WO2023125171A1 - 负极材料及其制备方法、锂离子电池 - Google Patents

负极材料及其制备方法、锂离子电池 Download PDF

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WO2023125171A1
WO2023125171A1 PCT/CN2022/140481 CN2022140481W WO2023125171A1 WO 2023125171 A1 WO2023125171 A1 WO 2023125171A1 CN 2022140481 W CN2022140481 W CN 2022140481W WO 2023125171 A1 WO2023125171 A1 WO 2023125171A1
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lithium
negative electrode
silicon
silicate
electrode material
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PCT/CN2022/140481
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English (en)
French (fr)
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谢维
庞春雷
邓志强
任建国
贺雪琴
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贝特瑞新材料集团股份有限公司
惠州市鼎元新能源科技有限公司
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Application filed by 贝特瑞新材料集团股份有限公司, 惠州市鼎元新能源科技有限公司 filed Critical 贝特瑞新材料集团股份有限公司
Priority to JP2023560098A priority Critical patent/JP2024512113A/ja
Priority to US18/284,875 priority patent/US20240182314A1/en
Priority to EP22914425.8A priority patent/EP4300631A1/en
Priority to KR1020237033725A priority patent/KR20230152736A/ko
Publication of WO2023125171A1 publication Critical patent/WO2023125171A1/zh

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Definitions

  • the disclosure relates to the field of lithium-ion batteries, and relates to negative electrode materials, preparation methods thereof, and lithium-ion batteries.
  • Silicon oxide material is an essential negative electrode material in the development of a new generation of ultra-large capacity lithium-ion batteries.
  • the silicon oxide industry has been researching and laying out the development of silicon-based lithium-ion batteries for more than ten years.
  • silicon-based materials represented by silicon oxide have not been used on a large scale.
  • the main factor limiting the application of silicon-based materials is the natural disadvantages of silicon-based materials themselves. High expansion and drastic volume change, low first effect, magnification, etc. are all problems that need to be solved urgently.
  • Metal doping of the silicon-based core is one of the most direct improvements to improve the first-efficiency performance of silicon-based anode materials.
  • inactive silicate is formed, thereby avoiding the formation of inactive lithium silicate by the interaction between active lithium and oxygen during the lithium intercalation process, and improving the first effect of silicon-oxygen materials.
  • doping metals it is required to have certain reducibility, such as Li, Mg, etc.
  • Lithium metal is one of the best choices.
  • silicon-based materials form inactive materials such as lithium silicates of various phases inside after pre-lithiation. Outside the buffer zone in the process, the high lithium content at the interface can also act as a fast ion conductor to promote the rapid transfer of lithium ions inside.
  • the pre-lithiation process has been recognized as one of the most efficient ways to improve the first effect of silicon-based materials.
  • the present disclosure provides a negative electrode material, the negative electrode material includes an active material, and the active material includes a skeleton structure penetrating through the active material and a silicon oxide material embedded on the skeleton structure; the skeleton structure includes a A lithium silicate skeleton inside the active material and a water-insoluble silicate skeleton located on the surface of the active material, the water-insoluble silicate skeleton being connected to the lithium silicate skeleton;
  • the intensity of the strongest diffraction characteristic peak of the lithium silicate is I A
  • the intensity of the strongest diffraction characteristic peak of the water-insoluble silicate is I B
  • 0.03 ⁇ IB / IA ⁇ 0.2 is 0.03 .
  • the present disclosure also provides a negative electrode material, the negative electrode material including an active material
  • the active material includes lithium silicate, water-insoluble silicate and silicon-oxygen material
  • the water-insoluble silicate is coated on the surface of the lithium silicate
  • the silicon-oxygen material is contained in the lithium silicate and/or the water-insoluble silicate,
  • the intensity of the strongest diffraction characteristic peak of the lithium silicate is I A
  • the intensity of the strongest diffraction characteristic peak of the water-insoluble silicate is I B
  • 0.03 ⁇ IB / IA ⁇ 0.2 is 0.03 .
  • the silicon-oxygen material is SiO n , where 0.5 ⁇ n ⁇ 1.5.
  • the lithium silicate includes Li 2 SiO 3 , Li 2 Si 2 O 5 , Li 4 SiO 4 , Li 2 Si 3 O 7 , Li 8 SiO 6 , Li 6 Si 2 O 7 , Li 4 Si 2 At least one of O 7 , Li 2 Si 4 O 7 and LiSiO 3 .
  • the water-insoluble silicate includes zA 2 O ⁇ MO y ⁇ xSiO 2 , wherein M includes Mg, Al, Ca, Ge, Cr, V, Ti, Sc, Co, Ni, Cu, Sr , at least one of Zn, Zr, Fe and Mn, A includes at least one of Li, Na and K, 0.2 ⁇ x ⁇ 10.0, 1.0 ⁇ y ⁇ 3.0, 0 ⁇ z ⁇ 5.0.
  • the water-insoluble silicate further includes A 2 O ⁇ nSiO 2 , wherein A includes at least one of Li, Na, and K, and 1 ⁇ n ⁇ 10.
  • the work function range of the water-insoluble silicate is 2.5eV ⁇ 7.0eV.
  • the water-insoluble silicate is located within a depth region of 20 nm to 50 nm on the surface of the active material.
  • the mass content of Li element in the water-insoluble silicate is W 1 %
  • the Li element content in the lithium silicate is W 2 %
  • the negative electrode material further includes a carbon layer existing on the surface of the active material.
  • the average thickness of the carbon layer is 30nm-500nm.
  • the tap density of the negative electrode material is 0.6g/cm 3 -1.20g/cm 3 .
  • the specific surface area of the negative electrode material is 1.00m 2 /g ⁇ 12.0m 2 /g.
  • the average particle diameter of the negative electrode material is 3.0 ⁇ m ⁇ 12.0 ⁇ m.
  • the mass percentage content of carbon in the negative electrode material is 1.5wt%-10.0wt%.
  • the mass percent content of lithium in the negative electrode material is 3wt% ⁇ 15wt%.
  • the pH of the negative electrode material is 8.5-12.0.
  • the intensity of the strongest diffraction characteristic peak of lithium silicate is I A
  • the intensity of the strongest diffraction characteristic peak of water-insoluble silicate is I B
  • the lithium element content in the water-insoluble silicate of the negative electrode material is pm
  • the total lithium element content of the negative electrode material is p Li , wherein 0.01 ⁇ pm/p Li ⁇ 0.6 .
  • the present disclosure also provides a preparation method of negative electrode material, comprising the following steps:
  • the negative electrode material is obtained by mixing the surface-etched silicon-oxygen material with a substance containing metal M and/or metal A, and performing a solid-phase thermal reaction under a protective atmosphere.
  • the substance containing metal A includes: at least one of metal A simple substance, metal A carbonate, metal A oxide, and metal A hydroxide, wherein A includes Li, Na, K at least one of the
  • the metal M-containing substance includes at least one of metal M simple substance, metal M carbonate, metal M oxide, and metal M hydroxide, wherein M includes Mg, Al, Ca , Ge, Cr, Pb, Sr, Zn, Zr, Fe and Mn at least one.
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the substance containing metal M and/or metal A is 1:(0.01 ⁇ 0.1).
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the substance containing metal M and/or metal A is 1:(0.075 ⁇ 0.1).
  • the present disclosure also provides a preparation method of negative electrode material, comprising the following steps:
  • the silicon-oxygen material after the surface etching treatment is mixed with the compound containing metal M, and a solid-phase thermal reaction is carried out under a protective atmosphere to obtain the negative electrode material.
  • the metal M-containing compound includes at least one of metal M carbonate, metal M oxide, and metal M hydroxide, wherein M includes Mg, Al, Ca, Ge, Cr , at least one of Pb, Sr, Zn, Zr, Fe and Mn.
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the compound containing the metal M is 1:(0.01 ⁇ 0.1).
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the compound containing the metal M is 1:(0.075 ⁇ 0.1).
  • the compound containing metal M is an oxide of metal M.
  • the mixing method includes at least one of mechanical stirring, ultrasonic dispersion and grinding dispersion.
  • the mixing method is ball milling, and the ball milling time is 3h-24h.
  • the gas in the protective atmosphere includes at least one of nitrogen, helium, neon, argon, krypton and xenon.
  • the temperature of the solid-phase thermal reaction is 600°C-1200°C.
  • the time for the solid phase thermal reaction is 3h-12h.
  • the heating rate of the solid-phase thermal reaction is 1° C./min ⁇ 5° C./min.
  • the pre-lithiated silicon-oxygen material is a pre-lithiated carbon-coated silicon-oxygen material.
  • the pre-lithiated carbon-coated silicon-oxygen material is obtained by reacting a carbon-coated silicon-oxygen material with a lithium source.
  • the silicon-oxygen material is SiO n , where 0.5 ⁇ n ⁇ 1.5.
  • the average particle size (D 50 ) of the silicon-oxygen material is 2.0 ⁇ m-15.0 ⁇ m.
  • the thickness of the carbon layer on the surface of the carbon-coated silicon-oxygen material is 30nm-500nm.
  • the lithium source includes at least one of lithium elemental substance or lithium-containing compound.
  • the lithium source includes at least one of lithium hydride, lithium alkyl, lithium metal, lithium aluminum hydride, lithium amide and lithium borohydride.
  • reaction temperature between the carbon-coated silicon-oxygen material and the lithium source is 150°C to 300°C.
  • reaction time between the carbon-coated silicon-oxygen material and the lithium source is 2.0 hours to 6.0 hours.
  • the mass ratio of the carbon-coated silicon-oxygen material to the lithium source is 1:(0.01 ⁇ 0.20).
  • the mass percent content of lithium in the pre-lithiated carbon-coated silicon-oxygen material is 3wt%-20wt%.
  • the method before performing surface etching treatment on the pre-lithiated silicon-oxygen material, the method further includes:
  • a prelithiated silicon oxide material obtained by reacting a silicon oxide material with a lithium source
  • a pre-lithiated carbon-coated silicon-oxygen material obtained by reacting a carbon-coated silicon-oxygen material with a lithium source.
  • the acid solution used in the surface etching treatment has the characteristic that: when performing the surface etching treatment on the pre-lithiated silicon-oxygen material, the pH of the surface etching reaction system is kept ⁇ 7.
  • the acid solution used in the surface etching treatment includes hydrochloric acid, acetic acid, nitric acid, citric acid, oxalic acid, sulfuric acid, formic acid, phenol, phosphoric acid, hydrogen phosphate, hydroiodic acid, hydrobromic acid, ethylenediaminetetra At least one of acetic acid, glycolic acid, gluconic acid, and succinic acid.
  • the time for the surface etching treatment is 0.5-10.0 hours.
  • the present disclosure also provides a lithium ion battery, which comprises the negative electrode material described in the above first aspect or the negative electrode material prepared according to the preparation method of the negative electrode material described in the above first aspect.
  • Fig. 1 is the process flow chart of the preparation method of negative electrode material provided by the present disclosure
  • FIG. 2 is a schematic structural view of the negative electrode material provided by the present disclosure
  • FIG. 3 is a schematic structural view of the negative electrode material provided by the present disclosure.
  • FIG. 4 is a schematic diagram of the change of the capacity retention rate of the negative electrode material prepared by the embodiment of the present disclosure and the comparative example as the number of cycles increases;
  • FIG. 5 is a schematic diagram of the change in conductivity of the negative electrode material prepared in the embodiment of the present disclosure and the comparative example;
  • Fig. 6 is the XRD diffraction pattern of the negative electrode material that the embodiment 3 of the present disclosure makes;
  • the disclosure provides a negative electrode material, a preparation method thereof, and a lithium ion battery.
  • the negative electrode material of the present disclosure can improve processing performance, have excellent electrochemical cycle and expansion inhibition performance, prolong the service life of the lithium ion battery, and reduce production costs.
  • the negative electrode material includes an active material, and the active material includes a skeleton structure penetrating through the active material and a silicon-oxygen material embedded in the skeleton structure; the skeleton structure includes a lithium silicate skeleton located inside the active material And the skeleton of the water-insoluble silicate located on the surface of the active material, the skeleton of the water-insoluble silicate is connected to the skeleton of lithium silicate; Among them, in the XRD spectrum of the negative electrode material, the strongest diffraction characteristic peak of lithium silicate is The intensity is I A , the intensity of the strongest diffraction characteristic peak of the water-insoluble silicate is I B , and 0.03 ⁇ IB / IA ⁇ 0.2 .
  • the range of I B /I A can be, for example, 0.05 ⁇ I B /I A ⁇ 0.2, 0.1 ⁇ I B /I A ⁇ 0.2, 0.12 ⁇ I B /I A ⁇ 0.18 or 0.14 ⁇ I B /I A ⁇ 0.16 .
  • the term "skeleton” refers to the main substance (such as the weight of the main substance accounting for than the total weight of the structure is greater than or equal to 51%), in other words, it can be understood that the main substance is used as a basic substance to support, form or constitute a certain structure; for example, “the skeleton of lithium silicate” can be understood as lithium silicate is formed
  • the main component of the structure of lithium silicate is the basic substance that supports, forms or constitutes the structure of lithium silicate, and the structure of lithium silicate can be dispersed/embedded with other components (such as the silicon-oxygen material disclosed herein); for example, "Skeleton of water-insoluble silicate” can be understood as, water-insoluble silicate is the main component forming the structure of water-insoluble silicate, and is the basis for supporting, forming or forming the structure of water-insoluble silicate
  • the substance, the structure in which the water-insoluble silicate resides, may have other components dispersed/embedded therein (such as the
  • the negative electrode material includes an active material 100;
  • the active material 100 includes lithium silicate 120, water-insoluble silicate 140 and silicon-oxygen material 160;
  • the water-insoluble silicate 140 is coated on the surface of the lithium silicate 120;
  • the silicon-oxygen material 160 is contained in the lithium silicate 120 and/or the water-insoluble silicate 140,
  • the intensity of the strongest diffraction characteristic peak of the lithium silicate is I A
  • the intensity of the strongest diffraction characteristic peak of the water-insoluble silicate is I B
  • 0.03 ⁇ IB / IA ⁇ 0.2 is 0.03 .
  • the pre-lithiated silicon-oxygen material is etched on the surface (the material mainly includes lithium silicate 120, usually the inner core includes lithium silicate 120, and a silicon oxide layer is formed on the surface), which is non-
  • the formation of water-soluble silicates leaves pores, and subsequently reacts with metal M and/or metal A-containing substances to obtain a structure of water-insoluble silicate-coated lithium silicate 120;
  • the silicon-based disproportionation of the pre-lithiated silicon-oxygen material undergoes subsequent high-temperature treatment, forming a structure in which the silicon-oxygen material 160 is dispersed or embedded in the lithium silicate 120 and/or the water-insoluble silicate 140 .
  • water-insoluble silicates 140 include, but are not limited to, silicates that are insoluble in polar solutions, such as aqueous solutions.
  • the silicon-oxygen material (or called silicon-based active material) includes at least one of nano-silicon, silicon oxide, silicon carbide, silicon nitride, silicon sulfide or silicon alloy.
  • the negative electrode material further includes a coating layer 200 covering the surface of the active material 100 .
  • the silicon-oxygen material (or silicon-based active material, including nano-silicon, silicon oxide, silicon carbide, silicon nitride, silicon sulfide or silicon alloy, etc.) Skeleton) structure
  • the outer water-insoluble silicate and the inner lithium silicate are silicates of different crystal forms grown on the same silicon-oxygen skeleton, and the silicates of two different materials are connected, which is beneficial to
  • the electrochemical performance of the active material can quickly carry out electron transfer and deintercalation of lithium, which is conducive to reducing the internal resistance of the material and improving the lithium ion transfer ability.
  • the encapsulation of the silicon-oxygen material by the skeleton of the water-insoluble silicate located on the outer layer can effectively prevent the contact of water with the strong alkaline lithium silicate and inhibit the hydrolysis of lithium silicate, thereby effectively improving the gas production of the material and realizing the protection of the material. pH control to improve processing performance.
  • the lithium silicate in the inner layer and the water-insoluble silicate in the outer layer are closely connected through silicon and silicon-oxygen materials. The difference in work function of the two silicate materials leads to the formation of a heterojunction interface between the two, which can Improve electron transfer efficiency, thereby increasing lithium intercalation depth, improving capacity and cycle performance.
  • Lithium silicate and water-insoluble silicate are silicates of different crystal forms grown on the same silicon-oxygen skeleton, which can form a tight heterojunction interface without forming a vacuum section, which is beneficial to the electron exchange between heterojunction materials.
  • the transfer realizes the effective conduction of lithium ions through the skeleton structure and the silicon-oxygen material on the surface of the active material, which improves the ionic conductivity of the material and is conducive to the exertion of the rate performance of the material.
  • the silicon-oxygen material is SiO n , where 0.5 ⁇ n ⁇ 1.5.
  • the silicon-oxygen material may be SiO n such as SiO 0.5 , SiO 0.8 , SiO 0.9 , SiO, SiO 1.1 , SiO 1.2 or SiO 1.5 and so on.
  • the silicon-oxygen material is SiO. It can be understood that the composition of SiO n is relatively complex, and it can be understood that it is formed by uniformly dispersing nano-silicon in SiO 2 .
  • the silicon-oxygen material can include at least two kinds of simple silicon, silicon dioxide, and silicon oxide.
