Lithium secondary battery with wide temperature range, high voltage and high rate and application thereof

Abstract

The invention provides a wide-temperature-range, high-voltage and high-rate lithium secondary battery and application thereof. The lithium secondary battery includes a negative electrode sheet; the negative plate comprises a negative current collector and a negative active layer arranged on at least one surface of the negative current collector; the negative electrode active layer comprises a negative electrode active material, a conductive agent, a thickening agent and a binder; the conductive agent is a manganese selenide / acidified carbon nanotube composite material prepared from raw materials including acidified carbon nanotubes and manganese selenide. In the lithium secondary battery, the manganese selenide / acidified carbon nanotube composite material in the negative electrode can enhance the conductivity of the electrode material, and the electrolyte can be compatible with high voltage and wide temperature range, so that the high-rate discharge performance and high-low temperature cycle performance of the lithium secondary battery in the voltage test range of 2.75-4.8 V are improved, and the service life of the battery is prolonged; and the application requirements on high voltage, wide temperature range and high magnification in the market can be met.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology and relates to a lithium secondary battery, and in particular to a lithium secondary battery with a wide temperature range, high voltage, and high rate and its application. Background Art

[0002] As the global energy mix shifts toward renewable energy, the proportion of intermittent power sources such as wind power and photovoltaics increases. Energy storage power stations have become a core support for grid peak and frequency regulation, as well as peak shaving and valley filling. Lithium secondary batteries (also known as lithium-ion batteries) are considered ideal for energy storage power stations due to their high energy density, rapid response, and flexible deployment. However, conventional lithium secondary batteries suffer from rapid discharge capacity decay at high rates, limiting their application. A battery's rate performance refers to its ability to discharge in a short period of time. The rate of insertion and extraction of the negative electrode material and the number of lithium ions it can carry are factors that affect the battery's rate performance. Currently, most battery negative electrode materials use graphite or graphitized carbon materials, but these materials have limited rate performance. Batteries are prone to capacity loss and reduced cycle life at high-rate discharge, limiting their application in the energy storage field. Therefore, research on new negative electrode materials is key to improving battery rate performance.

[0003] In addition, traditional lithium secondary battery systems also have shortcomings in high and low temperature cycle performance, and it is difficult to meet the comprehensive performance requirements of electronic equipment such as all-weather, high power, and long life put forward by new power systems.

[0004] Therefore, developing a new type of lithium secondary battery with a wide temperature range and high rate is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] The present invention provides a wide temperature range, high voltage, high rate lithium secondary battery, which has excellent high and low temperature cycle performance and high rate discharge performance.

[0006] The present invention also provides an application of the wide-temperature-range, high-voltage, high-rate lithium secondary battery in electronic devices. Research by the inventors has shown that the wide-temperature-range, high-voltage, high-rate lithium secondary battery has excellent high- and low-temperature cycling performance and high-rate discharge performance, and therefore can be applied to electronic devices.

[0007] The present invention provides a lithium secondary battery with wide temperature range, high voltage and high rate, wherein the lithium secondary battery comprises a negative electrode sheet;

[0008] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector; the negative electrode active layer includes a negative electrode active material, a conductive agent, a thickener and a binder;

[0009] The conductive agent is a manganese selenide / acidified carbon nanotube composite material made from raw materials including acidified carbon nanotubes and manganese selenide.

[0010] The wide temperature range, high voltage, and high rate lithium secondary battery described above is obtained by a preparation method comprising the following steps:

[0011] The carbon nanotubes are added to concentrated nitric acid and stirred, then washed with deionized water until the pH is neutral, and dried to obtain acidified carbon nanotubes;

[0012] mixing the acidified carbon nanotubes and manganese selenide and then subjecting them to ball milling to obtain a primary composite material;

[0013] Under the protection of an argon atmosphere, the primary composite material is subjected to laser irradiation treatment using a femtosecond laser to obtain the manganese selenide / oxidized carbon nanotube composite material.

[0014] In the wide temperature range, high voltage, and high rate lithium secondary battery as described above, in the primary composite material, the mass ratio of the acidified carbon nanotubes to the manganese selenide is 1:(0.4-0.6).

[0015] For the wide temperature range, high voltage, and high rate lithium secondary battery as described above, the laser irradiation treatment has a power of 200-250 mW and a time of 20-35 seconds.

