CN-121709548-B - Silicon-oxygen negative electrode prelithiation method based on lithium-ion solution and application thereof

CN121709548BCN 121709548 BCN121709548 BCN 121709548BCN-121709548-B

Abstract

The invention discloses a silicon-oxygen negative electrode prelithiation method based on a lithium-ion solution and application thereof, and belongs to the technical field of lithium ion batteries. Dissolving lithium metallocene in an organic solvent under inert atmosphere to prepare a pre-lithiation solution, immersing a silicon-oxygen negative electrode plate in the pre-lithiation solution to realize pre-lithiation through chemical displacement reaction, and then taking out the electrode plate for cleaning and drying. According to the invention, by utilizing moderate reduction potential of the lithium-ion battery, uniform and controllable bulk pre-lithiation can be carried out on the silicon-oxygen negative electrode, so that irreversible lithium loss in the first charge and discharge process is effectively compensated, and the first coulomb efficiency is improved from 75-85% to more than 90%. The method has the advantages of simple process, safety, reliability, low cost, high compatibility with the existing battery manufacturing process, suitability for large-scale production and great value for promoting the commercial application of the high-energy-density silicon-oxygen negative electrode.

Inventors

SHEN YONGMIAO
ZHAO FUGANG
ZHANG KAI
SHEN YAFEN
XI ZIWEI
QI HANG
YIN YUYUN
Wang Shanshun

Assignees

浙江理工大学嵊州创新研究院有限公司
绍兴市锐依博新材料技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260211

Claims (10)

1. A method for pre-lithiation of a silicon-oxygen negative electrode based on a lithium-ion solution is characterized by comprising the following steps: s1, dissolving lithium metallocene in an organic solvent in an inert atmosphere to form a prelithiation solution with the concentration of 0.05-0.5 mol/L; S2, contacting the silicon-oxygen negative electrode plate with a pre-lithiation solution and completing a pre-lithiation reaction; S3, taking out the silicon-oxygen negative electrode piece subjected to the pre-lithiation reaction, cleaning and drying to obtain a pre-lithiated silicon-oxygen negative electrode; Cyclopentadienyl anions dissociated from the lithium cyclopentadienyl in the organic solvent are taken as electron acceptors to perform spontaneous oxidation-reduction reaction with the silicon-oxygen anode material.
2. The method of claim 1, wherein the concentration of the pre-lithiation solution is 0.05 to 0.1 mol/L.
3. The method according to claim 1, wherein the organic solvent is at least one of an ether solvent and a carbonate solvent.
4. The method of claim 3, wherein the ether solvent is at least one of ethylene glycol dimethyl ether, tetrahydrofuran, and dimethoxyethane, and the carbonate solvent is at least one of dimethyl carbonate, diethyl carbonate, and ethylene carbonate.
5. The method of claim 3, wherein the organic solvent is a mixed solvent of an ether solvent and a carbonate solvent, and the volume ratio of the mixed solvent is 8:2-5:5.
6. The method of claim 1, wherein the pre-lithiation reaction is performed at a temperature of 10-40 ℃ for a period of 10 s-30 min.
7. The method of claim 6, wherein the pre-lithiation reaction time is 1-10 minutes.
8. The method according to claim 1, wherein the washing is performed with dimethoxyethane or dimethyl carbonate.
9. The method of claim 1, wherein the silicon-oxygen negative electrode plate further comprises a binder, and the binder is polyacrylic acid or sodium alginate.
10. Use of the pre-lithiated silicon oxide negative electrode made by the method of claim 1 in a lithium ion battery.

Description

Silicon-oxygen negative electrode prelithiation method based on lithium-ion solution and application thereof Technical Field The invention relates to a silicon-oxygen negative electrode prelithiation method based on a lithium-ion solution and application thereof, and belongs to the technical field of lithium ion batteries. Background Silicon-based anodes play a key role in commercial Lithium Ion Batteries (LIB) to maximize the range of Electric Vehicles (EV) and reduce range anxiety, with silicon (4200 mAhg -1) having a significantly higher specific capacity than the specific capacity of conventional graphite anodes 372mAhg -1. However, silicon can exhibit a volume expansion of about 400% in applications, such large volume expansion severely hampers its commercialization process, leading to pulverization of the active material, loss of electrical contact, and continued growth of Solid Electrolyte Interface (SEI) during charge and discharge. SiO x (0≤x≤2) materials exhibit compromised performance, with a better tradeoff between theoretical capacity (about 2400mAhg -1) and volume change (about 200%). However, commercial applications of silicon-oxygen cathodes face a serious challenge of extremely low first coulombic efficiency. In the first lithiation process, the silicon-oxygen negative electrode can generate irreversible side reaction with electrolyte to form a solid electrolyte interface film (SEI film), and meanwhile, electrochemical inert Li 2 O and lithium silicate can be generated in the material. These processes irreversibly consume large amounts of lithium ions from the positive electrode, resulting in a first coulombic efficiency of the silicon-oxygen negative electrode of typically only 45-75%. This not only directly reduces the reversible capacity of the battery, but also severely limits the increase in the energy density of the full battery. To compensate for this initial lithium loss, a prelithiation technique becomes an indispensable key element. The existing pre-lithiation technology generally directly coats slurry containing lithium powder on the surface of an electrode, but the lithium powder in the method has extremely high chemical activity, extremely severe requirements on humidity and oxygen control of a production environment, combustion explosion risks, difficulty in controlling the distribution uniformity of the lithium powder and high cost, and the negative electrode is pre-charged through an external circuit. Meanwhile, the method requires a complex fixture and additional working procedures, has low production efficiency, is difficult to be compatible with the existing roll-to-roll production line, has high industrialization cost, and is widely researched to supplement lithium by adopting strong reducing reagents such as biphenyl lithium, naphthalene lithium and the like. Although the lithium supplementing effect is remarkable, the reduction potential of the reagents is too low (can be lower than 1.0V relative to Li/Li +), the properties are too active, and the reagents are easy to swell and decompose commonly used binders (such as CMC and SBR) in the electrode, so that the structural integrity of the electrode is damaged. Meanwhile, the reagents are poor in stability and are unfavorable for storage and transportation. Therefore, there is an urgent need in the art to develop a pre-lithiation method that is not only efficient in lithium supplementation, but also safe, process compatible, and friendly to the electrode structure. Disclosure of Invention In view of the above, the invention provides a method for pre-lithiation of a silicon oxygen negative electrode based on a lithium-containing solution, which solves the technical problems of low initial coulombic efficiency of a silicon oxide material, poor pre-lithiation effect caused by complex process, unsafe lithium source (such as metal lithium powder) or insufficient reactivity of the lithium source (such as lithium carbonate) in the traditional pre-lithiation method, and has the advantages of simple process, safety, high efficiency, easy mass production and the like. In order to achieve the above purpose, the present invention adopts the following technical scheme: A method for pre-lithiation of a silicon-oxygen negative electrode based on a lithium-ion solution comprises the following steps: Dissolving the lithium metallocene powder in an organic solvent in a glove box or a reaction kettle which is protected by inert gas (such as argon), and stirring until the lithium metallocene powder is completely dissolved to form a prelithiation solution with the concentration of 0.01 mol/L to 0.5 mol/L. And step two, immersing the dry silicon-oxygen negative electrode plate into the pre-lithiation solution prepared in the step one, and carrying out soaking reaction for 10 seconds to 30 minutes in a normal-temperature environment of 10 ℃ to 40 ℃. And thirdly, after the reaction is finished, taking the silica negative electrode plate out of