  • lithium silicate includes Li 2 SiO 3 , Li 2 Si 2 O 5 , Li 4 SiO 4 , Li 2 Si 3 O 7 , Li 8 SiO 6 , Li 6 Si 2 O 7 , Li At least one of 4 Si 2 O 7 , Li 2 Si 4 O 7 and LiSiO 3 .
  • the lithium metal is embedded in the silicon-oxygen framework, showing a lithium silicate framework structure.
  • lithium silicate includes Li 2 O ⁇ mSiO 2 , where m satisfies 0 ⁇ m ⁇ 2, for example, m can be 0.1, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4, 1.5, 1.6, 1.8 or 2.
  • the water-insoluble silicate includes zA 2 O ⁇ MO y ⁇ xSiO 2 , wherein M includes Mg, Al, Ca, Ge, Cr, V, Ti, Sc, Co, Ni, At least one of Cu, Sr, Zn, Zr, Fe, and Mn, A includes at least one of Li, Na, and K, 0.2 ⁇ x ⁇ 10.0, 1.0 ⁇ y ⁇ 3.0, 0 ⁇ z ⁇ 5.0. It should be noted that metal A and/or metal M are embedded in the silicon-oxygen framework to form a framework structure of water-insoluble silicate.
  • the water-insoluble silicate further includes A 2 O ⁇ nSiO 2 , wherein A includes at least one of Li, Na, and K, and 1 ⁇ n ⁇ 10.
  • the water-insoluble silicate may include but not limited to Mg 2 SiO 4 , Al 2 SiO 5 , CaSiO 3 , LiAlSiO 4 , LiAlSiO, LiAlSi 2 O 6 , LiAlSi 3 O 8 , Li 2 MgSiO 4 , MgSiO 3 , or Li 2 CaSiO 4 .
  • the optional work function range of the water-insoluble silicate is 2.5eV ⁇ 7.0eV, optionally 4.50eV ⁇ 6.5eV, which can be guaranteed On the basis of processing performance, it is beneficial to improve the electron transfer efficiency and greatly improve the conductivity of the powder. It can be understood that the appropriate work function range can make the electron transfer efficiency between heterojunctions higher.
  • the skeleton of the water-insoluble silicate is used as the outer skeleton and is in direct contact with the conductive carbon layer, and its work function needs to be higher than that of the carbon layer.
  • the work function is lower than that of lithium silicate, which is more conducive to the transfer of electrons from the outer layer to the inner layer and improves the conductivity.
  • the water-insoluble silicate is located in the depth region of 20nm to 50nm on the surface of the active material, such as 25nm to 45nm, 28nm to 38nm or 30nm to 35nm, such as 20nm, 24nm, 26nm, 28nm, 30nm , 34nm, 36nm, 38nm, 40nm, 44nm, 46nm, 48nm, 50nm, or the interval value between any two endpoints above. That is, the water-insoluble silicate is located in the radial direction from the surface of the active material to a depth of, for example, 20nm to 50nm.
  • the skeleton of the water-insoluble silicate is distributed in the non-water-soluble silicate.
  • the surface layer structure composed of silicon-oxygen materials on the skeleton of the water-soluble silicate can prevent the electrolyte from entering the interior of the active material, prevent water from contacting with the strong alkali lithium silicate, and effectively inhibit the hydrolysis of lithium silicate.
  • the skeleton of the water-insoluble silicate is connected with the lithium silicate skeleton to form a heterojunction structure.
  • the silicon-oxygen material is embedded in the skeleton structure, and the skeleton of the water-insoluble silicate and the lithium silicate skeleton are connected in series through the silicon-oxygen material, so that the two skeletons are connected to form an obvious heterojunction.
  • This heterojunction is composed of lithium silicate and water-insoluble silicate, both of which are grown through the common SiO2 skeleton reaction, so the interface is closely connected and continuous without forming a vacuum section, which is beneficial Electron transfer between heterojunction materials.
  • this heterojunction can promote the transfer of electrons in the active material and improve the conductivity.
  • the conductivity of the active material can be effectively improved, the first effect of the material can be improved, hydrolysis can be inhibited, and pH can be controlled.
  • the intensity of the diffraction characteristic peak of lithium silicate is I A
  • the intensity of the diffraction characteristic peak of water-insoluble silicate is I B
  • 0.03 ⁇ IB /IA ⁇ 0.20 the intensity of the diffraction characteristic peak of water-insoluble silicate
  • the electron transport ability can be maximized by means of the heterojunction, and the electron conductivity can reach more than 15 S/cm, which is conducive to the exertion of the rate performance of the material.
  • 0.12 ⁇ IB / IA ⁇ 0.18, so as to ensure the high conductivity of the silicon-based material under the condition of ensuring the processability.
  • the intensity of the diffraction characteristic peak of the water-insoluble silicate is I c
  • the intensity of the diffraction characteristic peak of the lithium silicate inside the active material is I
  • the intensity of the diffraction characteristic peak of the treated water-insoluble silicate is ID , and 0.03 ⁇ (I C -ID )/2I ⁇ 0.2 .
  • the acid solution is sulfuric acid, hydrochloric acid, nitric acid, aqua regia, etc.
  • the water-insoluble silicate is water-insoluble lithium silicate
  • the ratio of (I C -ID )/2I it is also possible to achieve the strongest electron transport ability by virtue of the heterojunction, thereby effectively utilizing the material Excellent rate performance ensures high conductivity of silicon-based materials.
  • the mass content of the Li element in the water-insoluble silicate on the surface of the active material is W 1 %, and the Li element content in the lithium silicate inside the active material is W 2 %, W 2 >W 1 ⁇ 0. That is, the Li element concentration on the surface of the active material is lower than the Li element concentration inside the active material.
  • Lithium silicate is mainly located inside the active material, while the non-water-soluble silicate is located on the outer layer of the active material.
  • the silicon-oxygen material covered by the skeleton of the non-water-soluble silicate can prevent the electrolyte from entering the interior of the active material and prevent water from entering the active material.
  • Contact with strong alkali lithium silicate can effectively inhibit the hydrolysis of lithium silicate, achieve pH regulation, and inhibit gas production.
  • the negative electrode material further includes a carbon layer formed on the surface of the active material. It can be understood that the skeleton of the water-insoluble silicate on the surface of the active material and the silicon-oxygen material embedded therein can directly contact the carbon layer, which can ensure the stability of the conductive channel and the lithium ion transport channel inside the particle.
  • the material of the carbon layer is selected from at least one of hard carbon, soft carbon, carbon nanotubes, carbon nanofibers, graphite and graphene.
  • the average thickness of the carbon layer is 30nm-500nm, optionally, the thickness of the carbon layer can be, for example, 60nm-450nm, 120nm-350nm or 220nm-320nm, such as 30nm, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, or an interval value between any two endpoints above, the thickness of the carbon layer is not limited to the listed values, and other unlisted values within the range of values are also applicable.
  • the thickness of the carbon layer in the present disclosure is within the above range, which is conducive to improving the transmission efficiency of lithium ions, and at the same time, it is beneficial to charge and discharge the material at a large rate, effectively ensuring the comprehensive performance of the negative electrode material; at the same time ensuring the conductivity of the negative electrode material and possessing the volume of the material Swell inhibition, maintain the long-term cycle performance of the negative electrode material.
  • the mass percentage content of carbon in the negative electrode material is 1.5wt% to 10wt%, optionally, it can be, for example, 2.0wt% to 8.0wt%, 4.0wt% ⁇ 7.0wt% or 5.0wt% ⁇ 6.0wt%, such as 1.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5 wt%, 9wt% or 10wt%, etc., or an interval value between any two endpoints above, but the mass percentage of carbon is not limited to the listed values, and other unlisted values within this range are also applicable.
  • the mass percentage content of lithium in the negative electrode material is 3wt% ⁇ 15wt%, alternatively, the mass percentage content of lithium can be for example 4wt% ⁇ 14wt%, 6wt% ⁇ 12wt% or 8wt% ⁇ 10wt%, such as 3wt%, 3.5wt%, 4.5wt%, 5.5wt%, 8wt%, 9.5wt%, 10.5wt%, 12.1wt%, 12.9wt% or 15wt%, etc., or the interval value between any two endpoints above, but lithium The mass percentage of is not limited to the listed numerical values, and other unlisted numerical values within the numerical range are also applicable.
  • the lithium content of the negative electrode material is within the above range, ensuring that most of the lithium source enters the interior of the silicon-oxygen material to form a lithium silicate skeleton (that is, lithium silicate 120), which improves the high initial Coulombic efficiency of the negative electrode material.
  • the lithium silicate selected above can control the amount of lithium in the surface layer, reduce the loss of lithium after surface treatment, improve the utilization rate, and ensure that the skeleton of silicate in the surface layer of the active material can be formed during lithium doping (that is, non- Water-soluble silicate 140), and has the characteristics of water insolubility, thereby effectively hindering the contact between water and strong alkali lithium silicate (that is, lithium silicate 120), effectively inhibiting the hydrolysis of lithium silicate, exerting pH control, and inhibiting the effect of gas production effect.
  • the specific surface area of the negative electrode material is 1.0m 2 /g-12.0m 2 /g; it can be, for example, 2.0m 2 /g-10.0m 2 /g, 3.5m 2 /g-6.0m 2 /g or 4.0m 2 /g ⁇ 5.5m 2 /g, such as 1.0m 2 /g, 1.50m 2 /g, 2.00m 2 /g, 3.00m 2 /g, 4.00m 2 /g, 5.0m 2 /g, 7.0m 2 /g, 9.0m 2 /g, 10.0m 2 /g or 12.0m 2 /g, etc., or the interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range Numerical values also apply.
  • the specific surface area of the negative electrode material is within the above range, which ensures the processing performance of the material, is conducive to improving the first-time efficiency of the lithium battery made of the negative electrode material, and is beneficial to improving the cycle performance of the
  • the average particle size of the negative electrode material is 3.0 ⁇ m to 12.0 ⁇ m, which can be, for example, 4.0 ⁇ m to 11.0 ⁇ m, 5.0 ⁇ m to 10.0 ⁇ m or 6.0 ⁇ m to 8.0 ⁇ m, such as 3.0 ⁇ m, 4.0 ⁇ m, 6.5 ⁇ m, 7.0 ⁇ m, 8.2 ⁇ m, 9.5 ⁇ m, 10.0 ⁇ m or 12.0 ⁇ m, etc., or the interval value between any two endpoints above.
  • the average particle size of the negative electrode material is controlled within the above range, which is beneficial to the improvement of the cycle performance of the negative electrode material.
  • the average particle size of the negative electrode material is 4.5 ⁇ m ⁇ 9.0 ⁇ m.
  • the tap density of the negative electrode material is 0.6g/cm 3 to 1.2g/cm 3 ; g/cm 3 or 0.9g/cm 3 ⁇ 1.0g/cm 3 , such as 0.6g/cm 3 , 0.7g/cm 3 , 0.75g/cm 3 , 0.8g/cm 3 , 0.85g/cm 3 , 0.9g /cm 3 , 0.95g/cm 3 , 1.0g/cm 3 , 1.1g/cm 3 or 1.2g/cm 3 , etc., or the interval value between any two endpoints above, but not limited to the listed
  • the numerical value of , other unlisted numerical values in this numerical range are also applicable. If the tap density of the negative electrode material is within the above range, it is beneficial to improve the energy density of the lithium battery made of the negative electrode material.
  • the pH value of the negative electrode material is 8.5-12.0, which can be, for example, 8.6-11.0, 9.0-10.5 or 9.5-10.0, such as 8.5, 8.8, 8.9, 9.2, 9.5, 9.8, 10.0, 10.3, 10.5, 10.8, 11.0, 12.0, etc. , or an interval value between any two of the above endpoints. It can be understood that filling the carbon material with lithium-containing compounds can effectively reduce the alkalinity of the material, improve the processing performance of the material in water system, and improve the first effect of the negative electrode material.
  • the lithium element content in the water-insoluble silicate of the negative electrode material is pm, and the total lithium element content of the negative electrode material is p Li , where 0.01 ⁇ pm/p Li ⁇ 0.6 is satisfied. It is found in the present disclosure that the content of lithium element in the negative electrode material is distributed within the above range, which can further ensure the formation of a stable water-insoluble silicate skeleton (ie, water-insoluble silicate 140) on the surface of the active material, thereby effectively preventing water and strong Alkali lithium silicate (that is, lithium silicate 120) contact can effectively inhibit the hydrolysis of lithium silicate, achieve pH regulation, and inhibit gas production.
  • a stable water-insoluble silicate skeleton ie, water-insoluble silicate 140
  • Alkali lithium silicate that is, lithium silicate 120
  • the negative electrode material is a silicon-oxygen composite material.
  • One embodiment of the present disclosure provides a method for preparing an anode material, comprising the following steps:
  • the negative electrode material includes an active material, and the active material includes a skeleton structure running through the active material and a silicon-oxygen material distributed on the skeleton structure; the skeleton structure includes a lithium silicate skeleton inside the active material and a water-insoluble silicate on the surface of the active material The skeleton of the water-insoluble silicate is connected with the lithium silicate skeleton.
  • the substance containing metal M reacts with the etched silicon-oxygen material in the solid state, so that the surface of the etched silicon-oxygen material forms Water-insoluble silicate can effectively isolate soluble strong alkaline substances such as lithium silicate from dissolving in the slurry, resulting in pH out of control, inhibiting the gas production of the slurry, and preventing the loss of active silicon-oxygen materials and active lithium, and improving the quality of materials.
  • lithium silicate and water-insoluble silicate are silicates of different crystal forms grown on the same silicon-oxygen skeleton, which can form a tight heterojunction interface without forming a vacuum section, which is conducive to heterogeneity
  • the electron transfer between the junction materials improves the ionic conductivity of the material, which is conducive to the exertion of the rate performance of the material, and the whole preparation process is simple, which is conducive to mass production and reduces costs.
  • the preparation method also includes:
  • carbon coating is carried out on the silicon-oxygen material, because the carbon coating layer is relatively loose and there are a large number of micropores, and the subsequent lithium source can penetrate through the carbon coating through the micropores of the carbon coating layer. layer and react on the surface of the silicon-oxygen material, and in the final negative electrode material obtained, the carbon coating layer is still located in the outermost layer.
  • carbon coating includes carbon coating in gas phase and/or carbon coating in solid phase.
  • the temperature of the silicon-oxygen material is raised to 600° C.-1000° C. under a protective atmosphere, and an organic carbon source gas is introduced, kept for 0.5-10 hours and then cooled.
  • the organic carbon source gas includes hydrocarbons.
  • the source of organic carbon includes hydrocarbons.
  • hydrocarbons include alkanes, alkenes, alkynes, aromatics.
  • the hydrocarbons are hydrocarbons gasifiable at 600°C to 1000°C.
  • the hydrocarbons include at least one of methane, ethylene, acetylene, and benzene.
  • the hydrocarbons include at least one of organic carbon sources such as methane, ethane, propane, ethylene, propylene, acetylene, benzene, or toluene.
  • the carbon source includes at least one of hard carbon, soft carbon, carbon nanotubes, carbon nanofibers, graphite, graphene, pitch, and organic-inorganic hybrid carbon materials.
  • the preparation method also includes:
  • a prelithiated silicon oxide material obtained by reacting a silicon oxide material with a lithium source
  • the carbon-coated silicon-oxygen material is reacted with a lithium source to obtain a pre-lithiated carbon-coated silicon-oxygen material.
  • the silicon-oxygen material is SiO n , wherein, 0.5 ⁇ n ⁇ 1.5, SiO n can be SiO 0.5 , SiO 0.6 , SiO 0.7 , SiO 0.8 , SiO 0.9 , SiO, SiO 1.1 , SiO 1.2 or SiO 1.5 etc., for example.
  • the silicon-oxygen material is SiO.
  • the average particle size (D 50 ) of the silicon-oxygen material is 2.0 ⁇ m-15.0 ⁇ m; it can be, for example, 3.0 ⁇ m-13.0 ⁇ m, 6.0 ⁇ m-11.0 ⁇ m or 7.0 ⁇ m-10.0 ⁇ m, such as 2.0 ⁇ m, 3.5 ⁇ m, 4.0 ⁇ m, 4.5 ⁇ m, 5.0 ⁇ m, 5.5 ⁇ m, 6.0 ⁇ m, 7.5 ⁇ m, 9.0 ⁇ m, 10.5 ⁇ m, 12 ⁇ m or 15.0 ⁇ m, etc., or an interval value between any two endpoints above.
  • the average particle size of the silicon-oxygen material in the present disclosure is within the above range, which can further ensure the structural stability, thermal stability and long-term cycle stability of the negative electrode material.
  • the average particle size (D 50 ) of the carbon-coated silicon oxide material is 2.0 ⁇ m-15.0 ⁇ m; it may be, for example, 3.0 ⁇ m-13.0 ⁇ m, 6.0 ⁇ m-11.0 ⁇ m or 7.0 ⁇ m-10.0 ⁇ m, such as 2.0 ⁇ m, 3.5 ⁇ m, 4.0 ⁇ m, 4.5 ⁇ m, 5.0 ⁇ m, 5.5 ⁇ m, 6.0 ⁇ m, 7.5 ⁇ m, 9.0 ⁇ m, 10.5 ⁇ m, 12 ⁇ m or 15.0 ⁇ m, etc., or the interval value between any two of the above endpoint values, but It is not limited to the listed values, and other unlisted values within the range of values are also applicable.
