MOF negative electrode pre-lithiation method based on solid corrosion mechanism

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to an MOF negative electrode pre-lithiation method based on a solid-state corrosion mechanism. A metal lithium layer is deposited on the surface of MOF by adopting a vacuum thermal evaporation deposition process, a composite passivation protection layer composed of lithium carbonate (Li2CO3) and lithium oxide (Li2O) is generated in situ at an MOF / lithium interface through a solid corrosion reaction, and the protection layer can effectively protect nano metal particles (the particle size is 5 nm) generated by a lithiation reaction and inhibit dissolution and migration of the nano metal particles in the circulation process, so that the service life of the MOF / lithium battery is prolonged, and the service life of the MOF / lithium battery is prolonged. And the capacity retention ratio of the whole battery reaches 83.3% after 240 times of circulation under the 0.2 C multiplying power.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, and particularly relates to a MOF negative electrode prelithiation method based on a solid-state corrosion mechanism. BACKGROUND

[0002] It is imperative to develop advanced negative electrode materials for lithium ion batteries with longer cycle life and higher capacity to meet the escalating demands of portable electronic devices and electric vehicles. Commercial graphite negative electrodes are limited by their low theoretical capacity (372 mAh g -1 ), which does not meet the requirements of high-energy-density lithium ion batteries. In recent years, metal-organic framework materials (MOFs) have become promising candidates for next-generation lithium ion battery negative electrodes due to their tunable electrochemical performance and structural diversity. It is generally believed that the excellent electrochemical performance of MOFs is attributed to the metal nanoparticles generated during electrochemical cycling, which can provide electron transport channels and enhance electronic conductivity, thereby improving the overall electrochemical performance of MOF materials.

[0003] However, many studies have shown that the first-cycle coulombic efficiency (ICE) of MOFs rarely exceeds 80%, so prelithiation has been identified as a viable strategy to improve ICE and optimize the electrochemical performance of MOF negative electrode full cells. Electrochemical prelithiation has been widely used in previous work, and the main operating means is the direct contact of the electrode and lithium metal in the presence of a liquid electrolyte. However, full cells pairing the electrochemically prelithiated MOF negative electrode with commercial positive electrodes such as LiCoO2 (LCO) and LiFePO4 (LFP) still exhibit relatively low discharge capacity and energy density. Obviously, the full cell of the MOF negative electrode after electrochemical prelithiation still cannot compete with silicon-based full cells. Existing research has mainly focused on precise lithium supplement control, lithium utilization rate, formation of electrolyte decomposition byproducts, and corresponding electrochemical performance. However, the dissolution process of transition metal particles in the MOF negative electrode and the related electrochemical performance degradation mechanism are not clear. We attribute these degradation processes to the interaction of nanometer metal particles with the liquid electrolyte, and propose a contact-protective prelithiation strategy to inhibit the dissolution reaction of transition metals. SUMMARY

[0004] In view of the above, the purpose of the present application is to provide a MOF negative electrode prelithiation method based on a solid-state corrosion mechanism to provide a prelithiation method that not only reduces the expansion rate of the material and inhibits the dissolution reaction of transition metals, but also improves the cycle performance of the full cell.

[0005] In order to achieve the above purpose, the present application provides a MOF negative electrode prelithiation method based on a solid-state corrosion mechanism, comprising the following steps: prelithiating a MOF negative electrode in a vacuum degree ≤10 -2Pa, under the condition of operating environment dew point ≤-30℃, metal lithium is deposited on the surface of MOF negative electrode sheet by thermal evaporation deposition process to obtain pre-lithiated MOF negative electrode sheet.

[0006] Preferably, the metal lithium and the MOF undergo a solid-state coupling corrosion reaction, including a chemical corrosion reaction: a chemical lithiation process occurring when the metal lithium directly contacts the MOF; an electrochemical corrosion reaction: the metal lithium reacts with the CO2 and O2 molecules adsorbed on the surface of the MOF to generate a high ionic conductivity lithium carbonate and a lithium oxide ion conductor as an ion channel, and a conductive agent and newly generated nano metal particles Co / Ni as an electron channel, and an electrochemical lithiation reaction occurs under the driving of chemical potential.

