A battery negative electrode material and a preparation method thereof
By atomically dispersing germanium in a metal sulfide framework and reconstructing metal-sulfur bonds using the germanium "chemical scissors" effect, the volume expansion problem of germanium-based anode materials was solved, resulting in a sodium-ion battery anode material with high stability and high rate performance.
Patent Information
- Application Number
- CN202210377601.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-12
- Publication Date
- 2025-11-04
- Estimated Expiration
- 2042-04-12
AI Technical Summary
Germanium-based sodium-ion battery anode materials suffer from significant volume expansion and particle agglomeration during cycling, leading to rapid capacity decay. Existing nano-sizing and carbon coating processes are insufficient to effectively address these issues.
High-specific-capacity metallic germanium is atomically dispersed into a highly stable metal sulfide framework. The metal-sulfur bond is reconstructed through the germanium "chemical scissors" effect, forming an anode material that combines a highly stable Ti-S framework structure with a Ge-S weak bond structure, thereby suppressing germanium aggregation and volume expansion.
High cycle stability and high rate performance of sodium-ion batteries were achieved. The GeTiS3 material has a specific capacity of more than 670 mAh g-1 after 100 cycles at 0.3C and more than 200 mAh g-1 after 10,000 cycles at 32C.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery materials, specifically relating to an anode material with excellent cycle stability and high rate performance and its preparation method. Background Technology
[0002] In the context of current new energy development, sodium-ion batteries are considered a next-generation energy storage technology with enormous development potential due to their low resource dependence and low cost advantages. Germanium metal possesses excellent electronic conductivity (approximately 100 times higher than silicon) and an extremely high theoretical sodium storage capacity (Na3Ge: 1,108 mAh g). -1 NaGe: 369mAh g -1 Germanium, with its relatively fast sodium-ion transport rate and excellent mechanical strength, has attracted much attention in the research of sodium-ion battery anode materials. However, metallic germanium has poor rate performance and undergoes huge volume expansion during cycling, leading to particle agglomeration and electrode pulverization, resulting in rapid capacity decay. These problems limit its application in energy storage batteries.
[0003] To improve the capacity and cycle stability of sodium-ion battery anode materials, researchers have developed various strategies, such as confining germanium nanoparticles with polymers (J. Mater. Sci. 2014, 49, 2279-2285) and introducing carbon nanomaterials for coating (J. Power Sources 2018, 396, 124-133; Small 2020, 16, 1905-260). However, these traditional nano-sizing and carbon coating processes are insufficient to suppress the aggregation and volume expansion of germanium and silicon, and cannot effectively address the performance limitations of germanium-based and silicon-based anodes.
[0004] Germanium readily forms compounds with various metals and nonmetals, thus acting as an "atomic scissor" to uniformly disperse within metal compounds, severing existing chemical bonds and forming new germanium-containing bonds. Based on this principle, germanium-based anode materials can be designed and fabricated: by atomically dispersing metallic germanium within a rigid and highly conductive crystal framework, and rearranging the crystal structure through a chemical tailoring effect, both high stability and rapid sodium ion insertion / extraction in germanium-based anode materials can be simultaneously achieved.
[0005] Layered transition metal sulfides possess good electrical conductivity and a high theoretical sodium storage capacity; for example, TiS2 has a conductivity of 10⁴ S / m. -1 The theoretical capacity is as high as 239mAh g -1Ge can serve as an ideal material for dispersing metallic germanium. Therefore, we designed a method to disperse high-specific-capacity metallic germanium within a highly stable metal sulfide framework. Utilizing the "chemical scissors" effect of germanium, we reconstructed the metal-sulfur bonds, forming an anode material that combines a stable metal sulfide chain framework structure with a Ge-S weak bond structure. This effectively suppresses the aggregation and volume expansion effects of metallic germanium, achieving high cycle stability and ultra-high rate performance during sodium storage. Silicon and germanium belong to the same group of elements and have generally similar chemical reactivity; their performance can also be improved through material design using this mechanism. Summary of the Invention
[0006] The purpose of this invention is to provide a high-stability and high-rate bimetallic sulfur-based anode material for sodium-ion batteries and its preparation method. Taking GeTiS3 as an example, high-specific-capacity germanium metal is atomically dispersed into a highly stable metal sulfide TiS3 chain framework. The metal-sulfur bond is reconstructed using the germanium "chemical scissors" effect, forming an anode material that combines a highly stable TiS3 chain framework structure with a Ge-S weak bond structure. The atomically dispersed germanium is less prone to aggregation and volume expansion during charge and discharge, thus enabling highly reversible electrochemical reactions and high-rate characteristics. In summary, the bimetallic sulfur-based material design effectively solves the aggregation and volume expansion problems of germanium and silicon-based materials during cycling, thereby improving the capacity, rate performance, and cycle stability of sodium-ion batteries.