[0016] For the lithium secondary battery with wide temperature range, high voltage and high rate as described above, the rotation speed during the ball milling process is 300-500 r / min and the time is 10-20 min.

[0017] For the wide temperature range, high voltage, and high rate lithium secondary battery as described above, the stirring treatment time is 8-10 hours.

[0018] The wide temperature range, high voltage, and high rate lithium secondary battery as described above further comprises:

[0019] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector; the positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder; the conductive agent comprises at least one of conductive carbon black, acetylene black, graphene, Ketjen black, and carbon fiber;

[0020] An electrolyte comprising an organic solvent, a lithium salt and an additive; the organic solvent comprises ethyl methanesulfonate, methyl propionate and ethyl trifluoroacetate; the lithium salt comprises lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; and the additive comprises triethanolamine borate, dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and ethoxy(pentafluoro)cyclotriphosphazene.

[0021] The wide temperature range, high voltage, and high rate lithium secondary battery as described above, wherein the electrolyte is obtained by a preparation method comprising the following steps:

[0022] Under an argon atmosphere with a water content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethyl methanesulfonate, methyl propionate, and ethyl trifluoroacetate are uniformly mixed in a volume ratio of (3-5):(3-5):2 to obtain a mixed organic solvent;

[0023] adding lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate to the mixed organic solvent and mixing and stirring uniformly to obtain an initial electrolyte;

[0024] 0.3-0.5 wt % of triethanolamine borate, 0.4-0.6 wt % of dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and 0.2-0.3 wt % of ethoxy(pentafluoro)cyclotriphosphazene are added to the initial electrolyte, and the mixture is stirred and mixed uniformly to prepare the electrolyte.

[0025] In the wide temperature range, high voltage, and high rate lithium secondary battery described above, in the initial electrolyte, the concentration of lithium hexafluorophosphate is 1.0-1.5 mol / L, the concentration of lithium bis(fluorosulfonyl)imide is 0.3-0.5 mol / L, and the concentration of lithium difluorooxalatoborate is 0.05-0.1 mol / L.

[0026] The present invention also provides an electronic device comprising the wide temperature range, high voltage, and high rate lithium secondary battery.

[0027] The beneficial effects of the present invention are:

[0028] 1) The conductive agent used in the present invention is a manganese selenide / acidified carbon nanotube composite material. The carbon nanotubes are first acidified to enhance their binding force with the manganese selenide. The acidified carbon nanotubes and manganese selenide are then mixed and ball-milled to uniformly disperse the two and achieve physical bonding (relying on van der Waals forces). After laser irradiation, the acidified carbon nanotubes and manganese selenide form a coating link to obtain a manganese selenide / acidified carbon nanotube composite material. By forming a coating link between the acidified carbon nanotubes and manganese selenide, the degree of carbon nanotube agglomeration is reduced, the conductivity of the electrode material is enhanced, thereby improving the high-rate discharge performance of the lithium secondary battery and extending the battery life.

[0029] 2) The electrolyte uses low-viscosity solvents and high-concentration lithium salts to increase ionic conductivity and reduce polarization effects; three organic solvents, ethyl methanesulfonate, methyl propionate, and ethyl trifluoroacetate, are combined in a specific proportion and compounded with lithium salts and additives to make the electrolyte compatible with high voltage and a wide temperature range, thereby improving the high and low temperature cycle performance of lithium secondary batteries. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0031] Unless otherwise specified, the raw materials used in the following examples can be obtained from commercial sources; the processes used, unless otherwise specified, are conventional processes in the art.

[0032] The present invention provides a lithium secondary battery with wide temperature range, high voltage and high rate, wherein the lithium secondary battery comprises a negative electrode sheet;

[0033] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector; the negative electrode active layer includes a negative electrode active material, a conductive agent, a thickener and a binder;

[0034] The conductive agent is a manganese selenide / acidified carbon nanotube composite material made from raw materials including acidified carbon nanotubes and manganese selenide.

[0035] It can be understood that the negative electrode active layer can be located on one surface of the negative electrode current collector to form a negative electrode, or the negative electrode active layer can be located on both surfaces of the negative electrode current collector to form a negative electrode.

