WO2019061674A1 - Lithium iron phosphate-containing composite negative electrode active material of lithium ion battery, composite negative electrode plate, and lithium ion battery - Google Patents

Lithium iron phosphate-containing composite negative electrode active material of lithium ion battery, composite negative electrode plate, and lithium ion battery Download PDF

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WO2019061674A1
WO2019061674A1 PCT/CN2017/109003 CN2017109003W WO2019061674A1 WO 2019061674 A1 WO2019061674 A1 WO 2019061674A1 CN 2017109003 W CN2017109003 W CN 2017109003W WO 2019061674 A1 WO2019061674 A1 WO 2019061674A1
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negative electrode
composite
silicon
active material
powder
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Chinese (zh)
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张灵志
闫晓丹
张聪聪
伊娜
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中国科学院广州能源研究所
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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
    • H01M4/36—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
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery composite anode active material, a composite anode sheet and a lithium ion battery containing lithium iron phosphate.
  • lithium-ion batteries play a pivotal role in products such as smartphones, tablets, and electric vehicles, and continue to affect people's daily lives.
  • people With the upgrading of electronic products, people have higher and higher requirements on the capacity and service life of lithium-ion batteries, which requires continuous improvement of the performance of various components of lithium-ion batteries, especially the optimization and improvement of positive and negative materials.
  • the negative electrode material currently in common use is a graphite negative electrode, and its capacity utilization rate basically reaches the upper limit value (372 mAh/g). To make the role of the negative electrode in the whole battery to a greater extent, it is necessary to use a negative electrode with a higher specific capacity.
  • the theoretical specific capacity of the silicon anode material reaches 4200 mAh/g, which is much higher than that of the graphite anode.
  • the silicon negative electrode has a lower delithiation potential ( ⁇ 0.5V), and the voltage platform of silicon is slightly higher than that of graphite. It is difficult to cause surface lithium deposition during charging, and the safety performance is higher, which is a favorable competition for the next generation lithium ion battery anode material.
  • silicon negative electrodes have natural defects. During electrochemical cycling, lithium ion deintercalation is accompanied by huge volume expansion and shrinkage (up to 300%). Constant volume change has certain stability to battery cycle performance. The effect limits the application of pure silicon materials in the negative electrode of lithium ion batteries.
  • LiFePO 4 has the advantages of low price, non-toxicity, good environmental compatibility, high specific capacity (170 mAh/g), high working voltage, long cycle life, high temperature performance and good safety performance. Positive electrode material.
  • the object of the present invention is to provide a composite anode active material of a lithium ion battery containing lithium iron phosphate, comprising lithium iron phosphate and a conventional anode material, and the electrode prepared by using the composite anode active material has a low volume. Expansion, high specific capacity, high cycle stability and excellent rate performance.
  • a composite anode active material of a lithium ion battery comprising lithium iron phosphate and a conventional anode material selected from any one of a carbon-based powder, a silicon-containing powder, or a combination thereof.
  • the lithium iron phosphate accounts for 0 to 100% by weight of the total amount of the composite negative electrode active material, but does not include 0% by weight.
  • the carbon-based powder is selected from one or a combination of artificial graphite, natural graphite, mesocarbon microbeads, petroleum coke, carbon fiber, pyrolyzed carbon, and the like.
  • the silicon-containing powder is selected from one or a combination of one or more of amorphous silicon, polycrystalline silicon, silicon oxynitride, silicon-based alloy, and silicon-carbon composite structural powder.
  • the amorphous silicon or polycrystalline silicon is in the form of nanometer or micron-sized particles; the silicon oxide oxide is in the form of micron-sized particles; the silicon-based alloy powder is a micron-sized silicon-nickel alloy; and the silicon-carbon composite structural powder The nano-silicon particle structure powder is coated with carbon.
  • the present invention also protects a composite negative electrode sheet of a lithium ion battery, a composite negative electrode active material comprising the above lithium ion battery, and a conductive agent and a binder.
  • the conductive agent is selected from one or any of acetylene black, Super P and PEDOT-PSS mixed in any ratio, and accounts for 5 to 20% by weight of the total amount of the negative electrode.
  • the binder is an oily binder polyvinylidene fluoride (PVDF), or a water-based binder polyacrylic acid (PAA), sodium polyacrylate (PAANa), styrene butadiene rubber, alginic acid, sodium alginate.
  • PVDF oily binder polyvinylidene fluoride
  • PAA water-based binder polyacrylic acid
  • PAANa sodium polyacrylate
  • styrene butadiene rubber styrene butadiene rubber
  • alginic acid sodium alginate.
  • One or any of several kinds mixed in any ratio, or one of the thickeners carboxymethyl cellulose (CMC) or sodium carboxymethyl cellulose (CMCNa) accounting for 5 to 10% by weight of the total amount of the negative electrode.
  • the active material of the composite negative electrode accounts for 70 to 90% by weight of the total amount of the negative electrode.
  • the solvent used in the preparation method is high purity deionized water or N-methylpyridinone (NMP) having a purity of 99.9%.
  • the present invention also protects a lithium ion battery comprising a composite negative electrode sheet of the above lithium ion battery.
  • the composite negative electrode sheet of the invention has low volume expansion, high specific capacity, high cycle stability and excellent rate performance, safety and pollution-free, low raw material cost, simple preparation method and suitable for industrial scale. produce.
  • Example 1 is a comparison chart of charge and discharge curves of the negative electrode half-cells prepared in Comparative Example 1, Example 1 and Example 2.
  • Example 2 is a graph showing the comparison of charge and discharge efficiency of the negative electrode half-cells prepared in Comparative Example 1, Example 1, and Example 2.
  • Example 3 is a comparison chart of the rate performance curves of the negative electrode half-cells prepared in Comparative Example 1 and Example 1.
  • Example 4 is an SEM image of the silicon-carbon composite powder used in Example 3 and Comparative Example 2.
  • Example 5 is a comparison chart of charge and discharge cycle curves of the negative electrode half-cells prepared in Example 3 and Comparative Example 2.
  • Fig. 6 is a graph showing the comparison of the first charge and discharge voltage-capacity curves of the negative electrode half-cells prepared in Examples 4-7 and Comparative Example 3.
  • Example 9 is a comparison chart of d Q/dV curves of the first charge and discharge of the negative electrode half-cells prepared in Comparative Example 1, Example 1, Example 2, and Example 8.
  • Figure 10 is a graph showing the comparison of the first charge and discharge curves of the negative electrode half-cells prepared in Example 9, Example 10 and Comparative Example 4.
  • Fig. 11 is a SEM surface top view of the negative electrode half-cell prepared in Example 11 after 100 cycles of charge and discharge cycles.
  • Fig. 12 is a SEM surface topography diagram after 100 cycles of charge and discharge cycles of the negative electrode half-cell prepared in Comparative Example 5.
  • Figure 13 is a cyclic voltammogram of the first to third revolutions of the negative half-cell prepared in Example 12.
  • Fig. 14 is a graph showing the charge and discharge cycle of the negative electrode half-cell prepared in Example 13.
  • the nano silicon powder (polysilicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then sodium carboxymethyl cellulose (CMC) is added.
  • the aqueous dispersion was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 Si/20 LFP composite electrode sheet.
  • the mass ratio of nano silicon powder, LFP, acetylene black and sodium carboxymethyl cellulose (CMC) was 50/20/20/10, respectively.
  • Electrochemical performance test The above-prepared pole piece and separator, lithium sheet, stainless steel gasket and shrapnel were stacked one on another, and the electrolyte was added dropwise to form a 2025 button lithium ion half-cell.
  • the charge and discharge performance and rate performance of the battery were tested on the Shenzhen Xinwei battery cycle test equipment.
  • the charge and discharge voltage was 0.01 to 1.5 V, and the charge and discharge current was 200 mA/g.
  • the rate performance of the battery was measured by charging and discharging at 500 mA/g, 1 A/g, 2 A/, 5 A/g, 7 A/g, and 10 A/g, and finally returning to different current densities of 500 mA/g for 10 weeks.
