Lithium metal negative electrode, lithium metal negative electrode preparation method and lithium ion battery
By coating the surface of a lithium substrate with a layer of nano-modified material, the problems of lithium dendrite growth and side reactions in lithium metal anodes were solved, resulting in higher cycle stability and energy density.
Patent Information
- Application Number
- CN202511474900.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2026-02-10
AI Technical Summary
During the electrochemical deposition process, uneven distribution of lithium ions in lithium metal anodes leads to the growth of lithium dendrites, posing a safety hazard. This is accompanied by volume changes and side reactions, affecting cycle stability.
A layer of nano-modified materials, including nano-silicon materials, nano-metal oxides, and nano-fluorides, is coated on the surface of a lithium substrate. Combined with modified polymers, this optimizes the lithium-ion diffusion path, forms a stable interface, blocks lithium dendrite growth, and reduces side reactions.
It significantly improves the cycle stability and safety of lithium metal anodes, optimizes lithium-ion transport, reduces active lithium loss, and increases energy density.
Smart Images
Figure CN121506876A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, and in particular to a lithium metal anode, a method for preparing a lithium metal anode, and a lithium-ion battery. Background Technology
[0002] Lithium-ion batteries based on graphite anodes are widely used in the new energy industry, covering portable devices, consumer electronics, electric vehicles, and large-scale energy storage systems. However, as the energy density of lithium-ion batteries approaches its theoretical limit, there is an urgent need for electrode materials with higher energy levels. Among anode materials, lithium metal anodes have significant advantages, with a theoretical specific capacity as high as 3860 mAh / g (far exceeding the 372 mAh / g of graphite anodes), and an extremely low electrochemical potential (-3.04 V vs. standard hydrogen electrode). Thinner lithium metal materials can provide higher volumetric / gravimetric energy density, which can not only enable higher energy densities for current liquid lithium batteries and future solid-state batteries, but also serve as an auxiliary material to supplement lithium in commercial silicon anodes. However, in the specific applications of lithium metal anodes, during the electrochemical deposition of lithium metal, the uneven lithium deposition due to the difference in local lithium ion flow distribution at the interface can easily lead to dendrite growth, which in turn can cause safety hazards such as internal short circuits and thermal runaway. Although its dissolution and deposition process is theoretically reversible and can achieve complete stripping or electroplating, it is accompanied by a large volume change. In addition, the active lithium in ultrathin lithium metal and alloy anodes is limited, and severe side reactions can also hinder their application. Summary of the Invention
[0003] To address the problem of uneven lithium deposition and lithium dendrite growth caused by ultrathin lithium metal anodes in existing technologies, this paper provides a lithium metal anode, a method for preparing a lithium metal anode, and a lithium-ion battery.
[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: On one hand, the present invention provides a lithium metal anode, comprising a lithium substrate and a modified material layer, wherein the modified material layer is disposed on the surface of the lithium substrate, and the modified material layer comprises nano-modifiers, wherein the nano-modifiers comprise one or more of nano-silicon materials, nano-metal oxides and nano-fluorides.
[0005] Optionally, the nano-silicon-containing material includes one or more of nano-silicon, micron-silicon, and nano-silica; and / or, The nano-metal oxide includes one or more of nano-lanthanum oxide, nano-zinc oxide, and nano-tin oxide; and / or, The nano-fluoride includes one or more of nano-fluorinated graphite, tin fluoride, and sodium fluoride.
[0006] Optionally, the modified material layer further includes a modified polymer, which is mixed with the nano-modifier; The modified polymer includes one or more of polydimethylsiloxane and PAO8.
[0007] Optionally, the percentage content of the modified polymer in the modified material layer is 0-1%.
[0008] Optionally, the mass percentage of the nano-modifier in the modified material layer is 2%-5%.
[0009] Optionally, the thickness of the lithium substrate is 50-200 μm, and the lithium substrate includes either lithium foil or alloy foil.
[0010] Optionally, the thickness of the modified material layer is 0.5-1 μm.
