Nitrogen-rich solid electrolyte interface, preparation method and application of nitrogen-rich solid electrolyte interface in lithium metal battery
By introducing catalytic active materials into the negative electrode of the lithium metal battery, catalyzing nitrate decomposition and forming a nitrogen-rich SEI layer, the problems of lithium dendrites growth and SEI film instability are solved, and the cycle life and safety of the battery are improved.
Patent Information
- Application Number
- CN202510314178.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-17
- Publication Date
- 2025-06-13
AI Technical Summary
During the charging and discharging process, existing lithium metal batteries have problems such as lithium dendrites growth and solid electrolyte interface (SEI) film instability, which affects the cycle life and safety of the battery.
By introducing catalytically active materials, the decomposition of nitrate components is directionally catalyzed, the formation of nitrogen-rich SEI layers is promoted, inorganic components are increased, lithium ion transport is accelerated, and dendrites are inhibited.
The transmission characteristics and structural stability of the lithium ions of the SEI film are significantly improved, the cycle life of the lithium metal battery is extended, and the safety is improved.
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Figure CN120149596A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of lithium metal batteries, and particularly relates to a nitrogen-rich solid electrolyte interface, a preparation method thereof, and an application thereof in lithium metal batteries. Background Art
[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.
[0003] Lithium metal batteries have advantages such as high energy density, but there are problems such as lithium dendrite growth and instability of the solid electrolyte interface (SEI) film during the charge and discharge process of the lithium metal anode, which seriously affect the cycle life and safety of the battery. As an effective electrolyte additive, nitrate can form a nitrogen-rich SEI layer on the lithium metal surface. During discharge, the dissociated nitrate anions (NO 3 - ) are reduced and then form Li 3 N, increasing the content of inorganic components in the SEI film. Li 3 N has high lithium ion conductivity and mechanical strength, which is beneficial to improving the lithium ion transport characteristics and structural stability of the SEI film. Therefore, enhancing the decomposition kinetics of NO 3 - and optimizing the content and distribution of inorganic and organic components are extremely important for constructing a high-performance SEI film and realizing a long-life lithium metal battery.
[0004] However, in a conventional battery system, the decomposition process of NO 3 - is relatively slow, resulting in its difficult to fully play a role in improving the performance of the SEI film. Therefore, there is an urgent need to develop an effective method to promote and regulate the decomposition behavior of nitrate, thereby constructing an efficient and stable SEI layer and finally obtaining a high-performance lithium metal battery. Summary of the Invention
[0005] To solve the above problems, the present invention provides a nitrogen-rich solid electrolyte interface (SEI), a preparation method thereof, and an application thereof in lithium metal batteries. The present invention promotes the formation of a nitrogen-rich SEI layer by introducing a catalytic active material to directionally catalyze the decomposition of nitrate components, increases the inorganic components, accelerates the lithium ion transport, inhibits dendrite growth, and improves the cycle life.
[0006] Specifically, the present invention adopts the following technical solutions:
[0007] In the first aspect of the present invention, a nitrogen-rich solid electrolyte interface is provided. The composition of the nitrogen-rich solid electrolyte interface includes lithium nitride and lithium fluoride, which are obtained by catalytic decomposition of an electrolyte containing nitrate by a metal single-atom catalyst.
[0008] The metal single-atom catalyst is obtained by reacting a carbon support and a metal salt. The carbon support includes heteroatom-doped carbon materials, conductive carbon black, and carbon nanotubes. The metal salt is selected from one or more of metal chlorides, metal nitrates, and metal acetylacetonate compounds, and the metal is selected from at least one of iron, cobalt, nickel, manganese, vanadium, ruthenium, rhodium, palladium, silver, iridium, platinum, and gold.
[0009] The electrolyte containing nitrate includes an electrolyte additive and a lithium salt. The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorooxalate borate, lithium bis(oxalato)borate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The electrolyte additive is selected from one or more of lithium nitrate, sodium nitrate, and potassium nitrate.
