A rechargeable lithium thionyl chloride battery cathode material and its preparation method, and a rechargeable lithium thionyl chloride battery and its preparation method.

Abstract

This invention belongs to the field of rechargeable battery technology, and discloses a rechargeable lithium thionyl chloride battery positive electrode material and its preparation method, as well as a rechargeable lithium thionyl chloride battery and its preparation method. The rechargeable lithium thionyl chloride battery positive electrode material is obtained by carbonizing phenolic resin and activating it at high temperature with carbon dioxide to obtain a phenolic resin-based porous carbon material with a nitrogen atom doped structure. The rechargeable lithium thionyl chloride battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a current collector and the phenolic resin-based porous carbon material attached to the current collector. The electrolyte is a thionyl chloride solution containing chlorides and fluorides. The rechargeable lithium thionyl chloride battery of this invention has a maximum cycle specific capacity of up to 6000 mAh / g and a maximum current density of up to 1500 mA / g, both higher than existing similar batteries. Furthermore, it exhibits excellent cycle stability and has excellent theoretical and practical prospects.

Description

Technical Field

[0001] This invention belongs to the field of rechargeable battery technology, and relates to a rechargeable lithium thionyl chloride battery cathode material and its preparation method, as well as a rechargeable lithium thionyl chloride battery and its preparation method. Background Technology

[0002] With the development of industrial production and technology, energy is becoming increasingly important in people's lives. However, the global energy shortage problem is worsening, and the demand for green and renewable energy is constantly increasing. In renewable energy storage research, electrochemical energy storage systems, especially rechargeable batteries, occupy a dominant position, with lithium-ion batteries (LIBs) being the most widely used. However, LIBs have significant limitations in applications such as electric vehicles and grid energy storage due to their limited energy density. Therefore, designing new battery concepts with high specific capacity and high energy density is of great significance for meeting the growing energy storage needs of society.

[0003] Lithium thionyl chloride (Li / SOCl2) batteries are renowned for their high energy density (>700 W·h / kg), as well as their high open-circuit voltage (greater than 3.6 V) and wide operating temperature range (-60 to 150 °C). They are widely used in primary batteries. The emerging rechargeable Li / Cl2 battery, based on the Li / SOCl2 primary battery, achieves rechargeability through a reversible LiCl / Cl2 redox reaction (Zhu G, Tian X, Tai H C, et al. Rechargeable Na / Cl2 and Li / Cl2 batteries[J]. Nature, 2021, 596(7873):525-530.). Rechargeable Li / SOCl2 batteries inherit the performance advantages of Li / SOCl2 primary batteries, showing great promise for manufacturing high-energy rechargeable batteries using liquid / gas materials, and are expected to become the most attractive product in the next generation of rechargeable battery systems.

[0004] Rechargeable Li / SOCl2 batteries consist of a metallic Li anode, a porous cathode, and an SOCl2-based electrolyte. These batteries are still in the early stages of research and development, and the development of various cathode materials has been the primary research focus to date. Currently, the high specific capacity cycling performance of rechargeable Li / SOCl2 batteries using carbon cathodes still needs improvement. A major reason for battery failure at high cycle capacity is the weak interaction between the cathode material and Cl2 molecules, resulting in insufficient Cl2 supply during electrochemical reactions. This limits the high specific capacity cycling performance and also reduces the battery's energy density (Xu Y, Zhang S, Wang M, et al. Enrichment of Chlorine in Porous Organic Nanocages for High-Performance Rechargeable Lithium–Chlorine Batteries[J]. Journal of the American Chemical Society, 2023, 145(50): 27877-27885.). In addition, the cycle current density of rechargeable Li / SOCl2 batteries using carbon material cathodes is also poor, which should be due to the slow reaction kinetics of LiCl / Cl2 at the cathode (Xu Y,Jiao L,Ma J,et al.Metal-organic frameworks for nanoconfinementofchlorine in rechargeable lithium-chlorine batteries[J].Joule,2023,7(3):515-528.).

