WO2024099106A1 - 补锂材料及其制备方法和应用 - Google Patents

补锂材料及其制备方法和应用 Download PDF

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WO2024099106A1
WO2024099106A1 PCT/CN2023/127143 CN2023127143W WO2024099106A1 WO 2024099106 A1 WO2024099106 A1 WO 2024099106A1 CN 2023127143 W CN2023127143 W CN 2023127143W WO 2024099106 A1 WO2024099106 A1 WO 2024099106A1
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Prior art keywords
lithium
supplement material
lithium supplement
coating layer
supplementing
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PCT/CN2023/127143
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English (en)
French (fr)
Inventor
裴现一男
万远鑫
孔令涌
赖佳宇
陈心怡
张莉
钟文
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深圳市德方创域新能源科技有限公司
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Publication of WO2024099106A1 publication Critical patent/WO2024099106A1/zh

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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of battery technology, and in particular to a lithium supplement material and a preparation method and application thereof.
  • the positive electrode lithium supplement additive is used as a supplementary material for lithium ions, and lithium is added to the inside of the battery to supplement lithium ions before the lithium-ion battery works.
  • part of the lithium of the positive electrode lithium supplement additive will not be released during actual use, and it basically does not participate in the lithium supplement process, resulting in a waste of lithium elements, which is not conducive to the promotion and application of the positive electrode lithium supplement additive.
  • the present application provides a lithium supplement material and a preparation method and application thereof to solve the problem of waste of lithium elements.
  • the present application provides a lithium-supplementing material, the chemical formula of which is Li x-na A a M y O z , wherein A is selected from other metal elements except Li, M is selected from at least one transition metal element, and 1 ⁇ x ⁇ 8, y>0, 0 ⁇ z ⁇ 6, 1 ⁇ n ⁇ 4, 0 ⁇ a ⁇ 2.
  • the lithium atoms that cannot participate in the lithium replenishment process are replaced with other metals.
  • Li x-na A a My O z can achieve the same lithium replenishment effect as Li x My O z .
  • the product is a compound with less lithium content or no lithium, which will not cause a large waste of lithium.
  • the lithium replenishment material provided by the present application can greatly reduce the cost of the lithium replenishment material without losing the lithium replenishment effect, form a cost-effective lithium replenishment material, lower the price threshold of the lithium replenishment material, help promote the positive electrode lithium replenishment additive, and promote the development and progress of the new energy industry.
  • the atomic radius of A can be greater than the atomic radius of Li, and the lithium atoms with smaller volume that cannot participate in the lithium replenishment process can be replaced with A atoms with larger volume.
  • the large atomic radius of A makes it easier for lithium to escape for lithium replenishment.
  • A is selected from at least one of Na and K elements, and the chemical formula of the lithium supplement material is Li xa A a My O z .
  • the lithium atoms that cannot participate in the lithium replenishment process can be replaced by cheaper alkali metals such as Na and/or K.
  • Li xa A a My O z can achieve the same zThe same lithium supplement effect, in the lithium supplement material, Na, K and Li are all positive monovalent, have the same valence state, Na, K and Li have similar properties, when Na and/or K replace Li, the change in the properties of the lithium supplement material is not significant, at least 4 lithium ions in the lithium supplement material can be used to supplement the battery system, at the same time, after the lithium supplement material is supplemented with lithium, the product is a sodium or potassium compound with less lithium content or no lithium, compared with Li, the price of Na and K is lower, even if it is only used as a structural support, it will not cause a large waste, the lithium supplement material provided by the present application can significantly reduce the cost of the lithium supplement material without losing the lithium supplement effect, form a cost-effective lithium supplement material, reduce the price threshold of the lithium
  • the chemical formula of the lithium supplement material is Li 5-a A a MO 4 , where a ⁇ 1, and M is selected from at least one of Fe, Co, Ni, Mn, Al, Cr, Ga, In, La, and Bi.
  • the crystal structure of the lithium supplementing material is the same as the crystal structure of Li 5 MO 4 .
  • the intrinsic density of the lithium supplementing material is 2-3.5 g/cm 3 .
  • the band gap of the lithium supplementing material is 1-4 eV.
  • the unit cell volume of the lithium supplementing material is
  • the unit cell of the lithium replenishing material consists of 40 atoms.
  • the chemical formula of the lithium supplement material is Li 4 AMO 4
  • the particle size of the lithium supplement material is 0.1-100 microns.
  • the minimum separation voltage of the lithium-supplementing material is lower than the minimum separation voltage of Li 5 MO 4 , and the minimum separation voltage of the lithium-supplementing material refers to the minimum voltage at which four lithium ions are released from the lithium-supplementing material, and the minimum separation voltage of Li 5 MO 4 refers to the minimum voltage at which four lithium ions are released from Li 5 MO 4 .
  • the present application provides a method for preparing a lithium supplement material, the method for preparing a lithium supplement material comprising:
  • the solid I In an inert gas atmosphere, the solid I is heated to 800-900° C. for 12-36 hours. After the heating is completed, the solid is cooled to obtain Li x-na A a My O z .
  • A is selected from sodium or potassium
  • the metal source A is at least one of a sodium source and a potassium source
  • the method for preparing the lithium supplement material comprises:
  • the solid I In an inert gas atmosphere, the solid I is heated to 800-900° C. for 12-36 hours. After the heating is completed, the solid is cooled to obtain Li xa A a FeO 4 .
  • the iron source includes one or a combination of at least two of ferric sulfate, ferric nitrate, ferric chloride, ferric citrate, ferric hydroxide, and ferric oxide.
  • the sodium source includes one or a combination of at least two of sodium chloride, sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium sulfate, sodium nitrate, and sodium oxide.
  • the potassium source includes one or a combination of at least two of potassium chloride, potassium carbonate, potassium hydroxide, potassium bicarbonate, potassium sulfate, potassium nitrate, and potassium oxide.
  • the lithium source includes one or a combination of at least two of lithium hydroxide, lithium oxide, lithium chloride, lithium nitrite, lithium nitrate, lithium oxalate, lithium carbonate and lithium acetate.
  • the heating rate of heating the solid I is 1-10°C/min.
  • the present application provides a positive electrode sheet, the positive electrode sheet comprising the lithium-supplementing material as described in any one of the above items or the positive electrode sheet comprising the lithium-supplementing material prepared by the preparation method of the lithium-supplementing material as described in any one of the above items.
  • the present application provides a battery, characterized in that the battery includes the positive electrode sheet as described above, or the battery includes the lithium-supplementing material as described above, or the battery includes the lithium-supplementing material prepared by the preparation method of the lithium-supplementing material as described above.
  • Li x-na A a My O z has a good lithium replenishment effect, and at the same time, the lithium utilization rate of the lithium replenishment material is high.
  • the lithium replenishment material is replenished with lithium, the lithium content in the product is less or does not contain lithium, the waste of lithium is reduced, and the cost of the lithium replenishment material is greatly reduced; on the other hand, during the use of the lithium replenishment material, the metal element with a large atomic radius makes it easier for lithium to be released for lithium replenishment.
  • FIG. 1 is an XRD diffraction spectrum of a lithium supplement material and Li 5 FeO 4 provided in one embodiment of the present application.
  • FIG. 2 is a SEM image of the Li 4.5 Na 0.5 FeO 4 material provided in the first embodiment of the present application.
  • FIG3 is a charging curve diagram of the lithium ion batteries provided in Examples 1-3 and Comparative Example 1.
  • FIG. 4 is a full battery charging curve diagram provided in the first embodiment of the present application.
  • SEI film refers to Solid Electrolyte Interphase, that is, solid electrolyte interface membrane.
  • SP Super P, conductive carbon black, a conductive agent.
  • PVDF poly(vinylidene fluoride), polyvinylidene fluoride, a kind of adhesive.
  • NMP 1-Methyl-2-pyrrolidinone, N-methylpyrrolidone, a solvent.
  • a large amount of solid electrolyte interface film (SEI film) will be produced on the surface of the negative electrode of the battery, which consumes the limited lithium ions and electrolyte in the battery, causing irreversible capacity loss, reducing the energy density of the lithium-ion secondary battery and reducing the charge and discharge efficiency of the electrode material.
  • SEI film solid electrolyte interface film
  • the positive electrode lithium supplement additive is used as a supplementary material for lithium ions, and lithium is added to the battery to supplement lithium ions before the lithium-ion battery works.
  • the demand for lithium sources is large and the cost is high, which increases the price threshold of the positive electrode lithium supplement additive; on the other hand, part of the lithium of the positive electrode lithium supplement additive will not be detached during actual use, and basically does not participate in the lithium supplement process, resulting in a waste of lithium elements, which is not conducive to the promotion and application of the positive electrode lithium supplement additive.
  • the present application provides a lithium supplement material, which is applied to the positive electrode of the battery to pre-lithiate the positive electrode, and to add lithium to the inside of the battery to supplement lithium ions before the battery is operated.
  • the lithium supplement material when the lithium supplement material is applied, can be coated on the outer surface of the positive electrode of the battery, or the lithium supplement material can be embedded in the outer surface of the positive electrode of the battery.
  • the lithium supplement material can also be added during the preparation process of the positive electrode of the battery, so that the lithium supplement material is dispersed on the outer surface and inside of the positive electrode of the battery.
  • the lithium supplement material has a high lithium content.
  • the lithium (Li) of the lithium supplement material can be released and migrate to the negative electrode of the battery, offsetting the irreversible lithium loss caused by the formation of the SEI film, so as to increase the total capacity and energy density of the battery.
  • the chemical formula of the lithium supplement material is Li x-na A a My O z , wherein A is selected from other metal elements except Li, M is selected from at least one transition metal element, and 1 ⁇ x ⁇ 8, y>0, 0 ⁇ z ⁇ 6, 1 ⁇ n ⁇ 4, 0 ⁇ a ⁇ 2.
  • n is the valence state of element A in Li x-na A a My O z .
  • the chemical formula of lithium supplement materials in the prior art is usually Li x My O z .
  • Li x My O z Only part of the lithium will be released to form active lithium ions to replenish the battery system, and the remaining lithium is used as a material structure support, which basically does not participate in the lithium replenishment process, and the utilization rate of lithium is low.