[0010] Preferably, the heteroatom in the heteroatom-doped carbon material is selected from at least one of nitrogen, phosphorus, and sulfur, and is specifically obtained by high-temperature pyrolysis of a carbon-containing precursor and a heteroatom compound. The carbon-containing precursor is selected from at least one of glucose, citric acid, polyacrylonitrile, phenolic resin, cellulose, lignin, and chitosan. The heteroatom compound is selected from at least one of urea, melamine, polyaniline, thiourea, carbon disulfide, phosphoric acid, ammonium dihydrogen phosphate, and thioacetamide.
[0011] In the second aspect of the present invention, a method for preparing the above nitrogen-rich solid electrolyte interface is provided, specifically: using a lithium salt solution added with an electrolyte additive as the electrolyte of a lithium metal battery, and using a current collector coated with a metal single-atom catalyst as the negative electrode of the lithium metal battery. During the charge-discharge cycle, a solid electrolyte interface rich in lithium nitride and lithium fluoride is prepared by in-situ decomposition of nitrate at the negative electrode.
[0012] Preferably, the method for preparing the negative electrode of the lithium metal battery includes the following steps:
[0013] S1. Mix and dissolve a carbon-containing precursor, a heteroatom compound, and a metal salt, and stir dry. Perform a high-temperature pyrolysis reaction under an inert atmosphere to obtain a metal single-atom catalyst.
[0014] S2. Mix the metal single-atom catalyst and a binder to obtain a catalyst slurry.
[0015] S3. Coat the catalyst slurry on a current collector, dry it, and cut it into pieces to obtain a current collector with a catalyst layer.
[0016] S4. Electrodeposit lithium metal onto the surface of the catalytic layer to obtain the product.
[0017] Further preferably, in step S1, the inert atmosphere is selected from one of nitrogen and argon, the temperature of the heating reaction is 600 - 1000 °C, and the time is 3 - 8 h.
[0018] Further preferably, in step S2, the mass ratio of the carbon-supported single-atom catalyst to the binder is 1:1 - 10:1, preferably 9:1.
[0019] Further preferably, in step S3, the current collector is selected from one or more of stainless steel foil, aluminum foil, copper foil, and carbon paper; the thickness of the coating is 8 - 12 μm, preferably 10 μm.
[0020] Further preferably, in step S4, the specific electrodeposition process is: the current density is 0.5 - 1.5 mA cm -2 , and the electrodeposition time is 3 - 6 h.
[0021] Preferably, the positive electrode plate includes a positive current collector and a positive electrode material layer on the surface of the positive current collector; the positive current collector is selected from one or more of stainless steel foil, aluminum foil, copper foil, and carbon paper.
[0022] Further preferably, the positive electrode active material included in the positive electrode material layer is selected from one or more of lithium iron phosphate, lithium cobaltate, ternary materials, and lithium-rich manganese-based positive electrode materials.
[0023] Preferably, the nitrate electrolyte additive is selected from one or more of lithium nitrate, sodium nitrate, and potassium nitrate.
[0024] In the third aspect of the present invention, a lithium metal negative electrode is provided, which includes in-situ generating the nitrogen-rich solid electrolyte interface described in the first aspect.
[0025] In the fourth aspect of the present invention, a lithium metal battery is provided, and the nitrogen-rich solid electrolyte interface described in the first aspect is formed in-situ at the negative electrode of the lithium metal battery during the charge and discharge cycle process.
[0026] In the fifth aspect of the present invention, an application of the nitrogen-rich solid electrolyte interface described in the first aspect in a lithium metal battery is provided.
[0027] The beneficial effects of the above one or more technical solutions are as follows:
[0028] (1) By introducing a metal catalyst at the negative electrode of the battery, the present invention can efficiently catalyze the decomposition of nitrate, significantly improve the utilization rate of nitrate, promote the formation of the nitrogen-rich SEI layer, effectively inhibit the growth of lithium dendrites, and improve the cycle stability and safety of the battery.