[0007] Preferably, the preparation steps of the MOF negative electrode sheet are as follows: the MOF material, polyvinylidene fluoride, and conductive carbon are added to N-methyl pyrrolidone and stirred uniformly to obtain a negative electrode slurry; then the negative electrode slurry is coated on a negative electrode current collector copper foil, dried, and cut into a MOF negative electrode sheet with a diameter of 14mm.

[0008] Preferably, the weight ratio of the MOF material, polyvinylidene fluoride, conductive carbon, and N-methyl pyrrolidone is 70-80g:2-10g:2-10g:5-10g.

[0009] Preferably, the preparation steps of the MOF material are as follows: DMF and ethanol are mixed, then terephthalic acid is added and stirred uniformly to obtain a mixed solution; then nickel chloride hexahydrate and cobalt chloride hexahydrate are added to deionized water, and after completely dissolving, they are added to the mixed solution, and the obtained solution is transferred to an autoclave, heated at 150℃ for 24h, and the obtained product is suction filtered, washed with water, DMF and ethanol twice, and then dried at 70℃ overnight.

[0010] Preferably, the amount ratio of the DMF, ethanol, terephthalic acid, and deionized water is 20mL:20mL:1.2g:20mL; and the molar ratio of the nickel chloride hexahydrate and the cobalt chloride hexahydrate is 0-0.8:1.

[0011] Preferably, the evaporation temperature of the thermal evaporation deposition process is 300-800℃.

[0012] More preferably, the evaporation temperature of the thermal evaporation deposition process is 650-750℃.

[0013] Preferably, the purity of the metal lithium source is ≥99.9%.

[0014] Preferably, the deposition thickness is controlled by a crystal oscillator sheet, the thickness is 12-18μm, and the error is ≤5%.

[0015] Preferably, the application also provides a pre-lithiated MOF negative electrode sheet, which is prepared by the MOF negative electrode pre-lithiation method based on a solid-state corrosion mechanism.

[0016] Preferably, the pre-lithiated MOF negative electrode sheet can form a full battery together with a positive electrode, an electrolyte and a separator.

[0017] Preferably, the positive electrode is a lithium cobalt oxide (LiCoO2) material with a specific capacity ≥180 mAh / g.

[0018] Preferably, the electrolyte is 1M LiPF6 in EC:DMC:DEC = 1:1:1 (v:v:v).

[0019] Preferably, the separator is Celgard 2400.

[0020] Advantages of the application: In the present application, the MOF negative electrode material is pre-lithiated, and in this process, the CO2 and O2 molecules adsorbed in the MOFs react with the deposited lithium metal to form a Li2CO3 and Li2O protective layer, preventing the direct exposure of Co / Ni nanoparticles to the liquid electrolyte.

[0021] The full battery prepared from the pre-lithiated MOF material of the present application exhibits high energy density and excellent cycle performance, surpassing the performance of other MOF-based full batteries and being comparable to silicon-based full batteries, and the pre-lithiation stabilizes the Co / Ni nanoparticles through an inorganic protective layer rich in Li2CO3, Li2O and LiF, significantly reducing the dissolution of Co / Ni. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description,

[0023] Figure 1 XRD patterns of the MOF materials prepared in Examples 2, 5, 7 and Comparative Examples 1 and 2 of the present application;

[0024] Figure 2 Charge-discharge curves of the half battery test of the CoNi0.8-MOF negative electrode sheet prepared in Example 2 of the present application.

[0025] Figure 3 Half battery cycle performance test chart of the MOF materials prepared in Examples 2, 5, 7 and Comparative Example 1 of the present application.

[0026] Figure 4 Optical microscope picture of the solid-state corrosion lithium supplement process of Example 2 of the present application.

[0027] Figure 5Charge-discharge curves of MOF material obtained in Example 1, 2 and 3.

