A thiuram-based lithium battery cathode material rich in electron-deficient structures and a preparation method thereof
The formation of a thiuramyl lithium battery positive electrode material rich in electron-deficient structures in lithium batteries through high-voltage electrochemical oxidation technology has solved the problems of cyclic stability and resource dependence of existing organic sulfur-based materials, and achieved ultra-long cycle performance and good electrochemical performance.
Patent Information
- Application Number
- CN202210885537.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-07-26
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2042-07-26
AI Technical Summary
The existing organic sulfur-based lithium battery cathode materials have shortcomings in molecular dynamics and cycle life, making it difficult to achieve cycle stability of thousands of turns, and their sustainable development is limited due to scarce resource dependence and high-cost catalyst use.
Tetramethylthiuram monosulfide (TMTM) was used as the starting material, and a thiuram lithium battery positive electrode material rich in electron-deficient structure was formed in situ in lithium batteries through high-voltage electrochemical oxidation strategy, and the reaction kinetics and cycle stability were improved using S-S bonds and electron-deficient structures.
The ultra-long cycle performance, good rateability and low temperature characteristics of the lithium battery positive electrode material are achieved, the preparation process is simplified, suitable for industrial production, and significantly improved electrochemical performance.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field of lithium battery cathode materials, and particularly relates to a thiuram-based lithium battery cathode material rich in electron-deficient structures and a preparation method thereof. Background Art
[0002] Due to their high energy density, lithium-ion batteries have been widely used in fields such as portable electronic products and electric vehicles. However, the excessive dependence of lithium-ion battery electrode materials on scarce resources such as cobalt and nickel has hindered their long-term sustainable development in the energy storage field. Based on this, there is an urgent need to develop some sustainable, green and resource-rich energy storage electrode materials. In recent years, organic electrode materials have received increasing attention due to their characteristics such as rich resources and environmental friendliness. As a kind of organic electrode materials, organic sulfur-based cathode materials not only have the advantages of common organic electrode materials, but also have a conversion mechanism similar to that of elemental sulfur.
[0003] Currently, most of the reported organic sulfurs face slow molecular dynamics and limited cycle life, which have seriously hindered their application in commercial batteries. To alleviate these problems, many improvement strategies have been proposed by researchers. For example, introducing catalysts on the electrode to promote the electrochemical conversion of organic sulfur, and obtaining some organic sulfurs with unique molecular structures through chemical synthesis to improve their cycle stability. However, the use of additional catalysts and the complex chemical synthesis process not only greatly increase the cost of the battery, but also these strategies are very limited for improving the molecular dynamics and cycle stability of organic sulfur, and it is difficult to achieve cycle stability of thousands of cycles. As a kind of organic sulfur, tetramethylthiuram monosulfide has not been concerned in the energy storage field because the molecule itself has no active sites. Summary of the Invention
[0004] The purpose of the present invention is to provide a thiuram-based lithium battery cathode material rich in electron-deficient structures and a preparation method thereof. In this lithium battery cathode material, it includes a thiuram recombinant containing S-S bonds and rich in electron-deficient structures. The rich electron-deficient structures can reduce the energy barrier for the cleavage of S-S bonds, thereby promoting the reaction kinetics and cycle stability of organic sulfur in the battery. The obtained lithium battery cathode material exhibits ultra-long cycle performance, good rate performance and low-temperature characteristics in lithium batteries; the preparation method is simple, the reaction is controllable, which is conducive to industrial production.
[0005] To solve the above technical problems, the present invention adopts the following technical solutions:
[0006] Provide a thiuram-based lithium battery cathode material rich in electron-deficient structures, the lithium battery cathode material includes a cathode active material thiuram recombinant; wherein the thiuram recombinant contains S-S bonds and is rich in electron-deficient structures, specifically including the following structures:
[0007]
[0008] According to the above solution, the lithium-ion battery cathode material further includes a cathode substrate carbon paper.
