CN105762343A - Preparation method of LiFePO4/C anode material by rheological phase method - Google Patents

Preparation method of LiFePO4/C anode material by rheological phase method Download PDF

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CN105762343A
CN105762343A CN201610236213.3A CN201610236213A CN105762343A CN 105762343 A CN105762343 A CN 105762343A CN 201610236213 A CN201610236213 A CN 201610236213A CN 105762343 A CN105762343 A CN 105762343A
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lifepo
graphene
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electrode material
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郑叶芳
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    • 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
    • H01M4/362—Composites
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/136—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
    • H01M4/13—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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • 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

Abstract

The invention relates to an anode material for a lithium ion battery, in particular to a preparation method of a LiFePO4/C anode material by a rheological phase method.The preparation method, taking iron phosphate, lithium carbonate, glucose and graphene as raw materials, particularly includes mixing and grinding the iron phosphate and the lithium carbonate for more than 2 hours to obtain a tiny uniform solid mixture, adding a proper quantity of graphene into the solid mixture with stirring for more than 1 hour, adding a 10-20% (by mass) glucose solution with sufficiently mixing to obtain slurry, heating the slurry in a tube furnace to 700-720 DEG C, maintaining 700-720 DEG C for 8-9 hours, and naturally cooling to room temperature so as to obtain the LiFePO4/C anode material.Addition of the graphene makes the LiFePO4/C anode material small in grain size and excellent in electric conductivity, so that rate capability is improved.

Description

A kind of LiFePO4The Rheological Phase Method preparation method of/C positive electrode material
Technical field
The present invention relates to a kind of anode material for lithium-ion batteries, particularly to a kind of LiFePO4/ C positive pole The Rheological Phase Method preparation method of material.
Background technology
Along with social economy, the development of science and technology, the existing energy has been not enough to support following holding Supervention exhibition, people need to tap a new source of energy the most urgently.Lithium ion battery tool in many new forms of energy Standby high storage energy density；Service life is long, can reach more than 6 years；High (the monomer work of rated voltage It is 3.7V or 3.2V as voltage), be equivalent to the series winding voltage of 3 NI-Gs or nickel-hydrogen chargeable cell；Its Secondary it is also equipped with the ability that high power bears；Self-discharge rate is the lowest simultaneously, and this is prominent superior of this battery One of performance；Again and battery weight is light, under same volume, battery weight is about plumbic acid series of products weight 1/6-1/5；Lithium ion battery also has the adaptable feature of high/low temperature, it is possible at-20 DEG C--and 60 DEG C In the environment of use；Certainly, lithium ion battery environmental protection, whether produce, use and scrap, All do not contain, will not produce many advantages such as the poisonous and harmful heavy metallic elements such as any lead, mercury, cadmium yet. Sum it up, lithium ion battery has above-mentioned many advantages, it is future usage or replaces other batteries Only choosing.Lithium ion battery be currently used in most commonly used secondary cell, generally with lithium carbonization Compound is negative material, and organic bath is electrolyte.But, it is high to there is cost in organic bath, Electric conductivity is poor, and life condition requires height, especially in the presence of inflammable, explosive potential safety hazard, causes The limitation of ion battery range.With regard to this, people combine traditional aqueous battery low cost, It is easy to the advantage produced, it is proposed that the theoretical point view of Water-soluble lithium ion battery.Utilize aqueous solution lithium from Sub-battery, as a kind of novel secondary cell, allows aqueous solution electrolysis liquid replace organic electrolyte, it is to avoid React the safety such as burning, the blast forming dendrite and being likely to result in ask because of organic electrolyte and electrode material Topic, has the biggest advantage in the competition in field such as low-voltage battery such as lead-acid battery, alkaline Mn cell etc..
