An ultrahigh capacity tellurium-based material with six-electron conversion mechanism and its manganese ion storage applications

Abstract

This invention relates to the field of novel energy storage materials, specifically to an ultra-high capacity tellurium-based material with a six-electron conversion mechanism and its manganese ion storage application. The material system of this invention includes a tellurium-based active material as the working electrode and an ion transport medium adapted to it; wherein the tellurium-based active material is a composite material of tellurium and carbon-based materials; the ion transport medium is a hydrated eutectic system, including manganese salt, hydrogen bond donor water, and hydrogen bond acceptor succinate. This invention successfully activates the deep six-electron conversion reaction (Te6000) of the tellurium-based material in an aqueous environment. 2‑ ↔Te 4+ This breakthrough overcomes the capacity bottleneck of traditional four-electron reactions. The material system not only exhibits excellent conductivity but also demonstrates ultra-high specific capacity and excellent cycle stability, providing a novel material solution for constructing high-specific-energy storage devices.

Description

Technical Field

[0001] This invention relates to the field of novel energy storage materials technology, specifically to an ultra-high capacity tellurium-based material with a six-electron conversion mechanism and its manganese ion storage application. Background Technology

[0002] Aqueous manganese-ion batteries have attracted much attention due to their high safety and low cost. However, water has a narrow electrochemical stability window and a high hydrogen evolution potential, which severely limits energy storage reactions in the low potential range on the negative electrode side. Tellurium has high conductivity and is an ideal energy storage material. However, in conventional aqueous solutions, the electrochemical reactions of tellurium are limited to four-electron redox processes (Te0O ... 0 ↔ Te 4+ Its actual specific capacity is only about 750 mAh g. -1 This is because when the potential is further lowered in an attempt to trigger a higher-capacity conversion reaction, the thermodynamically preferred hydrogen evolution reaction completely blocks the deep reduction pathway of tellurium. Therefore, how to suppress the hydrogen evolution side reaction, thereby overcoming the four-electron reaction bottleneck and achieving the six-electron conversion of tellurium (Te6) is a crucial challenge. 2- ↔ Te 4 + This is a key technical challenge for significantly improving the energy density of manganese-ion batteries.

[0003] In view of this, the present invention provides an ultra-high capacity tellurium-based material with a six-electron conversion mechanism and its manganese ion storage application. The aim is to break through the limitations of traditional four-electron reactions by designing and optimizing the material system, develop a tellurium-based material system that can stably realize the six-electron conversion mechanism, and achieve the goal of significantly improving the energy density of manganese ion energy storage devices. Summary of the Invention

[0004] This invention aims to address the challenges of insufficient capacity utilization, easy solubility, and severe side reactions of existing tellurium-based materials in aqueous energy storage devices, and provides an ultra-high capacity tellurium-based material with a six-electron conversion mechanism and its application system. To this end, this invention reconstructs the microscopic reaction environment on the surface of the tellurium-based material through ligand regulation, successfully unlocking the six-electron conversion pathway of the tellurium-based material, and significantly improving the specific capacity and stability of the material.

[0005] To achieve this objective, the present invention adopts the following technical solution: This invention provides an ultra-high capacity tellurium-based material system with a six-electron conversion mechanism, comprising a tellurium-based active material as a working electrode and an ion transport medium adapted thereto; wherein, the tellurium-based active material is a composite material of tellurium and carbon-based materials; and the ion transport medium is a hydrated eutectic system comprising a manganese salt, hydrogen bond donor water, and hydrogen bond acceptor succinate.

[0006] In this system, the tellurium-based active material can undergo a reversible six-electron redox reaction.

[0007] Furthermore, the molar ratio of water to succinic acid is 3:2-3:7.

[0008] Furthermore, the manganese ion concentration in the hydrated eutectic system ranges from 1 to 2 mol / L.

[0009] Furthermore, the manganese salt includes at least one of manganese perchlorate and manganese bis(trifluoromethanesulfonic acid).

[0010] Furthermore, the tellurium-based active material includes at least one of reduced graphene oxide supported tellurium and porous carbon supported tellurium.

[0011] Furthermore, the preparation method of the tellurium-based active material includes: Step 1: Weigh sodium tellurite, the tellurium precursor, and carbon matrix into deionized water, mix and ultrasonically disperse evenly, then freeze-dry to obtain a dry precursor mixture; Step 2: The precursor mixture is placed in a hydrogen reducing atmosphere for high-temperature annealing at a temperature of 550-650°C for 2-4 hours. Step 3: The annealed product is washed to remove impurities, dried and ground into powder to obtain the tellurium-based electrode material.