  • the carbon-coated silicon-oxygen material or the particle size of the silicon-oxygen material is controlled within the above range, which can avoid the problem of cycle stability caused by the type and uneven distribution of lithiated silicate products, and is conducive to improving the negative electrode material. Structural stability, thermal stability and long-term cycle stability.
  • the thickness of the carbon layer on the surface of the carbon-coated silicon-oxygen material is 30nm-500nm, which can be, for example, 50nm-550nm, 90nm-500nm, 160nm-400nm or 220nm-300nm, such as 30nm, 50nm, 60nm, 70nm, 80nm , 90nm, 100nm, 150nm, 200nm, 300nm, 400nm or 500nm, or the interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range are also applicable.
  • the coating layer is too thick, the lithium ion transmission efficiency will decrease, which is not conducive to the high-rate charge and discharge of the material, and the overall performance of the negative electrode material will be reduced. If the coating layer is too thin, it is not conducive to increasing the conductivity of the negative electrode material and affecting the volume of the material. The swelling inhibition performance is weak, resulting in poor long-cycle performance.
  • the lithium source includes simple lithium, lithium-containing compounds or mixtures thereof.
  • the lithium source includes at least one of lithium hydride, alkyllithium, metal lithium, lithium aluminum hydride, lithium amide and lithium borohydride.
  • the lithium source also includes lithium-containing oxides, lithium-containing hydrides, and the like.
  • the carbon-coated silicon-oxygen material or the reaction temperature of the silicon-oxygen material and the lithium source is 150°C to 300°C, for example, 180°C to 280°C, 200°C to 260°C or 210°C to 240°C, such as 150°C °C, 170°C, 180°C, 200°C, 220°C, 250°C, 280°C or 300°C, etc., or an interval value between any two endpoints above.
  • the reaction time is 2.0h ⁇ 6.0h, which can be 2.0h, 2.5h, 3.0h, 3.5h, 4.0h, 4.5h, 5.0h, 5.5h or 6.0h, etc., or the interval between any two endpoints above value.
  • At least part of the lithium source enters the interior of the silicon-oxygen material particles to form a Li-SiO material, and most of the lithium source is deposited on the surface of the silicon-oxygen material and undergoes a reduction reaction with the silicon-oxygen material to generate lithium oxide or hydrogen.
  • Lithium oxide, these lithium oxides or lithium hydroxides are embedded in the pores of the carbon coating layer on the surface of the silicon-oxygen material.
  • the mass ratio of the carbon-coated silicon-oxygen material SiO n to the lithium source is 1:(0.01-0.20), optionally, for example, 1:(0.02-0.18), 1:( 0.04 ⁇ 0.16) or 1:(0.08 ⁇ 0.12), such as 1:0.01, 1:0.03, 1:0.05, 1:0.1, 1:0.15, 1:0.2, etc., or the interval between any two endpoints above Values, but not limited to the listed values, other unlisted values within the value range are also applicable.
  • the mass percent content of lithium in the pre-lithiated carbon-coated silicon-oxygen material is 3 wt % to 20 wt %.
  • the present disclosure found that the lithium content in the pre-lithiated carbon-coated silicon-oxygen material in the present disclosure is within the above range, which can ensure the effective generation of water-insoluble silicate with high stability, thereby preventing the electrolyte from entering the active material. Effectively suppress gas production.
  • the mass percent content of lithium in the pre-lithiated carbon-coated silicon-oxygen material can be, for example, 4wt%-18wt%, 6wt%-16wt%, or 9wt%-14wt%, such as 3wt%, 5wt%, 8wt% %, 10wt%, 12wt%, 15wt%, 18wt% or 20wt%, etc., or the interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range of values are the same Be applicable.
  • the pre-lithiated silicon oxide material or the pre-lithiated carbon-coated silicon oxide material may be surface-etched by pickling.
  • the acid solution used in the surface etching treatment has the following characteristics: when performing the surface etching treatment on the pre-lithiated silicon-oxygen material, the pH of the reaction system of the surface etching is maintained ⁇ 7.
  • the acid solution used in the surface etching treatment includes but is not limited to hydrochloric acid, acetic acid, nitric acid, citric acid, oxalic acid, sulfuric acid, formic acid, phenol, phosphoric acid, hydrogen phosphate, hydroiodic acid, hydrogen bromide acid, ethylenediaminetetraacetic acid, glycolic acid, gluconic acid, succinic acid at least one.
  • the time for the surface etching treatment is 0.5-10.0 hours.
  • the surface layer of the silicon-oxygen material is mainly silicon-oxygen material and contains disproportionated silicon dioxide.
  • the silicon dioxide skeleton exposed on the surface of the silicon-oxygen material after the surface etching treatment reacts with the metal M-containing substance to form a water-insoluble silicate.
  • the metal M-containing substance includes M metal simple substance and/or a metal M-containing compound, and the metal M-containing compound includes metal M carbonate, metal M oxide, and metal M hydrogen At least one of oxides and soluble silicates of metal M, wherein M is selected from at least one of Mg, Al, Ca, Ge, Cr, Pb, Sr, Zn, Zr, Fe and Mn.
  • the material containing metal M can be an oxide of M, such as magnesium oxide, calcium oxide, aluminum oxide, etc.
  • the material containing metal M can be a carbonate of metal M, such as magnesium carbonate, calcium carbonate, aluminum carbonate .
  • a simple substance containing metal M wherein M is selected from at least one of Mg, Al, Ca, Ge, Cr, Pb, Sr, Zn, Zr, Fe and Mn.
  • the aforementioned metal M and metal A are respectively selected from metal elements with an electronegativity of 1.0-1.9.
  • the substance containing metal M is metal M oxide.
  • the substance containing metal A includes: at least one of metal A simple substance, metal A carbonate, metal A oxide, and metal A hydroxide, wherein A includes Li, At least one of Na and K.
  • the metal A is at least one selected from Li, Na, and K.
  • the metal A-containing compound includes at least one of metal A carbonate, metal A oxide, metal A hydroxide, and metal A soluble silicate, wherein, Exemplarily, the compound containing metal A can be an oxide of A, such as lithium oxide, potassium oxide, sodium oxide, etc.; the compound containing metal A can be a carbonate of metal A, such as lithium carbonate, potassium carbonate, sodium carbonate , wherein metal salts with strong alkalinity (such as pH>10) such as lithium carbonate, sodium carbonate, and potassium carbonate can be used in doping, and cannot be used alone.
  • metal salts with strong alkalinity such as pH>10
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the metal M-containing compound is 1: (0.01-0.1), optionally 1: (0.075 ⁇ 0.1).
  • the disclosure found that when the mass ratio is too high, excessive insoluble inactive MO xSiO 2 is generated on the surface, 0.2 ⁇ x ⁇ 10.0, which will lead to a decrease in the reversible capacity of the powder and a decrease in electrical conductivity; when the mass ratio is too low, it means that the metal M If the content of the substance is too small, the substance containing metal M cannot fully react with the silicon-oxygen material, which is not conducive to the formation of a water-insoluble silicate skeleton on the surface of the silicon-oxygen material, resulting in the electrolyte easily passing through the surface of the negative electrode material and the particle interior. The reaction of lithium silicate is not conducive to inhibiting the alkalinity of the material, which makes the negative electrode material produce serious gas during the processing process, and the first efficiency and cycle stability of the battery decrease.
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the simple substance or compound containing metal A is 1: (0.01-0.1), and it is also found in the present disclosure that the insoluble and non-active A 2 O ⁇ nSiO 2 , 1 ⁇ n ⁇ 10, in the above ratio range of the present disclosure, it can ensure the high inverse capacity and high conductivity of the powder, so that the compound of metal A can fully react with the silicon-oxygen material, which is beneficial to the silicon-oxygen
  • the surface layer of the material forms a skeleton of water-insoluble silicate to avoid the reaction between the electrolyte and the lithium silicate inside the particles, thereby effectively inhibiting the alkalinity of the material and preventing the negative electrode material from producing gas during processing, thereby further improving the first efficiency and cycle of the battery stability.
  • the mass ratio of the silicon-oxygen material after surface etching treatment to the substance containing metal M may be, for example, 1:(0.020-0.095), 1:(0.040-0.090), 1:(0.060-0.085) or 1 : (0.078 ⁇ 0.082), such as 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.075, 1:0.081, 1:0.083, 1: 0.085, 1: 0.087, 1: 0.091, 1: 0.093, 1: 0.095 or 1: 0.1, etc., or the interval value between any two endpoints above, but not limited to the listed values, within the value range Other values not listed also apply.
  • the mass ratio of the silicon-oxygen material after the surface etching treatment to the simple substance or compound containing metal A can be, for example, 1:(0.020-0.095), 1:(0.040-0.090), 1:(0.060-0.085) Or 1: (0.078 ⁇ 0.082), such as 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.075, 1:0.081, 1:0.083, 1:0.085, 1:0.087, 1:0.091, 1:0.093, 1:0.095 or 1:0.1, etc., or the interval value between any two endpoints above, but not limited to the listed values, the value Other unrecited values within the range also apply.
  • the mixing method includes at least one of mechanical stirring, ultrasonic dispersion, and grinding dispersion.
  • the mixing method is not limited to the above-mentioned method, and any method that can uniformly mix the pre-lithiated silicon-oxygen material and the material containing the metal M is fine.
  • the mixing method is ball milling, and the ball milling time is 3h-24h; it can be, for example, 6h-21h, 9h-17h or 11h-15h, such as 3h, 4h, 5h, 6h, 8h, 12h, 16h, 18h, 20h Or 24h, etc., or the interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range of values are also applicable. It can be understood that sufficient ball milling can make the metal M-containing substance evenly adhere to the surface of the silicon-oxygen material after surface etching treatment or the surface of carbon-coated silicon-oxygen material after surface etching treatment.
  • the protective atmosphere includes at least one of nitrogen, helium, neon, argon, krypton and xenon.
  • the solid-phase thermal reaction is a calcination process, and the calcination can be performed in a calcination furnace so that the calcination can be fully performed.
  • the temperature of the solid phase thermal reaction is 600°C to 1200°C, for example, 640°C to 1160°C, 720°C to 920°C or 780°C to 820°C, such as 600°C, 700°C, 750°C, 800°C . Values not listed are also applicable, and 750°C to 1150°C is optional. It can be understood that when the reaction temperature is too high, the reaction will be violent, and the silicon grains will grow rapidly, which will affect the cycle performance of the material; Salt skeleton cannot be generated.
  • the solid-phase thermal reaction time is 3h-12h, for example, it can be 5h-11h, 6h-9h or 7h-8h, such as 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h etc., or an interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range are also applicable.
  • the skeleton of water-insoluble silicate can be formed on the surface layer of the silicon-oxygen material after surface etching treatment by sufficient calcination.
  • the heating rate of the solid-phase thermal reaction is 1°C/min to 5°C/min, for example, it can be 1°C/min, 2°C/min, 3°C/min, 4°C/min or 5°C/min, etc. , or an interval value between any two endpoints above, but not limited to the listed values, other unlisted values within the range are also applicable.
  • the substance containing metal M reacts with the silicon dioxide skeleton exposed by the disproportionation on the surface of the silicon-oxygen material after the surface etching treatment and the strong alkaline lithium silicate to form a water-insoluble silicate.
  • the skeleton prevents the electrolyte from easily passing through the surface of the negative electrode material and reacting with the lithium silicate inside the particle, which can reduce the pH value of the material, thereby affecting the pH value of the entire negative electrode slurry, improving the processing stability of the pre-lithium material, and making the negative electrode The first effect of the material is improved.
  • step S20 the method further includes:
  • the average particle size of the negative electrode material is 1 ⁇ m to 10 ⁇ m, such as 2.5 ⁇ m to 9.5 ⁇ m, 3.5 ⁇ m to 7 ⁇ m, or 4.5 ⁇ m to 6.5 ⁇ m, such as 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m or 10 ⁇ m, etc., or the interval value between any two endpoint values mentioned above.
  • the average particle size of the negative electrode material is controlled within the above range, which is beneficial to the improvement of the cycle performance of the negative electrode material.
  • the average particle diameter of the negative electrode material is 4 ⁇ m ⁇ 7 ⁇ m.
  • sieving includes at least one of crushing, ball milling, screening, or classifying.
  • the negative electrode material prepared by the above preparation method can hinder the reaction between the strong alkaline material and the solvent, suppress the gas production, and reduce the impact on the material at the same time.
  • the influence of capacity first effect realizes the control of the pH value of the negative electrode slurry made of this material.
  • the active silicon-oxygen material can remain embedded in the silicate skeleton and the lithium silicate skeleton, and the formed skeleton structure can stabilize and play an expansion buffer role, so that nano-silicon crystal grains are embedded in the entire particle system, making the silicon-oxygen material It can maintain good contact with the conductive carbon layer, realize the improvement of conductivity, reduce the interface impedance, and ensure the stability of the conductive channel and lithium ion transmission channel inside the particle.
  • an embodiment of the present disclosure provides a method for preparing an anode material, comprising the following steps:
  • the silicon-oxygen material after the surface etching treatment can also be additionally mixed with a substance containing metal A, and metal A includes alkali metal elements.
  • metal A includes at least one of Li, Na and K kind.
  • the present disclosure provides a lithium ion battery, which includes the negative electrode material of the first aspect above or the negative electrode material prepared by the preparation method of the second aspect above.
  • the silicon-oxygen material is embedded in the skeleton structure, and the skeleton of the water-insoluble silicate on the outer layer is connected to the lithium silicate skeleton inside, which is beneficial to the electrochemical performance of the active material and rapidly conducts electrons.
  • the transfer and deintercalation of lithium is beneficial to reduce the internal resistance of the material and improve the transfer capacity of lithium ions.
  • the encapsulation of the silicon-oxygen material by the skeleton of the water-insoluble silicate located on the outer layer can effectively prevent the contact of water with the strong alkaline lithium silicate and inhibit the hydrolysis of lithium silicate, thereby effectively improving the gas production of the material and realizing the protection of the material. pH control to improve processing performance.
  • the lithium silicate in the inner layer and the water-insoluble silicate in the outer layer are closely connected through silicon and silicon-oxygen materials.
  • the difference in work function of the two silicate materials leads to the formation of a heterojunction interface between the two, which can Improve electron transfer efficiency, thereby increasing lithium intercalation depth, improving capacity and cycle performance.
  • the pre-lithiated silicon-oxygen material is subjected to surface etching treatment, and the material containing metal M is reacted with the silicon-oxygen material after etching in solid state, so that the etched
  • the surface of the silicon oxide material after etching forms a non-water-soluble silicate, which can effectively isolate soluble strong alkaline substances such as lithium silicate from dissolving in the slurry, resulting in pH out of control, inhibiting the gas production of the slurry, and preventing active silicon oxide
  • the loss of materials and active lithium improves the first-effect capacity of materials; lithium silicate and water-insoluble silicate are silicates of different crystal forms grown on the same silicon-oxygen skeleton, which can form a tight heterojunction interface, without A vacuum section will be formed, which is conducive to electron transfer between heterojunction materials, improves the ionic conductivity of the material, and is conducive to the exertion of the rate performance of the material, and
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton i.e.
  • lithium silicate 120) in this embodiment is Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 4 SiO 4 , and the surface layer of the active material (i.e. water-insoluble silicate 140) is Mg 2 SiO 4 and Li 2 MgSiO 4 .
  • the average particle diameter (D 50 ) of the negative electrode material is 5.0 ⁇ m, the tap density is 0.98g/cm 3 , the specific surface area is 2.54m 2 /g, the mass percentage content of lithium in the negative electrode material is 9.5wt%, the carbon layer The thickness is 183nm.
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton (i.e. lithium silicate 120) in this embodiment is Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 4 SiO 4 , and the surface layer of the active material (i.e. water-insoluble silicate 140) is Li 2 MgSiO 4 .
  • the negative electrode material prepared in this example has an average particle size (D 50 ) of 5.0 ⁇ m, a tap density of 0.98 g/cm 3 , a specific surface area of 2.54 m 2 /g, and a mass percentage content of lithium in the negative electrode material of 9.5 wt. %, the thickness of the carbon layer is 183nm.
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton i.e.
  • lithium silicate 120) in this embodiment is Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 4 SiO 4 , and the surface layer of the active material (i.e. water-insoluble silicate 140) is Mg 2 SiO 4.
  • the negative electrode material prepared in this example has an average particle size (D 50 ) of 5.0 ⁇ m, a tap density of 0.98 g/cm 3 , a specific surface area of 2.54 m 2 /g, and a mass percentage content of lithium in the negative electrode material of 9.5 wt. %, the thickness of the carbon layer is 183nm.
  • the XRD diffraction pattern of the negative electrode material prepared in this embodiment is shown in FIG. 6 .
  • Step (1) is close to Example 1, except that lithium content is 11wt%;
  • Step (2) is similar to Example 1, except that the pre-lithiated material is soaked in 12wt% acetic acid solution for 1.2h;
  • Step (3) Add Al 2 O 3 (7.5g) and surface-etched pre-lithium silicon oxide (100g) into a ball mill. After ball milling for 10 hours, transfer to a graphite crucible and treat at 850°C under a protective atmosphere After 10 hours, the negative electrode material was obtained by crushing, sieving and classifying.