[0028] Figure 6 Cycle performance of full cell of MOF material obtained in Example 1, 2 and 3.

[0029] Figure 7 Comparison chart of Ni dissolution percentage after 200 cycles of full cell of MOF material obtained in Example 1, 2 and 3.

[0030] Figure 8 Performance test results of pre-lithiated electrode sheet obtained in Example 2 and Comparative Example 3, wherein a is the first cycle charge-discharge curve of the electrode sheet half-cell of solid-state corrosion pre-lithiation and liquid pre-lithiation, and b is the comparison column chart of the first efficiency and pre-lithiation efficiency of the above two electrode sheet half-cells.

[0031] Figure 9 Cycle performance of MOF material obtained in Example 2 and Comparative Example 3.

[0032] Figure 10 TEM chart of MOF material obtained in Example 2. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with specific examples.

[0034] Example 1: A pre-lithiated MOF negative electrode sheet (CoNi 0.8 -MOF) based on solid-state corrosion mechanism, the specific preparation steps are as follows:

[0035] (1) 20 mL of DMF and 20 mL of ethanol were added to a beaker, then 1.20 g of terephthalic acid was added, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; then cobalt chloride hexahydrate and nickel chloride hexahydrate were added to 20 mL of deionized water in a molar ratio of 1:0.8, and after complete dissolution, the above solution was mixed and magnetically stirred for 30 min, then the obtained solution was transferred to a 100 mL autoclave, heated at 150℃ for 24 h, then the powder gray product was obtained, the product was washed with water, DMF and ethanol twice, then dried in a vacuum oven at 70℃ overnight to obtain CoNi 0.8 -MOF material;

[0036] (2) 70 g of CoNi 0.8 -MOF material, 10 g of polyvinylidene fluoride, and 10 g of conductive carbon were added to 10 g of N-methyl pyrrolidone and stirred uniformly to obtain a negative electrode slurry; then the negative electrode slurry was coated on a negative electrode current collector copper foil, dried, and cut into a CoNi0.8 -MOF negative electrode;

[0037] (2) When the vacuum degree is ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, the metal lithium was deposited by thermal evaporation deposition process with the evaporation temperature controlled at 650℃. The rate of deposition on CoNi 0.8 -MOF negative electrode surface, the deposition thickness is 12μm, and the pre-lithiation CoNi 0.8 -MOF negative electrode.

[0038] Example 2: A pre-lithiated MOF negative electrode sheet (CoNi 0.8 -MOF), the specific preparation steps are as follows:

[0039] (1) 20 mL of DMF and 20 mL of ethanol were added to a beaker, followed by the addition of 1.20 g of terephthalic acid, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; cobalt chloride hexahydrate and nickel chloride hexahydrate were then added to 20 mL of deionized water at a molar ratio of 1:0.8. After complete dissolution, the above solutions were mixed and magnetically stirred for 30 min, and the resulting solution was transferred to a 100 mL autoclave and heated at 150 ° C for 24 h to obtain a powder-gray product. The product was washed twice with water, DMF, and ethanol, and then dried in a vacuum oven at 70 ° C overnight to obtain CoNi 0.8 -MOF materials;

[0040] (2) 76g CoNi 0.8 -MOF material, 7g polyvinylidene fluoride, and 7g conductive carbon were added to 8g N-methylpyrrolidone and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry was then coated on the negative electrode current collector copper foil, dried, and cut into CoNi 0.8 -MOF negative electrode;

[0041] (2) When the vacuum degree is ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, the metal lithium was deposited by thermal evaporation deposition process with the evaporation temperature controlled at 700℃. The rate of deposition on CoNi 0.8 -MOF negative electrode surface, the deposition thickness is 15μm, and the pre-lithiation CoNi 0.8 -MOF negative electrode.