  • other metal elements are doped at the Li position.
  • Li x-na A a My O z can achieve the same lithium replenishment effect as Li x My O z ;
  • a uses a metal element with a lower price after the lithium replenishment material is replenished with lithium, the product does not contain lithium or contains less lithium, which greatly reduces the cost of the lithium replenishment material, forms a cost-effective lithium replenishment material, reduces the price threshold of the lithium replenishment material, and helps to promote the positive electrode lithium replenishment additive, while promoting the development and progress of the new energy industry;
  • a uses a metal element with a larger volume than lithium in the preparation process of the lithium replenishment material, it is more conducive to lithium entering the reaction system to form a Li x-na A a My O z structure.
  • the large atomic radius of A makes it easier for lithium to be released for lithium replenishment.
  • A is selected from at least one of Na and K, and the chemical formula of the lithium supplement material is Li xa A a My O z .
  • the chemical formula of the lithium-replenishing material is Li xa Na a My O z
  • the chemical formula of the lithium-replenishing material is Li xa Ka My O z
  • the chemical formula of the lithium supplement material may be Li 5-a A a FeO 4 , Li 6-a A a MnO 4 , Li 6-a A a CoO 4 , Li 6-a A a ZnO 4 , or the like.
  • the chemical formula of lithium supplement materials in the prior art is usually Li x M y O z .
  • the lithium supplement materials in the prior art do not contain Na and K atoms. During the use of lithium supplement materials, only part of the lithium will be released to form active lithium ions to supplement the battery system. The remaining lithium is used as a material structure support and basically does not participate in the lithium supplement process. The lithium utilization rate is low. For example, in the lithium supplement material Li 5 FeO 4 , each molecule can release four lithium ions during the lithium supplement process. The equation is as follows:
  • Li 5 FeO 4 Only four lithium ions in each Li 5 FeO 4 molecule can be utilized, and the remaining lithium does not participate in the lithium replenishment process. That is, when Li 5 FeO 4 is used as a lithium replenishment material, only about 80% of the lithium will be released to form active lithium ions to replenish the battery system, and the remaining 20% or so of lithium serves as material structure support and basically does not participate in the lithium replenishment process, resulting in lithium waste.
  • Li xa A a My O z can achieve the same lithium replenishment effect as Li x My O z .
  • Na, K and Li are all positive monovalent and have the same valence state. Na, K and Li have similar properties.
  • the properties of the lithium replenishment material are not greatly changed.
  • the chemical formula of the lithium replenishment material is Li 4 NaFeO 4
  • each molecule can also release four lithium ions during the lithium replenishment process. The equation is as follows:
  • the lithium replenishing material can significantly reduce the cost of the lithium replenishing material without losing the lithium replenishing effect, forming a cost-effective lithium replenishing material, lowering the price threshold of the lithium replenishing material, and contributing to the promotion of positive electrode lithium replenishing additives, while promoting the development and progress of the new energy industry;
  • the atomic radius of Na and K is larger than that of Li, the smaller lithium atoms that cannot participate in the lithium replenishment process are replaced by larger Na and/or K atoms.
  • the large atomic radius of Na and K makes it easier for lithium to be released for lithium replenishment.
  • the release and non-release of lithium in this application are based on the charge and discharge voltage of the battery.
  • the charge and discharge voltage of a battery containing Li 5 FeO 4 lithium supplement material is generally 4.3V.
  • the charge and discharge voltage of a battery containing Li 5 FeO 4 lithium supplement material is generally 4.3V.
  • the charge and discharge voltage of a battery containing Li 5 FeO 4 lithium supplement material is generally 4.3V.
  • the voltage above 5V is not the charge and discharge voltage of the battery under normal circumstances.
  • This application only considers the lithium ion voltage under the charge and discharge voltage of the normal battery. The child's escape situation.
  • the increase in the content of Na and K in the lithium supplement material means that the mass of the lithium supplement material will increase.
  • the content of Na and K can be selectively applied according to actual needs to balance the price and quality of the lithium supplement material. That is, when the lithium supplement material is applied to products where quality does not need to be considered, the content of Na and K can be relatively increased. For application scenarios where the product needs to be miniaturized or reduced in weight, the content of Na and K can be reduced in the design.
  • A may be selected from but is not limited to at least one of Na, K, Al, and Fe, and the chemical formula of the lithium supplement material may be Li 5-3a Al a FeO 4 , Li 5-3a Al a Fe b1 Al b2 O 4 , Li 6-3a Al a MnO 4 , Li 6-3a Al a CoO 4 , Li 6-3a Al a ZnO 4 , Li 5-na Al a1 Na a2 FeO 4 , Li 6-na Al a1 Na a2 MnO 4 , Li 6-na Al a1 Na a2 CoO 4 , Li 6-na Al a1 Na a2 ZnO 4 , Li 5-na Al a1 Na a2 Fe b1 Al b2 O 4 , Li 5-na Al a1 K a2 FeO 4 , Li 5-na Al a1 K a2 Fe b1 Al b2 O 4 , Li 6-na Al a1 K a2 FeO 4
  • a1+a2 a
  • n is the average valence state
  • b1+b2 1; for example, Li 6-na Al a1 Na a2 MnO 4
  • n is the average valence state of a1 Al and a2 Na.
  • the chemical formula of the lithium supplement material is Li 5-a A a MO 4 , and a ⁇ 1, A is selected from at least one of Na and K, and M is selected from at least one of Fe, Co, Ni, Mn, Al, Cr, Ga, In, La, and Bi.
  • A is selected from at least one of Na and K
  • M is selected from at least one of Fe, Co, Ni, Mn, Al, Cr, Ga, In, La, and Bi.
  • Li 5 MO 4 only one lithium cannot be removed, that is, only one lithium cannot participate in the lithium supplement process.
  • at least part of the lithium that cannot be removed in Li 5 MO 4 is replaced with Na and/or K atoms, and the prepared Li 5-a A a MO 4 lithium supplement material can have a good lithium supplement effect.
  • the cost of the lithium supplement material is greatly reduced.
  • the lithium in the lithium supplement material is more easily removed for lithium supplementation.
  • a can be 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.05.
  • the chemical formula of the lithium supplement material may be Li 4 NaFeO 4 , Li 4 KFeO 4 , Li 4 NaNiO 4 , Li 4 KMnO 4 , Li 4.5 Na 0.5 FeO 4 , Li 4.5 K 0.5 CoO 4 , Li 4 Na 0.5 K 0.5 NiO 4 , Li 4 Na 0.5 K 0.5 FeO 4 , Li 4 Na 0.8 K 0.2 FeO 4 , Li 4.2 Na 0.5 K 0.3 FeO 4 , Li 4.4 K 0.6 CrO 4 , Li 4.6 Na 0.4 AlO 4 , Li 4.8 Na 0.2 CrO 4 .
  • the intrinsic density of the lithium supplement material is 2-3.5 g/cm 3 .
  • the intrinsic density of the lithium supplement material is equal to the mass of the lithium supplement material divided by the volume of the lithium supplement material after removing the pores, that is, the compacted density of the lithium supplement material.
  • the intrinsic density of the lithium supplement material is set to 2-3.5 g/cm 3 , so that the unit volume of the lithium supplement material contains more lithium that can be used to supplement lithium ions to the battery. At the same time, the lithium in the lithium supplement material is easier to be extracted for lithium supplementation.
  • the intrinsic density of the lithium supplementing material is 2-3 g/cm 3 .
  • the intrinsic density of the lithium supplementing material is 2.5-3.5 g/cm 3 .
  • the intrinsic density of the lithium supplementing material may be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4 or 3.5 g/cm 3 .
  • the bandgap width of the lithium supplement material is 1-4 eV.
  • the bandgap width refers to a band gap width, that is, the minimum energy for valence electrons in the lithium supplement material to transition from the valence band to the conduction band.
  • the bandgap width of the lithium supplement material is set to 1-4 eV, so that the lithium supplement material has higher conductivity and lithium ion diffusion coefficient.
  • the band gap of the lithium supplementing material is 1-2 eV.
  • the band gap of the lithium supplementing material is 2-3 eV.
  • the band gap of the lithium supplementing material is 3-4 eV.
  • the band gap of the lithium supplementing material is 1-3 eV.
  • the band gap of the lithium supplementing material is 2-4 eV.
  • the bandgap of the lithium supplementing material may be 2, 2.5, 3, 3.5, or 4 eV.
  • the unit cell volume of the lithium supplementing material is The unit cell is the most basic geometric unit constituting a crystal. In this embodiment, the unit cell of the lithium supplementing material is composed of 40 atoms.
  • the unit cell volume of the lithium supplementing material is
  • the unit cell volume of the lithium supplementing material is
  • the unit cell volume of the lithium supplement material is 300, 350, 400, 450 or
  • FIG. 1 is an XRD diffraction spectrum of a lithium supplement material and Li 5 FeO 4 provided in one embodiment of the present application.
  • the crystal structure of the lithium supplement material is the same as the crystal structure of Li 5 MO 4.
  • the crystal structure of Li 5 MO 4 is an anti-fluorite structure, belonging to the orthorhombic system and the Pbca space point group.
  • the lithium supplement material Li 5-a A a MO 4 in the present application has the same crystal structure as Li 5 MO 4 , that is, the lithium supplement material Li 5-a A a MO 4 also has an anti-fluorite structure, and the Li 5-a A a MO 4 crystal belongs to the orthorhombic system and the Pbca space point group.
  • Li 5 FeO 4 As an example, it can be seen from Figure 1 that the characteristic peaks of the lithium-replenishing material in the present application overlap highly with those of Li 5 FeO 4 , and the lithium-replenishing material in the present application has the same crystal structure as Li 5 FeO 4 , indicating that after replacing at least part of the lithium that cannot be removed from Li 5 FeO 4 with Na and/or K atoms, the prepared Li 5-a A a FeO 4 lithium-replenishing material does not change the atomic connection relationship and structure in Li 5 FeO 4 , and the Li 5-a A a FeO 4 lithium-replenishing material still has a similar lithium-replenishing effect as Li 5 FeO 4 after losing part of the lithium.
  • the chemical formula of the lithium supplement material is Li 4 AMO 4
  • the particle size of the lithium supplement material is 0.1-100 micrometers.
