An electrode gas absorption enrichment material, a preparation method thereof and a lump-free lithium battery

Abstract

This invention discloses a gas absorption and enrichment material for battery cells, its preparation method, and an anti-bulging lithium battery. The material consists of a conductive support framework, a gradient adsorption layer coated on the surface of the conductive support framework, and a catalytic conversion layer deposited on the surface of the gradient adsorption layer. It is prepared after pre-expansion treatment and encapsulation with a breathable membrane. The conductive support framework is a boron-doped graphene aerogel with a Li3PO4 nanolayer deposited on its surface. The gradient adsorption layer includes a primary adsorption layer and a secondary adsorption layer. The primary adsorption layer uses ZIF-8@activated carbon core-shell slurry, and the secondary adsorption layer uses an amino-modified MIL-101(Cr) slurry. The catalytic conversion layer is a MnO2-Ni3N heterojunction nanoarray with an ALD porous protective film deposited on its surface. This invention solves the problems of low overall absorption rate, significant volume expansion after adsorption, and poor electrochemical safety in existing carbon-based porous materials when adsorbing complex battery cell gases.

Description

Technical Field

[0001] This invention relates to the field of battery cells, specifically to a cell gas absorption and enrichment material, its preparation method, and an anti-bulging lithium battery. Background Technology

[0002] Gas generation in battery cells during charge-discharge cycles and use is a common phenomenon, occurring under both normal operating conditions and extreme conditions such as high temperatures. For example, during normal use, electrolyte redox decomposition occurs. In the high-potential region of the positive electrode, electrolyte solvent molecules lose electrons and are oxidized, generating gases such as CO2 and CO. In the low-potential region of the negative electrode, solvent molecules gain electrons and are reduced, generating alkanes (such as CH4 and C2H6) and alkenes (such as C2H4). This process is directly related to the battery's charge-discharge state and continues to occur during normal cycling, making it an unavoidable side reaction. Additionally, the solid electrolyte interphase (SEI) film forms during the battery's first charge-discharge (formation), a process that generates gases such as CO, CO2, and C2H4. As the battery cycles, the SEI film continuously ruptures and repairs, with each repair process accompanied by new gas-generating reactions. This gas-generating mechanism persists throughout the battery's lifespan, becoming particularly pronounced under high-temperature environments. Under high temperature or extreme conditions, the SEI film will undergo thermal decomposition. That is, when the temperature exceeds 80-120℃, unstable components in the SEI film (such as ROCO2Li) begin to decompose, releasing gases such as CO2 and accompanied by exothermic reactions, which may further accelerate the thermal runaway process. In addition, the binders commonly used in the negative electrode, such as PVDF and CMC, will decompose to produce H2 at high temperature or high reduction potential. At the same time, the high-nickel ternary cathode (such as NCM811 and NCA) has an unstable crystal structure under high temperature (greater than 180℃) and deep delithiation state, which will release active oxygen (O2). These active oxygens will further react with the electrolyte to produce a large amount of CO and CO2 gas, while releasing a large amount of heat.

[0003] In summary, the gaseous composition generated during thermal runaway of lithium-ion batteries is complex, but mainly consists of CO2 (35-50%), CO (25-35%), H2 (15-25%), C2H4 (5-10%), and CH4 (3-8%), accounting for over 99% of the total gas content. When the generated gases cannot be expelled in time, they can trigger a series of chain reactions within the battery and at the system level. The most common hazard is battery swelling and bulging, which can lead to casing rupture and electrolyte leakage, and even flammable gas explosions and thermal runaway chain reactions.

[0004] Currently, the industry has developed a multi-layered approach to address battery gas generation, forming a comprehensive prevention and control system from source suppression to process control and end-of-pipe protection. Firstly, pressure relief and venting technologies are used, including mechanical pressure relief valves, active venting systems, and thermal runaway-oriented diversion. Secondly, environmental control is strengthened, including intelligent charging management, intelligent temperature regulation, and over-discharge protection. Thirdly, the materials and designs of electrolytes and electrodes can be optimized. For example, patent CN118160141A discloses a cell venting channel, a battery device, and a method for venting gas from a battery, which can effectively and safely remove harmful gases from the battery. However, this type of guided venting method has the following drawbacks: it only vents high-temperature flammable gases from the battery system, without addressing the flammability / toxicity of the gases. Gases vented outside the vehicle may still accumulate to explosive limits in enclosed spaces (such as garages), or spontaneously combust upon contact with air, or threaten personnel safety. If the venting is connected to a collection device, the collection device, along with the existing chambers and diversion channels, will increase the volume and reduce the battery pack's energy density.

[0005] Therefore, direct adsorption can be used to absorb the gas directly inside the battery cell, avoiding or reducing emissions. For example, patent document CN110050375A, filed by Kurita Industrial Co., Ltd., discloses a carbon-based porous material that can be used to absorb methane gas generated during lithium-ion battery malfunctions. Another example is patent document CN117477049A, filed by Beijing Xibei Power Technology Co., Ltd., which discloses a battery and its containing cell that absorb and channel gas, also using a conductive porous carbon material for cell gas adsorption. However, these carbon-based porous materials are not suitable for complex cell gases with multiple components, have low overall absorption rates, and suffer from significant volume expansion after adsorption, as well as poor electrochemical safety. Summary of the Invention

[0006] The purpose of this invention is to provide a cell gas absorption and enrichment material, its preparation method, and an anti-bulging lithium battery, which solves the problems of low overall absorption rate, significant volume expansion after adsorption, and poor electrochemical safety of existing carbon-based porous materials when adsorbing complex cell gases.