[0009] According to the above solution, the loading of the thiuram recombinant in the cathode material is 0.8 - 4.0 mg cm -2 . Preferably, it is 0.8 - 2.0 mg cm -2 .
[0010] According to the above solution, the cathode material is formed in situ in a lithium battery by a high-voltage electrochemical oxidation strategy using tetramethylthiuram monosulfide (TMTM) as a starting material.
[0011] Provided is a method for preparing a thiuram-based lithium-ion battery cathode material rich in electron-deficient structures, comprising the following steps:
[0012] 1) Using tetramethylthiuram monosulfide (TMTM) as a starting material, dissolving it in an electrolyte solution, and then dropping it onto a carbon paper as the cathode, with the anode being lithium metal, to obtain a lithium-thiuram battery;
[0013] 2) Subjecting the lithium-thiuram battery obtained in step 1) to high-voltage electrochemical oxidation of TMTM to in situ obtain a thiuram-based lithium-ion battery cathode material rich in electron-deficient structures.
[0014] According to the above solution, in step 1), the lithium-thiuram battery further includes a separator. Preferably, the separator is Celgard 2400.
[0015] According to the above steps, in step 1), the electrolyte is an ether-based electrolyte.
[0016] Preferably, the solvent of the electrolyte is a mixed solution of ethylene glycol dimethyl ether and 1,3-dioxolane, and the supporting electrolyte is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3).
[0017] More preferably, the volume ratio of ethylene glycol dimethyl ether to 1,3-dioxolane is 1:0.1 - 1:1; the concentration of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is 0.25 - 4.0 mol / L; the concentration of lithium nitrate (LiNO3) is 0.1 - 0.3 mol / L.
[0018] According to the above steps, in step 1), the ratio of the mass (mg) of TMTM to the volume (μL) of the electrolyte is 1:5 - 1:20; preferably, the ratio of the mass of TMTM to the volume of the electrolyte is 1:10 - 1:20.
[0019] According to the above steps, in step 2), the high voltage is above 3.5 V, and the degree of electrochemical oxidation is 25 - 257 mAh g -1 . During the electrochemical oxidation process, as the reaction proceeds, the charge specific capacity gradually increases, indicating an increase in the degree of electrochemical oxidation.
[0020] Preferably, the high voltage is 3.5 - 4.0 V.
[0021] Preferably, the degree of electrochemical oxidation is 55 - 90 mAh g -1 .
[0022] The beneficial effects of the present invention are as follows:
[0023] 1. The present invention provides a thiuram-based lithium battery cathode material rich in electron-deficient structures, including a cathode active material thiuram recombinant. The thiuram recombinant contains S-S bonds and is rich in electron-deficient structures; among them, the S-S bond is an active site for storing energy, and the presence of the electron-deficient structure can reduce the bond-breaking energy barrier of the S-S bond, thereby accelerating its reaction kinetics in lithium batteries; the obtained thiuram-based lithium battery cathode material rich in electron-deficient structures exhibits ultra-long cycle performance, good rate performance, and low-temperature characteristics in lithium batteries.
[0024] 2. The present invention provides a preparation method for a thiuram-based lithium battery cathode material rich in electron-deficient structures. Using TMTM without electrochemical activity as the starting material and adopting a high-voltage electrochemical oxidation strategy, an electron-deficient structure is formed on the nitrogen of TMTM, promoting the cleavage of the S-C bond on the original TMTM and inducing the recombination of the TMTM molecular structure, in-situ obtaining a thiuram-based lithium battery cathode material containing both S-S bonds and electron-deficient structures. The preparation method is simple, the reaction is controllable, which is conducive to industrial production. The obtained cathode material exhibits ultra-long cycle performance, good rate performance, and low-temperature characteristics, and its electrochemical performance is very excellent, showing significant competitive advantages among commercial cathode materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a process of high-voltage electrochemical oxidation-induced cleavage of the S-C bond of the TMTM molecule in the embodiment of the present invention.
[0026] Figure 2 It is a cyclic performance display diagram of the thiuram-based lithium battery cathode material rich in electron-deficient structures obtained in Example 1 at 10 C.