  • the particle size of the lithium supplement material is 0.1-100 microns, which can refer to the average particle size of all particles in the lithium supplement material being within the range of 0.1-100 microns, or the maximum particle size of all particles in the lithium supplement material being 100 microns and the minimum particle size being 0.1 microns.
  • the particle size of the lithium supplement material is controlled between 0.1 microns and 100 microns, which can ensure the rapid escape of lithium ions while improving the dispersibility of the lithium supplement material, facilitating the use of the lithium supplement material and protecting the electrode.
  • the particle size of the lithium supplement material may be 0.1-10 microns, 0.1-50 microns, 1-20 microns, 10-25 microns, 10-80 microns, 20-90 microns, 30-50 microns, 40-60 microns, 50-75 microns, 60-100 microns, 70-100 microns, 0.5-5 microns or 5-25 microns.
  • the particle size of the lithium supplementing material may be 0.1, 0.5, 1, 5, 10, 15, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90 or 100 microns.
  • the minimum separation voltage of the lithium supplement material is lower than the minimum separation voltage of Li 5 MO 4.
  • the minimum separation voltage of the lithium supplement material refers to the minimum voltage for four lithium ions to be separated from the lithium supplement material.
  • the minimum separation voltage of Li 5 MO 4 refers to the minimum voltage for four lithium ions to be separated from Li 5 MO 4.
  • the ionic radius of the lithium that cannot be separated is relatively small, it is difficult for the remaining four lithiums to be separated.
  • the ionic radius of Na and K is larger than the ionic radius of Li, the lithium atoms with smaller volume that cannot participate in the lithium supplement process are replaced with Na and/or K atoms with larger volume.
  • the minimum separation voltage of the lithium supplement material provided by the present application is lower than the minimum separation voltage of Li 5 MO 4 .
  • the outer surface of the lithium supplement material is coated with a first coating layer, and the first coating layer is used to isolate the lithium supplement material from moisture and carbon dioxide.
  • the first coating layer can protect the lithium supplement material and improve the stability of the lithium supplement material to ensure the lithium supplement effect of the lithium supplement material. At the same time, it ensures the stability and uniformity of the lithium supplement of the lithium supplement material in the electrode active slurry and active layer, as well as good processing performance.
  • the first coating layer can be located on the outer surface of part of the lithium supplement material, and also The entire outer surface of the lithium-supplementing material may be coated, and this application does not impose any limitation on this.
  • the first coating layer material includes at least one of ceramic, polymer or carbon material.
  • the ceramic includes at least one of Al 2 O 3 , SiO 2 , boehmite, Si 3 N 4 , SiC and BN;
  • the polymer includes one or more of polyvinylidene fluoride, sodium alginate, sodium carboxymethyl cellulose, polyacrylic acid, polyacrylic acid salt, polyacrylonitrile, polyamide, polyimide, polyvinyl pyrrolidone, polyethylene oxide (PEO), polypyrrole (PPy), polytetrafluoroethylene (PTFE), polyurethane (PU), sodium carboxymethyl cellulose and polyacrylic acid;
  • the carbon material includes at least one of graphene, carbon nanotubes, amorphous carbon, graphite and carbon black.
  • the outer surface of the lithium supplement material is coated with a second coating layer, and the second coating layer is used to enhance the ionic conductivity of the lithium supplement material.
  • the second coating layer is conducive to the outward transport of lithium ions in the lithium supplement material; at the same time, the second coating layer can also play an auxiliary role in enhancing ion transport inside the electrode.
  • the second coating layer can be a dense structure or a loose structure, and can be fully coated on the outer surface of the lithium supplement material or a non-fully coated layer on the outer surface of the lithium supplement material.
  • the material of the second coating layer includes at least one of a perovskite-type, a NASICON-type, a garnet-type or a polymer-type solid electrolyte.
  • the outer surface of the lithium supplement material is coated with a third coating layer, and the third coating layer is used to enhance the electronic conductivity of the lithium supplement material.
  • the third coating layer is conducive to reducing the impedance inside the electrode.
  • the third coating layer can also play an auxiliary role as a conductive agent inside the electrode.
  • the third coating layer can be a dense structure or a loose structure, and can be fully coated on the outer surface of the lithium supplement material or a non-fully coated layer on the outer surface of the lithium supplement material.
  • the outer surface of the lithium supplementing material is coated with at least one of a first coating layer, a second coating layer, and a third coating layer.
  • the outer surface of the lithium supplement material is coated with a first coating layer, a second coating layer and a third coating layer.
  • the first coating layer, the second coating layer and the third coating layer can be coated on the outer surface of the lithium supplement material in sequence, or the second coating layer, the first coating layer and the third coating layer can be coated on the outer surface of the lithium supplement material in sequence, or other forms of coating can be used, which is not limited in this application.
  • the present application provides a method for preparing a lithium supplement material.
  • the method for preparing a lithium supplement material includes step S1 and step S2.
  • the specific steps are as follows:
  • Step S1 mixing metal source A with an iron source and a lithium source to obtain solid I;
  • Step S2 heating the solid I to 800-900° C. under an inert gas atmosphere for 12-36 hours, and cooling after the heating to obtain Li x-na A a My O z .
  • the A metal source is at least one of a sodium source and a potassium source
  • the method for preparing the lithium supplement material includes steps S1-1 and S2-1, and the specific steps are as follows:
  • Step S1-1 mixing at least one of a sodium source and a potassium source with an iron source and a lithium source to obtain a solid I;
  • Step S2-1 in an inert gas atmosphere, heating the solid I to 800-900° C. for 12-36 hours, and cooling after the heating to obtain Li xa A a FeO 4 .
  • the raw materials such as the iron source, the sodium source and/or the potassium source, and the lithium source are mixed evenly to facilitate the formation of an ordered crystal structure during subsequent sintering.
  • the raw materials can be mixed evenly by ball milling.
  • an anhydrous, volatile organic solvent can also be added to the raw materials and stirred for a period of time until the organic solvent evaporates to obtain a uniformly mixed solid I.
  • the iron source includes one or a combination of at least two of ferric sulfate, ferric nitrate, ferric chloride, ferric citrate, ferric hydroxide, and ferric oxide.
  • the iron source may also be a ferrous compound, such as ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous citrate, ferrous hydroxide, ferrous oxide, or iron in other valence states, such as ferric iron tetroxide.
  • the iron may be converted into trivalent iron by adding an oxidant.
  • the sodium source includes one or a combination of at least two of sodium chloride, sodium carbonate, sodium hydroxide, sodium bicarbonate, sodium sulfate, sodium nitrate, sodium oxide, and sodium peroxide.
  • the potassium source includes one or a combination of at least two of potassium chloride, potassium carbonate, potassium hydroxide, potassium bicarbonate, potassium sulfate, potassium nitrate, and potassium oxide.
  • the lithium source includes one or a combination of at least two of lithium hydroxide, lithium oxide, lithium chloride, lithium nitrite, lithium nitrate, lithium oxalate, lithium carbonate and lithium acetate.
  • the raw materials for preparing the lithium supplement material include iron oxide, sodium hydroxide, and lithium hydroxide.
  • the raw materials for preparing the lithium supplement material include iron oxide, potassium hydroxide, and lithium hydroxide.
  • the raw materials for preparing the lithium supplement material include ferric chloride, sodium chloride, and lithium nitrate.
  • the raw materials for preparing the lithium supplement material include iron sulfate, potassium nitrate, and lithium chloride.
  • the raw materials for preparing the lithium supplement material include ferric nitrate, sodium sulfate, and lithium oxide.
  • the inert gas atmosphere can form a water-free and carbon dioxide-free reaction environment to prevent the external environment from affecting the preparation of Li xa A a FeO 4 lithium supplement material.
  • the inert gas includes at least one of argon, helium, and neon, and the gas atmosphere in step S2 can also be a non-inert gas such as nitrogen and oxygen.
  • the heating temperature and heating time of solid I are related to the formation of Li xa A a FeO 4 lithium-supplementing material and the formation of anti-fluorite crystal structure of Li xa A a FeO 4 lithium-supplementing material.
  • the temperature is controlled at 800-900°C and the heating time is controlled at 12-36 hours to prepare Li xa A a FeO 4 lithium-supplementing material with anti-fluorite structure.
  • the heating time can refer to the time after the solid I is heated to the preset temperature and maintained at the preset temperature.
  • the heating time can also refer to the time from the start of heating to the end of heating.
  • the heating temperature is 800-850°C, 810-860°C, 820-870°C, 830-880°C, 840-890°C, 850-895°C, 860-880°C, 870-890°C, 815-855°C, or 820-840°C.
  • the heating temperature is 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C.
  • the heating time can be 12-24 hours, 14-26 hours, 16-28 hours, 18-30 hours, 20-32 hours, 22-34 hours, 24-36 hours, 20-28 hours, 22-26 hours or 23-25 hours.
  • the heating time can be 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, or 36 hours.
  • the solid I is heated to 800°C and maintained at that temperature for 36 hours.
  • the solid I is heated to 820°C and maintained at this temperature for 30 hours.
  • the solid I is heated to 850°C and maintained at that temperature for 24 hours.
  • the solid I is heated to 870°C and maintained at this temperature for 20 hours.
  • the solid I is heated to 900°C and maintained at that temperature for 18 hours.
  • the heating rate of heating the solid I is 1-10°C/min.
  • the heating rate of heating the solid I is 1-5°C/min, 2-6°C/min, 3-7°C/min, 4-8°C/min, 5-9°C/min, 6-10°C/min or 4-6°C/min.
  • the heating rate of heating the solid I is 1°C/min, 2°C/min, 3°C/min, 4°C/min, 5°C/min, 6°C/min, 7°C/min, 8°C/min, 9°C/min or 10°C/min.
  • the solid I is heated to 850° C. at a heating rate of 5° C./min, kept at 850° C. for 24 hours, and naturally cooled to room temperature to obtain Li xa A a FeO 4 .
  • the A metal source may also be selected from other metal sources, for example, the A metal source is selected from an aluminum source, and the preparation method of the lithium supplement material includes step S1-2 and step S2-2, and the specific steps are as follows:
  • Step S1-2 mixing the aluminum source with the iron source and the lithium source to obtain solid I;
  • Step S2-2 in an inert gas atmosphere, heating the solid I to 800-900° C. for 12-36 hours, and cooling after the heating to obtain Li x-3a Al a FeO 4 .
