In-situ electro-polymerization of positive electrode for dual-ion battery, battery and preparation method and application thereof

Abstract

The application discloses a positive electrode of a dual-ion battery, a battery, and a preparation method and application thereof. The dual-ion battery comprises a positive electrode, and the positive electrode comprises a positive electrode material layer, wherein the positive electrode material layer comprises a polymer generated by in-situ electro-polymerization reaction of an active material; and the active material is selected from carbazole and / or carbazole derivatives. In the application, the active material in the positive electrode undergoes in-situ electro-polymerization reaction during charging, and is converted from a small molecule into a polymer, thereby reducing the solubility in an electrolyte, improving the energy storage stability of the positive electrode, and enabling the dual-ion battery containing the positive electrode to have excellent specific capacity and cycle stability. In the application, the positive electrode and the negative electrode of the dual-ion battery store anions and cations, respectively, during operation. The embedding and de-embedding of large-size anions (bisfluorosulfonylimide ions / bistrifluoromethanesulfonylimide ions) enable the battery to have a high working voltage, excellent specific capacity and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to the in-situ electropolymerization cathode of dual-ion batteries, the battery itself, its preparation method, and its applications. Background Technology

[0002] Lithium-ion batteries are widely used in 3C electronic products and new energy transportation. However, the scarcity and increasing mining costs of resources such as cobalt and nickel, required for lithium-ion battery cathode materials, limit the large-scale application of traditional lithium-ion batteries. Dual-ion batteries, with their advantages of low-cost and abundant graphite cathodes, have attracted widespread attention. The working principle of dual-ion batteries differs from that of traditional lithium-ion batteries. During charging and discharging, lithium ions in traditional lithium-ion batteries undergo a reversible "rocking chair" intercalation / deintercalation between the positive and negative electrodes. In dual-ion batteries, the anions and cations reversibly intercalate / deintercalate into / out of the positive and negative electrodes, respectively. This results in a higher operating voltage for dual-ion batteries compared to lithium-ion batteries, potentially leading to higher energy density. However, the size of anions in the electrolyte is typically large. The intercalation of large anions and solvent co-intercalation cause traditional graphite cathodes to suffer from insufficient theoretical capacity, poor cycle performance, and slow kinetics, which to some extent limits the development of dual-ion batteries. To overcome the performance bottlenecks of traditional graphite cathodes, small-molecule organic materials have become a research hotspot due to their wide availability and low cost of raw materials such as C, H, O, and N, as well as the designable and diverse molecular energy storage sites. While screening and designing small-molecule organic materials can achieve efficient energy storage, current small-molecule organic materials generally suffer from problems such as easy solubility and insufficient stability. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a positive electrode in which the active material in the positive electrode can undergo an in-situ electropolymerization reaction during charging to form a polymer, thereby solving the problem of poor battery performance caused by the easy dissolution of small molecule organic positive electrodes. In addition, the stability of the positive electrode material can be further improved after the active material undergoes an in-situ electropolymerization reaction to form a polymer.

[0004] The second objective of this invention is to provide a dual-ion battery.

[0005] The third objective of this invention is to provide a method for preparing a dual-ion battery.

[0006] The fourth objective of this invention is to provide an application of a dual-ion battery in electronic products or new energy transportation equipment.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A first aspect of the present invention provides a positive electrode comprising a positive electrode material layer, said positive electrode material layer comprising a polymer generated by in-situ electropolymerization of an active material; said active material is selected from carbazole, 9-phenylcarbazole, 9-benzylcarbazole, 7H-benzocarbazole, N-ethylcarbazole, N-vinylcarbazole, polyvinylcarbazole, 3,9-bicarbazole, 11,12-dihydroindolo[2,3-a]carbazole, 5,11-dihydroindolo[2,3-a]carbazole, etc. At least one of the following: 3,2-b]carbazole, 1,3-dihydroindolo[2,3-b]carbazole, 11,12-dihydro-11-phenylindolo[2,3-a]carbazole, 5-phenyl-5,12-dihydroindolo[3,2-a]carbazole, 5,11-diphenyl-5,11-dihydroindolo[3,2-b]carbazole, and 10,15-dihydro-5H-diindolo[3,2-a:3',2'-c]carbazole.

