Electron-lithium ion mixed conductor material and preparation method thereof

Abstract

The invention relates to the technical field of conductor materials, in particular to an electron-lithium ion mixed conductor material and a preparation method thereof. According to the technical scheme, the sulfide solid electrolyte comprises a sulfide solid electrolyte core; the surface of the inner core is coated with the LiMS coating layer, M is at least one of V, Cr, Fe, Ni and Nb, the sulfide solid electrolyte is Li < 6-X > PS5-XCl < 1 + X >, x is greater than or equal to 0 and less than or equal to 0.6, and the thickness of the LiMS < 2 > coating layer is nanoscale. A novel electron-lithium ion mixed conductor material is successfully developed through an optimally designed in-situ reaction and preparation process, and the material can provide efficient ion and electron transmission paths in a positive electrode at the same time, significantly reduce interface impedance, improve the utilization rate of active substances, and improve the performance of a lithium ion battery. Therefore, the discharge capacity and the electrochemical performance of the all-solid-state battery are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of conductor materials technology, and in particular to an electron-lithium ion hybrid conductor material and its preparation method. Background Technology

[0002] All-solid-state lithium-ion batteries are considered an ideal choice for next-generation energy storage devices due to their advantages such as high energy density, high safety, and long cycle life. Among various solid electrolytes, sulfide solid electrolytes (such as Li6PS5Cl, Li...) are... 10 GeP2S 12 (etc.) due to its extremely high ionic conductivity (up to 10 at room temperature) -2 Its properties (on the order of S / cm) and good mechanical formability have made it a research hotspot.

[0003] However, in all-solid-state batteries using sulfide electrolytes, the cathode is typically a mechanical mixture of three phases: the active material (such as ternary NCM), the ion conductor (sulfide electrolyte), and the electronic conductor (such as conductive carbon black). This structure has an inherent flaw: the sulfide electrolyte (such as Li6PS5C) only provides ion conduction channels but lacks electronic conduction capabilities; while the electronic conductor (such as carbon black), while providing electronic channels, often hinders lithium-ion transport and may undergo adverse interfacial reactions with the sulfide electrolyte. This isolated and separately distributed "mixed but not fused" state of the ion-conducting and electronic-conducting phases makes it difficult to form a continuous, efficient, and matched synergistic conductive network within the cathode. The consequence is a mismatch and disconnect between the ion transport paths and the electron transport paths, resulting in a large amount of active material that cannot be effectively utilized, high interfacial transport resistance, and severely limiting the capacity utilization, rate performance, and cycle stability of the all-solid-state battery cathode.

[0004] To improve charge transport within the positive electrode, existing technologies typically employ methods such as increasing the amount of conductive agent or optimizing the electrode structure. However, these methods often have limited effectiveness and may sacrifice the battery's energy density. Therefore, this application proposes an electron-lithium ion hybrid conductor material and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to address the problem in the prior art where increasing the amount of conductive agent or optimizing the electrode structure usually sacrifices the energy density of the battery, and to propose an electron-lithium ion hybrid conductor material and its preparation method.

[0006] In a first aspect, the present invention provides an electronic-lithium ion hybrid conductor material, comprising:

[0007] Sulfide solid electrolyte core;

[0008] The LiMS2 coating layer covering the surface of the core, wherein M is at least one of V, Cr, Fe, Ni, and Nb;

[0009] The LiMS2 coating layer is formed through an in-situ reaction, giving the material both electronic conductivity and lithium-ion conductivity.

[0010] Optionally, the sulfide solid electrolyte is Li 6-X PS 5-X Cl 1+X , where 0 ≤ x ≤ 0.6.

[0011] Optionally, the thickness of the LiMS2 coating layer is at the nanometer level.

[0012] In a second aspect, the present invention provides a method for preparing an electron-lithium ion hybrid conductor material as described in the first aspect, comprising the following steps:

[0013] S1, Metal halide MX n Ball milling is performed, wherein M is at least one of V, Cr, Fe, Ni, and Nb, and X is at least one of F, Cl, Br, and I, and 2 ≤ n ≤ 4;

[0014] S2. The metal halide obtained in step S1 is mixed with the sulfide solid electrolyte by ball milling at a molar ratio of 1:100 to 1:10.