  • the 50S/20LFP composite electrode half-cell has a first reversible discharge specific capacity of 2937 mAh/g, and the first charge-discharge efficiency is 74%. After 100 cycles, the discharge capacity was reduced to 1415 mAh/g, and the capacity retention was 48%.
  • the negative electrode sheets of the obtained lithium ion battery were made into a half-cell in the same manner as in Example 1, and the electrochemical performance of the battery was tested on the same equipment.
  • Reference Example 1 was carried out except that the mass ratio of nano silicon powder, LFP, acetylene black and sodium carboxymethyl cellulose (CMC) was 30/40/20/10, respectively, and the obtained 30Si/40LFP composite electrode sheet.
  • CMC carboxymethyl cellulose
  • the electrochemical performance test results are shown in Fig. 1.
  • the first reversible discharge specific capacity of the 30Si/40LFP composite electrode half-cell was 2296 mAh/g, and the discharge capacity decreased to 710 mAh/g after 100 cycles, and the capacity retention rate was 31%.
  • the first charge and discharge efficiency of the 30Si/40LFP composite electrode half-cell was 71%.
  • Electrochemical performance test The above-mentioned pole piece and separator, lithium sheet, stainless steel gasket and shrapnel were stacked one on another, and the electrolyte was added dropwise to form a 2025 button lithium ion half-cell.
  • the test device was tested for charge and discharge performance and rate performance of the battery. The charge and discharge voltage was 0.01 to 1.5 V, and the charge and discharge current was 200 mA/g.
  • the rate performance of the battery was measured by charging and discharging at 500 mA/g, 1 A/g, 2 A/, 5 A/g, 7 A/g, and 10 A/g, and finally returning to different current densities of 500 mA/g for 10 weeks.
  • the results are shown in Fig. 1. It can be seen that the first reversible discharge specific capacity of the pure silicon anode half-cell reaches 2792 mAh/g, and the first charge-discharge efficiency is 76%. The discharge capacity was reduced to 597 mAh/g after 100 cycles, and the capacity retention rate was 21%.
  • Example 1 By comparing the electrochemical performance test results of Example 1, Example 2, and Comparative Example 1, as shown in FIG. 1 and FIG. 2, the addition of lithium iron phosphate powder greatly improved Si compared with the pure silicon powder anode of the lithium ion battery. Cyclic stability of the /LFP composite electrode.
  • the battery rate performance results of Comparative Example 1 and Example 1 As shown in FIG. 3, the initial discharge capacity of the pure silicon powder anode at a charge/discharge current of 500 mA/g was 2043 mAh/g, and the capacity appeared at a large current density. Rapid decay, almost no capacity at 7A / g charge and discharge current.
  • the Si/LFP composite electrode exhibits excellent rate performance, and the initial capacity reaches 3328 mAh/g at a charge/discharge current of 500 mA/g, and an initial capacity of 500 mAh/g or more at a charge/discharge current of 10 A/g.
  • the silicon carbon composite structure powder is mixed with LFP as a lithium ion battery composite negative electrode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethyl cellulose (CMC) is added.
  • the slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 SiC/20 LFP composite electrode sheet.
  • the mass ratio of the silicon-carbon composite powder, LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 50/20/20/10, respectively.
  • Figure 4 is a scanning electron micrograph of a silicon-carbon composite powder. It can be seen from the figure that carbon is uniformly coated on the surface of the silicon particles, and the diameter of the silicon-carbon composite material is about 200 nm.
  • Electrochemical performance test As shown in Fig. 5, the charge and discharge current was 500 mA/g.
  • the 50SG/20LFP composite electrode half-cell has a first reversible discharge specific capacity of 1133 mAh/g.
  • the silicon-carbon composite structural powder is used as a composite material of a lithium ion battery composite negative electrode, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added to continue grinding.
  • a uniform fluid slurry was applied to a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a SiC electrode sheet.
  • the mass ratio of the silicon carbon composite powder, acetylene black and sodium carboxymethyl cellulose (CMC) was 70/20/10, respectively.
  • Electrochemical performance test As shown in Fig. 5, the charge and discharge current was 500 mA/g. First reversible SiC electrode half-cell The specific capacity is 774mAh/g.
  • the natural graphite powder is mixed with LFP as a lithium ion battery composite anode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then a PVDF NMP dispersion is added to continue grinding into a uniform fluid slurry.
  • the slurry was coated on a copper foil by a vacuum coater, and then dried, rolled, and cut at 110 ° C to prepare an 80 G/10 LFP composite electrode sheet.
  • the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 80/10/5/5, respectively.
  • the artificial graphite powder and LFP are mixed as a lithium ion battery composite negative active material, acetylene black is added as a conductive agent, and fully ground in an agate mortar, and then the PVDF NMP dispersion is added to continue grinding into a uniform fluid slurry.
  • the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 110 ° C to prepare a 70 G/20 LFP composite electrode sheet.
  • the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 70/20/5/5.
  • the artificial graphite powder is mixed with LFP as a composite negative active material of a lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then the NMP dispersion of PVDF is added to continue grinding into a uniform fluid slurry.
  • the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 110 ° C to prepare a 60 G/30 LFP composite electrode sheet.
  • the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 60/30/5/5, respectively.
  • the artificial graphite and LFP are mixed as a composite active material of lithium ion battery composite, acetylene black is added as a conductive agent, and fully ground in an agate mortar, then the NMP dispersion of PVDF is added, and the slurry is continuously ground into a uniform fluid slurry, and vacuum is used.
  • the coater coats the slurry on a copper foil, and then vacuum-dried, rolled, and cut at 110 ° C to prepare a 50 G/40 LFP composite electrode sheet.
  • the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 50/40/5/5, respectively.
  • the natural graphite powder is used as a composite negative electrode active material of a lithium ion battery, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then the NMP dispersion of PVDF is added, and the slurry is continuously ground into a uniform fluid slurry.
  • the empty coater coats the slurry on a copper foil, and then vacuum-dried, rolled, and cut at 110 ° C to prepare a 90 G electrode sheet.
  • the mass ratio of graphite, acetylene black and polyvinylidene fluoride (PVDF) is 90/5/5.
  • Electrochemical performance test The charge and discharge voltages of the negative electrode half-cells prepared in Examples 4 to 7 and Comparative Example 3 were 0.01 to 3 V.
  • the comparison diagram of the first charge and discharge voltage-capacity curve is shown in Fig. 6.
  • the first discharge specific capacity of the pure graphite negative electrode battery was 431 mAh/g.
  • the first discharge specific capacity increases and increases as the proportion of LFP increases.
  • the first discharge specific capacities of the 80G10LFP, 70G20LFP, 60G30LFP and 50G40LFP were 502, 523, 537, 570 mAh/g.
  • Electrochemical performance test As shown in Fig. 7, the charge and discharge voltage was 0.01 to 1.5 V, the charge and discharge current was 500 mA/g, the first discharge specific capacity was 818 mAh/g, and the charge and discharge efficiency was 29%.
  • the charge and discharge voltage is 0.01 to 3 V
  • the initial charge and discharge current is 20 mA/g
  • the first discharge specific capacity is 980 mAh/g.
  • the discharge specific capacity was stabilized at 300 mAh/g.
  • the SiO2 powder is mixed with the LFP powder as a lithium ion battery composite anode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added.
  • the slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 SiO/20 LFP composite electrode sheet.
  • the mass ratio of SiO2, LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 50/20/20/10, respectively.
  • the siloxane powder is mixed with the LFP powder as a composite anode active material of a lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added.
  • CMC sodium carboxymethylcellulose
  • the SiO2 powder and the acetylene black powder were weighed, thoroughly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) was added to continue grinding to a uniform fluid slurry using a vacuum coater.
  • the slurry was coated on a copper foil, and then vacuum dried, rolled, and cut at 60 ° C to prepare a pure SiO negative electrode tab.
  • the mass ratio of silicon oxypropylene, acetylene black and sodium carboxymethyl cellulose (CMC) was 70//20/10, respectively.
  • Electrochemical performance test As shown in Fig. 10, the charge and discharge voltage was 0.01 to 3 V, and the charge and discharge current was 200 mA/g. As can be seen from Fig. 10, after the addition of LFP, the discharge specific capacity of the negative half-cell is lowered because the oxidized silicon has a higher theoretical capacity than the LFP.