[0009] In this invention, the active material of the positive electrode is carbazole or a carbazole derivative. The positive electrode is made from this active material, and the assembled dual-ion battery can undergo in-situ electropolymerization during charging. Specifically, during charging, the activity at positions 3 and 6 of the carbon atom in the carbazole group increases, and in-situ electropolymerization occurs at positions 3 and 6 between the two active material molecules, forming a polymer product. Compared to small-molecule active materials, the solubility of the polymer product in the electrolyte is significantly reduced, thereby improving the stability of the positive electrode material. Simultaneously, through this simple in-situ electropolymerization reaction, the theoretical specific capacity of a single energy storage site can be increased, thus achieving high-capacity, long-cycle energy storage.

[0010] Preferably, the positive electrode material layer further includes a conductive agent and a binder.

[0011] Preferably, the mass ratio of the active material, conductive agent, and binder is (5-7):(2-4):1; more preferably, the mass ratio of the active material, conductive agent, and binder is (5.2-6.8):(2.2-3.8):1; even more preferably, the mass ratio of the active material, conductive agent, and binder is (5.5-6.5):(2.5-3.5):1; more preferably, the mass ratio of the active material, conductive agent, and binder is (5.8-6.2):(2.8-3.2):1.

[0012] Preferably, the conductive agent is selected from at least one of conductive carbon black, graphene, carbon nanotubes, and carbon nanofibers.

[0013] Preferably, the conductive carbon black is selected from Super P and acetylene black.

[0014] Preferably, the adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, carboxylated styrene-butadiene latex, sodium alginate, polyvinyl alcohol, and polyurethane.

[0015] Preferably, the positive electrode further includes a current collector; the positive electrode material layer is disposed on the current collector.

[0016] Preferably, the current collector is selected from elemental metals or metal alloys. Preferably, the elemental metal is selected from at least one of aluminum, copper, titanium, nickel, manganese, zinc, and tin.

[0017] Preferably, the metal alloy is selected from at least one of copper-aluminum alloy, nickel-titanium alloy, zinc-tin alloy, and nickel-manganese alloy.

[0018] Preferably, the positive electrode is prepared by: making an active material, a binder, and a conductive agent into a slurry, and then coating it onto the current collector.

[0019] A second aspect of the present invention provides a dual-ion battery comprising the positive electrode provided in the first aspect of the present invention.

[0020] The dual-ion battery in this invention refers to a battery in which anions and cations in the electrolyte can reversibly insert into / extract from the positive and negative electrodes, respectively, during the charging / discharging process.

[0021] Preferably, the battery further includes a negative electrode, an electrolyte, and a separator; the separator is located between the positive electrode and the negative electrode; and the space between the positive electrode and the negative electrode is filled with electrolyte.

[0022] Preferably, the material of the negative electrode is selected from lithium, sodium, or potassium.

[0023] Preferably, the electrolyte comprises a metal salt and an organic solvent.

[0024] Preferably, the concentration of the metal salt is 1–7 mol / L; more preferably, the concentration of the metal salt is 2–6 mol / L; and even more preferably, the concentration of the metal salt is 4–6 mol / L.

[0025] Preferably, the metal salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, potassium bis(fluorosulfonyl)imide, and potassium bis(trifluoromethanesulfonyl)imide.

[0026] Preferably, the organic solvent is selected from at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, dimethyl sulfite, methyl formate, methyl acetate, N,N-dimethylacetamide, methyl propionate, ethyl tetrahydrofuran-2-ethyl acetate, 2-methyltetrahydrofuran, 1,3-dioxolane, dimethoxymethane, 1,2-dimethoxypropane, 4-methyl-1,3-dioxolane, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, 12-crown ether-4, dimethyl sulfoxide, dimethyl ether, ethyl propionate, ethylene sulfite, propylene sulfite, diethyl sulfite, and γ-butyrolactone; more preferably, the organic solvent is a mixed solvent of ethylene carbonate and dimethyl carbonate; more preferably, the organic solvent is a mixed solvent of ethylene carbonate and dimethyl carbonate in a mass ratio of 1:(0.8-1.2).

[0027] Preferably, the diaphragm is selected from at least one of polyethylene film, polypropylene film, cellulose composite film, glass fiber film, polyvinylidene fluoride film, nonwoven fabric, alumina ceramic diaphragm, and polyethylene-polypropylene composite film.

[0028] Preferably, the dual-ion battery is selected from lithium-based dual-ion batteries, potassium-based dual-ion batteries, and sodium-based dual-ion batteries.

[0029] Preferably, the dual-ion battery includes a positive electrode shell, an anti-corrosion layer, a positive electrode, a separator, a negative electrode, a spring sheet, a gasket, and a negative electrode shell stacked in sequence, with an electrolyte filling the space between the positive and negative electrodes.