[0029] (2) The preparation method of the negative electrode sheet of the present invention is simple, low in cost, easy for large-scale production, and has good industrial application prospects.
[0030] (3) The lithium metal battery applying the negative electrode of the present invention has high energy density, long cycle life and good rate performance, and can meet the requirements of high-performance batteries. Description of the Drawings
[0031] Figure 1 It is a structure and morphology characterization diagram of the cobalt (Co / NC) catalyst supported on nitrogen-doped carbon material in Example 1 of the present invention. Among them, a) is the XRD pattern, b) is the aberration-corrected transmission electron microscope image, and c) is the HRTEM EDS mapping image;
[0032] Figure 2 It is the first-cycle CV curve test diagram of the asymmetric batteries in Examples 1-3 and Comparative Examples 1 and 3 of the present invention;
[0033] Figure 3 It is the long-cycle performance test diagram of the symmetric batteries in Examples 1-3 and Comparative Examples 1 and 3 of the present invention;
[0034] Figure 4 It is the long-cycle performance test diagram of the full batteries assembled in Example 4 and Comparative Example 2 of the present invention. Detailed Embodiments
[0035] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.
[0036] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments.
[0037] Example 1: This example provides a lithium metal symmetric battery assembled with a lithium metal negative electrode, including the following steps:
[0038] The first step: Dissolve 1.625 g of glucose, 10 g of urea and 100 mg of cobalt chloride in 30 mL of deionized water, heat to 900 °C, stir and evaporate to dryness, and sinter at 900 °C for 5 h under an argon atmosphere. Grind the obtained product evenly to obtain a cobalt single-atom material supported on nitrogen-doped carbon;
[0039] The second step: Mix the above product with a sodium carboxymethylcellulose (CMC) binder in a ratio of 9:1 to prepare a slurry;
[0040] The third step: Coat the slurry on the current collector, and the coating thickness is 10 μm;
[0041] Step 4: Assemble the current collector coated with the catalyst and the lithium metal anode, and deposit lithium metal on the current collector at a current density of 1 mA cm -2 for 5 h to obtain the lithium metal anode;
[0042] Step 5: Assemble the above lithium metal anode into a lithium metal symmetric battery.
[0043] Example 2:
[0044] The difference between this example and Example 1 is that nickel chloride is added in the first step.
[0045] Example 3:
[0046] The difference between this example and Example 1 is that iron chloride is added in the first step.
[0047] Example 4:
[0048] The difference between this example and Example 1 is that in this example, the lithium metal anode in the fifth step is assembled with lithium iron phosphate to form a lithium metal anode full cell.
[0049] Comparative Example 1:
[0050] The difference between this comparative example and Example 1 is that the current collector is not modified:
[0051] Step 1: Assemble the copper current collector and the lithium metal anode, and deposit lithium metal on the current collector to obtain the lithium metal anode;
[0052] Step 2: Assemble the above lithium metal anode into a lithium metal symmetric battery.
[0053] Comparative Example 2:
[0054] The difference between this comparative example and Comparative Example 1 is that in the second step, the lithium metal anode is assembled with lithium iron phosphate to form a lithium metal anode full cell.
[0055] Comparative Example 3:
[0056] The difference between this comparative example and Comparative Example 1 is that a nitrogen-doped carbon material is used to modify the current collector:
[0057] Step 1: Dissolve 1.625 g of glucose and 10 g of urea in 30 mL of deionized water, heat to 80 °C, stir and evaporate to dryness, sinter at 900 °C for 5 h under an argon atmosphere, and grind the obtained product evenly to obtain the nitrogen-doped carbon material;
[0058] Step 2: Mix the above product and sodium carboxymethyl cellulose (CMC) binder in a ratio of 9:1 to prepare a slurry;
[0059] Step 3: Coat the slurry on the current collector with a coating thickness of 10 μm;
[0060] Step 4: Assemble the carbon-coated current collector with the lithium metal anode and charge the lithium metal at 1 mA cm -2 The lithium metal anode was obtained by deposition on the current collector for 5 h at a current density of ;
[0061] Step 5: Assemble the above-mentioned lithium metal negative electrode into a lithium metal symmetric battery.
