A dual-ion battery based on MOF-on-MOF framework anode material and high-concentration dual-lithium salt electrolyte
By designing MOF-on-MOF framework compounds and high-concentration dual lithium salt electrolytes, the problems of low specific capacity and poor stability of dual-ion battery anode materials were solved, achieving high capacity and long-cycle stable electrochemical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH ZHUHAI INST OF MODERN IND INNOVATION
- Filing Date
- 2024-08-08
- Publication Date
- 2026-05-26
AI Technical Summary
The lack of suitable negative electrode materials in existing dual-ion batteries results in low specific capacity, poor stability, and weak conductivity, which limits their electrochemical performance.
A graphite/ZnMnGO-MOF@GO dual-ion battery was constructed by using MOF-on-MOF framework compounds as anode materials, combining them with graphene oxide-modified ZnMnBTC@ZIF-67 materials, and designing a high-concentration dual lithium salt electrolyte.
It achieves high capacity, long cycle stability and excellent rate performance. The discharge specific capacity reaches 175 mAh g-1 at 200 mA g-1, the capacity retention rate is as high as 106.93% after 500 cycles, and it still has 68.11 mAh g-1 at 1000 mA g-1. After 7000 stable cycles, the capacity retention rate is as high as 98.39%.
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Figure CN119039596B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of rechargeable battery energy storage technology, specifically to a dual-ion battery based on MOF-on-MOF framework anode material and high-concentration dual lithium salt electrolyte. Background Technology
[0002] In recent years, to avoid the danger of energy shortages, people have turned to developing new energy sources such as solar and wind power, which are widely available and environmentally friendly. However, while these new energy sources have the advantage of being inexhaustible, they are heavily dependent on climate and geographical location, resulting in spatial and temporal imbalances with energy consumption. Therefore, to address this imbalance, there is an urgent need for a high-performance, large-scale energy storage device.
[0003] Thanks to its working mechanism, which differs from traditional rocking chair batteries, dual-ion batteries possess higher operating voltages and can achieve higher energy densities, attracting widespread interest from researchers. The initial architecture of dual-ion batteries was based on dual graphite positive and negative electrodes; therefore, they were initially also called dual-graphite batteries. However, graphite has a relatively low specific capacity; for example, the theoretical specific capacity of LiC6 is 372 mAh g⁻¹. -1 This limits the improvement of battery energy density. Other traditional anode materials also have various drawbacks, such as large volume expansion and slow reaction kinetics. Therefore, to promote the industrialization of dual-ion batteries, it is necessary to continue developing new structurally stable, high-capacity anode materials.
[0004] MOFs are a class of crystalline materials with three-dimensional porous structures and large specific surface areas, assembled from metal nodes and organic frameworks. They are rich in porosity and have tunable pore structure, showing broad application prospects in drug separation, gas adsorption, energy conversion, and storage. However, single MOF materials also suffer from low electrical conductivity and low ion kinetics, which limit their electrochemical performance.
[0005] The MOF-on-MOF strategy can combine two or more MOFs to overcome the defects of single MOF materials, endow them with functional diversity, and thus have better electrochemical performance.
[0006] Therefore, this invention addresses the current lack of suitable anode materials for dual-ion batteries by developing a novel anode material with high capacity, excellent cycle stability, and low self-discharge rate to improve the electrochemical performance of dual-ion batteries. Summary of the Invention
[0007] To address the existing technical problems, this invention aims to provide a design method for dual-ion batteries with high capacity, excellent rate performance, and superior long-cycle performance. By preparing MOF-on-MOF framework compounds and combining the advantages of different MOFs, the shortcomings of single MOFs, such as low specific capacity, poor stability, and weak conductivity, are improved. Simultaneously, a high-concentration dual-lithium salt electrolyte is designed to construct a graphite / ZnMnGO-MOF@GO dual-ion battery. This battery system has a simple preparation method, high capacity, and good cycle stability.
[0008] To achieve the above objectives, the technical solution of the present invention is as follows.
