Lithium battery carbon electrode modification method
By forming a polyMTAC film on the surface of the carbon electrode in a lithium battery, the problem of slow electrolyte wetting speed is solved, the activation rate of the lithium battery is improved, and the service life of the electrode is extended.
Patent Information
- Application Number
- CN202511105455.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-07
- Publication Date
- 2025-11-14
AI Technical Summary
The electrolyte in existing lithium-thionyl chloride system storage lithium batteries wets the electrodes slowly, which limits the improvement of activation rate.
A polyMTAC film was formed on the surface of a carbon electrode using a surface-initiated atom transfer radical polymerization method. This method increases the adhesion sites of hydrophilic groups through physical adsorption and chemical reaction, thereby improving the hydrophilicity and wetting speed of the electrode.
It significantly improves the hydrophilicity and wetting rate of the electrode, enhances the activation rate of the reserve lithium battery, and extends the lifespan of the electrode.
Smart Images
Figure CN120955076A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrode material preparation technology, and in particular to a method for modifying carbon electrodes for lithium batteries. Background Technology
[0002] Lithium-ion batteries are a new type of storage battery that has been developed in recent years. Due to their high energy density, stable discharge voltage, long operating time, and environmentally friendly and pollution-free battery system, they have become a leader in the current battery field. Among various storage lithium batteries, the lithium-thionyl chloride system storage lithium battery has been the most researched and widely used. The positive electrode material of the lithium-thionyl chloride system storage lithium battery is thionyl chloride liquid electrolyte, the negative electrode material is lithium, and activated carbon is used as the cathode material. The speed of the activation process of a storage lithium battery, i.e., the activation rate, is an important performance indicator. With the diversification of application scenarios, the requirements for the activation rate of storage lithium batteries are becoming increasingly stringent. The activation process of a storage lithium battery includes two sub-processes: the activation mechanism breaking the electrolyte and the electrolyte wetting the electrodes. The activation rate of a storage lithium battery is mainly determined by the speed of the activation mechanism breaking the electrolyte and the speed of the electrolyte wetting the electrodes. Therefore, accelerating the electrolyte wetting process should effectively improve the activation rate of the storage lithium battery.
[0003] However, there are no publicly available reports on how to accelerate the electrolyte wetting process of the electrodes to improve the activation rate of storage lithium batteries.
[0004] Refrigeration lithium batteries use activated carbon electrodes as the cathode material. Experiments show that unmodified activated carbon electrodes have poor hydrophilicity, with the smallest water contact angle, characterizing their hydrophilicity, reaching only 136°. This poor hydrophilicity reduces the rate of electrolyte wetting of the electrode, thus limiting the improvement of the activation rate of refrigeration lithium batteries. Summary of the Invention
[0005] The purpose of this invention is to provide a method for modifying carbon electrodes for lithium batteries, which results in electrodes with good hydrophilicity and fast wetting speed.
[0006] The technical solution to achieve the purpose of this invention is as follows:
[0007] A method for modifying a carbon electrode for a lithium battery includes the following steps:
[0008] S10, hydroxylation of carbon electrode surface: The carbon electrode substrate is washed with deionized water and ethanol and dried with pure nitrogen at 80°C; it is then cleaned with concentrated nitric acid for at least two hours, rinsed with distilled water and ethanol for 2-3 minutes each, and dried with pure nitrogen at 80°C to obtain a surface-hydroxylated carbon electrode.
[0009] S20, silanization of carbon electrode: The surface hydroxylated carbon electrode is immersed in a 0.5% triethoxysilane ethanol solution for 30 min, rinsed with anhydrous ethanol for 2-3 min, and dried with pure nitrogen at 80°C to obtain a silanized carbon electrode.