[0007] On one hand, this invention provides a bimetallic sulfur-based material for battery anodes and its preparation method. High-specific-capacity germanium or silicon is atomically dispersed within a highly stable metal-sulfur chain framework, exhibiting excellent cycle stability and high-rate characteristics. The bimetallic sulfur-based anode material is characterized by the chemical formula AMS3, where A includes one or more of germanium and silicon, and M includes one or more of Ti, Zr, V, and Nb. A chain-like open crystal structure is formed by a highly conductive and stable MS3 chain framework and weak AS bonds, facilitating rapid sodium ion insertion / extraction. A typical GeTiS3 structure is shown below. Figure 1 As shown, atomically dispersing metallic germanium or silicon into the rigid MS3 chain framework can effectively avoid silicon and germanium agglomeration and expansion effects during electrochemical processes, thereby improving the stability of the negative electrode.
[0008] Preferably, the bimetallic sulfur-based material has a size of 5 nanometers to 100 micrometers, more preferably 1 micrometer to 50 micrometers; and its shape can be granular, sheet-like, rod-like, linear, or three-dimensional porous, preferably linear.
[0009] On the other hand, the present invention provides a method for preparing a bimetallic sulfur-based material, comprising: mixing metal A, metal M and sulfur in a specific ratio using a corresponding mixing method, placing the mixture in an inert atmosphere or vacuum environment, and performing heat treatment.
[0010] Preferably, the molar ratio of the sum of metal A and metal M to sulfur is between 1:1 and 1:3, with a preferred ratio of 1:1.5.
[0011] Preferably, the mixing method includes grinding, ball milling, and rod milling, with grinding being the preferred method.
[0012] Preferably, the heat treatment temperature is 400–900°C, more preferably 600–800°C; and the heat treatment time is 0.5–24 h, more preferably 10–15 h.
[0013] Preferably, during the heat treatment process, the heating rate is 3 to 20 °C / min, and more preferably 5 to 10 °C / min.
[0014] Preferably, the inert atmosphere includes one of helium, argon, and nitrogen, or a mixture of the above gases, with nitrogen and argon being preferred.
[0015] Preferably, the pressure in the vacuum environment is 5 × 10⁻⁶. -5 Pa to 1 kPa, with 5 × 10 Pa being preferred. -5 Pa ~ 10 Pa.
[0016] On the other hand, the present invention provides a bimetallic sulfur-based anode material, comprising a conductive additive, a binder, and the bimetallic sulfur-based material. Preferably, the conductive additive comprises conductive carbon black, acetylene black, graphene, and carbon nanotube silicon, with acetylene black being the most preferred. Preferably, the binder comprises PVDF, sodium alginate, polyacrylic acid, and sodium carboxymethyl cellulose, with PVDF being the most preferred.
[0017] On another front, the present invention provides applications of bimetallic sulfur-based materials, including sodium-ion batteries, lithium-ion batteries, potassium-ion batteries, lithium-sulfur batteries, sodium-sulfur batteries, capacitors, and photoelectric conversion devices.