[0030] Preferably, the anti-corrosion layer is made of aluminum foil.

[0031] A third aspect of the present invention provides a method for preparing the dual-ion battery provided in the second aspect of the present invention, comprising the following steps:

[0032] The positive electrode, negative electrode, separator, and electrolyte are assembled into a battery, and then the active material is subjected to an in-situ electropolymerization reaction to obtain the dual-ion battery.

[0033] In the dual-ion battery of this invention, the active material is polymerized through in-situ electropolymerization. During subsequent battery charging and discharging, the active material in the positive electrode stores energy in the form of the polymer product, thus effectively reducing the solubility of small molecules and improving energy storage stability. Furthermore, the in-situ electropolymerization reaction can increase the theoretical specific capacity of a single energy storage site, thereby achieving high-capacity, long-cycle energy storage.

[0034] Preferably, the voltage of the in-situ electropolymerization reaction is 1.5 to 5V; more preferably, the voltage of the in-situ electropolymerization reaction is 1.8 to 4.6V.

[0035] Preferably, the in-situ electropolymerization reaction rate is 20-500 mA / g; more preferably, the in-situ electropolymerization reaction rate is 20-300 mA / g; even more preferably, the in-situ electropolymerization reaction rate is 20-100 mA / g; more preferably, the in-situ electropolymerization reaction rate is 45-55 mA / g.

[0036] Preferably, the number of cycles of the in-situ electropolymerization reaction is 1 to 20; more preferably, the number of cycles of the in-situ electropolymerization reaction is 5 to 15; even more preferably, the number of cycles of the in-situ electropolymerization reaction is 5 to 9; more preferably, the number of cycles of the in-situ electropolymerization reaction is 7 to 9.

[0037] Preferably, the voltage of the in-situ electropolymerization reaction is 1.5 to 5V, the multiplier is 20 to 500 mA / g, and the number of cycles is 1 to 20.

[0038] Preferably, the voltage of the in-situ electropolymerization reaction is 1.8 to 4.6 V, the multiplier is 45 to 55 mA / g, and the number of cycles is 7 to 9.

[0039] Under the voltage range, rate range, and cycle number conditions of this invention, the degree of in-situ electropolymerization of the positive electrode active material in the dual-ion battery is appropriate and relatively high, which can further improve the specific capacity and cycle stability of the battery.

[0040] The fourth aspect of the present invention provides the application of the dual-ion battery provided in the second aspect of the present invention in electronic products or new energy transportation equipment.

[0041] The beneficial effects of this invention are as follows: The active material in the cathode undergoes in-situ electropolymerization during charging, transforming from small molecules into polymers. This reduces its solubility in the electrolyte, improves cathode stability, and enables dual-ion batteries containing this cathode to exhibit excellent specific capacity and cycle stability. Furthermore, in-situ electropolymerization can enhance the theoretical specific capacity of individual active sites, thereby increasing energy storage capacity and ultimately achieving stable high-capacity energy storage. In addition, the active material in this invention has the advantages of wide availability of raw materials, low cost, and designable and diverse molecular energy storage sites, which can effectively reduce battery costs.

[0042] The positive and negative electrodes of the dual-ion battery of this invention store anions and cations respectively during operation. The insertion and extraction of large-sized anions enable the battery to have a higher operating voltage, improve the battery's energy density and power density, and give the battery excellent specific capacity and cycle stability. Attached Figure Description

[0043] Figure 1 The infrared spectra of the lithium-based dual-ion battery in Example 1 at different charging voltages are shown.

[0044] Figure 2 The image shows the CV curves of the lithium-based dual-ion battery in Example 1 at different cycling counts.

[0045] Figure 3 The images show SEM images of the positive electrode sheet in Example 1 before and after the in-situ electropolymerization reaction.

[0046] Figure 4 This is a charge-discharge curve of the lithium-based dual-ion battery in Example 1.

[0047] Figure 5 This is a cycle capacity curve of the lithium-based dual-ion battery in Example 1. Detailed Implementation

[0048] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described in detail below are those that can be implemented or understood by those skilled in the art by referring to the prior art. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0049] Example 1

[0050] The lithium-based dual-ion battery in this example is made by sequentially stacking a positive electrode shell, an aluminum foil anti-corrosion layer, a positive electrode sheet, a separator, a negative electrode sheet, a spring sheet, a gasket, and a negative electrode shell, and then encapsulating them, with an electrolyte filling the space between the positive and negative electrodes.

