Tellurium positive electrode with high active material ratio, preparation method of tellurium positive electrode and all-solid-state battery

Abstract

The invention belongs to the technical field of solid-state batteries, and provides a high-activity material ratio tellurium positive electrode, a preparation method thereof and an all-solid-state battery. The positive electrode is composed of a tellurium-containing component and a solid electrolyte, and the solid electrolyte is at least partially in an amorphous state and continuously covers the surfaces of tellurium particles to form an electron and ion bicontinuous conduction network; during preparation, electrolyte amorphization and interface bonding are induced through mechanical force such as ball milling; the all-solid-state battery comprises the positive electrode, a solid electrolyte and a lithium-based negative electrode. The structure does not need a conductive agent, the proportion of active substances is greatly increased, interface contact is improved, and transmission impedance is reduced, so that high specific capacity, excellent rate capability and long cycle life are realized.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, specifically relating to a high-activity material tellurium cathode, its preparation method, and an all-solid-state battery. Background Technology

[0002] All-solid-state batteries (ASSBs) are widely considered a key direction for the next generation of energy storage due to their high energy density and inherent safety. Compared to liquid electrolyte systems, solid electrolytes can effectively reduce the risks of leakage and thermal runaway, and allow the use of lithium metal anodes to improve energy density. Among conversion-type cathode materials, chalcogens (sulfur, selenium, and tellurium) have high theoretical capacities. Tellurium, in particular, has potential advantages in achieving high areal capacity and high volumetric energy density batteries due to its high electronic conductivity, high volumetric capacity (approximately 2621 mAh / cm³), and high density.

[0003] However, existing technologies still face the following key challenges: (i) In typical solid-state configurations, poor interfacial contact between tellurium particles and solid electrolytes (such as Li6PS5Cl (LPSC)) hinders electron and lithium-ion transport. Although sulfide electrolytes have high lithium-ion conductivity at room temperature (approximately 10 mS / cm), interfacial mismatch, chemical instability, and mechanical rigidity often lead to interfacial voids and uneven current distribution during cycling; (ii) Solid-state systems lack continuous electron channels, thus generally requiring the addition of conductive carbon, resulting in a decrease in the proportion of active material; (iii) Microstructure instability easily leads to failure behaviors such as interfacial debonding and uneven current distribution. Therefore, developing tellurium-based cathode materials that combine a high proportion of active material with a dual continuous electron-ion transport structure is crucial for improving the performance of all-solid-state lithium-tellurium batteries. Summary of the Invention

[0004] This invention aims to provide a high-activity material tellurium cathode that does not require conductive agents, its preparation method, and an all-solid-state battery. Through mechanical force recombination, the solid electrolyte is at least partially amorphous and continuously coated on the surface of tellurium particles, thereby constructing a dual continuous conductive network of electrons and ions, improving interfacial bonding and enhancing the availability of active materials. This solves the technical problems of existing tellurium-based cathodes, such as reliance on conductive additives, high interfacial transport impedance, low utilization of active materials, and poor cycle stability.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A highly active material tellurium cathode comprises a composite structure of a tellurium-containing component and a solid electrolyte, wherein the solid electrolyte is at least partially amorphous and continuously covers the surface of the tellurium-containing component particles to form a dual continuous conduction network of electrons and ions.

[0006] A further improvement of the present invention is that: Preferably, the solid electrolyte is a halide solid electrolyte and / or a sulfide solid electrolyte.

[0007] Preferably, the halide solid electrolyte is selected from one or more of Li3InCl6, Li2ZrCl6, Li3YCl6, and Li3ErCl6.

[0008] Preferably, the sulfide solid electrolyte is selected from Li6PS5Cl, Li 10 GeP2S 12 Li7P3S 11 One or more of Li3PS4.

[0009] Preferably, it includes 80-95% tellurium and 5-20% solid electrolyte.

[0010] A method for preparing a cathode material according to any one of the above claims includes: mixing a tellurium-containing component with a solid electrolyte component, and using mechanical force to induce the solid electrolyte to form an amorphous coating structure on the surface of tellurium particles, so as to construct a dual continuous conduction network of electrons and ions.

[0011] Preferably, the mechanical force is ball milling, planetary ball milling, vibratory grinding, or mechanochemical treatment.

[0012] Preferably, the tellurium-containing component is in powder form with a particle size of ≤1 micrometer.