[0012] Furthermore, the carbon matrix comprises graphene oxide and / or porous carbon.

[0013] Furthermore, the preparation method of the hydrated eutectic system includes: mixing manganese salt, succinate and water, and treating the mixture under heating conditions until the mixture melts; cooling the mixture to room temperature and stirring until a clear and transparent hydrated eutectic ion transport medium is formed.

[0014] On the other hand, the present invention also provides an application of an ultra-high capacity tellurium-based material system with a six-electron conversion mechanism in an aqueous manganese ion energy storage device.

[0015] The application of the ultra-high capacity tellurium-based material system with a six-electron conversion mechanism in this invention is to construct a three-electron aqueous manganese ion half-cell using the hydrated eutectic solution prepared above. This half-cell system consists of a working electrode, a counter electrode, a reference electrode, a separator, and the aforementioned hydrated eutectic solution. This specific hydrated eutectic medium significantly widens the voltage window of the cell, successfully inducing the six-electron conversion process of the tellurium-based electrode in the manganese ion system.

[0016] The active material of the working electrode is preferably a reduced graphene oxide supported tellurium (Te / rGO) composite material, in which the tellurium loading is 40%-60%, or a porous carbon supported tellurium (Te / C) composite material can also be used.

[0017] The working electrode is prepared by placing the active material (Te / rGO) in a tablet press and pressing it under a pressure of 10~20 MPa to obtain the working electrode sheet.

[0018] The advantages of this invention are: 1. The tellurium-based material system described in this invention successfully achieves a six-electron transfer mechanism, significantly improving its plateau capacity and specific energy density compared to traditional four-electron reactive materials. Specifically, the discharge specific capacity of the working electrode of this invention can reach 800-1050 mAh g⁻¹. -1 Compared to the capacity of the traditional four-electron reaction mechanism (approximately 750 mAh g), -1 The capacity increased by approximately 6.7%-40%.

[0019] 2. This invention fundamentally alters the redox pathway of tellurium by regulating the microenvironment at the material interface, avoiding interference from hydrogen evolution side reactions on material performance, significantly broadening the electrochemical stability window of traditional manganese-ion energy storage batteries, and enabling the reaction potential of the working electrode to safely extend to a lower negative voltage region.

[0020] 3. The hydrated eutectic ion transport medium provides a unique interface protection mechanism. The ligand succinic acid reconstructs the hydrogen bond network of water molecules and optimizes the coordination environment of manganese ions, significantly reducing the content and activity of free water, effectively preventing the dissolution and loss of the working electrode material, so that the tellurium-based material can still maintain a very high capacity retention rate during long-term cycling. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 These are photographs of the phase state changes of the material system prepared in Example 1 of the present invention before and after the medium configuration. Figure 2 This is a differential scanning calorimetry curve of the material system medium obtained in Example 1 of the present invention; Figure 3 This is a comparison of the infrared spectra of the material system media prepared in Example 1 of the present invention; Figure 4 The X-ray diffraction pattern of the tellurium / reduced graphene oxide (Te / rGO) composite, the core active material of this invention; Figure 5 This is a cyclic voltammetry curve of the tellurium-based material described in Embodiment 1 of the present invention; Figure 6 This is the non-in-situ X-ray diffraction pattern of the tellurium-based material of the present invention during the charging and discharging process; Figure 7 This is a comparison diagram of cyclic voltammetry between the tellurium-based material system described in Example 1 and Comparative Example 1 of the present invention and the conventional system; Figure 8 The graphs show the constant current charge-discharge curves of the tellurium-based material system described in Embodiment 1 of the present invention at different current densities. Figure 9 This is a comparison chart of the long-cycle performance of the tellurium-based material system described in Example 1 and Comparative Example 1 of the present invention with that of a conventional system; Figure 10 The tellurium-based material system described in Examples 2 and 3 of this invention is in 0.5 A g -1 Constant current charge-discharge curves at current density; Figure 11 This is a schematic diagram of the mechanism of the ultra-high capacity tellurium-based material system of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0024] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available. Where specific techniques or conditions are not specified in the examples, they can be performed according to the techniques or conditions described in the literature or the product instructions.

