A biphenylamine lithium compound, a preparation method thereof and application thereof in lithium ion batteries

Abstract

The present application relates to a kind of diphenylamine lithium compound and its preparation method and application in lithium ion battery, the diphenylamine lithium compound can be used as redox active species for lithium ion battery positive electrode material.Due to the diphenylamine lithium compound has the characteristics such as high redox potential, stable, etc., with it as positive active material lithium ion half battery has higher voltage platform and better charge-discharge cycle stability.

Description

Technical Field

[0001] This invention belongs to the fields of electrochemistry and energy storage, specifically relating to a benzidine-based lithium compound, its preparation method, and its application in lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries, with their high energy and power density, are widely used in portable electronics, electric vehicles, and aerospace. Traditional lithium-ion battery cathode active materials utilize lithium-containing inorganic metal oxides or phosphates, whose sources are limited by mineral resources. Furthermore, inorganic materials are inherently rigid, and their structure is susceptible to changes during lithium-ion insertion / extraction, leading to performance degradation or failure. The use of organic molecules as redox active components in cathode materials has garnered significant attention from researchers. Organic molecules are abundant and diverse, and their electrochemical properties can be modified through functional group modification.

[0003] Currently, there are not many types of organic cathode active materials, mainly carbonyl-containing conjugated materials, which generally have low redox potentials, greatly limiting the energy density of organic lithium-ion batteries. Therefore, designing and developing organic cathode materials with high redox potentials and good stability is of great significance. Summary of the Invention

[0004] According to one aspect of this application, a compound is provided having the structure shown in Formula I:

[0005]

[0006]

[0007] In the compound, the two substituents R1 on the N atom are selected from one of formyl, acetyl, methanesulfonyl, ethanesulfonyl, benzenesulfonyl, or cyano.

[0008] The substituent R1 on the N atom in the compound must be an electron-withdrawing substituent. On the one hand, it can disperse the concentrated negative charge on the N atom in the molecule, making the molecule more stable. On the other hand, it can also increase the redox potential of the molecule.

[0009] The substituent R at the adjacent position of the N atom in the compound 21 R 22 R 23 R 24 It is independently selected from one of H, F, Cl, Br, methyl, ethyl, methoxy, methoxycarbonyl, ethoxycarbonyl or nitro;

[0010] The substituent R at the meta position of the N atom in the compound 31 R 32 R33 R 34 It is independently selected from one of H, F, Cl, Br, methyl, ethyl, methoxy, methoxycarbonyl, ethoxycarbonyl or nitro.

[0011] The redox potential of the compound is also affected by the substituents R on the ortho and meta positions of the N atom in its structure. 21 R 22 R 23 R 24 R 31 R 32 R 33 R 34 The influence of H. Using H as the substituent standard, its characteristics are as follows:

[0012] When the substituents are selected from electron-donating groups such as methyl or methoxy, their effect is to reduce the redox potential of the benzidine-based lithium compound, and the extent of the reduction is determined by the type and number of the specific substituents; when the substituents are selected from electron-withdrawing groups such as F, Cl or Br, their effect is to increase the redox potential of the benzidine-based lithium compound, and the extent of the increase is determined by the type and number of the specific substituents.

[0013] According to another aspect of this application, a method for preparing the above-mentioned compound is provided, comprising the following steps:

[0014] 1) The acyl chloride substrate was mixed with a dichloromethane solution containing benzidine substrate and base, reacted, extracted, and dried to obtain the sulfonamide intermediate;

[0015] 2) Dissolve the sulfonamide intermediate obtained in 1) in dichloromethane, mix with LiH under an inactive gas atmosphere, filter, and dry to obtain the compound.

[0016] The benzidine substrate includes benzidine and / or benzidine derivatives;

[0017] Optionally, the benzidine derivative includes at least one selected from 2,2'-difluorobenzidine, 2,2'-dichlorobenzidine, 2,2'-dibromobenzidine, 2,2'-dimethylbenzidine, 2,2'-diethylbenzidine, 2,2'-dimethoxybenzidine, 2,2'-dimethoxycarbonylbenzidine, 2,2'-diethoxycarbonylbenzidine, 2,2'-dinitrobenzidine, 3,3'-difluorobenzidine, 3,3'-dichlorobenzidine, 3,3'-dibromobenzidine, 3,3'-dimethylbenzidine, 3,3'-diethylbenzidine, 3,3'-dimethoxycarbonylbenzidine, 3,3'-diethoxycarbonylbenzidine, and 3,3'-dinitrobenzidine.