[0005] Previous studies have shown that nitrogen doping on carbon materials can significantly modulate the adsorption of Cl2 by carbon materials and enable rechargeable Na / Cl2 batteries to achieve rapid NaCl / Cl2 conversion kinetics (Xiang L, Xu Q, Zhang H, et al. Ultrahigh-Rate Na / Cl2 Batteries Through Improved Electron and Ion Transport by Heteroatom-Doped Bicontinuous-Structured Carbon[J]. Angewandte Chemie International Edition, 2023, 62(47):e202312001.). Since Na and Li are both alkali metals with similar chemical properties, and Na / Cl2 batteries and Li / Cl2 batteries have highly similar reaction mechanisms, theoretically, by adjusting the chemical composition of porous carbon, it should also be possible to enhance the adsorption of Cl2 and the LiCl / Cl2 reaction kinetics in rechargeable Li / SOCl2 batteries, thereby improving the specific capacity and current density of rechargeable Li / SOCl2 batteries, and thus promoting the development of cathode materials for rechargeable Li / SOCl2 batteries. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the present invention provides a rechargeable lithium thionyl chloride battery cathode material and a corresponding rechargeable lithium thionyl chloride battery, as well as a method for preparing the cathode material. The cathode material has a nitrogen atom doped structure and has abundant reactive sites. The rechargeable lithium thionyl chloride battery assembled therefrom has advantages such as high capacity and high rate, and has extremely promising prospects for practical applications.

[0007] The technical solution of this invention:

[0008] A rechargeable lithium thionyl chloride battery cathode material is a phenolic resin-based porous carbon material with a nitrogen atom doped structure obtained by carbonization and high-temperature activation of phenolic resin with carbon dioxide. The phenolic resin is synthesized from a bio-based triphenol compound containing an aryl triazine ring structure and formaldehyde. The bio-based triphenol compound containing an aryl triazine ring structure is synthesized from vanillin through a two-step reaction.

[0009] A method for preparing a positive electrode material for a rechargeable lithium thionyl chloride battery, comprising the following steps:

[0010] S11. A bio-based triphenol compound containing an aryl triazine ring structure is reacted with a 37wt% formaldehyde solution in a nitrogen or argon atmosphere at pH 8-11 at 80-100℃ for 8-12 hours. The reaction product is settled in deionized water, the pH of the system is adjusted to 5, and the mixture is filtered. The filter cake is cured at 120-200℃ for 2-6 hours to obtain phenolic resin, which serves as a precursor for porous carbon materials.

[0011] S12. Place the prepared phenolic resin into a tube furnace, introduce nitrogen or argon gas at a flow rate of 20-50 ml / min, heat to 500-800℃ at a rate of 5-10℃ / min and hold for carbonization for 1-3 hours to obtain phenolic resin-based carbon material. Then, introduce carbon dioxide at a flow rate of 20-50 ml / min into the tube furnace, heat the phenolic resin-based carbon material to 800-1200℃ at a rate of 5-10℃ / min and hold for activation for 0.5-1.5 hours to obtain phenolic resin-based porous carbon material. The phenolic resin-based porous carbon material is used as a positive electrode material for rechargeable lithium thionyl chloride batteries.

[0012] The bio-based triphenol compound containing an aryl triazine ring structure is a synthetic product disclosed by the inventors in a previously published paper. The specific preparation method can be found in the following paper: Qi Y, Weng Z, Kou Y, et al. Synthesize and introduce bio-based aromatic s-triazine in epoxy resin: Enabling extremely high thermal stability, mechanical properties, and flame etardancy to achieve high-performance sustainable polymers[J]. Chemical Engineering Journal, 2021, 406: 126881.

[0013] A rechargeable lithium thionyl chloride battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode includes a current collector and a positive electrode material attached to the current collector, and the electrolyte is a thionyl chloride solution containing chloride and fluoride.

[0014] The current collector is made of nickel foam, carbon cloth, or stainless steel mesh.