[0007] The present invention achieves the above objectives through the following technical solutions:

[0008] A cell gas absorption and enrichment material is provided, the material being composed of a conductive support skeleton, a gradient adsorption layer coated on the surface of the conductive support skeleton, and a catalytic conversion layer deposited on the surface of the gradient adsorption layer, and is prepared after pre-expansion treatment and gas-permeable membrane encapsulation.

[0009] The conductive support framework is a boron-doped graphene aerogel with a Li3PO4 nanolayer deposited on its surface.

[0010] The gradient adsorption layer includes a primary adsorption layer and a secondary adsorption layer coated sequentially from the inside out. The primary adsorption layer uses ZIF-8@activated carbon core-shell slurry, and the secondary adsorption layer uses amino-modified MIL-101(Cr) slurry.

[0011] The catalytic conversion layer is a MnO2-Ni3N heterojunction nanoarray with an ALD porous protective film deposited on its surface.

[0012] The present invention also provides a method for preparing the aforementioned cell gas absorption and enrichment material, the method comprising the following steps:

[0013] S1. Boric acid and graphene oxide dispersion are ultrasonically mixed, hydrothermally reduced and freeze-dried in sequence to obtain boron-doped graphene aerogel. Then, LiOH and H3PO4 are added to ethanol solution as solvent and reacted to obtain Li3PO4 precursor solution. The Li3PO4 precursor solution is deposited on the surface of boron-doped graphene aerogel by dip-coating method to obtain conductive support framework.

[0014] S2. Prepare ZIF-8@ activated carbon core-shell particles, add them to N-methylpyrrolidone, add additives, and mix to obtain ZIF-8@ activated carbon core-shell slurry; then take Cr(NO3)3·9H2O, terephthalic acid and 2-aminoterephthalic acid, mix them, and synthesize them by hydrothermal treatment to obtain amino-modified MIL-101(Cr), add it to N-methylpyrrolidone, add additives, and mix to obtain amino-modified MIL-101(Cr) slurry;

[0015] S3. ZIF-8@activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton, and then vacuum dried and hot-pressed to obtain a gradient adsorption layer.

[0016] S4. A mixed aqueous solution of MnSO4 and Na2SO4 was used as the electrodeposition solution to electrodeposit MnO2 nanowire array on the surface of the gradient adsorption layer. The array was then immersed in NiCl2 solution, removed and purged with nitrogen gas. After nitriding treatment, MnO2-Ni3N heterojunction nanoarray was obtained. Finally, ALD porous protective film was deposited on the surface of the array using trimethylaluminum and deionized water as alternating precursors to obtain the catalytic conversion layer.

[0017] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation to obtain the cell gas absorption and enrichment material.

[0018] A further improvement is that, in step S1, the mass concentration of the graphene oxide dispersion is 2-2.5%, the ratio of boric acid to graphene oxide dispersion is 0.5g:450-550mL, the ultrasonic mixing frequency is 35-45kHz, the time is 1-1.2h, the hydrothermal reduction temperature is 170-180℃, the time is 5-8h, the freeze-drying temperature is -40 to -50℃, the time is 36-48h, the mass concentration of the ethanol solution is 65-75%, the added concentration of LiOH is 0.08-0.12M, and the added concentration of H3PO4 is 0.025-0.035M.

[0019] The dipping and pulling method has a pulling speed of 10-12 mm / min, and after the pulling is completed, it is sintered at 295-305℃ for 1-1.2 h under nitrogen protection.

[0020] A further improvement is that, in step S2, the specific operation for preparing ZIF-8@ activated carbon core-shell particles is as follows: Take activated carbon and wash it until neutral after reflux with concentrated nitric acid, then take Zn(NO3)2·6H2O and 2-methylimidazole and dissolve them in methanol to obtain a coating solution, add activated carbon to the coating solution, stir at room temperature for 24-32 hours, and then centrifuge to collect ZIF-8@ activated carbon core-shell particles;

[0021] The reflux temperature of the concentrated nitric acid is 80-85℃, and the time is 2.5-3.5h. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole and methanol is 5.95g:6.5g:500-550mL. The ratio of activated carbon to coating solution is 10g:400-600mL.

[0022] A further improvement is that, in step S2, the mass ratio of Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid is 1:0.4:0.1, and the hydrothermal synthesis refers to reacting at 145-155℃ for 10-14h, followed by methanol Soxhlet extraction for 36-48h, and finally vacuum activation at 145-155℃.

[0023] A further improvement is that, in step S2, the additives in the ZIF-8@ activated carbon core-shell slurry include polyvinylidene fluoride-hexafluoropropylene copolymer, lithium bis(trifluoromethanesulfonyl)imide, hydrophobic SiO2 nanospheres, and multi-walled carbon nanotubes, and the mass percentages of each component are as follows: ZIF-8@ activated carbon core-shell particles 42-48%, polyvinylidene fluoride-hexafluoropropylene copolymer 10-15%, lithium bis(trifluoromethanesulfonyl)imide 2-4%, hydrophobic SiO2 nanospheres 2-4%, multi-walled carbon nanotubes 1-3%, and N-methylpyrrolidone 32-38%.