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton i.e.
  • lithium silicate 120) in this embodiment is Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 4 SiO 4 , and the surface layer of the active material (i.e. water-insoluble silicate 140) is Al 2 SiO 5.
  • the average particle size (D 50 ) of the negative electrode material prepared in this example is 5.0 ⁇ m, the tap density is 0.98 g/cm 3 , the specific surface area is 2.77 m 2 /g, and the mass percentage content of lithium in the negative electrode material is 9.6 wt %, the thickness of the carbon layer is 177nm.
  • Step (1) is close to Example 1, except that lithium content is 11wt%;
  • Step (2) is similar to Example 1, except that the pre-lithiated material is soaked in 1wt% nitric acid solution for 0.5h;
  • Step (3) Add Na 2 CO 3 (8g) and pre-lithium silicon oxide (100g) after surface etching into a ball mill, after ball milling for 10h, transfer to a graphite crucible, and treat at 850°C for 10h under a protective atmosphere Afterwards, the negative electrode material is obtained by crushing, sieving and classifying.
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton ie lithium silicate 120
  • the active material surface layer ie water-insoluble silicate 140
  • the average particle size (D 50 ) of the negative electrode material prepared in this example is 5.0 ⁇ m, the tap density is 1.00 g/cm 3 , the specific surface area is 2.79 m 2 /g, and the mass percentage content of lithium in the negative electrode material is 10.0 wt %, the thickness of the carbon layer is 193nm.
  • Step (1) is similar to Example 1, except that the carbon-coated silicon-oxygen material is reacted with silicon-oxygen material SiO 0.75 /C with a silicon content of 65% to obtain a pre-lithiated carbon-coated silicon-oxygen material Li ⁇ SiO 0.75 //C, wherein the lithium content is 10wt%;
  • the structural representation of the negative electrode material prepared in the present embodiment is with reference to Fig. 3, and it comprises active material 100 and the carbon layer (that is cladding layer 200) that is formed on the surface of active material, and active material 100 comprises framework structure and the silicon embedded on framework structure Oxygen material;
  • the skeleton structure includes a lithium silicate skeleton (i.e. lithium silicate 120) inside the active material and a magnesium silicate skeleton (i.e. water-insoluble silicate 140) on the surface of the active material, a magnesium silicate skeleton (i.e. water-insoluble Lithium silicate 140) is connected to the lithium silicate skeleton.
  • the lithium silicate skeleton i.e.
  • lithium silicate 120) in this embodiment is Li 2 Si 2 O 5 , Li 2 SiO 3 , Li 4 SiO 4 , and the surface layer of the active material (i.e. water-insoluble silicate 140) is Mg 2 SiO 4 , MgSiO 3 , Li 2 MgSiO 4 .
  • the negative electrode material prepared in this example has an average particle size (D 50 ) of 5.0 ⁇ m, a tap density of 1.1 g/cm 3 , a specific surface area of 2.47 m 2 /g, and a mass percent content of lithium in the negative electrode material of 9.5 wt. %, the thickness of the carbon layer is 187nm.
  • the negative electrode material prepared in this embodiment includes a mixture of active material and magnesium oxide.
  • the negative electrode material prepared in this example has an average particle size (D 50 ) of 5.0 ⁇ m, a tap density of 0.98 g/cm 3 , a specific surface area of 2.54 m 2 /g, and a mass percentage content of lithium in the negative electrode material of 9.5 wt. %, the thickness of the carbon layer is 183nm.
  • the negative electrode material prepared in this embodiment includes a mixture of active material and magnesium oxide.
  • the negative electrode material prepared in this example has an average particle size (D 50 ) of 5.0 ⁇ m, a tap density of 0.98 g/cm 3 , a specific surface area of 2.54 m 2 /g, and a mass percentage content of lithium in the negative electrode material of 9.5 wt. %, the thickness of the carbon layer is 183nm.
  • Steps (1) to (2) are identical with embodiment 8;
  • Step (3) is close to Example 8, except that the addition of magnesium oxide is 11g
  • the negative electrode material prepared in this embodiment includes a mixture of active material and magnesium oxide.
  • the average particle size (D 50 ) of the negative electrode material prepared in this example is 5.0 ⁇ m, the tap density is 0.89 g/cm 3 , the specific surface area is 3.2 m 2 /g, and the mass percentage content of lithium in the negative electrode material is 9.2 wt %, the thickness of the carbon layer is 187nm.
  • the preparation method is similar to that of Example 1, except that in step (1), the silicon-oxygen material SiO is reacted with metal lithium to obtain a pre-lithiated carbon-coated silicon-oxygen material Li-SiO;
  • the average particle size (D 50 ) of the negative electrode material is 5.0 ⁇ m, the tap density is 0.98 g/cm 3 , the specific surface area is 3.01 m 2 /g, the mass percentage content of lithium in the negative electrode material is 10 wt%, and there is no carbon layer.
  • the preparation method is close to Example 1, except that in step (2), the immersion time in the citric acid solution is 30min;
  • the average particle diameter (D 50 ) of the negative electrode material is 5.0 ⁇ m, the tap density is 0.98g/cm 3 , the specific surface area is 2.74m 2 /g, the mass percentage content of lithium in the negative electrode material is 9.5wt%, the carbon layer The thickness is 189nm.
  • Pre-lithiated carbon-coated silicon-oxygen material SiO-Li/C is used as the negative electrode material, with an average particle size (D 50 ) of 5.14 ⁇ m, a tap density of 0.98 g/cm 3 , and a specific surface area of 3.24 m 2 /g.
  • the carbon content was 5.0 wt%.
  • MgCl 2 can form magnesium hydroxide colloids or precipitates in an alkaline environment, and evenly wrap around the periphery of the carbon-coated pre-lithium material SiO-Li/C powder.
  • the MgO part may be mixed with SiO 2 reacts with other silicic acid skeletons to form magnesium-containing silicate, and other MgO will evenly distribute and wrap the entire inner core to form a MgO coating layer and the outermost carbon coating layer to form a multi-layer coated core. shell structure.
  • the negative electrode material prepared in this comparative example has an average particle size (D 50 ) of 5.17 ⁇ m, a tap density of 0.98 g/cm 3 , a specific surface area of 3.40 m 2 /g, a porosity of 2.17 wt%, and a carbon content of 5.0 wt. %.
  • the mass ratio is mixed evenly, coated on the copper foil current collector, and dried to obtain the negative electrode sheet for use.
  • the button battery test was carried out on the obtained pole piece.
  • the battery was assembled in an argon glove box, with a lithium metal sheet as the negative electrode, the electrolyte was 1mol/LLiPF6+EC+EMC, and the separator was a polyethylene/propylene composite microporous membrane.
  • the electrochemical performance is carried out on the battery testing equipment, the battery capacity is set to the standard 480mAh/g, the charge and discharge voltage is 0.01 ⁇ 1.5V, the charge and discharge rate is 0.1C, the charge and discharge test is carried out, and the first reversible capacity and the first cycle charge capacity are obtained. and first cycle discharge capacity.
  • the first coulombic efficiency the discharge capacity of the first cycle / the charge capacity of the first cycle.
  • a Malvern Mastersizer 2000 laser particle size tester was used to test the particle size of the negative electrode material to obtain the average particle size.
  • the negative electrode material sample is heated and burned by a high-frequency furnace under oxygen-enriched conditions to oxidize carbon into carbon dioxide. After the gas is processed, it enters the corresponding absorption cell to absorb the corresponding infrared radiation and convert it into a corresponding signal by the detector. This signal is sampled by the computer, and converted into a value proportional to the carbon dioxide concentration after linear correction, and then the value of the entire analysis process is accumulated. After the analysis, the accumulated value is divided by the weight value in the computer, and then multiplied by the correction coefficient , and subtract the blank to obtain the percentage of carbon in the sample. Sample testing was performed using a high-frequency infrared carbon-sulfur analyzer (model Shanghai Dekai HCS-140).
  • the negative electrode material sample was soaked in deionized water (the ratio of material to water was 50wt%), stirred for 24 hours and left to stand until the material liquid was separated, and the supernatant was taken for ICP test to obtain the lithium content.
  • the pH value is the slurry pH value.
  • the gas production is to draw 4ml into the sealed syringe (10ml small range syringe) after the slurry mixing is completed, and observe the volume change value of the slurry gas volume in the syringe after 8 hours.
  • the test method is: the method is similar to the above method (i), the difference is that when adding HNO3 , an additional 6mL HF is added, and 4mL HNO3 Mix with 6mL HF to react.
  • the negative electrode materials provided by Examples 1 to 3 the silicon-oxygen material is embedded in the skeleton structure, and the skeleton of the water-insoluble silicate of the outer layer and the inner silicon Lithium acid skeleton connection is conducive to the electrochemical performance of active materials, rapid electron transfer and lithium deintercalation, which is conducive to reducing the internal resistance of the material and improving the lithium ion transfer capacity.
  • the encapsulation of the silicon-oxygen material by the skeleton of the water-insoluble silicate located on the outer layer can effectively prevent the contact of water with the strong alkaline lithium silicate and inhibit the hydrolysis of lithium silicate, thereby effectively improving the gas production of the material and realizing the protection of the material. pH regulation. Lithium ions can conduct through the skeleton structure and the silicon-oxygen material on the surface of the active material, which improves the ionic conductivity of the material and is conducive to the exertion of the rate performance of the material. For the performance data comparison of some examples and comparative examples, please refer to Figure 4-6 .
  • Example 1 the in-situ growth of water-insoluble silicate on the SiO 2 skeleton forms a stable heterojunction interface with lithium silicate, which improves the conductivity of the material to 40.21 S/cm.
  • Example 3 magnesium powder is used, and redox reaction occurs on the surface to form MgO and SiO 2 , which further improves the capacity and first effect, while MgO and SiO 2 react to form water-insoluble silicate (magnesium silicate), which can insulate the slurry with strong alkali silicates.
  • Mg reduces the SiO skeleton, the part of the silicon-oxygen material extending through the lithium silicate is destroyed, and a part of the surface of the material particle forms a tight water-insoluble silicate interface, so the powder conductivity of Example 3 decreases relatively. In Example 1, slightly reduced.
  • the composite negative electrode material only contains three components of Si/lithium silicate/magnesium silicate, and through the combination of the three materials, combined with the lithium content in the eluate , it can be found that a small amount of magnesium silicate is concentrated on the surface of the composite negative electrode material particles, and the new silicate interface forms a heterojunction structure, so the powder conductivity is much higher than that of lithium silicate/silicon and magnesium silicate/silicon samples (0.1- 10S/cm), thus the heterojunction structure on the surface of the composite anode material particles can be found.
  • Example 4 uses Al 2 O 3
  • Example 5 uses Na 2 CO 3 to grow in situ on silicon oxide respectively to form a stable heterojunction interface between water-insoluble silicate and lithium silicate, which also makes the material The electrochemical performance has been improved to a certain extent.
  • Example 6 By using the silicon oxide material with a silicon content of 65% and magnesium oxide, it is also possible to grow in situ on the silicon oxide to form a stable heterojunction interface with lithium silicate and obtain a high electrochemical performance anode materials.
  • the conventional pre-lithium material in Comparative Example 1 the conductivity of the material powder is low, this is because the silicon-based material and lithium silicate itself are insulators or semiconductors, and their conductivity as a battery core material is poor, so it can be found from the powder conductivity characterization , its powder conductivity is 7.21S/cm, while the powder conductivity of conventional graphite anode materials is above 250S/cm. Even if the surface is coated with conductive carbon, its conductivity is also very different from that of graphite anode materials.
  • a layer of magnesium oxide coating layer is coated on the surface of granular carbon by deposition method.
  • the magnesium oxide coating layer is deposited on the outer layer of the conductive layer, and the magnesium oxide coating layer covers the conductive carbon layer, reducing the structure of the conductive carbon layer and The contact of the conductive agent, therefore, the conductivity of the powder decreased significantly (0.37S/cm).
  • the rate capacity retention rates of the batteries made of this material at 0.5C, 1C, and 2C are respectively lower than those of Comparative Example 1 by more than 3%.
  • Examples 1-6 of the present disclosure can effectively ensure the high-efficiency reaction between the silicon-oxygen material after the surface etching treatment and the compound containing M or A when the processing temperature is kept within the scope of the present disclosure, not only The pH control of the material is realized to avoid gas production, and at the same time, the conductivity and rate performance of the powder are effectively improved, indicating that a more stable heterojunction structure is formed.
  • Example 7 because the treatment temperature was low, the lithium silicate on the surface and the SiO2 skeleton and magnesium oxide reacted slowly, causing gas production to occur, but the gas production was significantly lower than that of the comparative example, and the electrical conductivity of the powder was slightly lower than that of the comparative example. Improvement, the rate performance is lower than that of Example 1, indicating that a heterojunction structure has been formed.
  • the cycle capacity retention rate of the battery is also related to the heterojunction structure in the negative electrode material.
  • the 50-cycle capacity retention rate is above 90%, while In Comparative Example 1 showing two-stage differentiation, without a heterojunction structure, the 50-week capacity retention rate was nearly 10% lower, while in Comparative Example 2, the conductivity decreased due to the surface coating of magnesium oxide, and the capacity could not be exerted, which resulted in a low capacity retention rate of 10%. Chemical properties are reduced.
  • the range of pm/p Li is within the scope of the present disclosure, which can further ensure the high mass-charge conductivity of the material, further effectively suppress the alkalinity of the material, and avoid the production of negative electrode materials during processing. gas, thereby further improving the first efficiency and cycle stability of the battery.
  • the negative electrode material provided by the disclosure can improve processing performance, has excellent electrochemical cycle and expansion inhibition performance, can prolong the service life of lithium-ion batteries, and its preparation method is simple, low in cost, and easy to realize industrial production, so it has excellent industrial Practical performance.