The main preparation methods of LiFePO4 has at present: Rheological Phase Method, high temperature solid-state method, carbon thermal reduction Method, microwave process for synthesizing, sol-gel process, coprecipitation, hydrothermal synthesis method etc..Rheological phase method In conjunction with solid phase reaction and liquid reactive advantage, reduce energy consumption, also reduce the particle size of product, Be suitable to industrialized production, the LiFePO4 of Rheological Phase Method synthesis, the particle diameter less due to it and have very Good conductance；Simple to operate and the process route of high temperature solid-state method is single, and technological parameter is easily controlled, The material settling out of preparation, it is easy to accomplish large-scale industrial production, but the lithium iron phosphate particles obtained Uneven, crystalline form is random, and calcining heat is the highest simultaneously, consumes energy the biggest；The production of carbothermic method Process is relatively simple, and production cost is reduced, and the electric conductivity of material makes moderate progress, but this kind of method The material of preparation and high temperature solid-state method are on the low side in terms of material capacity performance and high rate performance by contrast； The microwave process for synthesizing heat time is short, and firing rate is fast, and heat utilization rate is high, but large-scale production has one Fixed difficulty；Sol-gel process and coprecipitation have similarity, prepared material to a certain extent Activity is big, granularity is little and even particle size distribution, and heat treatment temperature reduces, and heat treatment time shortens, energy Consumption has reduced, but sol-gel process preparation condition is harsh, and particle is easily being dried and calcined Journey is lumpd, so also being difficult to expand the method in commercial Application and production thereof, and sol-gel process Preparation adds the production cost of product and the complexity of production technology simultaneously；Coprecipitation is because of difference Ingredient requirement there is similar hydrolysis or deposition condition so that it is become in the selection of raw material difficulty, Thus also have impact on its actual application；Hydro-thermal method prepare LiFePO4 have that particle diameter is little, thing is mutually homogeneous and The advantage such as easy and simple to handle, but it is only limited to the preparation of minority powder, the difficulty of industrialized production is bigger.And The shortcomings such as it is poor that LiFePO4 exists electric conductivity, and tap density is low.
Summary of the invention
The present invention provides a kind of LiFePO4/ C positive electrode material, it has less particle diameter and good electricity Conductance.
The technical solution adopted for the present invention to solve the technical problems is:
A kind of LiFePO4The Rheological Phase Method preparation method of/C positive electrode material, the method is with ferric phosphate, carbon Acid lithium, glucose and Graphene are raw material, specifically: by little with lithium carbonate mixed grinding 2 for ferric phosphate More than time, obtain uniform tiny solid mixture, this solid mixture add appropriate Graphene, Continue to grind more than 1 hour, be subsequently adding the glucose solution that mass concentration is 10%-20%, fully It is mixed to get slurry, slurry is put in tube furnace and be heated to 700-720 DEG C, maintain this temperature 8-9 little Time, naturally cool to room temperature, obtain LiFePO4/ C positive electrode material.
The present invention uses addition Graphene to strengthen the electric conductivity of LiFePO4, generates one LiFeO4The positive electrode of/C.The present invention passes through Rheological Phase Method with Fe PO4Prepare the most on year-on-year basis for raw material The LiFePO of example carbon doping4/ C positive electrode material, LiFePO prepared by Rheological Phase Method4/ C positive electrode material because of Particle diameter is less and improves conductance, and energy consumption reduces.
As preferably, after slurry is put in tube furnace, in the case of logical nitrogen, first place 20-40 Minute, heat the most again.
As preferably, ferric phosphate is 1:1.1～1.2 with the weight ratio of lithium carbonate.
As preferably, Graphene accounts for the 0.05-0.25% of described solid mixture quality.
The present invention is with Graphene as primary carbon source, and lithium carbonate, ferric phosphate and glucose are raw material, uses Rheological Phase Method prepares LiFePO4/ C positive electrode material.X-ray diffraction (XRD), scanning electron is used to show Positive electrode is characterized by the methods such as micro mirror mirror (SEM), blue electricity battery test system (LAND).Knot Fruit shows, different Graphene content is to LiFePO4Structure and the chemical property of/C positive electrode material have The biggest impact, with the LiFePO of 0.25% content Graphene synthesis4/ C positive electrode material has shown Good chemical property.This material high specific capacity under 0.1C reaches 168.5ah g-1, at high magnification 10C Under, specific capacity still has 109.4ah g-1.Under 1C, sample is through more than 50 circulations, and capacity is hardly Decay.The addition of Graphene makes LiFePO4/ C has less particle diameter and good electrical conductivity, from And improve high rate performance.