[0024] The additives in the amino-modified MIL-101(Cr) slurry include polyvinylidene fluoride-hexafluoropropylene copolymer, lithium bis(trifluoromethanesulfonyl)imide, and carbon black, and the mass percentages of each component are as follows: amino-modified MIL-101(Cr) 32-38%, polyvinylidene fluoride-hexafluoropropylene copolymer 12-18%, lithium bis(trifluoromethanesulfonyl)imide 2-5%, carbon black 1-2%, and N-methylpyrrolidone 40-50%.

[0025] A further improvement is that, in step S3, the wet film thickness of the ZIF-8@ activated carbon core-shell slurry coating is 90-110 μm, the wet film thickness of the amino-modified MIL-101(Cr) slurry coating is 70-80 μm, the vacuum drying temperature is 70-80℃, the time is 1.8-2.2 h, and the hot pressing temperature is 110-120℃, the pressure is 8-12 MPa, and the time is 4-6 min.

[0026] A further improvement is that, in step S4, the concentrations of MnSO4 and Na2SO4 are both 0.08-0.12M, the electrodeposition voltage is 0.8V vs. Ag / AgCl, the time is 20±2min, and the temperature is 25±1℃.

[0027] The concentration of the NiCl2 solution is 0.04-0.06M, the immersion time is 4-6 min, and the nitriding treatment refers to the reaction at 398-402℃ in an NH3 atmosphere for 0.8-1.2 h.

[0028] The atomic layer deposition temperature was 120±2℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01nm / cycle.

[0029] A further improvement is that, in step S5, the pre-expansion treatment refers to placing the product in a high-pressure autoclave, filling it with N2 to 0.5±0.02MPa and maintaining the pressure for 1-1.2h, and then depressurizing it to atmospheric pressure at a rate of 0.02-0.04MPa / min. The permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 45-55μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 140-150℃, the pressure is 0.4-0.6MPa, and the time is 8-10s.

[0030] The present invention also provides an anti-bulging lithium battery, wherein the cell of the anti-bulging lithium battery includes a positive current collector, a positive coating, a separator, a negative coating, a negative current collector and an electrolyte arranged in sequence, and the top sealing area of ​​the cell is provided with the cell gas absorption and enrichment material.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) This invention achieves synergistic treatment of battery cell gases through catalytic conversion and gradient adsorption, and ultimately achieves efficient adsorption and fixation. It can be used for gas adsorption and enrichment under normal battery operating conditions (non-thermal runaway), avoiding or significantly reducing gas escape. Among them, the MnO2-Ni3N heterojunction nanoarray structure converts CO / H2 into inert CO2 / NH3, the ZIF-8@activated carbon core-shell structure can efficiently capture CO2 and C2H4, and the amino-modified MIL-101(Cr) structure can fix CO and CH4 through coordination, while also being able to adsorb NH3 a second time.

[0033] (2) The present invention uses boron-doped graphene aerogel as a conductive support framework to provide mechanical support and electronic conduction path, and reserves gas diffusion channel. It also has a certain elastic modulus to resist adsorption stress. At the same time, after pre-expansion treatment, the overall volume expansion rate of the material can be significantly reduced.

[0034] (3) The present invention can block electrolyte penetration by depositing Li3PO4 nanolayer on the surface of conductive support framework. At the same time, an ALD porous protective film is deposited on the surface of MnO2-Ni3N heterojunction nanoarray using atomic layer deposition technology. The grain boundary channel does not affect the adsorption effect and can also prevent metal dissolution and contamination of electrolyte, reduce electrochemical interference, and maintain the catalytic mechanism. In addition, the use of Ni3N catalysis can avoid the use of precious metals and prevent short circuit caused by reduced metals, resulting in high safety and stability. Detailed Implementation

[0035] The present application will be further described in detail below with reference to specific embodiments. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0036] I. Conducting the Experiment

[0037] Unless otherwise specified, all raw materials used in this experiment are ordinary commercially available materials.

[0038] Example 1

[0039] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0040] S1. Boric acid and a 2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (35 kHz, 1.2 h), hydrothermal reduction (170 °C, 8 h), and freeze-drying (-40 °C, 48 h) to obtain boron-doped graphene aerogel. Then, using a 65% (w / w) ethanol solution as a solvent, 0.08 M LiOH and 0.025 M H3PO4 were added and reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 10 mm / min. After dip-coating, the aerogel was sintered at 295 °C for 1.2 h under nitrogen protection to obtain a conductive support framework.

[0041] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 24 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 80℃, and the time is 3.5 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:500mL, and the ratio of activated carbon to coating solution is 10g:400mL.

[0042] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 42% ZIF-8@ activated carbon core-shell particles, 10% polyvinylidene fluoride-hexafluoropropylene copolymer, 4% lithium bis(trifluoromethanesulfonylimide), 4% hydrophobic SiO2 nanospheres, 3% multi-walled carbon nanotubes, and 37% N-methylpyrrolidone.