[0018] Therefore, this invention discloses a high-stability and high-rate battery anode material and its preparation method. Taking GeTiS3 as an example, high-specific-capacity germanium metal is atomically dispersed into a highly stable metal sulfide TiS2 framework. The metal-sulfur bond is reconstructed using the germanium "chemical scissors" effect, forming an anode material with both a highly stable Ti-S framework structure and a Ge-S weak bond structure. The atomically dispersed germanium is less prone to aggregation and volume expansion during charge and discharge, thus enabling highly reversible electrochemical reactions and high-rate characteristics. The bimetallic sulfur-based material design effectively solves the volume expansion problem of germanium and silicon-based materials during cycling, thereby improving the capacity, rate performance, and cycle stability of sodium-ion batteries. Tests show that this bimetallic sulfur-based material has superior capacity and cycle stability as a sodium-ion battery anode material; for example, GeTiS3 exhibits a capacity greater than 670 mAh g⁻¹ after 100 cycles at 0.3C. -1The specific capacity, at a 32C rate, still retains more than 200 mAh g after 10,000 cycles. -1 The specific capacity is high. Overall, this invention proposes a bimetallic sulfur-based material for sodium-ion battery anodes, characterized by high specific capacity and high cycle stability. Its manufacturing process is compatible with current conventional lithium-ion battery electrode material manufacturing processes, is simple and environmentally friendly, and suitable for large-scale production applications. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the GeTiS3 crystal structure of the present invention;
[0020] Figure 2 The cycling stability of GeTiS3 at 32C rate in Example 1 of this invention; Detailed Implementation
[0021] The present invention is further illustrated below through the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the invention. Unless otherwise specified, the reagents, materials, and instruments used in the following embodiments are all conventional reagents, materials, and instruments, and are all commercially available.
[0022] The preparation and properties of the bimetallic sulfur-based material of the present invention will be further illustrated below through specific embodiments. It should be understood that the specific parameters in the examples below are merely reasonable examples and are not intended to limit the specific values shown in the examples below.
[0023] Example 1
[0024] A vacuum solid-state synthesis method for GeTiS3 material. Germanium powder, titanium powder, and sulfur powder were added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a pre-vacuumed quartz tube. The temperature was increased to 650℃ at a heating rate of 5℃ / min and held for 12 hours. The sample was then cooled to room temperature and removed to obtain GeTiS3 material. After coin cell testing at 0.3C rate, it exhibited a capacitance greater than 670 mAh g⁻¹ after 100 cycles. -1 The specific capacity; after 10,000 cycles at 32C, it still has a capacity greater than 200 mAh g. -1 Specific capacity ( Figure 2 ).
[0025] Comparative Example 1
[0026] Germanium metal and acetylene black were fed in a 1:1 stoichiometric ratio and ball-milled at high energy to obtain a Ge-C composite material. After coin cell testing, its rate performance was significantly lower than that of GeTiS3, with a specific capacity of 300 mAh g at 0.3C. -1 At 32C rate, the specific capacity is 90mAh g. -1.
[0027] Example 2
[0028] An inert gas protected solid-state sintering method for GeTiS3 material. Germanium powder, titanium powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The mixture is heated to 650℃ at a heating rate of 5℃ / min and annealed for 10 hours. The sample is then cooled to room temperature and removed to obtain GeTiS3 material.
[0029] Example 3
[0030] An inert gas protected solid-state sintering method for GeNbS3 composite material. Metallic germanium powder, metallic Nb powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The mixture is heated to 750℃ at a heating rate of 5℃ / min and annealed for 10 hours. The sample is then cooled to room temperature and removed to obtain GeNbS3 material.
[0031] Example 4
[0032] A solid-state sintering method for SiTiS3 material under inert gas protection. Silicon powder, titanium powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The mixture is heated to 700℃ at a heating rate of 5℃ / min and annealed for 10 hours. The sample is then cooled to room temperature and removed to obtain SiTiS3 material.
[0033] Example 5
[0034] An inert gas protected solid-state sintering method for GeZrS3 material. Germanium powder, zirconium powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The mixture is heated to 660℃ at a heating rate of 5℃ / min and annealed for 10 hours. The sample is then cooled to room temperature and removed to obtain GeZrS3 material.
[0035] Example 6
[0036] A method for solid-state sintering of nano-GeTiS3 materials under inert gas protection. Germanium powder, titanium powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The mixture is heated to 650℃ at a heating rate of 5℃ / min and annealed for 10 hours. After cooling to room temperature, the sample is removed and ball-milled at high energy to obtain nano-GeTiS3 materials.