Accompanying drawing explanation
Fig. 1 is the LiFePO of different Graphene content4The XRD of/C；
Fig. 2 is the LiFePO of different Graphene content4The SEM figure of/C；
Fig. 3 is the LiFePO of different Graphene content under 0.1C4The initial charge/discharge curve map of/C；
Fig. 4 is the LiFePO of different Graphene content under 0.1C4The charging and discharging curve figure of/C；
Fig. 5 is three samples discharge cycles curve maps under different multiplying；
Fig. 6 is the LiFePO of different Graphene content under 1C4The multiple discharge cyclic curve figure of/C；
Fig. 7 is the sample C voltage and current under the 0.1C change curve with the testing time；
Fig. 8 is that sample C voltage and current under different multiplying is with testing time variation diagram；
Fig. 9 is sample C voltage and graph of relation of capacity under different multiplying；
Figure 10 is the charge and discharge cycles efficiency curve diagram of sample C under different multiplying.
Detailed description of the invention
Below by specific embodiment, technical scheme is described in further detail.Should Working as understanding, the enforcement of the present invention is not limited to the following examples, any shape being the present invention Accommodation and/or change in formula fall within scope.
In the present invention, if not refering in particular to, all of part, percentage are unit of weight, are used Equipment and raw material etc. are all commercially available or commonly used in the art.Method in following embodiment, If no special instructions, the conventional method of this area it is.
The instrument that the present embodiment part uses is:
CVD-05-20-3 type energy saving tube type stove；
Blue electrical testing system (LAND, CT2001A)；
ESEM (SPA400 Seiko In structures)；
Ad-d1 type X-ray diffractometer (Shimadzu Hiroshima company of Japan).
Embodiment 1:LiFePO4The synthesis of/C positive electrode material
With ferric phosphate (FePO4·2H2O, AR), lithium carbonate (Li2CO3, AR), glucose (C6H12O6, AR), Graphene prepares LiFePO as raw material4/ C positive electrode material.
Ferric phosphate is mixed by the weight ratio of 1:1.15 with lithium carbonate, and grinds more than 2 hours, To uniform tiny solid mixture.Be separately added into again account for described solid mixture quality 0.05%, 0.15%, the Graphene of 0.25% is in aforesaid solid mixture, continues to grind 1 hour.Take grape Sugar obtains the glucose solution that mass concentration is 20% after being dissolved in water, join in solid mixture, shape Become solid liquid fluid, i.e. a kind of slurry.Then the slurry of different Graphene content is put in tube furnace, First place 30 minutes in the case of logical nitrogen, then begin to warm up 700 DEG C, heat 8 hours, from So it is cooled to room temperature, finally gives LiFePO4/ C positive electrode material.By difference Graphene content 0.05%, 0.15%, 0.25% product obtained is labeled as A, B, C.
1, sample XRD test result analysis
X-ray is atom inner electron transition and light spoke of producing under the bombardment of high-speed motion electronics Penetrate.These very coherent scatterings produced by the atom of big figure, lewis' acid will occur the dry of light Relate to effect, thus have influence on the intensity enhancing of the X-ray of scattering or weaken.Pass through X-ray diffraction (XRD, XD-D1) and Chukka ray (λ=0.15418NM) 10 °～90 ° of scanning angles and 8°·min-1The crystal structure of each product is depicted under sweep speed.The principle of XRD: from each diffraction The angle position at peak determine spacing d of crystal face and they relative to intensity I/I1The intrinsic spy of material Levy.Each material has its specific crystal structure and unit cell dimension, and crystal structure and structure cell chi Very little have corresponding relation with the angle of diffraction, diffracted intensity again, therefore can differentiate thing by diffraction data Matter structure.By the diffractive features of unknown material phase and the diffractive features of known substance are contrasted, one by one Identify the various thing phases in sample.With ESEM (SEM, SPA400Seiko In structures) Observe particle shape and the particle diameter of sample.The operation principle of SEM: utilize focusing to obtain the thinnest height Can be scanned on sample by electron beam, inspire all kinds of physical message.By these information are connect It is subject to, amplifies and imaging, observe and obtain test sample surface topography.