[0051] Among them, the positive electrode shell, spring sheet, gasket, and negative electrode shell are all made of nickel-containing stainless steel material in existing technology.

[0052] The positive electrode sheet includes a current collector (aluminum foil), an active material (5,11-dihydroindolo[3,2-b]carbazole), a conductive agent (carbon nanotubes), and a binder (polyvinylidene fluoride, i.e., PVDF).

[0053] The electrolyte consists of a metal salt (lithium bis(trifluoromethanesulfonyl)imide, i.e., LiFSI) and an organic solvent (ethylene carbonate (EC) and dimethyl carbonate (DMC)). The concentration of the metal salt in the electrolyte is 5 mol / L.

[0054] The negative electrode is a lithium sheet;

[0055] The diaphragm is made of glass fiber.

[0056] The lithium-based dual-ion battery in this example was prepared using the following method, with the specific steps as follows:

[0057] (1) Preparation of positive electrode sheet: The active material (5,11-dihydroindodo[3,2-b]carbazole), carbon nanotubes and PVDF are mixed in a certain proportion (60% by mass of 5,11-dihydroindodo[3,2-b]carbazole, 30% by mass of carbon nanotubes and 10% by mass of PVDF), N-methylpyrrolidone is added, and the mixture is ground evenly to obtain a slurry. The slurry is then evenly coated onto the aluminum foil of the positive electrode current collector and placed in a vacuum drying oven. The dried positive electrode sheet is then cut into circular electrode sheets with a diameter of 10 mm for later use.

[0058] (2) Preparation of negative electrode sheet: Cut the lithium metal sheet into a circular electrode sheet with a diameter of 12mm and set aside.

[0059] (3) Preparation of diaphragm: Glass fiber diaphragm is used. It is cut into round pieces with a diameter of 16mm and dried in an oven for later use.

[0060] (4) Prepare electrolyte: Weigh 3.74g of LiFSI and add it to a mixture of 2mL EC and 2mL DMC. Stir until dissolved to obtain a 5mol / L LiFSI-EC-DMC electrolyte for later use.

[0061] (5) Battery assembly: In a glove box filled with argon gas and containing oxygen and water content ≤0.1ppm, the positive electrode shell, a 19mm diameter aluminum foil anti-corrosion layer (to prevent FSI) are sequentially assembled. - The battery casing and current collector (which are corroded by salt), positive electrode, and separator are stacked together, then filled with electrolyte. Then, negative electrode, spring sheet, gasket, and negative electrode casing are stacked on the separator in sequence, and finally packaged to obtain a dual-ion battery.

[0062] (6) In-situ electropolymerization process: The lithium-based dual-ion battery obtained in step (5) is charged and discharged 7 times at a rate of 50mA / g in the voltage range of 1.8-4.6V to fully form the positive electrode material of in-situ electropolymerization, thus obtaining the lithium-based dual-ion battery in this example.

[0063] The dual-ion battery prepared in step (5) was subjected to eight complete charge-discharge cycles at a rate of 50 mA / g within a voltage range of 1.8–4.6 V. The infrared spectra of the lithium-based dual-ion battery at different charging voltages were then measured. Specific test results are as follows: Figure 1 As shown, the CV curves of the lithium-based dual-ion battery at different cycling counts were then tested. Specific test results are as follows: Figure 2 As shown. By Figure 1 It can be seen that when 5,11-dihydroindolo[3,2-b]carbazole is charged to 4V, the infrared spectrum does not change significantly, but when charged to 4.6V, the infrared spectrum changes at 834cm⁻¹. 1The presence of absorption peaks at the 3-position indicates that the 1,2,4-trisubstituted benzene ring has undergone in-situ electropolymerization at the 3-position, proving that 5,11-dihydroindolo[3,2-b]carbazole has undergone in-situ electropolymerization. Figure 2 It can be seen that during the electropolymerization process, the oxidation peak at ~4.1V of 5,11-dihydroindodo[3,2-b]carbazole gradually disappears. The cycle curves of the 7th and 8th cycles basically overlap, indicating that the 5,11-dihydroindodo[3,2-b]carbazole material has been completely polymerized by the 7th cycle. Therefore, the optimal number of polymerization cycles is 7.

[0064] SEM images of the positive electrode and the positive electrode after electropolymerization were obtained using scanning electron microscopy. Specific test results are as follows: Figure 3 As shown, where, Figure 3 (a) and Figure 3 (b) SEM images of the positive electrode before and after electropolymerization, respectively. Figure 3 It can be seen that the positive electrode sheet is a bulk structure before electropolymerization, while after the electropolymerization reaction, the positive electrode sheet is electropolymerized in situ into a nanowire structure.