[0036] The negative electrode active layer of the present invention includes a conductive agent, which is a manganese selenide / acidified carbon nanotube composite material made from raw materials including acidified carbon nanotubes and manganese selenide. By forming a coating link between the acidified carbon nanotubes and the manganese selenide, the degree of agglomeration of the carbon nanotubes is reduced, the conductivity of the electrode material is enhanced, thereby improving the high-rate discharge performance and high and low-temperature cycle performance of the lithium secondary battery and extending the battery life.

[0037] The negative electrode current collector may be a conventional negative electrode current collector in the art, for example, one or more of copper foil, nickel foam, and copper foam.

[0038] The above-mentioned negative electrode active materials, thickeners and binders can all be conventional types in the field. For example, the negative electrode active material can be selected from one or more of artificial graphite, natural graphite, silicon carbon, soft carbon, and hard carbon; the thickener can be selected from one or more of carboxymethyl cellulose, hydroxymethyl cellulose, and sodium carboxymethyl cellulose; the binder can be selected from one or more of styrene-butadiene latex, polyvinyl chloride, polyvinyl pyrrole, carboxylated polyvinyl chloride, polymer alkoxide containing ethylene oxide, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, and polyvinylidene fluoride.

[0039] Furthermore, the manganese selenide / oxidized carbon nanotube composite material is obtained by a preparation method comprising the following steps:

[0040] The carbon nanotubes are added to concentrated nitric acid and stirred, then washed with deionized water until the pH is neutral, and dried to obtain acidified carbon nanotubes;

[0041] The acidified carbon nanotubes and manganese selenide are mixed and ball-milled to obtain a primary composite material;

[0042] Under the protection of argon atmosphere, the primary composite material is subjected to laser irradiation treatment by using a femtosecond laser to obtain a manganese selenide / oxidized carbon nanotube composite material.

[0043] The present invention first acidifies carbon nanotubes to enhance their bonding with other materials (manganese selenide), then mixes the acidified carbon nanotubes and manganese selenide and performs ball milling treatment to uniformly disperse the two materials and achieve physical bonding. After laser irradiation treatment, a manganese selenide / acidified carbon nanotube composite material is obtained. By forming a coating link between the acidified carbon nanotubes and the manganese selenide, the degree of agglomeration of the carbon nanotubes is reduced, the conductivity of the electrode material is enhanced, and the high-rate discharge performance and high-low temperature cycle performance of the lithium secondary battery are improved, thereby extending its service life.

[0044] The carbon nanotubes mentioned above can be conventional types in the art, and single-walled carbon nanotubes are preferred.

[0045] In one embodiment, the mass ratio of the acidified carbon nanotubes to the manganese selenide in the primary composite material is 1:(0.4-0.6). For example, the mass ratio of the acidified carbon nanotubes to the manganese selenide in the primary composite material can be 1:0.4, 1:0.5, or 1:0.6.

[0046] In a specific embodiment, in the above laser irradiation treatment, the power is 200-250 mW and the time is 20-35 seconds.

[0047] Specifically, during the laser irradiation treatment, the power may be any one of 200 mW, 210 mW, 220 mW, 230 mW, 240 mW, and 250 mW, or a range consisting of any two of them;

[0048] The time can be any one of 20 seconds, 25 seconds, 30 seconds, 35 seconds, or a range consisting of any two of them.

[0049] When the power and time of the laser irradiation treatment are within the above ranges, sufficient coating links can be generated between the acidified carbon nanotubes and the manganese selenide.

[0050] In a specific embodiment, in the ball milling treatment, the ball milling speed is 300-500 r / min, and the ball milling time is 10-20 min.

[0051] Specifically, during the ball milling process, the rotation speed may be any one of 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, or a range consisting of any two thereof;

[0052] The time can be any one of 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, or a range consisting of any two of them.

[0053] When the rotation speed and time of the ball milling treatment are within the above ranges, the acidified carbon nanotubes and the manganese selenide can be evenly dispersed, achieving more complete physical combination.

[0054] The present invention does not particularly limit the specific time of the above-mentioned stirring treatment. In a specific embodiment, the stirring treatment time is 8-10 hours. For example, the stirring treatment time can be any one of 8 hours, 9 hours, and 10 hours, or a range consisting of any two of them.

[0055] In a specific embodiment, the lithium secondary battery further includes:

[0056] A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector; the positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder; the conductive agent comprises at least one of conductive carbon black, acetylene black, graphene, Ketjen black, and carbon fiber;

[0057] An electrolyte comprising an organic solvent, a lithium salt and an additive; the organic solvent comprises ethyl methanesulfonate, methyl propionate and ethyl trifluoroacetate; the lithium salt comprises lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; and the additive comprises triethanolamine borate, dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and ethoxy(pentafluoro)cyclotriphosphazene.