[0027] Figure 3 It is a rate performance display diagram of the thiuram-based lithium battery cathode material rich in electron-deficient structures obtained in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] The content and method of the present invention will be further described in detail below in conjunction with specific embodiments. Specific implementation manners:
[0029] Example 1
[0030] A preparation method of a thiuram-based lithium battery cathode material rich in electron-deficient structures is provided, including the following steps:
[0031] Take 10 mg of tetramethylthiuram monosulfide (TMTM), and dissolve it in 200 μL of electrolyte. The solvent in the electrolyte is a mixed solution of ethylene glycol dimethyl ether and 1,3-dioxolane with a volume ratio of 1:1, and the electrolyte is 1.0 mol / L LiTFSI and 0.3 mol / L LiNO3. Take 20 μL of the above solution and drop it onto carbon paper with an area of 1.1 cm -2 . Using Celgard 2400 as the separator and lithium as the counter electrode to obtain a lithium-thiuram battery. A thiuram-based lithium battery cathode material rich in electron-deficient structures is obtained by high-voltage electrochemical oxidation of TMTM, with a voltage of 3.5 - 4 V and an electrochemical oxidation degree of 90 mAh g -1 .
[0032] At room temperature of 25 °C and a rate of 10C, when the cathode material is cycled 3000 times, the capacity retention rate reaches 91%, and when cycled 8000 times, the capacity retention rate reaches 70%, corresponding to a capacity decay of 0.0038% per cycle. The cyclic performance display is shown in the appendix Figure 2 , showing excellent long-term cyclic performance.
[0033] At a rate of 20C, the capacity retention rate is 93% of that at 0.5C. The rate performance display is shown in the appendix Figure 3 , indicating that the material has good rate performance.
[0034] In addition, the cathode material can obtain a specific capacity of 125 mAh g -1 at a low temperature of -50 °C and a rate of 0.25C, and the specific capacity has good stability at low temperatures; when cycled 300 times, the capacity retention rate reaches 75%, corresponding to a capacity decay of 0.083% per cycle, fully indicating that the material still maintains redox activity at low temperatures.
[0035] Example 2
[0036] A preparation method of a thiuram-based lithium battery cathode material rich in electron-deficient structures is provided, including the following steps:
[0037] Take 10 mg of TMTM and dissolve it in 200 μL of electrolyte solution. The solvent in the electrolyte solution is a mixed solution of ethylene glycol dimethyl ether and 1,3-dioxolane with a volume ratio of 1:1, and the electrolyte is 1.0 mol / L LiTFSI and 0.3 mol / L LiNO3. Take 20 μL of the above solution and drop it onto a carbon paper with an area of 1.1 cm -2 to obtain a lithium - thiuram battery with Celgard 2400 as the separator and lithium as the counter electrode. Through high - voltage electrochemical oxidation of TMTM, a thiuram - based lithium battery cathode material rich in electron - deficient structures is obtained. The voltage is 3.5 - 4 V, and the degree of electrochemical oxidation is 55 mAh g -1 .
[0038] At room temperature of 25 °C and a rate of 2C, this cathode material is cycled 2000 times, and the capacity retention rate is 75%, corresponding to a capacity decay of 0.0125% per cycle.
[0039] Example 3
[0040] Provide a preparation method of a thiuram - based lithium battery cathode material rich in electron - deficient structures, including the following steps:
[0041] Take 20 mg of TMTM and dissolve it in 200 μL of electrolyte solution. The solvent in the electrolyte solution is a mixed solution of ethylene glycol dimethyl ether and 1,3 - dioxolane with a volume ratio of 1:1, and the electrolyte is 1.0 mol / L LiTFSI and 0.3 mol / L LiNO3. Take 20 μL of the above solution and drop it onto a carbon paper with an area of 1.1 cm -2 to obtain a lithium - thiuram battery with Celgard 2400 as the separator and lithium as the counter electrode. Through high - voltage electrochemical oxidation of TMTM, a thiuram - based lithium battery cathode material rich in electron - deficient structures is obtained. The voltage is 3.5 - 4 V, and the degree of electrochemical oxidation is 90 mAh g -1 .