[0043] Then, Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and hydrothermally synthesized (first reacted at 145℃ for 14h, then extracted with methanol by Soxhlet for 36h, and finally activated under vacuum at 145℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 32% amino-modified MIL-101(Cr), 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 5% lithium bis(trifluoromethanesulfonylimide), 2% carbon black, and 49% N-methylpyrrolidone.

[0044] S3. ZIF-8@activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@activated carbon core-shell slurry is 90 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 70 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 70℃ and the time is 2.2 h. The hot-pressing temperature is 110℃, the pressure is 8 MPa, and the time is 6 min, finally obtaining a gradient adsorption layer.

[0045] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.08M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 18 min, and the temperature was 26℃. The arrays were then immersed in a 0.04M NiCl2 solution for 6 min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reaction at 398℃ for 1.2 h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 118℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01 nm / cycle, resulting in a catalytic conversion layer.

[0046] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.48 MPa and holding it at that pressure for 1.2 hours, and then depressurizing it to atmospheric pressure at a rate of 0.02 MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 45 μm and a pore size of 0.2 ± 0.02 μm. The hot-pressing temperature is 140℃, the pressure is 0.4 MPa, and the time is 10 seconds, thus obtaining the cell gas absorption and enrichment material.

[0047] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0048] Example 2

[0049] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0050] S1. Boric acid and a 2.2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (40 kHz, 1.1 h), hydrothermal reduction (175 °C, 6 h), and freeze-drying (-45 °C, 42 h) to obtain boron-doped graphene aerogel. A 70% (w / w) ethanol solution was then used as a solvent to add 0.1 M LiOH and 0.03 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 11 mm / min. After dip-coating, the aerogel was sintered at 300 °C for 1.1 h under nitrogen protection to obtain a conductive support framework.

[0051] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0052] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0053] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0054] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2h. The hot-pressing temperature is 115℃, the pressure is 10MPa, and the time is 5min, finally obtaining a gradient adsorption layer.

[0055] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.1M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 20 min, and the temperature was 25℃. The arrays were then immersed in a 0.05M NiCl2 solution for 5 min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reacting at 400℃ for 1 h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 120℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01 nm / cycle, resulting in a catalytic conversion layer.

[0056] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.5MPa and holding it at that pressure for 1.1 hours, and then depressurizing it to atmospheric pressure at a rate of 0.03MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 145℃, the pressure is 0.5MPa, and the time is 9s, thus obtaining the cell gas absorption and enrichment material.

[0057] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0058] Example 3

[0059] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0060] S1. Boric acid and a 2.5% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (45 kHz, 1 h), hydrothermal reduction (180 °C, 5 h), and freeze-drying (-50 °C, 36 h) to obtain boron-doped graphene aerogel. A 75% (w / w) ethanol solution was then used as a solvent to add 0.12 M LiOH and 0.035 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 12 mm / min. After dip-coating, the aerogel was sintered at 305 °C for 1 h under nitrogen protection to obtain a conductive support framework.

[0061] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 32 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 85℃, and the time is 2.5 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:550mL, and the ratio of activated carbon to coating solution is 10g:600mL.

[0062] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 48% ZIF-8@ activated carbon core-shell particles, 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 2% lithium bis(trifluoromethanesulfonylimide), 2% hydrophobic SiO2 nanospheres, 1% multi-walled carbon nanotubes, and 32% N-methylpyrrolidone.

[0063] Then, Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and hydrothermally synthesized (first reacted at 155℃ for 10h, then extracted with methanol by Soxhlet for 48h, and finally activated under vacuum at 155℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 38% amino-modified MIL-101(Cr), 18% polyvinylidene fluoride-hexafluoropropylene copolymer, 2% lithium bis(trifluoromethanesulfonylimide), 1% carbon black, and 41% N-methylpyrrolidone.

[0064] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 110 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 80 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 80℃ and the time is 1.8h. The hot-pressing temperature is 120℃, the pressure is 12MPa, and the time is 4min, finally obtaining a gradient adsorption layer.

[0065] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.12M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 22min, and the temperature was 24℃. The arrays were then immersed in a 0.06M NiCl2 solution for 4min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reaction at 402℃ for 0.8h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 122℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01nm / cycle, resulting in a catalytic conversion layer.

[0066] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.52 MPa and holding it at that pressure for 1 hour, and then depressurizing it to atmospheric pressure at a rate of 0.04 MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 55 μm and a pore size of 0.2 ± 0.02 μm. The hot-pressing temperature is 150℃, the pressure is 0.6 MPa, and the time is 8 seconds, thus obtaining the cell gas absorption and enrichment material.

[0067] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0068] Comparative Example 1

[0069] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0070] S1. Take boric acid and a 2.2% (w / w) graphene oxide dispersion, with a boric acid to graphene oxide dispersion ratio of 0.5 g: 500 mL, and mix them sequentially by ultrasonication (frequency 40 kHz, time 1.1 h), hydrothermal reduction (temperature 175 ℃, time 6 h), and freeze drying (temperature -45 ℃, time 42 h) to obtain boron-doped graphene aerogel, which is used as a conductive support framework.

[0071] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0072] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0073] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0074] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2h. The hot-pressing temperature is 115℃, the pressure is 10MPa, and the time is 5min, finally obtaining a gradient adsorption layer.