[0065] The lithium-based dual-ion battery in this example was tested for its charge-discharge performance at a rate of 100 mA / g within a voltage range of 1.8-4.5V for 300 cycles. The specific test results are as follows: Figure 4 and Figure 5 As shown, where, Figure 4 This is a charge / discharge curve of the lithium-based dual-ion battery in this example. Figure 5 This is a cycle capacity curve for the lithium-based dual-ion battery in this example. Figure 4 As can be seen, the lithium-based dual-ion battery in this example exhibits a relatively high discharge specific capacity of 186 mAh / g. From Figure 5 As can be seen, the lithium-based dual-ion battery in this example exhibits typical charge-discharge cycle performance, with virtually no capacity decay during 300 cycles, and also demonstrates a coulombic efficiency close to 100%, further indicating that the lithium-based dual-ion battery using polymeric organic materials exhibits excellent long-cycle stability.

[0066] Example 2-15

[0067] The lithium-based dual-ion batteries in Examples 2-15 have the same battery structure and electrolyte as those in Example 1. The only difference between Examples 2-15 and Example 1 is the type of active material in the positive electrode. The types of active materials in Examples 2-15 are shown in Table 1.

[0068] The lithium-based dual-ion batteries in Examples 2-15 were prepared using the same method as the battery in Example 1.

[0069] The lithium-based dual-ion batteries in Examples 1-15 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 1.

[0070] Table 1: Types and performance test results of active materials in lithium-based dual-ion batteries in Examples 1-15

[0071]

[0072]

[0073] As shown in Table 1, compared with Examples 2-15, Example 1, using 5,11-dihydroindolo[3,2-b]carbazole as the active material, exhibits superior specific capacity and cycle stability. This may be because 5,11-dihydroindolo[3,2-b]carbazole possesses excellent molecular symmetry, resulting in less steric hindrance during anion storage and better electrochemical energy storage performance.

[0074] Examples 16-19

[0075] The lithium-based dual-ion batteries in Examples 16-19 have the same battery structure and electrolyte as the battery in Example 1. The only difference between Examples 16-19 and Example 1 is the type of conductive agent used. The types of conductive agents used in Examples 16-19 are recorded in Table 2.

[0076] The lithium-based dual-ion batteries in Examples 16-19 were prepared using the same method as the battery in Example 1.

[0077] The lithium-based dual-ion batteries in Examples 16-19 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 2.

[0078] Table 2: Types and performance test results of conductive agents in lithium-based dual-ion batteries in Examples 16-19

[0079] Example 1 carbon nanotubes 186 844 Example 16 Acetylene black 153 635 Example 17 graphene 170 731 Example 18 Super-P 183 830 Example 19 carbon nanofibers 173 678

[0080] As shown in Table 2, compared with Examples 16-19, the lithium-based dual-ion battery prepared in Example 1 using carbon nanotubes as a conductive agent has a higher specific capacity and a higher number of cycles when the capacity is maintained at around 80%, indicating better secondary battery performance.

[0081] Examples 20-25

[0082] The lithium-based dual-ion batteries in Examples 20-25 have the same battery structure and electrolyte as the battery in Example 1. The only difference between Examples 20-25 and Example 1 is the type of binder used. The types of binders used in Examples 20-25 are recorded in Table 3.

[0083] The lithium-based dual-ion batteries in Examples 20-25 were prepared using the same method as the battery in Example 1.

[0084] The lithium-based dual-ion batteries in Examples 20-25 were tested for charge-discharge performance at a rate of 100 mA / g within a voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 3.

[0085] Table 3: Types and performance test results of binders for lithium-based dual-ion batteries in Examples 20-25

[0086] Example 1 polyvinylidene fluoride 186 844 Example 20 polytetrafluoroethylene 176 735 Example 21 Sodium carboxymethyl cellulose 181 569 Example 22 Carboxylated styrene-butadiene latex 168 538 Example 23 Polyvinyl alcohol 173 567 Example 24 Sodium alginate 169 757 Example 25 polyurethane 173 583

[0087] As shown in Table 3, compared with Examples 20-25, the lithium-based dual-ion battery prepared by using polyvinylidene fluoride as a binder in Example 1 has improved specific capacity and cycle performance, but the increase in specific capacity is not significant, while the increase in cycle performance is significant.