[0013] Preferably, the solid electrolyte is in powder form with a particle size of ≤10 micrometers.

[0014] An all-solid-state battery comprising the tellurium-based composite cathode material, solid electrolyte, and a cathode as described in any one of the preceding claims.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a tellurium cathode suitable for all-solid-state batteries. The tellurium cathode contains only elemental tellurium and a solid electrolyte, without the need to add other conductive materials (such as conductive carbon), thereby reducing the heterogeneous transport process in the lithium-ion and electron transport process. In this tellurium cathode, the active material is the main component, with a small amount of solid electrolyte added. The high electronic conductivity of tellurium itself creates a continuous electron channel, while an amorphous electrolyte layer provides a continuous lithium-ion transport path. This solves the problems of poor interfacial contact between tellurium and solid electrolyte, reliance on external carbon materials for electron transport leading to a decrease in the proportion of active material, and capacity decay caused by interfacial debonding during cycling, all without adding any conductive agents. This tellurium cathode reduces actual electrode capacity loss and potential electrochemical failure caused by inactive materials. The resulting tellurium cathode exhibits good overall uniformity with no significant phase separation. Furthermore, the Te-S bonds maintain a strong bond between tellurium and electrolyte, preventing phase separation during cycling. This gives the composite tellurium cathode rapid reaction kinetics and excellent structural stability. This tellurium cathode achieves excellent electrochemical performance while maintaining a high proportion of active cathode material, including theoretical specific capacity, high actual cathode capacity (overall cathode), high rate performance, wide temperature range, and long-term stable cycling.

[0016] This invention also discloses a method for preparing a tellurium cathode suitable for all-solid-state batteries. This method involves ball milling to mix elemental tellurium and a solid electrolyte, resulting in a tellurium cathode with good uniformity and an amorphous electrolyte. The electrolyte and tellurium are no longer in a traditional large-particle physical mixture state, but rather form a dense and homogeneous morphology. This allows the final tellurium cathode to achieve excellent electrochemical performance while maintaining a high proportion of active cathode material, including theoretical specific capacity, high actual cathode capacity (overall cathode), high rate performance, wide temperature range, and long-term stable cycling, which is of great significance to the practical application of solid-state batteries. Attached Figure Description

[0017] Figure 1 The XRD patterns provided in Embodiments 1-3 of this invention; Figure 2 These are scanning electron microscope images provided in Embodiments 4-5 of the present invention; Figure 3 XPS, Te3d spectra of Example 2; Figure 4 Electrochemical performance spectra provided for embodiments 1-3 of the present invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0019] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0020] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0021] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents parts by weight, and "ratio" represents weight proportion.

[0022] The first aspect of the present invention discloses a highly active material tellurium cathode, comprising a composite structure of a tellurium-containing component and a solid electrolyte, wherein the solid electrolyte is at least partially amorphous and continuously covers the surface of the tellurium-containing component particles to form a dual continuous conduction network of electrons and ions.

[0023] The core of this invention lies in constructing a composite cathode system with both structural self-consistency and functional synergy through mechanically driven interface reconstruction: the tellurium-containing component itself serves as the long-range electron transport framework, while the amorphized solid electrolyte achieves atomic-level adhesion and spatially continuous coating at the tellurium particle scale, simultaneously providing localized lithium-ion channels; this cathode, without introducing any conductive carbon, consists only of the tellurium-containing component and the solid electrolyte, forming a high-activity-ratio cathode; through mechanically triggered amorphization and surface coating, the solid electrolyte forms an amorphous capping layer on the tellurium particle surface with controllable thickness, uniform composition, and topological continuity; this capping layer and the tellurium substrate together construct a spatially interpenetrating, functionally complementary electron-ion dual-continuous conduction network.

[0024] In some embodiments of the present invention, the solid electrolyte is a halide solid electrolyte and / or a sulfide solid electrolyte. Specifically, the solid electrolyte can be a halide-only electrolyte, a sulfide-only electrolyte, or a blend of halide and sulfide.

[0025] As one of the preferred options, the solid electrolyte is a sulfide electrolyte. Verification has shown that the sulfide electrolyte can form a tight physical coating and local chemical bond with the nano-tellurium particles during ball milling, thereby improving the interfacial bonding strength and the cross-interfacial migration efficiency of lithium ions. Furthermore, after the sulfide or halide electrolyte is uniformly dispersed in the tellurium matrix, it can form a through-type ion permeation network at the nanoscale.