[0075] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.1M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 20 min, and the temperature was 25℃. The arrays were then immersed in a 0.05M NiCl2 solution for 5 min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reacting at 400℃ for 1 h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 120℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01 nm / cycle, resulting in a catalytic conversion layer.

[0076] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.5MPa and holding it at that pressure for 1.1 hours, and then depressurizing it to atmospheric pressure at a rate of 0.03MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 145℃, the pressure is 0.5MPa, and the time is 9s, thus obtaining the cell gas absorption and enrichment material.

[0077] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0078] Comparative Example 2

[0079] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0080] S1. Boric acid and a 2.2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (40 kHz, 1.1 h), hydrothermal reduction (175 °C, 6 h), and freeze-drying (-45 °C, 42 h) to obtain boron-doped graphene aerogel. A 70% (w / w) ethanol solution was then used as a solvent to add 0.1 M LiOH and 0.03 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 11 mm / min. After dip-coating, the aerogel was sintered at 300 °C for 1.1 h under nitrogen protection to obtain a conductive support framework.

[0081] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0082] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0083] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0084] S3. An amino-modified MIL-101(Cr) slurry and a ZIF-8@ activated carbon core-shell slurry are sequentially coated on the surface of the conductive support framework. The wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm, and the wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm. Then, the substrate is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2 h. The hot-pressing temperature is 115℃, the pressure is 10 MPa, and the time is 5 min, finally obtaining a gradient adsorption layer.

[0085] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.1M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 20 min, and the temperature was 25℃. The arrays were then immersed in a 0.05M NiCl2 solution for 5 min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reacting at 400℃ for 1 h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 120℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01 nm / cycle, resulting in a catalytic conversion layer.

[0086] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.5MPa and holding it at that pressure for 1.1 hours, and then depressurizing it to atmospheric pressure at a rate of 0.03MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 145℃, the pressure is 0.5MPa, and the time is 9s, thus obtaining the cell gas absorption and enrichment material.

[0087] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0088] Comparative Example 3

[0089] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0090] S1. Boric acid and a 2.2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (40 kHz, 1.1 h), hydrothermal reduction (175 °C, 6 h), and freeze-drying (-45 °C, 42 h) to obtain boron-doped graphene aerogel. A 70% (w / w) ethanol solution was then used as a solvent to add 0.1 M LiOH and 0.03 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 11 mm / min. After dip-coating, the aerogel was sintered at 300 °C for 1.1 h under nitrogen protection to obtain a conductive support framework.

[0091] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0092] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0093] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0094] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2h. The hot-pressing temperature is 115℃, the pressure is 10MPa, and the time is 5min, finally obtaining a gradient adsorption layer.

[0095] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.1M, was used as the electrodeposition solution. MnO2 nanowire arrays were obtained by electrodeposition on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 20min, and the temperature was 25℃. Then, the arrays were immersed in a NiCl2 solution with a concentration of 0.05M for 5min. After removal, the arrays were purged with nitrogen gas and then subjected to nitriding treatment (reaction at 400℃ for 1h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray, thus obtaining the catalytic conversion layer.

[0096] S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.5MPa and holding it at that pressure for 1.1 hours, and then depressurizing it to atmospheric pressure at a rate of 0.03MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 145℃, the pressure is 0.5MPa, and the time is 9s, thus obtaining the cell gas absorption and enrichment material.

[0097] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0098] Comparative Example 4

[0099] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0100] S1. Boric acid and a 2.2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (40 kHz, 1.1 h), hydrothermal reduction (175 °C, 6 h), and freeze-drying (-45 °C, 42 h) to obtain boron-doped graphene aerogel. A 70% (w / w) ethanol solution was then used as a solvent to add 0.1 M LiOH and 0.03 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 11 mm / min. After dip-coating, the aerogel was sintered at 300 °C for 1.1 h under nitrogen protection to obtain a conductive support framework.

[0101] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0102] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0103] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0104] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2h. The hot-pressing temperature is 115℃, the pressure is 10MPa, and the time is 5min, finally obtaining a gradient adsorption layer.

[0105] S4. Take the product from step S3 and perform pre-expansion treatment and gas-permeable membrane encapsulation. Pre-expansion treatment refers to placing the product in an autoclave, filling it with N2 to 0.5 MPa and holding it at that pressure for 1.1 hours, and then depressurizing it to atmospheric pressure at a rate of 0.03 MPa / min. Gas-permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50 μm and a pore size of 0.2 ± 0.02 μm. The hot-pressing temperature is 145℃, the pressure is 0.5 MPa, and the time is 9 seconds, thus obtaining the cell gas absorption and enrichment material.

[0106] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0107] Comparative Example 5

[0108] A method for preparing a cell gas absorption and enrichment material, the method comprising the following steps:

[0109] S1. Boric acid and a 2.2% (w / w) graphene oxide dispersion were mixed sequentially by ultrasonication (40 kHz, 1.1 h), hydrothermal reduction (175 °C, 6 h), and freeze-drying (-45 °C, 42 h) to obtain boron-doped graphene aerogel. A 70% (w / w) ethanol solution was then used as a solvent to add 0.1 M LiOH and 0.03 M H3PO4, and the mixture was reacted to obtain a Li3PO4 precursor solution. The Li3PO4 precursor solution was deposited onto the surface of the boron-doped graphene aerogel using a dip-coating method at a speed of 11 mm / min. After dip-coating, the aerogel was sintered at 300 °C for 1.1 h under nitrogen protection to obtain a conductive support framework.

