Lithium ion negative electrode material, preparation method thereof and lithium ion negative electrode slurry

Abstract

The invention relates to the field of lithium ion batteries, in particular to a lithium ion negative electrode material, a preparation method thereof and lithium ion negative electrode slurry. The structural formula is LixTiyLaNz, and x: y: z = (1-11): (1-6): (3-10); the negative electrode material LixTiyLaNz disclosed by the invention has mixed ion-electron conductivity, high ion conductivity and chemical stability, and can effectively inhibit the growth of lithium dendrites; rare earth ions La < 3 + > are doped, La < 3 + > has a large radius (1.16), Ti < 4 + > is replaced, lattice distortion is introduced, a lithium ion channel is expanded, a migration barrier is reduced, the working voltage is reduced, and the rate capacity is improved; negative ions N3 <-> are introduced to replace O2 <->, so that the electronegativity is reduced, the binding force of Li < + > is weakened, and the diffusion coefficient is increased; the working voltage is higher than the lithium deposition potential, and the lithium dendrite risk can be eliminated; the titanium-based composite material has the zero-strain characteristic of a titanium-based material and the high-conductivity advantage of nitride, is suitable for high-rate and low-temperature scenes, and even realizes negative electrode / solid-state interface dual functions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion batteries, and in particular to a lithium-ion anode material, its preparation method, and a lithium-ion anode slurry. Background Technology

[0002] Lithium-ion batteries, as the core of today's energy storage technology, play an irreplaceable role in electric vehicles, portable electronic devices, and renewable energy storage. However, the interlayer spacing (0.335 nm) of the negative electrode graphite limits the rapid insertion / extraction of lithium ions, resulting in a polarization voltage increase of over 50% during 10C charge / discharge; when charging below 0°C, the graphite overpotential exceeds 200 mV, and the proportion of metallic lithium deposition reaches 30%, forming dendrites that pierce the separator; low-temperature SEI film rupture-repair cycle increases the charge transfer impedance (Rct) by 5 times, and the coulombic efficiency drops below 80%. The "zero strain" characteristics and high lithium intercalation potential (Ti) of lithium titanate materials... 4+ / Ti 3+ Redox potential is 1.55V vs. Li + / Li, far from the lithium deposition potential, supports long cycle life and eliminates the risk of lithium dendrite formation. However, lithium titanate materials themselves have a low lithium-ion diffusion coefficient (10^-14 cm⁻¹). 2 The lithium titanate anode, operating at current densities on the order of * / s*, cannot rapidly complete the lithium-ion insertion / extraction reaction at high current densities. Secondly, while it avoids the low-temperature lithium plating problem of conventional graphite materials, it exhibits a significant capacity drop below 0°C, with its energy density often falling below 60% of its room-temperature value at -20°C. This is directly related to the contraction of lithium-ion diffusion channels in its spinel structure at low temperatures. Furthermore, its structural stability stems from strong Ti-O bonds and a rigid oxygen framework, but its low specific capacity (175 mAh / g) and high operating voltage (1.55 V) limit the overall cell energy density.

[0003] Therefore, there is an urgent need for a negative electrode material that can be used in high-rate and low-temperature environments. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a lithium-ion anode material, its preparation method, and a lithium-ion anode slurry.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of this invention is to provide a lithium-ion anode material with the structural formula Li x Ti y LaN z , where x:y:z = (1-11):(1-6):(3-10).

[0007] Preferably, x + 4y = 3 × (z - 1).

[0008] A second aspect of the present invention is to provide a method for preparing the above-mentioned lithium-ion anode material, comprising the steps of:

[0009] S1. Weigh out titanium source, lithium source and lanthanum source, mix them and add LiH and anhydrous ethanol solvent. After ball milling, Ti-La-N precursor composite phase is obtained.

[0010] S2. The Ti-La-N precursor composite phase is placed in a tube furnace and subjected to pre-sintering, sintering and cooling treatments. After grinding and sieving, the lithium-ion anode material is obtained.

[0011] Preferably, the titanium source includes: TiCl4, C 16 H 36 At least one of O4Ti and TiN.

[0012] Preferably, the lithium source includes at least one of Li3N and LiCl.

[0013] Preferably, the lanthanum source includes at least one of LaCl3, La(NH2)3, and LaN.

[0014] More preferably, at least one of the titanium source, the lithium source, or the lanthanum source contains nitrogen.

[0015] Preferably, the ball milling process includes: in an argon glove box, using ZrO2 grinding balls with a diameter of 5 mm, a ball-to-material ratio of 20:1, and continuously ball milling at 300-600 rpm for 8-16 hours.

[0016] Preferably, the pre-sintering treatment includes: sintering at a pressure of 0.2-1 MPa and a temperature increase of 5℃ / min to 300-500℃ under a nitrogen atmosphere for 4-9 hours.

