A lithium titanate battery

Abstract

The application discloses a lithium titanate battery and relates to the technical field of batteries.The battery comprises a positive electrode, a negative electrode, an electrolyte and a diaphragm, wherein the electrolyte is added with an adduct synthesized from dimethyl fumarate and benzidine in a specific molar ratio as a viscosity regulator, which effectively reduces the viscosity growth trend of the electrolyte at low temperature and improves the migration rate of lithium ions.The electrolyte further comprises lithium salt, organic solvent and auxiliary additives, which are beneficial to optimizing the low-temperature performance and cycle stability of the battery.The positive electrode active material is one or more of lithium iron phosphate, lithium manganate, lithium cobaltate or nickel-manganese-cobalt ternary material, and the negative electrode active material is lithium titanate, which is further combined with additives such as lithium nitrate and fluoroethylene carbonate, so that the capacity retention rate and charge-discharge efficiency of the battery at an extreme low temperature environment of-40 DEG C are significantly improved.The lithium titanate battery provided by the application has excellent low-temperature adaptability, safety and long cycle life, and is suitable for high-cold-area power batteries and energy storage system applications.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a lithium titanate battery. Background Technology

[0002] Lithium titanate batteries, as a novel type of lithium-ion battery, exhibit excellent cycle stability and safety performance due to the stable "zero-strain" structure of lithium titanate as their negative electrode material, resulting in minimal volume change during charging and discharging. They are widely used in power batteries and energy storage systems. However, with the diversification of application environments, especially in extreme cold conditions such as -40°C, the performance of lithium titanate batteries still faces many challenges.

[0003] As the medium for lithium ion migration between the positive and negative electrodes, the performance of the electrolyte directly affects the battery's rate capability, cycle life, and low-temperature adaptability. In existing technologies, electrolytes are generally composed of organic carbonate solvents combined with lithium salts. However, these electrolytes exhibit a significant increase in viscosity and may even solidify at low temperatures. The electrolyte viscosity increases exponentially with decreasing temperature, leading to a significant decrease in the lithium-ion diffusion rate. This, in turn, causes defects such as increased internal resistance, severe capacity decay, and reduced power output, severely limiting the practical application of lithium titanate batteries in low-temperature environments. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium titanate battery that effectively reduces the viscosity increase trend of the electrolyte at low temperatures and improves the migration rate of lithium ions.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A lithium titanate battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The electrolyte is made from a viscosity modifier, a lithium salt, auxiliary additives, and an organic solvent. The viscosity modifier is an adduct of dimethyl fumarate and benzidine.

[0007] Preferably, the molar ratio of dimethyl fumarate to benzidine is (1-1.2):1.

[0008] Preferably, the viscosity modifier accounts for 0.5-3% of the total mass of the electrolyte.

[0009] Preferably, the organic solvent includes methyl ethyl carbonate, ethyl propionate, and propylene carbonate, and the organic solvent accounts for 70-90% of the total mass of the electrolyte.

[0010] Preferably, the mass ratio of methyl ethyl carbonate, ethyl propionate, and propylene carbonate is (20-60):(5-40):(10-30).

[0011] Preferably, the positive electrode includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector, wherein the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, or nickel-manganese-cobalt ternary materials.

[0012] Preferably, the negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, wherein the negative electrode active material is lithium titanate.

[0013] Preferably, the lithium salt is one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, or lithium difluorooxalateborate, and the mass of the lithium salt accounts for 10-20% of the total mass of the electrolyte.

[0014] Preferably, the mass of the auxiliary additive accounts for 0.1-2.0% of the total mass of the electrolyte.

[0015] Preferably, the electrolyte also includes lithium nitrate as a raw material, wherein the mass of lithium nitrate accounts for 0.1-0.5% of the total mass of the electrolyte.

[0016] The beneficial effects of this invention are:

[0017] 1. The electrolyte in the lithium titanate battery provided by this invention, by introducing an adduct of dimethyl fumarate and benzidine as a viscosity modifier, effectively improves the fluidity and ion transport performance of the electrolyte at low temperatures. This adduct forms a dynamic hydrogen bond network with the oxygen atoms of the carbonate solvent through amino groups in the electrolyte, effectively suppressing the tendency of solvent molecules to oriented and crystallize due to reduced thermal motion at low temperatures. This significantly reduces the viscosity increase of the electrolyte at low temperatures, thereby improving the lithium-ion migration rate of the lithium titanate battery at low temperatures.

[0018] 2. Fluorinated ethylene carbonate (FEC) and lithium nitrate synergistically optimize electrode interface stability in the electrolyte. FEC effectively suppresses electrolyte side reactions and lithium dendrite growth at low temperatures by optimizing the electrolyte surface film; lithium nitrate, on the other hand, enhances the mechanical strength and ion transport capacity of the film by participating in the composition regulation of the electrode surface film. Together, they significantly reduce interfacial impedance at low temperatures, improve the reversible insertion / extraction efficiency of lithium ions on the negative electrode surface, thereby improving the low-temperature cycle stability and safety of the battery. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0020] Example 1

[0021] A lithium titanate battery includes a positive electrode, a negative electrode, an electrolyte, and a separator.