  • the aluminum source includes one or a combination of at least two of aluminum chloride, aluminum carbonate, aluminum hydroxide, aluminum bicarbonate, aluminum sulfate, aluminum nitrate, and aluminum oxide.
  • the present application provides a positive electrode sheet, the positive electrode sheet includes the lithium supplement material as described above or the positive electrode sheet includes the lithium supplement material prepared by the preparation method of the lithium supplement material as described above.
  • the positive electrode sheet also includes the positive electrode material, and the positive electrode material and the lithium supplement material are mixed and then subjected to slurrying, coating, drying, rolling, and cutting operations to prepare the positive electrode sheet.
  • the positive electrode sheet includes a positive electrode sheet body and a lithium supplement material, and the lithium supplement material is coated on the outer surface of the positive electrode sheet body to obtain the positive electrode sheet.
  • the cathode material in the present application is not limited to phosphate cathode materials.
  • the cathode material includes but is not limited to lithium iron phosphate, lithium iron manganese phosphate, and ternary materials (lithium nickel cobalt manganese oxide (NCM) and lithium nickel cobalt aluminum oxide (NCA)).
  • the present application provides a battery, the battery comprising the positive electrode sheet as described above, or the battery comprising the lithium supplement material as described above, or the battery comprising the lithium supplement material prepared by the preparation method of the lithium supplement material as described above.
  • Fe 2 O 3 , NaOH and LiOH were prepared in a stoichiometric ratio of 0.5:0.5:4.5, and the raw materials were ball-milled to obtain solid I. Under the protection of argon atmosphere, the solid I was heated to 850°C at a heating rate of 5°C/min, kept at 850°C for 24 hours, and then naturally cooled to room temperature to obtain Li 4.5 Na 0.5 FeO 4 lithium-replenishing material.
  • the scanning electron microscope spectrum of the Li 4.5 Na 0.5 FeO 4 lithium-replenishing material is shown in Figure 2.
  • Fe 2 O 3 , NaOH and LiOH were prepared in a stoichiometric ratio of 0.5:1:4, and the raw materials were ball-milled to obtain solid I. Under the protection of argon atmosphere, the solid I was heated to 850°C at a heating rate of 5°C/min, kept at 850°C for 24 hours, and then naturally cooled to room temperature to obtain Li 4 NaFeO 4 lithium supplement material.
  • Fe 2 O 3 , KOH and LiOH were prepared in a stoichiometric ratio of 0.5:0.5:4.5, and the raw materials were ball-milled to obtain solid I; under the protection of argon atmosphere, the solid I was heated to 850°C at a heating rate of 5°C/min, kept at 850°C for 24 hours, and then naturally cooled to room temperature to obtain Li 4.5 K 0.5 FeO 4 lithium-supplementing material.
  • Fe 2 O 3 , NaOH, Al(OH) 3 and LiOH were prepared in a stoichiometric ratio of 0.5:1.7:0.1:3, and the raw materials were ball-milled to obtain solid I; under the protection of argon atmosphere, the solid I was heated to 850°C at a heating rate of 5°C/min, kept at 850°C for 24 hours, and then naturally cooled to room temperature to obtain Li 3 Na 1.7 Al 0.1 FeO 4 lithium-supplementing material.
  • Fe2O3 and LiOH were prepared in a stoichiometric ratio of 0.5 :5, and the raw materials were ball-milled to obtain solid I. Under the protection of argon atmosphere, the solid I was heated to 850°C at a heating rate of 5°C/min, kept at 850°C for 24 hours, and then naturally cooled to room temperature to obtain Li5FeO4 lithium supplement material.
  • the lithium supplement materials of Examples 1-4 and Comparative Example 1 were mixed with SP and PVDF at a mass ratio of 95:2:3, and an appropriate amount of NMP solvent was added and ball milled for 30 minutes; after homogenization, coating, drying, rolling, and cutting, positive electrode sheets were prepared respectively.
  • the positive electrode sheets were baked in a vacuum oven at 100°C to remove trace water.
  • the lithium metal sheet was used as the negative electrode, and the electrolyte was 1 mol/L LiPF 6 solution, the solvent is a mixture of EC (ethylene carbonate) and DEC (diethyl carbonate) in a volume ratio of 1:1, assembled into a CR2032 button lithium-ion battery.
  • the lithium-ion batteries provided in Examples 1-4 and Comparative Example 1 were tested for their charge and discharge capacity performance as follows: 0.1C rate constant current constant voltage charging to 4.3V, with a cut-off current of 0.02C; left for 5 minutes, and 0.1C rate constant current discharging to 2.8V.
  • the lithium replenishment efficiency in Examples 1-3 can also be maintained above 96%.
  • the lithium replenishment efficiency in Examples 1-3 is equivalent to that in Comparative Example 1, and the lithium replenishment efficiency in Example 3 is slightly higher than that in Comparative Example 1, indicating that the strategy of using alkali metals such as Na or K to replace the structural support of Li in the Li 5 FeO 4 lithium replenishment material can maintain a relatively high lithium replenishment performance while significantly reducing the material cost.
  • Example 4 It can be found from the electrochemical performance of Example 4 that too much Li is replaced, and the replacing elements will occupy part of the active lithium sites used for lithium replenishment, which will lead to the loss of effective lithium replenishment, and the lithium replenishment capacity and lithium replenishment efficiency will decrease significantly.
  • FIG 3 is a charging curve diagram of the lithium ion batteries provided in Examples 1-3 and Comparative Example 1. It can be seen from Figure 3 that the lithium ion batteries provided in Examples 1-3 and Comparative Example 1 will have two voltage platforms near 3.6V and 3.9V during the first charging process.
  • the lithium supplement material can remove 2 Li + at the low voltage platform, continue to charge to the high voltage platform, continue to remove 2 Li + , and then continue to increase the voltage without changing the gram capacity of the battery.
  • the voltage at the end point of the high voltage platform that is, the voltage of the inflection point from the high voltage charging platform to the gram capacity without change, is the minimum separation voltage of the lithium supplement material (in Examples 1-3) or the minimum separation voltage of Li5MO4 (in Comparative Example 1).
  • the minimum separation voltages of the lithium-replenishing materials in Examples 1-4 are 4.1V, 4.0V, 4.1V, and 4.0V, respectively, while the minimum separation voltage of Li 5 MO 4 in Comparative Example 1 is 4.2V.
  • the minimum separation voltage of Li 5 MO 4 in Comparative Example 1 is 4.2V.
  • the prepared lithium-replenishing material can achieve rapid lithium separation, which is more conducive to lithium replenishment of the battery system.
  • the lithium-supplementing material LixaAaMyOz provided in the present application significantly reduces the cost of the lithium - supplementing material while maintaining a good lithium-supplementing effect, thereby forming a cost-effective lithium-supplementing material.
  • the lithium in the lithium-supplementing material provided in the present application is easier to be released for lithium-supplementing, has a lower voltage platform, a narrower voltage window, a wider and more flexible application scenario, and has a higher application value.
  • the preparation method of the battery is as follows:
  • positive electrode sheet a lithium iron phosphate positive electrode, the lithium supplement material of Example 1, SP and PVDF were mixed in a mass ratio of 93:2:2:3 to prepare a positive electrode sheet, and a comparative sample was prepared by mixing a lithium iron phosphate positive electrode with SP and PVDF in a mass ratio of 95:2:3 to prepare a positive electrode sheet.
  • Negative electrode sheet Graphite is used as the negative electrode material.
  • Diaphragm PP diaphragm.
  • Electrolyte 1 mol/L LiPF6 solution, the solvent is a mixture of EC (ethylene carbonate) and DEC (diethyl carbonate) in a volume ratio of 1:1.
  • the positive electrode sheet, negative electrode sheet, electrolyte and separator were assembled into a lithium-ion soft pack battery according to the requirements of lithium-ion battery assembly, and charged to 3.5V at a constant current of 0.33C, left for 5 minutes, and then charged to 4.3V at a constant current and voltage of 0.33C, with a cut-off current of 0.1C.
  • the resulting battery charging curve is shown in Figure 4.
  • Figure 4 is a full battery charging curve diagram provided in the first embodiment of the present application. It can be found from Figure 4 that the first charge gram capacity of the pure lithium iron phosphate battery is 162.6 mAh/g, while the first charge gram capacity of the lithium iron phosphate battery with 2% lithium supplement material of Example 1 is 173.3 mAh/g, which plays a good lithium supplement role.