[0110] S2. Preparation of ZIF-8@ activated carbon core-shell particles: Activated carbon is refluxed with concentrated nitric acid and washed until neutral. Zn(NO3)2·6H2O and 2-methylimidazole are then dissolved in methanol to obtain a coating solution. Activated carbon is added to the coating solution, stirred at room temperature for 28 hours, and then centrifuged to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 82℃, and the time is 3 hours. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole, and methanol is 5.95g:6.5g:520mL, and the ratio of activated carbon to coating solution is 10g:500mL.

[0111] ZIF-8@ activated carbon core-shell particles were added to N-methylpyrrolidone, and additives were added to mix them to obtain ZIF-8@ activated carbon core-shell slurry. The slurry formulation by mass fraction was: 45% ZIF-8@ activated carbon core-shell particles, 12% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 3% hydrophobic SiO2 nanospheres, 2% multi-walled carbon nanotubes, and 35% N-methylpyrrolidone.

[0112] Cr(NO3)3·9H2O, terephthalic acid, and 2-aminoterephthalic acid were mixed (mixing mass ratio of 1:0.4:0.1) and then hydrothermally synthesized (first reacted at 150℃ for 12h, then extracted with methanol by Soxhlet for 42h, and finally activated under vacuum at 150℃) to obtain amino-modified MIL-101(Cr). This was added to N-methylpyrrolidone, and auxiliaries were added to mix and obtain amino-modified MIL-101(Cr) slurry. The slurry formulation by mass fraction was: 35% amino-modified MIL-101(Cr), 15% polyvinylidene fluoride-hexafluoropropylene copolymer, 3% lithium bis(trifluoromethanesulfonylimide), 1.5% carbon black, and 45.5% N-methylpyrrolidone.

[0113] S3. ZIF-8@ activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton. The wet film thickness of the ZIF-8@ activated carbon core-shell slurry is 100 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry is 75 μm. Then, it is vacuum dried and hot-pressed. The vacuum drying temperature is 75℃ and the time is 2h. The hot-pressing temperature is 115℃, the pressure is 10MPa, and the time is 5min, finally obtaining a gradient adsorption layer.

[0114] S4. A mixed aqueous solution of MnSO4 and Na2SO4, both with a concentration of 0.1M, was used as the electrodeposition solution to electrodeposit MnO2 nanowire arrays on the surface of the gradient adsorption layer. The electrodeposition voltage was 0.8V vs. Ag / AgCl, the time was 20 min, and the temperature was 25℃. The arrays were then immersed in a 0.05M NiCl2 solution for 5 min, removed, and purged with nitrogen. Following this, a nitriding treatment was performed (reacting at 400℃ for 1 h in an NH3 atmosphere) to obtain a MnO2-Ni3N heterojunction nanoarray. Finally, an ALD porous protective film was atomically deposited on the array surface using trimethylaluminum and deionized water as alternating precursors. The atomic layer deposition temperature was 120℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01 nm / cycle, resulting in a catalytic conversion layer.

[0115] S5. Take the product from step S4 and encapsulate it with a breathable membrane. The breathable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 50μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 145℃, the pressure is 0.5MPa, and the time is 9s, thus obtaining the cell gas absorption and enrichment material.

[0116] An anti-bulging lithium battery cell includes, in sequence, a positive electrode current collector (15μm thick aluminum foil), a positive electrode coating (using NCM622 ternary material as active material, conductive carbon black as conductive agent, and PVDF as binder), a separator (16μm thick ceramic-coated PE base film), a negative electrode coating (using artificial graphite as active material, conductive carbon black as conductive agent, and CMC / SBR as binder), a negative electrode current collector (10μm thick copper foil), and an electrolyte (1.1 mol / L LiPF6 dissolved in a mixed solvent with a volume ratio of EC:EMC=3:7), and the top sealing area of ​​the cell is provided with a gas absorption and enrichment material for the cell.

[0117] II. Performance Testing

[0118] (1) Gas adsorption capacity test

[0119] Samples of the battery cell gas absorption enrichment materials prepared in Examples 1-3 and Comparative Examples 1-5, with the same dimensions (100mm × 100mm × 0.5mm), were cut and placed together with the composite gas in a glass desiccator and sealed. The concentration changes of each gas inside the desiccator at 20°C and normal pressure were then measured using a CO2 sensor and a gas chromatograph. The gas pressure inside the desiccator was monitored in real time during the adsorption process, and the pressure was kept constant by changing the volume. Finally, the adsorption amount of each gas was measured after 27 hours.

[0120] The composition of the above-mentioned composite gas is shown in Table 1 below:

[0121] Table 1: Composition of the composite gas

[0122]

[0123] (2) Battery stability test

[0124] Take the anti-bulging lithium battery samples prepared in Examples 1-3 and Comparative Examples 1-5 respectively, charge the batteries at 1C at 45°C, let them stand for 10 minutes, and then discharge them at 1C. Repeat the charge and discharge steps, and calculate the capacity retention rate and volume expansion rate after 500 cycles according to the following formula.

