Silicon-oxygen negative electrode prelithiation method based on lithium metallocene solution and application
By using lithium-magnesium solution to pre-lithiate the silicon-oxygen anode, the problem of low initial coulombic efficiency of silicon-oxygen anode in the existing technology is solved, achieving a pre-lithiation effect that is efficient, safe, and easy to scale up, thereby improving the energy density and production efficiency of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV OF TECH SHENGZHOU INNOVATION RES INST CO LTD
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing pre-lithiation technology suffers from problems such as complex processes, safety concerns, high costs, incompatibility with existing roll-to-roll production lines, and low initial coulombic efficiency of silicon-oxygen anodes due to insufficient lithium source activity.
Lithium-based solutions were used to pre-lithiate silicon-oxygen anodes. Lithium-based powder was dissolved in an organic solvent under inert gas protection to form a pre-lithiation solution with a concentration of 0.01 mol/L to 0.5 mol/L. After soaking the silicon-oxygen anode sheet, it was cleaned and dried. Uniform and controllable bulk pre-lithiation was achieved by utilizing the moderate reduction potential of lithium-based powder.
It significantly improves the initial coulombic efficiency of silicon-oxygen anodes to over 90%, reduces safety risks, increases production efficiency and battery energy density, and possesses high safety and high process compatibility.
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Figure CN121709548B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution and its application, belonging to the field of lithium-ion battery technology. Background Technology
[0002] To maximize the driving range of electric vehicles (EVs) and reduce range anxiety, silicon-based anodes play a crucial role in commercially available lithium-ion batteries (LIBs), compared to traditional graphite anodes (372 mAh g). -1 Compared to the specific capacity, silicon (4200mAh g) -1 Silicon possesses a significantly high specific capacity. However, silicon exhibits a volume expansion of approximately 400% in applications. This substantial volume expansion severely hinders its commercialization, leading to active material pulverization, electrical contact loss, and continuous growth of the solid electrolyte interface (SEI) during charge and discharge. x (0≤x≤2) The material exhibits a compromise in performance, with a theoretical capacity (approximately 2400 mAh g). -1 A better trade-off has been achieved between the positive and negative energy density (approximately 200%). However, the commercial application of silicon-oxygen anodes faces a severe challenge: extremely low initial coulombic efficiency. During the initial lithiation process, the silicon-oxygen anode undergoes irreversible side reactions with the electrolyte, forming a solid electrolyte interphase (SEI) film. Simultaneously, electrochemically inert Li₂O and lithium silicates are generated within the material. These processes irreversibly consume a large amount of lithium ions from the positive electrode, resulting in an initial coulombic efficiency of only 45–75% for silicon-oxygen anodes. This not only directly reduces the reversible capacity of the battery but also severely limits the improvement of the overall battery energy density.
[0003] To compensate for this initial lithium loss, pre-lithiation technology becomes an indispensable key step. Existing pre-lithiation technologies generally involve directly coating a lithium powder-containing slurry onto the electrode surface. However, this method uses highly chemically reactive lithium powder, requiring extremely stringent control of humidity and oxygen levels in the production environment, posing a risk of combustion and explosion. Furthermore, controlling the uniformity of lithium powder distribution is difficult, and the cost is high. Alternatively, the negative electrode can be pre-charged via an external circuit. This method also requires complex fixtures and additional processes, resulting in low production efficiency, incompatibility with existing roll-to-roll production lines, and high industrialization costs. Current research often uses strong reducing agents such as lithium biphenyl and lithium naphthylene for lithium replenishment. While these agents show significant lithium replenishment effects, their reduction potentials are too low (relative to Li / Li). + These reagents (which can operate below 1.0V) are too reactive and can easily cause swelling and decomposition of commonly used binders in electrodes (such as CMC and SBR), damaging the integrity of the electrode structure. Furthermore, these reagents themselves have poor stability, making them unsuitable for storage and transportation.