[0042] Example 3: A pre-lithiated MOF negative electrode sheet (CoNi 0.8 -MOF), the specific preparation steps are as follows:

[0043] (1) 20 mL DMF and 20 ml ethanol were added into a beaker, then 1.20 g terephthalic acid was added, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; then cobalt chloride hexahydrate and nickel chloride hexahydrate were added to 20 mL of deionized water in a molar ratio of 1:0.8, and after complete dissolution, the above solution was mixed and magnetically stirred for 30 min, then the obtained solution was transferred into a 100 mL autoclave, and after heating at 150°C for 24 h, a powder gray product was obtained, which was washed with water, DMF and ethanol twice, and then dried in a vacuum oven at 70°C overnight to obtain CoNi 0.8 -MOF material;

[0044] (2) 80g CoNi 0.8 -MOF material, 2g polyvinylidene fluoride, 3g conductive carbon were added into 5g N-methyl pyrrolidone and stirred uniformly to obtain a negative electrode slurry; then the negative electrode slurry was coated on a negative electrode current collector copper foil, dried, and cut into a CoNi 0.8 -MOF negative electrode sheet with a diameter of 14mm;

[0045] (2) Under the conditions of vacuum degree ≤10 -2 Pa, operating environment dew point ≤-30°C, through a thermal evaporation deposition process, the evaporation temperature was controlled at 750°C, and lithium metal was deposited on the surface of the CoNi -MOF negative electrode sheet at a rate of 0.8 18μm, to obtain a pre-lithiated CoNi 0.8 -MOF negative electrode sheet.

[0046] Example 4: A pre-lithiated MOF negative electrode sheet (CoNi 0.4 -MOF) based on a solid-state corrosion mechanism, the specific preparation steps are as follows:

[0047] (1) 20 mL DMF and 20 ml ethanol were added into a beaker, then 1.20 g terephthalic acid was added, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; then cobalt chloride hexahydrate and nickel chloride hexahydrate were added to 20 mL of deionized water in a molar ratio of 1:0.4, and after complete dissolution, the above solution was mixed and magnetically stirred for 30 min, then the obtained solution was transferred into a 100 mL autoclave, and after heating at 150°C for 24 h, a powder gray product was obtained, which was washed with water, DMF and ethanol twice, and then dried in a vacuum oven at 70°C overnight to obtain CoNi 0.4 -MOF material;

[0048] (2) 70g CoNi 0.4The MOF material, 10 g of polyvinylidene fluoride, and 10 g of conductive carbon are added to 10 g of N-methylpyrrolidone and stirred to obtain a negative electrode slurry. Then the negative electrode slurry is coated on a negative electrode current collector copper foil, and after drying, the CoNi 0.4 -MOF negative electrode sheet is cut into a diameter of 14 mm.

[0049] (2) Under the conditions of a vacuum degree ≤10 -2 Pa and an operating environment dew point ≤-30℃, a metal lithium is deposited on the surface of the CoNi -MOF negative electrode sheet at a rate of 1.5 μm / min by a thermal evaporation deposition process with an evaporation temperature of 650℃, and a deposition thickness of 12 μm, to obtain a pre-lithiated CoNi 0.4 -MOF negative electrode sheet. 0.4

[0050] Example 5: A pre-lithiated MOF negative electrode sheet (CoNi 0.4 -MOF) based on a solid-state corrosion mechanism, and the specific preparation steps are as follows:

[0051] (1) 20 mL of DMF and 20 mL of ethanol are added to a beaker, and then 1.20 g of terephthalic acid is added. The solution is magnetically stirred until the terephthalic acid is completely dispersed. Then, cobalt chloride hexahydrate and nickel chloride hexahydrate are added to 20 mL of deionized water in a molar ratio of 1:0.4. After complete dissolution, the above solutions are mixed and magnetically stirred for 30 min. Then, the obtained solution is transferred to a 100 mL autoclave. After heating at 150℃ for 24 h, a powder gray product is obtained. The product is washed with water, DMF and ethanol twice, and then dried in a vacuum oven at 70℃ overnight to obtain a CoNi 0.4 -MOF material.