[0125]

[0126]

[0127] III. Results Analysis

[0128] The results of the above gas adsorption capacity test and battery stability test are statistically summarized in Tables 2 and 3 below:

[0129] Table 2: Results of Gas Adsorption Capacity Test

[0130]

[0131] Table 3: Battery Stability Test Results

[0132]

[0133] As can be seen from Tables 2 and 3 above, Examples 1-3 of the present invention have certain adsorption activities for CO2, CO, H2, C2H4 and CH4. When applied to the adsorption of gas in the battery cell, they can meet the requirements of normal working conditions. In terms of battery stability testing, the capacity retention rate after 500 cycles is more than 88.1%, and the volume expansion rate is less than 7.9%, which is also very excellent.

[0134] Comparative Examples 1-5 were all single-factor adjustments based on Example 2. Specifically: Comparative Example 1 did not have a Li3PO4 nanolayer deposited on the conductive support framework surface, and the adsorption amounts of each gas did not change significantly. However, the volume expansion rate increased to 15.1% compared to Example 2, and the capacity retention rate decreased to 83.1%, possibly due to the influence of electrolyte permeation. In Comparative Example 2, the coating order of the two adsorption layers was changed: first, an amino-modified MIL-101(Cr) slurry was coated, followed by a ZIF-8@activated carbon core-shell slurry. This resulted in a significant decrease in the adsorption amounts of CO2, CO, and C2H4, while the volume expansion rate increased to 12.4% compared to Example 2, and the capacity retention rate decreased. The capacity retention rate also decreased to 85.3%; in Comparative Example 3, no ALD porous protective film was deposited on the surface of the catalytic conversion layer, resulting in a slight decrease in the adsorption capacity for most gases. At the same time, the volume expansion rate increased to 85.8% compared to Example 2, and the capacity retention rate decreased to 10.6%; in Comparative Example 4, the entire catalytic conversion layer was removed, resulting in a significant decrease in the adsorption capacity for CO and H2. At the same time, the volume expansion rate increased to 14.8% compared to Example 2, and the capacity retention rate decreased to 84.9%; in Comparative Example 5, the pre-expansion treatment process was omitted, and the adsorption capacity of each gas did not change significantly. However, the volume expansion rate increased to 22.7% compared to Example 2, and the capacity retention rate decreased to 80.6%.

[0135] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. An electrode gas-absorbing enrichment material, characterized by, The material is composed of a conductive support skeleton, a gradient adsorption layer coated on the surface of the conductive support skeleton, and a catalytic conversion layer deposited on the surface of the gradient adsorption layer, and is prepared after pre-expansion treatment and encapsulation with a breathable membrane. The conductive support framework is a boron-doped graphene aerogel with a Li3PO4 nanolayer deposited on its surface. The gradient adsorption layer includes a primary adsorption layer and a secondary adsorption layer coated sequentially from the inside out. The primary adsorption layer uses ZIF-8@activated carbon core-shell slurry, and the secondary adsorption layer uses amino-modified MIL-101(Cr) slurry. The catalytic conversion layer is a MnO2-Ni3N heterojunction nanoarray with an ALD porous protective film deposited on its surface. The preparation method of the cell gas absorption and enrichment material includes the following steps: S1. Boric acid and graphene oxide dispersion are ultrasonically mixed, hydrothermally reduced and freeze-dried in sequence to obtain boron-doped graphene aerogel. Then, LiOH and H3PO4 are added to ethanol solution as solvent and reacted to obtain Li3PO4 precursor solution. The Li3PO4 precursor solution is deposited on the surface of boron-doped graphene aerogel by dip-coating method to obtain conductive support framework. S2. Prepare ZIF-8@ activated carbon core-shell particles, add them to N-methylpyrrolidone, add additives, and mix to obtain ZIF-8@ activated carbon core-shell slurry; then take Cr(NO3)3·9H2O, terephthalic acid and 2-aminoterephthalic acid, mix them, and synthesize them by hydrothermal treatment to obtain amino-modified MIL-101(Cr), add it to N-methylpyrrolidone, add additives, and mix to obtain amino-modified MIL-101(Cr) slurry; S3. ZIF-8@activated carbon core-shell slurry and amino-modified MIL-101(Cr) slurry are sequentially coated on the surface of the conductive support skeleton, and then vacuum dried and hot-pressed to obtain a gradient adsorption layer. S4. A mixed aqueous solution of MnSO4 and Na2SO4 was used as the electrodeposition solution to electrodeposit MnO2 nanowire array on the surface of the gradient adsorption layer. The array was then immersed in NiCl2 solution, removed and purged with nitrogen gas. After nitriding treatment, MnO2-Ni3N heterojunction nanoarray was obtained. Finally, ALD porous protective film was deposited on the surface of the array using trimethylaluminum and deionized water as alternating precursors to obtain the catalytic conversion layer. S5. Take the product from step S4 and perform pre-expansion treatment and gas-permeable membrane encapsulation to obtain the cell gas absorption and enrichment material.