[0017] The sintering process includes: heating to 600-700℃ at a heating rate of 5℃ / min, sintering at a constant temperature for 1-3 hours, and then heating to 800-900℃ at a heating rate of 5℃ / min, and sintering at a constant temperature for 6-10 hours.

[0018] A third aspect of the present invention is to provide a lithium-ion anode slurry, comprising, by weight, 85-98.5 parts of the above-mentioned lithium-ion anode material, 0.5-6 parts of conductive agent, 1-4 parts of binder, and 0-5 parts of additive.

[0019] Preferably, the conductive agent comprises at least one of graphite, acetylene black, carbon fiber, carbon nanotube, graphene, nano silver powder, and nano copper powder; the binder comprises at least one of carboxymethyl cellulose, polyvinyl alcohol, styrene-butadiene rubber, polyacrylic acid, polyacrylate, polyvinylidene fluoride, polyimide, polytetrafluoroethylene, and acrylonitrile multi-component copolymer aqueous dispersion; and the additive comprises at least one of oxalic acid, malonic acid, citric acid, and copper nitrate.

[0020] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0021] The negative electrode material of the present invention, Li x Ti y LaN z It possesses mixed ionic-electronic conductivity, and its high ionic conductivity and chemical stability can effectively suppress lithium dendrite growth; rare earth ion La 3+ Doping, La 3+ Large radius (1.16Å), replacing Ti 4+ Introducing lattice distortion expands lithium-ion channels, lowers migration barriers, reduces operating voltage, and increases rate capability; introducing N-ion anions... 3- , replacing O 2- Reduce electronegativity and weaken Li + It has a binding force that improves the diffusion coefficient; its operating voltage is higher than the lithium deposition potential, which can eliminate the risk of lithium dendrite formation; it combines the "zero strain" characteristics of titanium-based materials with the high conductivity of nitrides, making it suitable for high-rate and low-temperature applications, and even enabling dual functions of anode / solid-state interface. Attached Figure Description

[0022] Figure 1 This invention relates to a lithium-ion anode material, Li. x Ti y LaN z SEM images of different sintering times;

[0023] Figure 2 This invention relates to a lithium-ion anode material, Li. x Ti y LaN z Cyclic voltammetry curves for different sintering times. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0027] Example 1

[0028] This embodiment provides a method for preparing a lithium-ion anode material, the steps of which include:

[0029] S1. Weigh 5.7261g of TiCl4, 0.3483g of Li3N, and 1.8698g of La(NH2)3. After mixing, add 0.0794g of LiH and an appropriate amount of anhydrous acetonitrile solvent. In an argon glove box, use ZrO2 grinding balls (5mm in diameter) at a ball-to-material ratio of 20:1 and a rotation speed of 300-600 rpm for 12 hours to obtain the Ti-La-N precursor composite phase.

[0030] S2. The Ti-La-N precursor composite phase is placed in a tube furnace, and high-purity N2 is introduced at a pressure range of 0.2-1 MPa. The temperature is increased to 450°C at 5°C / min for pre-sintering and held at a constant temperature for 6 hours. The temperature is then increased to 650°C at 5°C / min for 1 hour, and then increased to 850°C at 5°C / min for 6 hours. After natural cooling to 60°C, the material is removed, ground, and sieved to obtain the lithium-ion anode material Li3Ti3LaN6.

[0031] Example 2

[0032] This embodiment provides another method for preparing lithium-ion anode materials, the steps of which include:

[0033] S1. Weigh 5.7261g of TiCl4, 0.3483g of Li3N, and 1.8698g of La(NH2)3. After mixing, add 0.0794g of LiH and an appropriate amount of anhydrous acetonitrile solvent. In an argon glove box, use ZrO2 grinding balls (5mm in diameter) at a ball-to-material ratio of 20:1 and a rotation speed of 300-600 rpm for 12 hours to obtain the Ti-La-N precursor composite phase.

[0034] S2. The Ti-La-N precursor composite phase is placed in a tube furnace, and high-purity N2 is introduced at a pressure range of 0.2-1 MPa. The temperature is increased to 450°C at 5°C / min for pre-sintering and held at this temperature for 6 hours. The temperature is then increased to 650°C at 5°C / min for 2 hours, followed by sintering at 850°C at 5°C / min for 8 hours. After natural cooling to 60°C, the material is removed, ground, and sieved to obtain the lithium-ion anode material.

[0035] Example 3

[0036] This embodiment provides another method for preparing lithium-ion anode materials, the steps of which include:

[0037] S1. Weigh 5.7261g of TiCl4, 0.3483g of Li3N, and 1.8698g of La(NH2)3. After mixing, add 0.0794g of LiH and an appropriate amount of anhydrous acetonitrile solvent. In an argon glove box, use ZrO2 grinding balls (5mm in diameter) at a ball-to-material ratio of 20:1 and a rotation speed of 300-600 rpm for 12 hours to obtain the Ti-La-N precursor composite phase.