[0042] At room temperature of 25 °C and a rate of 2C, this cathode material is cycled 1000 times, and the capacity retention rate can reach 80%, corresponding to a capacity decay of 0.02% per cycle.
[0043] Example 4
[0044] Provide a preparation method of a thiuram - based lithium battery cathode material rich in electron - deficient structures, including the following steps:
[0045] Take 40 mg of TMTM and dissolve it in 200 μL of electrolyte solution. The solvent in the electrolyte solution is a mixed solution of ethylene glycol dimethyl ether and 1,3 - dioxolane with a volume ratio of 1:1, and the electrolyte is 1.0 mol / L LiTFSI and 0.3 mol / L LiNO3. Take 20 μL of the above solution and drop it onto a carbon paper with an area of 1.1 cm-2 On the carbon paper, Celgard 2400 was used as the separator and lithium was used as the counter electrode to obtain a lithium-tetrathiamoyl tetramine battery. The tetrathiamoyl tetramine-based lithium battery cathode material rich in electron-deficient structures was obtained by high-voltage electrochemical oxidation of TMTM at a voltage of 3.5 - 4V and an electrochemical oxidation degree of 90 mAh g -1 .
[0046] At room temperature of 25 °C and a rate of 2C, the cathode material was cycled 140 times, and the capacity retention rate could reach 90%, corresponding to a capacity decay of 0.071% per cycle.
Claims
1. A thiuram-based lithium battery cathode material rich in electron-deficient structures, characterized in that, The lithium battery cathode material includes a thiram recombinant as the cathode active material; wherein the thiram recombinant contains S-S bonds and is rich in electron-deficient structures, specifically including the structures , and .
2. The lithium battery cathode material according to claim 1, characterized in that, The lithium-ion cathode material further includes a cathode substrate carbon paper.
3. The lithium-ion battery cathode material according to claim 1, wherein The loading of the thiuram recombinant in the positive electrode material is 0.8 to 4.0 mg cm -2 .
4. A method for preparing a thiuram-based lithium battery cathode material rich in electron-deficient structures according to any one of claims 1-3, characterized in that, It includes the following steps: 1) Using tetramethylthiuram monosulfide as a starting material, dissolving it in an electrolyte solution, and then dropping it onto the carbon paper as the positive electrode, with the negative electrode being lithium metal, to obtain a lithium-tetramethylthiuram battery; 2) Subjecting the lithium-tetramethylthiuram battery obtained in step 1) to high-voltage electrochemical oxidation of tetramethylthiuram monosulfide to in-situ obtain a tetramethylthiuram-based lithium-ion cathode material rich in electron-deficient structures.
5. The preparation method according to claim 4, wherein In step 1), the lithium-tetramethylthiuram battery further includes a separator; the electrolyte solution is an ether-based electrolyte solution.
6. The preparation method according to claim 5, characterized in that, In the ether-based electrolyte solution, the solvent of the electrolyte solution is a mixed solution of ethylene glycol dimethyl ether and 1,3-dioxolane, and the supporting electrolyte is lithium bis(trifluoromethanesulfonyl)imide and lithium nitrate.
7. The preparation method according to claim 4, wherein In step 1), the mass-to-volume ratio of tetramethylthiuram monosulfide to the electrolyte solution is 1 mg:5~20 μL.
8. The preparation method according to claim 7, wherein The mass-to-volume ratio of tetramethylthiuram monosulfide to the electrolyte solution is 1 mg:10~20 μL.
9. The preparation method according to claim 4, characterized in that, In step 2), the high voltage is above 3.5 V, and the degree of electrochemical oxidation is 25~257 mAh g -1 .
10. The preparation method according to claim 9, characterized in that, The high voltage is 3.5 - 4.0 V, and the degree of electrochemical oxidation is 55 - 90 mAh g -1 .