A modified metal electrode for inducing preferential growth of a metal electrodeposited metal in a specific crystal plane orientation, a metal battery and a preparation method thereof

Abstract

The application provides a modified metal electrode for inducing the growth of a preferential crystal face orientation of electrodepositing metal, a metal battery and a preparation method. The application spreads trifluoromethyltrimethylsilane on a metal surface, forms an artificial solid-state electrolyte interface film with high fluorine content on the metal surface through in-situ reaction of the trifluoromethyltrimethylsilane and the metal, and obtains a trifluoromethyltrimethylsilane modified metal electrode (a battery positive electrode or a battery negative electrode). The modified metal electrode can induce the growth of a preferential crystal face orientation of electrodepositing metal, and finally forms uniform, dendrite-free and flat block-shaped metal deposition.

Description

Technical Field

[0001] This invention relates to the field of metal battery and electrode design, specifically to a modified metal electrode, a metal battery, and a preparation method for inducing the directional growth of metal electrodeposited with a preferred crystal plane orientation. Background Technology

[0002] Metal batteries (including lithium, sodium, and potassium batteries) have attracted widespread attention due to their high energy and power densities, as well as their cleanliness, abundant reserves, and low cost, making them an important way to solve the current energy crisis and environmental pollution. For example, lithium metal anodes are valuable because of their extremely low electrochemical potential (-3.04 V vs. RHE) and low density (0.534 g / cm³). -3 ) and an extremely high theoretical specific capacity (3860mAh g) -1 This has attracted people's interest; sodium metal anodes have a high specific capacity (1166 mAh g / g). -1 Potassium metal anodes have attracted widespread attention due to their low redox potential (-2.71V vs. RHE) and abundant resources; they also possess high specific capacity (687mAh g / g). -1 The significant advantages of zinc and its low potential (-2.93V vs. RHE) make it a preferred anode material for high-energy-density and high-power-density batteries; zinc metal has also attracted attention due to its environmental friendliness, cleanliness, and safety. However, metal batteries also have some key problems, mainly manifested in dendrite formation, anode volume expansion, and performance degradation caused by the detachment of failed metal from the current collector.

[0003] Solid electrolyte interphase (SEI) membrane is an interfacial membrane composed of organic / inorganic substances generated on the surface of the metal anode through physical and (electro)chemical reactions between the metal anode and the electrolyte. This interfacial membrane plays the role of conducting ions and blocking electrons.

[0004] Existing methods for preparing SEI films cannot effectively induce the orientation and growth of metal crystals, resulting in minimal improvement in battery performance. Summary of the Invention

[0005] To address the problems of the prior art, this invention provides a modified metal electrode, a metal battery, and a preparation method for inducing the directional growth of metal crystals with dominant crystal plane orientations through electrodeposition, thereby solving the problems of existing metal electrodes being unable to induce the growth of metal crystal orientations and having limited performance improvement in batteries.

[0006] This invention is achieved through the following technical solution:

[0007] A method for preparing a modified metal electrode by inducing electrodeposition of metal with directional dominant crystal plane orientation involves spreading trifluoromethyltrimethylsilane on a metal surface, drying it, and generating an artificial solid electrolyte interface film in situ on the metal surface to obtain the modified metal electrode.

[0008] Preferably, the metal is lithium, sodium, zinc, aluminum, or magnesium.

[0009] Preferably, spreading trifluoromethyltrimethylsilane on the metal surface specifically involves dripping trifluoromethyltrimethylsilane onto the metal surface.

[0010] Preferably, the drying process specifically involves: drying at room temperature for 10-50 minutes, followed by heating at 60-100℃ for 2-24 hours.

[0011] Preferably, the metal surface is pre-polished.

[0012] Preferably, the trifluoromethyltrimethylsilane is pre-treated to remove water.

[0013] Furthermore, activated molecular sieves are used to remove water from trifluoromethyltrimethylsilane.

[0014] The modified metal electrode obtained by the preparation method described above is a metal electrode grown with induced electrodeposition and oriented preferential crystal planes.