2. The cell gas absorbing enrichment material according to claim 1, characterized by, In step S1, the mass concentration of the graphene oxide dispersion is 2-2.5%, the ratio of boric acid to graphene oxide dispersion is 0.5g:450-550mL, the ultrasonic mixing frequency is 35-45kHz, the time is 1-1.2h, the hydrothermal reduction temperature is 170-180℃, the time is 5-8h, the freeze-drying temperature is -40 to -50℃, the time is 36-48h, the mass concentration of the ethanol solution is 65-75%, the added concentration of LiOH is 0.08-0.12M, and the added concentration of H3PO4 is 0.025-0.035M. The dipping and pulling method has a pulling speed of 10-12 mm / min, and after the pulling is completed, it is sintered at 295-305℃ for 1-1.2 h under nitrogen protection.

3. The cell gas absorbing enrichment material according to claim 1, characterized by, In step S2, the specific operation for preparing ZIF-8@ activated carbon core-shell particles is as follows: Take activated carbon and wash it until neutral after reflux with concentrated nitric acid. Then take Zn(NO3)2·6H2O and 2-methylimidazole and dissolve them in methanol to obtain a coating solution. Add activated carbon to the coating solution, stir at room temperature for 24-32 hours, and then centrifuge to collect ZIF-8@ activated carbon core-shell particles. The reflux temperature of the concentrated nitric acid is 80-85℃, and the time is 2.5-3.5h. The ratio of Zn(NO3)2·6H2O, 2-methylimidazole and methanol is 5.95g:6.5g:500-550mL. The ratio of activated carbon to coating solution is 10g:400-600mL.

4. The cell gas absorption and enrichment material according to claim 1, characterized in that, In step S2, the mass ratio of Cr(NO3)3·9H2O, terephthalic acid and 2-aminoterephthalic acid is 1:0.4:0.

1. The hydrothermal synthesis refers to reacting at 145-155℃ for 10-14h, followed by Soxhlet extraction with methanol for 36-48h, and finally vacuum activation at 145-155℃.

5. The cell gas absorption and enrichment material according to claim 1, characterized in that, In step S2, the additives in the ZIF-8@ activated carbon core-shell slurry include polyvinylidene fluoride-hexafluoropropylene copolymer, lithium bis(trifluoromethanesulfonyl)imide, hydrophobic SiO2 nanospheres, and multi-walled carbon nanotubes, and the mass percentages of each component are as follows: ZIF-8@ activated carbon core-shell particles 42-48%, polyvinylidene fluoride-hexafluoropropylene copolymer 10-15%, lithium bis(trifluoromethanesulfonyl)imide 2-4%, hydrophobic SiO2 nanospheres 2-4%, multi-walled carbon nanotubes 1-3%, and N-methylpyrrolidone 32-38%. The additives in the amino-modified MIL-101(Cr) slurry include polyvinylidene fluoride-hexafluoropropylene copolymer, lithium bis(trifluoromethanesulfonyl)imide, and carbon black, and the mass percentages of each component are as follows: amino-modified MIL-101(Cr) 32-38%, polyvinylidene fluoride-hexafluoropropylene copolymer 12-18%, lithium bis(trifluoromethanesulfonyl)imide 2-5%, carbon black 1-2%, and N-methylpyrrolidone 40-50%.

6. The cell gas absorption and enrichment material according to claim 1, characterized in that, In step S3, the wet film thickness of the ZIF-8@ activated carbon core-shell slurry coating is 90-110 μm, and the wet film thickness of the amino-modified MIL-101(Cr) slurry coating is 70-80 μm. The vacuum drying temperature is 70-80℃ and the time is 1.8-2.2 h. The hot pressing temperature is 110-120℃, the pressure is 8-12 MPa, and the time is 4-6 min.

7. The cell gas absorption and enrichment material according to claim 1, characterized in that, In step S4, the concentrations of MnSO4 and Na2SO4 are both 0.08-0.12M, the electrodeposition voltage is 0.8V vs. Ag / AgCl, the time is 20±2min, and the temperature is 25±1℃. The concentration of the NiCl2 solution is 0.04-0.06M, the immersion time is 4-6 min, and the nitriding treatment refers to the reaction at 398-402℃ in an NH3 atmosphere for 0.8-1.2 h. The atomic layer deposition temperature was 120±2℃, the number of cycles was 15 cycles, and the single-cycle growth rate was 0.11±0.01nm / cycle.

8. The cell gas absorption and enrichment material according to claim 1, characterized in that, In step S5, the pre-expansion treatment refers to placing the product in a high-pressure autoclave, filling it with N2 to 0.5±0.02MPa and maintaining the pressure for 1-1.2h, and then depressurizing it to atmospheric pressure at a rate of 0.02-0.04MPa / min. The permeable membrane encapsulation refers to hot-pressing the product with an ePTFE membrane with a thickness of 45-55μm and a pore size of 0.2±0.02μm. The hot-pressing temperature is 140-150℃, the pressure is 0.4-0.6MPa, and the time is 8-10s.

9. A lithium battery with anti-bulging feature, characterized in that, The cell of the anti-bulging lithium battery includes a positive current collector, a positive coating, a separator, a negative coating, a negative current collector, and an electrolyte arranged in sequence, and the top sealing area of ​​the cell is provided with a cell gas absorption and enrichment material as described in any one of claims 1-8.

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