[0018] The acyl chloride substrate includes at least one of methanesulfonyl chloride, acetyl chloride, benzenesulfonyl chloride, propionyl chloride, and p-toluenesulfonyl chloride;

[0019] The alkali includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, quinine ring, and triethylamine;

[0020] In the dichloromethane solution containing benzidine substrate and base, the concentration of benzidine substrate is 0.1–10 mmol / ml;

[0021] In the dichloromethane solution containing benzidine substrate and base, the molar ratio of benzidine substrate to base is 1:1 to 1:5;

[0022] The molar ratio of the acyl chloride substrate to the benzidine substrate in the dichloromethane solution is 1:1 to 5:1.

[0023] The molar ratio of the sulfonamide intermediate to the LiH is 1:1 to 1:5;

[0024] The inactive gas atmosphere includes at least one of nitrogen, helium, and argon.

[0025] According to another aspect of this application, a cathode material is provided, the cathode material comprising the above-described compound or a compound prepared by the above-described preparation method, as a redox active species.

[0026] According to another aspect of this application, a lithium-ion battery is provided, the lithium-ion battery including a positive electrode;

[0027] The positive electrode material includes the aforementioned positive electrode material.

[0028] The lithium-ion battery has a high voltage platform and good charge-discharge cycle stability.

[0029] The average discharge voltage of the lithium-ion battery is 3.45–3.82V;

[0030] The capacity retention rate of the lithium-ion battery after 50 charge-discharge cycles is 76.5% to 88.2%.

[0031] The compound, as a redox active species in the positive electrode material of lithium-ion batteries, undergoes the following redox process on the electrode:

[0032]

[0033] The lithium-ion battery is obtained according to the following preparation method:

[0034] a) The compound, conductive agent, and binder are mixed and then uniformly dispersed in a dispersant to obtain slurry A;

[0035] b) Coat the slurry A obtained in step a) evenly onto the current collector, dry it, and then cut it into a positive electrode sheet;

[0036] c) Separate the positive electrode and lithium sheet obtained in step b) with a membrane impregnated with electrolyte, and then encapsulate them into a coin cell in a glove box.

[0037] The conductive agent mentioned in step a) is selected from one or more of acetylene black, Super P, Ketjen black (KB) or conductive graphite;

[0038] Preferably, the conductive agent in step a) is selected from Super P or Ketjen Black;

[0039] The adhesive mentioned in step a) is polyvinylidene fluoride (PVDF);

[0040] The dispersant mentioned in step a) is N-methylpyrrolidone (NMP);

[0041] The current collector mentioned in step b) is aluminum foil;

[0042] The electrolyte in step c) is a lithium salt solution, wherein the lithium salt is selected from one or more of LiBF4, LiPF6, LiFSI or LiTFSI;

[0043] Preferably, the lithium salt in step c) is selected from either LiTFSI or LiFSI;

[0044] The solvent of the electrolyte in step c) is selected from one or more of dimethyl carbonate, ethylene carbonate, diethyl carbonate, or ethylene glycol dimethyl ether.

[0045] Preferably, the solvent of the electrolyte in step c) is selected from dimethyl carbonate or diethyl carbonate;

[0046] The diaphragm mentioned in step c) is a polypropylene film;

[0047] The mass ratio of the benzidine-based lithium compound to the adhesive in step a) is 50–90:1;

[0048] Preferably, the mass ratio of the benzidine-based lithium compound to the adhesive in step a) is 80–90:1;

[0049] The mass ratio of the conductive agent to the adhesive in step a) is 5 to 30:1;

[0050] Preferably, the mass ratio of the conductive agent to the adhesive in step a) is 15 to 20:1;

[0051] The mass ratio of the dispersant and the binder in step a) is 5 to 50:1;

[0052] Preferably, the mass ratio of the dispersant to the binder in step a) is 20–25:1;

[0053] The coating thickness of slurry A on the current collector in step b) is 1-2 mm;

[0054] The concentration of the electrolyte mentioned in step c) is 1–3 mol / L;

[0055] The drying temperature described in step b) is 40–100°C, and the drying time is 1–24 h;

[0056] Preferably, the drying temperature in step b) is 60–80°C, and the drying time is 8–12 h.