[0015] The chlorides in the electrolyte include aluminum chloride and / or lithium chloride.

[0016] The fluorides in the electrolyte include lithium bis(fluorosulfonyl)imide and / or lithium bis(trifluoromethanesulfonyl)imide.

[0017] The concentration of chloride in the electrolyte is 1-3 mol / L.

[0018] The electrolyte contains fluoride at a mass of 2-4 wt% of the total mass of thionyl chloride and chloride.

[0019] A method for preparing a rechargeable lithium thionyl chloride battery, comprising the following steps:

[0020] Preparation of the positive electrode: A dispersion of the positive electrode material for a rechargeable lithium thionyl chloride battery is added to a current collector and dried to obtain the positive electrode;

[0021] Preparation of electrolyte: Chloride is added to thionyl chloride, and then fluoride is added to obtain electrolyte;

[0022] Provides a negative electrode and a separator, and assembles the positive electrode, negative electrode, separator and electrolyte to obtain a rechargeable lithium thionyl chloride battery.

[0023] The preparation of the positive electrode includes the following steps:

[0024] S21. A dispersion of rechargeable lithium thionyl chloride battery positive electrode material, conductive agent and binder is obtained by ultrasonication in anhydrous ethanol at a certain mass ratio; wherein, the conductive agent is Ketjen black, acetylene black or conductive carbon black, the binder is 60wt% polytetrafluoroethylene concentrated dispersion, and the mass ratio of positive electrode material: conductive agent: binder is 6-8:3-1:1.

[0025] S22. Provide a current collector, add the dispersion droplets onto the current collector and dry them to prepare a positive electrode;

[0026] The preparation of the electrolyte includes the following steps:

[0027] S31. Add aluminum chloride to thionyl chloride at a concentration of 1-3 mol / L and stir for 10-60 min. Then add lithium chloride to the solution at a concentration slightly higher than that of aluminum chloride and stir for 10-60 min, or do not add lithium chloride. After this step, the first solution is formed.

[0028] S32. Add at least one of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide to the first solution, with the amount of fluoride added being 2-4 wt% (based on the total mass of thionyl chloride and chloride), stir for 0.5-8 h, and then let stand for 8-24 h before taking the supernatant to obtain the electrolyte.

[0029] The preparation of the rechargeable lithium thionyl chloride battery includes:

[0030] The negative electrode is lithium metal, the separator is either a glass fiber separator or a polymer separator, and the electrolyte addition amount is 50-150 microliters.

[0031] The beneficial effects of this invention are:

[0032] 1. The phenolic resin-based porous carbon material provided by the present invention uses widely available biomass vanillin to prepare the resin. The raw materials are green and sustainable. The resin carbonization and CO2 high-temperature activation process is simple and clean, requires no post-processing, and is suitable for large-scale production.

[0033] 2. The rechargeable lithium thionyl chloride battery assembled in this invention has a maximum cycle capacity of up to 6000 mAh / g, which is higher than that of existing similar battery technology literature.

[0034] 3. The rechargeable lithium thionyl chloride battery assembled in this invention has a maximum current density of up to 1500 mA / g, which is higher than that in existing literature on similar battery technologies. Attached Figure Description

[0035] Figure 1 The above are X-ray photoelectron spectroscopy (XPS) spectra of the phenolic resin-based porous carbon material in Example 1 of this invention; where (a) is the C1s XPS spectrum and (b) is the N1s XPS spectrum.

[0036] Figure 2 This is a comparison chart of the battery cycle test performance of battery sample 1 and battery sample 2 in Example 3 of the present invention at a cycle specific capacity of 2500 mAh / g and a current density of 1000 mA / g.