[0026] As one of the preferred options, the solid electrolyte is a blend of halides and sulfides. Halides and sulfides have different mechanical response behaviors. Sulfides are more prone to amorphization, while halides are more resistant to oxidation. This allows the composite electrolyte system to meet the plastic deformation capacity required for coating and film formation, while also taking into account the interfacial thermodynamic stability under high voltage conditions.

[0027] In some embodiments of the present invention, the halide solid electrolyte is at least one of Li3InCl6, Li2ZrCl6, Li3YCl6, and Li3ErCl6.

[0028] In some embodiments of the present invention, the sulfide solid electrolyte is selected from Li6PS5Cl, Li 10 GeP2S 12 Li7P3S 11 At least one of Li3PS4.

[0029] In some embodiments of the present invention, the electrode comprises 80-95% tellurium and 5-20% solid electrolyte by mass fraction. This composition further defines the specific ratio range of tellurium to solid electrolyte in the high-activity-to-tellurium cathode, maximizing the high capacity advantage while providing the necessary ion conduction pathway through the 5-20% solid electrolyte. This allows the electrode to achieve full utilization of the active material even without carbon addition, solving the problem of low capacity or short cycle life caused by electrolyte / active material imbalance in traditional cathodes. A preferred embodiment comprises 89-91% tellurium and 9-11% solid electrolyte.

[0030] A second aspect of this invention discloses a method for preparing the aforementioned active material tellurium-containing cathode, comprising the following steps: mixing a tellurium-containing component with a solid electrolyte component, and using mechanical force to induce the solid electrolyte to form an amorphous coating structure on the surface of tellurium particles, thereby constructing a dual continuous electron and ion conduction network. During this process, through mechanical force treatment, elemental tellurium participates in the composite process in the form of nanoscale powder, possessing a high specific surface area and strong surface activity, which is beneficial for interfacial interaction with the solid electrolyte under mechanical force. This mechanical mixing process, with the aid of mechanical force, allows sulfides to combine with elemental tellurium, enabling the sulfide solid electrolyte to possess both ion transport channel construction and interfacial chemical anchoring functions.

[0031] During the mixing process, dynamic reconstruction occurs under mechanochemical action: the tellurium particle surface undergoes slight lattice distortion and releases active sites, which then combine to form Te-S or Te-Cl bonds. The electrode formed by this method benefits from the excellent intrinsic electronic conductivity and reversible lithiation reaction of tellurium itself, while the solid electrolyte, after mechanical mixing, not only provides Li- but also... + The transport channels anchor tellurium particles through interfacial bonding, suppressing aggregation and detachment during cycling. Therefore, the integrity of the overall conductive network of the electrode can be maintained without additional conductive additives. Furthermore, because tellurium has high activity and can combine well with solid electrolytes, the interfacial impedance between the two is reduced, improving the lithium-ion conductivity. This results in a significant increase in the absolute amount of active material per unit mass of the cathode, and an increase in the actual specific capacity of the cathode.

[0032] It should be understood that the amorphous coating structure refers to the solid electrolyte undergoing lattice distortion, bond breakage and rearrangement under mechanical force, losing its long-range ordered crystal structure and transforming into an amorphous state with short-range order and long-range disorder. The diffraction peaks of the corresponding electrolyte in the XRD pattern completely disappear (as shown in Example 3), while the characteristic peaks of tellurium are still clearly retained, confirming the selective amorphization of the electrolyte.

[0033] On the other hand, the SEM image of the final cathode material shows that the final material has good uniformity, and the two-phase structure is not visible at a certain magnification, exhibiting a homogeneous overall characteristic. This indicates that the two phases are mixed uniformly and composited in a more uniform and finer state. The preparation method of this invention, under normal temperature and pressure conditions, relies solely on controllable mechanical force input to complete the transition from macroscopic mixing of tellurium and solid electrolyte to nanoscale interface reconstruction; the amorphous electrolyte coating layer not only serves as Li + The transport medium anchors tellurium particles through Te–S or Te–Cl chemical bonds, inhibiting interfacial debonding and aggregation of active materials during cycling; the tellurium particles themselves form a continuous electronic framework, eliminating dependence on external conductive agents.

[0034] In some embodiments of the present invention, the mechanical force is ball milling, planetary ball milling, vibratory grinding, or mechanochemical treatment.