[0057] In the above-mentioned method for preparing lithium-ion batteries:

[0058] The type and content of the benzidine-based lithium compounds, conductive agents, and binders in slurry A described in step a) will affect the charge / discharge capacity and internal resistance of the lithium-ion battery: the content of benzidine-based lithium compounds affects the charge / discharge capacity of the battery, and a higher content results in a higher battery capacity; the content of conductive agents affects the conductivity of the positive electrode material, thereby affecting the battery's internal resistance, and a higher content results in stronger conductivity of the positive electrode material and lower battery internal resistance; the content of binders affects the connection between the benzidine-based lithium compounds, conductive agents, and electrode current collectors, and a lower content results in poor adhesion, making it easier for the benzidine-based lithium compounds to peel off from the positive electrode, leading to capacity decay, while a higher content results in stronger adhesion, but the insulating properties of the binders will increase the battery's internal resistance.

[0059] Because the benzidine-based lithium compounds have high redox potential and good stability, lithium-ion half-cells using them as positive electrode active materials have a high voltage plateau and good charge-discharge cycle stability.

[0060] Compared with the prior art, the benzidine-based lithium compounds and their application in lithium-ion batteries provided by the present invention have the following advantages:

[0061] 1) The benzidine-based lithium compounds are easy to synthesize, have high reaction product yields, and low preparation costs;

[0062] 2) The redox potential of the benzidine-based lithium compound is adjustable, and as a positive electrode redox species of lithium-ion batteries, it can achieve a larger battery voltage.

[0063] 3) The benzidine-based lithium compounds have good charge and discharge stability, and as positive electrode redox species of lithium-ion batteries, they can enable long-cycle operation of the batteries. Attached Figure Description

[0064] Figure 1The 1H NMR spectrum of N,N'-dimethylsulfonylbenzidine lithium obtained in Example 1 ( 1 H-NMR results.

[0065] Figure 2 This is the first charge-discharge curve of half-cell A-1 in Example 3, using N,N'-dimethylsulfonylbenzidine-lithium as the redox active species. The test was conducted using NEWARE battery testing equipment from Newwell Electronics Co., Ltd., under the following conditions: charging cutoff voltage 4.0V, discharging cutoff voltage 2.8V, and charge / discharge rate 0.1C.

[0066] Figure 3 This refers to the discharge specific capacity of half-cell A-1 in Example 7, which uses N,N'-dimethylsulfonylbenzidine-lithium as the redox active species, at different charge-discharge rates. The tests were conducted using NEWARE battery testing equipment from Newwell Electronics Co., Ltd., under the following conditions: charging cutoff voltage 4.0V, discharging cutoff voltage 2.8V, and 5 charge-discharge cycles each at charge-discharge rates of 0.1C, 0.5C, and 1.0C. Detailed Implementation

[0067] To further illustrate the present invention, the following embodiments are provided based on experimental results and in conjunction with the accompanying drawings, but these embodiments do not limit the scope of the invention as defined by the claims.

[0068] Example 1

[0069] This embodiment illustrates the preparation of the benzidine-based lithium compound.

[0070] 1) Weigh 10 mmol of benzidine substrate (both amino groups are in the para position) and 30 mmol of triethylamine and dissolve them in 20 mL of dry dichloromethane. Cool to 0 °C and stir for 15 min.

[0071] 2) Add 24 mmol of acyl chloride substrate to the reaction solution and stir at room temperature for 12 h;

[0072] 3) After the reaction is complete, water is added to quench the reaction, and then the product is extracted with dichloromethane. The obtained organic phase is dried with anhydrous sodium sulfate and the solvent is evaporated to obtain the sulfonamide intermediate.

[0073] 4) The sulfonamide intermediate obtained in 3) was dissolved in 20 mL of dry dichloromethane. Under nitrogen protection, 20 mmol of LiH was added, and the mixture was stirred at room temperature for 12 h. Finally, the mixture was filtered and dried to obtain the benzidine-based lithium compound. The product structure was determined by… 1 H-NMR confirmed (taking N,N'-dimethylsulfonylbenzidine lithium as an example) its 1 H-NMR results are as follows Figure 1 (As shown).

[0074] The benzidine substrate, acyl chloride substrate, corresponding products, and their yields used in the above preparation method are shown in the table below:

[0075]

[0076] DD220961I-DL

[0077]

[0078] Example 2

[0079] This embodiment illustrates the preparation of a lithium-ion half-cell using the aforementioned benzidine-based lithium compound as the positive electrode redox active material.