[0025] It should also be noted that the manganese perchlorate hexahydrate (purity: Reagent Grade, catalog number: M830894), bis(trifluoromethanesulfonic acid) manganese (purity: 98%, catalog number: M914035), succinic anionyl nitrile (purity: ≥99.7%, catalog number: S874820), and graphene oxide (purity: 99%, catalog number: G931286) used in this invention were all purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Porous carbon (BET: 2000m) 2 g -1(Item No.: 103489) was purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0026] Example 1 The preparation method of the hydrated eutectic solution is as follows: At room temperature, weigh 3.6 g of manganese perchlorate hexahydrate and 8 g of succinic anionizer and place them in a glass bottle, add 270 μL of deionized water; heat at 60 °C for 1 hour to melt and mix them, then cool to room temperature and continue to stir magnetically at 500 rpm for 12 hours to obtain a clear and transparent hydrated eutectic solution; The preparation method of tellurium-based active materials is as follows: Sodium tellurite was weighed as the tellurium source precursor and mixed with graphene oxide at a mass ratio of 7:8 (total mass 2.75 g) in 400 mL of deionized water. After ultrasonic treatment, a uniform dispersion was obtained. Subsequently, the dispersion was subjected to liquid nitrogen freezing and vacuum freeze-drying to obtain a precursor mixture. The dried precursor was placed in a tube furnace, and a hydrogen-argon mixture was introduced and heated to 600 °C for reduction to ensure complete reduction. After cooling, the precursor was washed, dried, and ground to obtain the final reduced graphene oxide-supported tellurium (Te / rGO) composite material.

[0027] The following is the assembly method for an aqueous manganese ion half-cell using the above-mentioned hydrated eutectic solution: For the preparation of the working electrode, the prepared tellurium-based active material was placed in a tableting mold and pressed into a disc with a diameter of 10 mm using a tablet press under a pressure of 20 MPa. The active material loading was controlled between 0.2 and 0.3 mg / cm² to obtain the working electrode sheet.

[0028] For counter electrode preparation, ultra-high capacity porous activated carbon powder was weighed and placed in a pressing mold, and pressed into shape under a pressure of 20 MPa to obtain a counter electrode sheet with a diameter of 10 mm. The activated carbon loading in the electrode sheet was controlled to be greater than 5 mg / cm².

[0029] Using the above-mentioned working electrode, activated carbon counter electrode, and silver chloride reference electrode, along with the hydrated eutectic solution prepared in Example 1, a three-electrode half-cell was assembled using a standard Swagelok mold commonly used in laboratories.

[0030] Example 2 At room temperature, 3.5 g of bis(trifluoromethanesulfonic acid) manganese and 23 g of succinic acid were weighed, and 4 mL of deionized water was added. The same process as in Example 1 was used to obtain a clear and transparent hydrated eutectic solution. Aqueous manganese ion half-cells were assembled using the hydrated eutectic solution of Example 2, with the tellurium-based active material and assembly method being the same as in Example 1.

[0031] Example 3 At room temperature, 3.6 g of manganese perchlorate hexahydrate and 8 g of succinic anionizer were weighed and added to 270 μL of deionized water. A clear and transparent hydrated eutectic solution was obtained using the same process as in Example 1. Tellurium-based active materials were prepared using the process described in Example 1, except that graphene oxide was replaced with porous carbon to obtain a tellurium / porous carbon composite (Te / C). Working electrodes were then prepared using this tellurium-based active material and the process described in Example 1.

[0032] Aqueous manganese ion half-cells were assembled using the hydrated eutectic solution and working electrode of Example 3, and the assembly method was the same as in Example 1.

[0033] Comparative Example 1 At room temperature, 3.6 g of manganese perchlorate hexahydrate was weighed and dissolved in deionized water, and the solution volume was adjusted to 5 mL to prepare a pure aqueous solution with a manganese ion concentration of 2 mol / L. Aqueous manganese ion half-cells were assembled using a pure aqueous solution from Comparative Example 1. The tellurium-based active material and assembly method were the same as in Example 1.

[0034] like Figure 1 and Figure 2 As shown, after the raw material manganese perchlorate is mixed with succinic acid, it transforms from a solid state into a homogeneous, transparent liquid hydrated eutectic solution due to the eutectic effect. Figure 1 DSC differential scanning calorimetry (DSC) Figure 2 This confirms that the system has obvious deep eutectic solvent characteristics, and the solution exhibits a low-temperature glass transition.