[0010] S30, carbon electrode with free radical initiator: The silanized carbon electrode is immersed in dichloromethane solution for 30 min, washed with ethanol and deionized water for 2-3 min respectively, and dried with pure nitrogen at 80℃ to obtain carbon electrode with free radical initiator;
[0011] S40, film formation on carbon electrode surface: After the carbon electrode with free radical initiator is polymerized with the polymerization solution in a flat-bottomed sealed container purified by argon gas, it is cleaned, dried and the surface copper ions are removed to obtain the modified carbon electrode.
[0012] Preferably, in step S10, the hydroxylation step on the carbon electrode surface, the concentration of the concentrated nitric acid is 70% by mass.
[0013] Preferably, in step S10, the carbon electrode surface hydroxylation step, the carbon electrode substrate is an activated carbon electrode prepared by a dry method.
[0014] Preferably, in step S30, where the carbon electrode carries a free radical initiator, the dichloromethane solution contains 0.37 mol of 2-bromo-2-methylpropionyl bromide and 0.42 mol of triethylamine per 10 mL of dichloromethane solution.
[0015] The step of forming a film on the carbon electrode surface in S40 includes:
[0016] S41, Preparation of polymerization solution: Mix MTAC monomer with ethylenediamine and dissolve it in a methanol-water solution placed in a sealed container. Stir the mixture with a magnetic rod at a speed of 300 rpm. Inject pure argon gas into the mixture in the form of bubbles for 30 minutes to obtain the polymerization solution.
[0017] S42, Atom Transfer Radical Polymerization: The carbon electrode with the radical initiator is placed in a flat-bottomed sealed container, and the air inside the container is purified with argon. Cuprous bromide and 2,2′-bipyridine are added to the flat-bottomed container for catalysis, and then argon is continuously injected for 30 min. The polymerization solution is pumped into the flat-bottomed container through a connecting tube, the container is sealed, and stored at room temperature for 18 h. The carbon electrode is washed with deionized water and ethanol for 2-3 min each, and dried with pure nitrogen to obtain the radical polymerized carbon electrode.
[0018] S43, Removal of copper ions from the carbon electrode surface: The free radical polymerized carbon electrode is immersed in NaCl solution for at least 48 h, washed with ethanol and deionized water for 2-3 min, and dried with pure nitrogen at 80 °C to obtain the modified carbon electrode.
[0019] Preferably, in step S41, the volume ratio of water to methanol in the methanol-water solution is 2:1.
[0020] Preferably, in step S41, the polymerization solution preparation step, the MTAC monomer is methacryloyloxyethyltrimethylammonium chloride.
[0021] Preferably, in step S41, the concentration of the MTAC monomer is 1 mol / L and the concentration of ethylenediamine is 0.5 mol / L.
[0022] Preferably, in step S42, the atom transfer radical polymerization step, the concentration of cuprous bromide is 0.05 mol / L and the concentration of 2,2′-bipyridine is 0.1 mol / L.
[0023] Preferably, in step S43, the copper ion removal process on the carbon electrode surface, the concentration of the NaCl solution is 3 mol / L.
[0024] Compared with the prior art, the significant advantages of this invention are:
[0025] 1. Solved the problem of difficult polymerization of hydrophilic molecules on electrode surface: This invention is the first to apply the surface-initiated atom transfer radical polymerization method to the carbon electrode surface to form a polyMTAC film. Compared with the ordinary chemical grafting method, this method provides more polymerization sites for hydrophilic group molecules, allowing more hydrophilic group molecules to attach to the surface of the carbon electrode, which greatly improves the adhesion ability of hydrophilic molecules.
[0026] 2. Good electrode hydrophilicity and high wetting rate: This invention forms a polyMTAC film on the surface of a carbon electrode through surface-initiated atom transfer radical polymerization, which improves the electrode hydrophilicity and accelerates the wetting rate, thus improving the activation rate of the storage lithium battery.
[0027] 3. Extending electrode lifespan: The present invention forms a polyMTAC film on the surface of the carbon electrode, which can reduce the oxidation rate of the carbon electrode of the storage lithium battery during long-term storage, thereby extending the electrode lifespan.
[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0029] Figure 1 This is the main flowchart of the lithium battery carbon electrode modification method of the present invention.