[0058] In the embodiment of the present invention, the positive electrode current collector may be a conventional positive electrode current collector in the art, for example, one or more of aluminum foil and nickel foil.

[0059] The above-mentioned positive electrode active materials and binders can use conventional types in the field. For example, the positive electrode active material can be selected from one or more of lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide; the binder can be selected from one or more of polyvinylidene fluoride and polytetrafluoroethylene.

[0060] In a specific embodiment, the electrolyte is obtained by a preparation method comprising the following steps:

[0061] Under an argon atmosphere with a water content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethyl methanesulfonate, methyl propionate, and ethyl trifluoroacetate are uniformly mixed in a volume ratio of (3-5):(3-5):2 to obtain a mixed organic solvent;

[0062] adding lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate into a mixed organic solvent and mixing and stirring uniformly to obtain an initial electrolyte;

[0063] 0.3-0.5 wt % of triethanolamine borate, 0.4-0.6 wt % of dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and 0.2-0.3 wt % of ethoxy(pentafluoro)cyclotriphosphazene are added to the initial electrolyte, and the mixture is stirred and mixed uniformly to prepare an electrolyte.

[0064] In a specific embodiment, in the above-mentioned initial electrolyte, the concentration of lithium hexafluorophosphate is 1.0-1.5 mol / L, for example, the concentration of lithium hexafluorophosphate is 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L; the concentration of lithium bis(fluorosulfonyl)imide is 0.3-0.5 mol / L, for example, the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L, 0.4 mol / L or 0.5 mol / L; the concentration of lithium difluorooxalatoborate is 0.05-0.1 mol / L, for example, the concentration of lithium difluorooxalatoborate is 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, etc.

[0065] When the concentrations of lithium hexafluorophosphate, lithium bisfluorosulfonyl imide, and lithium difluorooxalatoborate in the initial electrolyte are within the above ranges, lithium hexafluorophosphate, lithium bisfluorosulfonyl imide, and lithium difluorooxalatoborate can fully exert a synergistic effect, thereby preparing the above electrolyte.

[0066] The present invention also provides an electronic device comprising the wide-temperature-range, high-voltage, high-rate lithium secondary battery. Research by the inventors has shown that the wide-temperature-range, high-voltage, high-rate lithium secondary battery exhibits excellent high- and low-temperature cycling performance and high-rate discharge performance, and therefore can be used in electronic devices.

[0067] The present invention is further described below through specific examples.

[0068] Example 1

[0069] This embodiment provides a lithium secondary battery with a wide temperature range, high voltage, and high rate, and a lithium secondary battery prepared by a method comprising the following steps:

[0070] 1. Preparation of negative electrode sheet

[0071] (1) Preparation of conductive agent:

[0072] The conductive agent is a manganese selenide / oxidized carbon nanotube composite material;

[0073] The preparation method of the manganese selenide / oxidized carbon nanotube composite material comprises:

[0074] Acidification with concentrated nitric acid: The single-walled carbon nanotubes were added to concentrated nitric acid and stirred for 10 hours. After cooling to room temperature, the mixture was filtered and then slowly poured into deionized water for washing. The mixture was repeatedly washed with deionized water until the pH was neutral. The acidified carbon nanotubes were obtained after drying.

[0075] The acidified carbon nanotubes and manganese selenide powder were mixed in a mass ratio of 1:0.5, and then ball milled in a ball mill at a speed of 400 r / min for 15 minutes to obtain a primary composite material;

[0076] Under the protection of an argon atmosphere, the primary composite material was irradiated with a femtosecond laser having a power of 220 mW for 30 seconds to obtain a manganese selenide / oxidized carbon nanotube composite material.

[0077] (2) Preparation of negative electrode sheet:

[0078] Artificial graphite, manganese selenide / oxidized carbon nanotube composite material, sodium carboxymethyl cellulose (CMC) and styrene-butadiene latex (SBR) were added to deionized water in a mass ratio of 95:2:1.5:1.5, and the negative electrode slurry was obtained after stirring and dispersion; the negative electrode slurry was coated on the surface of the copper foil current collector and dried, and then rolled and baked to obtain the negative electrode sheet.