[0080] 140 mg of the aforementioned benzidine-based lithium compound, 26.25 mg of KB, and 1.75 mg of PVDF (mass ratio 80:15:1) were weighed and mixed uniformly. This mixture was then uniformly dispersed in 35 mg of NMP (mass ratio of NMP to PVDF was 20:1) to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm and then dried in a vacuum drying oven at 60°C for 12 h. The resulting slurry was then cut into positive electrode sheets. The obtained positive electrode sheets and lithium sheets were separated by a polypropylene membrane impregnated with a 1 mol / L LiTFSI diethyl carbonate solution and encapsulated together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax and the aforementioned benzidine-based lithium compound is as follows:

[0081] A-1: N,N'-Dimethylsulfonylbenzidine lithium;

[0082] A-2: N,N'-Diacetylbenzidine lithium;

[0083] A-3: N,N'-Diphenylsulfonylbenzidine-lithium;

[0084] A-4: N,N'-dimethylsulfonyl-3,3'-difluorobenzidine-lithium;

[0085] A-5: N,N'-dimethylsulfonyl-3,3'-dichlorobenzidine lithium;

[0086] A-6: N,N'-dimethylsulfonyl-3,3'-dimethoxybenzidine lithium;

[0087] A-7: N,N'-Dimethylsulfonyl-2,2'-difluorobenzidine-lithium;

[0088] A-8: N,N'-dimethylsulfonyl-2,2'-dichlorobenzidine lithium;

[0089] A-9: Take N,N'-dimethylsulfonyl-2,2'-dimethylbenzidine lithium.

[0090] Comparative Example 1

[0091] This comparative example illustrates the preparation of a lithium-ion half-cell using N,N'-dimethylsulfonyl-2,2'-diphenylbenzidine lithium as the positive electrode redox active material, serving as a comparison for Examples 2 to 10.

[0092] Except that 140 mg of N,N'-dimethylsulfonyl-2,2'-diphenylbenzidine lithium was used instead of the 140 mg of N,N'-dimethylsulfonylbenzidine lithium used in Example 2, a coin cell was prepared in the same manner as in Example 2, and this half-cell was designated B-1.

[0093] Example 3

[0094] This embodiment illustrates the charge-discharge performance test of the coin cells prepared in Example 2 and Comparative Example 1.

[0095] The coin cell half-cells A-1 to A-9 and B-1 prepared in Example 2 and Comparative Example 1 were subjected to charge-discharge tests using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge-discharge rate 0.1C. Taking half-cell A-1 as an example, its first charge-discharge curve is shown below. Figure 2 As shown. Record the average discharge voltage and discharge specific capacity of the first discharge, and the discharge specific capacity of the 50th discharge (based on the mass of the benzidine-based lithium compound), and calculate the capacity retention rate according to the following formula:

[0096] Capacity retention rate = (Specific capacity at nth discharge / Specific capacity at 1st discharge) × 100%

[0097] The results are shown in Table 1:

[0098] Table 1. Charge and discharge test results of half-cells A-1 to A-9 and B-1

[0099]

[0100] It can be seen that the type of benzidine-based lithium compound, which is the positive electrode active species, affects the average discharge voltage and discharge specific capacity of the half-cell: compared with half-cell B-1, the benzidine-based lithium compounds selected in half-cells A-1 to A-9 have higher redox potentials, so their corresponding half-cells have higher average discharge voltages; at the same time, since the substituents introduced in the benzidine-based lithium compounds selected in half-cells A-1 to A-9 have better stability, their corresponding half-cells have higher capacity retention after multiple charge-discharge cycles.

[0101] Example 4

[0102] This embodiment illustrates the preparation of a lithium-ion half-cell by selecting N,N'-dimethylsulfonylbenzidine lithium as the positive electrode redox active material and changing its mass ratio with PVDF.

[0103] A certain amount of N,N'-dimethylsulfonylbenzidine-based lithium, 26.25 mg KB, and 1.75 mg PVDF (the mass ratio of KB to PVDF is 15:1) were weighed and uniformly mixed. This mixture was then uniformly dispersed in 35 mg NMP (the mass ratio of NMP to PVDF is 20:1) to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm and then dried in a vacuum drying oven at 60°C for 12 hours. The resulting slurry was then cut into positive electrode sheets. The positive electrode sheets and lithium sheets were separated by a polypropylene membrane impregnated with a 1 mol / L LiTFSI diethyl carbonate solution and packaged together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax, the amount of N,N'-dimethylsulfonylbenzidine-based lithium, and the mass ratio of N,N'-dimethylsulfonylbenzidine-based lithium, KB, and PVDF is as follows:

[0104] A-10: 157.5mg, 90:15:1;

[0105] A-11: 87.5mg, 50:15:1.