[0015] A metal battery comprising a modified metal electrode grown by induced electrodeposition of a metal with directional dominant crystal plane orientation.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This invention involves spreading trifluoromethyltrimethylsilane on a metal surface and then reacting the trifluoromethyltrimethylsilane with the metal in situ to form a high-fluorine-content artificial solid electrolyte interphase (SEI) film on the metal surface, thus obtaining a trifluoromethyltrimethylsilane-modified battery electrode (positive or negative electrode). Taking lithium metal as an example, see [reference needed]. Figure 1As shown in Figure 2, the artificial SEI film formed by this method has a high concentration of LiF and -Si(CH3)3 organic components, and the components are uniformly distributed. This ensures high lithium-ion conductivity, allowing lithium ions to pass through uniformly and rapidly. This achieves a rapid and sufficient supply of lithium ions on the lithium metal substrate. Under these ideal conditions, the metal ion transport kinetics and electrocrystallization behavior can be controlled during the subsequent charging and discharging process of the metal battery. This allows metal ions to be transported rapidly and uniformly through the artificial SEI film, achieving uniform nucleation, deposition, and growth of metal atoms. This induces the orientation growth of metal crystals and inhibits dendrite growth, ultimately forming a uniform, dendrite-free, flat, blocky metal deposition. Lithium metal preferentially deposits as lithium deposition with a Li(110) crystal plane orientation, exhibiting a Li(110) texture. Lithium containing other fluorine-containing components or without trifluoromethyltrimethylsilane treatment, due to the uneven composition of ordinary SEI films and excessively high or low LiF content, results in insufficient lithium-ion supply or localized large-scale lithium-ion deposition. This causes lithium ions to deposit first at protruding areas during subsequent electron gain due to the "sharp effect," producing dendritic lithium deposits with Li(200) or Li(211) crystal plane orientation. Experimental results of this invention show that compared with lithium deposition with Li(200) or Li(211) crystal plane orientation, the lithium deposition with Li(110) crystal plane orientation of this invention produces batteries with better performance (cycle performance, rate performance, and stability). The preparation method of this invention uses readily available raw materials, has a mild and pollution-free reaction, low cost, and is easy to operate, making it suitable for large-scale production. It solves the problems of existing metal electrode modification, such as difficulty in inducing lithium metal crystal orientation growth, insignificant suppression of lithium dendrite growth, and insignificant improvement in battery performance, as well as technical problems such as complex operation, high cost, low safety, complex equipment, and low ionic conductivity. The modification method of this invention lays the foundation for the application of trifluoromethyltrimethylsilane in the field of electrochemistry, provides guidance for the modification of other similar materials and battery systems, and also provides a basis for in-depth analysis and theoretical explanation of the electrocrystallization behavior in metal batteries from a crystallographic perspective.

[0018] Furthermore, the method of the present invention is applicable to a variety of metals, including lithium, sodium, zinc, aluminum or magnesium, and the prepared lithium metal electrode exhibits excellent electrochemical performance in Li-Li symmetric cells and Li-LiFePO4 and Li-NCM811 full cells.

[0019] Furthermore, the molecular sieve after regeneration removes trace amounts of water and possible impurities from trifluoromethyltrimethylsilane, thus purifying the trifluoromethyltrimethylsilane and preventing the formation of oxides from the trace amounts of water when it comes into contact with metals, as well as other side reactions that may occur between the trace amounts of water and the metals. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating the mechanism of trifluoromethyltrimethylsilane-modified lithium metal-induced Li(110) orientation prepared in Example 1 of this invention, showing the crystallographic manipulation of Li(110) and Li(200) through SEI engineering: (a) Li in ordinary SEI + (a) Under harsh conditions of slow and uneven migration, the rapidly growing Li(200) plane induces vertically oriented Li(200) dendritic growth; (b) the SEI film of the present invention provides rapid and sufficient Li + Under ideal conditions, Li growth without dendrite deposition in planar Li(110) orientation follows the Bravais rule and the Curie-Wulff principle.

[0021] Figure 2 The diagram shows the trifluoromethyltrimethylsilane-modified lithium metal-induced Li(110) orientation prepared in Example 1 of this invention: (a) The advanced artificial SEI film has rapid and uniform surface and bulk ion diffusion, which is conducive to planar Li migration, Li(110) dominant crystal plane orientation and dendrite deposition; (b) Ordinary SEI film has slow and uneven lithium ion transport, resulting in lithium(200) crystal orientation and dendrite deposition.

[0022] Figure 3 The ball-and-stick model (a) of trifluoromethyltrimethylsilane used in Example 1 of the present invention and the FTIR spectra (b) of F3 and F3-Li.

[0023] Figure 4 The images show SEM images and EDX elemental mapping diagrams (a) of trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention, and SEI depth distribution diagrams of F1s of trifluoromethyltrimethylsilane-modified lithium metal (b) and lithium metal (c) after XPS etching and lithium deposition.

