2 SO 2 ) 2 One or more combinations of the above; the concentration of the lithium salt in the electrolyte is 1.2-2.0 mol/L.
5. A low temperature, long-cycle lithium iron phosphate battery according to claim 1, wherein said film forming additive comprises diethyl carbonate and vinylene carbonate; the film forming additive accounts for 7-15% of the volume fraction of the electrolyte.
6. A low temperature long cycle lithium iron phosphate battery according to claim 1 wherein said low temperature additives include ethylene carbonate and fluoroethylene carbonate; the low-temperature additive accounts for 5-12% of the volume of the electrolyte.
7. The low-temperature long-cycle lithium iron phosphate battery according to any one of claims 1 to 6, wherein the preparation method of the positive electrode sheet comprises the following steps:
(1) SiO is made of 2 Mixing nanospheres serving as templates with melamine in water, performing ultrasonic dispersion, and performing two-step high-temperature sintering; the product is then dissolved in hydrofluoric acidEtching in liquid to remove SiO 2 Sequentially filtering, washing and drying to obtain porous hollow g-C 3 N 4 A nanosphere;
(2) Porous hollow g-C 3 N 4 Mixing nanospheres and graphene in N-methyl pyrrolidone, adding polyethylene glycol diacrylate and a photoinitiator after ultrasonic oscillation dispersion, stirring, and performing ultraviolet light initiated polymerization in an inert atmosphere; and finally adding nano lithium iron phosphate for fully homogenizing, and coating the obtained mixed slurry on a carbon-coated aluminum foil to obtain the positive plate.
8. The low-temperature long-cycle lithium iron phosphate battery according to claim 7, wherein in the step (1),
the two-step high-temperature sintering is as follows: sintering for 1-2 hours at 500-580 ℃ at a heating rate of 1-3 ℃/min; cooling to room temperature, treating for 10-30 min by using a hydrofluoric acid solution spraying method, and sintering for 2-4 h at 580-650 ℃ with a heating rate of 2-4 ℃/min.
9. The low-temperature long-cycle lithium iron phosphate battery according to claim 7, wherein in the step (1),
the SiO is 2 The particle size of the nanospheres is 500-600 nm;
the SiO is 2 The mass ratio of the nanospheres to the melamine is 1: 1.8-3;
the porous hollow g-C 3 N 4 The average pore diameter of the nanospheres is 5-20 nm.
10. The low temperature long-cycle lithium iron phosphate battery according to claim 7, wherein in the step (2),
the porous hollow g-C 3 N 4 The mass ratio of the nanospheres to the graphene is 0.5-0.8: 1-1.3;
the photoinitiator is 2, 2-dimethoxy-2-acetophenone; the mass ratio of the polyethylene glycol diacrylate to the photoinitiator is 1:0.3 to 0.6;
the wavelength of the ultraviolet light is 365nm, and the intensity is 5-7 mW/cm 2 Exposing for 3-6 times, wherein the exposure time is 5-8 min each time;
the particle size of the nano lithium iron phosphate is 50-100 nm;
the mass fraction of the nano lithium iron phosphate in the mixed slurry is 91.5-94.5%.
CN202111602082.3A 2021-12-24 2021-12-24 Low-temperature type long-circulation lithium iron phosphate battery Active CN114551973B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111602082.3A CN114551973B (en) 2021-12-24 2021-12-24 Low-temperature type long-circulation lithium iron phosphate battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111602082.3A CN114551973B (en) 2021-12-24 2021-12-24 Low-temperature type long-circulation lithium iron phosphate battery

Publications (2)

Publication Number Publication Date
CN114551973A CN114551973A (en) 2022-05-27
CN114551973B true CN114551973B (en) 2023-08-15

Family

ID=81669236

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111602082.3A Active CN114551973B (en) 2021-12-24 2021-12-24 Low-temperature type long-circulation lithium iron phosphate battery

Country Status (1)