[0037] Figure 3 This is a battery cycle test diagram of battery sample 1 in Example 3 of the present invention at 1000mAh / g and different current densities;

[0038] Figure 4 This is a battery cycle test diagram of battery sample 1 in Example 3 of the present invention at a current density of 500 mAh / g and different cycle specific capacities. Detailed Implementation

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0040] Example 1:

[0041] Cathode materials and their preparation

[0042] (1) A bio-based triphenol compound containing an aryl triazine ring structure was reacted with 37wt% formaldehyde solution at 90℃ for 8h in an environment of pH=10. The reaction product was precipitated in deionized water. The pH of the system was adjusted to 5, filtered, and the filter cake was cured at 140℃ for 2h to obtain phenolic resin (BPT) as a precursor.

[0043] (2) The prepared phenolic resin was carbonized at 600°C for 2 hours under a nitrogen or argon atmosphere with a gas flow rate of 50 ml / min to obtain phenolic resin-based carbon material (BRC). The BRC was activated at 1000°C for 0.5 hours under a carbon dioxide atmosphere with a gas flow rate of 20 ml / min to prepare phenolic resin-based porous carbon material (BRPC-CO2). The phenolic resin-based porous carbon material is used as the positive electrode material of rechargeable lithium thionyl chloride battery.

[0044] (3) Mix 60 mg of phenolic resin-based porous carbon material (BRPC-CO2), 30 mg of Ketjen black (KJ) and 10 mg of polytetrafluoroethylene (PTFE) in 10 ml of anhydrous ethanol and sonicate to obtain a dispersion.

[0045] (4) The dispersion is added dropwise onto the nickel foam and dried to prepare the positive electrode.

[0046] Figure 1 The X-ray photoelectron spectrum of the phenolic resin-based porous carbon material (BRPC-CO2) in this embodiment is shown. Figure 1 It can be seen that the activated BRPC-CO2 sample has a nitrogen atom doped structure, with the nitrogen doping structures being pyrrole nitrogen, pyridine nitrogen, and graphitic nitrogen.

[0047] Comparative Example 1

[0048] Cathode materials and their preparation

[0049] (1) A bio-based triphenol compound containing an aryl triazine ring structure was reacted with 37wt% formaldehyde solution at 90℃ for 8h in an environment of pH=10. The reaction product was precipitated in deionized water. The pH of the system was adjusted to 5, filtered, and the filter cake was cured at 140℃ for 2h to obtain phenolic resin (BPT) as a precursor.

[0050] (2) The prepared phenolic resin was carbonized at 600°C for 2 hours under a nitrogen or argon atmosphere with a gas flow rate of 50 ml / min to obtain phenolic resin-based carbon material (BRC), which was used as the positive electrode material of rechargeable lithium thionyl chloride battery.

[0051] (3) Mix 60 mg of phenolic resin-based carbon material (BRC), 30 mg of Ketjen black (KJ) and 10 mg of polytetrafluoroethylene (PTFE) in 10 ml of anhydrous ethanol and sonicate to obtain a dispersion.

[0052] (4) The dispersion is added dropwise onto the nickel foam and dried to prepare the positive electrode.

[0053] Two types of positive electrodes were prepared as described above: one type uses BRPC-CO2, a phenolic resin-based porous carbon material that has been activated by CO2 at high temperature, as the positive electrode material. The dispersion of BRPC-CO2 is dropped onto nickel foam and dried to prepare the positive electrode, hereinafter referred to as positive electrode BRPC-CO2, as Example 1; the other type uses BRC, a phenolic resin-based carbon material that has not been activated by CO2 at high temperature (only the CO2 high-temperature activation step is removed, and the remaining steps are the same as in Example 1), as the positive electrode material. The dispersion of BRC is dropped onto nickel foam and dried to prepare the positive electrode, hereinafter referred to as positive electrode BRC, as Comparative Example 1.

[0054] Example 2:

[0055] Preparation of electrolyte

[0056] (1) Add aluminum chloride at 2 mol / L to thionyl chloride and stir for 30 min. Then add lithium chloride at 2.05 mol / L to the solution and stir for 60 min. After the first solution is formed, the first solution is formed.

[0057] (2) Add lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide to the first solution. The amount of each fluoride added is 2wt% (based on the total mass of thionyl chloride and chloride). Stir for 8 hours, then let stand for 12 hours and take the supernatant to obtain the electrolyte.