[0004] Therefore, there is an urgent need in this field to develop a pre-lithiation method that is efficient in lithium replenishment, has high safety and high process compatibility, and is friendly to electrode structure. Summary of the Invention
[0005] In view of this, the present invention provides a silicon-oxygen anode pre-lithiation method based on lithium-magnesium solution to solve the technical problems of low initial coulombic efficiency of silicon suboxide materials in the prior art, as well as the poor pre-lithiation effect caused by complex processes, unsafe lithium sources (such as lithium metal powder) or insufficient reactivity of lithium sources (such as lithium carbonate) in traditional pre-lithiation methods. It has the advantages of simple process, safety and efficiency, and easy large-scale production.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution includes the following steps:
[0008] Step 1: In a glove box or reactor protected by an inert gas (such as argon), dissolve the lithium-magnesium powder in an organic solvent and stir until completely dissolved to form a pre-lithiation solution with a concentration of 0.01 mol / L to 0.5 mol / L.
[0009] Step 2: Immerse the dried silicon-oxygen negative electrode sheet in the pre-lithiation solution prepared in Step 1, and immerse it at room temperature (10°C to 40°C) for 10 seconds to 30 minutes.
[0010] Step 3: After the reaction is complete, remove the silicon-oxygen anode sheet from the solution and immediately perform a rapid and thorough cleaning with a volatile cleaning solvent to remove residual pre-lithiation reagents and byproducts from the electrode surface and pores. Subsequently, place the electrode sheet in a vacuum environment at 60°C to 120°C for 2 to 12 hours to dry, finally obtaining the pre-lithiation completed silicon-oxygen anode sheet.
[0011] The above scheme uses lithium magnesia as a pre-lithiation reagent. By utilizing the moderate reduction potential of lithium magnesia, it can perform uniform and controllable bulk pre-lithiation of silicon-oxygen anode, effectively compensating for irreversible lithium loss during the first charge and discharge process, and increasing the first coulombic efficiency from 75-85% to over 90%.
[0012] Furthermore, as a preferred option:
[0013] In step one,
[0014] The concentration of the pre-lithiation solution ranges from 0.02 mol / L to 0.1 mol / L to achieve optimal reaction kinetics and uniformity.
[0015] The organic solvent is an ether solvent (such as ethylene glycol dimethyl ether, tetrahydrofuran, dimethoxyethane) and / or a carbonate solvent (such as dimethyl carbonate, ethylene carbonate). More preferably, a mixed solvent of ether and carbonate is used, with a volume ratio between 8:2 and 5:5. This ratio can balance the solubility of lithium magnesia and the wettability of the electrode.
[0016] In step two,
[0017] The pre-lithiation reaction time is 1 to 10 minutes to ensure sufficient reaction while avoiding excessively long process cycles.
[0018] In step three,
[0019] The cleaning solvent is dimethoxyethane or dimethyl carbonate, which has good solubility and volatility, and is easy to dry quickly.
[0020] To improve the compatibility of the pre-lithiation process, the binder contained in the silicon-oxygen anode sheet is a water-based binder with good stability to the reducing environment, such as polyacrylic acid or sodium alginate.
[0021] Compared with the prior art, the technical solution provided by the present invention has the following significant advantages:
[0022] 1) Lithium-cadmium has a moderate reduction potential (approximately 0.6 ~ 0.7 V vs. Li / Li). + This technology can efficiently supply lithium to the silicon-oxygen anode while ensuring a mild and uniform reaction, achieving bulk pre-lithiation from the electrode surface to the interior, and steadily improving the first coulombic efficiency to over 90%.
[0023] 2) The lithium source chosen is lithium magnesia solution, which has stable chemical properties and is far superior to reactive lithium powder and easily decomposed lithium biphenyl / naphthalene, greatly reducing safety risks during storage, transportation and production.
[0024] 3) This method is a solution-based method, which can be directly inserted after the electrode is manufactured without modifying the existing production line. Its compatibility with binders such as polyacrylic acid ensures the integrity of the electrode structure after pre-lithiation.