[0088] Examples 26-32

[0089] The lithium-based dual-ion batteries in Examples 26-32 have the same battery structure and electrolyte as the battery in Example 1. The only difference between Examples 26-32 and Example 1 is the type of separator used. The types of separators used in Examples 26-32 are recorded in Table 4.

[0090] The lithium-based dual-ion batteries in Examples 26-32 were prepared using the same method as the battery in Example 1.

[0091] The lithium-based dual-ion batteries in Examples 26-32 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 4.

[0092] Table 4: Types and performance test results of separators for lithium-based dual-ion batteries in Examples 26-32

[0093]

[0094]

[0095] As shown in Table 4, the performance of the lithium-based dual-ion battery in this invention is greatly affected by the type of separator, and the battery using glass fiber membrane and porous polyethylene-polypropylene composite film as separator has better performance than the battery using other materials as separator.

[0096] Examples 33-42

[0097] The lithium-based dual-ion batteries in Examples 33-42 have the same battery structure and electrolyte as the battery in Example 1. The only difference between Examples 33-42 and Example 1 is the type of positive electrode current collector. The types of positive electrode current collectors used in Examples 33-42 are recorded in Table 5.

[0098] The lithium-based dual-ion batteries in Examples 33-42 were prepared by the same method as the battery in Example 1.

[0099] The lithium-based dual-ion batteries in Examples 33-42 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 5.

[0100] Table 5: Types and performance test results of positive electrode current collectors for lithium-based dual-ion batteries in Examples 33-42

[0101]

[0102]

[0103] As shown in Table 5, the lithium-based dual-ion battery of the present invention has better performance than the battery using aluminum, nickel-titanium alloy, nickel, titanium, and nickel-manganese alloy as the positive electrode current collector.

[0104] Examples 43-70

[0105] The lithium-based dual-ion batteries in Examples 43-70 have the same battery structure as the battery in Example 1. The only difference between Examples 43-70 and Example 1 is the type of organic solvent in the electrolyte. The types of organic solvents used in the electrolytes of Examples 43-70 are recorded in Table 6.

[0106] The lithium-based dual-ion batteries in Examples 43-70 were prepared using the same method as the battery in Example 1.

[0107] The lithium-based dual-ion batteries in Examples 43-70 were tested for charge and discharge performance at a rate of 100 mA / g in a voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 6.

[0108] Table 6: Types and performance test results of organic solvents in the electrolytes of lithium-based dual-ion batteries in Examples 43-70

[0109]

[0110]

[0111] As shown in Table 6, when EC+DMC (v / v 1:1) is used as the organic solvent in the electrolyte, the specific capacity and cycle stability of the lithium-based dual-ion battery are better than those of the battery using other organic solvents. This indicates that EC+DMC (v / v 1:1) is more conducive to the in-situ electropolymerization of organic matter when used as the organic solvent in the electrolyte.

[0112] Examples 71-75

[0113] The lithium-based dual-ion batteries in Examples 71-75 have the same battery structure and electrolyte type as the battery in Example 1. The only difference between Examples 71-75 and Example 1 is the concentration of the electrolyte. The concentrations of the electrolytes used in Examples 71-75 are recorded in Table 7.

[0114] The lithium-based dual-ion batteries in Examples 71-75 were prepared using the same method as the battery in Example 1.

[0115] The lithium-based dual-ion batteries in Examples 71-75 were tested for charge and discharge performance at a rate of 100 mA / g in a voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 7.

[0116] Table 7: Electrolyte Concentration and Performance Test Results of Lithium-Based Dual-Ion Batteries in Examples 71-75

[0117] Example 1 5mol / L LiFSI / EC-DMC 186 844 Example 71 1mol / L LiFSI / EC-DMC 153 664 Example 72 2mol / L LiFSI / EC-DMC 162 684 Example 73 3mol / L LiFSI / EC-DMC 177 754 Example 74 4mol / L LiFSI / EC-DMC 184 806 Example 75 6.6 mol / L LiFSI / EC-DMC 173 831

[0118] As shown in Table 7, the specific capacity and cycle performance of the lithium-based dual-ion battery in this invention initially increase slowly with increasing electrolyte concentration. The optimal specific capacity and cycle performance are achieved when the electrolyte concentration is around 5 mol / L. Subsequently, the specific capacity and cycle performance decrease slowly with further increases in electrolyte concentration. The lithium-based dual-ion battery exhibits higher specific capacity and cycle stability at higher electrolyte concentrations, primarily because higher electrolyte concentrations are more conducive to the in-situ electropolymerization process. However, excessively high electrolyte concentrations may lead to excessively high electrolyte viscosity, which reduces ion migration performance, resulting in a decrease in both capacity and long-term cycle performance. Therefore, a higher electrolyte concentration is not necessarily better.