[0011] Optionally, the method for preparing the lithium metal anode includes the following operations: Obtain a suspension comprising nano-modifiers and modified polymers; The suspension is coated onto a rolling mill and then rolled onto a lithium substrate to obtain a pre-fabricated lithium metal anode. The modified polymer on the surface of the pre-fabricated lithium metal anode is cleaned to obtain the lithium metal anode.
[0012] Optionally, in the operation of "cleaning the modified polymer on the surface of the prefabricated lithium metal anode", a cleaning agent is used for cleaning, and the cleaning agent includes one or more of n-hexane, n-heptane, and n-octane.
[0013] On the other hand, the present invention provides a lithium-ion battery, including the lithium metal anode described above, or a lithium metal anode prepared by the method described above.
[0014] The beneficial effects of this application are as follows: The lithium metal anode provided in this application includes a lithium substrate and a modified material layer. The modified material layer is disposed on the surface of the lithium substrate and includes nano-modifiers. The nano-modifiers in the modified material layer have high specific surface area and surface active sites, which can uniformly adsorb lithium ions, optimize the lithium ion diffusion path, and avoid uneven lithium deposition caused by local concentration differences. In addition, the nano-modifiers can also play the role of a rigid physical barrier to block the growth of lithium dendrites. The stable interface formed between the nano-modifiers and the lithium substrate can effectively suppress the side reactions of lithium ions and electrolyte, reduce the loss of active lithium and the increase of interface impedance, and slow down the volume expansion during lithium dissolution and deposition, thereby significantly improving the cycle stability of the lithium metal anode. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the preparation process of the lithium metal anode provided by the present invention; Figure 2 These are test diagrams of the lithium symmetric batteries of Embodiment 1 and Comparative Example 1 provided by the present invention; Figure 3 These are full-cell test diagrams of Embodiment 7 and Comparative Example 1 provided by the present invention; Figure 4 These are full-cell test diagrams for Example 2 and Comparative Example 1; Figure 5 These are full-cell test diagrams for Example 3 and Comparative Example 1; Figure 6 These are full-cell test diagrams for Example 4 and Comparative Example 1; Figure 7 EIS test graphs for Example 7 and Comparative Example 1; Figure 8 This is a graph showing the XPS test results of the lithium battery negative electrode without cycling in Example 1; Figure 9 XPS graphs of 10 lithium-lithium symmetric cycling tests for Example 7 and Comparative Example 1. Figure 10 This is a SEM image of the uncycled lithium battery negative electrode from Example 1. Figure 11 This is a SEM image of the uncycled lithium battery negative electrode from Example 8. Figure 12 For Example 6 and Comparative Example 1, a surface deposition of 3 mAh / cm² was performed. 2 SEM image of lithium metal anode; Figure 13 This is a photograph of the actual object being tested in Example 5; Figure 14 This is a photograph of the actual object being tested in Example 6; Figure 15 This is a photograph of the actual object being tested in Example 8. Detailed Implementation
[0016] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
[0017] The present invention provides a lithium metal anode, comprising a lithium substrate and a modified material layer, wherein the modified material layer is disposed on the surface of the lithium substrate, and the modified material layer comprises nano-modifiers, wherein the nano-modifiers comprise one or more of nano-silicon materials, nano-metal oxides and nano-fluorides.
[0018] Specifically, the lithium metal anode provided in this application includes a lithium substrate and a modified material layer. The modified material layer is disposed on the surface of the lithium substrate and includes nano-modifiers. The nano-modifiers in the modified material layer have a high specific surface area and a large number of surface active sites, which can uniformly adsorb lithium ions, optimize the lithium ion diffusion path, and avoid uneven lithium deposition caused by local concentration differences. In addition, the nano-modifiers can also play the role of their own rigid physical barrier to block the growth of lithium dendrites. The stable interface formed by the nano-modifiers and the lithium substrate can effectively suppress the side reactions of lithium ions and electrolyte, reduce the loss of active lithium and the increase of interface impedance, and slow down the volume expansion during lithium dissolution and deposition, thereby significantly improving the cycle stability of the lithium metal anode.
[0019] In addition, when using nano-modified materials to coat the surface of lithium substrates, the wear resistance of the modified nanomaterials can effectively reduce the occurrence of roller sticking during roll coating.