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Abstract

本申请提供一种补锂材料及其制备方法和应用，补锂材料应用在正极片和电池上，所述补锂材料的化学式为Lix-naAaMyOz，其中，A选自除Li以外的其他金属元素，M选自至少一种过渡金属元素，且1＜x≤8，y＞0，0＜z＜6，1≤n≤4，0＜a≤2。本申请中，将不能参与补锂过程的锂原子替换成其他金属，在保持较高的补锂效果的同时，大幅度降低补锂材料的成本，且能够实现锂离子的快速脱出。

Description

补锂材料及其制备方法和应用
本申请要求于2022年11月09日提交中国专利局、申请号为202211399493.1的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池技术领域，特别涉及一种补锂材料及其制备方法和应用。
背景技术
电池例如锂离子二次电池在首次充放电过程中，电池负极的表面会产生大量的固体电解质界面膜(SEI膜)，消耗电池中有限的锂离子和电解液，造成不可逆容量损失，降低锂离子二次电池的能量密度且降低了电极材料的充放电效率。而采用正极补锂添加剂作为锂离子的补充材料，在锂离子电池工作之前向电池内部增加锂来补充锂离子，但正极补锂添加剂在实际使用过程中部分锂不会脱出，基本不参与补锂过程，造成了锂元素的浪费，不利于正极补锂添加剂的推广应用。
发明内容
本申请提供一种补锂材料及其制备方法和应用，以解决锂元素的浪费的问题。
第一方面，本申请提供一种补锂材料，所述补锂材料的化学式为Lix-naAaMyOz，其中，A选自除Li以外的其他金属元素，M选自至少一种过渡金属元素，且1＜x≤8，y＞0，0＜z＜6，1≤n≤4，0＜a≤2。
在本申请中，将不能参与补锂过程的锂原子替换成其他金属，一方面，Lix-naAaMyOz可达到与LixMyOz同样的补锂效果，补锂材料补锂后，产物为锂含量较少或者不含锂的化合物，不会造成锂的较大浪费，本申请提供的补锂材料，可以在不损失补锂效果的同时，大幅度降低补锂材料的成本，形成高性价比的补锂材料，降低补锂材料的价格门槛，有助于正极补锂添加剂的推广，同时推动新能源产业发展进步；另一方面，可通过筛选A，使得A的原子半径大于Li的原子半径，将体积较小的不能参与补锂过程的锂原子替换为体积较大的A原子，在补锂材料制备过程中，更有利于锂进入反应体系以形成Lix-naAaMyOz结构，同时，在补锂材料使用过程中，A的原子半径大使得锂更容易脱出以便进行补锂。
在一实施方式中，A选自Na、K元素中的至少一种，所述补锂材料的化学式为Lix-aAaMyOz。
在本申请中，可以是将不能参与补锂过程的锂原子替换成价格更加低廉的Na和/或K等碱金属，一方面，Lix-aAaMyOz可达到与LixMyOz同样的补锂效果，在补锂材料中，Na、K和Li均为正一价，具有相同的价态，Na、K和Li性质相近，当用Na和/或K替换Li时，对补锂材料性质的改变不大，补锂材料中至少4个锂离子能够被用于对电池体系进行补锂，同时，补锂材料补锂后，产物为锂含量较少或者不含锂的钠、钾化合物，相较于Li，Na、K的价格较低，即使仅用作结构支撑，也不会造成较大的浪费，本申请提供的补锂材料，可以在不损失补锂效果的同时，大幅度降低补锂材料的成本，形成高性价比的补锂材料，降低补锂材料的价格门槛，有助于正极补锂添加剂的推广，同时推动新能源产业发展进步；另一方面，由于Na和K的原子半径大于Li的原子半径，将体积较小的不能参与补锂过程的锂原子替换为体积较大的Na和/或K原子，在补锂材料制备过程中，更有利于锂进入反应体系以形成Lix-aAaMyOz结构，同时，在补锂材料使用过程中，Na和K的原子半径大使得锂更容易脱出 以便进行补锂。
在一实施方式中，所述补锂材料的化学式为Li5-aAaMO4，且a≤1，M选自Fe、Co、Ni、Mn、Al、Cr、Ga、In、La、Bi中的至少一种。
在一实施方式中，所述补锂材料的晶体结构与Li5MO4的晶体结构相同。
在一实施方式中，所述补锂材料的本征密度为2-3.5g/cm3。
在一实施方式中，所述补锂材料的禁带宽度为1-4eV。
在一实施方式中，补锂材料的晶胞体积为
在一实施方式中，补锂材料的晶胞由40个原子组成。
在一实施方式中，所述补锂材料的化学式为Li4AMO4，所述补锂材料的的粒径为0.1-100微米。
在一实施方式中，所述补锂材料的最低脱离电压低于Li5MO4的最低脱离电压，所述补锂材料的最低脱离电压是指所述补锂材料中脱出四个锂离子的最低电压，所述Li5MO4的最低脱离电压是指Li5MO4中脱出四个锂离子的最低电压。
第二方面，本申请提供一种补锂材料的制备方法，所述补锂材料的制备方法包括：
将A金属源与铁源、锂源混合，获得固体Ⅰ；
在惰性气体氛围下，加热所述固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却后获得Lix-naAaMyOz。
在一实施方式中，A选自钠或者钾，A金属源为钠源和钾源中至少一种，补锂材料的制备方法包括：
将钠源和钾源中至少一种与铁源、锂源混合，获得固体Ⅰ；
在惰性气体氛围下，加热所述固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却后获得Lix-aAaFeO4。
在一实施方式中，所述铁源包括硫酸铁、硝酸铁、氯化铁、柠檬酸铁、氢氧化铁、氧化铁中的一种或至少两种的组合。
在一实施方式中，所述钠源包括氯化钠、碳酸钠、氢氧化钠、碳酸氢钠、硫酸钠、硝酸钠、氧化钠中的一种或至少两种的组合。
在一实施方式中，所述钾源包括氯化钾、碳酸钾、氢氧化钾、碳酸氢钾、硫酸钾、硝酸钾、氧化钾中的一种或至少两种的组合。
在一实施方式中，所述锂源包括氢氧化锂、氧化锂、氯化锂、亚硝酸锂、硝酸锂、草酸锂、碳酸锂和醋酸锂中的一种或至少两种的组合。
在一实施方式中，加热所述固体Ⅰ的加热速率为1-10℃/min。
第三方面，本申请提供一种正极片，所述正极片包括如上任一项所述的补锂材料或所述正极片包括如上任一项所述的补锂材料的制备方法制备得到的补锂材料。
第四方面，本申请提供一种电池，其特征在于，所述电池包括如上所述的正极片，或所述电池包括如上所述的补锂材料，或所述电池包括如上所述的补锂材料的制备方法制备得到的补锂材料。
本申请中，通过将不能参与补锂过程的锂原子替换成价格更加低廉的Na和/或K等金属，一方面，Lix-naAaMyOz具有较好的补锂效果，同时补锂材料的锂的利用率高，补锂材料补锂后，产物中锂含量较少或者不含锂，对锂的浪费减小，大幅度降低补锂材料的成本；另一方面，在补锂材料使用过程中，原子半径大的金属元素使得锂更容易脱出以便进行补锂。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对本申请实施例中所需要使用的附图进行说明。
图1为本申请一实施方式提供的补锂材料与Li5FeO4的XRD衍射谱图。
图2为本申请第一实施例提供的Li4.5Na0.5FeO4材料的SEM图像。
图3为实施例1-3和对比例1提供的锂离子电池的充电曲线图。
图4为本申请第一实施例提供的全电池充电曲线图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
本文中，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
此外，本文中，“上”、“下”等方位术语是相对于附图中的结构示意置放的方位来定义的，应当理解到，这些方向性术语是相对的概念，它们用于相对于的描述和澄清，其可以根据结构所放置的方位的变化而相应地发生变化。
为方便理解，下面先对本申请实施例所涉及的英文简写和有关技术术语进行解释和描述。
SEI膜：指Solid Electrolyte Interphase，即固体电解质界面膜。
SP：Super P，导电炭黑，一种导电剂。
PVDF：poly(vinylidene fluoride)，聚偏氟乙烯，一种黏结剂。
NMP：1-Methyl-2-pyrrolidinone，N-甲基吡咯烷酮，一种溶剂。
电池例如锂离子二次电池在首次充放电过程中，电池负极的表面会产生大量的固体电解质界面膜(SEI膜)，消耗电池中有限的锂离子和电解液，造成不可逆容量损失，降低锂离子二次电池的能量密度且降低了电极材料的充放电效率。而采用正极补锂添加剂作为锂离子的补充材料，在锂离子电池工作之前向电池内部增加锂来补充锂离子，一方面，对锂源需求量较大，成本较高，提高了正极补锂添加剂的价格门槛；另一方面，正极补锂添加剂在实际使用过程中部分锂不会脱出，基本不参与补锂过程，造成了锂元素的浪费，不利于正极补锂添加剂的推广应用。
本申请提供一种补锂材料，补锂材料应用在电池正极上，使正极预锂化，在电池工作之前向电池内部增加锂以补充锂离子。在一实施方式中，补锂材料应用时，可将补锂材料涂布至电池正极的外表面上，或者补锂材料嵌合至电池正极的外表面，在其他实施方式中，也可以在电池正极的制备过程中，添加补锂材料，使补锂材料分散至电池正极的外表面及内部。
补锂材料的含锂量高，在首次充电的过程中补锂材料的锂(Li)能够释放出来并迁移至电池负极，抵消形成SEI膜造成的不可逆锂损耗，以提高电池的总容量和能量密度。
本申请中，补锂材料的化学式为Lix-naAaMyOz，其中，A选自除Li以外的其他金属元素，M选自至少一种过渡金属元素，且1＜x≤8，y＞0，0＜z＜6，1≤n≤4，0＜a≤2。其中，n为A元素在Lix-naAaMyOz中的价态。