[0024] Figure 5 For XPS etching of the perfluorooctanoyl chloride (F) prepared in Comparative Example 1 of this invention 15 SEI depth distribution of F1s in modified lithium metal.

[0025] Figure 6 This is a calculated diagram of the HOMO and LUMO energy level orbitals of trifluoromethyltrimethylsilane used in Example 1 of the present invention and common solvents DOL and DME.

[0026] Figure 7Cryo-electron microscopy images of lithium metal and the artificial SEI film and lithium deposition of trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of the present invention: (a) Low-resolution image of lithium metal modified in Example 1; (b) High-resolution image and fast Fourier transform (FFT) image of lithium metal modified in Example 1; (c) Fast Fourier transform (FFT) image of lithium metal modified in Example 1; (d) Low-resolution image of lithium metal; (e) High-resolution image and fast Fourier transform image of lithium metal; (f) Selected area electron diffraction (SAED) image.

[0027] Figure 8 The images show the Young's modulus of the trifluoromethyltrimethylsilane-modified lithium metal SEI film and the pure lithium metal surface SEI film prepared in Example 1 of this invention.

[0028] Figure 9 This is an in-situ XRD pattern of the trifluoromethyltrimethylsilane-modified lithium metal deposition prepared in Example 1 of the present invention.

[0029] Figure 10 The following are 2D-XRD and XRD patterns of lithium metal modified with trifluoromethyltrimethylsilane prepared in Example 1 of this invention after deposition: (a) lithium metal after deposition modified with fluorine-containing reagent; (b) pure lithium metal after deposition; (c) pure lithium metal without deposition.

[0030] Figure 11 The perfluorooctanoyl chloride-modified lithium metal (F) prepared in Comparative Example 1 of this invention 15 XRD pattern of Li after deposition.

[0031] Figure 12 The lithium metal of this invention and the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 are compared at 1 mA / cm². -2 1mAh cm -2 SEM images after deposition / cycling under the following conditions: (a) Lithium metal modified in Example 1, deposited once; (b) Lithium metal modified in Example 1, cyclicated for 5 times; (c) Lithium metal modified in Example 1, deposited 10 times; (d) Lithium metal modified in Example 1, cyclicated for 20 times; (e) Lithium metal, deposited once; (f) Lithium metal, cyclicated for 5 times; (g) Lithium metal, deposited 10 times; (h) Lithium metal, cyclicated for 20 times; (i) Trifluoromethyltrimethylsilane modified lithium metal at 1 mA cm⁻¹ -2 5mAh cm -2 FIB-SEM images of deposits under specific conditions.

[0032] Figure 13 SEM images of lithium metal of the present invention and trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 after deposition / cycling at high current densities and deposition capacities: (a) SEM images of lithium metal modified in Example 1 at 3 mA cm⁻¹-2 1mAh cm -2 (b) Deposition once under the conditions of Example 1 modified lithium metal at 3 mA cm -2 1mAh cm -2 (c) Modified lithium metal from Example 1 was cycled for 3 cycles at 3 mA cm⁻¹. -2 3mAh cm -2 Deposition once under the conditions; (d) Modified lithium metal in Example 1 at 3 mA cm -2 3mAh cm -2 (e) Lithium metal under 3 mA cm -2 1mAh cm -2 (f) Lithium metal was deposited once under the conditions of 3 mA cm⁻¹. -2 1mAh cm -2 Cycle 3 times under the conditions; (g) lithium metal at 3mA cm -2 3mAh cm -2 Deposited once under the conditions; (h) lithium metal at 3mA cm -2 3mAh cm -2 Under the condition of cycling 3 times.

[0033] Figure 14 The contact angle (a), exchange current density (b), and nucleation growth overpotential (c) of the trifluoromethyltrimethylsilane-modified lithium metal and lithium metal electrolyte prepared in Example 1 of this invention are shown.

[0034] Figure 15 The lithium ion transference number is the trifluoromethyltrimethylsilane-modified lithium metal and lithium metal prepared in Example 1 of this invention.

[0035] Figure 16 The images show the impedance spectra of trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention and the lithium metal before and after five cycles.

[0036] Figure 17 Symmetric cell voltage-time curves of lithium metal and trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention: (a) 1 mA cm -2 and 1mAh cm -2 Under the conditions; (b) 3mA cm -2 and 1mAh cm -2 Under the following conditions; (c) 8mA cm -2 and 1mAh cm -2 conditions.