[0015] S3. Anneal the mixture obtained in step S2 under an inert atmosphere;

[0016] S4. The annealed product is ball-milled to obtain the electron-lithium ion hybrid conductor material.

[0017] Optionally, the ball milling process in step S1 is performed at a rotation speed of 500-600 rpm for 20-30 h.

[0018] Optionally, the ball milling process in step S2 is performed at a rotation speed of 200-300 rpm for 5-10 hours.

[0019] Optionally, the annealing treatment in step S3 is performed at a temperature of 400~500 ℃ for 2~5 h, and the inert atmosphere is argon.

[0020] Optionally, the ball milling in step S4 is performed at a speed of 100-200 rpm for 1-2 hours.

[0021] Optionally, the molar ratio of the metal halide to the sulfide solid electrolyte in step S2 is 1:50 to 1:20.

[0022] Optionally, the metal halide is at least one of VCl3, NbCl5, FeCl3, NiCl2, and CrCl3.

[0023] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0024] By constructing a LiMS2 nanocoating layer in situ on the surface of a sulfide electrolyte, a single ionic conductor is transformed into a bifunctional conductive unit, and a highly efficient and synergistic ion / electron transport network is established simultaneously, fundamentally solving the problem of two types of conduction obstacles in traditional cathodes.

[0025] The use of this material significantly improves the discharge specific capacity of the positive electrode in all-solid-state batteries, effectively enhancing the utilization rate of active materials and rate performance.

[0026] The nanoscale coating provides electron channels without affecting ion transport; its layered structure maintains ion conductivity and works synergistically with the electrolyte core.

[0027] This invention has successfully developed a novel electron-lithium ion hybrid conductor material through optimized in-situ reaction and preparation processes. This material can simultaneously provide efficient ion and electron transport paths within the positive electrode, significantly reduce interfacial impedance, and improve the utilization rate of active materials, thereby greatly enhancing the discharge capacity and electrochemical performance of all-solid-state batteries. Attached Figure Description

[0028] Figure 1 Comparison of XRD patterns of Embodiment 1 and Comparative Example 1 of the present invention;

[0029] Figure 2 This is an ionic conductivity diagram of Example 1 of the present invention;

[0030] Figure 3 This is an electronic conductivity diagram of Embodiment 1 of the present invention;

[0031] Figure 4 This is the ionic conductivity diagram of Example 6 of the present invention;

[0032] Figure 5 This is an electronic conductivity diagram of Embodiment 6 of the present invention. Detailed Implementation

[0033] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0034] Example 1

[0035] A method for preparing an electron-ion hybrid conductor composite material includes the following steps:

[0036] (1) Place 0.01 mol of VCl3 in a ball mill jar and ball mill at 500 rpm for 25 h to complete the pre-ball milling. Mix 0.0007 mol of pre-ball milled VCl3 with 0.01 mol of Li6PS5Cl and ball mill at 300 rpm for 8 h to obtain the mixture.

[0037] (2) The mixture was placed in a tube furnace and heated to 450°C at a heating rate of 5°C / min under an argon atmosphere. The mixture was kept at this temperature for 3 hours and then cooled to room temperature with the furnace. The mixture was then ball-milled again at a ball milling speed of 100 rpm for 1 hour to obtain an electron-ion composite material with Li6PS5Cl surface coated with intercalated lithium sulfide LiNbS2. Figure 1 By comparing the XRD patterns of the composite material and the original Li6PS5Cl (Comparative Example 1), it can be seen that the phase of the composite material is mainly Li6PS5Cl, with the presence of LiVS2 phase.