[0009] A method for preparing anode materials based on MOF-on-MOF frameworks includes the following steps:
[0010] (1) Dissolve pyromellitic acid, zinc nitrate hexahydrate, manganese nitrate tetrahydrate and polyvinylpyrrolidone in methanol / N,N-dimethylformamide solution;
[0011] (2) Dissolve dimethylimidazole and cobalt nitrate hexahydrate in methanol / N,N-dimethylformamide solution to obtain solution B;
[0012] (3) Add solution A to solution B and add graphene oxide. Stir the reaction to obtain graphene oxide modified ZnMnBTC@ZIF-67 material (ZnMnGO-MOF@GO), which is the negative electrode material.
[0013] Preferably, the molar ratio of the pyromellitic acid, zinc nitrate hexahydrate, and manganese nitrate tetrahydrate is 2–8:2:1.
[0014] Preferably, the amount of polyvinylpyrrolidone added is 2.0g-4.0g.
[0015] Preferably, the molar ratio of dimethylimidazole to cobalt nitrate hexahydrate is 6-12:1.
[0016] Preferably, the mass ratio of graphene oxide to cobalt nitrate hexahydrate is 1:5-40, and more preferably 1:14.5.
[0017] Preferably, the reaction temperature is 120-180℃ and the reaction time is 6-12h.
[0018] Preferably, the preparation method of the MOF-on-MOF framework-based anode material includes the following steps:
[0019] 0.42 g of trimesic acid, 0.30 g of zinc nitrate hexahydrate, 0.13 g of manganese nitrate tetrahydrate, and 3.0 g of polyvinylpyrrolidone were dissolved in 50 mL of methanol / N,N-dimethylformamide (DMF) solution to obtain solution A. Then, 1.64 g of dimethylimidazole and 0.73 g of cobalt nitrate hexahydrate were dissolved in 50 mL of methanol / DMF solution to obtain solution B. Solution A was added to solution B, along with 0.02 g–0.05 g of graphene oxide. The mixture was sonicated for 10–15 min, stirred for 30–60 min, and then reacted in a polytetrafluoroethylene reactor at 120–180 °C for 6–12 h. After cooling, the mixture was centrifuged, and the sample was collected to obtain ZnMnGO-MOF@GO.
[0020] A negative electrode material prepared by any of the above preparation methods.
[0021] A dual-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte between the positive electrode and the negative electrode; the negative electrode uses the graphene oxide-modified ZnMnBTC@ZIF-67 material as the active material; the electrolyte is composed of a solvent and a dual lithium salt electrolyte.
[0022] Preferably, the concentration of lithium salt 1 in the electrolyte is 2.0–6.0 mol / L. -1 Further preferred is 4 mol L -1 The concentration of lithium salt 2 is 0.1–2.0 mol / L. -1 Further preferred is 1.0 mol L. -1 .
[0023] Preferably, the molar ratio of lithium salt 1 to lithium salt 2 is 4-8:1.
[0024] Preferably, the lithium salt is any two of lithium hexafluorophosphate (LiPF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI), and more preferably LiTFSI and LiFSI.
[0025] Preferably, the solvent is a mixed solvent system of ionic liquid and carbonate solvent with a volume ratio of 1:1 to 10.
[0026] Preferably, the ionic liquid is Pyr 14 TFSI, PP 14 One or more of TFSI and EMImTFSI, preferably Pyr 14 TFSI.
[0027] Preferably, the carbonate solvent is three or more of ethylene carbonate (EC), methyl ethyl carbonate (EMC), propylene carbonate (PC), dimethyl carbonate (DMC), and diethyl carbonate (DEC), more preferably methyl ethyl carbonate, dimethyl carbonate, and diethyl carbonate, denoted as EDD, and preferably in a ratio of 1:1:1.
[0028] Preferably, the negative electrode comprises a current collector, an active material, a conductive agent, and a binder.
[0029] Preferably, the positive electrode comprises a current collector, an active material, a conductive agent, and a binder.
[0030] Preferably, the current collector is copper foil or aluminum foil, the conductive agent is one or more of Super P, graphite powder, and acetylene black, and the binder is polyvinylidene fluoride.