[0037] Figure 18The long-cycle performance and rate performance curves of trifluoromethyltrimethylsilane modified lithium metal, lithium metal assembled Li||NCM811 battery, and Li||LFP battery prepared in Example 1 of the present invention are as follows: (a) Long-cycle performance of Li||NCM811 battery; (b) Rate performance curve of Li||NCM811 battery; (c) Long-cycle performance of Li||LFP battery; (d) Rate performance curve of Li||LFP battery. Detailed Implementation

[0038] To further understand the present invention, the present invention will be described below with reference to embodiments. These descriptions are only for further explaining the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0039] This invention provides a method for preparing a modified metal electrode for induced electrodeposition of metal in a directional orientation, comprising the following steps:

[0040] 1) Polish the metal surface or leave it unpolished;

[0041] 2) The molecular sieve is regenerated by heating it in a muffle furnace at 250-500℃ for 5-24 hours;

[0042] 3) In a glove box, place an appropriate amount of molecular sieve in trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane;

[0043] 4) In a glove box, add, spin-coat, or spray water-free trifluoromethyltrimethylsilane onto the metal surface, dry at room temperature for 10-50 minutes, and heat at 60-100℃ for 2-24 hours to ensure complete drying. This will generate an artificial SEI film with a high fluorine content on the metal surface in situ, thus obtaining a modified metal electrode.

[0044] During the subsequent charging and discharging process of the metal battery, the artificial SEI film can induce the orientation growth of metal crystals, resulting in uniform, dendrite-free, and flat blocky metal deposition. However, metals that have not been modified with trifluoromethyltrimethylsilane, or those modified with other fluorine-containing reagents, cannot induce the orientation growth of metal crystals.

[0045] The metals mentioned in this invention include, but are not limited to, lithium, sodium, zinc, aluminum, and magnesium.

[0046] The metal batteries described in this invention include, but are not limited to, 2025 coin cells, common pouch cells, and metal deposition in electrochemical cells.

[0047] The molecular sieve mentioned in step 2) of this invention is a 4A-grade molecular sieve or a 5A-grade molecular sieve.

[0048] In step 4 of this invention, the amount of trifluoromethyltrimethylsilane added is 60 μL at a depth of 2 cm.-2 Lithium sheets (circular lithium sheets with a diameter of 1.6 μm and a thickness of 50 μm, 200 μm, or 600 μm) enable the uniform formation of an artificial SEI film on the lithium metal surface.

[0049] Step 4 of the present invention further includes: after washing and drying, assembling it into a metal battery, and depositing a metal layer on the surface of a metal substrate modified with trifluoromethyltrimethylsilane by an electrodeposition process, wherein the metal layer is made of lithium metal, sodium metal, zinc metal, aluminum metal or magnesium metal.

[0050] The metal battery of the present invention uses a metal electrode prepared by the above method. The metal electrode serves as the negative electrode or positive electrode of the battery. The metal battery is a lithium metal battery, a sodium metal battery, a zinc metal battery, an aluminum metal battery, or a magnesium metal battery.

[0051] In the following embodiments of the present invention, the electrolyte used in the electrodeposition process is a solution of lithium bis(trifluoromethanesulfonyl)ammonium dissolved in DOL and DME (1:1 volume ratio). In contrast, pure metallic lithium in the comparison sample also forms a fluorine-containing SEI film during the electrodeposition process in the electrolyte.

[0052] Example 1

[0053] (1) Use a knife to polish the lithium metal surface with a diameter of 1.4 cm and a thickness of 200 micrometers to make it a silvery-white metallic bright surface.

[0054] (2) The 5A grade molecular sieve was heated at 450℃ for 8 hours in a muffle furnace to achieve molecular sieve regeneration.

[0055] (3) In a glove box (argon atmosphere, water content less than 0.1ppm, oxygen content less than 0.1ppm), place 20 molecular sieves in 20ml of trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane.

[0056] (4) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), 60 μL of dehydrated trifluoromethyltrimethylsilane was dropped onto a polished lithium metal surface with a diameter of 1.6 cm and a thickness of 200 μm. The surface was dried at room temperature for 30 min and then heated at 60 °C for 12 h to ensure complete drying and to generate an artificial SEI film with a high fluorine content in situ on the lithium metal surface.

[0057] (5) During the subsequent charging and discharging process of lithium metal batteries, the artificial SEI film generated in situ by trifluoromethyltrimethylsilane can enable lithium metal to produce uniform, dendrite-free, flat block lithium deposition with Li(110) crystal orientation during lithium deposition.