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Abstract

本公开涉及负极材料及其制备方法、锂离子电池,其中,负极材料包括活性材料,该活性材料包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂的骨架及位于活性材料表层的非水溶性硅酸盐的骨架,非水溶性硅酸盐的骨架与硅酸锂的骨架连接,其中,该负极材料的XRD图谱中,硅酸锂的最强衍射特征峰的强度为IA,非水溶性硅酸盐的最强衍射特征峰的强度为IB,且0.03≤IB/IA≤0.2。本公开的负极材料及其制备方法简单、成本低、易于实现工业化生产,且制备得到的负极材料能够提升加工性能,具有优异的电化学循环及抑制膨胀性能,可延长锂离子电池的使用寿命。

Description

负极材料及其制备方法、锂离子电池
相关申请的交叉引用
本公开要求于2021年12月29日提交中国专利局的申请号为CN202111635594.X、名称为“硅氧复合负极材料及其制备方法、锂离子电池”的中国专利申请的优先权,其全部内容通过引用结合在本公开中。
技术领域
本公开涉及锂离子电池领域,涉及负极材料及其制备方法、锂离子电池。
背景技术
氧化亚硅材料是开发新一代超大容量锂离子电池中必不可少的负极材料。氧化亚硅工业界对于硅基锂离子电池的开发的研究和布局已经超过十年以上,然而以氧化亚硅为代表的硅基材料依然没有得到大规模运用。限制硅基材料应用的主要因素是硅基材料本身的天然劣势造成的。高膨胀与剧烈的体积变化,低首效,倍率等都是目前亟待解决的问题。硅基内核的金属掺杂,是提升硅基负极材料首效表现最直接的改进方案之一。通过掺杂还原性金属,形成非活性硅酸盐,从而避免在充嵌锂过程中,活性锂与氧作用形成非活性硅酸锂,提升硅氧材料首效。而在对于掺杂金属的选择,要求其具备一定的还原性,如Li、Mg等。金属锂是最佳的选择之一,作为锂离子电池的核心活性元素,硅基材料在预锂后,内部形成各相的硅酸锂等非活性材料,这些硅酸锂除了可以作为充放电膨胀过程中的缓冲区之外,其界面的高锂含量,也可以作为快离子导体,促进锂离子在内部的快速转移。无论在学术界还是工业界,预锂化工艺已经是一个公认的最有高效的提升硅基材料首效的方案之一。
但是,另一方面预锂硅基材料也有相当多的问题还亟需解决。其中最突出的问题之一就是pH失控带来的,产气问题,活性硅流失问题。硅基材料预锂后,锂进入硅基内核的同时,也会在表面形成强碱性硅酸盐,以及其他残碱等。而这种成分,在调浆时,会使浆料显强碱性。硅基材料,在强碱性环境中,会发生氧化还原反应,释放出氢气,而被氧化的活性硅会流失成为死硅,导致电池容量降低,而释放的氢气会影响浆料涂布过程中的极片质量。
因此,开发一种能够抑制产气、提升加工性能,循环性能优异的硅基材料及其制备方法仍是所属领域的技术难题。
发明内容
本公开提供一种负极材料,所述负极材料包括活性材料,所述活性材料包括贯穿所述活性材料的骨架结构及镶嵌于所述骨架结构上的硅氧材料;所述骨架结构包括位于所述活性材料内部的硅酸锂的骨架及位于所述活性材料表层的非水溶性硅酸盐的骨架,所述非水溶性硅酸盐的骨架与所述硅酸锂的骨架连接;
其中,所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
本公开还提供一种负极材料,所述负极材料包括活性材料;
所述活性材料包括硅酸锂、非水溶性硅酸盐和硅氧材料;
其中,所述非水溶性硅酸盐包覆于所述硅酸锂的表面;
所述硅酸锂和/或所述非水溶性硅酸盐中含有所述硅氧材料,
其中,所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
可选地,所述硅氧材料为SiO n,其中,0.5≤n≤1.5。
可选地,所述硅酸锂包括Li 2SiO 3、Li 2Si 2O 5、Li 4SiO 4、Li 2Si 3O 7、Li 8SiO 6、Li 6Si 2O 7、Li 4Si 2O 7、Li 2Si 4O 7和LiSiO 3中的至少一种。
可选地,所述非水溶性硅酸盐包括zA 2O·MO y·xSiO 2,其中,M包括Mg、Al、Ca、Ge、Cr、V、Ti、Sc、Co、Ni、Cu、Sr、Zn、Zr、Fe和Mn中的至少一种,A包括Li、Na、K中的至少一种,0.2≤x≤10.0,1.0≤y≤3.0,0≤z≤5.0。
可选地,所述非水溶性硅酸盐还包括A 2O·nSiO 2,其中,A包括为Li、Na、K的至少一种,1≤n≤10。
可选地,所述非水溶性硅酸盐的功函数范围为2.5eV≤η≤7.0eV。
可选地,所述非水溶性硅酸盐位于所述活性材料表面20nm~50nm的深度区域内。
可选地,所述非水溶性硅酸盐中的Li元素的质量含量为W 1%,所述硅酸锂中的Li元素含量为 W 2%,W 2>W 1≥0。
可选地,所述负极材料还包括存在于所述活性材料表面的碳层。
可选地,所述碳层的平均厚度为30nm~500nm。
可选地,所述负极材料的振实密度为0.6g/cm 3~1.20g/cm 3
可选地,所述负极材料的比表面积为1.00m 2/g~12.0m 2/g。
可选地,所述负极材料的平均粒径为3.0μm~12.0μm。
可选地,所述负极材料中的碳的质量百分比含量为1.5wt%~10.0wt%。
可选地,所述负极材料中的锂的质量百分比含量为3wt%~15wt%。
可选地,所述负极材料的pH为8.5~12.0。
可选地,所述负极材料的XRD图谱中,硅酸锂的最强衍射特征峰的强度为I A,非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.12≤I B/I A≤0.18。
可选地,所述负极材料的非水溶性硅酸盐中锂元素含量为pm,所述负极材料的总锂元素含量为p Li,其中0.01≤pm/p Li≤0.6。
本公开还提供一种负极材料的制备方法,包括以下步骤:
将预锂化的硅氧材料进行表面刻蚀处理;
将表面刻蚀处理后的硅氧材料与含金属M和/或金属A的物质混合,在保护气氛下进行固相热反应,得到所述负极材料。
可选地,所述含金属A的物质包括:金属A单质、金属A的碳酸盐、金属A的氧化物、金属A氢氧化物中的至少一种,其中,A包括Li、Na、K中的至少一种。
可选地,所述含金属M的物质包括金属M单质、金属M的碳酸盐、金属M的氧化物、金属M的氢氧化物中的至少一种,其中,M包括Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种。
可选地,所述表面刻蚀处理后的硅氧材料与所述含金属M和/或金属A的物质的质量比为1:(0.01~0.1)。
可选地,所述表面刻蚀处理后的硅氧材料与所述含金属M和/或金属A的物质的质量比为1:(0.075~0.1)。
本公开还提供一种负极材料的制备方法,包括以下步骤:
将预锂化的硅氧材料进行表面刻蚀处理;
将表面刻蚀处理后的硅氧材料与含金属M的化合物混合,在保护气氛下进行固相热反应,得到负极材料。
可选地,所述含金属M的化合物包括金属M的碳酸盐、金属M的氧化物、金属M的氢氧化物中的至少一种,其中,M包括Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种。
可选地,所述表面刻蚀处理后的硅氧材料与所述含金属M的化合物的质量比为1:(0.01~0.1)。
可选地,所述表面刻蚀处理后的硅氧材料与所述含金属M的化合物的质量比为1:(0.075~0.1)。
可选地,所述含金属M的化合物为金属M的氧化物。
可选地,所述混合方式包括机械搅拌、超声分散及研磨分散中的至少一种。
可选地,所述混合方式为球磨混合,所述球磨时间为3h~24h。
可选地,所述保护气氛的气体包括氮气、氦气、氖气、氩气、氪气和氙气中的至少一种。
可选地,所述固相热反应的温度为600℃~1200℃。
可选地,所述固相热反应的时间为3h~12h。
可选地,所述固相热反应的升温速率为1℃/min~5℃/min。
可选地,所述预锂化的硅氧材料为预锂化的碳包覆硅氧材料。
可选地,所述预锂化的碳包覆硅氧材料由碳包覆硅氧材料与锂源反应得到。
可选地,所述硅氧材料为SiO n,其中,0.5≤n≤1.5。
可选地,所述硅氧材料的平均粒径(D 50)为2.0μm-15.0μm。
可选地,所述碳包覆硅氧材料表面的碳层的厚度为30nm~500nm。
可选地,所述锂源包括锂单质或含有锂的化合物中的至少一种。
可选地,所述锂源包括氢化锂、烷基锂、金属锂、氢化铝锂、氨基锂和硼氢化锂中的至少一种。
可选地,所述碳包覆硅氧材料与所述锂源的反应温度为150℃~300℃。
可选地,所述碳包覆硅氧材料与所述锂源的反应时间为2.0h~6.0h。
可选地,所述碳包覆硅氧材料与所述锂源的质量比为1:(0.01~0.20)。
可选地,所述预锂化的碳包覆硅氧材料中的锂的质量百分比含量为3wt%~20wt%。
可选地,在将预锂化的硅氧材料进行表面刻蚀处理之前,所述方法还包括:
将硅氧材料与锂源反应得到的预锂化的硅氧材料;或
将碳包覆硅氧材料与锂源反应得到的预锂化的碳包覆硅氧材料。
可选地,所述表面刻蚀处理采用的酸溶液具有的特性为:在将所述预锂化的硅氧材料进行表面刻蚀处理时,保持所述表面刻蚀的反应体系pH<7。
可选地,所述表面刻蚀处理采用的酸溶液包括盐酸、醋酸、硝酸、柠檬酸、草酸、硫酸、甲酸、苯酚、磷酸、磷酸氢化物、氢碘酸、氢溴酸、乙二胺四乙酸、羟基乙酸、葡萄糖酸、丁二酸中的至少一种。
可选地,所述表面刻蚀处理的时间为0.5~10.0h。
本公开还提供一种锂离子电池,所述锂离子电池包含上述第一方面所述的负极材料或根据上述第一方面所述的负极材料的制备方法制得的负极材料。
附图说明
图1为本公开提供的负极材料的制备方法的工艺流程图;
图2为本公开提供的负极材料的结构示意图;
图3为本公开提供的负极材料的结构示意图;
图4为本公开实施例以及对比例制得的负极材料的容量保持率随循环周数增加的变化示意图;
图5为本公开实施例以及对比例制得的负极材料的电导率的变化示意图;
图6为本公开实施例3制得的负极材料的XRD衍射图谱;
附图标记:100-活性材料,200-包覆层,120-硅酸锂,140-非水溶性硅酸盐,160-硅氧材料。
具体实施方式
为更好地说明本公开,便于理解本公开的技术方案,下面对本公开进一步详细说明。但下述的实施例仅仅是本公开的简易例子,并不代表或限制本公开的权利保护范围,本公开保护范围以权利要求书为准。
本公开提供负极材料及其制备方法、锂离子电池,本公开的负极材料可以提升加工性能,具有优异的电化学循环及抑制膨胀性能,可延长锂离子电池的使用寿命,降低生产成本。
本公开一实施方式提供一种负极材料,负极材料包括活性材料,活性材料包括贯穿活性材料的骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂的骨架及位于活性材料表层的非水溶性硅酸盐的骨架,非水溶性硅酸盐的骨架与硅酸锂的骨架连接;其中,负极材料的XRD图谱中,硅酸锂的最强衍射特征峰的强度为I A,非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
可选地,I B/I A的范围可以为例如0.05≤I B/I A≤0.2、0.1≤I B/I A≤0.2、0.12≤I B/I A≤0.18或0.14≤I B/I A≤0.16。
如本文所用,术语“骨架”是指形成某一结构(诸如单元结构、块状结构、片状结构、层状结构、核结构、壳体结构等)的主要物质(诸如该主要物质的重量占比该结构总重量大于等于51%),换句话说,可以理解该主要物质作为支持、形成或构成某一结构的基础物质;例如“硅酸锂的骨架”可以理解为,硅酸锂是形成硅酸锂所在结构的主要成分,是支持、形成或构成硅酸锂所在结构的基础物质,硅酸锂所在结构可以在内部分散/镶嵌有其他成分(诸如本文公开的硅氧材料);例如,“非水溶性硅酸盐的骨架”可以理解为,非水溶性硅酸盐是形成非水溶性硅酸盐所在结构的主要成分,是支持、形成或构成非水溶性硅酸盐所在结构的基础物质,非水溶性硅酸盐所在结构可以在内部分散/镶嵌有其他成分(诸如本文公开的硅氧材料)。
在一些实施方式中,参照图2,负极材料包括活性材料100;
活性材料100包括硅酸锂120、非水溶性硅酸盐140和硅氧材料160;
其中,非水溶性硅酸盐140包覆于硅酸锂120的表面;
所述硅酸锂120和/或所述非水溶性硅酸盐140中包含有所述硅氧材料160,
其中,所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
在一些实施方式中,由下述制备方法可知,预锂化的硅氧材料经表面刻蚀(材料主要包含硅酸锂120,通常内核包括硅酸锂120,表面形成氧化硅层),为非水溶性硅酸盐形成留出了孔隙,随后与含金属M和/或金属A的物质反应,获得非水溶性硅酸盐包覆硅酸锂120的结构;
同时预锂化的硅氧材料经后续高温处理后发生硅基歧化,形成了硅氧材料160分散或镶嵌于硅酸锂120和/或非水溶性硅酸盐140中的结构。
可选地,非水溶性硅酸盐140包括但不限于不溶于极性溶液(诸如水性溶液)的硅酸盐。
可选地,硅氧材料(或称为硅基活性材料)包括纳米硅、硅氧化物、硅碳化物、硅氮化物、硅硫化物或硅合金中的至少一种。
参照图3,可选地,负极材料还包括包覆层200,其包覆于活性材料100的表面。
在上述方案中,硅氧材料(或称为硅基活性材料,包括纳米硅、硅氧化物、硅碳化物、硅氮化物、硅硫化物或硅合金等)镶嵌在骨架(即硅酸盐的骨架)结构上,外层的非水溶性硅酸盐与内部的硅酸锂为同一硅氧骨架上生长形成的不同晶型的硅酸盐,两种不同材料的硅酸盐相连接,有利于活性材料的电化学性能的发挥,快速进行电子转移与脱嵌锂,有利于降低材料的内阻,提升锂离子转移能力。通过位于外层的非水溶性硅酸盐的骨架对硅氧材料的包裹,可以有效阻碍水与强碱性硅酸锂接触,抑制硅酸锂水解,从而有效改善材料产气,实现对材料的pH调控,提升加工性能。内层的硅酸锂与外层的非水溶性硅酸盐通过硅和硅氧材料紧密连接,两种硅酸盐材料的功函数差异导致两者在形成异质结界面后,可以在结界面提升电子转移效率,从而提升嵌锂深度,提升容量和循环性能。硅酸锂和非水溶性硅酸盐为同一硅氧骨架上生长形成的不同晶型的硅酸盐,能够形成紧密的异质结界面,不会形成真空断面,有利于异质结间材料电子转移,实现锂离子通过骨架结构及活性材料表面的硅氧材料进行有效传导,提升了材料的离子电导率,有利于材料的倍率性能的发挥。
以下作为本公开可选的技术方案,但不作为对本公开提供的技术方案的限制,通过以下可选的技术方案,可以更好的达到和实现本公开的技术目的和有益效果。
作为本公开可选的技术方案,其中,硅氧材料为SiO n,其中,0.5≤n≤1.5。可选地,硅氧材料可以是SiO n例如为SiO 0.5、SiO 0.8、SiO 0.9、SiO、SiO 1.1、SiO 1.2或SiO 1.5等。可选地,硅氧材料为SiO。可以理解地,SiO n的组成比较复杂,可以理解为由纳米硅均匀分散在SiO 2中形成,示例性地,硅氧材料可以包括硅单质、二氧化硅及氧化亚硅中的至少两种。
作为本公开可选的技术方案,硅酸锂包括Li 2SiO 3、Li 2Si 2O 5、Li 4SiO 4、Li 2Si 3O 7、Li 8SiO 6、Li 6Si 2O 7、Li 4Si 2O 7、Li 2Si 4O 7和LiSiO 3中的至少一种。需要说明的是,锂金属镶嵌于硅氧骨架中形成,表现为硅酸锂骨架结构。作为本公开可选的技术方案,硅酸锂包括Li 2O·mSiO 2,其中m满足0<m≤2,例如,m可以为0.1、0.3、0.5、0.7、0.9、1.0、1.2、1.4、1.5、1.6、1.8或2。
作为本公开可选的技术方案,非水溶性硅酸盐包括zA 2O·MO y·xSiO 2,其中,M包括Mg、Al、Ca、Ge、Cr、V、Ti、Sc、Co、Ni、Cu、Sr、Zn、Zr、Fe和Mn中的至少一种,A包括Li、Na、K中的至少一种,0.2≤x≤10.0,1.0≤y≤3.0,0≤z≤5.0。需要说明的是,金属A和/或金属M镶嵌于硅氧骨架中形成非水溶性硅酸盐的骨架结构。
在一些实施方式中,非水溶性硅酸盐还包括A 2O·nSiO 2,其中A包括Li、Na、K的至少一种,1≤n≤10。
作为本公开可选的技术方案,非水溶性硅酸盐可以包括但不限于Mg 2SiO 4、Al 2SiO 5、CaSiO 3、LiAlSiO 4、LiAlSiO、LiAlSi 2O 6、LiAlSi 3O 8、Li 2MgSiO 4,、MgSiO 3,或Li 2CaSiO 4
为了加速电子的传导,提高材料的粉末电导率,非水溶性硅酸盐的可选的功函数范围是2.5eV≤η≤7.0eV,可选地为4.50eV≤η≤6.5eV,可以在保证加工性能的基础上,有利于电子转移效率提升,极大的提升粉末电导率。可以理解地,合适的功函数范围能够使异质结间电子转移效率更高,非水溶性硅酸盐的骨架作为外层骨架,与导电碳层直接接触,其功函数需要高于碳层的功函数,且低于硅酸锂的功函数,则有更加有利于电子从外层向内部转移,提升导电率。
作为本公开可选的技术方案,非水溶性硅酸盐位于活性材料表面20nm~50nm的深度区域内,例如25nm~45nm、28nm~38nm或30nm~35nm,诸如20nm、24nm、26nm、28nm、30nm、34nm、36nm、38nm、40nm、44nm、46nm、48nm、50nm,或者上述任意两个端点值之间的区间值。即非水溶性硅酸盐位于自活性材料表面沿半径方向至例如20nm~50nm深度区域内,由于非水溶性硅酸盐位于活性材料的表层,由非水溶性硅酸盐的骨架及分布于非水溶性硅酸盐的骨架上的硅氧材料组成的表层结构,可以能够阻隔电解液进入活性材料内部,阻碍水与强碱硅酸锂接触,可以有效抑制硅酸锂水解。
作为本公开可选的技术方案,非水溶性硅酸盐的骨架与硅酸锂骨架连接形成异质结结构。可以理解地,硅氧材料镶嵌在骨架结构上,通过硅氧材料串联非水溶硅酸盐的骨架与硅酸锂骨架,进而使得两种骨架连接形成明显的异质结。这种异质结是由硅酸锂和非水溶性硅酸盐组成,两者都是通过共同的SiO 2骨架反应生长而成,由此界面间结合紧密连续,不会形成真空断面,有利于异质结间材料电子转移。这种异质结因为界面间功函数的差异以及适宜的界面间距离,可以促进电子在活性材料内部转移,提升导电性。通过异质结结构,能够有效的改善活性材料的导电性,提升材料的首效,同时抑制水解,控制pH。