[0062] Material characterization
[0063] In this example, the nitrogen-doped carbon-supported cobalt single-atom material obtained in the first step of Example 1 was characterized by X-ray diffraction (XRD), spherical aberration-corrected transmission electron microscopy, and high-resolution transmission electron microscopy (HRTEM).
[0064] Depend on Figure 1 The XRD patterns in the graph show that the nitrogen-doped carbon material is an amorphous structure. After loading cobalt, the amorphous state does not change and no crystalline peaks related to cobalt species appear, indicating that cobalt metal may exist in the form of single atoms, amorphous, ultra-small nanoparticles or highly diluted forms.
[0065] Further combined with the spherical aberration corrected transmission electron microscopy image, it can be seen that the Co element exists in the form of a single atom;
[0066] The EDS mapping surface distribution shows that Co single atoms are uniformly loaded on the two-dimensional nitrogen-doped carbon nanosheets.
[0067] Electrochemical performance test
[0068] The electrolyte used was LiTFSI dissolved in a mixed solvent of dimethyl ether and dioxolane (DME:DOL was a 1:1 volume ratio solvent) and contained 2% LiNO 3 Additives: The reduction and decomposition of each electrolyte component during the formation of the initial SEI layer can be observed through the first-cycle discharge CV curve.
[0069] like Figure 2 As shown in the figure, as the discharge progresses, at the reduction potential ≈ 1.7 V, the adsorbed LiNO 3 Decomposed into Li 3 N and a series of other nitrides. Among them, the introduction of Co / NC in Example 1 greatly promoted the reaction and promoted Li 3 The large amount of N is generated, which is manifested as the most significant reduction decomposition peak at 1.7 V; while in Comparative Example 1, Comparative Example 3, Examples 2 to 3, Cu, NC-Cu, Fe / NC, and Ni / NC show no obvious LiNO 3The reduction peak indicates that insufficient decomposition occurred on the surfaces of these electrodes.
[0070] In addition, the reduction decomposition of LiTFSI occurred at around 1.2 V, and a relatively obvious reduction decomposition peak also appeared on the surface of the Co / NC electrode, indicating that Co / NC can also promote the decomposition of LiTFSI and the formation of LiF simultaneously, realizing the construction of an SEI layer rich in Li 3 N and LiF with high mechanical stability and electrochemical stability.
[0071] As Figure 3 shown, under the conditions of a current density of 1 mA cm -2 , areal capacity of 1 mAh cm -2 , in Example 2, the Fe / NC had 180 cycles and a time of 450 h, in Example 3, the Ni / NC had 165 cycles and a time of 410 h, in Comparative Example 1, the pure copper had 75 cycles and a time of 190 h, and in Comparative Example 3, the NC had 110 cycles and a time of 270 h. Different from the above examples and comparative examples, due to the SEI layer rich in nitrogen and fluorine components formed on the surface of Co / NC, the cycle stability of the lithium metal in Example 1 was significantly improved, and it could stably cycle 1000 times with a cycle time exceeding 2500 h.
[0072] As Figure 4 shown, in Example 4, when the lithium metal anode with an SEI layer rich in nitrogen and fluorine components was matched with the lithium iron phosphate cathode, the specific capacity after cycling 500 times at a current density of 1 C could still reach 109.1 mAh g -1 , while in Comparative Example 2, the specific capacity after cycling 500 times was 85.9 mAh g -1 , indicating that the SEI layer rich in nitrogen and fluorine components greatly improved the capacity retention rate of the lithium iron phosphate lithium metal battery.