Fig. 1 shows the LiFePO of different Graphene content4The X-ray diffraction image of 0 ° of/C～90 °. Compared with the standard spectrogram (PDF No.40-1499) on bibliography, the crucial diffraction maximum of three samples with Standard spectrogram coincide the most well, sample A, the equal free from admixture peak, all of peak of B, C, not detection To the diffraction maximum that remaining carbon is relevant, this well shows that residual carbon is noncrystal shape and does not interferes with LiFePO4Crystal structure and certainly sample belong to orthorhombic structure.Three samples eliminate because of impurity And the possibility causing chemical property to change, also show the authenticity of experiment and the conjunction of data simultaneously Rationality.
2, sample SEM test result analysis
Each constituent content of sample C Surface different amplification is shown in Table 1.By ESEM to graphite The LiFePO of alkene content 0.25%4The i.e. sample C of/C is tested, and Fig. 2 a and 2b is sample C table The scanning electron microscope sem image of face different amplification.It can be seen that this positive electrode is ball Type particle, granular size is more uniform, about 5-20 μm.Uniform and regular for sample C spherical Grain form will imply that one more stable structure of formation, adds uniform conductive carbon clad, has The raising mobility of effect, thus ferric phosphate lithium cell can be made to have good high rate performance.
Each constituent content table of table 1 sample C Surface different amplification
3, sample electrochemistry loop test
By above-mentioned material A, B, C are fabricated to button cell.First survey battery electricity with universal meter (UNI-T) Pressure, checks whether the button cell assembled can be used, and preliminary survey voltage >=2V is just available.Again with blue electrical measurement Battery is tested by test system (LAND, CT2001A), after connecting circuit, arranges corresponding ginseng Number.Standing under different multiplying powers (0.1C, AC), multiplying power is charged, constant-voltage charge, stands, The loop test of multiplying power discharging.Final utilization blue electricity battery test system (LAND, CT2001A) is derived Experimental data, makes all kinds of curve map, sees Fig. 3-Fig. 6.
Fig. 3 shows the LiFePO under 0.1C by different Graphene content synthesis4The initial charge and discharge of/C Electricity curve map.Understanding from curve, three samples have identical 3.4V discharge platform, but it charges Platform the most difference.Predict from first time scan round, the performance of three samples slightly difference, The performance of sample C is the best, and the performance of sample A is slightly worse.
Fig. 4 shows the LiFePO under 0.1C by different Graphene content synthesis4Stable the filling of/C Discharge curve.From figure, curve understands, so sample all has stable the filling being positioned at 3.45/3.4V Discharge platform, corresponding to Fe2+/Fe3+The steady current potential of redox, sample A, B, C are under constant current Charge specific capacity be respectively 159.8ah g-1,160.2ah·g-1, 168.5ah g-1, sample A, B, C Specific discharge capacity under constant current is respectively 154.2ah g-1, 155.1mAh g-1,159.6ah g-1, Theoretical efficiency is 103.9%, 100.2%, 100.2%, and actual efficiency is 102.7%, 99.5%, 99.7%. Because also having carried out constant-voltage charge and standing after constant-current charge so that charge specific capacity increased； Efficiency as sample A has exceeded 100%, it may be possible to owing to 0.0003V has dropped more in voltage than usual. It is it can be seen that the most sample of Graphene content shows the highest specific capacity and higher coulomb effect Rate, i.e. sample C have best conduction invertibity.LiFePO4Charge and discharge process at FePO4With LiFePO4Mutual conversion process in produce, lithium ion is from LiFePO4Electricity is entered when middle extraction and charging Xie Zhi；On the contrary, during electric discharge, lithium ion is inserted into Li from electrolyte1-xFePO4In.Sample C is uniform And the particle shape of rule will imply that one more stable structure of formation, so after de-lithium, almost All of lithium ion can be dissolved in material again, which results in the coulombic efficiency of superelevation.