[0031] Preferably, the active material of the positive electrode is composed of graphite material.
[0032] Preferably, the graphite material is one or more of natural graphite, artificial graphite, expanded graphite and mesophase carbon microspheres, and more preferably natural graphite.
[0033] Preferably, the diaphragm includes one or more of polypropylene diaphragms, glass fiber diaphragms, and nonwoven fabric diaphragms, and more preferably glass fiber diaphragms.
[0034] Assembly of a dual-ion battery: Using natural graphite as the positive electrode, paired with ZnMnGO-MOF@GO negative electrode and dual lithium salt electrolyte, the battery is assembled in a glove box under argon protection.
[0035] Preferably, the electrolyte composition is 4M LiTFSI + 1.0M LiFSI, and the solvent system is preferably EDD:Pyr 14 TFSI = 1:1 (volume ratio).
[0036] Preferably, the amount of electrolyte used is 80-120 μL, and more preferably 100 μL.
[0037] The above-described dual-ion batteries are used in battery-powered vehicles, mobile devices, or energy storage devices.
[0038] Compared with the prior art, the present invention has the following beneficial effects:
[0039] (1) This invention synthesizes core-shell structured microspherical anode materials via a simple solvothermal method, and assembles them into a graphite / ZnMnGO-MOF@GO dual-ion battery by combining them with a graphite cathode and a high-concentration dual-lithium salt electrolyte. This design method is simple to operate, uses widely available raw materials, and has low cost.
[0040] (2) The double lithium salt electrolyte designed in this invention has a wide electrochemical window and can effectively prevent solvent co-intercalation and protect the negative electrode structure.
[0041] (3) The dual-ion battery of the present invention operates at 200 mA g -1 Achieving 175mAh g at high current density. -1 High discharge specific capacity; after 500 cycles, the discharge specific capacity is 187.14 mAh g. -1 It boasts a capacity retention rate as high as 106.93%, and excellent rate performance at 1000 mA g. -1 Achieving 68.11 mAh g at a current density. -1 After 7000 stable cycles, the capacity still remains at 67.01 mAh g. -1 The median discharge voltage is 2.59V, and the capacity retention rate is as high as 98.39%. Attached Figure Description
[0042] Figure 1 This is a scanning electron microscope image of ZnMnGO-MOF@GO.
[0043] Figure 2 This is a transmission electron microscope (TEM) image of ZnMnGO-MOF@GO.
[0044] Figure 3 The graphs show the initial charge-discharge curves and cycle performance curves of the batteries in Example 1, Comparative Example 1, and Comparative Example 2.
[0045] Figure 4 The graphs show the initial charge-discharge curves and cycle performance curves of the batteries in Examples 2, 3, and 3.
[0046] Figure 5 For Example 3 and Comparative Example 4, the current density was 200 mA g -1 The initial charge-discharge curves and cycle performance curves are shown.
[0047] Figure 6 This is a graph showing the long-cycle performance of the battery in Example 3. Detailed Implementation
[0048] To facilitate understanding of the present invention, it is further described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0049] Example 1: A method for preparing a ZnMnGO-MOF@GO / lithium half-ion battery, comprising the following steps:
[0050] (1) Dissolve 0.42 g of trimesic acid, 0.30 g of zinc nitrate hexahydrate, 0.13 g of manganese nitrate tetrahydrate, and 3.0 g of polyvinylpyrrolidone in 50 mL of methanol / N,N-dimethylformamide (DMF) solution (where the volume ratio of methanol to DMF is 1:1) to obtain solution A; then dissolve 1.64 g of dimethylimidazole and 0.73 g of cobalt nitrate hexahydrate in 50 mL of methanol / DMF solution (where the volume ratio of methanol to DMF is 1:1) to obtain solution B. Add solution A to solution B, add 0.05 g of graphene oxide, sonicate for 10 min, stir for 30 min, and react in a polytetrafluoroethylene reactor at 160 °C for 6 h. After cooling, centrifuge and collect the sample to obtain ZnMnGO-MOF@GO composite material.