[0030] Figure 2 yes Figure 1 A flowchart of the film formation process on the surface of a medium-carbon electrode.
[0031] Figure 3This is a chemical schematic diagram of the lithium battery carbon electrode modification method of the present invention. Detailed Implementation
[0032] Example 1:
[0033] The present invention provides a method for modifying the carbon electrode of a lithium battery, employing methods such as... Figure 1 The process shown is implemented as follows. Specifically, it includes the following steps:
[0034] S10, hydroxylation of carbon electrode surface: The carbon electrode substrate was washed with deionized water and ethanol, and dried with pure nitrogen at 80°C; it was then cleaned with 70% nitric acid for two hours, rinsed with distilled water and ethanol for 2 minutes each, and dried with pure nitrogen at 80°C to obtain a surface-hydroxylated carbon electrode.
[0035] In this embodiment, the carbon electrode substrate is an activated carbon electrode prepared by a dry method.
[0036] Activated carbon electrodes can be prepared by dry or wet methods.
[0037] Experimental exploration and theoretical analysis revealed that the evaporation of solvents in wet processes leaves gaps between the active material and the conductive agent, resulting in poor material contact. Immersion in various solvents during the modification process may cause electrode cracking. Using activated carbon electrodes prepared by dry methods makes it easier to obtain modified carbon electrodes with good performance and intact structure. Therefore, this invention preferably uses activated carbon electrodes prepared by dry methods as the carbon electrode substrate.
[0038] Rinsing with distilled water and ethanol for 2-3 minutes each can achieve the goal of cleaning the surface of the hydroxylated carbon electrode.
[0039] S20, silanization of carbon electrode: The surface hydroxylated carbon electrode is immersed in a 0.5% triethoxysilane ethanol solution for 30 min, then rinsed with anhydrous ethanol for 2 min, and dried with pure nitrogen at 80°C to obtain a silanized carbon electrode.
[0040] Rinsing the silanized carbon electrode with anhydrous ethanol for 2-3 minutes can achieve the purpose of cleaning.
[0041] S30, carbon electrode with free radical initiator: The silanized carbon electrode is immersed in dichloromethane solution for 30 min, washed with ethanol and deionized water for 2 min each, and dried with pure nitrogen at 80 °C to obtain a carbon electrode with free radical initiator.
[0042] The dichloromethane solution contains 0.37 mol of 2-bromo-2-methylpropionyl bromide and 0.42 mol of triethylamine per 10 mL of dichloromethane solution. Rinsing with ethanol and deionized water for 2-3 minutes each can achieve the goal of cleaning the carbon electrode surface containing the free radical initiator.
[0043] S40, Film formation on the carbon electrode surface: The carbon electrode with free radical initiator is polymerized with the polymerization solution in an argon-purified flat-bottomed vial. After cleaning, drying, and removal of surface copper ions, a modified carbon electrode is obtained.
[0044] like Figure 2 As shown, step S40, the carbon electrode surface film formation step, includes:
[0045] S41, Preparation of polymerization solution:
[0046] MTAC monomer and ethylenediamine were mixed and dissolved in a methanol-water solution placed in a sealed container. The mixture was stirred with a magnetic rod at 300 rpm. Pure argon gas was injected into the mixture in the form of bubbles for 30 minutes to obtain a polymerization solution.
[0047] The MTAC monomer refers to methacryloyloxyethyltrimethylammonium chloride.
[0048] Compared to other organic polymers, MTAC molecules have good thermal and chemical stability, and can maintain their performance in a variety of environments.
[0049] The concentration of MTAC monomer is 1 mol / L, and the concentration of ethylenediamine is 0.5 mol / L.
[0050] Ethylenediamine is chosen as the reagent for introducing amino groups, mainly due to its advantages such as its diamino structure, high reactivity, low steric hindrance, low cost, and multifunctionality.
[0051] The volume ratio of water to methanol in the methanol-water solution is 2:1.