[0052] (2) 76 g of the CoNi 0.4 -MOF material, 7 g of polyvinylidene fluoride, and 7 g of conductive carbon are added to 8 g of N-methylpyrrolidone and stirred to obtain a negative electrode slurry. Then the negative electrode slurry is coated on a negative electrode current collector copper foil, and after drying, the CoNi 0.4 -MOF negative electrode sheet is cut into a diameter of 14 mm.

[0053] (2) Under the conditions of a vacuum degree ≤10 -2 Pa and an operating environment dew point ≤-30℃, a metal lithium is deposited on the surface of the CoNi -MOF negative electrode sheet at a rate of 1.5 μm / min by a thermal evaporation deposition process with an evaporation temperature of 700℃, and a deposition thickness of 15 μm, to obtain a pre-lithiated CoNi 0.4 -MOF negative electrode sheet. 0.4

[0054] ​​Example 6: A pre-lithiated MOF anode electrode sheet (CoNi 0.4 -MOF) based on solid-state corrosion mechanism, the specific preparation steps are as follows:

[0055] (1) Add 20 mL of DMF and 20 mL of ethanol to a beaker, then add 1.20 g of terephthalic acid, and magnetically stir the solution until the terephthalic acid is completely dispersed; then add cobalt chloride hexahydrate and nickel chloride hexahydrate in a molar ratio of 1:0.4 to 20 mL of deionized water, completely dissolve, then mix the above solutions and magnetically stir for 30 min, then transfer the resulting solution to a 100 mL autoclave, heat at 150°C for 24 h, then wash the product with water, DMF and ethanol twice, then dry in a vacuum oven at 70°C overnight to obtain a CoNi 0.4 -MOF material;

[0056] (2) Add 80 g of CoNi 0.4 -MOF material, 2 g of polyvinylidene fluoride, and 3 g of conductive carbon to 5 g of N-methyl pyrrolidone and stir until uniform to obtain an anode slurry; then coat the anode slurry on a copper foil anode current collector, dry, and cut into CoNi 0.4 -MOF anode electrode sheets with a diameter of 14 mm;

[0057] (2) Under the conditions of a vacuum degree ≤10 -2 Pa and an operating environment dew point ≤-30°C, deposit metal lithium on the surface of the CoNi -MOF anode electrode sheet at a rate of 1.0 μm / min by a thermal evaporation deposition process with an evaporation temperature of 750°C to obtain a pre-lithiated CoNi 0.4 -MOF anode electrode sheet with a deposition thickness of 18 μm. 0.4

[0058] Example 7: A pre-lithiated MOF anode electrode sheet (Co-MOF) based on a solid-state corrosion mechanism, the specific preparation steps are as follows:

[0059] (1) Add 20 mL of DMF and 20 mL of ethanol to a beaker, then add 1.20 g of terephthalic acid, and magnetically stir the solution until the terephthalic acid is completely dispersed; then add 2.38 g of cobalt chloride hexahydrate to 20 mL of deionized water, completely dissolve, then mix the above solutions and magnetically stir for 30 min, then transfer the resulting solution to a 100 mL autoclave, heat at 150°C for 24 h, then wash the product with water, DMF and ethanol twice, then dry in a vacuum oven at 70°C overnight to obtain a Co-MOF material;

[0060] ​(2) 70 g of Co-MOF material, 10 g of polyvinylidene fluoride, and 10 g of conductive carbon were added to 10 g of N-methylpyrrolidone and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry was then coated on the negative electrode current collector copper foil, dried, and cut into Co-MOF negative electrode sheets with a diameter of 14 mm;

[0061] (2) When the vacuum degree is ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, the metal lithium was deposited by thermal evaporation deposition process with the evaporation temperature controlled at 650℃. The material was deposited on the surface of the Co-MOF negative electrode sheet at a rate of 12 μm, and the deposition thickness was 12 μm, thereby obtaining a pre-lithiated Co-MOF negative electrode sheet.