[0058] Comparative Example 1

[0059] Based on Example 1, trifluoromethyltrimethylsilane was replaced with perfluorooctanoyl chloride to obtain a perfluorooctanoyl chloride-modified metal electrode (denoted as F). 15 -Li).

[0060] See Figure 3 As shown, Figure 3 The images show a ball-and-stick model (a) of trifluoromethyltrimethylsilane (F3) used in Example 1 of this invention, and the FTIR spectra (b) of F3 and F3-Li. The ball-and-stick model indicates that its molecular configuration is CF3Si(CH3)3, which contains F and Si atoms. The FTIR spectra show that both the pure F3 reagent and the SEI film formed after its reaction with Li contain a large number of -F and -Si(CH3)3 functional groups.

[0061] See Figure 4 As shown, Figure 4 The images show SEM images and EDX elemental mapping of the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention (a), and SEI depth distribution maps of F1s in trifluoromethyltrimethylsilane-modified lithium metal (b) and lithium metal (c) after XPS etching of lithium deposition. Image (a) shows that the surface of the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention is smooth, and the characteristic elements in trifluoromethyltrimethylsilane, such as C, F, and Si, are uniformly distributed, indicating that the trifluoromethyltrimethylsilane-modified lithium metal has a uniform fluorine-containing artificial SEI film. XPS results show that, compared to lithium metal (c), trifluoromethyltrimethylsilane-modified lithium metal (b) has a higher LiF content on the same ordinate scale. See also... Figure 5 As shown, Figure 5 The image shows the SEI depth distribution of F1s in the perfluorooctanoyl chloride-modified lithium metal prepared in Comparative Example 1 of this invention, etched by XPS. It indicates a high LiF content, suggesting that the SEI film generated by perfluorooctanoyl chloride treatment also contains a significant amount of F.

[0062] See Figure 6 As shown, Figure 6 This is a calculated graph of the HOMO and LUMO energy levels of trifluoromethyltrimethylsilane used in Example 1 of this invention, and common solvents 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME). The HOMO and LUMO energy levels of trifluoromethyltrimethylsilane are -8.25 and 1.75, respectively; those of DOL are -6.69 and 2.36, respectively; and those of DME are -6.83 and 2.34, respectively. This graph shows that compared to DOL and DME, trifluoromethyltrimethylsilane has a lower LUMO, and therefore reacts more readily with lithium metal, thereby generating an artificial SEI film with high fluorine content in situ.

[0063] See Figure 7 As shown, Figure 7 Cryo-electron microscopy images of lithium metal and the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention, as well as lithium deposition. The image shows that the lithium metal with the fluorine-containing artificial SEI film exhibits spherical deposition during initial deposition (a), and the artificial SEI film is only 30.5 nm thick (b), indicating that the artificial SEI film can promote the uniform spherical nucleation of lithium, which provides a basis for subsequent uniform lithium deposition and growth. Furthermore, thanks to the excellent fluorine-containing artificial SEI film, the trifluoromethyltrimethylsilane-modified lithium metal exhibits lithium nucleation with a (110) crystal plane orientation during the initial nucleation stage (c). The SEI film formed during the lithium metal electrodeposition process has a thickness of 97.2 nm (e), and the crystals formed during the electrodeposition process are dendritic (d) with a (200) crystal plane.

[0064] See Figure 8 As shown, Figure 8 The figures show the Young's modulus diagrams of the trifluoromethyltrimethylsilane-modified lithium metal SEI film prepared in Example 1 of this invention and the pure lithium metal SEI film. The diagrams indicate that the trifluoromethyltrimethylsilane-modified lithium metal SEI film has high mechanical strength, reaching 6.569 GPa, which can suppress dendrite formation. In contrast, the lithium metal SEI film has poor mechanical strength, insufficient to suppress dendrite formation, at 1.096 GPa.

[0065] See Figure 9 As shown, Figure 9 This is an in-situ XRD pattern of trifluoromethyltrimethylsilane-modified lithium metal deposition prepared in Example 1 of this invention. It shows that during lithium deposition, the trifluoromethyltrimethylsilane-modified lithium metal exhibits a gradually increasing intensity of the Li(110) crystal plane and a gradually decreasing intensity of the Li(200) and Li(211) crystal planes, indicating that the artificial SEI film formed by trifluoromethyltrimethylsilane can indeed induce the deposition of Li(110) crystals with a dominant crystal plane orientation in lithium metal.