[0058] Example 3:

[0059] Electrochemical testing of rechargeable lithium thionyl chloride batteries

[0060] A rechargeable lithium thionyl chloride battery is described. It should be noted that in this embodiment, the positive electrode and electrolyte prepared above are assembled to form a rechargeable lithium thionyl chloride battery for relevant electrochemical performance testing.

[0061] Specifically, the positive electrode prepared in Example 1 was used as the working electrode, the electrolyte was the electrolyte prepared in Example 2 with an electrolyte addition amount of 150 μL, the separator was a GF / D glass fiber separator, lithium metal was used as the counter electrode (negative electrode), and a CR2032 battery case was used to assemble a coin cell for electrochemical performance testing.

[0062] Battery Sample 1: The working electrode is the positive electrode BRPC-CO2 prepared in Example 1, the electrolyte is the electrolyte prepared in Example 2, the counter electrode is lithium metal, and the separator is a GF / D glass fiber separator.

[0063] Battery Sample 2: The working electrode is the positive electrode BRC prepared in Comparative Example 1, the electrolyte is the electrolyte prepared in Example 2, the counter electrode is lithium metal, and the separator is a GF / D glass fiber separator.

[0064] Figure 2 This is a comparison chart of the battery cycle performance of battery sample 1 and battery sample 2 in the above embodiments at a cycle specific capacity of 2500 mAh / g and a current density of 1000 mA / g. From... Figure 2 As can be seen from the results, the BRPC-CO2 cathode provided by this invention exhibits better cycle stability than the BRC cathode under the same test conditions, indicating that the BRPC-CO2 cathode has good Cl2 adsorption capacity and abundant LiCl / Cl2 reactive sites. The battery can maintain a stable cycle capacity of 2500mAh / g for 180 cycles at a current density of 1000mA / g, with the average coulombic efficiency maintained at 100%.

[0065] Figure 3 This is a battery cycle test graph showing the cycle specific capacity of battery sample 1 in the above embodiments at 1000 mAh / g and under different current densities. From Figure 3 As can be seen from the above, the positive electrode BRPC-CO2 provided by the present invention achieves a maximum cycle capacity of 6000mAh / g at a current density of 500mA / g.

[0066] Figure 4 This is a battery cycle test graph of battery sample 1 in the above embodiments at a current density of 500 mAh / g and different cycle specific capacities. From Figure 4 As can be seen from the above, the positive electrode BRPC-CO2 provided by the present invention achieves a maximum current density of 1500mA / g at a cycle capacity of 1000mAh / g.

[0067] In summary, in this embodiment of the invention, a phenolic resin-based porous carbon material with a nitrogen atom doped structure is obtained by carbonizing phenolic resin and activating it at high temperature with carbon dioxide as the positive electrode material of a rechargeable lithium thionyl chloride battery. It has good Cl2 adsorption capacity and abundant LiCl / Cl2 reactive sites. The rechargeable lithium thionyl chloride battery assembled therefrom has extremely high cycle specific capacity and cycle current density.

[0068] To better illustrate the outstanding advantages of this invention, the maximum cycle specific capacity and maximum current density of rechargeable lithium thionyl chloride batteries (or rechargeable lithium chlorine batteries) at room temperature, as described in existing literature on similar battery technologies, are summarized in the table below for comparison:

[0069]