[0035] For example, the rotational speed during ball milling or planetary ball milling is 250-400 rpm, and the milling time is 1-3 hours. The ball milling process uses mechanical ball milling technology to apply continuous and controllable mechanical energy input to the premixed powder, promoting the physicochemical co-evolution of tellurium and the solid electrolyte under solid-state conditions. The ball milling equipment is a planetary ball mill, and the grinding media is a high-hardness inert material, such as zirconia balls or tungsten carbide balls; the specific ball-to-powder ratio can be adjusted according to actual conditions, for example, 10:1 to 40:1. Controlling the ball milling speed at 250-400 rpm provides sufficient impact energy to drive interface reconstruction while avoiding local overheating and decomposition; the milling time is controlled at 1-3 hours. Too short a time results in insufficient amorphization and uneven dispersion, while too long a time may induce abnormal tellurium grain growth or excessive electrolyte decomposition.

[0036] In some embodiments of the present invention, the tellurium is in powder form with a particle size of 5-20 nanometers, more preferably 5-20 nanometers.

[0037] In some embodiments of the present invention, the solid electrolyte is in powder form with a particle size not exceeding 10 micrometers, more preferably 1-5 micrometers. The present invention controls tellurium to the nanoscale and the solid electrolyte to the micrometer scale. Under ball milling, the micrometer-sized electrolyte particles are gradually broken and amorphized by shear and impact forces, and are interleaved with highly active nano-tellurium particles, thereby constructing a composite structure with a continuous electronic conductivity network and interconnected ion channels. This multi-scale synergistic design avoids the interfacial debonding or transport bottleneck problems caused by large differences in the physical properties between components in traditional electrodes.

[0038] This invention also discloses an all-solid-state battery, comprising the aforementioned high-activity-ratio tellurium positive electrode, solid electrolyte, and negative electrode. By physically stacking and interfacially coupling the high-activity-ratio, built-in dual-continuous conduction network of the positive electrode with a matching solid electrolyte layer and a high-capacity negative electrode, a solid-state electrochemical device with a complete charge transport path is formed. The tellurium-based composite positive electrode material itself integrates an electronic conduction framework (composed of tellurium particles in contact) and ion conduction channels (provided by the amorphous solid electrolyte coating layer), eliminating the need for additional conductive additives or binders. The powdered tellurium positive electrode can be cold-pressed into electrode sheets for use. The solid electrolyte, as the lithium-ion selective transport medium between the positive and negative electrodes, must maintain compatibility in chemical composition, phase state, and interfacial compatibility with the solid electrolyte components in the positive electrode. For example, when the positive electrode is halide-based, a homologous halide solid electrolyte can be used. The cathode can be a sulfide-based electrolyte (such as Li3InCl6) to ensure the thermodynamic stability of the interface; when the cathode is sulfide-based, a sulfide solid electrolyte (such as Li6PS5Cl) can be used to achieve a low-resistance solid-solid interface; when the cathode includes both sulfides and halides, the solid electrolyte can be either a sulfide or a sulfide; the anode can be any one of lithium metal, lithium indium alloy or lithium silicon alloy, where lithium metal anode can maximize the energy density of the battery, while lithium indium alloy can maintain a high lithium-ion mobility while suppressing dendrite growth.

[0039] Furthermore, the negative electrode is an electrode assembly that provides a lithium source and participates in the electrochemical reaction, and its form is not limited to foil or sheet.

[0040] The technical solution of this patent will be described in detail below with reference to specific embodiments and accompanying drawings. These embodiments do not constitute a limitation on this patent. It should be understood that, due to the inherent error in microscopic dimensions, the particle sizes of the raw materials used below are all approximate values.

[0041] Example 1 A lithium tellurium cathode with ultra-high positive electrode activity material ratio comprises the following components by mass percentage: 80% tellurium, 20% Li6PS5Cl solid electrolyte, ball milled at 250 rpm for 1 hour, with tellurium particle size of approximately 100 nanometers and electrolyte size of approximately 5 micrometers.

[0042] Example 2 A lithium tellurium cathode with ultra-high positive electrode activity material ratio comprises the following components by mass percentage: 90% tellurium, 10% Li6PS5Cl solid electrolyte, ball milled at 350 rpm for 2 hours, with tellurium particle size of approximately 10 nanometers and electrolyte size of approximately 2 micrometers.