[0038] (3) The ionic conductivity and electronic conductivity of the composite material were measured, and the results are as follows: Figure 2 and Figure 3 As shown, its ionic conductivity is 2.93 mS / cm, and its electronic conductivity is 5.21 × 10⁻⁶ mS / cm. -3 The ionic conductivity (mS / cm) is very close to that of the original Li6PS5Cl in Comparative Example 1, while the electronic conductivity is increased by 4270 times, indicating that the composite material has excellent ionic and electronic conductivity.

[0039] Example 2:

[0040] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that "mixing 0.0007 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl" in Example 1 is replaced with "mixing 0.0001 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl".

[0041] Example 3:

[0042] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that "mixing 0.0007 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl" in Example 1 is replaced with "mixing 0.0003 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl".

[0043] Example 4:

[0044] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that "mixing 0.0007 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl" in Example 1 is replaced with "mixing 0.0005 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl".

[0045] Example 5:

[0046] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that "mixing 0.0007 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl" in Example 1 is replaced with "mixing 0.001 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl".

[0047] Example 6:

[0048] A method for preparing an electron-ion hybrid conductor composite material includes the following steps:

[0049] (1) Place 0.01 mol of NbCl5 in a ball mill jar and ball mill at 500 rpm for 25 h to complete the pre-ball milling. Mix 0.0007 mol of pre-ball milled NbCl5 with 0.01 mol of Li6PS5Cl and ball mill at 300 rpm for 8 h to obtain the mixture.

[0050] (2) The mixture was placed in a tube furnace and heated to 450°C at a heating rate of 5°C / min under an argon atmosphere. The mixture was kept at this temperature for 3 hours and then cooled to room temperature with the furnace. The mixture was then ball-milled again at a ball milling speed of 100 rpm for 1 hour to obtain an electron-ion composite material with Li6PS5Cl surface coated with intercalated lithium sulfide LiNbS2.

[0051] (3) The ionic conductivity and electronic conductivity of the composite material were measured, and the results are as follows: Figure 4 and Figure 5 As shown, its ionic conductivity is 2.92 mS / cm, and its electronic conductivity is 9.26 × 10⁻⁶ mS / cm. -3 mS / cm.

[0052] Example 7:

[0053] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that "mixing 0.0007 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl" in Example 6 is replaced with "mixing 0.0001 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl".

[0054] Example 8:

[0055] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that "mixing 0.0007 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl" in Example 6 is replaced with "mixing 0.0003 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl".

[0056] Example 9:

[0057] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that "mixing 0.0007 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl" in Example 6 is replaced with "mixing 0.0005 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl".

[0058] Example 10:

[0059] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that "mixing 0.0007 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl" in Example 6 is replaced with "mixing 0.001 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl".

[0060] Example 11:

[0061] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that “VCl3” in Example 1 is replaced with “VS2” in an equimolar ratio.

[0062] Example 12:

[0063] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that “NbCl5” in Example 1 is replaced with “NbS2” in an equimolar ratio.

[0064] Comparative Example 1:

[0065] This comparative example is the original Li6PS5Cl without any treatment.

[0066] Comparative Example 2:

[0067] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 1 only in that "mixing 0.0007 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl" in Example 1 is replaced with "mixing 0.0015 mol of pre-ball-milled NbCl5 with 0.01 mol of Li6PS5Cl".

[0068] Comparative Example 3:

[0069] A method for preparing an electron-ion hybrid conductor composite material, which differs from Example 6 only in that "mixing 0.0007 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl" in Example 6 is replaced with "mixing 0.0015 mol of pre-ball-milled VCl3 with 0.01 mol of Li6PS5Cl".

[0070] The ionic conductivity, electronic conductivity, and first-cycle discharge capacity of Examples 1-12 and Comparative Examples 1-3 are shown in the table below.