[0119] Examples 76-80

[0120] The lithium-based dual-ion batteries in Examples 76-80 have the same battery structure as the battery in Example 1. The only differences between Examples 76-80 and Example 1 are: different negative electrode materials and / or different types of electrolytes in the electrolyte. Specifically, Examples 76-77 changed the negative electrode material, and Examples 78-80 changed the FSI-metal salt in Examples 1, 76, and 77 to TFSI-metal salt, respectively. The negative electrode materials and electrolytes used in Examples 76-80 are recorded in Table 8.

[0121] The lithium-based dual-ion batteries in Examples 76-80 were prepared using the same method as the battery in Example 1.

[0122] The lithium-based dual-ion batteries in Examples 76-80 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 8.

[0123] Table 8: Anode material, electrolyte, and performance test results of lithium-based dual-ion batteries in Examples 76-80

[0124]

[0125]

[0126] As shown in Table 8, among the different metal-based dual-ion batteries tested, the battery with lithium foil as the negative electrode material and 5 mol / L LiFSI / EC-DMC as the electrolyte has better specific capacity and long cycle performance. This is mainly because the deposition / desorption behavior of lithium ions at the negative electrode is faster than that of sodium and potassium ions. At the same time, FSI-salt is more conducive to the in-situ electropolymerization process of organic cathode than TFSI-salt.

[0127] Examples 81-89

[0128] The lithium-based dual-ion batteries in Examples 81-89 are the same as those in Example 1. The only difference between Examples 81-89 and Example 1 is that the voltage range selected in the polymerization process is different. The specific voltage range is recorded in Table 9.

[0129] The lithium-based dual-ion batteries in Examples 81-89 were tested for charge and discharge performance at a rate of 100 mA / g in the voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 9.

[0130] Table 9: Voltage range and performance test results of the lithium-based dual-ion battery polymerization process in Examples 81-89

[0131]

[0132] As shown in Table 9, compared with the voltage range of other polymerization processes, the lithium-based dual-ion battery obtained by electropolymerization reaction at 1.8V-4.6V has better specific capacity and cycle stability. This is because the in-situ electropolymerization effect of active material is better in the voltage range of 1.8V-4.6V. Too high a voltage may lead to the decomposition of active material and electrolyte, while too low a voltage may lead to incomplete polymerization. Therefore, both too high and too low polymerization voltage will lead to a decrease in battery specific capacity and cycle performance.

[0133] Examples 90-95

[0134] The lithium-based dual-ion batteries in Examples 90-95 are the same as those in Example 1. The only difference between Examples 90-95 and Example 1 is that the polymerization rate selected is different (1C = 100mA / g). The specific polymerization rate data is recorded in Table 10.

[0135] The lithium-based dual-ion batteries in Examples 90-95 were tested for charge and discharge performance at a rate of 100 mA / g in a voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 10.

[0136] Table 10: Rate and performance test results of the lithium-based dual-ion battery polymerization process in Examples 90-95

[0137]

[0138] As can be seen from Table 10, using a rate of 0.5C during electropolymerization can improve the specific capacity and cycle stability of lithium-based dual-ion batteries. This indicates that the polymerization product obtained by polymerizing the active material at a rate of 0.5C has the best effect. Too high a rate may result in incomplete polymerization, and the active material will still dissolve, leading to low capacity and poor cycle stability. Too low a rate will result in more electrolyte decomposition byproducts and complex polymerization products, resulting in low capacity and poor cycle performance.

[0139] Examples 96-101

[0140] The lithium-based dual-ion batteries in Examples 96-101 are the same as those in Example 1. The only difference between Examples 96-101 and Example 1 is that the number of charge-discharge cycles in the polymerization process is different. The specific number of charge-discharge cycles in the polymerization process is recorded in Table 11.

[0141] The lithium-based dual-ion batteries in Examples 96-101 were tested for charge-discharge performance at a rate of 100 mA / g in a voltage range of 1.8-4.5V. The specific capacity data and the number of cycles when the capacity retention rate reached about 80% were recorded in Table 11.