[0020] In some embodiments, the nano-silicon-containing material includes one or more of nano-silicon, micron-silicon, and nano-silica; and / or, The nano-metal oxide includes one or more of nano-lanthanum oxide, nano-zinc oxide, and nano-tin oxide; and / or, The nano-fluoride includes one or more of nano-fluorinated graphite, tin fluoride, and sodium fluoride.
[0021] Specifically, the nano-silicon-containing material has a high theoretical specific capacity. By alloying with lithium, the nano-silicon-containing material improves the energy density of the anode, and the nanoscale silicon-containing material helps alleviate volume expansion and maintain structural stability. The nano-metal oxide, with its high ionic conductivity and chemical stability, can optimize the lithium-ion transport path, form a stable SEI film, and inhibit lithium dendrite growth. The fluorine element in the nano-fluoride has strong electronegativity, which can reduce interfacial impedance, improve interfacial stability, and enhance tolerance to the electrolyte, reducing side reactions. In other words, when the aforementioned nano-modified materials—nano-silicon-containing material, nano-metal oxide, and nano-fluoride—are applied to the lithium metal anode, they effectively improve the electrochemical performance and safety of the lithium metal anode by leveraging their respective physical barrier, ion transport regulation, and interfacial optimization functions.
[0022] In some embodiments, the modified material layer further includes a modified polymer, which is mixed with the nano-modifier; The modified polymer includes one or more of polydimethylsiloxane and PAO8.
[0023] The modified material layer incorporates a modified polymer, which is then mixed with nano-modifiers to achieve a synergistic effect. Specifically, the modified polymer polydimethylsiloxane (PDMS) possesses excellent flexibility and film-forming properties, allowing it to uniformly encapsulate the nano-modifiers and form a dense protective layer on the lithium substrate surface. This enhances the bonding force between the nano-modifiers and the lithium substrate. Simultaneously, the electronic insulation properties of PDMS can regulate the lithium-ion transport path, further inhibiting lithium dendrite growth and optimizing lithium deposition in conjunction with the nano-modifiers. Furthermore, the modified polymer can buffer the volume changes of lithium metal during deposition or dissolution, preventing the nano-modifiers from detaching or failing due to stress. It can also reduce interfacial impedance and minimize side reactions, thereby improving the cycle stability and safety of the lithium metal anode.
[0024] In some embodiments, the percentage content of the modified polymer in the modified material layer is 0-1%.
[0025] Specifically, the percentage content of the modified polymer in the modified material layer described in this application was determined through previous experimental verification. When the modified polymer added during the preparation of the lithium metal anode is used to prepare a suspension together with the nano-modifier, the modified polymer on the surface of the pre-made lithium metal anode is cleaned. After the cleaning process, the modified polymer can be completely removed or the residual amount of the modified polymer in the modified material layer is less than 1%, that is, after treatment, the percentage content of the modified polymer is in the range of 0-1%.
[0026] In some embodiments, the mass percentage of the nano-modifier in the modified material layer is 2%-5%.
[0027] Specifically, when the mass percentage of nano-modifiers in the modified material layer is controlled at 2%-5%, the nano-modifiers can be uniformly dispersed in the matrix of the modified polymer. This fully utilizes the high specific surface area and surface active sites of the nano-modifiers to effectively adsorb lithium ions and optimize ion diffusion paths, thereby improving the problems of uneven lithium deposition and dendrite growth. Furthermore, when the mass percentage of nano-modifiers in the modified material layer is 2%-5%, the nanoparticles in the nano-modifiers can form a stable rigid physical barrier, guiding uniform lithium nucleation. Simultaneously, they form a chemically stable interface layer with the lithium substrate, reducing direct contact between the electrolyte and lithium metal and lowering the frequency of side reactions. Moreover, this mass percentage of nano-modifiers can also avoid the problem of increased coating impedance or decreased flexibility caused by excessive agglomeration of nanoparticles. Thus, while ensuring efficient lithium ion transport and interfacial mechanical stability, it can also significantly improve the energy density of lithium-ion batteries, achieving an overall improvement in the cycle life and safety of the lithium metal anode.
[0028] Specifically, in the modified material layer, the mass percentage of the nano-modifier can be 2%, 3%, 4%, or 5%.