[0071] sample Ionic conductivity (mS / cm) Electron conductivity (mS / cm) Discharge specific capacity in the first week (mAh / g) Example 2 3.03 <![CDATA[7.00*10 -6 ]]> 171.9 Example 3 2.99 <![CDATA[9.8*10 -5 ]]> 175.4 Example 4 2.95 <![CDATA[3.5*10 -4 ]]> 181.0 Example 1 2.93 <![CDATA[5.21*10 -3 ]]> 182.6 Example 5 2.88 <![CDATA[7.1*10 -3 ]]> 184.3 Example 7 3.01 <![CDATA[1.12*10 -5 ]]> 172.4 Example 8 2.98 <![CDATA[3.36*10 -5 ]]> 176.6 Example 9 2.96 <![CDATA[5.75*10 -4 ]]> 182.3 Example 6 2.92 <![CDATA[9.26*10 -3 ]]> 183.7 Example 10 2.87 <![CDATA[1.55*10 -2 ]]> 185.8 Example 11 2.90 <![CDATA[4.63*10 -3 ]]> 180.5 Example 12 2.89 <![CDATA[8.95*10 -3 ]]> 182.4 Comparative Example 1 3.04 <![CDATA[1.22*10 -6 ]]> 146.8 Comparative Example 2 1.58 4.38 103.2 Comparative Example 3 1.31 6.37 98.5

[0072] As can be seen from the data in the table above, Example 1 and Figure 1 The XRD results show that a LiVS2 coating layer was successfully synthesized on the surface of Li6PS5Cl using the described method, forming a composite phase. Comparative Example 1 (original Li6PS5Cl) exhibits extremely low electronic conductivity (1.22 × 10⁻⁶). -6 mS / cm), while the electronic conductivity of the materials in all embodiments was significantly improved by orders of magnitude (up to 10 mS / cm), and the electronic conductivity of the materials in all embodiments was significantly improved by orders of magnitude (up to 10 mS / cm). -2 The mS / cm range is as follows, such as 1.55 × 10⁻⁶ in Example 10. -2The ionic conductivity remains at a high level (approximately 2.9-3.0 mS / cm), directly confirming that the present invention successfully endows the sulfide electrolyte with electronic conductivity, achieving the design goal of "hybrid conductivity." Comparing Examples 2 to 5 (V series) and Examples 7 to 10 (Nb series), it can be seen that the electronic conductivity of the composite material increases monotonically with the increase of the metal halide ratio (from 1:100 to 1:10 molar ratio). More importantly, its first-cycle discharge specific capacity also significantly increases (from approximately 172 mAh / g to 185.8 mAh / g), both far exceeding the 146.8 mAh / g of Comparative Example 1, with an increase of over 26%, proving that this hybrid conductor material effectively improves the capacity performance of the cathode. Comparative Examples 2 and 3 used excessive metal halides (molar ratio approximately 1:6.7), resulting in a sharp decrease in their ionic conductivity (down to 1.58 and 1.31 mS / cm, respectively), and a significant reduction in discharge capacity (approximately 100 mAh / g), even far below that of the original electrolyte. This indicates that an excessively thick coating layer hinders lithium-ion transport between the electrolyte cores, disrupting continuous ion channels and negatively impacting battery performance. This result conversely demonstrates the scientific validity and superiority of the molar ratio range (1:100 ~ 1:10) selected in this invention. Examples 1 (V) and 6 (Nb) both successfully prepared high-performance hybrid conductor materials, and the Nb-based material exhibited higher electronic conductivity (compared to 5.21 × 10⁻⁶ mS / cm in Example 1). -3 mS / cm compared to 9.26 × 10 in Example 6 -3 The mS / cm ratio demonstrates the applicability of the method to V, Cr, Fe, Ni, and Nb metals. Examples 11 and 12 attempted to directly use VS2 and NbS2 physically mixed with the electrolyte. While their performance (electronic conductivity and capacity) was better than Comparative Example 1, it was slightly inferior to the corresponding examples (Examples 1 and 6) that used in-situ reactions with metal halides. This indicates that the in-situ reaction method can form a more uniform and tightly bound coating layer, resulting in a better conductive network construction effect.