Fig. 5 shows three samples discharge cycles curve map under different multiplying.See from figure, Sample C demonstrates optimal cycle performance, and its specific capacity increases with current density and decays slow Slowly.Sample A specific capacity under the multiplying power of 1C is 144.5ah g-1, its specific capacity is at 10C and 20C Multiplying power under respectively 81.9ah g-1With 3.8ah g-1, have the specific capacity of 57.1% and 3.6% to maintain respectively Rate；Sample B specific capacity under the multiplying power of 1C is 143.9mAh g-1, and its specific capacity is at 10C With respectively 84.4mAh g-1 and 6.6ah g under the multiplying power of 20C-1, have 58.6% and 4.6% respectively Specific capacity sustainment rate；Sample C specific capacity under the multiplying power of 1C is 147.3mAh g-1, and 109.4mAh g-1 and 8.5mAh g is still had in high magnification districts such as 10C and 20C-1, have respectively The specific capacity sustainment rate of 74.3% and 6.0%.[Wu Y M, Wen Z H, the Li J H.Hierarchical such as Wu Carbon-Coated LiFePO4Plate Biospheres with High Biochemical Performance For Li-Ion Batteries [J] .Advanced Materials, 2011,23 (9): 1126-1129.] successfully develop A kind of method of simplicity has synthesized the LFP/C NMS of layering, along with the value of current rate is from 0.1C The specific capacity increasing to 5C, LFP/C NMS drops to 85ah g from 150-1；Au etc. [Au R, Thong B H,Duo X D,ET AL.LiFePO4/C Composite with Excellent Rate Capability Synthesized by Archaeological Phase Method[J].Chinese Journal of Inorganic Chemistry, 2012,28 (7): 1506-1512.] with lithium carbonate as raw material, pass through rheology Phase method has synthesized lithium iron phosphate positive material, and under 5C, specific capacity is 91ah g-1；[Li Y Y, the Ca such as Li C B,Li J.Enhanced Biochemical performance of carbon atmospheres-LiFePO4 composite by PEG based sol-gel synthesis[J].Microelectronics ACT,2010, 55 (12): 3921-3926.] nanosphere-iron phosphate lithium positive pole has been synthesized by PEG group sol-gel process Material, under 5C, specific capacity is up to 113ah g-1.Compared with these three data in literature, sample A, B, the C specific capacity under the multiplying power of 5C is respectively 82.9ah g-1,83.7ah·g-1,110.5ah·g-1, Laboratory sample shows good specific capacity sustainment rate.
Fig. 6 shows the LiFePO of different Graphene content under the multiplying power of 1C4/ C positive electrode material is many Secondary charge and discharge cycles curve map.From the figure it may be seen that sample A is through probably following at 15,16 times After ring, specific discharge capacity drastically declines, only 123.8mAh g after 50 circulations-1；Sample B exists After 16 times, specific discharge capacity declines slowly, there are about 131.5mAh g after 50 circulations-1； Sample C is constantly in the stationary phase of fluctuation status, still has 142mAh g-1.According to data above, table Understand that sample C has good persistence.
From the foregoing, no matter be under the different multiplying of 0.1C, 1C, or nC, draw sample C is best, and sample A is worst, thus can prove that at identical conditions, addition The Graphene amount of carbon encapsulated material is the most, and the specific capacity of synthesized lithium iron phosphate positive material is the biggest, Chemical property is the best.Certainly, the amount that Graphene adds is in certain scope, it is also contemplated that To many influence factors, such as: the cost performance of Graphene；Specification of instrument and equipment etc..
The analysis of best sample (sample C)
1, the analysis of voltage and current
Fig. 7 shows that the voltage and current of sample C is with the change curve of testing time under 0.1C. As can be seen from Fig., the voltage and current of sample C is the most stable, has the fluctuation of regularity, The single cycle time of sample reduces lower and state is steady.
Fig. 8 shows that the voltage of sample C, electric current are with testing time change curve under different multiplying. It is seen that along with the increase of multiplying power, voltage swing fluctuation remains constant, is substantially at 3.5V, but electric current is along with the trapezoidal interim increase of change, and the single cycle testing time reduces. Compared with Fig. 7, the stability of explanation sample C voltage electric current more representative for Fig. 8 is preferable.