[0062] Example 8: A pre-lithiated MOF negative electrode sheet (Co-MOF) based on a solid-state corrosion mechanism, the specific preparation steps are as follows:

[0063] (1) 20 mL of DMF and 20 mL of ethanol were added to a beaker, followed by the addition of 1.20 g of terephthalic acid, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; 2.38 g of cobalt chloride hexahydrate was then added to 20 mL of deionized water. After complete dissolution, the above solutions were mixed and magnetically stirred for 30 min, and the resulting solution was transferred to a 100 mL autoclave and heated at 150 ° C for 24 h to obtain a pink-gray product. The product was washed twice with water, DMF, and ethanol, and then dried in a vacuum oven at 70 ° C overnight to obtain a Co-MOF material;

[0064] (2) 76 g of Co-MOF material, 7 g of polyvinylidene fluoride, and 7 g of conductive carbon were added to 8 g of N-methylpyrrolidone and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry was then coated on the negative electrode current collector copper foil, dried, and cut into Co-MOF negative electrode sheets with a diameter of 14 mm;

[0065] (2) When the vacuum degree is ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, the metal lithium was deposited by thermal evaporation deposition process with the evaporation temperature controlled at 700℃. The material was deposited on the surface of the Co-MOF negative electrode sheet at a rate of 15 μm, and the deposition thickness was 15 μm, thereby obtaining a pre-lithiated Co-MOF negative electrode sheet.

[0066] Example 9: A pre-lithiated MOF negative electrode sheet (Co-MOF) based on a solid-state corrosion mechanism, the specific preparation steps are as follows:

[0067] (1) 20 mL of DMF and 20 mL of ethanol were added into a beaker, then 1.20 g of terephthalic acid was added, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; then 2.38 g of cobalt chloride hexahydrate was added into 20 mL of deionized water, and after complete dissolution, the above solutions were mixed and magnetically stirred for 30 min, then the obtained solution was transferred into a 100 mL autoclave, after heating at 150 °C for 24 h, a powder gray product was obtained, the product was washed twice with water, DMF and ethanol, and then dried in a vacuum oven at 70 °C overnight to obtain a Co-MOF material;

[0068] (2) 80 g of the Co-MOF material, 2 g of polyvinylidene fluoride and 3 g of conductive carbon were added into 5 g of N-methylpyrrolidone and stirred uniformly to obtain a negative electrode slurry; then the negative electrode slurry was coated on a negative electrode current collector copper foil, dried, and cut into a Co-MOF negative electrode sheet with a diameter of 14 mm;

[0069] (2) Under the conditions of a vacuum degree ≤10 -2 Pa, and an operating environment dew point ≤-30 °C, a metal lithium was deposited on the surface of the Co-MOF negative electrode sheet at a rate of 18 μm by a thermal evaporation deposition process with an evaporation temperature of 750 °C to obtain a pre-lithiated Co-MOF negative electrode sheet.

[0070] Comparative Example 1: The difference from Example 2 is that the negative electrode material is Li2BDC;

[0071] (1) 20 mL of DMF and 20 mL of ethanol were added into a beaker, then 1.20 g of terephthalic acid was added, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; then lithium chloride monohydrate was added into 20 mL of deionized water, and after complete dissolution, the above solutions were mixed and magnetically stirred for 30 min, then the obtained solution was transferred into a 100 mL autoclave, after heating at 150 °C for 24 h, a powder gray product was obtained, the product was washed twice with water, DMF and ethanol, and then dried in a vacuum oven at 70 °C overnight to obtain a Li2BDC material;

[0072] (2) 76 g of the Li2BDC material, 7 g of polyvinylidene fluoride and 7 g of conductive carbon were added into 8 g of N-methylpyrrolidone and stirred uniformly to obtain a negative electrode slurry; then the negative electrode slurry was coated on a negative electrode current collector copper foil, dried, and cut into a Li2BDC negative electrode sheet with a diameter of 14 mm;

[0073] (2) Under the conditions of a vacuum degree ≤10 -2 Pa, and an operating environment dew point ≤-30 °C, a metal lithium was deposited on the surface of the Co-MOF negative electrode sheet at a rate of The lithiation was deposited on the surface of the Li2BDC negative electrode sheet at a rate of 15 μm, and the deposition thickness was 15 μm, thereby obtaining a pre-lithiated Li2BDC negative electrode sheet.