[0029] In some embodiments, the thickness of the lithium substrate is 50-200 μm, and the lithium substrate includes either lithium foil or alloy foil.
[0030] Specifically, controlling the thickness of the lithium substrate within the range of 50-200μm helps to reduce the amount of lithium metal used and lower costs. At the same time, lithium substrates within this thickness range, when used to make lithium metal anodes, can effectively mitigate volume changes during lithium deposition or dissolution.
[0031] High purity lithium foil reduces side reactions caused by impurities, ensures the interfacial stability between lithium metal and electrolyte, and reduces active lithium loss. Alloy foil (such as lithium-aluminum alloy) can improve lithium nucleation and reduce lithium dendrite growth by introducing other metal elements. At the same time, alloy foil can also enhance the mechanical strength of the material.
[0032] In some embodiments, the thickness of the modified material layer is 0.5-1 μm.
[0033] Specifically, in the lithium metal anode provided in this application, the thickness of the modified material layer is controlled within the range of 0.5-1 μm. If the thickness of the modified material layer is too thin, it is difficult to fully exert the physical barrier and ion diffusion regulation effects, and it is impossible to effectively suppress lithium dendrite growth and reduce interfacial side reactions. If the thickness of the modified material layer is too large, it will increase the migration resistance of lithium ions and increase the impedance. The 1 μm thickness set in this application can ensure that the nano-modifier and the modified polymer form a dense protective layer, which can suppress dendrites by uniformly dispersing lithium ions and optimizing nucleation sites, while maintaining good ion conductivity. At the same time, it can buffer the stress caused by the volume change of lithium metal, thereby taking into account the electrochemical performance, cycle stability and energy density of the anode, and thus improving the overall performance of the lithium metal anode.
[0034] In some embodiments, the method for preparing the lithium metal anode includes the following operations: Obtain a suspension comprising nano-modifiers and modified polymers; The suspension is coated onto a rolling mill and then rolled onto a lithium substrate to obtain a pre-fabricated lithium metal anode. The modified polymer on the surface of the pre-fabricated lithium metal anode is cleaned to obtain the lithium metal anode.
[0035] The method for preparing the lithium metal anode includes the following specific operations: The nano-modifier and the modified polymer were mixed and then placed in a ball mill. The mixture was ball-milled at a speed of 300 rpm, rotating forward and reverse 10 times each for 15 minutes each time, to obtain a suspension. The suspension is coated in a roller press in a glove box, and the lithium substrate is rolled into the roller press. The thickness is controlled to obtain a pre-fabricated lithium metal anode with a thickness of 15-50μm. The modified polymer on the surface of the pre-fabricated lithium metal anode is cleaned to obtain the lithium metal anode.
[0036] First, a suspension is prepared by combining the nano-modifier and the modified polymer, allowing the nanoparticles in the nano-modifier to be uniformly distributed within the modified polymer. This facilitates the formation of a uniformly distributed modified material layer. Second, roll coating is employed, using mechanical pressure to form a dense and firmly bonded modified material layer on the lithium substrate surface. This process allows for control over the coating thickness and density, ensuring close contact between the nano-modifier and the lithium substrate for physical barrier and ion control, while also enhancing interfacial bonding through the roll coating force, thus improving structural stability during cycling. Finally, the surface cleaning of the modified polymer removes unbound free polymer, preventing excessive polymer from negatively impacting ion conduction and resulting in a lithium metal anode with superior overall electrical performance.
[0037] Before rolling, a suspension is pre-coated onto the rolling equipment before rolling the lithium substrate. Compared to directly coating the lithium substrate surface during rolling, this method more effectively reduces the adhesion of the coating to the rolling equipment. Specifically, when the suspension is pre-coated on the rolling equipment, a buffer layer composed of nano-modifiers and modified polymers is formed on the roller surface. The nanoparticles in this buffer layer adsorb the solvent in the slurry due to their high specific surface area, reducing the interfacial tension between the slurry and the roller, making it easier for the slurry to transfer from the roller to the lithium substrate surface. At the same time, the viscosity of the modified polymer is reduced during pre-coating. During the coating process, the pre-coated suspension preferentially forms a reversible adsorption with the roller, rather than directly adhering to lithium metal or the substrate. When the roller is pressed, mechanical pressure is applied between the lithium substrate and the roller, and the pre-coated suspension will spread evenly under pressure. The rigid skeleton formed by the nano-modifier can support the slurry structure and reduce roller adhesion caused by slurry accumulation. In addition, the pre-coating operation can make the slurry distribution on the roller surface more uniform, avoiding local slurry accumulation caused by unevenness of the lithium substrate surface during direct coating, thereby improving the roller adhesion problem and enhancing the stability of the preparation process and the uniformity of the negative electrode coating.