2, voltage and appearance quantitative analysis
Fig. 9 shows the voltage of sample C under different multiplying and the graph of relation of battery capacity.Figure In 6 kinds of multiplying powers of correspondence of 6 partial responses.It can be seen that between 1C～20C, with The increase of multiplying power, battery capacity reduces, and discharge voltage reduces, and charging voltage is always maintained at constant. Capacity with regard to this explanation sample can't reduce along with the increase of cycle-index, but can changing because of multiplying power Become and change；The electric discharge of sample is pressed and declines with the increase of multiplying power.
3, the cycle efficieny of discharge and recharge
Figure 10 shows the charge and discharge cycles efficiency curve diagram of sample C under different multiplying.Permissible from figure Finding out, sample C has the high efficiency of about 98.8% mostly, but after multiplying power is slightly made changing, effect Rate the most all compares relatively low.Because when changing multiplying power, it is to synchronize that charge specific capacity catches up with a multiplying power , and discharge-rate is to synchronize with new multiplying power, this has resulted in inefficient.Obtain from figure, sample C has high efficiency, high-performance, is a kind of preferably lithium electric material.
To sum up, Graphene and glucose are as compounded carbons, but glucose is mainly used in reduction, to material The still Graphene that material particle size and chemical property really work, is synthesized by Rheological Phase Method LiFePO4/ C positive electrode material not only has high-crystallinity, and also has less particle size and add The electric conductivity of positive electrode.For compare it, with 0.25% Graphene synthesis LiFePO4/ C has Good chemical property and electrical conductivity ability, the specific capacity when 0.1C is 159.6ah g-1, at 10C High magnification time specific capacity be 109.14mAh g-1.Reached a conclusion with comparing by the analysis of sample room, The content of Graphene is the most, LiFePO4Chemical property and the electric conductivity of/C are the strongest, discharge voltage, electricity Flow the most stable.
Embodiment described above is the one preferably scheme of the present invention, not appoints the present invention What pro forma restriction, also has other on the premise of without departing from the technical scheme described in claim Variant and remodeling.

Claims (4)

1. a LiFePO4The Rheological Phase Method preparation method of/C positive electrode material, it is characterised in that: the method with ferric phosphate, lithium carbonate, glucose and Graphene for raw material, specifically:
By ferric phosphate and lithium carbonate mixed grinding more than 2 hours, obtain uniform tiny solid mixture, this solid mixture adds appropriate Graphene, continue to grind more than 1 hour, be subsequently adding the glucose solution that mass concentration is 10%-20%, be sufficiently mixed and obtain slurry, slurry is put in tube furnace and be heated to 700-720 DEG C, maintain this temperature 8-9 hour, naturally cool to room temperature, obtain LiFePO4/ C positive electrode material.
LiFePO the most according to claim 14The Rheological Phase Method preparation method of/C positive electrode material, it is characterised in that: after slurry is put in tube furnace, first place 20-40 minute in the case of logical nitrogen, heat the most again.
LiFePO the most according to claim 14The Rheological Phase Method preparation method of/C positive electrode material, it is characterised in that: ferric phosphate is 1:1.1 ~ 1.2 with the weight ratio of lithium carbonate.
LiFePO the most according to claim 14The Rheological Phase Method preparation method of/C positive electrode material, it is characterised in that: Graphene accounts for the 0.05-0.25% of described solid mixture quality.
CN201610236213.3A 2016-04-17 2016-04-17 Preparation method of LiFePO4/C anode material by rheological phase method Withdrawn CN105762343A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107394130A (en) * 2017-06-22 2017-11-24 南昌航空大学 The LFP raw powder's production technologies that a kind of three-dimensional porous graphene is modified
CN108933246A (en) * 2018-07-20 2018-12-04 珠海聚碳复合材料有限公司 A kind of LiFePO4-graphene in-situ composite and preparation method thereof
CN110416513A (en) * 2019-07-23 2019-11-05 中国恩菲工程技术有限公司 Preparation method, carbon silicon combination electrode and the battery comprising it of carbon-silicon composite material
CN110416513B (en) * 2019-07-23 2021-08-31 中国恩菲工程技术有限公司 Preparation method of carbon-silicon composite material, carbon-silicon composite electrode and battery comprising carbon-silicon composite electrode

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