[0074] Comparative Example 2: The difference from Example 2 is that the negative electrode material is MOF CCDC:985792.

[0075] Comparative Example 3: The difference from Example 2 is that liquid corrosion pre-lithiation, the specific steps are as follows:

[0076] (1) 20 mL of DMF and 20 mL of ethanol were added to a beaker, followed by the addition of 1.20 g of terephthalic acid, and the solution was magnetically stirred until the terephthalic acid was completely dispersed; cobalt chloride hexahydrate and nickel chloride hexahydrate were then added to 20 mL of deionized water at a molar ratio of 1:0.8. After complete dissolution, the above solutions were mixed and magnetically stirred for 30 min, and the resulting solution was transferred to a 100 mL autoclave and heated at 150 ° C for 24 h to obtain a powder-gray product. The product was washed twice with water, DMF, and ethanol, and then dried in a vacuum oven at 70 ° C overnight to obtain CoNi 0.8 -MOF materials;

[0077] (2) 76g CoNi 0.8 -MOF material, 7g polyvinylidene fluoride, and 7g conductive carbon were added to 8g N-methylpyrrolidone and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry was then coated on the negative electrode current collector copper foil, dried, and cut into CoNi 0.8 -MOF negative electrode;

[0078] (2) When the vacuum degree is ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, the metal lithium was deposited by thermal evaporation deposition process with the evaporation temperature controlled at 700℃. The rate of deposition on CoNi 0.8 -MOF negative electrode surface, the deposition thickness is 15μm, and the pre-lithiation CoNi 0.8 -MOF negative electrode sheet, and then pre-lithiated CoNi 0.8 -MOF negative electrode piece was quickly immersed in electrolyte in the glove box atmosphere to obtain liquid corrosion pre-lithiation CoNi 0.8 -MOF negative electrode.

[0079] Performance Testing

[0080] Positive electrode sheet preparation: Lithium cobalt oxide, binder polyvinylidene fluoride, and conductive carbon are added to N-methylpyrrolidone in the required weight ratio of 94:3:3, stirred and homogenized to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector aluminum foil, and the positive electrode sheet is obtained after drying and cutting;

[0081] Electrochemical testing: The half-cells and full-cells for the tests were assembled in CR-2032 coin cells in an argon-filled glove box (H2O <1ppm, O2 <1ppm), where 100 μL of 1M LiPF6, EC:DMC:DEC (volume = 1:1:1) was used as the electrolyte and Celgard 2400 was used as the separator. The half-cells (1C = 1000 mA g) were tested at room temperature using a Neware battery test system (Neware Technology Limited, China) in the range of 0.01–3.0 V vs. Li / Li+. -1 ) and 4.45-1V for full battery (1C=180mAg -1 ).

[0082] Cyclic voltammetry (CV) tests were performed on a CHI660e workstation (Shanghai Chenhua Company) with a scan rate of 0.2 mVs. -1 , the range is 0-3.0V;

[0083] Electrochemical impedance spectroscopy (EIS) was performed on a CHI660e workstation (Shanghai Chenhua Company) with a frequency range of 10 -5 -10 - 2 Hz.

[0084] Data Analysis: This study synthesized MOF materials and treated them via a solid-state corrosion pre-lithiation strategy, demonstrating their feasibility as lithium-ion battery anode materials to compensate for the significant lithium loss in MOF anodes. A comprehensive characterization of the pre-lithiation process demonstrated the feasibility of solid-state corrosion for MOF materials.