[0051] (2) The porous spherical ZnMnGO-MOF@GO composite material obtained in step (1), Super P and polyvinylidene fluoride were mixed in a mass ratio of 7:2:1 and dissolved in 2.4g of N-methylpyrrolidone to form a fluid slurry. The slurry was stirred at 600r / min for 10h and then coated onto copper foil. The surface solvent was removed by drying at 80℃ in a forced-air drying oven for 1h and then transferred to a vacuum drying oven at 100℃ for 12h. After complete drying, the electrode was cut into small round pieces with a diameter of 14mm using a punching machine and placed in a glove box as the negative electrode.
[0052] (3) A half-cell was assembled in a glove box using ZnMnGO-MOF@GO as the working electrode and lithium metal sheet as the counter and reference electrodes. 1M LiTFSI (EC:DEC:DMC) was used as the electrolyte, and the electrolyte was applied at 200mA g / L within a voltage range of 0.01-3.0V. -1 Electrochemical performance was tested at a current density.
[0053] Comparative Example 1: A method for preparing a ZIF-67 / lithium half-ion battery, comprising the following steps:
[0054] (1) Dissolve 20 mmol dimethylimidazole (1.64 g) in 50 mL of methanol, then add 2.5 mmol cobalt nitrate hexahydrate, stir to dissolve, stir for 6 h, then let stand for 24 h, centrifuge and wash with methanol to obtain purple sample ZIF-67.
[0055] (2) The dodecahedral ZIF-67, Super P, and polyvinylidene fluoride obtained in step (1) were mixed in a mass ratio of 7:2:1 and dissolved in 2.4 g of N-methylpyrrolidone to form a fluid slurry. The slurry was stirred at 600 r / min for 10 h and then coated onto copper foil. The surface solvent was removed by drying in a forced-air drying oven at 80 °C for 1 h, and then transferred to a vacuum drying oven at 80 °C for 12 h. After complete drying, the electrode was cut into small round pieces with a diameter of 14 mm using a die-cutting machine and placed in a glove box as the negative electrode.
[0056] (3) A half-cell was assembled in a glove box using ZIF-67 negative electrode as working electrode and lithium metal sheet as counter and reference electrode. 1M LiTFSI (EC:DEC:DMC) was used as electrolyte. Electrochemical performance was tested at a current density of 200 mAg⁻¹ within a voltage range of 0.01-3.0V.
[0057] Comparative Example 2: A method for preparing a ZnMnBTC / lithium half-ion battery, comprising the following steps:
[0058] (1) Weigh 2 mmol of pyromellitic acid (0.4206 g), 1.0 mmol of zinc nitrate hexahydrate, 0.5 mmol of manganese nitrate tetrahydrate, and 3.0 g of polyvinylpyrrolidone in sequence and dissolve them in 50 mL of N,N-dimethylformamide solution. Stir to dissolve, and after 30 min, transfer to a reaction vessel. React at 160 °C for 6 h. After cooling, centrifuge and wash with deionized water to obtain white ZnMnBTC.
[0059] (2) A negative electrode was prepared using ZnMnBTC, SuperP, and polyvinylidene fluoride in a ratio of 70:20:10 and used as the working electrode. A lithium metal sheet was used as the counter electrode and reference electrode. A half-cell was assembled in a glove box, using 1M LiTFSI (EC:DEC:DMC) as the electrolyte. The electrolyte was applied at a voltage range of 0.01-3.0V at 200mA g. -1 Electrochemical performance was tested at a current density.
[0060] Example 2: A method for preparing a graphite / ZnMnGO-MOF@GO dual-ion battery, comprising the following steps:
[0061] (1) Weigh 0.9g of graphite powder, 0.02g of acetylene black, and 0.08g of polyvinylidene fluoride in a mass ratio of 90:2:8, mix and stir to form a fluid slurry, dissolve in 2.56g of N-methylpyrrolidone, and then coat it onto aluminum foil. First, dry it in a forced-air drying oven at 80℃ for 1h to remove the surface solvent, and then transfer it to a vacuum drying oven at 80℃ for 12h. After complete drying, use a die-cutting machine to cut the electrode into small round pieces with a diameter of 14mm and place them in a glove box.