[0038] In some embodiments, the operation of "cleaning the modified polymer on the surface of the prefabricated lithium metal anode" is carried out by cleaning with a cleaning agent, which includes one or more of n-hexane, n-heptane, and n-octane. Specifically, in the operation of cleaning the modified polymer on the surface of the pre-fabricated lithium metal anode, the cleaning agent has a good dissolving ability for the modified polymer, removes the free polymer on the surface of the lithium metal anode that is not bound to the nano-modifier, and avoids the problem of excessive modified polymer residue affecting ion conduction and large interfacial impedance; the cleaning agent provided in this application will not have side reactions with the lithium substrate or nano-modifier, ensuring the chemical stability of the anode interface during the cleaning process.
[0039] In another embodiment of the present invention, a lithium-ion battery is provided, comprising the lithium metal anode described above, or a lithium metal anode prepared by the method described above.
[0040] Specifically, the lithium-ion battery includes the lithium metal anode described in this application. The lithium metal anode comprises a lithium substrate and a modified material layer. The modified material layer is disposed on the surface of the lithium substrate and includes nano-modifiers. These nano-modifiers have high specific surface area and surface active sites, enabling uniform adsorption of lithium ions, optimizing the lithium ion diffusion path, and avoiding uneven lithium deposition due to local concentration differences. Furthermore, during the preparation of the lithium metal anode, optimization of the rolling operation reduces the occurrence of roller sticking problems during the rolling process. Controlling the residual amount of modified polymer ensures the stability of the anode structure and the consistency of the interface, reducing active lithium loss and side reactions.
[0041] The present invention will be further illustrated by the following examples.
[0042] Example 1 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including the following steps: Take 2g of nano-modified material (nano-silicon) and 50g of modified polymer (polydimethylsiloxane) and mix them. After mixing, put the mixture into a ball mill and ball mill it at a speed of 300rpm, rotating forward and reverse 10 times each for 15 minutes each time to obtain a suspension. The suspension is coated in a glove box roller press, and the lithium substrate is rolled into the roller press. The thickness is controlled (by controlling the rolling parameters of the roller press equipment) to prepare a pre-fabricated lithium metal anode. The modified polymer on the surface of the pre-fabricated lithium metal anode was cleaned with a cleaning agent (n-hexane). After cleaning, the percentage content of the modified polymer in the modified material layer was <0.1%, and the resulting lithium metal anode was obtained. The lithium substrate has a thickness of 50 μm, the modified material layer has a thickness of 1 μm, and the lithium metal anode has a thickness of 13 μm.
[0043] Example 2 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The nano-modified material is lanthanum oxide nanoparticles with a lithium metal thickness of 35 μm.
[0044] Example 3 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The nano-modified material is nano-fluorinated graphite with a lithium metal thickness of 35 μm.
[0045] Example 4 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The percentage of modified polymer in the unwashed modified material layer is 1%, and the lithium metal thickness is 35 μm.
[0046] Example 5 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The lithium substrate has a thickness of 50 μm, the modified material layer has a thickness of 1 μm, and the lithium metal anode has a thickness of 20 μm.
[0047] Example 6 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The lithium substrate has a thickness of 50 μm, the modified material layer has a thickness of 1 μm, and the lithium metal anode has a thickness of 25 μm.
[0048] Example 7 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The lithium substrate has a thickness of 50 μm, the modified material layer has a thickness of 1 μm, and the lithium metal anode has a thickness of 35 μm.