[0025] 4) By simply adjusting the solution concentration and reaction time, the amount of lithium replenishment can be precisely controlled, avoiding lithium plating problems caused by insufficient lithium replenishment or excessive pre-lithiation, resulting in good product consistency.
[0026] 5) The raw materials are readily available and the process is simple. It can significantly improve the energy density of batteries and has extremely high commercial value and market competitiveness. Attached Figure Description
[0027] Figure 1 This is a schematic diagram illustrating the working principle of pre-lithiation in this application.
[0028] Figure 2 To illustrate the effect of pre-lithiation on the microstructure of the product, part a) in the figure is the SEM image of the product of Example 1, and part b) is the SEM image of the product of Comparative Example 1.
[0029] Figure 3 To illustrate the effect of pre-lithiation on the electrochemical performance of the product, part a) in the figure is the first cycle graph of the specific capacitance-voltage of the product of Example 1 at a current density of 100 mA / g, and part b) is the first cycle graph of the specific capacitance-voltage of the product of Comparative Example 1 at a current density of 100 mA / g. Detailed Implementation
[0030] The present invention will be further described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.
[0031] Example 1
[0032] This embodiment presents a method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution, the process of which is as follows:
[0033] Step 1: In an argon-atmosphere glove box (H2O, O2 < 0.1 ppm), accurately weigh 0.184 g of lithium monoxide powder, dissolve it in 20 mL of ethylene glycol dimethyl ether, and stir magnetically for 30 minutes to prepare a 0.05 mol / L pre-lithiation solution.
[0034] Step 2: Take a circular silicon-oxygen negative electrode sheet with a diameter of 15mm, immerse it completely in the above pre-lithiation solution, and let it stand at 25°C for 5 minutes to react.
[0035] Step 3: After the reaction is complete, remove the electrode with tweezers and quickly immerse it in a beaker containing 20 mL of dimethyl carbonate. Clean it with sonication for 30 seconds. Repeat this cleaning step twice.
[0036] Step four: Transfer the cleaned electrode to a vacuum oven and dry it at 80°C for 6 hours to obtain a pre-lithiated silicon-oxygen anode.
[0037] Example 2
[0038] This embodiment presents a method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution, the process of which is as follows:
[0039] Step 1: In an argon-atmospheric glove box, accurately weigh 0.073 g of lithium monoxide powder and dissolve it in 20 mL of ethylene glycol dimethyl ether to prepare a 0.02 mol / L pre-lithiation solution.
[0040] Step 2: Take a circular silicon-oxygen negative electrode sheet with a diameter of 15mm, immerse it completely in the above pre-lithiation solution, and let it stand at 25°C for 1 minute to react.
[0041] Step 3: After the reaction is complete, remove the electrode, clean it with dimethyl carbonate solvent and dry it to obtain a pre-lithiated silicon-oxygen anode.
[0042] Example 3
[0043] This embodiment presents a method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution, the process of which is as follows:
[0044] Step 1: In an argon-atmospheric glove box, accurately weigh 0.368 g of lithium monoxide powder and dissolve it in a mixed solvent (volume ratio 8:2) consisting of 16 mL of ethylene glycol dimethyl ether and 4 mL of dimethyl carbonate to prepare a 0.1 mol / L pre-lithiation solution.
[0045] Step two, take a piece with a higher capacity (approximately 3.5 mAh / cm²). 2 The silicon-oxygen negative electrode sheet was completely immersed in the above pre-lithiation solution and allowed to stand at 25°C for 10 minutes.
[0046] Step 3: After the reaction is complete, remove the electrode, clean it with dimethyl carbonate solvent and dry it to obtain a pre-lithiated silicon-oxygen anode.
[0047] Comparative Example 1
[0048] The same circular silicon-oxygen anode sheet as in Example 1 was used, but without any pre-lithiation treatment.