[0062] (2) Preparation of electrolyte: The organic solvent system is composed of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. After thorough mixing, the organic solvent is mixed with the ionic liquid (Pyr 14 Mix 8.0 mmol LiTFSI and 1.0 mmol LiFSI in 2 mL of the hybrid solvent system and stir until homogeneous to obtain a clear and transparent electrolyte of 4 M LiTFSI + 0.5 M LiFSI.
[0063] (3) Using graphite as the positive electrode, combined with the electrolyte prepared in step (2), glass fiber membrane and ZnMnGO-MOF@GO negative electrode prepared in Example 1, CR2025 button cells were assembled in a glove box under argon protection.
[0064] (5) The electrochemical performance of the button cell was tested using the Newway button cell test system within the voltage range of 1.0-4.6V.
[0065] Example 3: Preparation method of graphite / ZnMnGO-MOF@GO dual-ion battery, including the following steps
[0066] (1) Weigh 0.9g of graphite powder, 0.02g of acetylene black, and 0.08g of polyvinylidene fluoride in a mass ratio of 90:2:8, mix and stir to form a fluid slurry, dissolve in 2.56g of N-methylpyrrolidone, and then coat it onto aluminum foil. First, dry it in a forced-air drying oven at 80℃ for 1h to remove the surface solvent, and then transfer it to a vacuum drying oven at 80℃ for 12h. After complete drying, use a die-cutting machine to cut the electrode into small round pieces with a diameter of 14mm and place them in a glove box.
[0067] (2) Preparation of electrolyte: The organic solvent system is composed of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. After thorough mixing, the organic solvent is mixed with the ionic liquid (Pyr 14 Mix 8.0 mmol LiTFSI and 2.0 mmol LiFSI in 2 mL of the hybrid solvent system and stir until homogeneous to obtain a clear and transparent electrolyte of 4 M LiTFSI + 1.0 M LiFSI.
[0068] (3) Using graphite as the positive electrode, and in combination with the electrolyte prepared in step (2), a glass fiber separator, and the ZnMnGO-MOF@GO negative electrode prepared in Example 1, a CR2025 coin cell was assembled in a glove box under argon protection.
[0069] (4) The electrochemical performance of the button cell was tested using the Newway button cell test system within the voltage range of 1.0-4.6V.
[0070] Comparative Example 3: A method for preparing a graphite / ZnMnGO-MOF@GO dual-ion battery, comprising the following steps:
[0071] (1) Weigh 0.9g of graphite powder, 0.02g of acetylene black, and 0.08g of polyvinylidene fluoride in a mass ratio of 90:2:8, mix and stir to form a fluid slurry, dissolve in 2.56g of N-methylpyrrolidone, and then coat it onto aluminum foil. First, dry it in a forced-air drying oven at 80℃ for 1h to remove the surface solvent, and then transfer it to a vacuum drying oven at 80℃ for 12h. After complete drying, use a die-cutting machine to cut the electrode into small round pieces with a diameter of 14mm and place them in a glove box.
[0072] (2) Preparation of electrolyte: The organic solvent system is composed of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. After thorough mixing, the organic solvent is mixed with the ionic liquid (Pyr 14 Mix 8.0 mmol LiTFSI in 2 mL of the hybrid solvent system and stir until homogeneous to obtain a clear and transparent 4 M LiTFSI electrolyte.
[0073] (3) Using graphite as the positive electrode, and in combination with the electrolyte prepared in step (2), a glass fiber separator, and the ZnMnGO-MOF@GO negative electrode prepared in Example 1, a CR2025 coin cell was assembled in a glove box under argon protection.
[0074] (4) The electrochemical performance of the button cell was tested using the Newway button cell test system within the voltage range of 1.0-4.6V.