[0066] See Figure 10 As shown, Figure 10 The figures show the 2D-XRD and XRD patterns of trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention, and the lithium metal after deposition. The figures indicate that the original lithium metal is (c) oriented with a (200) crystal plane, and after deposition at 5 mAh cm⁻¹... -2 After lithium, the lithium metal still has the (200) crystal plane orientation (b), while the trifluoromethyltrimethylsilane modified lithium metal deposited at 5 mAh cm⁻¹ -2 The lithium then exhibits a (110) crystal plane orientation (a). For lithium metal modified with perfluorooctanoyl chloride (F... 15 -Li), see below Figure 11 As shown, Figure 11The XRD pattern of lithium metal modified with perfluorooctanoyl chloride prepared in Comparative Example 1 of this invention after deposition; the crystal formed during the electrodeposition process is lithium deposition with the (211) crystal plane predominant. This proves that lithium metal modified with perfluorooctanoyl chloride cannot induce lithium to produce a dominant (110) crystal plane deposition, and only a specific fluorine-containing reagent (trifluoromethyltrimethylsilane) can induce lithium metal to produce the most stable dominant crystal plane Li (110) predominant lithium deposition.

[0067] See Figure 12 As shown, Figure 12 Lithium metal and the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention are used at a low current density of 1 mA cm⁻¹. -2 1mAh cm -2 The image shows SEM images after deposition / cycling under the specified conditions. This image demonstrates that, thanks to the excellent fluorine-containing artificial SEI film, trifluoromethyltrimethylsilane-modified lithium metal exhibits dendrite-free, bulky, uniform, and dense lithium deposition, with a deposition capacity of 5 mAh cm⁻¹. -2 Its thickness is 22.5 micrometers, close to the density of lithium and 5 micrometers / mAh cm⁻¹. -2 The lithium metal deposited by the method of this invention is dense; while lithium metal that has not been modified by the method of this invention, because it does not have this artificial SEI film, exhibits uneven, rough lithium deposition with whisker-like lithium dendrites during the lithium deposition process.

[0068] See Figure 13 As shown, Figure 13 SEM images of lithium metal and trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention after deposition at high current density. The image also shows that the trifluoromethyltrimethylsilane-modified lithium metal prepared in this invention exhibits dendrite-free, blocky, uniform, and dense lithium deposition, while conventional lithium metal exhibits uneven, rough, and whisker-like lithium dendrites during the lithium deposition process.

[0069] See Figure 14 As shown, Figure 14 The electrolyte contact angle, exchange current density, and nucleation growth overpotential of the trifluoromethyltrimethylsilane-modified lithium metal and lithium metal prepared in Example 1 of this invention are shown. The electrolyte contact angle of the trifluoromethyltrimethylsilane-modified lithium metal is 32.3°, the electrolyte contact angle of the lithium metal is 43.0°, and the exchange current density of the trifluoromethyltrimethylsilane-modified lithium metal is 0.206 mAh cm⁻¹. -2 The exchange current density of lithium metal is 0.132 mAh cm⁻¹. -2The figure shows that, compared to lithium metal, trifluoromethyltrimethylsilane-modified lithium metal exhibits a smaller contact angle with the electrolyte and demonstrates good wettability, thanks to the superior fluorinated artificial SEI film. Furthermore, it also exhibits a larger exchange current density and smaller lithium nucleation overpotential and lithium growth overpotential. This indicates that the fluorinated artificial SEI film generated by trifluoromethyltrimethylsilane-modified lithium metal achieves rapid kinetics.

[0070] See Figure 15 As shown, Figure 15 The values ​​represent the lithium-ion transference numbers of trifluoromethyltrimethylsilane-modified lithium metal and lithium metal prepared in Example 1 of this invention. Trifluoromethyltrimethylsilane-modified lithium metal exhibits a higher lithium-ion transference number of 0.66, while lithium metal has only 0.34, indicating that trifluoromethyltrimethylsilane modification improves the reaction kinetics.

[0071] See Figure 16 As shown, Figure 16 The images show the impedance spectra of trifluoromethyltrimethylsilane-modified lithium metal and lithium metal before and after five cycles, prepared in Example 1 of this invention. Trifluoromethyltrimethylsilane-modified lithium metal exhibits lower impedance before and after cycling, while lithium metal shows higher impedance. Notably, the impedance of trifluoromethyltrimethylsilane-modified lithium metal significantly decreases after cycling, which is related to the excellent SEI film.