[0079] 2. Preparation of positive electrode sheet

[0080] Lithium iron phosphate, acetylene black and polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone (NMP) in a mass ratio of 94:3:3, and the positive electrode slurry is obtained after stirring and dispersion; the positive electrode slurry is coated on the surface of the aluminum foil current collector and then dried, and the positive electrode sheet is obtained after rolling and baking.

[0081] 3. Prepare electrolyte

[0082] In a glove box filled with argon (H2O content <0.1ppm, O2 content <0.1ppm), ethyl methanesulfonate, methyl propionate, and ethyl trifluoroacetate were mixed in a volume ratio of 3:5:2 to obtain a mixed organic solvent;

[0083] Adding lithium salt to the mixed organic solvent and mixing and stirring uniformly to make the concentration of lithium hexafluorophosphate 1.2 mol / L, the concentration of lithium bis(fluorosulfonyl)imide 0.3 mol / L, and the concentration of lithium difluorooxalatoborate 0.05 mol / L, stirring and mixing uniformly to obtain an initial electrolyte;

[0084] 0.3 wt % of triethanolamine borate, 0.5 wt % of dimethoxy(methyl)(3,3,3-trifluoropropyl)silane, and 0.2 wt % of ethoxy(pentafluoro)cyclotriphosphazene were added to the initial electrolyte, and the mixture was stirred and mixed to obtain an electrolyte.

[0085] 4. Preparation of lithium secondary batteries

[0086] The negative electrode sheet, the positive electrode sheet and the polyethylene separator are assembled into a button-type battery in a certain manner, and the electrolyte is injected and packaged to obtain a lithium secondary battery.

[0087] Example 2

[0088] The difference between this embodiment and embodiment 1 is that the acidified carbon nanotubes and the manganese selenide powder are mixed in a mass ratio of 1:0.4, and the ball milling treatment is carried out in a ball mill at a speed of 300 r / min for 10 minutes, and the primary composite material is laser irradiated for 35 seconds using a femtosecond laser with a power of 200 mW. The rest is the same as in embodiment 1.

[0089] Example 3

[0090] The difference between this embodiment and embodiment 1 is that the acidified carbon nanotubes and the manganese selenide powder are mixed in a mass ratio of 1:0.6, and the ball milling treatment is carried out in a ball mill at a speed of 500 r / min for 10 minutes, and the primary composite material is laser irradiated for 20 seconds using a femtosecond laser with a power of 250 mW. The rest is the same as in embodiment 1.

[0091] Comparative Example 1

[0092] The difference between this comparative example and Example 1 is that the single-walled carbon nanotubes are not subjected to concentrated nitric acid acidification, ball milling, or laser irradiation. The single-walled carbon nanotubes and manganese selenide powder are directly mixed and stirred at a mass ratio of 1:0.5 for 15 minutes to obtain a mixture that serves as the conductive agent. The rest is the same as in Example 1.

[0093] Comparative Example 2

[0094] The difference between this comparative example and Example 1 is that a femtosecond laser with a power of 500 mW is used to perform laser irradiation treatment on the primary composite material for 30 seconds. The rest is the same as Example 1.

[0095] Comparative Example 3

[0096] The difference between this comparative example and Example 1 is that a femtosecond laser with a power of 220 mW is used to perform laser irradiation treatment on the primary composite material for 10 seconds. The rest is the same as Example 1.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 1 is that a commercially available conventional electrolyte is used as the electrolyte, and the rest is the same as Example 1.

[0099] Verification test

[0100] The lithium secondary batteries prepared in the above embodiments and comparative examples were tested respectively: fully charged with a constant current and constant voltage of 1C, left for 2 hours, and the capacity retention rate under different discharge rates was tested at different temperatures (room temperature (25°C), low temperature (-40°C), and high temperature (60°C) in the voltage test range of 2.75V-4.8V. The test results are shown in Table 1.