作为本公开可选的技术方案,负极材料的XRD图谱中,硅酸锂的衍射特征峰的强度为I A,非水溶 性硅酸盐的衍射特征峰的强度为I B,且0.03≤I B/I A≤0.20。通过控制I B/I A的比值,可以使得电子凭借异质结传输能力达到最强,电子电导率可以达到15S/cm以上,有利于材料倍率性能的发挥。为了避免硅酸锂的流失,可选地,0.12≤I B/I A≤0.18,从而能够保证加工性能的条件下,确保该硅基材料的高电导率。
当非水溶性硅酸盐为非水溶性硅酸锂时,非水溶性硅酸盐的衍射特征峰的强度为I c,活性材料内部的硅酸锂的的衍射特征峰的强度为I,将非水溶性硅酸锂进行酸洗处理至不再发生反应后,处理后的非水溶性硅酸盐的衍射特征峰的强度为I D,且0.03≤(I C-I D)/2I≤0.2。其中,酸洗处理时为了去除表面非可溶性硅酸锂,留下SiO 2(硅氧骨架)沉积于表面,酸溶液为硫酸、盐酸、硝酸、王水等。在非水溶性硅酸盐为非水溶性硅酸锂的条件下,通过控制(I C-I D)/2I的比值,同样可以使得电子凭借异质结传输能力达到最强,进而有效发挥材料的倍率性能,确保硅基材料的高电导率。
作为本公开可选的技术方案,在活性材料表层的非水溶性硅酸盐中的Li元素的质量含量为W 1%,在活性材料内部的硅酸锂中的Li元素含量为W 2%,W 2>W 1≥0。即活性材料表面的Li元素浓度低于活性材料内部的Li元素的浓度。硅酸锂主要位于活性材料的内部,而非水溶性硅酸盐位于活性材料的外层,由非水溶性硅酸盐的骨架包覆的硅氧材料能够阻隔电解液进入活性材料内部,阻碍水与强碱硅酸锂接触,可以有效抑制硅酸锂水解,达到pH调控,抑制产气现象。
可选地,负极材料还包括形成于活性材料表面的碳层。可以理解地,位于活性材料表层的非水溶性硅酸盐的骨架及镶嵌于其中的硅氧材料可以直接与碳层接触,可以保障颗粒内部的导电通道和锂离子传输通道的稳定。
可选地,碳层的材质选自硬碳、软碳、碳纳米管、碳纳米纤维、石墨和石墨烯中的至少一种。
碳层的平均厚度为30nm~500nm,可选地,碳层的厚度可以是例如60nm~450nm、120nm~350nm或220nm~320nm,诸如30nm、50nm、100nm、150nm、200nm、250nm、300nm、350nm、400nm、450nm、500nm,或上述任意两个端点值之间的区间值,碳层的厚度但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。本公开的碳层厚度在上述范围内,有利于提高锂离子的传输效率,同时有利于材料大倍率充放电,有效保证负极材料的综合性能;同时保证负极材料的导电性且具备对材料的体积膨胀抑制性,保持负极材料的长循环性能。
可选地,活性材料的表面包覆有碳层时,负极材料中的碳的质量百分比含量为1.5wt%~10wt%,可选地,可以是例如2.0wt%~8.0wt%、4.0wt%~7.0wt%或5.0wt%~6.0wt%,诸如1.5wt%、4wt%、4.5wt%、5wt%、5.5wt%、6wt%、6.5wt%、7wt%、7.5wt%、8wt%、8.5wt%、9wt%或10wt%等,或上述任意两个端点值之间的区间值,但碳的质量百分比并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
负极材料中的锂的质量百分比含量为3wt%~15wt%,可选地,锂的质量百分比含量可以是例如4wt%~14wt%、6wt%~12wt%或8wt%~10wt%,诸如3wt%、3.5wt%、4.5wt%、5.5wt%、8wt%、9.5wt%、10.5wt%、12.1wt%、12.9wt%或15wt%等,或上述任意两个端点值之间的区间值,但锂的质量百分比并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。负极材料的锂含量在上述范围内,保证大部分锂源进入硅氧材料内部,形成硅酸锂骨架(即硅酸锂120),提升负极材料高首次库伦效率。另一方面,上述选取的硅酸锂能够控制表层锂量,减少表层处理后的损失锂损失,提升利用率,保证在活性材料表层的能在锂掺杂中形成硅酸盐的骨架(即非水溶性硅酸盐140),并具有非水溶性的特性,进而有效阻碍水与强碱硅酸锂(即硅酸锂120)接触,有效抑制硅酸锂水解,发挥pH调控,抑制产气的作用。负极材料的比表面积为1.0m 2/g~12.0m 2/g;可以是例如2.0m 2/g~10.0m 2/g、3.5m 2/g~6.0m 2/g或4.0m 2/g~5.5m 2/g,诸如1.0m 2/g、1.50m 2/g、2.00m 2/g、3.00m 2/g、4.00m 2/g、5.0m 2/g、7.0m 2/g、9.0m 2/g、10.0m 2/g或12.0m 2/g等等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。负极材料的比表面积在上述范围内,保证了材料的加工性能,有利于提高由该负极材料制成的锂电池的首次效率,有利于提高负极材料的循环性能。
作为本公开可选的技术方案,负极材料的平均粒径3.0μm~12.0μm,可以是例如4.0μm~11.0μm、5.0μm~10.0μm或6.0μm~8.0μm,诸如3.0μm、4.0μm、6.5μm、7.0μm、8.2μm、9.5μm、10.0μm或12.0μm等,或上述任意两个端点值之间的区间值。负极材料的平均粒径控制在上述范围内,有利于负极材料循环性能的提升。可选地,负极材料的平均粒径为4.5μm~9.0μm。
作为本公开可选的技术方案,负极材料的振实密度为0.6g/cm 3~1.2g/cm 3;可以是例如0.7g/cm 3~1.1g/cm 3、0.8g/cm 3~1.0g/cm 3或0.9g/cm 3~1.0g/cm 3,诸如0.6g/cm 3、0.7g/cm 3、0.75g/cm 3、0.8g/cm 3、0.85g/cm 3、0.9g/cm 3、0.95g/cm 3、1.0g/cm 3、1.1g/cm 3或1.2g/cm 3,等等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。负极材料的振实密度在上述范围内,有利于提高由该负极材料制成的锂电池的能量密度。
负极材料的pH值为8.5~12.0,可以是例如8.6~11.0、9.0~10.5或9.5~10.0,诸如8.5、8.8、8.9、 9.2、9.5、9.8、10.0、10.3、10.5、10.8、11.0、12.0等,或上述任意两个端点值之间的区间值。可以理解地,采用含锂化合物填充碳材料,可以有效降低材料的碱性,提高材料水系加工性能,提高负极材料的首效。
作为本公开可选的技术方案,负极材料的非水溶性硅酸盐中锂元素含量为pm,负极材料的总锂元素含量为p Li,其中满足0.01≤pm/p Li≤0.6。本公开发现,负极材料锂元素的含量分布在上述范围内,可以进一步保证活性材料表层生成稳定的非水溶性硅酸盐的骨架(即非水溶性硅酸盐140),进而有效阻止水与强碱硅酸锂(即硅酸锂120)接触,有效抑制硅酸锂水解,达到pH调控,抑制产气现象。
作为本公开可选的技术方案,负极材料为硅氧复合材料。
以下详细介绍本方案提供的制备方法:
本公开一实施方式提供一种负极材料的制备方法,包括以下步骤:
S10,将预锂化的硅氧材料进行表面刻蚀处理;
S20,将表面刻蚀处理后的硅氧材料与含金属M和/或金属A的物质(诸如金属单质M和/或金属单质A;含金属M和/或金属A的化合物)混合,在保护气氛下进行固相热反应,得到负极材料。
负极材料包括活性材料,活性材料包括贯穿活性材料的骨架结构及分布于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架及位于活性材料表面的非水溶性硅酸盐的骨架,非水溶性硅酸盐的骨架与硅酸锂骨架连接。
在上述方案中,通过将预锂化的硅氧材料进行表面刻蚀处理,将含金属M的物质与刻蚀后的硅氧材料固相热反应,使得刻蚀后的硅氧材料的表面形成非水溶性硅酸盐,能够有效隔绝硅酸锂等易溶强碱性物质溶于浆料,导致pH失控,抑制浆料产气,还可以预防活性硅氧材料和活性锂的损失,提升材料首效容量;硅酸锂和非水溶性硅酸盐为同一硅氧骨架上生长形成的不同晶型的硅酸盐,能够形成紧密的异质结界面,不会形成真空断面,有利于异质结间材料电子转移,提升了材料的离子电导率,有利于材料的倍率性能的发挥,并且整个制备过程简单,有利于大批量生产,降低成本。在步骤S10之前,制备方法还包括:
对硅氧材料进行碳包覆,得到碳包覆硅氧材料。
可以理解地,在硅氧材料上进行碳包覆,因为碳包覆层较为疏松,存在大量微孔道,而后续的锂源均可以通过碳包覆层的微孔道,渗透过碳包覆层而在硅氧材料表面进行反应,最后得到的负极材料中,碳包覆层依然是位于最外层。
作为本公开可选的技术方案,碳包覆包括气相包碳和/或固相包碳。
作为本公开可选的技术方案,采用气相包碳时,将硅氧材料在保护气氛下升温至600℃~1000℃,通入有机碳源气体,保温0.5h~10h后冷却。
在一些实施方式中,有机碳源气体包括烃类。在一些实施方式中,有机碳源包括烃类。在一些实施方式中,烃类包括烷烃、烯烃、炔烃、芳烃。在一些实施方式中,烃类为在600℃~1000℃下可气化的烃类。在一些实施方式中,烃类包括甲烷、乙烯、乙炔和苯中的至少一种。在一些实施方式中,烃类包括甲烷、乙烷、丙烷、乙烯、丙烯、乙炔、苯或甲苯等有机碳源中的至少一种。
作为本公开可选的技术方案,采用固相包碳时,将待包碳材料与碳源融合0.5h~2h后,将得到的碳混合物在600℃~1000℃下碳化2h~6h,冷却。
在一些实施方式中,碳源包括硬碳、软碳、碳纳米管、碳纳米纤维、石墨、石墨烯、沥青和有机-无机混合碳材料中的至少一种。
可选地,在步骤S10之前,制备方法还包括:
将硅氧材料与锂源反应得到的预锂化的硅氧材料;或
将碳包覆硅氧材料与锂源反应得到预锂化的碳包覆硅氧材料。
其中,硅氧材料为SiO n,其中,0.5≤n≤1.5,可以是SiO n例如为SiO 0.5、SiO 0.6、SiO 0.7、SiO 0.8、SiO 0.9、SiO、SiO 1.1、SiO 1.2或SiO 1.5等。可选地,硅氧材料为SiO。
在一些实施方式中,硅氧材料的平均粒径(D 50)为2.0μm-15.0μm;可以是例如3.0μm-13.0μm、6.0μm-11.0μm或7.0μm-10.0μm,诸如2.0μm、3.5μm、4.0μm、4.5μm、5.0μm、5.5μm、6.0μm、7.5μm、9.0μm、10.5μm、12μm或15.0μm等等,或上述任意两个端点值之间的区间值。本公开硅氧材料的平均粒径在上述范围内容,可以进一步保证负极材料的结构稳定性、热稳定性和长循环稳定性。
在一些实施方式中,碳包覆硅氧材料的平均粒径(D 50)为2.0μm-15.0μm;可以是例如3.0μm-13.0μm、6.0μm-11.0μm或7.0μm-10.0μm,诸如2.0μm、3.5μm、4.0μm、4.5μm、5.0μm、5.5μm、6.0μm、7.5μm、9.0μm、10.5μm、12μm或15.0μm等等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。可以理解地,碳包覆硅氧材料或硅氧材料 的粒径控制在上述范围内,能够避免锂化硅酸盐产物种类与分布不均而导致的循环稳定性的问题,有利于提高负极材料的结构稳定性、热稳定性和长循环稳定性。
可选地,碳包覆硅氧材料表面的碳层的厚度为30nm~500nm,可以是例如50nm~550nm、90nm~500nm、160nm~400nm或220nm~300nm,诸如30nm、50nm、60nm、70nm、80nm、90nm、100nm、150nm、200nm、300nm、400nm或500nm,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。可以理解地,包覆层过厚,锂离子传输效率降低,不利于材料大倍率充放电,降低负极材料的综合性能,包覆层过薄,不利于增加负极材料的导电性且对材料的体积膨胀抑制性能较弱,导致长循环性能差。
作为本公开可选的技术方案,锂源包括锂单质、含有锂的化合物或其混合物。作为本公开可选的技术方案,锂源包括氢化锂、烷基锂、金属锂、氢化铝锂、氨基锂和硼氢化锂中的至少一种。可选地,锂源还包括含有锂的氧化物、含有锂的氢化物等。
可选地,碳包覆硅氧材料或硅氧材料与锂源的反应温度为150℃~300℃,可以是例如180℃~280℃、200℃~260℃或210℃~240℃,诸如150℃、170℃、180℃、200℃、220℃、250℃、280℃或300℃等,或上述任意两个端点值之间的区间值。反应时间为2.0h~6.0h,可以是2.0h、2.5h、3.0h、3.5h、4.0h、4.5h、5.0h、5.5h或6.0h等,或上述任意两个端点值之间的区间值。通过控制反应温度和反应时间,使得至少部分锂源进入硅氧材料颗粒内部形成Li-SiO材料,大部分锂源沉积于硅氧材料的表层且与硅氧材料发生还原反应,生成氧化锂或氢氧化锂,这些氧化锂或氢氧化锂嵌设于硅氧材料表面的碳包覆层的孔隙内。
作为本公开可选的技术方案,碳包覆硅氧材料SiO n与锂源的质量比为1:(0.01~0.20),可选地,可以是例如1:(0.02~0.18)、1:(0.04~0.16)或1:(0.08~0.12),诸如1:0.01、1:0.03、1:0.05、1:0.1、1:0.15、1:0.2等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
作为本公开可选的技术方案,预锂化的碳包覆硅氧材料中的锂的质量百分比含量为3wt%~20wt%。本公开发现,本公开在预锂化的碳包覆硅氧材料中的锂含量在上述范围内,可以保证有效生成稳定性高的非水溶性硅酸盐,从而避免电解液进入活性材料内部,有效抑制产气现象。当预锂后的碳包覆硅氧材料中的锂含量过低或过高,都不利于二氧化硅骨架与含金属M的物质充分反应,生成性质稳定的非水溶性硅酸盐,以切断硅氧材料、硅酸锂与电解液的接触,抑制产气现象。
可选地,预锂化的碳包覆硅氧材料中的锂的质量百分比含量可以是例如4wt%~18wt%、6wt%~16wt%或9wt%~14wt%,诸如3wt%、5wt%、8wt%、10wt%、12wt%、15wt%、18wt%或20wt%等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
在一些实施方式中,可以采用酸洗处理对预锂化的硅氧材料或预锂化的碳包覆硅氧材料进行表面刻蚀处理。
作为本公开可选的技术方案,表面刻蚀处理采用的酸溶液具有的特性为:在将所述预锂化的硅氧材料进行表面刻蚀处理时,保持所述表面刻蚀的反应体系pH<7。作为本公开可选的技术方案,表面刻蚀处理采用的酸溶液包括但不限于盐酸、醋酸、硝酸、柠檬酸、草酸、硫酸、甲酸、苯酚、磷酸、磷酸氢化物、氢碘酸、氢溴酸、乙二胺四乙酸、羟基乙酸、葡萄糖酸、丁二酸中的至少一种。
作为本公开可选的技术方案,表面刻蚀处理的时间为0.5~10.0h。
表面刻蚀处理后,硅氧材料的表层不存在或微量存在硅酸锂,硅氧材料的表层主要为硅氧材料,且包含歧化后的二氧化硅。
可以理解地,表面刻蚀处理后的硅氧材料表面暴露的二氧化硅骨架与含金属M的物质反应,生成非水溶性硅酸盐。
S20,将表面刻蚀处理后的硅氧材料与含金属M和/或金属A的物质混合,在保护气氛下进行固相热反应,得到负极材料。
作为本公开可选的技术方案,含金属M的物质包括M金属单质和/或含金属M的化合物,含金属M的化合物包括金属M的碳酸盐、金属M的氧化物、金属M的氢氧化物、金属M的可溶性硅酸盐中的至少一种,其中,M选自Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种。示例性地,含金属M的物质可以是M的氧化物,例如氧化镁、氧化钙、氧化铝等;含金属M的物质可以是金属M的碳酸盐,例如碳酸镁、碳酸钙、碳酸铝。作为本公开可选的技术方案,含金属M的单质,其中,M选自Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种。
上述金属M和金属A分别选自电负性为1.0-1.9内的金属元素。
可选地,含金属M的物质为金属M氧化物。
作为本公开可选的技术方案,含金属A的物质包括:金属A单质、金属A的碳酸盐、金属A的氧化物、金属A氢氧化物中的至少一种,其中,A包括Li、Na、K中的至少一种。含金属A的单质中,金属A选自Li、Na、K中的至少一种。作为本公开可选的技术方案,含金属A的化合物包括金属A的碳酸盐、金属A的氧化物、金属A的氢氧化物、金属A的可溶性硅酸盐中的至少一种,其中,示例性地,含金属A的化合物可以是A的氧化物,例如氧化锂、氧化钾、氧化钠等;含金属A的化合物可以是金属A的碳酸盐,例如碳酸锂、碳酸钾、碳酸钠,其中碱性较强(诸如pH>10)的金属盐例如碳酸锂、碳酸钠、碳酸钾可以掺杂使用,不可单独使用。作为本公开可选的技术方案,表面刻蚀处理后的硅氧材料与含金属M的化合物(金属M单质或含M的化合物)的质量比为1:(0.01~0.1),可选地为1:(0.075~0.1)。本公开发现,当质量比过高,表面生成过量不溶性非活性MO·xSiO 2,0.2≤x≤10.0,会导致粉体可逆容量下降,导电性降低;当质量比过低,表示含金属M的物质含量过少,含金属M的物质不能充分与硅氧材料反应,不利于在硅氧材料的表层形成非水溶性硅酸盐的骨架,导致电解液容易穿过负极材料的表面与颗粒内部的硅酸锂反应,不利于抑制材料的碱性,使得负极材料在加工过程中产气严重,电池首效及循环稳定性下降。
作为本公开可选的技术方案,表面刻蚀处理后的硅氧材料与含金属A的单质或化合物的质量比为1:(0.01~0.1),同样本公开发现,不溶性非活性A 2O·nSiO 2,1≤n≤10,在本公开的上述比例范围中,可以在保证粉体的高逆容量,高导电性,使得金属A的化合物能充分与硅氧材料反应,有利于在硅氧材料的表层形成非水溶性硅酸盐的骨架,避免电解液与颗粒内部的硅酸锂反应,从而有效抑制材料的碱性,避免负极材料在加工过程中产气,从而进一步提高电池首效及循环稳定性。