[0049] Comparative Example 2
[0050] The setup for this comparative example is the same as that for Example 1, except that the lithium magnesia powder is replaced with an equimolar amount of lithium naphthalene.
[0051] The products obtained from the above embodiments and comparative examples were used as negative electrode materials in button-type lithium-ion batteries, and the assembly process is as follows:
[0052] Using the electrodes corresponding to Examples 1-3, Comparative Examples 1 and 2 as working electrodes, lithium metal sheets as counter / reference electrodes, glass fiber membranes as separators, 1 mmol / L LiPF6 as electrolyte, ethylene carbonate / diethyl carbonate / ethyl methyl carbonate (volume ratio 1:1:1) as solvent, and 10% fluoroethylene carbonate as electrolyte additive, CR2032 coin cells were assembled in a glove box. Charge-discharge tests were performed on the Xinwei Battery Testing System, with a voltage window of 0.01V-1.5V and a current density of 0.1C. The test results are shown in the table below.
[0053] Table 1: Charge-discharge cycle test results of negative electrode materials for different schemes
[0054] .
[0055] As can be seen from Table 1, the initial coulombic efficiency of the silicon-oxygen anode in Comparative Example 1 (without pre-lithiation treatment) is only 59.4%.
[0056] Combination Figure 1 The schematic diagram illustrating the performance improvement of lithium-ion batteries through pre-lithiation shows that, during the first charge-discharge cycle, unlithiated electrodes undergo violent side reactions with the electrolyte, generating electrochemically inert components such as lithium oxide and lithium silicate salts. These byproducts not only cannot participate in subsequent reversible cycling but also irreversibly consume a large amount of active lithium, leading to a significant decrease in initial coulombic efficiency and severe irreversible capacity loss. In contrast, pre-lithiated electrodes have a stable solid-state electrolyte interface film pre-constructed on their surface, effectively inhibiting direct contact between the active material and the electrolyte, reducing side reactions, and thus significantly improving initial charge-discharge efficiency and reducing irreversible capacity loss. This lays an important foundation for improving the overall cycle stability and energy density of the battery.
[0057] Combination Figure 2 As can be seen, the surface of Example 1 is significantly densified, with pores filled and edges rounded, while the surface of Comparative Example 1 material is porous and angular. This indicates that active lithium has been embedded within the material during pre-lithiation and reacts with surface components to form a uniform lithium silicate coating layer. This dense layer effectively suppresses continuous electrolyte penetration and side reactions in subsequent cycles, providing a key structural basis for improving initial efficiency and cycle stability. Figure 3 The first charge-discharge cycle diagram at a current density of 100 mAh / g further confirms the significant improvement in electrochemical performance of the silicon-oxygen anode pre-lithiation material.
[0058] In comparison, the initial coulombic efficiency of Examples 1 to 3 was significantly improved, reaching 90.4%, 87.6%, and 91.3%, respectively. The pre-lithiation method provided in this application can introduce active lithium into the silicon-oxygen anode material in advance through chemical means, effectively compensating for irreversible lithium consumption in the first cycle, thereby significantly improving its initial coulombic efficiency.
[0059] Regarding preparation parameters: Example 1 (0.05 mol / L, reaction time 5 min) served as the baseline conditions and achieved excellent pre-lithiation results. Example 2 (0.02 mol / L, reaction time 1 min) achieved an initial coulombic efficiency of 87.6% even with lower reagent concentrations and shorter reaction times. This result demonstrates that the method of the present invention remains effective under relatively mild process conditions, possessing cost advantages and the potential for rapid processing, making it suitable for industrial scenarios with high production efficiency requirements. For high areal capacity electrodes, Example 3 (0.1 mol / L, mixed solvent, reaction time 10 min) achieved a maximum initial coulombic efficiency of 91.3% by increasing the reagent concentration, using a mixed solvent system, and extending the reaction time. This result indicates that the method of the present invention has good tunability and can be adapted to different electrode materials by optimizing process parameters, exhibiting broad applicability.