[0070] The above description is only a preferred embodiment of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a positive electrode material for a rechargeable lithium thionyl chloride battery, characterized in that, The positive electrode material of this rechargeable lithium thionyl chloride battery is a phenolic resin-based porous carbon material with a nitrogen atom doped structure, obtained by carbonization and high-temperature activation of phenolic resin with carbon dioxide. The phenolic resin is synthesized from a bio-based triphenol compound containing an aryl triazine ring structure and formaldehyde. The preparation method described herein comprises the following steps: S11. A bio-based pyrogallol compound containing an aryl triazine ring structure is mixed with a 37 wt% formaldehyde solution under a nitrogen or argon atmosphere at pH 8-11, at a concentration of 80-100... o Stir the reaction mixture for 8-12 hours. The reaction product settles in deionized water. Adjust the pH to 5, filter the mixture, and maintain the filter cake at 120-200 ml. o Phenolic resin was obtained by curing at C for 2-6 h, which served as a precursor for porous carbon materials. S12. Place the prepared phenolic resin into a tube furnace, and purge with nitrogen or argon gas at a flow rate of 20-50 ml / min, at a rate of 5-10 ml / min. o Heat at a rate of 500-800 °C / min o Carbonization at C for 1-3 hours yields phenolic resin-based carbon material. Then, carbon dioxide at a flow rate of 20-50 ml / min is introduced into a tube furnace, and the phenolic resin-based carbon material is heated at 5-10... o Heat at a rate of 800-1200 °C / min. o Phenolic resin-based porous carbon materials were prepared by activating the material at a temperature of 0.5-1.5 h. These materials were then used as cathode materials for rechargeable lithium thionyl chloride batteries.

2. A rechargeable lithium thionyl chloride battery, characterized in that, The rechargeable lithium thionyl chloride battery positive electrode material is prepared by the preparation method described in claim 1. The rechargeable lithium thionyl chloride battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode includes a current collector and a positive electrode material attached to the current collector. The electrolyte is a thionyl chloride solution containing chloride and fluoride.

3. The rechargeable lithium thionyl chloride battery according to claim 2, characterized in that, The current collector is made of nickel foam, carbon cloth, or stainless steel mesh. The chlorides in the electrolyte include aluminum chloride and / or lithium chloride; The fluoride in the electrolyte comprises lithium bis(fluorosulfonyl)imide and / or lithium bis(trifluoromethanesulfonyl)imide; The concentration of chloride in the electrolyte is 1-3 mol / L; The electrolyte contains fluoride at a mass of 2-4 wt% of the total mass of thionyl chloride and chloride. The negative electrode is metallic lithium; The diaphragm is a glass fiber diaphragm or a polymer diaphragm.

4. A method for preparing a rechargeable lithium thionyl chloride battery as described in claim 2 or 3, characterized in that, The specific steps are as follows: Preparation of the positive electrode: A dispersion of the positive electrode material for a rechargeable lithium thionyl chloride battery is added to a current collector and dried to obtain the positive electrode; Preparation of electrolyte: Chloride is added to thionyl chloride, and then fluoride is added to obtain electrolyte; Provides a negative electrode and a separator, and assembles the positive electrode, negative electrode, separator and electrolyte to obtain a rechargeable lithium thionyl chloride battery.

5. The preparation method according to claim 4, characterized in that, The preparation of the positive electrode includes the following steps: S21. A dispersion of rechargeable lithium thionyl chloride battery positive electrode material, conductive agent and binder is obtained by ultrasonication in anhydrous ethanol at a certain mass ratio. S22. Provide a current collector, add the dispersed liquid droplets onto the current collector and dry them to prepare a positive electrode.

6. The preparation method according to claim 5, characterized in that, In S21, the conductive agent is Ketjen black, acetylene black or conductive carbon black, and the binder is 60 wt% polytetrafluoroethylene concentrated dispersion. The mass ratio of positive electrode material: conductive agent: binder is 6-8:3-1:

1.

7. The preparation method according to claim 5, characterized in that, The preparation of the electrolyte includes the following steps: S31. Add aluminum chloride to thionyl chloride at a concentration of 1-3 mol / L and stir for 10-60 min. Then add lithium chloride to the solution at a concentration slightly higher than that of aluminum chloride and stir for 10-60 min, or do not add lithium chloride. After this step, the first solution is formed. S32. Add fluoride to the first solution. The amount of fluoride added is 2-4 wt% of the total mass of thionyl chloride and chloride. Stir for 0.5-8 h, then let stand for 8-24 h and take the supernatant to obtain the electrolyte.

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