[0106] Example 5

[0107] This embodiment illustrates the charge-discharge performance testing of lithium-ion half-cells with different mass ratios of N,N'-dimethylsulfonylbenzidine-based lithium to PVDF.

[0108] The coin cells A-1, A-10, and A-11 prepared in Examples 2 and 4 were tested using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge / discharge rate 0.1C. The initial charge and discharge specific capacities (based on the mass of the benzidine-based lithium compound) were recorded, and the results are shown in Table 2.

[0109] Table 2. Charge and discharge test results of half-cells A-1, A-10, and A-11

[0110]

[0111]

[0112] It can be seen that the mass ratio of the benzidine-based lithium compound to the binder PVDF affects the charge-discharge specific capacity of the half-cell: compared with half-cells A-1 and A-10, the amount of benzidine-based lithium compound used as the positive electrode active species in half-cell A-11 is too low, resulting in a shorter charge-discharge platform and a significant decrease in the charge-discharge specific capacity of the half-cell.

[0113] Example 6

[0114] This embodiment illustrates the preparation of a lithium-ion half-cell by selecting N,N'-dimethylsulfonylbenzidine lithium as the positive electrode redox active material and changing the mass ratio of KB to PVDF.

[0115] 140 mg of N,N'-dimethylsulfonylbenzidine-based lithium, a certain amount of KB, and 1.75 mg of PVDF (the mass ratio of N,N'-dimethylsulfonylbenzidine-based lithium to PVDF is 80:1) were weighed and mixed uniformly. This mixture was then uniformly dispersed in 35 mg of NMP (the mass ratio of NMP to PVDF is 20:1) to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm and then dried in a vacuum drying oven at 60°C for 12 h. The resulting slurry was then cut into positive electrode sheets. The positive electrode sheets and lithium sheets were separated by a polypropylene membrane impregnated with a 1 mol / L LiTFSI diethyl carbonate solution and packaged together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax, the amount of KB, and the mass ratio of N,N'-dimethylsulfonylbenzidine-based lithium, KB, and PVDF is as follows:

[0116] A-12: 35mg, 80:20:1;

[0117] A-13: 8.75mg, 80:5:1.

[0118] Example 7

[0119] This embodiment illustrates the charge-discharge performance test of lithium-ion half-cells with different KB to PVDF mass ratios.

[0120] The coin cell half-cells A-1, A-12, and A-13 prepared in Examples 2 and 6 were subjected to charge-discharge tests using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge / discharge rates of 0.1C, 0.5C, and 1.0C, respectively. Taking half-cell A-1 as an example, its discharge specific capacity at different rates is as follows: Figure 3 As shown in Table 3, the initial discharge specific capacity (based on the mass of the benzidine-based lithium compound) under different charge / discharge rates was recorded.

[0121] Table 3. Charge and discharge test results of half-cells A-1, A-12, and A-13

[0122]

[0123] It can be seen that the mass ratio of KB to PVDF affects the rate performance of the half-cell: compared with half-cells A-1 and A-12, the amount of KB in half-cell A-13 is too low, which causes the conductivity of the positive electrode material to decrease, resulting in a significant decrease in the rate performance of the half-cell.

[0124] Example 8

[0125] This embodiment illustrates the preparation of a lithium-ion half-cell by selecting N,N'-dimethylsulfonylbenzidine lithium as the positive electrode redox active material and changing the mass ratio of NMP to PVDF.

[0126] 140 mg of N,N'-dimethylsulfonylbenzidine lithium, 26.25 mg of KB, and 1.75 mg of PVDF (mass ratio 80:15:1) were weighed and uniformly mixed. This mixture was then uniformly dispersed in a certain amount of NMP to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm and then dried in a vacuum drying oven at 60°C for 12 h. The resulting slurry was then cut into positive electrode sheets. The obtained positive electrode sheets and lithium sheets were separated by a polypropylene membrane impregnated with a 1 mol / L LiTFSI diethyl carbonate solution and packaged together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax, the amount of NMP, and the mass ratio of NMP to PVDF is as follows:

[0127] A-14: 43.75mg, 25:1;

[0128] A-15: 87.5mg, 50:1;

[0129] A-16: 8.75mg, 5:1.