[0072] See Figure 17 As shown, Figure 17 The figure shows the symmetrical battery voltage-time curves for lithium metal and the trifluoromethyltrimethylsilane-modified lithium metal prepared in Example 1 of this invention. As can be seen from the figure, at 1 mA cm⁻¹... -2 and 1mAh cm -2 Under the conditions described in this invention, trifluoromethyltrimethylsilane-modified lithium metal exhibits an ultra-long symmetric battery performance of up to 3500 hours, while unmodified lithium metal only has a symmetric battery performance of 200 hours; at 3 mA cm⁻¹ -2 and 1mAh cm -2 Under the conditions described above, the trifluoromethyltrimethylsilane-modified lithium metal of the present invention exhibits a symmetric cell performance of 350 h, while the unmodified lithium metal only has a symmetric cell performance of 150 h; at 8 mA cm -2 and 1mAh cm -2 Under the specified conditions, the trifluoromethyltrimethylsilane-modified lithium metal of the present invention exhibits an exceptionally long symmetric battery performance of 310 hours, while the unmodified lithium metal only achieves a symmetric battery performance of 40 hours. This figure demonstrates that the battery composed of the trifluoromethyltrimethylsilane-modified lithium metal of the present invention exhibits very good stability, significantly superior to that of the unmodified lithium metal.

[0073] See Figure 18As shown, Figure 18 The images show the long-cycle performance and rate performance curves of the Li||LFP and Li||NCM811 batteries assembled with trifluoromethyltrimethylsilane-modified lithium metal, pure lithium metal, and lithium metal prepared in Example 1 of this invention. At a current density of 1C, F3-Li||NCM811 exhibits a cycle life of up to 160 cycles, while maintaining a capacity of 160 mAh g⁻¹. -1 Lithium metal exhibits significant capacity degradation after only 30 cycles. When cycling at current densities gradually increasing from 0.1C to 5C and then back to 0.1C, F3-Li||NCM811 still demonstrates higher specific capacity and cycle stability. At a current density of 1C, F3-Li||LFP achieves a cycle life of up to 700 cycles, maintaining a capacity of 150 mAh g⁻¹. -1 Lithium metal exhibits significant degradation after only 200 cycles. When the current density is gradually increased from 0.1C to 5C and then cycled back to 0.1C, F3-Li||811 still maintains higher specific capacity and cycle stability. This figure shows that trifluoromethyltrimethylsilane modification provides a negative electrode with high deposition-stripping reversibility, improving the discharge specific capacity, cycle stability, and coulombic efficiency of Li||LFP and Li||NCM811 full cells.

[0074] Example 2

[0075] (1) Use a polytetrafluoroethylene rolling pin to polish the lithium metal surface into a silvery-white metallic bright surface by rolling. Then use a tablet press with a diameter of 1.4cm to press the rolled lithium into a round piece with a diameter of 1.4cm.

[0076] (2) The 5A grade molecular sieve was regenerated by heating it in a muffle furnace at 280°C for 24 hours.

[0077] (3) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), place 15 molecular sieves in 10 ml of trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane.

[0078] (4) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), 100 μL of dehydrated trifluoromethyltrimethylsilane was dropped onto a polished lithium metal surface with a diameter of 1.4 cm and a thickness of 200 μm. The surface was dried at room temperature for 60 min and then heated at 80 °C for 4 h to ensure complete drying and to generate an artificial SEI film with a high fluorine content in situ on the lithium metal surface.

[0079] (5) During the subsequent charging and discharging process of lithium metal batteries, the artificial SEI film can enable lithium metal to produce uniform, dendrite-free, flat, blocky lithium deposits with Li(110) crystal orientation during lithium deposition. However, unmodified lithium metal, without this artificial SEI film, exhibits non-uniform, uneven lithium deposition with beard-like lithium dendrites during lithium deposition.

[0080] Example 3

[0081] (1) Use a knife to polish the lithium metal surface with a diameter of 1.6 cm and a thickness of 600 micrometers to make it a silvery-white metallic bright surface.

[0082] (2) The 5A grade molecular sieve was regenerated by heating at 300℃ for 12 hours in a muffle furnace.

[0083] (3) In a glove box (argon atmosphere, water content less than 0.1ppm, oxygen content less than 0.1ppm), place 20 molecular sieves in 20ml of trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane.

[0084] (4) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), 100 μL of water-removed trifluoromethyltrimethylsilane was dropped onto a polished lithium metal surface with a diameter of 1.6 cm and a thickness of 600 μm. The surface was dried at room temperature for 60 min and then heated at 60 °C for 24 h to ensure complete drying and to generate an artificial SEI film with a high fluorine content in situ on the lithium metal surface.