[0142] Table 11: Charge-discharge cycle count and performance test results of lithium-based dual-ion battery polymerization process in Examples 96-101

[0143]

[0144]

[0145] As shown in Table 11, the battery exhibits better specific capacity and cycle stability when the polymerization process is controlled to 7 cycles. This is because the degree of polymerization of the active material is ideal after 7 cycles. If the number of polymerization cycles is too small, the active material will not polymerize completely, resulting in lower specific capacity and poorer cycle stability. The polymerization voltage is higher than the normal charge and discharge voltage. Too many polymerization cycles can lead to the decomposition of the active material and electrolyte, which is detrimental to the formation of electropolymerization products and thus reduces battery performance.

[0146] In summary, compared with existing dual-ion batteries, the dual-ion battery of this invention has the following advantages:

[0147] (1) In the present invention, the positive and negative electrodes of the dual-ion battery store anions and cations respectively during operation. The insertion / extraction of large-sized anions results in a higher operating voltage, which improves the battery's energy density and power density.

[0148] (2) The active material in this invention has the characteristics of wide availability of raw materials, low cost, and designable and diverse molecular energy storage sites, which can effectively reduce the cost of batteries.

[0149] (3) The active material in this invention will undergo in-situ electropolymerization during charging under specific high-concentration electrolyte (around 5 mol / L), specific rate (around 0.5C), and high voltage (1.5-5V). This not only effectively alleviates the dissolution of electrode materials and improves the cycle stability of the battery, but also increases the theoretical specific capacity of a single active site and improves the energy storage capacity through in-situ electropolymerization, ultimately achieving the goal of stable high-capacity energy storage.

[0150] (4) The active material in this invention is polymerized by in-situ electropolymerization, which has the advantages of simple operation and significant effect.

[0151] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A dual-ion battery, characterized in that: Includes a positive electrode; the positive electrode includes a positive electrode material layer, the positive electrode material layer comprising a polymer generated by in-situ electropolymerization of an active material; the active material is 5,11-dihydroindolo[3,2-b]carbazole; The positive electrode material layer also includes a conductive agent and a binder; The conductive agent is selected from at least one of conductive carbon black, graphene, and carbon nanotubes; The adhesive is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, and sodium alginate; The positive electrode also includes a current collector; the positive electrode material layer is disposed on the current collector; The current collector is selected from elemental metals or metal alloys; the elemental metal is selected from at least one of aluminum, titanium, and nickel; the metal alloy is selected from at least one of nickel-titanium alloys and nickel-manganese alloys. The battery also includes a negative electrode, an electrolyte, and a separator; the negative electrode is made of lithium, sodium, or potassium. The electrolyte comprises a metal salt and an organic solvent; the organic solvent is a mixed solvent of ethylene carbonate and dimethyl carbonate, a mixed solvent of propylene carbonate and ethylene carbonate, or the organic solvent is selected from at least one of dimethyl carbonate, fluoroethylene carbonate, and dimethyl sulfoxide. The voltage of the in-situ electropolymerization reaction is 1.8-4.6V, the rate of the in-situ electropolymerization reaction is 45-55mA / g, and the number of cycles is 7-9.

2. The dual-ion battery according to claim 1, characterized in that: The mass ratio of the active material, conductive agent, and binder is (5~7):(2~4):

1.

3. The dual-ion battery according to claim 1, characterized in that: The diaphragm is located between the positive and negative electrodes; the space between the positive and negative electrodes is filled with electrolyte.

4. The dual-ion battery according to claim 1, characterized in that: The concentration of the metal salt is 1~7 mol / L.

5. The dual-ion battery according to claim 1, characterized in that: The metal salt is selected from at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, potassium bis(fluorosulfonyl)imide, and potassium bis(trifluoromethanesulfonyl)imide.

6. The dual-ion battery according to claim 1, characterized in that: The diaphragm is selected from at least one of polyethylene film, polypropylene film, cellulose composite film, glass fiber film, polyvinylidene fluoride film, nonwoven fabric, alumina ceramic diaphragm, and polyethylene-polypropylene composite film.

7. The method for preparing a dual-ion battery according to any one of claims 1 to 6, characterized in that: Includes the following steps: The positive electrode, negative electrode, separator, and electrolyte are assembled into a battery, and the active material is then subjected to an in-situ electropolymerization reaction to obtain the dual-ion battery. The in-situ electropolymerization reaction has a rate of 45~55 mA / g and a cycle count of 7~9 times.

8. The application of the dual-ion battery according to any one of claims 1 to 6 in electronic products or new energy transportation equipment.

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