[0130] Example 9

[0131] This embodiment illustrates the charge-discharge performance testing of lithium-ion half-cells with different NMP to PVDF mass ratios.

[0132] The coin cells A-1, A-14 to A-16 prepared in Examples 2 and 8 were subjected to charge-discharge tests using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge-discharge rate 0.1C. The initial charge and discharge specific capacities (based on the mass of the benzidine-based lithium compound) were recorded, and the results are shown in Table 4.

[0133] Table 4. Charge and discharge test results of half-cells A-1, A-14 to A-16

[0134]

[0135] It can be seen that the mass ratio of dispersant NMP to binder PVDF affects the discharge specific capacity of the half cell: compared with examples A-1 and A-14, the excessive amount of NMP in A-15 resulted in a low concentration of active species, leading to a decrease in the charge-discharge specific capacity of the half cell; the insufficient amount of NMP in A-16 resulted in uneven dispersion of active species, which also led to a decrease in the charge-discharge specific capacity.

[0136] Example 10

[0137] This embodiment illustrates the preparation of lithium-ion half-cells using N,N'-dimethylsulfonylbenzidine lithium as the positive electrode redox active material and different coating drying temperatures and times.

[0138] 140 mg of the aforementioned benzidine-based lithium compound, 26.25 mg of KB, and 1.75 mg of PVDF (mass ratio 80:15:1) were weighed and uniformly mixed. This mixture was then uniformly dispersed in 35 mg of NMP (mass ratio of NMP to PVDF was 20:1) to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm, then dried in a vacuum drying oven. The foil was then cut to form a positive electrode sheet. The resulting positive electrode sheet and lithium sheet were separated by a polypropylene membrane impregnated with a 1 mol / L LiTFSI diethyl carbonate solution and encapsulated together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax and the coating drying temperature and time is as follows:

[0139] A-17: 70℃, 12h;

[0140] A-18: 80℃, 12h;

[0141] A-19: 40℃, 12h;

[0142] A-20: 100℃, 12h;

[0143] A-21: 60℃, 8h;

[0144] A-22: 60℃, 10h;

[0145] A-23: 60℃, 2h;

[0146] A-24: 60℃, 24h.

[0147] Example 11

[0148] This embodiment illustrates the charge-discharge performance test of lithium-ion half-cells with different coating drying temperatures and times.

[0149] The coin cells A-1, A-17 to A-24 prepared in Examples 2 and 10 were subjected to charge-discharge tests using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge-discharge rate 0.1C. The specific capacity of the first discharge and the specific capacity of the 50th discharge (based on the mass of the benzidine-based lithium compound) were recorded, and the capacity retention rate was calculated. The results are shown in Table 5.

[0150] Table 5. Charge and discharge test results of half-cells A-1, A-17 to A-24

[0151]

[0152]

[0153] It can be seen that the drying temperature and time of the coating affect the discharge specific capacity of the half-cell: compared with half-cells A-1, A-17 and A-18, the drying temperature used in A-19 is too low and the drying time used in A-23 is too short, resulting in an excessively high NMP content in the coating, which leads to a decrease in the discharge specific capacity of the battery; the drying temperature used in A-20 is too high and the drying time used in A-24 is too long, which makes the active material prone to deactivation, and also leads to a decrease in the discharge specific capacity of the battery after multiple charge and discharge cycles.

[0154] Example 12

[0155] This embodiment illustrates the preparation of lithium-ion half-cells using N,N'-dimethylsulfonylbenzidine lithium as the positive electrode redox active material and different electrolyte solutes and solvents.

[0156] 140 mg of N,N'-dimethylsulfonylbenzidine lithium, 26.25 mg of KB, and 1.75 mg of PVDF (mass ratio 80:15:1) were weighed and mixed uniformly. This mixture was then uniformly dispersed in 35 mg of NMP (mass ratio of NMP to PVDF was 20:1) to obtain slurry a. Slurry a was uniformly coated onto aluminum foil to a thickness of 1 mm and then dried in a vacuum drying oven at 60°C for 12 h. The resulting slurry was then cut into positive electrode sheets. The positive electrode sheets and lithium sheets were separated by a polypropylene membrane impregnated with 1 mol / L electrolyte and packaged together to form a 2016 type coin cell, denoted as Ax. The correspondence between the half-cell name Ax and the electrolyte solute and solvent is as follows:

[0157] A-25: LiFSI, diethyl carbonate;

[0158] A-26: LiBF4, diethyl carbonate;

[0159] A-27: LiTFSI, dimethyl carbonate;

[0160] A-28: LiTFSI, ethylene carbonate.