现有技术中的补锂材料的化学式通常为LixMyOz，由于补锂材料LixMyOz在使用过程中， 只有部分锂会脱出形成活性锂离子对电池体系进行补锂，剩余的部分锂则是作为材料结构支撑，基本不参与补锂过程，锂的利用率低。在本申请中，在Li位掺杂其他金属元素，一方面，Lix-naAaMyOz可达到与LixMyOz同样的补锂效果；另一方面，若A采用价格较低的金属元素，补锂材料补锂后，产物中不含锂或含较少的锂，大幅度降低补锂材料的成本，形成高性价比的补锂材料，降低补锂材料的价格门槛，有助于正极补锂添加剂的推广，同时推动新能源产业发展进步；再一方面，若A采用体积较锂大的金属元素，在补锂材料制备过程中，更有利于锂进入反应体系以形成Lix-naAaMyOz结构，同时，在补锂材料使用过程中，A原子半径大使得锂更容易脱出以便进行补锂。
在一实施方式中，A选自Na、K中的至少一种，补锂材料的化学式为Lix-aAaMyOz。
当A选自Na元素时，补锂材料的化学式为Lix-aNaaMyOz；当A选自K元素时，补锂材料的化学式为Lix-aKaMyOz；当A选自Na和K元素时，补锂材料的化学式为Lix-aNaa1Ka2MyOz，其中，a＝a1+a2。
在一实施方式中，补锂材料的化学式可为Li5-aAaFeO4、Li6-aAaMnO4、Li6-aAaCoO4、Li6-aAaZnO4等。
现有技术中的补锂材料的化学式通常为LixMyOz，现有技术中的补锂材料中不包含自Na、K原子，补锂材料在使用过程中，只有部分锂会脱出形成活性锂离子对电池体系进行补锂，剩余的部分锂则是作为材料结构支撑，基本不参与补锂过程，锂的利用率低。例如Li5FeO4补锂材料，在补锂过程中，每个分子可以释放出四个锂离子，方程式如下所示：
Li5FeO4→4Li++4e-+LiFeO2+O2；
每个Li5FeO4分子仅有四个锂离子可以得到利用，剩下一个锂不参与补锂过程，即在使用Li5FeO4作为补锂材料时，仅只有80％左右的锂会脱出形成活性锂离子对电池体系进行补锂，剩余20％左右的锂则作为材料结构支撑，基本不参与补锂过程，造成了锂的浪费。
而在本申请中，将不能参与补锂过程的锂原子替换成价格更加低廉的Na和/或K等碱金属，一方面，Lix-aAaMyOz可达到与LixMyOz同样的补锂效果，在补锂材料中，Na、K和Li均为正一价，具有相同的价态，Na、K和Li性质相近，当用Na和/或K替换Li时，对补锂材料性质的改变不大，例如，当补锂材料的化学式为Li4NaFeO4时，在补锂过程中，每个分子也可以释放出四个锂离子，方程式如下所示：
Li4NaFeO4→4Li++4e-+NaFeO2+O2；
补锂材料中所有的锂离子均被用于对电池体系进行补锂，同时，补锂材料补锂后，产物为NaFeO2，相较于Li，Na的价格较低，即使仅用作结构支撑，也不会造成较大的浪费，即本申请提供的补锂材料，可以在不损失补锂效果的同时，大幅度降低补锂材料的成本，形成高性价比的补锂材料，降低补锂材料的价格门槛，有助于正极补锂添加剂的推广，同时推动新能源产业发展进步；
另一方面，由于Na和K的原子半径大于Li的原子半径，将体积较小的不能参与补锂过程的锂原子替换为体积较大的Na和/或K原子，在补锂材料制备过程中，更有利于锂进入反应体系以形成Lix-aAaMyOz结构，同时，在补锂材料使用过程中，Na和K的原子半径大使得锂更容易脱出以便进行补锂。
值得注意的是，本申请中的锂的脱出和不能脱出均是基于电池的充放电的电压下来说的，一般而言，对于包含Li5FeO4补锂材料的电池的充放电电压一般为4.3V，在4.3V下仅能将Li5FeO4中的四个锂脱出，若需要脱出最后一个锂，则需将电压加大至5V以上，5V以上的电压并非是正常情况下电池的充放电的电压，本申请中仅考虑正常电池的充放电的电压下锂离 子的脱出情况。
由于Na和K的质量大于Li的质量，补锂材料中Na和K的含量增多意味着补锂材料的质量会增加，在实际应用中，可根据实际需要以平衡补锂材料的价格与质量，对Na和K的含量进行选择性应用，即将补锂材料应用于不需考虑质量的产品中时，Na和K的含量可相对增大，而对于产品需要小型化或者减重的应用场景，Na和K的含量可降低设计。
在一些具体实施方式中，A可选但不限于Na、K、Al、Fe中的至少一种，补锂材料的化学式可以为Li5-3aAlaFeO4、Li5-3aAlaFeb1Alb2O4、Li6-3aAlaMnO4、Li6-3aAlaCoO4、Li6-3aAlaZnO4、Li5-naAla1Naa2FeO4、Li6-naAla1Naa2MnO4、Li6-naAla1Naa2CoO4、Li6-naAla1Naa2ZnO4、Li5-naAla1Naa2Feb1Alb2O4、Li5-naAla1Ka2FeO4、Li5-naAla1Ka2Feb1Alb2O4、Li6-naAla1Ka2MnO4、Li6-naAla1Ka2CoO4、Li6-naAla1Ka2ZnO4、Li6-3aFeaMnO4、Li6-3aFeaCoO4、Li6-3aFeaZnO4、Li6-naFea1Naa2MnO4、Li6-naFea1Naa2CoO4、Li6-naFea1Naa2ZnO4、Li6-naFea1Ka2MnO4、Li6-naFea1Ka2CoO4、Li6-naFea1Ka2ZnO4等。其中，a1+a2＝a，n为平均价态，b1+b2＝1；例如，Li6-naAla1Naa2MnO4，n为a1个Al与a2个Na的平均价态。
在一实施方式中，补锂材料的化学式为Li5-aAaMO4，且a≤1，A选自Na、K中的至少一种，M选自Fe、Co、Ni、Mn、Al、Cr、Ga、In、La、Bi中的至少一种。在Li5MO4这类补锂材料中，仅有一个锂不能脱出，即仅有一个锂不能参与补锂过程，本申请中，将Li5MO4中至少部分不能脱出的锂替换成Na和/或K原子，制备出的Li5-aAaMO4补锂材料可具备较好的补锂效果，同时补锂材料的成本大幅度降低，在补锂材料使用过程中，补锂材料中的锂更容易脱出以便进行补锂。
在一实施方式中，0＜a≤0.5、0.5≤a≤1、0.1≤a≤0.2、0.25≤a≤0.5、0.3≤a≤0.6、0.4≤a≤0.8或0.45≤a≤0.65。
在一实施方式中，a可以为1、0.9、0.8、0.7、0.6、0.5、0.4、0.3、0.2、0.1、0.05。
在一实施方式中，补锂材料的化学式可以为Li4NaFeO4、Li4KFeO4、Li4NaNiO4、Li4KMnO4、Li4.5Na0.5FeO4、Li4.5K0.5CoO4、Li4Na0.5K0.5NiO4、Li4Na0.5K0.5FeO4、Li4Na0.8K0.2FeO4、Li4.2Na0.5K0.3FeO4、Li4.4K0.6CrO4、Li4.6Na0.4AlO4、Li4.8Na0.2CrO4。
在一实施方式中，补锂材料的本征密度为2-3.5g/cm3。补锂材料的本征密度等于补锂材料的质量除以补锂材料去除孔隙后的体积，即补锂材料的的压实密度。在本征密度过大或过小时，均不利于锂离子的嵌入脱出，在本实施方式中，将补锂材料的本征密度设置为2-3.5g/cm3，使得单位体积的补锂材料含有较多的锂可用于给电池补充锂离子，同时，补锂材料中的锂更容易脱出以便进行补锂。
在一实施方式中，补锂材料的本征密度为2-3g/cm3。
在一实施方式中，补锂材料的本征密度为2.5-3.5g/cm3。
在一实施方式中，补锂材料的本征密度可以为2、2.2、2.4、2.6、2.8、3、3.2、3.4或3.5g/cm3。
在一实施方式中，补锂材料的禁带宽度为1-4eV。禁带宽度是指一个带隙宽度，即补锂材料中价电子从价带跃迁到导带的最低能量。本实施方式中，将补锂材料的禁带宽度设置为1-4eV，使得补锂材料具有更高的导电率和锂离子扩散系数。
在一实施方式中，补锂材料的禁带宽度为1-2eV。
在一实施方式中，补锂材料的禁带宽度为2-3eV。
在一实施方式中，补锂材料的禁带宽度为3-4eV。
在一实施方式中，补锂材料的禁带宽度为1-3eV。
在一实施方式中，补锂材料的禁带宽度为2-4eV。
在一实施方式中，补锂材料的禁带宽度可为2、2.5、3、3.5、4eV。
在一实施方式中，补锂材料的晶胞体积为晶胞为构成晶体的最基本的几何单元。在本实施方式中，补锂材料的晶胞由40个原子组成。
在一实施方式中，补锂材料的晶胞体积为
在一实施方式中，补锂材料的晶胞体积为
在一实施方式中，补锂材料的晶胞体积为300、350、400、450或
请参阅图1，图1为本申请一实施方式提供的补锂材料与Li5FeO4的XRD衍射谱图，在一实施方式中，补锂材料的晶体结构与Li5MO4的晶体结构相同。其中Li5MO4的晶体结构为反萤石结构，属于正交晶系、Pbca空间点群。而本申请中的补锂材料Li5-aAaMO4与Li5MO4的晶体结构相同，也即补锂材料Li5-aAaMO4也具有反萤石结构，Li5-aAaMO4晶体属于正交晶系、Pbca空间点群。以Li5FeO4为例，从图1中可知，本申请中的补锂材料与Li5FeO4的特征峰高度重合，本申请中的补锂材料与Li5FeO4具有相同的晶体结构，说明将Li5FeO4中至少部分不能脱出的锂替换成Na和/或K原子后，制备出的Li5-aAaFeO4补锂材料并未改变Li5FeO4中原子连接关系及其构造，Li5-aAaFeO4补锂材料缺失部分锂后仍具有与Li5FeO4类似的补锂效果。
在一实施方式中，补锂材料的化学式为Li4AMO4，补锂材料的的粒径为0.1-100微米。其中，补锂材料的化学式可为Li4NaMO4、Li4KMO4或Li4Naa1Ka2MO4，其中a1+a2＝1，且0＜a1＜1,0＜a2＜1。
补锂材料的粒径为0.1-100微米可以指所有微粒的平均补锂材料粒径在0.1-100微米范围内，也可指补锂材料中所有微粒的最大粒径为100微米，最小粒径为0.1微米。若补锂材料的粒径太小，则补锂材料容易团聚，在给负极补充活性锂时补锂材料内部的锂的难以脱出，降低补锂材料的效果；而补锂材料的粒径太大时，补锂材料的分散性差，不利于配置补锂材料的浆料，且补锂材料涂布在电池正极上时，粒径大容易划伤铝箔。在本实施方式中，将补锂材料的粒径控制在0.1微米至100微米之间，在保证锂离子的快速脱出的同时，还能提高补锂材料的分散性，便于补锂材料的使用以及保护电极。