[0043] See Figure 1XPS spectra of the material prepared for this embodiment were obtained. As can be seen from the figures, the prepared XPS spectra show new characteristic peaks compared to the original tellurium, mainly composed of Te-S bonds. This indicates that tellurium and LPSC are no longer simply physically mixed, but have formed chemical bonds. The formation of chemical bonds can promote a stronger bond between tellurium and LPSC, preventing phase separation during discharge electrochemistry due to volume changes, etc.

[0044] Example 3 A lithium tellurium cathode with ultra-high positive electrode activity material ratio comprises the following components by mass percentage: 95% tellurium, 5% Li6PS5Cl solid electrolyte, ball milled at 400 rpm for 3 hours, with tellurium particle size of approximately 50 nanometers and electrolyte size of approximately 5 micrometers.

[0045] The XRD pattern of the solid electrolyte after ball milling is shown below. Figure 2 As shown, from Figure 2 As can be seen from the XRD, the ball-milled sample only shows the characteristic peaks of tellurium, and no longer shows the characteristic peaks of LPSC, proving that LPSC has become amorphous. Amorphous LPSC can be more uniformly dispersed around tellurium to achieve better contact and more uniform properties.

[0046] See Figure 4 The electrochemical test results for Examples 1-3 are shown in Figure (a). Figure (a) shows that Examples 1-3 all achieved high specific capacities, especially Example 2, which achieved a specific capacity of 420 mAh / g, reaching its theoretical specific capacity. Figure (b) shows that at a high rate of 2C, Examples 1-3 all exhibited good cycling stability and maintained high specific capacities.

[0047] Example 4 A lithium-tellurium cathode with ultra-high cathode activity comprises the following components by mass percentage: tellurium 90%, Li 10 GeP2S 12 Solid electrolyte 10%, ball milling speed 350 rpm, 2 hours, tellurium particle size about 50 nanometers, electrolyte about 5 micrometers.

[0048] Example 5 A lithium tellurium cathode with ultra-high positive electrode activity material ratio comprises the following components by mass percentage: 90% tellurium, 10% Li3InCl6 solid electrolyte, ball milled at 350 rpm for 2 hours, with tellurium particle size of approximately 50 nanometers and electrolyte size of approximately 5 micrometers.

[0049] See Figure 4 The SEM images corresponding to Examples 4 and 5 show that the prepared composite exhibits a homogeneous characteristic. Tellurium and LPSC electrolyte are no longer a two-phase mixture of large particles, but a composite in a more uniform and finer state.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly active material tellurium-specific cathode, characterized in that, The composite structure includes a tellurium-containing component and a solid electrolyte, wherein the solid electrolyte is at least partially amorphous and continuously covers the surface of the tellurium-containing component particles to form a dual continuous conduction network of electrons and ions.

2. The cathode material according to claim 1, characterized in that, The solid electrolyte is a halide solid electrolyte and / or a sulfide solid electrolyte.

3. The cathode material according to claim 2, characterized in that, The halide solid electrolyte is selected from one or more of Li3InCl6, Li2ZrCl6, Li3YCl6, and Li3ErCl6.

4. The cathode material according to claim 2, characterized in that, The sulfide solid electrolyte is selected from Li6PS5Cl, Li 10 GeP2S 12 Li7P3S 11 One or more of Li3PS4.

5. The positive electrode material according to claim 1, characterized in that, It comprises 80-95% tellurium and 5-20% solid electrolyte by mass fraction.

6. A method for preparing the cathode material according to any one of claims 1-5, characterized in that, include: The tellurium-containing component is mixed with the solid electrolyte component, and mechanical force is used to induce the solid electrolyte to form an amorphous coating structure on the surface of the tellurium particles, so as to construct a dual continuous conduction network of electrons and ions.

7. The preparation method according to claim 6, characterized in that, The mechanical force is ball milling, planetary ball milling, vibratory grinding, or mechanochemical treatment.

8. The preparation method according to claim 6 or 7, characterized in that, The tellurium-containing component is in powder form with a particle size of ≤1 micrometer.

9. The preparation method according to claim 6 or 7, characterized in that, The solid electrolyte is in powder form with a particle size of ≤10 micrometers.

10. An all-solid-state battery, characterized in that, It includes the tellurium-based composite cathode material, solid electrolyte, and anode as described in any one of claims 1-9.

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