[0052] S42, atom transfer radical polymerization:
[0053] The carbon electrode with the free radical initiator was placed in a flat-bottomed, sealed container, and the air inside the container was purified with argon. Cuprous bromide and 2,2′-bipyridine were added to the flat-bottomed container for catalysis, and then argon was continuously injected for 30 min. The polymerization solution was pumped into the flat-bottomed container through a connecting tube, the container was sealed, and stored at room temperature for 18 h. The carbon electrode was washed with deionized water and ethanol for 2-3 min each, and dried with pure nitrogen to obtain the free radical polymerized carbon electrode.
[0054] The concentration of cuprous bromide is 0.05 mol / L, and the concentration of 2,2′-bipyridine is 0.1 mol / L.
[0055] S43, Removal of copper ions from carbon electrode surface:
[0056] The free radical polymerized carbon electrode was immersed in NaCl solution for at least 48 h, washed with ethanol and deionized water for 2 min, and dried with pure nitrogen at 80 °C to obtain the modified carbon electrode.
[0057] The concentration of the NaCl solution is 3 mol / L.
[0058] A 3 mol / L NaCl solution can better remove copper ions from the electrode surface.
[0059] The chemical principle of the lithium battery carbon electrode modification method of this invention is as follows: Figure 3 As shown.
[0060] from Figure 3 It can be seen that hydroxyl molecules are formed on the surface of the activated carbon electrode under the action of concentrated nitric acid; the hydroxylated activated carbon electrode combines with siloxane molecules in the reagent of triethoxysilane and ethanol to complete silanization; the silanized activated carbon electrode forms an activated carbon electrode with free radical initiator in a dichloromethane solution containing 2-bromo-2-methylpropionyl bromide and triethylamine; finally, the activated carbon electrode is polymerized with MTAC monomer and ethylenediamine in a water-methanol solution under the catalysis of cuprous bromide and bipyridine, and finally a polyMTAC film with a large number of amino molecules is formed on the surface.
[0061] from Figure 3 As can be seen, this invention prepares a polyMTAC film on the surface of a carbon electrode using surface-initiated atom transfer radical polymerization (ATRP). The carbon electrode surface is hydroxylated using concentrated nitric acid, and then immersed in an APTES ethanol solution. The carbon electrode is silanized through physical adsorption and chemical reaction. An initiator is then coupled to the electrode surface via a silane coupling agent. Finally, MTAC molecules and ethylenediamine are polymerized on the electrode surface using the initiator. This process results in a large number of hydrophilic functional groups polymerized on the activated carbon electrode surface, improving the electrode's interfacial properties, increasing its hydrophilicity, and accelerating the wetting rate. By accelerating the electrolyte wetting process of the electrode, the activation rate of the storage lithium battery can be effectively improved.
[0062] The modified carbon electrode prepared by this invention reduces the water contact angle from 136° to 118°, resulting in a significant improvement in wettability. This improvement in wettability has a positive impact on the activation rate of the battery, and the discharge performance and mechanical properties of the electrode do not change significantly, allowing it to continue to be used normally.
[0063] This invention employs atom transfer radical polymerization modification technology, which is relatively mature and allows for controllable modification results. It also utilizes a dry-process carbon electrode with better compaction density, and the preparation process is non-toxic and harmless. Because this method improves the electrode surface contact angle by preparing a polyMTAC molecular film on the carbon electrode surface and binding amino molecules, it is applicable not only to the binding of amino molecules but also to the modification of hydrophilic molecules such as hydroxyl and carboxyl groups on the carbon electrode surface.