  • the first charge and discharge efficiencies of the negative electrode half-cells prepared in Comparative Example 4, Example 9 and Example 10 were 54%, 52.9% and 50%, respectively, although the first discharge specific capacity and charge-discharge efficiency were reduced after the addition of LFP, Long-term cycle performance is expected to increase.
  • the nano silicon powder (amorphous silicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, fully ground in an agate mortar, and then an aqueous dispersion of sodium alginate is added.
  • the slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 Si/20 LFP composite electrode sheet.
  • the mass ratio of nano silicon powder, LFP, acetylene black and sodium alginate is 50/20/20/10, respectively.
  • the nano silicon powder (amorphous silicon) is used as an active material of the composite negative electrode of a lithium ion battery, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium alginate is added to continue grinding to uniformity.
  • the fluid slurry was coated on a copper foil with a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a Si composite electrode sheet.
  • the mass ratio of nano silicon powder, acetylene black and sodium alginate is 70/20/10 respectively.
  • nano-silica powder amorphous silicon
  • LFP powder as active materials of composite negative electrode of lithium ion battery
  • super P and PEDOT-PSS as conductive agent
  • PAA polyacrylic acid
  • the aqueous dispersion was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 20Si/70LFP composite electrode sheet.
  • the mass ratio of nano silicon powder, LFP, super P and PEDOT-PSS to polyacrylic acid was 20/70/3/2/5, respectively.
  • Electrochemical performance test The results of the first to third cycles of cyclic voltammetry of the prepared electrode are shown in FIG. The scan rate is 100 uV/s. On the first lap, two distinct oxidation peaks appeared at around 0.3V and 0.5V, respectively, and the reduction peak was at 0.2V. On the 2nd and 3rd laps, only one obvious oxidation peak was around 0.4V, and the reduction peak shifted to the left.
  • the nano silicon powder (amorphous silicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then styrene-butadiene rubber/carboxymethyl fiber is added.
  • the aqueous dispersion of sodium is continuously ground into a uniform fluid slurry, and the slurry is coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 60Si/10LFP composite electrode sheet. .
  • the mass ratio of nano silicon powder, LFP, acetylene black and styrene butadiene rubber/carboxymethyl cellulose sodium is 60/10/20/10, respectively.
  • Electrochemical performance test As shown in Fig. 14, the first reversible discharge specific capacity of the 60Si/10LFP composite electrode half-cell was 3456 mAh/g, and the first charge-discharge efficiency was 69.9%.

Abstract

A lithium iron phosphate-containing composite negative electrode active material of a lithium ion battery. The active material of the composite negative electrode comprises: lithium iron phosphate and a conventional negative electrode material. The composite negative electrode has low volumetric swelling, a high specific capacity, highly stable circulation and optimal rate performance. The battery is safe, non-polluting, and uses affordable raw materials. The preparation method is simple, easily executed and well suited for large scale industrial production.

Description

一种含有磷酸铁锂的锂离子电池复合负极活性材料、复合负极片及锂离子电池Lithium ion battery composite anode active material, composite anode sheet and lithium ion battery containing lithium iron phosphate 技术领域：Technical field:
本发明涉及锂离子电池技术领域，具体涉及一种含有磷酸铁锂的锂离子电池复合负极活性材料、复合负极片及锂离子电池。The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery composite anode active material, a composite anode sheet and a lithium ion battery containing lithium iron phosphate.
背景技术：Background technique:
自1991年全球第一只商业化锂离子电池由日本索尼推向市场以来，锂离子电池产业已经经过20多年的发展。如今，锂离子电池在智能手机、平板电脑、电动汽车等产品领域发挥着举足轻重的作用，不断影响着人们的日常生活。随着电子产品的更新换代，人们对锂离子电池的容量和使用寿命要求越来越高，这就需要不断的提高锂离子电池各个组成部件的性能，尤其是对正负极材料的优化和改善。目前普遍使用的负极材料是石墨负极，其容量利用率基本上达到上限值(372mAh/g)。如要更大程度地发挥负极在全电池中的作用，需要利用更高比容量的负极才能实现。Since the world's first commercial lithium-ion battery was introduced to the market by Sony in Japan in 1991, the lithium-ion battery industry has been developed for more than 20 years. Today, lithium-ion batteries play a pivotal role in products such as smartphones, tablets, and electric vehicles, and continue to affect people's daily lives. With the upgrading of electronic products, people have higher and higher requirements on the capacity and service life of lithium-ion batteries, which requires continuous improvement of the performance of various components of lithium-ion batteries, especially the optimization and improvement of positive and negative materials. . The negative electrode material currently in common use is a graphite negative electrode, and its capacity utilization rate basically reaches the upper limit value (372 mAh/g). To make the role of the negative electrode in the whole battery to a greater extent, it is necessary to use a negative electrode with a higher specific capacity.
硅负极材料理论比容量达到4200mAh/g，远高于石墨类负极。硅负极有较低的脱锂电位(<0.5V)，且硅的电压平台略高于石墨，在充电时难以引起表面析锂，安全性能更高，是下一代锂离子电池负极材料的有利竞争者。但是硅负极存在天然的缺陷，在电化学循环过程中，锂离子脱嵌时伴随着巨大的体积膨胀和收缩(最高可达300％)，不断的体积变化对电池循环性能的稳定性具有一定的影响，限制了纯硅材料在锂离子电池负极中的应用。The theoretical specific capacity of the silicon anode material reaches 4200 mAh/g, which is much higher than that of the graphite anode. The silicon negative electrode has a lower delithiation potential (<0.5V), and the voltage platform of silicon is slightly higher than that of graphite. It is difficult to cause surface lithium deposition during charging, and the safety performance is higher, which is a favorable competition for the next generation lithium ion battery anode material. By. However, silicon negative electrodes have natural defects. During electrochemical cycling, lithium ion deintercalation is accompanied by huge volume expansion and shrinkage (up to 300%). Constant volume change has certain stability to battery cycle performance. The effect limits the application of pure silicon materials in the negative electrode of lithium ion batteries.
LiFePO4具有价格便宜、无毒、环境相容性好、较高的比容量(170mAh/g)和较高的工作电压、循环寿命长、高温性能和安全性能好等优点，是锂离子电池常用的正极材料。LiFePO 4 has the advantages of low price, non-toxicity, good environmental compatibility, high specific capacity (170 mAh/g), high working voltage, long cycle life, high temperature performance and good safety performance. Positive electrode material.
发明内容：Summary of the invention:
本发明的目的针对现有技术存在的问题，提供一种含有磷酸铁锂的锂离子电池的复合负极活性材料，包括磷酸铁锂与常规负极材料，用该复合负极活性材料制备的电极具有低体积膨胀、高比容量、高循环稳定性以及优良的倍率性能。The object of the present invention is to provide a composite anode active material of a lithium ion battery containing lithium iron phosphate, comprising lithium iron phosphate and a conventional anode material, and the electrode prepared by using the composite anode active material has a low volume. Expansion, high specific capacity, high cycle stability and excellent rate performance.
本发明是通过以下技术方案予以实现的：The present invention is achieved by the following technical solutions:
一种锂离子电池的复合负极活性材料，所述复合负极活性材料含有磷酸铁锂与常规负极材料，所述常规负极材料选自碳基粉末、含硅粉末中的任一种或其结合。A composite anode active material of a lithium ion battery, the composite anode active material comprising lithium iron phosphate and a conventional anode material selected from any one of a carbon-based powder, a silicon-containing powder, or a combination thereof.
所述磷酸铁锂占复合负极活性材料总量的0～100wt％，但不包括0wt％。 The lithium iron phosphate accounts for 0 to 100% by weight of the total amount of the composite negative electrode active material, but does not include 0% by weight.
所述碳基粉末选自人工石墨、天然石墨、中间相碳微球、石油焦、碳纤维、热解树脂碳等粉末中的一种或其中几种的任意组合。The carbon-based powder is selected from one or a combination of artificial graphite, natural graphite, mesocarbon microbeads, petroleum coke, carbon fiber, pyrolyzed carbon, and the like.