在一实施方式中，补锂材料的粒径可为0.1-10微米、0.1-50微米、1-20微米、10-25微米、10-80微米、20-90微米、30-50微米、40-60微米、50-75微米、60-100微米、70-100微米、0.5-5微米或5-25微米。
在一实施方式中，补锂材料的粒径可为0.1、0.5、1、5、10、15、25、30、35、40、45、50、60、70、80、90或100微米。
在一实施方式中，补锂材料的最低脱离电压低于Li5MO4的最低脱离电压，补锂材料的最低脱离电压是指补锂材料中脱出四个锂离子的最低电压，Li5MO4的最低脱离电压是指Li5MO4中脱出四个锂离子的最低电压。在Li5MO4中，由于不能脱出的锂的离子半径较小，其余四个锂在脱出时较为困难。而在本实施方式中，由于Na和K的离子半径大于Li的离子半径，将体积较小的不能参与补锂过程的锂原子替换为体积较大的Na和/或K原子，在补锂材料Li4AMO4使用过程中，Na和K的离子半径大使得锂更容易脱出，也即本申请提供的补锂材料的最低脱离电压低于Li5MO4的最低脱离电压。
在一实施方式中，至少部分所述补锂材料的外表面包覆有第一包覆层，第一包覆层用于将所述补锂材料与水分和二氧化碳隔绝。第一包覆层能够保护补锂材料，提高补锂材料的稳定性，以确保补锂材料的补锂作用，同时，保证补锂材料在电极活性浆料、活性层中补锂的稳定性和分散的均匀性以及良好的加工性能。第一包覆层可位于部分补锂材料的外表面，也 可包覆补锂材料的全部外表面，本申请对此不作限制。
在一实施方式中，第一包覆层材料包括陶瓷、高分子聚合物或碳材料中的至少一种。其中，陶瓷包括Al2O3、SiO2、勃姆石、Si3N4、SiC、BN中的至少一种；聚合物包括聚偏氟乙烯、海藻酸钠、羧甲基纤维素钠、聚丙烯酸、聚丙烯酸盐、聚丙烯腈、聚酰胺、聚酰亚胺、聚乙烯吡咯烷酮、聚氧化乙烯(PEO)、聚吡咯(PPy)、聚四氟乙烯(PTFE)、聚氨酯(PU)、羧甲基纤维素钠和聚丙烯酸中的一种或多种；碳材料包括石墨烯、碳纳米管、无定形碳、石墨、炭黑中的至少一种。
在一实施方式中，至少部分所述补锂材料的外表面包覆有第二包覆层，第二包覆层用于增强补锂材料的离子电导率。第二包覆层有利于补锂材料中的锂离子向外输运；同时，第二包覆层在电极内部还能起到增强离子传输的辅助作用。第二包覆层可以为致密结构，也可以是疏松结构，可以是全包覆在补锂材料外表面，也可以是非全包覆层在补锂材料外表面。
在一实施方式中，第二包覆层的材料包括钙钛矿型、NASICON型、石榴石型或聚合物型固态电解质中的至少一种。
在一实施方式中，至少部分所述补锂材料的外表面包覆有第三包覆层，第三包覆层用于增强补锂材料的电子电导率。第三包覆层有利于减小电极内部的阻抗，同时，第三包覆层在电极内部还可起到导电剂的辅助作用。第三包覆层可以为致密结构，也可以是疏松结构，可以是全包覆在补锂材料外表面，也可以是非全包覆层在补锂材料外表面。
在一实施方式中，所述补锂材料的外表面包覆有第一包覆层、第二包覆层、第三包覆层中的至少一种。
在一实施方式中，所述补锂材料的外表面包覆有第一包覆层、第二包覆层和第三包覆层。此时第一包覆层、第二包覆层和第三包覆层可依次包覆在补锂材料外表面，也可以为第二包覆层、第一包覆层和第三包覆层可依次包覆在补锂材料外表面，还可以为其他形式的包覆，本申请对此不作限制。
本申请提供一种补锂材料的制备方法，补锂材料的制备方法包括步骤S1和步骤S2，具体步骤如下所示：
步骤S1，将A金属源与铁源、锂源混合，获得固体Ⅰ；
步骤S2，在惰性气体氛围下，加热所述固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却后获得Lix-naAaMyOz。
在一实施方式中，A金属源为钠源和钾源中的至少一种，补锂材料的制备方法包括步骤S1-1和步骤S2-1，具体步骤如下所示：
步骤S1-1，将钠源和钾源中的至少一种与铁源、锂源混合，获得固体Ⅰ；
步骤S2-1，在惰性气体氛围下，加热固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却后获得Lix-aAaFeO4。
步骤S1-1中，将铁源、钠源和/或钾源、锂源等原料混合均匀，便于在后续烧结形成有序的晶体结构。在一实施方式中，可将原料通过球磨的方式混合均匀，在其他实施方式中，也可以在原料中加入无水、易挥发的有机溶剂，搅拌一段时间至有机溶剂挥发获得混合均匀的固体Ⅰ。
在一实施方式中，铁源包括硫酸铁、硝酸铁、氯化铁、柠檬酸铁、氢氧化铁、氧化铁中的一种或至少两种的组合。在其他实施方式中，铁源也可为亚铁化合物，如硫酸亚铁、硝酸亚铁、氯化亚铁、柠檬酸亚铁、氢氧化亚铁、氧化亚铁，或者为其他价态的铁，如四氧化三铁，在制备补锂材料时，通过加入氧化剂等将铁转化为三价铁即可。
在一实施方式中，钠源包括氯化钠、碳酸钠、氢氧化钠、碳酸氢钠、硫酸钠、硝酸钠、氧化钠、过氧化钠中的一种或至少两种的组合。
在一实施方式中，钾源包括氯化钾、碳酸钾、氢氧化钾、碳酸氢钾、硫酸钾、硝酸钾、氧化钾中的一种或至少两种的组合。
在一实施方式中，锂源包括氢氧化锂、氧化锂、氯化锂、亚硝酸锂、硝酸锂、草酸锂、碳酸锂和醋酸锂中的一种或至少两种的组合。
在一实施方式中，制备补锂材料的原料包括氧化铁、氢氧化钠、氢氧化锂。
在一实施方式中，制备补锂材料的原料包括氧化铁、氢氧化钾、氢氧化锂。
在一实施方式中，制备补锂材料的原料包括氯化铁、氯化钠、硝酸锂。
在一实施方式中，制备补锂材料的原料包括硫酸铁、硝酸钾、氯化锂。
在一实施方式中，制备补锂材料的原料包括硝酸铁、硫酸钠、氧化锂。
步骤S2-1中，惰性气体氛围可形成无水、无二氧化碳的反应环境，防止外界环境对制备Lix-aAaFeO4补锂材料的影响。在本实施方式中，惰性气体包括氩气、氦气、氖气中的至少一种，且步骤S2中的气体氛围也可以为氮气、氧气等非惰性气体。
对固体Ⅰ的加热温度与加热时间事关的Lix-aAaFeO4补锂材料形成以及Lix-aAaFeO4补锂材料形成反萤石晶体结构，在本实施方式中，将温度控制在800-900℃，加热时间控制在12-36小时，可以制备反萤石结构的Lix-aAaFeO4补锂材料。加热时间可以指将固体Ⅰ加热至预设温度后，在预设温度维持的时长，加热时间也可以指从开始加热至加热结束的时长。
在一实施方式中，加热温度为800-850℃、810-860℃、820-870℃、830-880℃、840-890℃、850-895℃、860-880℃、870-890℃、815-855℃、或820-840℃。
在一实施方式中，加热温度为800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃或900℃。
在一实施方式中，加热时间可以为12-24小时、14-26小时、16-28小时、18-30小时、20-32小时、22-34小时、24-36小时、20-28小时、22-26小时或23-25小时。
在一实施方式中，加热时间可以为12小时、14小时、16小时、18小时、20小时、22小时、24小时、26小时、28小时、30小时、32小时、34小时、36小时。
在一实施方式中，加热固体Ⅰ至800℃，保温36小时。
在一实施方式中，加热固体Ⅰ至820℃，保温30小时。
在一实施方式中，加热固体Ⅰ至850℃，保温24小时。
在一实施方式中，加热固体Ⅰ至870℃，保温20小时。
在一实施方式中，加热固体Ⅰ至900℃，保温18小时。
在一实施方式中，加热固体Ⅰ的加热速率为1-10℃/min。
在一实施方式中，加热固体Ⅰ的加热速率为1-5℃/min、2-6℃/min、3-7℃/min、4-8℃/min、5-9℃/min、6-10℃/min或4-6℃/min。
在一实施方式中，加热固体Ⅰ的加热速率为1℃/min、2℃/min、3℃/min、4℃/min、5℃/min、6℃/min、7℃/min、8℃/min、9℃/min或10℃/min。
在一实施方式中，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，自然冷却至室温，获得Lix-aAaFeO4。
在其他实施方式中，A金属源也可选自其他金属源，例如，A金属源选自铝源，补锂材料的制备方法包括步骤S1-2和步骤S2-2，具体步骤如下所示：
步骤S1-2，将铝源与铁源、锂源混合，获得固体Ⅰ；
步骤S2-2，在惰性气体氛围下，加热固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却后获得Lix-3aAlaFeO4。
在一实施方式中，铝源包括氯化铝、碳酸铝、氢氧化铝、碳酸氢铝、硫酸铝、硝酸铝、氧化铝中的一种或至少两种的组合。
本申请提供一种正极片，正极片包括如上所述的补锂材料或正极片包括如上所述的补锂材料的制备方法制备得到的补锂材料。在一实施方式中，正极片还包括正极材料，正极材料与补锂材料混合后经过匀浆、涂布、烘干、辊压、裁片操作，制备成正极片。在一实施方式中，正极片包括正极片主体和补锂材料，补锂材料涂覆在正极片主体的外表面，以获得正极片。
在一实施方式中，本申请中的正极材料不限于磷酸盐正极材料。在一实施方式中，正极材料包括但不限于磷酸铁锂、磷酸锰铁锂、三元材料(镍钴锰酸锂(NCM)和镍钴铝酸锂(NCA))。
本申请提供一种电池，电池包括如上所述的正极片，或电池包括如上所述的补锂材料，或电池包括如上所述的补锂材料的制备方法制备得到的补锂材料。
实施例1
将Fe2O3、NaOH和LiOH按照化学计量比0.5∶0.5∶4.5的比例进行配料，并对原料进行球磨混合，获得固体Ⅰ；在氩气气氛保护下，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，随后自然冷却至室温，获得Li4.5Na0.5FeO4补锂材料，Li4.5Na0.5FeO4补锂材料的扫描电镜图谱如图2所示。
实施例2