[0075] Comparative Example 4: The preparation method of the graphite / ZnMnGO-MOF dual-ion battery includes the following steps:
[0076] (1) Dissolve 0.42 g of trimesic acid, 0.30 g of zinc nitrate hexahydrate, 0.13 g of manganese nitrate tetrahydrate, and 3.0 g of polyvinylpyrrolidone in 50 mL of methanol / N,N-dimethylformamide (DMF) solution (where the volume ratio of methanol to DMF is 1:1) to obtain solution A; then dissolve 1.64 g of dimethylimidazole and 0.73 g of cobalt nitrate hexahydrate in 50 mL of methanol / DMF solution (where the volume ratio of methanol to DMF is 1:1) to obtain solution B. Add solution A to solution B, sonicate for 10 min, stir for 30 min, and react in a polytetrafluoroethylene reactor at 160 °C for 6 h. After cooling, centrifuge and collect the sample to obtain ZnMnGO-MOF.
[0077] (2) The porous spherical ZnMnGO-MOF, Super P, and polyvinylidene fluoride obtained in step (1) were mixed in a mass ratio of 7:2:1 and dissolved in 2.4 g of N-methylpyrrolidone to form a fluid slurry. The slurry was stirred at 600 r / min for 10 h and then coated onto copper foil. The surface solvent was removed by drying in a forced-air drying oven at 80 °C for 1 h, and then transferred to a vacuum drying oven at 100 °C for 12 h. After complete drying, the electrode was cut into small round pieces with a diameter of 14 mm using a punching machine and placed in a glove box as the negative electrode.
[0078] (3) Electrolyte preparation: The organic solvent system is composed of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a volume ratio of 1:1:1. After thorough mixing, the organic solvent is mixed with the ionic liquid (Pyr 14 Mix 8.0 mmol LiTFSI and 2.0 mmol LiFSI in 2 mL of the hybrid solvent system and stir until homogeneous to obtain a clear and transparent electrolyte of 4 M LiTFSI + 1.0 M LiFSI.
[0079] (4) Using graphite as the positive electrode, along with the electrolyte prepared in step (3), a glass fiber separator, and the ZnMnGO-MOF negative electrode prepared in step (2), CR2025 coin cells were assembled in a glove box under argon protection.
[0080] (5) The electrochemical performance of the button cell was tested using the Newway button cell test system within the voltage range of 1.0-4.6V.
[0081] Figure 1 The image shows a scanning electron microscope (SEM) image of the ZnMnGO-MOF@GO prepared in Example 1. It exhibits a microsphere shape, which is beneficial for ion transport and contact with the electrolyte. Furthermore, the structure of the material was observed using transmission electron microscopy (TEM), as shown below. Figure 2 As shown, it exhibits a core-shell structure, which will help alleviate volume expansion during charging and discharging, providing space for lithium-ion intercalation.
[0082] Figure 3 Examples 1, 1, and 2 are shown at 100 mA g. -1 The initial charge-discharge curves and corresponding cycle performance at the specified current density were obtained. Thanks to the designed synthesis strategy, Example 1 showed a significant improvement in electrochemical performance compared to Comparative Examples 1 and 2, with a discharge specific capacity of 1304.51 mAh g⁻¹. -1 This is far superior to Comparative Example 1 and Comparative Example 2, with a discharge specific capacity of 219.68 mAh g. -1 ) and 864.82mAh g -1This indicates a significant improvement in lithium storage capacity. Furthermore, its cycle performance shows that Example 1 exhibits better stability and higher capacity during charge-discharge cycles, demonstrating that Example 1 possesses higher specific capacity and superior cycle performance.
[0083] Figure 4 The charge-discharge curves and cycle performance of Examples 2, 3, and Comparative Example 3 are shown, with a test current density of 400 mA g. -1 Clearly, the addition of LiFSI effectively improved the discharge specific capacity and slowed down the capacity decay rate. The main reasons are likely twofold: first, the addition of LiFSI creates a synergistic effect between the two anions, effectively increasing the battery capacity; second, the addition of LiFSI increases the electrolyte concentration, forming a locally high-concentration electrolyte, reducing solvation, thereby improving the structural stability of the material and optimizing cycle stability.