所述含硅粉末选自非晶硅、多晶硅、氧化亚硅、硅基合金、硅碳复合结构粉末中的一种或几种的任意组合。The silicon-containing powder is selected from one or a combination of one or more of amorphous silicon, polycrystalline silicon, silicon oxynitride, silicon-based alloy, and silicon-carbon composite structural powder.
特别地，所述非晶硅、多晶硅为纳米级或微米级颗粒状；所述氧化亚硅为微米级颗粒状；所述硅基合金粉末为微米级硅镍合金；所述硅碳复合结构粉末为碳包覆纳米硅颗粒结构粉末。Specifically, the amorphous silicon or polycrystalline silicon is in the form of nanometer or micron-sized particles; the silicon oxide oxide is in the form of micron-sized particles; the silicon-based alloy powder is a micron-sized silicon-nickel alloy; and the silicon-carbon composite structural powder The nano-silicon particle structure powder is coated with carbon.
本发明还保护一种锂离子电池的复合负极片，包含上述的锂离子电池的复合负极活性材料，还包括导电剂和粘结剂。The present invention also protects a composite negative electrode sheet of a lithium ion battery, a composite negative electrode active material comprising the above lithium ion battery, and a conductive agent and a binder.
优选地，所述导电剂选自乙炔黑、Super P和PEDOT-PSS中的一种或任意几种以任意比例混合，占负极总量的5～20wt％。Preferably, the conductive agent is selected from one or any of acetylene black, Super P and PEDOT-PSS mixed in any ratio, and accounts for 5 to 20% by weight of the total amount of the negative electrode.
所述的粘结剂为油性粘结剂聚偏二氟乙烯(PVDF)，或者水系粘结剂聚丙烯酸(PAA)、聚丙烯酸钠(PAANa)、丁苯橡胶、海藻酸、海藻酸钠中的一种或任意几种以任意比例混合而成，或增稠剂羧甲基纤维素(CMC)或者羧甲基纤维素钠(CMCNa)中的一种，占负极总量的5～10wt％。The binder is an oily binder polyvinylidene fluoride (PVDF), or a water-based binder polyacrylic acid (PAA), sodium polyacrylate (PAANa), styrene butadiene rubber, alginic acid, sodium alginate. One or any of several kinds mixed in any ratio, or one of the thickeners carboxymethyl cellulose (CMC) or sodium carboxymethyl cellulose (CMCNa), accounting for 5 to 10% by weight of the total amount of the negative electrode.
优选地，所述复合负极的活性材料占负极总量的70～90wt％。Preferably, the active material of the composite negative electrode accounts for 70 to 90% by weight of the total amount of the negative electrode.
本发明还保护上述锂离子电池的复合负极片的制备方法，该方法包括以下步骤：将磷酸铁锂粉末与常规负极材料混合为锂离子电池的复合负极活性材料；加入导电剂和粘结剂分散体，经过研磨或者高速机械搅拌制备出均匀的流体浆料；将得到的流体浆料经过涂布、烘干、碾压之后，得到锂离子电池负极极片。The invention also protects the preparation method of the composite negative electrode sheet of the above lithium ion battery, which comprises the steps of: mixing lithium iron phosphate powder with a conventional negative electrode material into a composite negative active material of a lithium ion battery; adding a conductive agent and a binder to disperse The body is subjected to grinding or high-speed mechanical stirring to prepare a uniform fluid slurry; after the obtained fluid slurry is coated, dried and rolled, a negative electrode sheet of a lithium ion battery is obtained.
制备方法中用到的溶剂为高纯度去离子水或纯度99.9％的N-甲基吡硌烷酮(NMP)。The solvent used in the preparation method is high purity deionized water or N-methylpyridinone (NMP) having a purity of 99.9%.
本发明还保护一种锂离子电池，含有上述锂离子电池的复合负极片。The present invention also protects a lithium ion battery comprising a composite negative electrode sheet of the above lithium ion battery.
本发明的有益效果如下：本发明复合负极片具有低体积膨胀、高比容量、高循环稳定性以及优良的倍率性能，安全无污染，并且原料成本低，制备方法简单易行，适合工业规模化生产。The beneficial effects of the invention are as follows: the composite negative electrode sheet of the invention has low volume expansion, high specific capacity, high cycle stability and excellent rate performance, safety and pollution-free, low raw material cost, simple preparation method and suitable for industrial scale. produce.
附图说明：BRIEF DESCRIPTION OF THE DRAWINGS:
图1是对比例1、实施例1和实施例2制备的负极半电池的充放电曲线对比图。1 is a comparison chart of charge and discharge curves of the negative electrode half-cells prepared in Comparative Example 1, Example 1 and Example 2.
图2是对比例1、实施例1和实施例2制备的负极半电池的充放电效率对比图。2 is a graph showing the comparison of charge and discharge efficiency of the negative electrode half-cells prepared in Comparative Example 1, Example 1, and Example 2.
图3是对比例1和实施例1制备的负极半电池的倍率性能曲线对比图。 3 is a comparison chart of the rate performance curves of the negative electrode half-cells prepared in Comparative Example 1 and Example 1.
图4是实施例3和对比例2所用硅碳复合粉末的SEM图。4 is an SEM image of the silicon-carbon composite powder used in Example 3 and Comparative Example 2.
图5是实施例3和对比例2制备的负极半电池的充放电循环曲线对比图。5 is a comparison chart of charge and discharge cycle curves of the negative electrode half-cells prepared in Example 3 and Comparative Example 2.
图6是实施例4-7与对比例3制备的负极半电池的首次充放电电压-容量曲线对比图。Fig. 6 is a graph showing the comparison of the first charge and discharge voltage-capacity curves of the negative electrode half-cells prepared in Examples 4-7 and Comparative Example 3.
图7、8是实施例8制备的负极半电池的充放电循环曲线。7 and 8 are charge and discharge cycle curves of the negative electrode half-cell prepared in Example 8.
图9是对比例1、实施例1、实施例2和实施例8制备的负极半电池首次充放电的d Q/dV曲线对比图。9 is a comparison chart of d Q/dV curves of the first charge and discharge of the negative electrode half-cells prepared in Comparative Example 1, Example 1, Example 2, and Example 8.
图10是实施例9、实施例10和对比例4制备的负极半电池的首次充放电曲线对比图。Figure 10 is a graph showing the comparison of the first charge and discharge curves of the negative electrode half-cells prepared in Example 9, Example 10 and Comparative Example 4.
图11是实施例11制备的负极半电池的充放电循环100周后的SEM表面形貌图。Fig. 11 is a SEM surface top view of the negative electrode half-cell prepared in Example 11 after 100 cycles of charge and discharge cycles.
图12是对比例5制备的负极半电池的充放电循环100周后的SEM表面形貌图。Fig. 12 is a SEM surface topography diagram after 100 cycles of charge and discharge cycles of the negative electrode half-cell prepared in Comparative Example 5.
图13是实施例12制备的负极半电池第1-3圈循环伏安曲线图。Figure 13 is a cyclic voltammogram of the first to third revolutions of the negative half-cell prepared in Example 12.
图14是实施例13制备的负极半电池的充放电循环曲线图。Fig. 14 is a graph showing the charge and discharge cycle of the negative electrode half-cell prepared in Example 13.
具体实施方式：Detailed ways:
以下是对本发明的进一步说明，而不是对本发明的限制。The following is a further description of the invention and is not to be construed as limiting.
所有实施例和对比例的中负极极片组成成分参见表1。See Table 1 for the composition of the middle and negative pole pieces of all the examples and comparative examples.
表1Table 1
Figure PCTCN2017109003-appb-000001
Figure PCTCN2017109003-appb-000001
Figure PCTCN2017109003-appb-000002
Figure PCTCN2017109003-appb-000002
实施例1:Example 1:
将纳米硅粉(多晶硅)和LFP粉末混合作为锂离子电池的复合负极的活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成50Si/20LFP复合电极片。其中，纳米硅粉、LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为50/20/20/10。The nano silicon powder (polysilicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then sodium carboxymethyl cellulose (CMC) is added. The aqueous dispersion was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 Si/20 LFP composite electrode sheet. Among them, the mass ratio of nano silicon powder, LFP, acetylene black and sodium carboxymethyl cellulose (CMC) was 50/20/20/10, respectively.