可选地,表面刻蚀处理后的硅氧材料与含金属M的物质的质量比可以是例如1:(0.020~0.095)、1:(0.040~0.090)、1:(0.060~0.085)或1:(0.078~0.082),诸如1:0.1、1:0.2、1:0.3、1:0.4、1:0.5、1:0.6、1:0.7、1:0.075、1:0.081、1:0.083、1:0.085、1:0.087、1:0.091、1:0.093、1:0.095或1:0.1等等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
可选地,表面刻蚀处理后的硅氧材料与含金属A的单质或化合物的质量比可以是例如1:(0.020~0.095)、1:(0.040~0.090)、1:(0.060~0.085)或1:(0.078~0.082),诸如1:0.1、1:0.2、1:0.3、1:0.4、1:0.5、1:0.6、1:0.7、1:0.075、1:0.081、1:0.083、1:0.085、1:0.087、1:0.091、1:0.093、1:0.095或1:0.1等等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
作为本公开可选的技术方案,混合方式包括机械搅拌、超声分散、研磨分散中的至少一种。当然,可以理解的是,混合方式不限于采用上述方式,任何可以将预锂化的硅氧材料与含金属M的物质混合均匀的方式均可。
可选地,混合方式为球磨混合,球磨时间为3h~24h;可以是例如6h~21h、9h~17h或11h~15h,诸如3h、4h、5h、6h、8h、12h、16h、18h、20h或24h等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。可以理解地,充分球磨,可以使得含金属M的物质均匀附着在表面刻蚀处理后的硅氧材料表面或表面刻蚀处理后的碳包覆硅氧材料表面。
作为本公开可选的技术方案,保护气氛包括氮气、氦气、氖气、氩气、氪气和氙气中的至少一种。
在一些实施方式中,固相热反应为焙烧处理,焙烧可以在烧成炉中进行,使得焙烧充分进行。
可选地,固相热反应的温度为600℃~1200℃,可以是例如640℃~1160℃、720℃~920℃或780℃~820℃,诸如600℃、700℃、750℃、800℃、850℃、900℃、950℃、1000℃、1050℃、1100℃、1200℃等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用,可选750℃~1150℃。可以理解地,当反应温度过高,会导致反应剧烈,硅晶粒急剧长大,影响材料的循环性能;当反应温度过低,导致表面刻蚀处理后的硅氧材料表层的非水溶性硅酸盐的骨架无法生成。
可选地,固相热反应的时间为3h~12h,例如可以是5h~11h、6h~9h或7h~8h,诸如3h、4h、5h、6h、7h、8h、9h、10h、11h或12h等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。可以理解地,充分焙烧,可以在表面刻蚀处理后的硅氧材料表层生成非水溶性硅酸盐的骨架。
可选地,固相热反应的升温速率为1℃/min~5℃/min,例如可以是1℃/min、2℃/min、3℃/min、4℃/min或5℃/min等,或上述任意两个端点值之间的区间值,但并不仅限于所列举的数值,该数值范围内其他未列举的数值同样适用。
在上述固相热反应过程中,含金属M的物质与表面刻蚀处理后的硅氧材料表面歧化暴露的二氧化 硅骨架以及强碱性硅酸锂发生反应,生成非水溶性硅酸盐的骨架,抑制电解液容易穿过负极材料的表面与颗粒内部的硅酸锂反应,可以降低材料的pH值,进而影响整个负极浆料的PH值,改善预锂材料的加工稳定性问题,使得负极材料的首效得到提升。
可选地,在步骤S20之后,方法还包括:
对固相热反应得到的负极材料进行冷却及筛分使得负极材料的平均粒径为1μm~10μm,例如可以是例如2.5μm~9.5μm、3.5μm~7μm或4.5μm~6.5μm,诸如1μm、2μm、3μm、4μm、6μm、7μm、8μm、9μm或10μm等,或上述任意两个端点值之间的区间值。负极材料的平均粒径控制在上述范围内,有利于负极材料循环性能的提升。可选地,负极材料的平均粒径为4μm~7μm。
在一些实施方式中,筛分包括破碎、球磨、筛选或分级中的至少一种。
通过上述制备方法制得的负极材料,非水溶性硅酸盐的骨架与镶嵌在其上的硅氧材料组成的防水层,可以阻碍强碱性材料与溶剂反应,抑制产气,同时减少对于材料容量首效的影响,实现对该材料制成的负极浆料pH值的控制。其中,活性硅氧材料能够保持镶嵌于硅酸盐的骨架及硅酸锂骨架上,形成的骨架结构能够稳定起到膨胀缓冲作用,使得纳米硅晶粒镶嵌于整个颗粒体系中,使硅氧材料能够与导电碳层保持良好接触,实现导电性的提升,降低界面阻抗,可以保证颗粒内部的导电通道和锂离子传输通道稳定。
如图1所示,本公开一实施方式提供一种负极材料的制备方法,包括以下步骤:
S100,将预锂化的硅氧材料进行表面刻蚀处理;
S200,将表面刻蚀处理后的硅氧材料与含金属M的化合物混合,在保护气氛下进行固相热反应,得到负极材料。
在一些实施方式中,表面刻蚀处理后的硅氧材料还可以额外地与含金属A的物质混合,金属A包括碱金属元素,可选的,金属A包括Li、Na和K中的至少一种。
本公开提供一种锂离子电池,锂离子电池包含上述第一方面的负极材料或上述第二方面的制备方法制得的负极材料。
本公开提供的负极材料,硅氧材料镶嵌在骨架结构上,外层的非水溶性硅酸盐的骨架与内部的硅酸锂骨架连接,有利于活性材料的电化学性能的发挥,快速进行电子转移与脱嵌锂,有利于降低材料的内阻,提升锂离子转移能力。通过位于外层的非水溶性硅酸盐的骨架对硅氧材料的包裹,可以有效阻碍水与强碱性硅酸锂接触,抑制硅酸锂水解,从而有效改善材料产气,实现对材料的pH调控,提升加工性能。内层的硅酸锂与外层的非水溶性硅酸盐通过硅和硅氧材料紧密连接,两种硅酸盐材料的功函数差异导致两者在形成异质结界面后,可以在结界面提升电子转移效率,从而提升嵌锂深度,提升容量和循环性能。
另一方面,本公开提供的负极材料的制备方法,通过将预锂化的硅氧材料进行表面刻蚀处理,将含金属M的物质与刻蚀后的硅氧材料固相热反应,使得刻蚀后的硅氧材料的表面形成非水溶性硅酸盐,能够有效隔绝硅酸锂等易溶强碱性物质溶于浆料,导致pH失控,抑制浆料产气,还可以预防活性硅氧材料和活性锂的损失,提升材料首效容量;硅酸锂和非水溶性硅酸盐为同一硅氧骨架上生长形成的不同晶型的硅酸盐,能够形成紧密的异质结界面,不会形成真空断面,有利于异质结间材料电子转移,提升了材料的离子电导率,有利于材料的倍率性能的发挥,并且整个制备过程简单,有利于大批量生产,降低成本。
实施例
下面分多个实施例对本公开实施例进行进一步的说明。其中,本公开实施例不限定于以下的实施例。在保护范围内,可以适当的进行变更实施。
实施例1
(1)将碳包覆硅氧材料SiO/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO/C,其中,锂含量为10wt%;
(2)将预锂化材料放入10wt%柠檬酸溶液中浸泡1h,进行表面刻蚀,之后抽滤,并在80℃干燥环境下干燥24h;
(3)将氧化镁(5g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,球磨12h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于 活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5、Li 2SiO 3、Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为Mg 2SiO 4和Li 2MgSiO 4
负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.54m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为183nm。
实施例2
(1)将碳包覆硅氧材料SiO/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO/C,其中,锂含量为10wt%;
(2)将预锂化材料放入10wt%柠檬酸溶液中浸泡1h,进行表面刻蚀,之后抽滤,并在80℃干燥环境下干燥24h;
(3)将氧化镁(2.5g)、碳酸锂(4.6g)以及表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,球磨12h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5、Li 2SiO 3、Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为Li 2MgSiO 4
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.54m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为183nm。
实施例3
(1)将碳包覆硅氧材料SiO/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO/C,其中,锂含量为10wt%;
(2)将预锂化材料放入10wt%柠檬酸溶液中浸泡1h,进行表面刻蚀,之后抽滤,并在80℃干燥环境下干燥24h;
(3)将镁粉(3g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,在惰性气氛下球磨12h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5、Li 2SiO 3、Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为Mg 2SiO 4、MgSiO 3、Li 2MgSiO 4
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.54m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为183nm。本实施例制得的负极材料的XRD衍射图谱参见图6。
实施例4
步骤(1)与实施例1相近,不同之处在于锂含量为11wt%;
步骤(2)与实施例1相近,不同之处将预锂化材料放入12wt%的醋酸溶液中浸泡1.2h;
步骤(3)将Al 2O 3(7.5g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,球磨10h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5、Li 2SiO 3、Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为Al 2SiO 5、LiAlSiO 4、LiAlSi 2O 6和LiAlSi 3O 8
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.77m 2/g,负极材料中的锂的质量百分比含量为9.6wt%,碳层的厚度为177nm。
实施例5
步骤(1)与实施例1相近,不同之处在于锂含量为11wt%;
步骤(2)与实施例1相近,不同之处将预锂化材料放入1wt%的硝酸溶液中浸泡0.5h;
步骤(3)将Na 2CO 3(8g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,球磨10h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5、Li 2SiO 3和Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为LiNaSiO4。
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为1.00g/cm 3,比表面积为2.79m 2/g,负极材料中的锂的质量百分比含量为10.0wt%,碳层的厚度为193nm。
实施例6
步骤(1)与实施例1相近,不同之处,将碳包覆硅氧材料使用硅含量65%的硅氧材料SiO 0.75/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO 0.75//C,其中,锂含量为10wt%;
其他步骤与实施例1相同;
本实施例制备的负极材料的结构示意图参照图3,其包括活性材料100及形成于活性材料表面的碳层(即包覆层200),活性材料100包括骨架结构及镶嵌于骨架结构上的硅氧材料;骨架结构包括位于活性材料内部的硅酸锂骨架(即硅酸锂120)及位于活性材料表层的硅酸镁骨架(即非水溶性硅酸盐140),硅酸镁骨架(非水溶性硅酸盐140)与硅酸锂骨架连接。本实施例的硅酸锂骨架(即硅酸锂120)为Li 2Si 2O 5,Li 2SiO 3,Li 4SiO 4,活性材料表层(即非水溶性硅酸盐140)为Mg 2SiO 4,MgSiO 3,Li 2MgSiO 4
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为1.1g/cm 3,比表面积为2.47m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为187nm。
实施例7
(1)将碳包覆硅氧材料SiO/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO/C,其中,锂含量为10wt%;
(2)将预锂化材料放入10wt%柠檬酸溶液中浸泡1h,进行表面刻蚀,之后抽滤,并在80℃干燥环境下干燥24h;
(3)将氧化镁(5g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,球磨12h后,再转移至石墨坩埚中,在保护气氛下550℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料包括活性材料与氧化镁的混合物。
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.54m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为183nm。
实施例8
(1)将碳包覆硅氧材料SiO/C与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO/C,其中,锂含量为10wt%;
(2)将预锂化材料放入10wt%柠檬酸溶液中浸泡1h,进行表面刻蚀,之后抽滤,并在80℃干燥环境下干燥24h;
(3)将氧化镁(0.5g)与表面刻蚀后的预锂氧化亚硅(100g)一起加入球磨机中,在惰性气氛下球磨12h后,再转移至石墨坩埚中,在保护气氛下850℃处理10h后,破碎过筛分级得到负极材料。
本实施例制备的负极材料包括活性材料与氧化镁的混合物。
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.54m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为183nm。
实施例9
步骤(1)至(2)与实施例8相同;
步骤(3)与实施例8相近,不同之处在于,氧化镁的添加量为11g
本实施例制备的负极材料包括活性材料与氧化镁的混合物。
本实施例制备的负极材料的平均粒径(D 50)为5.0μm,振实密度为0.89g/cm 3,比表面积为3.2m 2/g,负极材料中的锂的质量百分比含量为9.2wt%,碳层的厚度为187nm。
实施例10
制备方法与实施例1相近,不同之处在于步骤(1),将硅氧材料SiO与金属锂反应,得到预锂化的碳包覆硅氧材料Li~SiO;
负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为3.01m 2/g,负极材料中的锂的质量百分比含量为10wt%,无碳层。
实施例11
制备方法与实施例1相近,不同之处在于步骤(2),柠檬酸溶液中浸泡时间为30min;
负极材料的平均粒径(D 50)为5.0μm,振实密度为0.98g/cm 3,比表面积为2.74m 2/g,负极材料中的锂的质量百分比含量为9.5wt%,碳层的厚度为189nm。
对比例1
采用预锂化的碳包覆硅氧材料SiO-Li/C作为负极材料,平均粒径(D 50)为5.14μm,振实密度为0.98g/cm 3,比表面积为3.24m 2/g,碳含量为5.0wt%。
对比例2
将11.9g MgCl 2(对应5g的MgO的摩尔量)溶液溶于500ml纯净水中,待完全溶解后,向溶液中加入100g SiO-Li/C(对比例1),充分搅拌10min;搅拌后,再进行抽滤,分离溶剂,然后将得到SiO-Li/Mg(OH) 2/C,放入箱式炉中,再Ar气体的保护下,800℃高温处理6h后,破碎分级得到负极材料。
需要说明的是,MgCl 2在碱性环境中能形成氢氧化镁胶体或沉淀,均匀包裹于碳包覆预锂材料SiO-Li/C粉体外围,在烧成过程中,MgO部分可能会与SiO 2以及其他硅酸骨架反应,生成含镁硅酸盐,其他的MgO会均匀分布包裹整个内核,形成一个MgO包覆层与最表面的碳包覆层,形成了一个多层包覆的核壳结构。
本对比例制备的负极材料的平均粒径(D 50)为5.17μm,振实密度为0.98g/cm 3,比表面积为3.40m 2/g,孔隙率为2.17wt%,碳含量为5.0wt%。
测试方法
1.电性能测试
将实施例1~3(S1~S6)及对比例1~4(R1~R5)所得的负极材料与人造石墨作为负极活性材料,按照SiO:石墨:CMC:SBR:SP:KS-6=9.2:82.8:2:2:2:2的质量比混合均匀后,涂覆在铜箔集流体上,经干燥获得负极极片备用。