[0085] (5) During the subsequent charging and discharging process of lithium metal batteries, the artificial SEI film can enable lithium metal to produce uniform, dendrite-free, flat, blocky lithium deposits with Li(110) crystal orientation during lithium deposition. However, unmodified lithium metal, without this artificial SEI film, exhibits non-uniform, uneven lithium deposition with beard-like lithium dendrites during lithium deposition.

[0086] Example 4

[0087] (1) The sodium metal surface is polished to a silvery-white metallic shine by rolling with a polytetrafluoroethylene rolling pin. The rolled sodium is then pressed into round sheets with a diameter of 1.4 cm by a tablet press with a diameter of 1.4 cm.

[0088] (2) The 5A grade molecular sieve was regenerated by heating at 320℃ for 12 hours in a muffle furnace.

[0089] (3) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), place 30 molecular sieves in 30 ml of trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane.

[0090] (4) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), 60 μL of water-removed trifluoromethyltrimethylsilane was dropped onto the polished sodium metal surface, dried at room temperature for 60 min, and heated at 100 °C for 4 h to make it completely dry, so that an artificial SEI film with a high fluorine content was generated in situ on the sodium metal surface.

[0091] (5) During the subsequent charging and discharging process of sodium metal batteries, the artificial SEI film can make sodium metal deposit in a uniform, dendrite-free, flat block shape. However, unmodified sodium metal, without this artificial SEI film, exhibits an uneven, uneven sodium deposition with sodium dendrites during the sodium deposition process.

[0092] Example 5

[0093] (1) Use a polytetrafluoroethylene rolling pin to polish the potassium metal surface into a silvery-white metallic bright surface by rolling. Then use a tablet press with a diameter of 1.4cm to press the rolled potassium into a round tablet with a diameter of 1.4cm.

[0094] (2) The 5A grade molecular sieve was regenerated by heating at 320℃ for 12 hours in a muffle furnace.

[0095] (3) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), place 30 molecular sieves in 30 ml of trifluoromethyltrimethylsilane to remove trace amounts of water contained in the trifluoromethyltrimethylsilane.

[0096] (4) In a glove box (argon atmosphere, water content less than 0.1 ppm, oxygen content less than 0.1 ppm), 60 μL of water-removed trifluoromethyltrimethylsilane was dropped onto the polished potassium metal surface, dried at room temperature for 60 min, and heated at 60 °C for 4 h to make it completely dry, so that an artificial SEI film with a high fluorine content was generated in situ on the potassium metal surface.

[0097] (5) During the subsequent charging and discharging process of potassium metal batteries, the artificial SEI film can make potassium metal deposit uniformly, without dendrites, and in a flat block shape. However, unmodified potassium metal, without this artificial SEI film, exhibits uneven, uneven potassium deposition with potassium dendrites during the potassium deposition process.

[0098] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a modified metal electrode that induces the directional growth of metal with dominant crystal plane orientation by electrodeposition, characterized in that, Trifluoromethyltrimethylsilane is spread on a metal surface and dried to generate an artificial solid electrolyte interface film in situ on the metal surface, thus obtaining a modified metal electrode; wherein the metal is lithium.

2. The method for preparing a modified metal electrode by induced electrodeposition of metal with directional dominant crystal plane orientation according to claim 1, characterized in that, The process of spreading trifluoromethyltrimethylsilane on the metal surface specifically involves adding trifluoromethyltrimethylsilane dropwise onto the metal surface.

3. The method for preparing a modified metal electrode with induced electrodeposition of metal with directional dominant crystal plane orientation according to claim 1, characterized in that, The drying process specifically involves: drying at room temperature for 10-50 minutes, followed by heating at 60-100℃ for 2-24 hours.

4. The method for preparing a modified metal electrode with induced electrodeposition of metal with directional dominant crystal plane orientation according to claim 1, characterized in that, The metal surface is polished beforehand.

5. The method for preparing a modified metal electrode by induced electrodeposition of metal with directional dominant crystal plane orientation according to claim 1, characterized in that, Trifluoromethyltrimethylsilane is pre-treated to remove water.

6. The method for preparing a modified metal electrode with induced electrodeposition of metal with directional dominant crystal plane orientation according to claim 5, characterized in that, Activated molecular sieves were used to remove water from trifluoromethyltrimethylsilane.

7. A modified metal electrode obtained by the preparation method according to any one of claims 1-6, characterized by induced electrodeposition of metal with directional dominant crystal plane orientation.

8. A metal battery comprising a modified metal electrode grown by induced electrodeposition of a metal with directional dominant crystal plane orientation as described in claim 7.

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