[0085] During the solid-state corrosion pre-lithiation process, the CO2 and O2 molecules adsorbed in the MOF react with the deposited lithium metal to form Li2CO3 and Li2O protective layers, preventing the Co / Ni nanoparticles from being directly exposed to the liquid electrolyte. The full battery using solid-state corrosion pre-lithiation MOF showed a high energy density (493Wh kg -1 ) and excellent cycling performance (83.3% capacity retention after 240 cycles at 0.2C), surpassing the performance of other MOF full batteries and comparable to that of silicon-based full batteries.

[0086] The content of dissolved products in the electrolyte was analyzed by ICP. Solid-state corrosion pre-lithiation stabilized the Co / Ni nanoparticles through an inorganic protective layer rich in Li2CO3, Li2O, and LiF, significantly reducing Co / Ni dissolution. This invention provides a new perspective for understanding the electrochemical degradation mechanism of MOFs and points out that the solid-state corrosion pre-lithiation strategy is a core technology for unlocking the potential of MOFs materials in high-energy-density lithium-ion batteries.

[0087] It should be understood by those of ordinary skill in the art that the discussion of any embodiment is merely exemplary and is not intended to limit the scope of the application; the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the application as described above, which are not provided in details for the sake of brevity.

Claims

1. A MOF negative electrode pre-lithiation method based on solid-state corrosion mechanism, characterized in that: The following steps are involved: At vacuum degree ≤10 -2 Under the conditions of Pa and operating environment dew point ≤-30℃, metallic lithium is deposited on the surface of the MOF negative electrode piece by a thermal evaporation deposition process to obtain a pre-lithiated MOF negative electrode piece.

2. The MOF negative electrode pre-lithiation method based on the solid-state corrosion mechanism according to claim 1, characterized in that: The preparation steps of the MOF negative electrode sheet are as follows: MOF material, polyvinylidene fluoride, and conductive carbon are added to N-methylpyrrolidone and stirred evenly to obtain a negative electrode slurry; the negative electrode slurry is then coated on the negative electrode current collector copper foil, dried, and cut into MOF negative electrode sheets with a diameter of 14 mm.

3. The MOF negative electrode pre-lithiation method based on the solid-state corrosion mechanism according to claim 2, characterized in that: The weight ratio of the MOF material, polyvinylidene fluoride, conductive carbon and N-methylpyrrolidone is 70-80g:2-10g:2-10g:5-10g.

4. The MOF negative electrode pre-lithiation method based on the solid-state corrosion mechanism according to claim 1, characterized in that: The preparation steps of the MOF material are as follows: DMF and ethanol are mixed, and then terephthalic acid is added and stirred evenly to obtain a mixed solution; nickel chloride hexahydrate and cobalt chloride hexahydrate are then added to deionized water, and after they are completely dissolved, they are added to the mixed solution, and the resulting solution is transferred to an autoclave and heated at 150°C for 24 hours. The resulting product is filtered, washed twice with water, DMF and ethanol, and then dried at 70°C overnight.

5. The MOF negative electrode pre-lithiation method based on solid-state corrosion mechanism according to claim 4, characterized in that: The usage ratio of DMF, ethanol, terephthalic acid and deionized water is 20 mL:20 mL:1.2 g:20 mL; and the molar ratio of nickel chloride hexahydrate to cobalt chloride hexahydrate is 0-0.8:

1.

6. The MOF negative electrode pre-lithiation method based on solid-state corrosion mechanism according to claim 1, characterized in that: The evaporation temperature of the thermal evaporation deposition process is 300-800°C.

7. The MOF negative electrode pre-lithiation method based on solid-state corrosion mechanism according to claim 1, characterized in that: The deposition thickness is 12-18 μm.

8. A pre-lithiated MOF negative electrode plate, characterized in that: It is prepared by the MOF negative electrode pre-lithiation method based on the solid-state corrosion mechanism according to any one of claims 1-7.

9. The pre-lithiated MOF negative electrode according to claim 8, characterized in that: The pre-lithiated MOF negative electrode sheet can be combined with a positive electrode, an electrolyte and a separator to form a full battery.

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