[0037] Example 7
[0038] A solid-state sintering method for SiVS3 material under inert gas protection. Metallic silicon powder, vanadium powder, and sulfur powder are added in a stoichiometric ratio of 1:1:3, ground and mixed evenly in an agate mortar, dried, and then placed in a tube furnace under nitrogen protection. The temperature is increased to 650℃ at a rate of 5℃ / min and annealed for 10 hours. The sample is then cooled to room temperature and removed to obtain SiVS3 material.
[0039] Example 8
[0040] A method for preparing GeTiS3 material electrode sheets. First, take 0.8g of GeTiS3 material prepared in Example 1, 0.1g of conductive acetylene black, and 0.1g of PVDF, dissolve them in N-methylpyrrolidone to prepare a slurry, stir evenly, and then coat it onto copper foil. Dry it in a vacuum oven at 80℃, and then use a die-cutting machine to cut it into electrode sheets with a diameter of 14 mm.
[0041] Example 9
[0042] A sodium-ion battery containing GeTiS3 material. The negative electrode is made of GeTiS3 material as described in Example 8, and the positive electrode is prepared by coating an aluminum foil with a slurry of carbon-coated Na3V2(PO4)3, acetylene black, and PVDF. The electrolyte is a 1M NaPF6 DME solution, and the separator is a glass fiber separator. Together, they constitute a sodium-ion battery containing GeTiS3 material.
Claims
1. A bimetallic sulfur-based material for battery anodes, comprising atomically dispersed high-specific-capacity germanium or silicon within a highly stable metal-sulfur chain framework, exhibiting excellent cycle stability and high-rate characteristics, characterized in that: (1) The chemical formula of the bimetallic sulfur-based material is AMS3, where A includes one or more of germanium and silicon, and M includes one or more of Ti, Zr, V, and Nb. The chain-like open crystal structure is formed by the highly conductive and stable MS3 chain backbone and AS weak bonds, which is conducive to the rapid insertion and extraction of sodium ions. (2) The atomic-level dispersion of metallic germanium or silicon into the rigid MS3 chain framework can effectively avoid silicon and germanium agglomeration and expansion effect in the electrochemical process, thereby improving the stability of the negative electrode.
2. The bimetallic sulfur-based material according to claim 1, characterized in that, Sizes range from 5 nanometers to 100 micrometers, and shapes include granules, flakes, rods, or three-dimensional porous forms.
3. A method for preparing a bimetallic sulfur-based material as described in claim 1, characterized in that, It includes the following two steps: (1) Synthesis of bimetallic sulfur-based material precursor: Metal A, metal M and sulfur in a specific ratio are mixed evenly by a corresponding mixing method and dried to obtain the precursor material; (2) Preparation of bimetallic sulfur-based materials: The precursor material obtained in (1) is placed in an inert atmosphere or vacuum environment and subjected to heat treatment to obtain bimetallic sulfur-based materials.
4. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, The molar ratio of the sum of metal A and metal M in step (1) to sulfur is between 1:1 and 1:
3.
5. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, The mixing method described in step (1) includes grinding, ball milling, and rod milling.
6. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, The heat treatment temperature in step (2) is 400-900℃ and the treatment time is 0.5-24h.
7. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, During the heating process of the heat treatment in step (2), the heating rate is 3 to 20 °C / min.
8. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, The inert atmosphere mentioned in step (2) includes one of helium, argon, and nitrogen, or a mixture of the above gases.
9. The method for preparing the bimetallic sulfur-based material as described in claim 3, characterized in that, The pressure in the vacuum environment described in step (2) is 5 × 10⁻⁶. -5 Pa ~ 1 kPa.
10. A bimetallic sulfur-based anode material, characterized in that, It includes conductive additives, binders, and the bimetallic sulfur-based material as described in claim 1 or 2, or the bimetallic sulfur-based material prepared by any one of the preparation methods described in claims 3-9.
11. The application of the bimetallic sulfur-based material according to claim 1 or 2, or the bimetallic sulfur-based material prepared by the preparation method according to any one of claims 3-9, or the bimetallic sulfur-based anode material according to claim 10, includes sodium-ion batteries, lithium-ion batteries, potassium-ion batteries, lithium-sulfur batteries, sodium-sulfur batteries, supercapacitors, or photoelectric conversion devices.