Country Link
CN (1) CN114551973B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2024106486A (en) * 2023-01-27 2024-08-08 ウシオ電機株式会社 Method for manufacturing electrode and drying device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017190364A1 (en) * 2016-05-06 2017-11-09 深圳先进技术研究院 Secondary battery and preparation method therefor
CN109802094A (en) * 2017-11-15 2019-05-24 成都特隆美储能技术有限公司 A kind of low temperature ferric phosphate lithium cell and preparation method thereof
CN110429277A (en) * 2019-06-28 2019-11-08 合肥国轩高科动力能源有限公司 Preparation method of high-compaction high-rate lithium iron phosphate cathode material
CN112582667A (en) * 2020-04-04 2021-03-30 骆驼集团武汉新能源科技有限公司 High-power lithium ion battery for automobile start-stop power supply

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017190364A1 (en) * 2016-05-06 2017-11-09 深圳先进技术研究院 Secondary battery and preparation method therefor
CN109802094A (en) * 2017-11-15 2019-05-24 成都特隆美储能技术有限公司 A kind of low temperature ferric phosphate lithium cell and preparation method thereof
CN110429277A (en) * 2019-06-28 2019-11-08 合肥国轩高科动力能源有限公司 Preparation method of high-compaction high-rate lithium iron phosphate cathode material
CN112582667A (en) * 2020-04-04 2021-03-30 骆驼集团武汉新能源科技有限公司 High-power lithium ion battery for automobile start-stop power supply

Also Published As

Publication number Publication date
CN114551973A (en) 2022-05-27

Similar Documents

Publication Publication Date Title
CN109888290B (en) High-rate lithium ion battery, aging and formation method
Wu et al. Functional composite polymer electrolytes with imidazole modified SiO2 nanoparticles for high-voltage cathode lithium ion batteries
CN108550835B (en) Lithium iron phosphate/gel electrolyte composite positive electrode material and preparation method thereof, and solid-state lithium battery and preparation method thereof
CN109950618B (en) Solvated composite solid electrolyte and preparation method and application thereof
WO2016161920A1 (en) Composite separator and preparation method therefor, and lithium-ion battery
CN111029558A (en) Silicon-carbon composite negative electrode material with hollow core-shell structure and preparation method thereof
CN114552122A (en) Diaphragm, preparation method thereof and secondary battery
CN114551973B (en) Low-temperature type long-circulation lithium iron phosphate battery
CN117558993A (en) Preparation method and application of composite solid electrolyte membrane
CN113707858A (en) Porous carbon-silicon composite negative electrode material and preparation method thereof
CN114420995A (en) Selenium-enriched lithium selenium battery based on three-dimensional ordered porous carbon optical crystal and preparation method thereof
CN114628637B (en) Preparation method of high-conductivity lithium iron phosphate positive plate
CN110994016B (en) Polymer solid electrolyte and preparation method and application thereof
CN112382763A (en) Organic matter/silicon composite material, battery cathode obtained from organic matter/silicon composite material and preparation method of battery cathode
CN117878290A (en) Negative electrode material, preparation method, negative electrode slurry, negative electrode plate and battery
CN117059799A (en) Graphite anode material and preparation method and application thereof
CN116804138A (en) Polyacrylic acid and sodium lignin sulfonate composite binder for silicon-based negative electrode of lithium ion battery, and preparation method and application thereof
CN116825996A (en) Preparation method of silicon-carbon composite material, silicon-carbon composite material and lithium ion battery
CN116692810A (en) Preparation method of sodium iron manganese phosphate pyrophosphate positive electrode material
CN112687873B (en) Preparation method of high-specific-energy lithium battery
CN110491685B (en) Preparation method and application of graphene supercapacitor slurry
CN102924715A (en) Method for preparing double-meso-pore ordered mesoporous carbon/ polyaniline nanometer line composite materials and application thereof
CN111170294A (en) Preparation method of low-cost lithium iron phosphate composite material
CN117393756B (en) Graphene sodium composite conductive slurry and preparation method and application thereof
CN114447307B (en) Composite positive electrode material, preparation method thereof and electrochemical energy storage device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
PE01 Entry into force of the registration of the contract for pledge of patent right
PE01 Entry into force of the registration of the contract for pledge of patent right

Denomination of invention: A low-temperature type long-cycle lithium iron phosphate battery

Effective date of registration: 20231117

Granted publication date: 20230815

Pledgee: Fuyang sub branch of Bank of Hangzhou Co.,Ltd.

Pledgor: HANGZHOU HUAHONG COMMUNICATIONS EQUIPMENT CO.,LTD.

Registration number: Y2023330002703