[0073] This invention successfully constructs a uniform LiMS2 (M=V, Cr, Fe, Ni, Nb) coating layer with mixed conductivity on the surface of sulfide solid electrolyte (such as Li6PS5Cl) particles through in-situ reaction. This design transforms the originally single-function ionic conductor into a "dual-function" conductive unit with excellent ion and electron transport capabilities. When these composite particles are used as conductive media in the cathode of all-solid-state batteries, a continuous and nested ion and electron cooperative transport network can be simultaneously constructed inside the cathode, greatly reducing interfacial transport resistance and solving the fundamental problem of isolated and mutually restrictive ion and electron channels in traditional three-phase hybrid cathodes.

[0074] The positive electrode constructed from the hybrid conductor material prepared in this invention exhibits significantly optimized internal charge transport dynamics and a substantial increase in the utilization rate of active materials. Experimental data show that the first-cycle discharge specific capacity of the positive electrode using this material is increased by more than 20% compared to the positive electrode using the original sulfide electrolyte, effectively improving the energy density and rate performance of the battery.

[0075] Although LiMS2 material itself has low intrinsic ionic conductivity, this invention controls it into an ultrathin nanoscale coating layer, ensuring that its limited ionic conductivity does not significantly hinder overall ion transport dominated by the core sulfide electrolyte. Simultaneously, this layered coating layer still allows lithium ions to pass through, working synergistically with the core to guarantee the continuity of the ion channel. The ball milling and annealing preparation method employed in this invention is simple, requires no complex equipment, and is easily scalable. By precisely controlling process conditions such as the molar ratio of metal halide to electrolyte, ball milling parameters, and annealing temperature, the thickness, uniformity, and crystallinity of the coating layer can be effectively controlled, thereby optimizing the conductivity of the composite material. The process exhibits good repeatability and high reliability.

[0076] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. An electron-lithium ion mixed conductor material, characterized by, Comprise: a sulfide solid-state electrolyte core; a LiMS2 coating layer coated on the surface of the core, wherein M is at least one of V, Cr, Fe, Ni, and Nb.

2. The electronic-lithium ion mixed conductor material of claim 1, wherein, The sulfide solid-state electrolyte is Li 6-X PS 5-X Cl 1+X wherein 0 ≤ x ≤ 0.

6.

3. The electronic-lithium ion mixed conductor material of claim 1, wherein, The thickness of the LiMS2 coating layer is in nanometer level.

4. A method for producing the electronic-lithium ion mixed conductor material according to any one of claims 1 to 3, characterized by, Comprise the following steps: S1, milling a metal halide MX n where M is at least one of V, Cr, Fe, Ni, Nb, X is at least one of F, Cl, Br, I, and 2 ≤ n ≤ 4; S2, ball-milling the metal halide obtained in step S1 and the sulfide solid-state electrolyte in a molar ratio of 1:100-1:10; S3, annealing the mixture obtained in step S2 under an inert atmosphere; S4, ball-milling the product after annealing to obtain the electronic-lithium ion mixed conductor material.

5. The method for preparing an electron-lithium ion hybrid conductor material according to claim 4, characterized in that, The rotation speed of the ball-milling treatment in step S1 is 500-600 rpm, and the time is 20-30 h.

6. The method for preparing an electron-lithium ion hybrid conductor material according to claim 4, characterized in that, The rotation speed of the ball-milling treatment in step S2 is 200-300 rpm, and the time is 5-10 h.

7. The method for preparing an electron-lithium ion hybrid conductor material according to claim 4, characterized in that, The temperature of the annealing treatment in step S3 is 400-500 ℃, the time is 2-5 h, and the inert atmosphere is argon.

8. The method for preparing an electron-lithium ion hybrid conductor material according to claim 4, characterized in that, The rotation speed of the ball-milling in step S4 is 100-200 rpm, and the time is 1-2 h.

9. The method for preparing an electron-lithium ion hybrid conductor material according to claim 4, characterized in that, The molar ratio of the metal halide to the sulfide solid-state electrolyte in step S2 is 1:50-1:

20.

10. The method of claim 4, wherein the electronic-lithium ion mixed conductor material is prepared by the steps of: preparing a precursor material; and sintering the precursor material. The metal halide is at least one of VCl3, NbCl5, FeCl3, NiCl2, and CrCl3.

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