电化学性能测试:将上述制得的极片与隔膜、锂片、不锈钢垫片和弹片依次叠放并滴加电解液后封口制成2025扣式锂离子半电池，电解液的成分为1mol LiPF6溶于EC/EMC/DEC(体积比＝1:1:1)+10wt％FEC，隔膜使用Celgard 2400。在深圳新威尔电池循环测试设备上测试电池的充放电性能及倍率性能，充放电电压为0.01～1.5V，充放电电流为200mA/g。电池的倍率性能依次通过在500mA/g、1A/g、2A/、5A/g、7A/g和10A/g，最后再回到500mA/g的不同电流密度下充放电10周测得。结果如图1所示，50Si/20LFP复合电极半电池的首次可逆放电比容量为2937mAh/g，首次充放电效率74％。100周循环后放电容量降为1415mAh/g，容量保持率为48％。Electrochemical performance test: The above-prepared pole piece and separator, lithium sheet, stainless steel gasket and shrapnel were stacked one on another, and the electrolyte was added dropwise to form a 2025 button lithium ion half-cell. The composition of the electrolyte was 1 mol LiPF. 6 Dissolved in EC/EMC/DEC (volume ratio = 1:1:1) + 10 wt% FEC, and the diaphragm used Celgard 2400. The charge and discharge performance and rate performance of the battery were tested on the Shenzhen Xinwei battery cycle test equipment. The charge and discharge voltage was 0.01 to 1.5 V, and the charge and discharge current was 200 mA/g. The rate performance of the battery was measured by charging and discharging at 500 mA/g, 1 A/g, 2 A/, 5 A/g, 7 A/g, and 10 A/g, and finally returning to different current densities of 500 mA/g for 10 weeks. As a result, as shown in Fig. 1, the 50S/20LFP composite electrode half-cell has a first reversible discharge specific capacity of 2937 mAh/g, and the first charge-discharge efficiency is 74%. After 100 cycles, the discharge capacity was reduced to 1415 mAh/g, and the capacity retention was 48%.
以下实施例均采用和实施例1相同的方法将所得锂离子电池的负极片制成半电池，且在相同设备上测试该电池的电化学性能。In the following examples, the negative electrode sheets of the obtained lithium ion battery were made into a half-cell in the same manner as in Example 1, and the electrochemical performance of the battery was tested on the same equipment.
实施例2:Example 2:
参考实施例1，不同之处在于：纳米硅粉、LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为30/40/20/10，得到的30Si/40LFP复合电极片。Reference Example 1 was carried out except that the mass ratio of nano silicon powder, LFP, acetylene black and sodium carboxymethyl cellulose (CMC) was 30/40/20/10, respectively, and the obtained 30Si/40LFP composite electrode sheet.
电化学性能测试结果如图1所示，30Si/40LFP复合电极半电池的首次可逆放电比容量为2296mAh/g，100周循环后放电容量降为710mAh/g，容量保持率为31％。如图2所示，30Si/40LFP复合电极半电池的首次充放电效率71％。The electrochemical performance test results are shown in Fig. 1. The first reversible discharge specific capacity of the 30Si/40LFP composite electrode half-cell was 2296 mAh/g, and the discharge capacity decreased to 710 mAh/g after 100 cycles, and the capacity retention rate was 31%. As shown in Fig. 2, the first charge and discharge efficiency of the 30Si/40LFP composite electrode half-cell was 71%.
对比例1：Comparative example 1:
称取纳米硅粉和乙炔黑粉末，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成纯Si负极极片。其中，纳米硅粉、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为70//20/10。Weigh the nano-silica powder and acetylene black powder, grind it thoroughly in an agate mortar, then add an aqueous dispersion of sodium carboxymethyl cellulose (CMC), continue grinding to a uniform fluid slurry, and use a vacuum coater. The slurry was coated on a copper foil, and then vacuum dried, rolled, and cut at 60 ° C to prepare a pure Si negative electrode tab. Among them, the mass ratio of nano silicon powder, acetylene black and sodium carboxymethyl cellulose (CMC) was 70//20/10, respectively.
电化学性能测试：将上述制得的极片与隔膜、锂片、不锈钢垫片和弹片依次叠放并滴加电解液后封口制成2025扣式锂离子半电池，电解液的成分为1mol LiPF6溶于EC/EMC/DEC(体积比＝1:1:1)+10wt％FEC，隔膜使用Celgard 2400。在深圳新威尔电池循环 测试设备上测试电池的充放电性能及倍率性能，充放电电压为0.01～1.5V，充放电电流为200mA/g。电池的倍率性能依次通过在500mA/g、1A/g、2A/、5A/g、7A/g和10A/g，最后再回到500mA/g的不同电流密度下充放电10周测得。结果如图1所示，从中可以看出，纯硅负极半电池的首次可逆放电比容量达到2792mAh/g，首次充放电效率76％。100周循环后放电容量降为597mAh/g，容量保持率为21％。Electrochemical performance test: The above-mentioned pole piece and separator, lithium sheet, stainless steel gasket and shrapnel were stacked one on another, and the electrolyte was added dropwise to form a 2025 button lithium ion half-cell. The composition of the electrolyte was 1 mol LiPF6. Dissolved in EC/EMC/DEC (volume ratio = 1:1:1) + 10 wt% FEC, and the diaphragm used Celgard 2400. Shenzhen Xinweier battery cycle The test device was tested for charge and discharge performance and rate performance of the battery. The charge and discharge voltage was 0.01 to 1.5 V, and the charge and discharge current was 200 mA/g. The rate performance of the battery was measured by charging and discharging at 500 mA/g, 1 A/g, 2 A/, 5 A/g, 7 A/g, and 10 A/g, and finally returning to different current densities of 500 mA/g for 10 weeks. The results are shown in Fig. 1. It can be seen that the first reversible discharge specific capacity of the pure silicon anode half-cell reaches 2792 mAh/g, and the first charge-discharge efficiency is 76%. The discharge capacity was reduced to 597 mAh/g after 100 cycles, and the capacity retention rate was 21%.
通过对实施例1、实施例2、对比例1的电化学性能测试结果的对比，如图1、2所示，相对于锂离子电池纯硅粉负极，磷酸铁锂粉末的加入大大提高了Si/LFP复合电极的循环稳定性。通过对对比例1和实施例1的电池倍率性能结果对比，如图3所示，纯硅粉负极在500mA/g充放电电流时初始放电容量为2043mAh/g，在大的电流密度下容量出现迅速衰减，7A/g充放电电流下已几乎没有容量。Si/LFP复合电极表现出优异的倍率性能，在500mA/g充放电电流时初始容量达到3328mAh/g，10A/g充放电电流下仍然有500mAh/g以上的初始容量。By comparing the electrochemical performance test results of Example 1, Example 2, and Comparative Example 1, as shown in FIG. 1 and FIG. 2, the addition of lithium iron phosphate powder greatly improved Si compared with the pure silicon powder anode of the lithium ion battery. Cyclic stability of the /LFP composite electrode. By comparing the battery rate performance results of Comparative Example 1 and Example 1, as shown in FIG. 3, the initial discharge capacity of the pure silicon powder anode at a charge/discharge current of 500 mA/g was 2043 mAh/g, and the capacity appeared at a large current density. Rapid decay, almost no capacity at 7A / g charge and discharge current. The Si/LFP composite electrode exhibits excellent rate performance, and the initial capacity reaches 3328 mAh/g at a charge/discharge current of 500 mA/g, and an initial capacity of 500 mAh/g or more at a charge/discharge current of 10 A/g.
实施例3:Example 3:
将硅碳复合结构粉末与LFP混合作为锂离子电池复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成50SiC/20LFP复合电极片。其中，硅碳复合粉末、LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为50/20/20/10。The silicon carbon composite structure powder is mixed with LFP as a lithium ion battery composite negative electrode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethyl cellulose (CMC) is added. The slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 SiC/20 LFP composite electrode sheet. Among them, the mass ratio of the silicon-carbon composite powder, LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 50/20/20/10, respectively.