[0073] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A nitrogen-rich solid electrolyte interface, characterized in that: The components of the solid electrolyte interface include lithium nitride and lithium fluoride, and the lithium nitride and lithium fluoride are obtained by decomposing a nitrate-containing electrolyte catalyzed by a metal single atom catalyst; The metal single atom catalyst is obtained by reacting a carbon carrier and a metal salt, wherein the carbon carrier includes a heteroatom-doped carbon material, conductive carbon black, and carbon nanotubes; the metal salt is selected from one or more of metal chlorides, metal nitrates, and acetylacetone metal compounds, wherein the metal is selected from at least one of iron, cobalt, nickel, manganese, vanadium, ruthenium, rhodium, palladium, silver, iridium, platinum, and gold; The nitrate-containing electrolyte includes an electrolyte additive and a lithium salt, wherein the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide; and the electrolyte additive is selected from one or more of lithium nitrate, sodium nitrate, and potassium nitrate.
2. The nitrogen-rich solid electrolyte interface according to claim 1, characterized in that The heteroatom in the heteroatom-doped carbon material is selected from at least one of nitrogen, phosphorus, and sulfur, and is specifically obtained by high-temperature pyrolysis of a carbon-containing precursor and a heteroatom compound. The carbon-containing precursor is selected from at least one of glucose, citric acid, polyacrylonitrile, phenolic resin, cellulose, lignin, and chitosan, and the heteroatom compound is selected from at least one of urea, melamine, polyaniline, thiourea, carbon disulfide, phosphoric acid, diammonium phosphate, and thioacetamide.
3. A method for preparing a nitrogen-rich solid electrolyte interface according to any one of claims 1 to 2, characterized in that: Specifically: A lithium salt solution with added electrolyte additives is used as the electrolyte of the lithium metal battery, and a current collector coated with a metal single atom catalyst is used as the negative electrode of the lithium metal battery. During the charge and discharge cycle, a solid electrolyte interface rich in lithium nitride and lithium fluoride is produced through the in-situ decomposition of nitrate at the negative electrode.
4. The preparation method according to claim 3, characterized in that: The method for preparing the negative electrode of the lithium metal battery comprises the following steps: S1, mixing and dissolving a carbon-containing precursor, a heteroatom compound and a metal salt, stirring to dryness, and performing a high-temperature pyrolysis reaction under an inert atmosphere to obtain a metal single-atom catalyst; S2, mixing the metal single atom catalyst and the binder to obtain a catalyst slurry; S3, coating the catalyst slurry on the current collector, drying and cutting into pieces to obtain a current collector containing a catalyst layer; S4, electro-depositing lithium metal onto the surface of the catalyst layer.
5. The preparation method according to claim 4, characterized in that: In step S1, the inert atmosphere is selected from one of nitrogen and argon, the temperature of the heating reaction is 600-1000° C., and the time is 3-8 hours; Preferably, in step S2, the mass ratio of the heteroatom-doped carbon support to the binder is 1:1 to 10:1, preferably 9:
1.
6. The preparation method according to claim 4, characterized in that: In step S3, the current collector is selected from one or more of stainless steel foil, aluminum foil, copper foil, and carbon paper; the coating thickness is 8 to 12 μm, preferably 10 μm; Preferably, in step S4, the electrodeposition process is specifically as follows: the current density is 0.5 to 1.5 mA cm -2 , electrodeposition time is 3 to 6 hours.
7. The preparation method according to claim 4, characterized in that: The positive electrode plate includes a positive electrode collector and a positive electrode material layer located on the surface of the positive electrode collector; the positive electrode collector is one or more of stainless steel foil, aluminum foil, copper foil, and carbon paper; the positive electrode active material included in the positive electrode material layer is selected from one or more of lithium iron phosphate, lithium cobalt oxide, ternary materials, and lithium-rich manganese-based positive electrode materials.
8. A lithium metal negative electrode, characterized in that The method comprises in-situ generating the nitrogen-rich solid electrolyte interface as described in any one of claims 1 to 2.
9. A lithium metal battery, characterized in that: The lithium metal battery generates the nitrogen-rich solid electrolyte interface according to any one of claims 1 to 2 in situ at its negative electrode during the charge and discharge cycle.
10. Use of the nitrogen-rich solid electrolyte interface according to any one of claims 1 to 2 in a lithium metal battery.