[0084] Figure 5 Examples 3 and 4 are shown in the figure at a current density of 200 mA g. -1 The initial charge-discharge curves and cycle performance of Comparative Example 4 are shown in the figure. It can be seen from the figure that the initial discharge specific capacity of Comparative Example 4 is only 121.57 mAh g. -1 The initial discharge specific capacity of Example 3 can reach 175 mAh g. -1 This is far superior to Comparative Example 4. After 500 cycles, the discharge specific capacity of Example 3 was 187.14 mAh g. -1 The discharge specific capacity of Comparative Example 4 was 146.81 mAh g. -1 This indicates that the addition of graphene oxide effectively enhances the ionic conductivity of the material, thereby increasing the specific discharge capacity of the battery.
[0085] Figure 6 Example 3 demonstrates long-cycle performance at high current density, with the battery at 1.0 A g. -1 The battery underwent constant current charge-discharge cycling at a specific current density. The initial discharge specific capacity was 68.11 mAh g⁻¹. After a brief capacity decrease, the capacity steadily increased, achieving a coulombic efficiency exceeding 99%. After 7000 stable cycles, the capacity remained at 67.01 mAh g⁻¹. -1 With a median discharge voltage of 2.59V and a capacity retention rate as high as 98.39%, this battery demonstrates outstanding fast charging and cycle performance, and has good application potential in large-scale energy storage devices.
[0086] The above embodiments do not limit the scope of protection of this invention. Any equivalent modifications made based on the content of this specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this invention.
Claims
1. A dual-ion battery, characterized in that, The apparatus includes a positive electrode, a negative electrode, a separator, and an electrolyte between the positive and negative electrodes; the negative electrode uses graphene oxide-modified ZnMnBTC@ZIF-67 material as the active material; the electrolyte is composed of a solvent and a double lithium salt electrolyte; the preparation method of the graphene oxide-modified ZnMnBTC@ZIF-67 material includes the following steps: (1) Dissolve pyromellitic acid, zinc nitrate hexahydrate, manganese nitrate tetrahydrate and polyvinylpyrrolidone in methanol / N,N-dimethylformamide solution to obtain solution A; (2) Dissolve dimethylimidazole and cobalt nitrate hexahydrate in methanol / N,N-dimethylformamide solution to obtain solution B; (3) Add solution A to solution B and add graphene oxide. Stir the reaction to obtain graphene oxide modified ZnMnBTC@ZIF-67 material, which is the negative electrode material.
2. The dual-ion battery according to claim 1, characterized in that, The molar ratio of the pyromellitic acid, zinc nitrate hexahydrate, and manganese nitrate tetrahydrate is 2–8:2:1; The molar ratio of dimethylimidazole to cobalt nitrate hexahydrate is 6-12:1; The mass ratio of graphene oxide to cobalt nitrate hexahydrate is 1:5-40.
3. A dual-ion battery according to claim 1, characterized in that, The reaction temperature is 120-180℃, and the reaction time is 6-12 h.
4. A dual-ion battery according to claim 1, characterized in that, The concentration of lithium salt 1 in the electrolyte is 2.0–6.0 mol / L. -1 The concentration of lithium salt 2 is 0.1–2.0 mol / L. -1 The molar ratio of lithium salt 1 to lithium salt 2 is 4-8:
1.
5. A dual-ion battery according to claim 1, characterized in that, The lithium salt is any two of lithium hexafluorophosphate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide.
6. A dual-ion battery according to claim 1, characterized in that, The solvent used is a mixed solvent system of ionic liquid and carbonate solvent with a volume ratio of 1:1 to 10; the ionic liquid is Pyr 14 TFSI, PP 14 One or more of TFSI and EMImTFSI; the carbonate solvent is three or more of ethylene carbonate, ethyl methyl carbonate, propylene carbonate, dimethyl carbonate and diethyl carbonate.
7. A dual-ion battery according to claim 1, characterized in that, The active material of the positive electrode is composed of graphite material; the graphite material is one or more of natural graphite, artificial graphite, expanded graphite and mesophase carbon microspheres.
8. The application of the dual-ion battery according to any one of claims 1-7 in a battery vehicle, mobile device or energy storage device.