[0038] S2. The Ti-La-N precursor composite phase is placed in a tube furnace, and high-purity N2 is introduced at a pressure range of 0.2-1 MPa. The temperature is increased to 450°C at 5°C / min for pre-sintering and held at this temperature for 6 hours. The temperature is then increased to 650°C at 5°C / min for 3 hours, and then increased to 850°C at 5°C / min for 10 hours. After natural cooling to 60°C, the material is removed, ground, and sieved to obtain the lithium-ion anode material.

[0039] Detection Examples

[0040] SEM images of Li3Ti3LaN6 material are shown below. Figure 1 As shown, the material has a granular structure with particle sizes of 1-3 μm and is distributed in an aggregated state.

[0041] Figure 2 The cyclic voltammetry curves for Li3Ti3LaN6 material are shown at 1.05V (vs. Li / Li). + The redox reaction occurs near the lithium titanate, which has a redox potential of 1.55V (vs Li / Li⁺), resulting in a lower operating voltage. At the same time, it is higher than the lithium deposition potential (typically 0.1V-0.3V), providing capacity without the risk of lithium dendrite formation. The redox peaks are symmetrical and close, and the material has a small volume change, exhibiting the "zero strain" characteristic of titanium-based materials.

[0042] In summary, the negative electrode material Li of this invention... x Ti y LaN z Medium rare earth ion La 3+ Doping leads to lattice distortion, expands lithium-ion channels, lowers the migration barrier, and reduces the redox peak, while simultaneously maintaining a higher peak than the lithium deposition potential, compared to lithium titanate (Li4Ti5O). 12 The LTO (Lithium Oxide-Total Hydrocarbon) operating voltage window is expanded, which can improve battery capacity and effectively suppress lithium dendrite growth. The redox peaks are symmetrical and close, combining the "zero strain" characteristics of titanium-based materials (volume change <1%) with the high conductivity of nitrides, making it suitable for high-rate and low-temperature applications, and even enabling dual functions of anode / solid-state interface.

[0043] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A lithium ion anode material, characterized in that, Li x Ti y LaN z , Wherein, x: y: z = (1-11): (1-6): (3-10).

2. The lithium-ion anode material of claim 1, wherein, x+4y=3×(z-1).

3. A method of producing the lithium ion anode material of any one of claims 1-2, characterized by the steps of Comprise: S1, take titanium source, lithium source, lanthanum source, after mixing, add LiH and anhydrous ethanol solvent, ball milling treatment, prepare Ti-La-N precursor composite phase; S2, the Ti-La-N precursor composite phase is placed in a tube furnace, pre-sintering treatment, sintering treatment and cooling treatment, grinding and sieving, the lithium ion negative electrode material is obtained.

4. The production method according to claim 3, characterized by, The titanium source includes at least one of TiCl4, C 16 H 36 O4Ti, TiN.

5. The preparation method according to claim 3, characterized in that, The lithium source comprises at least one of Li3N and LiCl.

6. The preparation method according to claim 3, characterized in that, The lanthanum source comprises at least one of LaCl3, La(NH2)3 and LaN.

7. The preparation method according to claim 3, characterized in that, The ball milling treatment comprises: in an argon glove box, using ZrO2 grinding ball with a diameter of 5mm, ball-to-material ratio of 20:1, ball milling at 300-600rpm for 8-16h.

8. The preparation method according to claim 3, characterized in that, The pre-sintering treatment comprises: under nitrogen atmosphere, with a pressure of 0.2-1MPa, heating to 300-500℃ at a rate of 5℃ / min, and sintering for 4-9h at constant temperature; The sintering treatment comprises: heating to 600-700℃ at a rate of 5℃ / min, sintering for 1-3h at constant temperature, and then heating to 800-900℃ at a rate of 5℃ / min, sintering for 6-10h at constant temperature.

9. A lithium-ion anode slurry, characterized by, The components comprise, by weight fraction: 85-98.5 parts of the lithium ion negative electrode material according to any one of claims 1-2, 0.5-6 parts of conductive agent, 1-4 parts of binder, and 0-5 parts of additive.

10. The lithium-ion anode slurry of claim 9, wherein, The conductive agent comprises at least one of graphite, acetylene black, carbon fiber, carbon nanotube, graphene, nano silver powder and nano copper powder; the binder comprises at least one of carboxymethyl cellulose, polyvinyl alcohol, butadiene rubber, polyacrylic acid, polyacrylate, polyvinylidene fluoride, polyimide, polytetrafluoroethylene and acrylonitrile multi-copolymer aqueous dispersion; and the additive comprises at least one of oxalic acid, malonic acid, citric acid and copper nitrate.

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