SEM表面形貌测试：图4是硅碳复合粉末的扫描电镜图，从图中可以看出，碳均匀的包覆在硅颗粒表面，硅碳复合材料的直径在200nm左右。SEM surface topography test: Figure 4 is a scanning electron micrograph of a silicon-carbon composite powder. It can be seen from the figure that carbon is uniformly coated on the surface of the silicon particles, and the diameter of the silicon-carbon composite material is about 200 nm.
电化学性能测试:如图5所示，充放电电流为500mA/g。50SiC/20LFP复合电极半电池的首次可逆放电比容量为1133mAh/g。Electrochemical performance test: As shown in Fig. 5, the charge and discharge current was 500 mA/g. The 50SG/20LFP composite electrode half-cell has a first reversible discharge specific capacity of 1133 mAh/g.
对比例2:Comparative example 2:
将硅碳复合结构粉末作为锂离子电池复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成SiC电极片。其中，硅碳复合粉末、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为70/20/10。The silicon-carbon composite structural powder is used as a composite material of a lithium ion battery composite negative electrode, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added to continue grinding. A uniform fluid slurry was applied to a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a SiC electrode sheet. Among them, the mass ratio of the silicon carbon composite powder, acetylene black and sodium carboxymethyl cellulose (CMC) was 70/20/10, respectively.
电化学性能测试:如图5示，充放电电流为500mA/g。SiC电极半电池的首次可逆放 电比容量774mAh/g。Electrochemical performance test: As shown in Fig. 5, the charge and discharge current was 500 mA/g. First reversible SiC electrode half-cell The specific capacity is 774mAh/g.
通过对比实施例3和对比例2电化学性能测试结果，如图5所示，磷酸铁锂的引入可以提高SiC电极的放电比容量。By comparing the electrochemical performance test results of Example 3 and Comparative Example 2, as shown in FIG. 5, the introduction of lithium iron phosphate can increase the discharge specific capacity of the SiC electrode.
实施例4:Example 4:
将天然石墨粉末与LFP混合作为锂离子电池复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入PVDF的NMP分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过110℃真空干燥、滚压、剪裁制备成80G/10LFP复合电极片。其中，石墨、LFP、乙炔黑与聚偏氟乙酸(PVDF)的质量比分别为80/10/5/5。The natural graphite powder is mixed with LFP as a lithium ion battery composite anode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then a PVDF NMP dispersion is added to continue grinding into a uniform fluid slurry. The slurry was coated on a copper foil by a vacuum coater, and then dried, rolled, and cut at 110 ° C to prepare an 80 G/10 LFP composite electrode sheet. Among them, the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 80/10/5/5, respectively.
实施例5:Example 5:
将人工石墨粉末与LFP混合作为锂离子电池复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入PVDF的NMP分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过110℃真空干燥、滚压、剪裁制备成70G/20LFP复合电极片。其中，石墨、LFP、乙炔黑与聚偏氟乙酸(PVDF)的质量比分别为70/20/5/5。The artificial graphite powder and LFP are mixed as a lithium ion battery composite negative active material, acetylene black is added as a conductive agent, and fully ground in an agate mortar, and then the PVDF NMP dispersion is added to continue grinding into a uniform fluid slurry. The slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 110 ° C to prepare a 70 G/20 LFP composite electrode sheet. Among them, the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 70/20/5/5.
实施例6:Example 6
将人工石墨粉末与LFP混合作为锂离子电池的复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入PVDF的NMP分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过110℃真空干燥、滚压、剪裁制备成60G/30LFP复合电极片。其中，石墨、LFP、乙炔黑与聚偏氟乙酸(PVDF)的质量比分别为60/30/5/5。The artificial graphite powder is mixed with LFP as a composite negative active material of a lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then the NMP dispersion of PVDF is added to continue grinding into a uniform fluid slurry. The slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 110 ° C to prepare a 60 G/30 LFP composite electrode sheet. Among them, the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 60/30/5/5, respectively.
实施例7:Example 7
将人工石墨与LFP混合作为锂离子电池复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入PVDF的NMP分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过110℃真空干燥、滚压、剪裁制备成50G/40LFP复合电极片。其中，石墨、LFP、乙炔黑与聚偏氟乙酸(PVDF)的质量比分别为50/40/5/5。The artificial graphite and LFP are mixed as a composite active material of lithium ion battery composite, acetylene black is added as a conductive agent, and fully ground in an agate mortar, then the NMP dispersion of PVDF is added, and the slurry is continuously ground into a uniform fluid slurry, and vacuum is used. The coater coats the slurry on a copper foil, and then vacuum-dried, rolled, and cut at 110 ° C to prepare a 50 G/40 LFP composite electrode sheet. Among them, the mass ratio of graphite, LFP, acetylene black and polyvinylidene fluoride (PVDF) was 50/40/5/5, respectively.
对比例3:Comparative example 3:
将天然石墨粉末作为锂离子电池的复合负极活性材料,加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入PVDF的NMP分散体，继续研磨成均匀的流体浆料，用真 空涂布机将浆料涂布在铜箔上，然后经过110℃真空干燥、滚压、剪裁制备成90G电极片。其中，石墨、乙炔黑与聚偏氟乙酸(PVDF)的质量比分别为90/5/5。The natural graphite powder is used as a composite negative electrode active material of a lithium ion battery, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then the NMP dispersion of PVDF is added, and the slurry is continuously ground into a uniform fluid slurry. The empty coater coats the slurry on a copper foil, and then vacuum-dried, rolled, and cut at 110 ° C to prepare a 90 G electrode sheet. Among them, the mass ratio of graphite, acetylene black and polyvinylidene fluoride (PVDF) is 90/5/5.
电化学性能测试：实施例4～7与对比例3所制备的负极半电池的充放电电压为0.01～3V。首次充放电电压-容量曲线对比图如图6所示。纯石墨负极电池的首次放电比容量为431mAh/g。加入LFP以后，首次放电比容量增大，并且随着LFP比例的增加而增大。80G10LFP、70G20LFP、60G30LFP和50G40LFP的首次放电比容量依次为502，523，537，570mAh/g。Electrochemical performance test: The charge and discharge voltages of the negative electrode half-cells prepared in Examples 4 to 7 and Comparative Example 3 were 0.01 to 3 V. The comparison diagram of the first charge and discharge voltage-capacity curve is shown in Fig. 6. The first discharge specific capacity of the pure graphite negative electrode battery was 431 mAh/g. After the addition of LFP, the first discharge specific capacity increases and increases as the proportion of LFP increases. The first discharge specific capacities of the 80G10LFP, 70G20LFP, 60G30LFP and 50G40LFP were 502, 523, 537, 570 mAh/g.
实施例8:Example 8
称取LFP粉和乙炔黑粉末，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成纯LFP负极极片。其中，LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为70//20/10。Weigh LFP powder and acetylene black powder, fully grind it in an agate mortar, then add an aqueous dispersion of sodium carboxymethyl cellulose (CMC), continue grinding to a uniform fluid slurry, and use a vacuum coater to slurry The material was coated on a copper foil, and then vacuum dried, rolled, and cut at 60 ° C to prepare a pure LFP negative electrode tab. Among them, the mass ratio of LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 70//20/10, respectively.
电化学性能测试：如图7所示，充放电电压为0.01～1.5V，充放电电流为500mA/g，首次放电比容量为818mAh/g，充放电效率为29％。为了对比不同电压和电流下的充放电性能，如图8所示，充放电电压为0.01～3V，初始充放电电流为20mA/g，首次放电比容量为980mAh/g。当充放电电流增大为200mA/g，放电比容量稳定在300mAh/g。Electrochemical performance test: As shown in Fig. 7, the charge and discharge voltage was 0.01 to 1.5 V, the charge and discharge current was 500 mA/g, the first discharge specific capacity was 818 mAh/g, and the charge and discharge efficiency was 29%. In order to compare the charge and discharge performance under different voltages and currents, as shown in FIG. 8, the charge and discharge voltage is 0.01 to 3 V, the initial charge and discharge current is 20 mA/g, and the first discharge specific capacity is 980 mAh/g. When the charge and discharge current was increased to 200 mA/g, the discharge specific capacity was stabilized at 300 mAh/g.