[0049] Example 8 This embodiment illustrates a lithium metal anode and a method for preparing a lithium metal anode disclosed in this invention, including most of the operations in Example 1, with the following differences: The lithium substrate has a thickness of 50 μm, the modified material layer has a thickness of 1 μm, and the lithium metal anode has a thickness of 40 μm.
[0050] Comparative Example 1 This comparative example is used to illustrate the lithium metal anode and its preparation method disclosed in this invention. It includes most of the operations in Example 1, but differs in that: The modified material layer of the lithium metal anode does not include nano-modifiers.
[0051] Preparation of lithium-ion batteries: Preparation of the positive electrode: Commercially available NCM622 particles, carbon nanotubes (CNTs), and NMP solvent were mixed in a ratio of 8:1:1. Zirconium beads were added and homogenized five times. The homogenized slurry was coated onto carbon-coated aluminum foil and then vacuum dried at 120°C for 24 hours to obtain the corresponding positive electrode.
[0052] The positive electrode and the lithium metal negative electrode prepared in Examples 1-8 and Comparative Example 1 were assembled to obtain lithium-ion batteries.
[0053] Performance testing The following performance tests were performed on Examples 1-8 and Comparative Example 1 prepared above: The Li-Li symmetry test was used to prepare a lithium-lithium symmetric battery using the obtained lithium metal anode, and the overpotential and cycle stability were tested.
[0054] For full-cell testing, the prepared NCM cathode 622 and lithium metal anode were used to fabricate a lithium-ion battery, and the capacity retention rate and corresponding specific capacity were tested.
[0055] EIS testing involves connecting batteries that have undergone 1 or 10 lithium-lithium symmetric cycle tests to an electrochemical workstation testing system and applying a small-amplitude AC signal. The response signal is measured at different frequencies, impedance data is recorded, and spectral characteristics are analyzed.
[0056] XPS testing involves placing an uncycled lithium metal anode and a lithium metal anode that has undergone 10 lithium-lithium symmetric cycling tests in a vacuum environment. After X-ray excitation, surface photoelectron signals are collected, and elemental and chemical state information is obtained through energy analysis. SEM testing showed that the uncycled lithium metal anode and the surface-deposited 3mAh / cm² electrode were compared. 2 After cleaning, drying and conductive treatment, the lithium metal anode is fixed on the sample stage. After vacuuming, the electron beam parameters are adjusted for scanning, and secondary electron or backscattered electron signals are collected for imaging. The surface morphology and composition information are then analyzed.
[0057] Figure 2 The test results of the lithium symmetric batteries of Example 1 and Comparative Example 1 show that, compared with the test results of the lithium-lithium symmetric batteries of Example 1 and Comparative Example 1, the lithium metal anode described in this application in Example 1 has a smaller overpotential and better cycle stability.
[0058] Figure 3 The full-cell test results of Example 7 and Comparative Example 1 are shown below. Comparing the full-cell test results of Example 7 and Comparative Example 1, it can be seen that Example 6, which uses the lithium metal anode described in this application, has better capacity retention and cycle stability compared to Comparative Example 1.
[0059] Figure 4The full-cell test results of Example 2 and Comparative Example 1 are shown below. Comparing the full-cell test results of Example 2 and Comparative Example 1, it can be seen that Example 2, which uses the lithium metal anode described in this application, has better capacity retention and cycle stability than Comparative Example 1, but is weaker than Example 7.
[0060] Figure 5 The full-cell test results of Example 3 and Comparative Example 1 are shown below. Comparing the full-cell test results of Example 3 and Comparative Example 1, it can be seen that Example 3, which uses the lithium metal anode described in this application, has better capacity retention and cycle stability than Comparative Example 1, but is weaker than Example 7.
[0061] Figure 6 The full-cell test results of Example 4 and Comparative Example 1 are shown below. Comparing the full-cell test results of Example 4 and Comparative Example 1, it can be seen that Example 4 uses the lithium metal anode described in this application, which has better capacity retention and cycle stability than Comparative Example 1, but the capacity retention is weaker than that of Example 7 and Example 3.
[0062] Figure 7 To compare the EIS test results of Example 7 and Comparative Example 1, it can be seen that the lithium-lithium symmetric battery prepared in Example 7 has lower impedance, a more stable SEI layer at the interface, and is more conducive to the passage of lithium ions.