[0064] 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 method for modifying a carbon electrode for a lithium battery, characterized in that, Includes the following steps: S10, hydroxylation of carbon electrode surface: The carbon electrode substrate is washed with deionized water and ethanol and dried with pure nitrogen at 80°C; it is then cleaned with concentrated nitric acid for at least two hours, rinsed with distilled water and ethanol for 2-3 minutes each, and dried with pure nitrogen at 80°C to obtain a surface-hydroxylated carbon electrode. S20, silanization of carbon electrode: The surface hydroxylated carbon electrode is immersed in a 0.5% triethoxysilane ethanol solution for 30 min, rinsed with anhydrous ethanol for 2-3 min, and dried with pure nitrogen at 80°C to obtain a silanized carbon electrode. S30, carbon electrode with free radical initiator: The silanized carbon electrode is immersed in dichloromethane solution for 30 min, washed with ethanol and deionized water for 2-3 min respectively, and dried with pure nitrogen at 80℃ to obtain carbon electrode with free radical initiator; S40, film formation on carbon electrode surface: After the carbon electrode with free radical initiator is polymerized with the polymerization solution in a flat-bottomed sealed container purified by argon gas, it is cleaned, dried and the surface copper ions are removed to obtain the modified carbon electrode.
2. The method for modifying the carbon electrode of a lithium battery according to claim 1, characterized in that: In step S10, the hydroxylation step on the carbon electrode surface, the concentration of concentrated nitric acid is 70% by mass.
3. The method for modifying the carbon electrode of a lithium battery according to claim 1, characterized in that: In step S10, the carbon electrode surface hydroxylation step, the carbon electrode substrate is an activated carbon electrode prepared by a dry method.
4. The method for modifying the carbon electrode of a lithium battery according to claim 1, characterized in that: In step S30, where the carbon electrode carries a free radical initiator, the dichloromethane solution contains 0.37 mol of 2-bromo-2-methylpropionyl bromide and 0.42 mol of triethylamine per 10 mL of dichloromethane solution.
5. The method for modifying a lithium battery carbon electrode according to any one of claims 1 to 4, characterized in that, The step of forming a film on the carbon electrode surface in S40 includes: S41, Preparation of polymerization solution: Mix MTAC monomer with ethylenediamine and dissolve it in a methanol-water solution placed in a sealed container. Stir the mixture with a magnetic rod at a speed of 300 rpm. Inject pure argon gas into the mixture in the form of bubbles for 30 minutes to obtain the polymerization solution. S42, Atom Transfer Radical Polymerization: The carbon electrode with the radical initiator is placed in a flat-bottomed sealed container, and the air inside the container is purified with argon. Cuprous bromide and 2,2′-bipyridine are added to the flat-bottomed container for catalysis, and then argon is continuously injected for 30 min. The polymerization solution is pumped into the flat-bottomed container through a connecting tube, the container is sealed, and stored at room temperature for 18 h. The carbon electrode is washed with deionized water and ethanol for 2-3 min each, and dried with pure nitrogen to obtain the radical polymerized carbon electrode. S43, Removal of copper ions from the carbon electrode surface: The free radical polymerized carbon electrode is immersed in NaCl solution for at least 48 h, washed with ethanol and deionized water for 2-3 min, and dried with pure nitrogen at 80 °C to obtain the modified carbon electrode.
6. The method for modifying the carbon electrode of a lithium battery according to claim 5, characterized in that: In step S41, the volume ratio of water to methanol in the methanol-water solution is 2:
1.
7. The method for modifying the carbon electrode of a lithium battery according to claim 5, characterized in that: In step S41, the polymerization solution preparation step, the MTAC monomer is methacryloyloxyethyltrimethylammonium chloride.
8. The method for modifying the carbon electrode of a lithium battery according to claim 5, characterized in that: In step S41, the concentration of the MTAC monomer is 1 mol / L and the concentration of ethylenediamine is 0.5 mol / L.
9. The method for modifying the carbon electrode of a lithium battery according to claim 5, characterized in that: In step S42, the atom transfer radical polymerization, the concentration of cuprous bromide is 0.05 mol / L and the concentration of 2,2′-bipyridine is 0.1 mol / L.
10. The method for modifying the carbon electrode of a lithium battery according to claim 5, characterized in that: In step S43, the copper ion removal process on the carbon electrode surface, the concentration of the NaCl solution is 3 mol / L.