对比例1、实施例1、实施例2和实施例8制备的负极半电池首次充放电的d Q/dV曲线对比图如图9所示，纯的LFP负极在0.5V左右有一个明显的还原峰，而纯的Si负极在0.5V左右没有还原峰。由于50Si20LFP和30Si40LFP负极都引入了LFP，其在0.5V左右处也都出现还原峰。Comparative Example 1, Example 1, Example 2 and Example 8 The comparison of the d Q/dV curves of the first charge and discharge of the negative half-cell was as shown in Fig. 9. The pure LFP negative electrode had an obvious reduction at about 0.5V. The peak, while the pure Si negative electrode has no reduction peak at around 0.5V. Since both the 50Si20LFP and the 30Si40LFP negative electrodes have introduced LFP, they also have reduction peaks at around 0.5V.
实施例9:Example 9
将氧化亚硅粉末与LFP粉末混合作为锂离子电池复合负极活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成50SiO/20LFP复合电极片。其中，氧化亚硅、LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为50/20/20/10。The SiO2 powder is mixed with the LFP powder as a lithium ion battery composite anode active material, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added. The slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 SiO/20 LFP composite electrode sheet. Among them, the mass ratio of SiO2, LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 50/20/20/10, respectively.
实施例10:Example 10:
将氧化亚硅粉末与LFP粉末混合作为锂离子电池的复合负极活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、 滚压、剪裁制备成30SiO/40LFP复合电极片。其中，氧化亚硅、LFP、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为30/40/20/10。The siloxane powder is mixed with the LFP powder as a composite anode active material of a lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) is added. Continue grinding to a uniform fluid slurry, apply the slurry to a copper foil with a vacuum coater, and then vacuum dry at 60 ° C. Rolling and cutting were prepared into a 30 SiO/40 LFP composite electrode sheet. Among them, the mass ratio of SiO2, LFP, acetylene black and sodium carboxymethylcellulose (CMC) was 30/40/20/10, respectively.
对比例4:Comparative example 4:
称取氧化亚硅粉末和乙炔黑粉末，在玛瑙研钵中充分研磨均匀，然后加入羧甲基纤维素钠(CMC)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成纯SiO负极极片。其中，氧化亚硅、乙炔黑与羧甲基纤维素钠(CMC)的质量比分别为70//20/10。The SiO2 powder and the acetylene black powder were weighed, thoroughly ground in an agate mortar, and then an aqueous dispersion of sodium carboxymethylcellulose (CMC) was added to continue grinding to a uniform fluid slurry using a vacuum coater. The slurry was coated on a copper foil, and then vacuum dried, rolled, and cut at 60 ° C to prepare a pure SiO negative electrode tab. Among them, the mass ratio of silicon oxypropylene, acetylene black and sodium carboxymethyl cellulose (CMC) was 70//20/10, respectively.
电化学性能测试：如图10所示，充放电电压为0.01～3V，充放电电流为200mA/g。由图10可知，加入LFP以后，负极半电池的放电比容量降低，这是由于氧化亚硅相比LFP有更高的理论容量。对比例4、实施例9和实施例10所制备负极半电池的首次充放电效率分别为54％，52.9％和50％，虽然加入LFP后首次放电比容量和充放电效率均有所降低，但是长期循环性能有望提高。Electrochemical performance test: As shown in Fig. 10, the charge and discharge voltage was 0.01 to 3 V, and the charge and discharge current was 200 mA/g. As can be seen from Fig. 10, after the addition of LFP, the discharge specific capacity of the negative half-cell is lowered because the oxidized silicon has a higher theoretical capacity than the LFP. The first charge and discharge efficiencies of the negative electrode half-cells prepared in Comparative Example 4, Example 9 and Example 10 were 54%, 52.9% and 50%, respectively, although the first discharge specific capacity and charge-discharge efficiency were reduced after the addition of LFP, Long-term cycle performance is expected to increase.
实施例11:Example 11
将纳米硅粉(非晶硅)和LFP粉末混合作为锂离子电池的复合负极的活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入海藻酸钠的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成50Si/20LFP复合电极片。其中，纳米硅粉、LFP、乙炔黑与海藻酸钠的质量比分别为50/20/20/10。The nano silicon powder (amorphous silicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, fully ground in an agate mortar, and then an aqueous dispersion of sodium alginate is added. The slurry was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 50 Si/20 LFP composite electrode sheet. Among them, the mass ratio of nano silicon powder, LFP, acetylene black and sodium alginate is 50/20/20/10, respectively.
SEM形貌分析：将充放电电压为0.01～1.5V，充放电电流为200mA/g循环100周后的电池拆开，分析形貌特征。操作步骤为：在手套箱中将电池拆开，与组装电池的步骤相反。取出负极极片，用二甲基碳酸酯(DMC)将极片冲洗干净，并真空干燥待测。用冷场发射电子扫描显微镜(日立S4800)测试形貌特征。如图11所示。循环后的50Si/20LFP复合电极极片表面有比较致密的膜，没有出现明显的裂纹。SEM topography analysis: The battery was disassembled after the charge-discharge voltage was 0.01-1.5 V, and the charge-discharge current was 200 mA/g for 100 weeks, and the morphology was analyzed. The procedure is as follows: Disassemble the battery in the glove box, as opposed to the procedure for assembling the battery. The negative electrode tab was taken out, the pole piece was rinsed off with dimethyl carbonate (DMC), and vacuum dried for testing. The topographical features were tested using a cold field emission electron scanning microscope (Hitachi S4800). As shown in Figure 11. The surface of the 50Si/20LFP composite electrode after the cycle has a relatively dense film, and no obvious cracks appear.
对比例5:Comparative example 5:
将纳米硅粉(非晶硅)作为锂离子电池的复合负极的活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入海藻酸钠的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成Si复合电极片。其中，纳米硅粉、乙炔黑与海藻酸钠的质量比分别为70/20/10。The nano silicon powder (amorphous silicon) is used as an active material of the composite negative electrode of a lithium ion battery, and acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then an aqueous dispersion of sodium alginate is added to continue grinding to uniformity. The fluid slurry was coated on a copper foil with a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a Si composite electrode sheet. Among them, the mass ratio of nano silicon powder, acetylene black and sodium alginate is 70/20/10 respectively.
SEM形貌分析：用与实施例11相同的步骤测试100周循环后的负极极片形貌特征。如 图12所示。循环后的Si极片表面有很明显的裂纹，这是由于充放电过程中硅的体积膨胀所致，这些裂纹严重影响了硅负极的循环性能。对比图11和图12可以得出，LFP的加入有效的抑制了硅负极的体积膨胀，有利于保护硅表面膜的稳定，从而提高电极电化学性能。SEM topography analysis: The morphology of the negative electrode tab after the 100-week cycle was tested in the same manner as in Example 11. Such as Figure 12 shows. There are obvious cracks on the surface of the Si pole piece after the cycle, which is caused by the volume expansion of silicon during charge and discharge. These cracks seriously affect the cycle performance of the silicon negative electrode. Comparing Fig. 11 and Fig. 12, it can be concluded that the addition of LFP effectively suppresses the volume expansion of the silicon negative electrode, and is beneficial for protecting the stability of the silicon surface film, thereby improving the electrochemical performance of the electrode.
实施例12:Example 12
将纳米硅粉(非晶硅)和LFP粉末混合作为锂离子电池的复合负极的活性材料，加入super P和PEDOT-PSS作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入聚丙烯酸(PAA)的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成20Si/70LFP复合电极片。其中，纳米硅粉、LFP、super P和PEDOT-PSS与聚丙烯酸的质量比分别为20/70/3/2/5。Mixing nano-silica powder (amorphous silicon) and LFP powder as active materials of composite negative electrode of lithium ion battery, adding super P and PEDOT-PSS as conductive agent, fully grinding in an agate mortar, and then adding polyacrylic acid (PAA) The aqueous dispersion was continuously ground into a uniform fluid slurry, and the slurry was coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 20Si/70LFP composite electrode sheet. Among them, the mass ratio of nano silicon powder, LFP, super P and PEDOT-PSS to polyacrylic acid was 20/70/3/2/5, respectively.