[0063] XPS test results of the uncycled lithium battery anode from Example 1 Figure 8 As can be seen from the results, in Example 1, the lithium metal anode provided in this application was used for testing. The surface of the anode showed obvious nano-silicon elemental peak response and Si-O peaks were present.
[0064] XPS test results of 10 lithium-lithium symmetric cycling tests for comparison Example 7 and Comparative Example 1 Figure 9 It can be seen that the lithium metal anode prepared in Example 7 has a silicon content on the surface and a higher LiF content in the SEI component, resulting in a more stable interface layer.
[0065] SEM test results of the uncycled lithium battery anode from Example 1 Figure 10 As can be seen, the thickness of the prepared negative electrode is 13 μm.
[0066] SEM test results of the uncycled lithium battery anode from Example 8 Figure 11 As can be seen, the prepared negative electrode has a thickness of 40 μm, the surface nano-silicon particle modified material layer is maintained at 1 μm, and the elemental distribution is obvious.
[0067] Comparative Example 6 and Comparative Example 1 were subjected to surface deposition of 3 mAh / cm 2 SEM test results of lithium metal anode Figure 12It can be seen that the lithium deposition on the surface of the lithium metal anode prepared in Example 1 is smoother and thinner, proving that it is more dense.
[0068] Figure 13 The image shown is a physical example of Example 5, demonstrating its industrial feasibility for scaling up to the size of a soft pack under 20μm conditions.
[0069] Figure 14 The image shown is a physical representation of Example 6, demonstrating its advantage of scaling up to the size of a soft pack under 25μm conditions.
[0070] Figure 15 The image shown is a physical representation of Example 8, demonstrating its advantage of scaling up to the size of a soft pack under 40μm conditions.
[0071] 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, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A lithium metal anode, characterized in that, The invention includes a lithium substrate and a modified material layer, wherein the modified material layer is disposed on the surface of the lithium substrate, and the modified material layer includes nano-modifiers, wherein the nano-modifiers include one or more of nano-silicon materials, nano-metal oxides, and nano-fluorides.
2. The lithium metal anode according to claim 1, characterized in that, The nano-silicon-containing material includes one or more of nano-silicon, micron-silicon, and nano-silica; and / or, The nano-metal oxide includes one or more of nano-lanthanum oxide, nano-zinc oxide, and nano-tin oxide; and / or, The nano-fluoride includes one or more of nano-fluorinated graphite, tin fluoride, and sodium fluoride.
3. The lithium metal anode according to claim 1, characterized in that, The modified material layer also includes a modified polymer, which is mixed with the nano-modifier; The modified polymer includes one or more of polydimethylsiloxane, PAG, and PAO8.
4. The lithium metal anode according to claim 3, characterized in that, In the modified material layer, the percentage content of the modified polymer is 0-1%.
5. The lithium metal anode according to claim 1, characterized in that, In the modified material layer, the mass percentage of the nano-modifier is 2%-5%.
6. The lithium metal anode according to claim 1, characterized in that, The thickness of the lithium substrate is 50-200 μm, and the lithium substrate includes either lithium foil or alloy foil.
7. The lithium metal anode according to claim 1, characterized in that, The thickness of the modified material layer is 0.5-1 μm.
8. The method for preparing a lithium metal anode according to any one of claims 1-7, characterized in that, Includes the following operations: Obtain a suspension comprising nano-modifiers and modified polymers; The suspension is coated onto a rolling mill and then rolled onto a lithium substrate to obtain a pre-fabricated lithium metal anode. The modified polymer on the surface of the pre-fabricated lithium metal anode is cleaned to obtain the lithium metal anode.
9. The method for preparing a lithium metal anode according to claim 8, characterized in that, In the operation of "cleaning the modified polymer on the surface of the prefabricated lithium metal anode", a cleaning agent is used for cleaning, and the cleaning agent includes one or more of n-hexane, n-heptane, and n-octane.
10. A lithium-ion battery, characterized in that, The lithium metal anode includes the lithium metal anode as described in any one of claims 1-7, or the lithium metal anode prepared by the method described in any one of claims 8-9.