首先对获得的极片进行扣式电池测试,电池组装在氩气手套箱中进行,以金属锂片为负极,电解液为1mol/LLiPF6+EC+EMC,隔膜为聚乙/丙烯复合微孔膜,电化学性能在电池测试仪器上进行,电池容量设置为标准的480mAh/g,充放电电压0.01~1.5V,充放电速率为0.1C,进行充放电测试,得到首次可逆容量、首圈充电容量和首圈放电容量。首次库伦效率=首圈放电容量/首圈充电容量。
重复循环50周,利用千分尺测量锂离子电池此时极片的厚度为H1,循环50圈后极片膨胀率=(H1-H0)/H0×100wt%。
重复50周循环,记录放电容量,作为锂离子电池的剩余容量;容量保持率=剩余容量/初始容量*100%。2.负极材料的平均粒径的测试方法:
2.粒径测试
采用马尔文Mastersizer 2000激光粒度测试仪对负极材料进行粒度测试,得到平均粒径。
3.负极材料的比表面积的测试方法:
采用麦克Tristar3020型比表面积与孔径分析仪对负极材料进行比表面积测试,称取一定质量粉末,在真空加热状态下进行完全脱气,去除表面吸附质后,使用氮气吸附法,通过吸附氮气量,计算出颗粒的比表面积。
4.负极材料的孔隙率测试:
采用气体置换法测试所述负极材料的孔隙率。计算方法:样品孔体积占总面积的百分比,P=(V 0-V)/V 0*100wt%,V 0:材料在自然状态下的体积,或称表观体积,单位:cm 3或m 3,V:材料的绝对密实体积,单位:cm 3或m 3
5.负极材料的振实密度测试:
采用国家标准GB/T 5162-2006《金属粉末振实密度的测定》。
6.负极材料碳含量测试:
负极材料样品在富氧条件下由高频炉高温加热燃烧,使碳氧化成二氧化碳,该气体经处理后 进入相应的吸收池,对相应的红外辐射进行吸收再由探测器转化成对应的信号。此信号由计算机采样,经线性校正后转换成与二氧化碳浓度成正比的数值,然后把整个分析过程的取值累加,分析结束后,此累加值在计算机中除以重量值,再乘以校正系数,扣除空白,即可获得样品中碳百分含量。利用高频红外碳硫分析仪(型号为上海徳凯HCS-140)进行样品测试。
7.负极材料水溶液中的锂含量测试:
负极材料样品在去离子水中浸泡(料水比例为50wt%),搅拌24小时后静置,待料液分层,取上清夜进行ICP测试,得到锂含量。
8.负极材料的XRD测试:
直接使用负极材料样品进行XRD测试。
9.负极材料的带隙测试:
直接使用负极材料样品进行紫外可见漫反射光谱测试得到光谱后,对光谱曲线积分得到极值波长后,通过公式Eg=1240/λ获得。
10.pH值测试
pH值为浆料pH值。
11.产气测试
产气是调浆完成后抽取4ml进入密封针筒(10ml量程小针筒),待8小时后观测针筒内体积浆料气体体积变化值。
12.锂元素的测试方法
(i)测定负极材料中非水溶性硅酸盐中的锂元素含量(以pm表示),测试方法为:
称取约0.5g左右的负极材料样品样品于铂金坩埚中,在750℃灼烧2h,直至碳元素灼烧完全,再加入4mL HNO 3,待酸与样品反应稳定后,将铂金坩埚置于350℃电热板上加热直至氢氟酸挥发不冒白烟,待坩埚冷却,再加入6mL的HCl,加热至残留物完全溶解,最后定容到100mL塑料容量瓶中,用ICP光谱仪测试,得到锂元素浓度。
(ii)测定负极材料中总锂含量(以p Li表示),测试方法为:方法与上述方法(i)相近,不同之处在于在添加HNO 3的同时还额外添加6mL HF,将4mL HNO 3和6mL HF尽心混合反应。
表1.测试结果统计表
Figure PCTCN2022140481-appb-000001
表2
Figure PCTCN2022140481-appb-000002
Figure PCTCN2022140481-appb-000003
结合表1与表2可知,并参阅图4及图5,实施例1~3提供的负极材料,硅氧材料镶嵌在骨架结构上,外层的非水溶性硅酸盐的骨架与内部的硅酸锂骨架连接,有利于活性材料的电化学性能的发挥,快速进行电子转移与脱嵌锂,有利于降低材料的内阻,提升锂离子转移能力。通过位于外层的非水溶性硅酸盐的骨架对硅氧材料的包裹,可以有效阻碍水与强碱性硅酸锂接触,抑制硅酸锂水解,从而有效改善材料产气,实现对材料的pH调控。锂离子能够通过骨架结构及活性材料表面的硅氧材料进行传导,提升了材料的离子电导率,有利于材料的倍率性能的发挥,部分实施例和对比例的性能数据对比请参照图4-6。
实施例1通过在SiO 2骨架上原位生长成非水溶性硅酸盐与硅酸锂形成稳定异质结界面,使得材料的导电性有一定的提升,达到了40.21S/cm。
实施例2中,通过氧化镁材料,球磨和固相反应,与外层的SiO 2骨架和强碱硅酸锂骨架反应,生成了不溶的硅酸镁盐(或者硅酸锂镁)等材料,硅酸镁锂的功函数与硅酸锂的功函数较接近,材料的粉末电导率相比于实施例1虽有一定下降,达到了20.97S/cm,但是在倍率上有更好的表现,在各个倍率下均相比于对比例1提升约1.5%~2.0%之间,表明异质结带来的导电性提升对于倍率提升有极大的促进作用。
实施例3中,使用镁粉,表面发生氧化还原反应生成MgO与SiO 2,进一步提升容量和首效,而MgO与SiO 2反应形成非水溶性硅酸盐(硅酸镁),可以隔绝浆料与强碱硅酸盐。但是因为Mg还原了SiO 2骨架,使通过硅酸锂延伸出的部分硅氧材料被破坏,材料颗粒的部分表面形成紧密的非水溶性硅酸盐界面,因此实施例3的粉末电导率降低相对于实施例1,略有降低。根据实施例3的XRD的数据(图6)可以发现,复合负极材料仅含有Si/硅酸锂/硅酸镁三种组分,而通过三种材料的组合,结合溶出液中锂含量的情况,可以发现微量硅酸镁集中在复合负极材料颗粒表面,新的硅酸盐界面形成异质结结构,因此其粉末电导率均远大于硅酸锂/硅和硅酸镁/硅样品(0.1-10S/cm),由此可以发现复合负极材料颗粒表面的异质结结构。
并且,根据实施例1至3的UV-vis表征测试结果可知,实施例1、2与3,其带隙分别为0.63eV、0.78eV、0.73eV,表明异质结作用通过改变能带并提升导电性,而异质结的形成有利于实现了材料电化学性能的提升。
同时,实施例4使用Al 2O 3,实施例5使用Na 2CO 3,分别在硅氧化物上原位生长成非水溶性硅酸盐与硅酸锂形成稳定异质结界面,同样使得材料的电化学性能有一定的提升。实施例6通过利用硅含量65%的硅氧材料以及氧化镁,同样可以在硅氧化物上原位生长成非水溶性硅酸盐与硅酸锂形成稳定异质结界面,并获得高电化学性能的负极材料。根据实施例1至9以及对比例1~2可知,通过XRD对比可溶性硅酸锂与非水溶性硅酸盐(例如硅酸镁)最强衍射峰强度,实施例1至9的I A/I B在本公开的范围内,均可以获得相较于对比例更高的电化学性能。
此外,当I A/I B≥0.10以上时,负极材料的溶解锂含量骤降,负极材料外层稳定的非水溶性硅酸盐已经形成,从而可以进一步有效抑制负极材料的产气。可选地,0.12≤I B/I A≤0.18。因为非水溶性硅酸盐(诸如硅酸镁)在表层堆积过后会削弱异质结界面效应作用,使电导率反而趋近非水溶性硅酸盐(诸如硅酸镁),降低粉末电导率,继而影响材料的电化学水平。
对比例1中常规预锂材料,材料粉末电导率较低,这是因为硅基材料以及硅酸锂本身为绝缘体或半导体,作为电芯材料其导电性较差,因此从粉末电导率表征可以发现,其粉末电导率为7.21S/cm,而常规石墨负极材料的粉末电导率为250S/cm以上,即便在表面进行导电碳包覆,其导电率也与石墨负极材料存在巨大差异。
对比例2通过沉积法在颗粒碳表面包覆一层氧化镁包覆层,氧化镁包覆层沉积于导电层外层,氧化镁包覆层遮盖了导电碳层,减少了导电碳层结构与导电剂的接触,因此,其粉末电导率有明显下降 (0.37S/cm)。并且该材料制得的电池在0.5C,1C,2C的倍率容量保持率分别相比于对比例1下降了超过3%以上。
本公开实施例1-6相比于实施例7,在处理温度保持在本公开的范围内,可以有效保证表面刻蚀处理后的硅氧材料与含有M或A的化合物的高效率反应,不仅实现对材料的pH调控,避免产气发生,同时有效提高了粉末导电率和倍率性能,说明形成了更加稳定的异质结结构。实施例7因为处理温度偏低,导致表面硅酸锂和SiO 2骨架和氧化镁发生反应缓慢,引起产气发生,但产气量显著低于对比例,同时粉末导电率相比于对比例有所提升,倍率性能低于实施例1,说明已形成异质结结构。
同时,电池的循环容量保持率也与负极材料中的异质结结构有一定联系,参照图4,其中,导电性良好的实施例1及2,50周容量保持率均在90%以上,而呈现出两级分化,没有异质结结构的对比例1,50周容量保持率低了接近10%,而对比例2中因为表面包覆氧化镁导致导电性下降,容量无法发挥,从而导致电化学性能下降。
根据实施例与对比例的材料溶液中Li的浓度数据可以发现,实施例1,实施例2,实施例3,三个样品,其溶液中均仅有低于20ppm的锂离子,属于误差范围,由此可以证明三个样品的表层中完全不含有可溶性硅酸锂,而对比例1作为标准预锂样品,其溶液中锂含量含有2000ppm以上,表明如果不做处理,可溶性硅酸锂会溶解于溶剂当中,部分硅酸因为水解从而导致pH上升。
同时本公开实施例1-6中,其pm/p Li的范围在本公开的范围内,可以进一步保证材料的高质荷传导能力,进一步有效抑制材料的碱性,避免负极材料在加工过程中产气,从而进一步提高电池首效及循环稳定性。
申请人声明,本说明书中描述的实施例旨在解释本公开,所提到的具体物质、配方比例以及反应条件只不过是本公开上述所提到的物质、配方比例以及反应条件的具体体现并非对本公开进一步限定,即不意味着本公开必须依赖上述详细方法才能实施。所属技术领域的技术人员应该明了,凡基于本公开上述内容所实现的技术均属于本公开的范围,对本公开的任何改进,对本公开产品各原料的等效替换及辅助成分的添加、具体方式的选择等,均落在本公开的保护范围和公开范围之内。
工业实用性
本公开提供的负极材料能够提升加工性能,具有优异的电化学循环及抑制膨胀性能,可延长锂离子电池的使用寿命,且其制备方法简单、成本低、易于实现工业化生产,故具有优异的工业实用性能。

Claims (13)

  1. 一种负极材料,其特征在于,所述负极材料包括活性材料,所述活性材料包括贯穿所述活性材料的骨架结构及镶嵌于所述骨架结构上的硅氧材料;所述骨架结构包括位于所述活性材料内部的硅酸锂的骨架及位于所述活性材料表层的非水溶性硅酸盐的骨架,所述非水溶性硅酸盐的骨架与所述硅酸锂的骨架连接;
    其中,所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
  2. 一种负极材料,其特征在于,所述负极材料包括活性材料;
    所述活性材料包括硅酸锂、非水溶性硅酸盐和硅氧材料;
    其中,所述非水溶性硅酸盐包覆于所述硅酸锂的表面;
    所述硅酸锂和/或所述非水溶性硅酸盐中含有所述硅氧材料,
    其中,所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.03≤I B/I A≤0.2。
  3. 根据权利要求1或2所述的负极材料,其特征在于,其满足以下条件a~g的至少一者:
    a.所述硅氧材料为SiO n,其中,0.5≤n≤1.5;
    b.所述硅酸锂包括Li 2SiO 3、Li 2Si 2O 5、Li 4SiO 4、Li 2Si 3O 7、Li 8SiO 6、Li 6Si 2O 7、Li 4Si 2O 7、Li 2Si 4O 7和LiSiO 3中的至少一种;
    c.所述非水溶性硅酸盐包括zA 2O·MO y·xSiO 2,其中,M包括Mg、Al、Ca、Ge、Cr、V、Ti、Sc、Co、Ni、Cu、Sr、Zn、Zr、Fe和Mn中的至少一种,A包括Li、Na、K中的至少一种,0.2≤x≤10.0,1.0≤y≤3.0,0≤z≤5.0;
    d.所述非水溶性硅酸盐还包括A 2O·nSiO 2,其中,其中A包括Li、Na、K中的至少一种,1≤n≤10;
    e.所述非水溶性硅酸盐的功函数范围为2.5eV≤η≤7.0eV;
    f.所述非水溶性硅酸盐位于所述活性材料表面20nm~50nm的深度区域内;
    g.所述非水溶性硅酸盐中的Li元素的质量含量为W 1%,所述硅酸锂中的Li元素含量为W 2%,W 2>W 1≥0。
  4. 根据权利要求1-3中任一项所述的负极材料,其特征在于,其满足以下条件a~j的至少一者:
    a.所述负极材料还包括存在于所述活性材料表面的碳层;
    b.所述碳层的平均厚度为30nm~500nm;
    c.所述负极材料的振实密度为0.6g/cm 3~1.20g/cm 3
    d.所述负极材料的比表面积为1.0m 2/g~12.0m 2/g;
    e.所述负极材料的平均粒径为3.0μm~12.0μm;
    f.所述负极材料中的碳的质量百分比含量为1.5wt%~10.0wt%;
    g.所述负极材料中的锂的质量百分比含量为3wt%~15wt%;
    h.所述负极材料的pH为8.5~12.0;
    i.所述负极材料的XRD图谱中,所述硅酸锂的最强衍射特征峰的强度为I A,所述非水溶性硅酸盐的最强衍射特征峰的强度为I B,且0.12≤I B/I A≤0.18;
    j.所述负极材料的非水溶性硅酸盐中锂元素含量为pm,所述负极材料的总锂元素含量为p Li,其中0.01≤pm/p Li≤0.6。
  5. 一种负极材料的制备方法,其特征在于,包括以下步骤:
    将预锂化的硅氧材料进行表面刻蚀处理;
    将表面刻蚀处理后的硅氧材料与含金属M和/或金属A的物质混合,在保护气氛下进行固相热反应,得到所述负极材料。
  6. 根据权利要求5所述的方法,其特征在于,其满足以下条件i~iv的至少一者:
    (i)所述含金属A的物质包括:金属A单质、金属A的碳酸盐、金属A的氧化物、金属A氢氧化物中的至少一种,其中,A包括Li、Na、K中的至少一种;
    (ii)所述含金属M的物质包括金属M单质、金属M的碳酸盐、金属M的氧化物、金属M的氢氧化物中的至少一种,其中,M包括Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种;
    (iii)所述表面刻蚀处理后的硅氧材料与所述含金属M和/或金属A的物质的质量比为1:(0.01~0.1);
    (iv)所述表面刻蚀处理后的硅氧材料与所述含金属M和/或金属A的物质的质量比为1:(0.075~0.1)。
  7. 一种负极材料的制备方法,其特征在于,包括以下步骤:
    将预锂化的硅氧材料进行表面刻蚀处理;
    将表面刻蚀处理后的硅氧材料与含金属M的化合物混合,在保护气氛下进行固相热反应,得到所述负极材料。
  8. 根据权利要求7所述的方法,其特征在于,其满足以下条件a~d的至少一者:
    a.所述含金属M的化合物包括金属M的碳酸盐、金属M的氧化物、金属M的氢氧化物中的至少一种,其中,M包括Mg、Al、Ca、Ge、Cr、Pb、Sr、Zn、Zr、Fe和Mn中的至少一种;
    b.所述表面刻蚀处理后的硅氧材料与所述含金属M的化合物的质量比为1:(0.01~0.1);
    c.所述表面刻蚀处理后的硅氧材料与所述含金属M的化合物的质量比为1:(0.075~0.1);
    d.所述含金属M的化合物为金属M的氧化物。
  9. 根据权利要求5-8中任一项所述的方法,其特征在于,其满足以下条件a~f的至少一者:
    a.所述混合方式包括机械搅拌、超声分散及研磨分散中的至少一种;
    b.所述混合方式为球磨混合,所述球磨时间为3h~24h;
    c.所述保护气氛的气体包括氮气、氦气、氖气、氩气、氪气和氙气中的至少一种;
    d.所述固相热反应的温度为600℃~1200℃;
    e.所述固相热反应的时间为3h~12h;
    f.所述固相热反应的升温速率为1℃/min~5℃/min。
  10. 根据权利要求5-9任一项所述的方法,其特征在于,其满足以下条件a~k的至少一者:
    a.所述预锂化的硅氧材料为预锂化的碳包覆硅氧材料;
    b.所述预锂化的碳包覆硅氧材料由碳包覆硅氧材料与锂源反应得到;
    c.所述硅氧材料为SiO n,其中,0.5≤n≤1.5;
    d.所述硅氧材料的平均粒径(D 50)为2.0μm~15.0μm;
    e.所述碳包覆硅氧材料表面的碳层的厚度为30nm~500nm;
    f.所述锂源包括锂单质或含有锂的化合物中的至少一种;
    g.所述锂源包括氢化锂、烷基锂、金属锂、氢化铝锂、氨基锂和硼氢化锂中的至少一种;
    h.所述碳包覆硅氧材料与所述锂源的反应温度为150℃~300℃;
    i.所述碳包覆硅氧材料与所述锂源的反应时间为2.0h~6.0h;
    j.所述碳包覆硅氧材料与所述锂源的质量比为1:(0.01~0.20);
    k.所述预锂化的碳包覆硅氧材料中的锂的质量百分比含量为3wt%~20wt%。
  11. 根据权利要求5-9任一项所述的方法,其特征在于,在将所述预锂化的硅氧材料进行表面刻蚀处理之前,所述方法还包括:
    将所述硅氧材料与锂源反应得到的预锂化的硅氧材料;或
    将碳包覆硅氧材料与锂源反应得到的预锂化的碳包覆硅氧材料。
  12. 根据权利要求5-9任一项所述的方法,其特征在于,其满足以下条件a~c的至少一者:
    a.所述表面刻蚀处理采用的酸溶液具有的特性为:在将所述预锂化的硅氧材料进行表面刻蚀处理时,保持所述表面刻蚀的反应体系pH<7;
    b.所述表面刻蚀处理采用的酸溶液包括盐酸、醋酸、硝酸、柠檬酸、草酸、硫酸、甲酸、苯酚、磷酸、磷酸氢化物、氢碘酸、氢溴酸、乙二胺四乙酸、羟基乙酸、葡萄糖酸、丁二酸中的至少一种;
    c.所述表面刻蚀处理的时间为0.5h~10.0h。
  13. 一种锂离子电池,其特征在于,所述锂离子电池包含权利要求1-4任一项所述的负极材料或根据权利要求5-12任一项所述的负极材料的制备方法制得的负极材料。
PCT/CN2022/140481 2021-12-29 2022-12-20 负极材料及其制备方法、锂离子电池 WO2023125171A1 (zh)

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