将Fe2O3、NaOH和LiOH按照化学计量比0.5∶1∶4的比例进行配料，并对原料进行球磨混合，获得固体Ⅰ；在氩气气氛保护下，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，随后自然冷却至室温，获得Li4NaFeO4补锂材料。
实施例3
将Fe2O3、KOH和LiOH按照化学计量比0.5∶0.5∶4.5的比例进行配料，并对原料进行球磨混合，获得固体Ⅰ；在氩气气氛保护下，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，随后自然冷却至室温，获得Li4.5K0.5FeO4补锂材料。
实施例4
将Fe2O3、NaOH、Al(OH)3和LiOH按照化学计量比0.5∶1.7∶0.1∶3的比例进行配料，并对原料进行球磨混合，获得固体Ⅰ；在氩气气氛保护下，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，随后自然冷却至室温，获得Li3Na1.7Al0.1FeO4补锂材料。
对比例1
将Fe2O3和LiOH按照化学计量比0.5∶5的比例进行配料，并对原料进行球磨混合，获得固体Ⅰ；在氩气气氛保护下，将固体Ⅰ以5℃/min的升温速率升至850℃，于850℃保温24小时，随后自然冷却至室温，获得Li5FeO4补锂材料。
将实施例1-4和对比例1的补锂材料制备成电池，进行相关性能测试，电池的制备过程以及测试结果如下所示：
将实施例1-4和对比例1的补锂材料分别与SP和PVDF以95:2:3质量比混合，加入适量NMP溶剂球磨搅拌30分钟；经过匀浆、涂布、烘干、辊压、裁片操作，分别制备成正极片，正极片在100℃真空烘箱中烘烤，除去痕量水。以锂金属片为负极，电解液采用1mol/L的 LiPF6溶液，溶剂为体积比1:1的EC(碳酸乙烯酯)和DEC(碳酸二乙酯)混合物，组装成CR2032型扣式锂离子电池。
将实施例1-4和对比例1提供的锂离子电池分别按照如下方法测试其充放电克容量性能：0.1C倍率恒流恒压充电至4.3V，截止电流为0.02C；搁置5min，0.1C倍率恒流放电至2.8V。
相关性能测试结果如下表1中所示：
表1性能测试结果
通过实施例1-3和对比例1的电化学性能比较可以发现，由于Li5FeO4材料中部分Li被Na或K取代，由于Na和K的原子质量高于Li，所以对材料的补锂克容量会存在一定的损失，但都维持在较高的水平。
同时实施例1-3中补锂效率也都可以保持96％以上，实施例1-3中补锂效率与对比例1中的补锂效率相当，且在实施例3中的补锂效率略高于对比例1中的补锂效率，说明在Li5FeO4补锂材料中使用Na或K的碱金属替代部分起到结构支撑作用Li的策略可以保持较高的补锂性能，同时大幅度降低材料成本。
通过实施例4的电化学性能可以发现，过多的Li被取代，取代元素会占据部分用于补锂作用的活性锂位点，反而导致有效补锂量损失，补锂克容量和补锂效率都下降明显。
请参阅图3，图3为实施例1-3和对比例1提供的锂离子电池的充电曲线图，从图3可知，实施例1-3和对比例1提供的锂离子电池在在首次充电的过程中均会在3.6V和3.9V附近出现两个电压平台，在低压电压平台补锂材料可脱去2个Li+，继续充电到至高压电压平台，继续脱去2个Li+，而后继续增大电压电池的克容量不发生变化，在高压电压平台的终点的电压，也即高压充电平台至克容量不发生变化时的拐点的电压即为补锂材料的最低脱离电压(实施例1-3中)或Li5MO4的最低脱离电压(对比例1中)。
实施例1-4中补锂材料的最低脱离电压分别为4.1V、4.0V、4.1V、4.0V，而对比例1中Li5MO4的最低脱离电压为4.2V，本申请中，将Li5MO4中至少部分不能脱出的锂替换成Na和/或K原子后，引入缺陷，撑大晶体中离子迁移通道，制备出的补锂材料能够实现快速脱锂，更有利于对电池体系进行补锂。
综上所述，本申请提供的补锂材料Lix-aAaMyOz，在保持较好的补锂效果的同时，大幅度降低补锂材料的成本，形成高性价比的补锂材料，且本申请提供的补锂材料中的锂更容易脱出以便进行补锂，电压平台更低，电压窗口更窄，应用场景更广泛更灵活，具有较高的应用价值。
补锂材料作为正极补锂添加剂应用在电池中时，电池的制备方法如下所示：
1)正极片的制备：磷酸铁锂正极、实施例1补锂材料与SP和PVDF以93:2:2:3质量比混合制备正极片，对比样品以磷酸铁锂正极与SP和PVDF以95:2:3质量比混合制备正极片。
2)负极片：以石墨为负极材料。
3)隔膜：PP隔膜。
4)电解液：1mol/L的LiPF6溶液，溶剂为体积比1:1的EC(碳酸乙烯酯)和DEC(碳酸二乙酯)混合物。
5)二次电池的组装：11片双面负极片配10片双面正极片，采用叠片工艺。
将上述正极片、负极片、电解液和隔膜按照锂离子电池组装要求组装成锂离子软包电池，以0.33C倍率恒流充电至3.5V，搁置5min，再继续以0.33C倍率恒流恒压充电至4.3V，截止电流为0.1C。所得电池充电曲线图如图4所示。
请参阅图4，图4为本申请第一实施例提供的全电池充电曲线图，从图4中可以发现，纯磷酸铁锂电池首次充电克容量发挥为162.6mAh/g，而添加2％实施例1补锂材料的磷酸铁锂电池首次充电克容量发挥为173.3mAh/g，起到了很好的补锂作用。
以上对本申请实施例所提供的补锂材料及其制备方法和应用进行了详细介绍，本文中应用了具体个例对本申请的原理及实施例进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的一般技术人员，依据本申请的思想，在具体实施例及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (19)

  1. 一种补锂材料，其特征在于，所述补锂材料的化学式为Lix-naAaMyOz，其中，A选自除Li以外的其他金属元素，M选自至少一种过渡金属元素，且1＜x≤8，y＞0，0＜z＜6，1≤n≤4，0＜a≤2。
  2. 根据权利要求1所述的补锂材料，其特征在于，所述补锂材料的化学式为Li5-aAaMO4，且a≤1，A选自Na、K中的至少一种，M选自Fe、Co、Ni、Mn、Al、Cr、Ga、In、La、Bi中的至少一种。
  3. 根据权利要求2所述的补锂材料，其特征在于，所述补锂材料的晶体结构与Li5MO4的晶体结构相同。
  4. 根据权利要求2所述的补锂材料，其特征在于，所述补锂材料的晶胞体积为
  5. 根据权利要求2所述的补锂材料，其特征在于，所述补锂材料的晶胞由40个原子组成。
  6. 根据权利要求2所述的补锂材料，其特征在于，所述补锂材料的本征密度为2-3.5g/cm3，禁带宽度为1-4eV。
  7. 根据权利要求2所述的补锂材料，其特征在于，所述补锂材料的化学式为Li4AMO4。
  8. 根据权利要求7所述的补锂材料，其特征在于，所述补锂材料的最低脱离电压低于Li5MO4的最低脱离电压，所述补锂材料的最低脱离电压是指所述补锂材料中脱出四个锂离子的最低电压，所述Li5MO4的最低脱离电压是指Li5MO4中脱出四个锂离子的最低电压。
  9. 根据权利要求1所述的补锂材料，其特征在于，所述补锂材料的的粒径为0.1-100微米。
  10. 根据权利要求1所述的补锂材料，其特征在于，所述补锂材料的外表面包覆有第一包覆层、第二包覆层、第三包覆层中的至少一种；其中，所述第一包覆层用于将所述补锂材料与水分和二氧化碳隔绝，所述第二包覆层用于增强所述补锂材料的离子电导率，所述第三包覆层用于增强所述补锂材料的电子电导率。
  11. 根据权利要求10所述的补锂材料，其特征在于，所述第一包覆层包括陶瓷、高分子聚合物或碳材料中的至少一种。
  12. 根据权利要求10所述的补锂材料，其特征在于，所述第二包覆层包括钙钛矿型、NASICON型、石榴石型或聚合物型固态电解质中的至少一种。
  13. 根据权利要求10所述的补锂材料，其特征在于，所述补锂材料的外表面依次包覆有所述第一包覆层、所述第二包覆层和所述第三包覆层。
  14. 根据权利要求10所述的补锂材料，其特征在于，所述补锂材料的外表面依次包覆有所述第二包覆层、所述第一包覆层和所述第三包覆层。
  15. 一种补锂材料的制备方法，其特征在于，所述补锂材料的制备方法包括：
    将A金属源与铁源、锂源混合，获得固体Ⅰ；
    在惰性气体氛围下，加热所述固体Ⅰ至800-900℃，加热时间为12-36小时，加热完成后冷却获得Lix-naAaMyOz。
  16. 根据权利要求15所述的补锂材料的制备方法，其特征在于，加热所述固体Ⅰ的加热速率为1-10℃/min。
  17. 根据权利要求15所述的补锂材料的制备方法，其特征在于，所述铁源包括硫酸铁、硝酸铁、氯化铁、柠檬酸铁、氢氧化铁、氧化铁中的一种或至少两种的组合；
    所述A金属源包括氯化钠、碳酸钠、氢氧化钠、碳酸氢钠、硫酸钠、硝酸钠、氧化钠、氯化钾、碳酸钾、氢氧化钾、碳酸氢钾、硫酸钾、硝酸钾、氧化钾中的一种或至少两种的组 合；
    所述锂源包括氢氧化锂、氧化锂、氯化锂、亚硝酸锂、硝酸锂、草酸锂、碳酸锂和醋酸锂中的一种或至少两种的组合。
  18. 一种正极片，其特征在于，所述正极片包括如权利要求1-14任一项所述的补锂材料或所述正极片包括如权利要求15-17任一项所述的补锂材料的制备方法制备得到的补锂材料。
  19. 一种电池，其特征在于，所述电池包括如权利要求18所述的正极片，或所述电池包括如权利要求1-14任一项所述的补锂材料，或所述电池包括如权利要求15-17任一项所述的补锂材料的制备方法制备得到的补锂材料。
PCT/CN2023/127143 2022-11-09 2023-10-27 补锂材料及其制备方法和应用 WO2024099106A1 (zh)

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