电化学性能测试：所制备电极的第1到3圈循环伏安测试结果如图13所示。扫描速率为100uV/s。第1圈，2个明显的氧化峰分别出现在0.3V和0.5V左右，还原峰在0.2V。第2，3圈只有1个明显的氧化峰在0.4V左右，还原峰左移。Electrochemical performance test: The results of the first to third cycles of cyclic voltammetry of the prepared electrode are shown in FIG. The scan rate is 100 uV/s. On the first lap, two distinct oxidation peaks appeared at around 0.3V and 0.5V, respectively, and the reduction peak was at 0.2V. On the 2nd and 3rd laps, only one obvious oxidation peak was around 0.4V, and the reduction peak shifted to the left.
实施例13:Example 13
将纳米硅粉(非晶硅)和LFP粉末混合作为锂离子电池的复合负极的活性材料，加入乙炔黑作为导电剂，在玛瑙研钵中充分研磨均匀，然后加入丁苯橡胶/羧甲基纤维素钠的水分散体，继续研磨成均匀的流体浆料，用真空涂布机将浆料涂布在铜箔上，然后经过60℃真空干燥、滚压、剪裁制备成60Si/10LFP复合电极片。其中，纳米硅粉、LFP、乙炔黑与丁苯橡胶/羧甲基纤维素钠的质量比分别为60/10/20/10。The nano silicon powder (amorphous silicon) and the LFP powder are mixed as an active material of the composite negative electrode of the lithium ion battery, acetylene black is added as a conductive agent, and is uniformly ground in an agate mortar, and then styrene-butadiene rubber/carboxymethyl fiber is added. The aqueous dispersion of sodium is continuously ground into a uniform fluid slurry, and the slurry is coated on a copper foil by a vacuum coater, and then vacuum dried, rolled, and cut at 60 ° C to prepare a 60Si/10LFP composite electrode sheet. . Among them, the mass ratio of nano silicon powder, LFP, acetylene black and styrene butadiene rubber/carboxymethyl cellulose sodium is 60/10/20/10, respectively.
电化学性能测试:如图14示，60Si/10LFP复合电极半电池的首次可逆放电比容量3456mAh/g，首次充放电效率69.9％。 Electrochemical performance test: As shown in Fig. 14, the first reversible discharge specific capacity of the 60Si/10LFP composite electrode half-cell was 3456 mAh/g, and the first charge-discharge efficiency was 69.9%.

Claims (10)

  1. 一种锂离子电池的复合负极活性材料，其特征在于，所述复合负极的活性材料含有磷酸铁锂与常规负极材料，所述常规负极材料选自碳基粉末、含硅粉末中的任一种或其结合。A composite anode active material for a lithium ion battery, characterized in that the active material of the composite anode contains lithium iron phosphate and a conventional anode material, and the conventional anode material is selected from any one of a carbon-based powder and a silicon-containing powder. Or a combination thereof.
  2. 根据权利要求1所述的复合负极活性材料，其特征在于，所述磷酸铁锂占复合负极活性材料总量的0～100wt％，但不包括0wt％。The composite anode active material according to claim 1, wherein the lithium iron phosphate accounts for 0 to 100% by weight of the total amount of the composite anode active material, but does not include 0% by weight.
  3. 根据权利要求1所述的复合负极活性材料，其特征在于，所述碳基粉末选自人工石墨、天然石墨、中间相碳微球、石油焦、碳纤维、热解树脂碳粉末中的一种或几种的任意组合；所述含硅粉末选自非晶硅、多晶硅、氧化亚硅、硅基合金、硅碳复合结构粉末中的一种或几种的任意组合。The composite anode active material according to claim 1, wherein the carbon-based powder is one selected from the group consisting of artificial graphite, natural graphite, mesocarbon microbeads, petroleum coke, carbon fiber, and pyrolyzed carbon powder. Or any combination of several; the silicon-containing powder is selected from any one or a combination of amorphous silicon, polycrystalline silicon, oxysulfide, silicon-based alloy, silicon-carbon composite structural powder.
  4. 根据权利要求3所述的复合负极活性材料，其特征在于，所述非晶硅、多晶硅为纳米级或微米级颗粒状；所述氧化亚硅为微米级颗粒状；所述硅基合金粉末为微米级硅镍合金；所述硅碳复合结构粉末为碳包覆纳米硅颗粒结构粉末。The composite anode active material according to claim 3, wherein the amorphous silicon and the polycrystalline silicon are in the form of nanometer or micron-sized particles; the silicon oxide oxide is in the form of micron-sized particles; and the silicon-based alloy powder is a micron-sized silicon-nickel alloy; the silicon-carbon composite structural powder is a carbon-coated nano-silicon particle structured powder.
  5. 一种锂离子电池的复合负极片，其特征在于包含权利要求1-4中任一权利要求所述的复合负极活性材料，还包括导电剂和粘结剂。A composite negative electrode sheet of a lithium ion battery, characterized by comprising the composite negative electrode active material according to any one of claims 1 to 4, further comprising a conductive agent and a binder.
  6. 根据权利要求5所述的复合负极片，其特征在于，所述导电剂选自乙炔黑、Super P和PEDOT-PSS中的一种或任意几种以任意比例混合，占负极总量的5～20wt％；所述的粘结剂为油性粘结剂或者水系粘结剂或增稠剂，占负极总量的5～10wt％。The composite negative electrode sheet according to claim 5, wherein the conductive agent is selected from one or any of acetylene black, Super P and PEDOT-PSS mixed in any ratio, and accounts for 5 to 5 of the total amount of the negative electrode. 20wt%; the binder is an oily binder or a water-based binder or a thickener, accounting for 5 to 10% by weight of the total amount of the anode.
  7. 根据权利要求5所述的复合负极片，其特征在于，所述油性粘结剂为聚偏二氟乙烯，所述水系粘结剂选自聚丙烯酸、聚丙烯酸钠、丁苯橡胶、海藻酸、海藻酸钠中的一种或任意几种以任意比例混合而成，所述增稠剂选自羧甲基纤维素或者羧甲基纤维素钠中的一种。The composite negative electrode sheet according to claim 5, wherein the oily binder is polyvinylidene fluoride, and the aqueous binder is selected from the group consisting of polyacrylic acid, sodium polyacrylate, styrene butadiene rubber, alginic acid, One or any of several sodium alginate is mixed in an arbitrary ratio, and the thickener is selected from one of carboxymethylcellulose or sodium carboxymethylcellulose.
  8. 根据权利要求5所述的复合负极片，其特征在于，所述复合负极的活性材料占负极总量的70～90wt％。The composite negative electrode sheet according to claim 5, wherein the active material of the composite negative electrode accounts for 70 to 90% by weight of the total amount of the negative electrode.
  9. 一种权利要求5所述的复合负极片的制备方法，其特征在于，该方法包括以下步骤：将磷酸铁锂粉末与常规负极材料混合为锂离子电池的复合负极活性材料；加入导电剂、粘结剂分散体，经过研磨或者高速机械搅拌制备出均匀的流体浆料；将得到的流体浆料经过涂布、烘干、碾压之后，得到锂离子电池负极极片。A method for preparing a composite negative electrode sheet according to claim 5, characterized in that the method comprises the steps of: mixing lithium iron phosphate powder with a conventional negative electrode material into a composite negative active material of a lithium ion battery; adding a conductive agent, sticking The mixture dispersion is prepared by grinding or high-speed mechanical stirring to prepare a uniform fluid slurry; after the obtained fluid slurry is coated, dried and rolled, a negative electrode sheet of the lithium ion battery is obtained.
  10. 一种锂离子电池，其特征在于，含有权利要求5-7中任一权利要求所述的复合负极片。 A lithium ion battery comprising the composite negative electrode sheet according to any one of claims 5-7.
PCT/CN2017/109003 2017-09-27 2017-11-01 Lithium iron phosphate-containing composite negative electrode active material of lithium ion battery, composite negative electrode plate, and lithium ion battery WO2019061674A1 (en)

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