[0101] Table 1 Test results

[0102]

[0103]

[0104] As can be seen from Table 1, the lithium secondary battery prepared using the manganese selenide / oxidized carbon nanotube composite material provided by the embodiment of the present invention has excellent high and low temperature cycle performance and high rate discharge performance. At the same time, the battery has a low capacity retention rate loss after cyclic high rate discharge. Since the composite nanomaterial is not modified in the comparative example 1 group, the carbon nanotubes and manganese selenide can only play a role in a dispersed form, and the overall performance is not as good as that of the embodiment 1 group. The comparative example 2 group uses a femtosecond laser with a power of 500mW to irradiate the primary composite material for 30 seconds. The inventors have found through multiple experiments that when the power is higher than 250mW and the treatment time is greater than 25s, the already formed encapsulating links will be destroyed, forming agglomerates that are difficult to separate, resulting in a significant reduction in its performance. The comparative example 3 group uses a femtosecond laser with a power of 220mW to irradiate the primary composite material for 10 seconds. Due to insufficient treatment time, only a small amount of encapsulating links are formed, and its performance is poor. In comparative example 4, the electrolyte was replaced with a conventional electrolyte. The electrolyte used in the present invention is a carrier that enables the battery as a whole to adapt to high and low temperatures, so it has a greater impact on the high and low temperature performance of the battery.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium secondary battery with a wide temperature range, high voltage and high rate, characterized in that: The lithium secondary battery includes a negative electrode sheet; The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer provided on at least one surface of the negative electrode current collector; the negative electrode active layer includes a negative electrode active material, a conductive agent, a thickener and a binder; The conductive agent is a manganese selenide / acidified carbon nanotube composite material made from raw materials including acidified carbon nanotubes and manganese selenide.

2. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 1, characterized in that: The manganese selenide / oxidized carbon nanotube composite material is obtained by a preparation method comprising the following steps: The carbon nanotubes are added to concentrated nitric acid and stirred, then washed with deionized water until the pH is neutral, and dried to obtain acidified carbon nanotubes; mixing the acidified carbon nanotubes and manganese selenide and then subjecting them to ball milling to obtain a primary composite material; Under the protection of an argon atmosphere, the primary composite material is subjected to laser irradiation treatment using a femtosecond laser to obtain the manganese selenide / oxidized carbon nanotube composite material.

3. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 2, characterized in that: In the primary composite material, the mass ratio of the acidified carbon nanotubes to the manganese selenide is 1:(0.4-0.6).

4. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 2, characterized in that: During the laser irradiation treatment, the power is 200-250 mW and the time is 20-35 seconds.

5. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 2, characterized in that: During the ball milling process, the rotation speed is 300-500 r / min and the time is 10-20 min.

6. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 2, characterized in that: The stirring time is 8-10 hours.

7. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 2, characterized in that: The lithium secondary battery further comprises: A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active layer disposed on at least one surface of the positive electrode current collector; the positive electrode active layer comprises a positive electrode active material, a conductive agent, and a binder; the conductive agent comprises at least one of conductive carbon black, acetylene black, graphene, Ketjen black, and carbon fiber; An electrolyte comprising an organic solvent, a lithium salt and an additive; the organic solvent comprises ethyl methanesulfonate, methyl propionate and ethyl trifluoroacetate; the lithium salt comprises lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate; and the additive comprises triethanolamine borate, dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and ethoxy(pentafluoro)cyclotriphosphazene.

8. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 7, characterized in that: The electrolyte is obtained by a preparation method comprising the following steps: Under an argon atmosphere with a water content of less than 0.1 ppm and an oxygen content of less than 0.1 ppm, ethyl methanesulfonate, methyl propionate, and ethyl trifluoroacetate are uniformly mixed in a volume ratio of (3-5):(3-5):2 to obtain a mixed organic solvent; adding lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide and lithium difluorooxalatoborate into the mixed organic solvent and mixing and stirring uniformly to obtain an initial electrolyte; 0.3-0.5 wt % of triethanolamine borate, 0.4-0.6 wt % of dimethoxy(methyl)(3,3,3-trifluoropropyl)silane and 0.2-0.3 wt % of ethoxy(pentafluoro)cyclotriphosphazene are added to the initial electrolyte, and the mixture is stirred and mixed uniformly to prepare the electrolyte.

9. The wide temperature range, high voltage, high rate lithium secondary battery according to claim 8, characterized in that: In the initial electrolyte, the concentration of lithium hexafluorophosphate is 1.0-1.5 mol / L, the concentration of lithium bis(fluorosulfonyl)imide is 0.3-0.5 mol / L, and the concentration of lithium difluorooxalatoborate is 0.05-0.1 mol / L.

10. Use of the wide temperature range, high voltage, high rate lithium secondary battery according to any one of claims 1 to 9 in electronic equipment.

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