[0161] Example 13

[0162] This embodiment illustrates the charge-discharge performance testing of lithium-ion half-cells with different electrolyte solutes and solvents.

[0163] The coin cells A-1, A-25 to A-28 prepared in Examples 2 and 12 were subjected to charge-discharge tests using NEWARE battery testing equipment from Newwell Electronics Co., Ltd. The test conditions were: charging cut-off voltage 4.0V, discharging cut-off voltage 2.8V, and charge / discharge rates of 0.1C, 0.5C, and 1.0C, respectively. The initial discharge specific capacity (based on the mass of the benzidine-based lithium compound) under different charge / discharge rate conditions was recorded, and the results are shown in Table 6.

[0164] Table 6. Charge and discharge test results of half-cells A-1, A-25 to A-28

[0165]

[0166] It can be seen that the electrolyte composition affects the rate performance of the half-cell: compared with LiTFSI (A-1) and LiFSI (A-25), the rate performance of the half-cell using LiBF4 (A-26) as the electrolyte solute is significantly reduced; compared with diethyl carbonate (A-1) and dimethyl carbonate (A-27), the rate performance of the half-cell using ethylene carbonate (A-28) as the electrolyte solvent is also significantly reduced.

[0167] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A compound, characterized in that, The compound has the structure shown in Formula I: Formula I; R1 is selected from one of formyl, acetyl, methanesulfonyl, ethanesulfonyl, or benzenesulfonyl. R 21 R 22 R 23 R 24 It is independently selected from one of H, F, Cl, Br, methyl, ethyl, or methoxy; R 31 R 32 R 33 R 34 It is independently selected from one of H, F, Cl, Br, methyl, ethyl or methoxy.

2. A method for preparing the compound according to claim 1, characterized in that, Includes the following steps: 1) The acyl chloride substrate was mixed with a dichloromethane solution containing benzidine substrate and base, reacted, extracted, and dried to obtain the sulfonamide intermediate; 2) Dissolve the sulfonamide intermediate obtained in 1) in dichloromethane, mix it with LiH under an inactive gas atmosphere, and dry it to obtain the compound.

3. The preparation method according to claim 2, characterized in that, The benzidine substrate includes benzidine and / or benzidine derivatives; The benzidine derivative is selected from at least one of 2,2'-difluorobenzidine, 2,2'-dichlorobenzidine, 2,2'-dibromobenzidine, 2,2'-dimethylbenzidine, 2,2'-diethylbenzidine, 3,3'-difluorobenzidine, 3,3'-dichlorobenzidine, 3,3'-dibromobenzidine, 3,3'-dimethylbenzidine, and 3,3'-diethylbenzidine.

4. The preparation method according to claim 3, characterized in that, The acyl chloride substrate is selected from at least one of methanesulfonyl chloride, acetyl chloride, and benzenesulfonyl chloride; The base is selected from at least one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, quinine ring, and triethylamine; In the dichloromethane solution containing benzidine substrate and base, the concentration of benzidine substrate is 0.1~10 mmol / ml; In the dichloromethane solution containing benzidine substrate and base, the molar ratio of benzidine substrate to base is 1:1 to 1:5; The molar ratio of the acyl chloride substrate to the benzidine substrate in the dichloromethane solution containing benzidine substrate and alkali is 1:1 to 5:

1.

5. The preparation method according to claim 2, characterized in that, The molar ratio of the sulfonamide intermediate to the LiH is 1:1 to 1:5; The inactive gas atmosphere is selected from at least one of nitrogen, helium, and argon.

6. A positive electrode material, characterized in that, The cathode material includes the compound according to claim 1 or the compound prepared by the preparation method according to any one of claims 2 to 5.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode; The material of the positive electrode includes the positive electrode material of claim 6.

8. The lithium-ion battery according to claim 7, characterized in that, The average discharge voltage of the lithium-ion battery is 3.45~3.82V; The capacity retention rate of the lithium-ion battery after 50 charge-discharge cycles is 76.5% to 88.2%.

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