[0060] Comparative Example 2 used an equimolar amount of lithium naphthalene instead of lithium molar for pre-lithiation. Although its initial coulombic efficiency (89.1%) was significantly improved compared to Comparative Example 1, it still lagged behind Example 1 (90.4%) and Example 3 (91.3%). More importantly, the initial charge specific capacity of Comparative Example 2 (2031 mAh / g) was significantly lower than that of Example 1 (2279 mAh / g) and Example 3 (2261 mAh / g).
[0061] This phenomenon can be attributed to the differences in the reaction mechanisms of different pre-lithiation reagents: Naphthalene lithium has a low reduction potential and an overly vigorous reaction process, which may damage the electrode microstructure, causing some active materials to deactivate and thus reducing the reversible capacity. In contrast, the lithium magnesite used in this invention has a moderate reduction potential, enabling efficient pre-lithiation while better maintaining the structural integrity of the electrode and ensuring full capacity utilization.
[0062] The mechanism of the pre-lithiation method described in this invention lies in the fact that the cyclopentadienyl anion dissociated from lithium-magnetic compounds in an organic solvent acts as an electron acceptor, undergoing a spontaneous redox reaction with the silicon-oxygen anode material. The silicon-oxygen material loses electrons, while lithium ions insert into its crystal lattice, achieving pre-lithiation. This reaction process is mild and controllable, enabling uniform bulk pre-lithiation and is structurally friendly. Based on the test results and analysis of the above embodiments and comparative examples, it can be concluded that the pre-lithiation method based on lithium-magnetic solution provided by this invention can significantly improve the initial coulombic efficiency of silicon-oxygen anodes, has a wide process window, and allows for easy parameter adjustment. Furthermore, compared to strong reducing agents such as lithium naphthalene, it exhibits significant advantages in maintaining electrode capacity and structural integrity. This method provides an efficient, reliable, and industrially applicable solution to the technical challenge of low initial efficiency in silicon-oxygen anodes.
[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A method for pre-lithiation of silicon-oxygen anodes based on lithium-magnesium solution, characterized in that, The steps are as follows: S1, Under an inert atmosphere, lithium magnesia is dissolved in an organic solvent to form a pre-lithiation solution with a concentration of 0.05~0.5 mol / L; S2, the silicon-oxygen negative electrode sheet is brought into contact with the pre-lithiation solution and the pre-lithiation reaction is completed; S3, the silicon-oxygen anode sheet that has completed the pre-lithiation reaction is taken out, cleaned and dried to obtain the pre-lithiation silicon-oxygen anode; The cyclopentadienyl anion released from lithium molybdenum in organic solvents acts as an electron acceptor, undergoing a spontaneous redox reaction with silicon-oxygen anode materials.
2. The method according to claim 1, characterized in that: The concentration of the pre-lithiation solution is 0.05~0.1 mol / L.
3. The method according to claim 1, characterized in that: The organic solvent is at least one of ether solvents and carbonate solvents.
4. The method according to claim 3, characterized in that: The ether solvent is one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and dimethoxyethane; the carbonate solvent is one or more of dimethyl carbonate, diethyl carbonate, and ethylene carbonate.
5. The method according to claim 3, characterized in that: The organic solvent is a mixture of ether solvents and carbonate solvents in a volume ratio of 8:2 to 5:
5.
6. The method according to claim 1, characterized in that: The temperature of the pre-lithiation reaction is 10~40℃, and the reaction time is 10 s~30 min.
7. The method according to claim 6, characterized in that: The pre-lithiation reaction takes 1 to 10 minutes.
8. The method according to claim 1, characterized in that: The cleaning process uses dimethoxyethane or dimethyl carbonate.
9. The method according to claim 1, characterized in that: The silicon-oxygen negative electrode also contains a binder, which is polyacrylic acid or sodium alginate.
10. The application of a pre-lithiated silicon-oxygen anode prepared by the method of claim 1 in a lithium-ion battery.