[0035] like Figure 3 Infrared spectroscopy revealed that the addition of succinic anion significantly altered the microstructure of the solution. The characteristic peak intensity of water molecules decreased and shifted in the spectrum. This indicates that succinic anion successfully entered the first solvation sheath of manganese ions, reconstructing the coordination environment and effectively suppressing the activity of free water, thus providing a structural basis for broadening the electrochemical stability window.

[0036] like Figure 4 The XRD pattern shows that the prepared Te / rGO composite material clearly displays the characteristic diffraction peaks of tellurium and has no impurity phases, indicating that elemental tellurium has been successfully loaded onto the reduced graphene oxide substrate.

[0037] like Figures 5 to 9 As shown, the Te / rGO electrode exhibits excellent electrochemical performance in the hydrated eutectic electrolyte. Cyclic voltammetry curves ( Figure 5 It exhibits clear multiple pairs of redox peaks, combined with non-in-situ XRD patterns ( Figure 6 As can be seen, tellurium undergoes a wide range of valence states from -2 to +4 during charging and discharging, confirming the six-electron transfer mechanism (Te). 2- ↔ Te 4+This is the fundamental reason why the material achieves ultra-high specific capacity. (Comparison with conventional pure water systems) Figure 7 This further confirms the advantages of the present invention. In pure aqueous solutions, severe hydrogen evolution current exists at low potentials, leading to rapid capacity decay. However, in the hydrated eutectic system of the present invention, the hydrogen evolution reaction is effectively suppressed, the electrochemical window is significantly widened, and the electrode maintains excellent rate performance during long cycles. Figure 8 ) and extremely high stability ( Figure 9 ).

[0038] like Figure 10 As shown, whether the manganese salt anion is replaced (Example 2) or the carbon matrix is ​​changed (Example 3), the system can maintain a similar high-capacity charge-discharge platform, which proves that the six-electron conversion tellurium-based material system has good universality.

[0039] In conclusion, Figure 11 The mechanism diagram summarizes the core advantages of this invention: by introducing succinic acid to regulate the manganese ion solvation structure and reduce the free water content, side reactions were successfully suppressed, unlocking the six-electron deep conversion reaction of tellurium-based materials.

[0040] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate the product and detailed preparation method of the present invention, but the present invention is not limited to the above product and detailed preparation method, that is, it does not mean that the present invention must rely on the above product and detailed preparation method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of excipients, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0041] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention. These simple modifications all fall within the protection scope of the present invention.

[0042] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0043] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A high-capacity tellurium-based material system with a six-electron conversion mechanism, characterized in that, It includes a tellurium-based active material as a working electrode and an ion transport medium adapted thereto; wherein the tellurium-based active material is a composite material of tellurium and carbon materials; and the ion transport medium is a hydrated eutectic system, including manganese salt, hydrogen bond donor water and hydrogen bond acceptor succinate.

2. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 1, characterized in that, The molar ratio of water to succinic anion is 3:2-3:

7.

3. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 1, characterized in that, The manganese ion concentration range of the hydrated eutectic system is 1~2 mol / L.

4. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 1, characterized in that, The manganese salt includes at least one of manganese perchlorate and manganese bis(trifluoromethanesulfonic acid).

5. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 1, characterized in that, The tellurium-based active material includes at least one of reduced graphene oxide supported tellurium and porous carbon supported tellurium.

6. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 5, characterized in that, The preparation method of the tellurium-based active material includes: Step 1: Weigh sodium tellurite, the tellurium precursor, and carbon matrix into deionized water, mix and ultrasonically disperse evenly, then freeze-dry to obtain a dry precursor mixture; Step 2: The precursor mixture is placed in a hydrogen reducing atmosphere for high-temperature annealing at a temperature of 550-650°C for 2-4 hours. Step 3: The annealed product is washed to remove impurities, dried and ground into powder to obtain the tellurium-based electrode material.

7. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 6, characterized in that, The carbon matrix includes graphene oxide and / or porous carbon.

8. The ultra-high capacity tellurium-based material system with a six-electron conversion mechanism according to claim 1, characterized in that, The preparation method of the hydrated eutectic system includes: mixing manganese salt, succinate and water, and treating the mixture under heating conditions until the mixture melts; cooling the mixture to room temperature and stirring until a clear and transparent hydrated eutectic ion transport medium is formed.

9. The application of the ultra-high capacity tellurium-based material system with a six-electron conversion mechanism as described in any one of claims 1-8 in aqueous manganese ion energy storage devices.

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