[0022] The raw materials of the electrolyte and their mass percentages are shown in Table 1 below.

[0023] Table 1

[0024]

[0025] The molar ratio of dimethyl fumarate to benzidine is 1:1.

[0026] The specific steps for the addition of dimethyl fumarate and benzidine are as follows: Under nitrogen protection, dimethyl fumarate and benzidine in a molar ratio of 1:1 are added to an ethanol solvent (the amount of solvent is 5 times the total mass of the reactants), and a small amount of piperidine (the amount of piperidine is 0.5% of the total mass of the reactants) is added as a catalyst. The mixture is refluxed at 70°C for 5 hours. After the reaction is completed, the mixture is cooled to room temperature, the solvent is removed by vacuum distillation, and cold water (the volume of cold water is 2 times the volume of the reaction system) is added to precipitate a solid product. The product is filtered and washed three times with water, and then vacuum dried (drying temperature 60°C, drying time 12 hours) to obtain the adduct of dimethyl fumarate and benzidine.

[0027] The specific steps for preparing the electrolyte are as follows: Weigh out methyl ethyl carbonate, ethyl propionate, and propylene carbonate according to the specified ratio, and mix them evenly at 25°C and a stirring speed of 300 r / min; then add lithium hexafluorophosphate according to the specified ratio, and dissolve it completely at 30°C and a stirring speed of 400 r / min; next, add viscosity modifier, fluoroethylene carbonate, and lithium nitrate, and continue stirring at 35°C and a stirring speed of 500 r / min until completely dissolved and mixed evenly; finally, filter the solution using a 0.22 μm filter membrane and store it in a dry environment for later use.

[0028] The positive electrode includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector. The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, or nickel-manganese-cobalt ternary materials. Specifically, in this embodiment, the positive electrode active material is lithium cobalt oxide, and the positive electrode current collector is aluminum foil.

[0029] The specific steps for preparing the positive electrode are as follows: Lithium cobalt oxide, conductive agent SuperP, and binder PVDF are mixed in a mass ratio of 95:2.5:2.5. N-methylpyrrolidone (the amount of N-methylpyrrolidone is 0.5 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 40℃ and a stirring speed of 500-2800r / min to form a slurry. The slurry is coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. Then, it is cold-pressed under a pressure of 10MPa to obtain the positive electrode sheet, which is then cut into sheets with a size of 5cm×5cm.

[0030] The negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. The negative electrode active material is lithium titanate.

[0031] The specific steps for preparing the negative electrode are as follows: Lithium titanate, conductive agent SuperP and binder PVDF are mixed in a mass ratio of 93:2:5. N-methylpyrrolidone (the amount of N-methylpyrrolidone is 1.4 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 35℃ and a stirring speed of 800-2500r / min to form a slurry. The slurry is then coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. After cold pressing at a pressure of 8MPa, the negative electrode sheet is obtained and cut into sheets with a size of 5cm×5cm.

[0032] Lithium titanate battery assembly: In an argon-filled glove box (moisture content <10ppm, oxygen content <10ppm), the positive electrode, separator, and negative electrode are stacked sequentially to form the cell structure. The cell is then installed into an aluminum-plastic film battery casing, and the prepared electrolyte is injected (the electrolyte injection volume is 1.2 times the cell volume). After sealing and standing for 24 hours, formation and aging treatment are performed at 25℃ and constant current / constant voltage charging mode (0.1C constant current charging to 2.8V, then constant voltage charging until the current drops to 0.02C) (aging time 72 hours, aging temperature 40℃).

[0033] Example 2

[0034] A lithium titanate battery includes a positive electrode, a negative electrode, an electrolyte, and a separator.

[0035] The raw materials of the electrolyte and their mass percentages are shown in Table 2 below.

[0036] Table 2

[0037]

[0038] The molar ratio of dimethyl fumarate to benzidine is 1.1:1.

[0039] The specific steps for the addition of dimethyl fumarate and benzidine are as follows: Under nitrogen protection, dimethyl fumarate and benzidine in a molar ratio of 1.1:1 are added to an ethanol solvent (the amount of solvent is 5 times the total mass of the reactants), and a small amount of piperidine (the amount of piperidine is 0.5% of the total mass of the reactants) is added as a catalyst. The mixture is refluxed at 70°C for 5 hours. After the reaction is completed, the mixture is cooled to room temperature, the solvent is removed by vacuum distillation, cold water (the volume of cold water is 2 times the volume of the reaction system) is added to precipitate the solid product, which is then filtered and washed three times with water. After vacuum drying (drying temperature 60°C, drying time 12 hours), the adduct of dimethyl fumarate and benzidine is obtained.

[0040] The specific steps for preparing the electrolyte are as follows: Weigh out methyl ethyl carbonate, ethyl propionate, and propylene carbonate according to the specified ratio, and mix them evenly at 25°C and a stirring speed of 300 r / min; then add lithium hexafluorophosphate according to the specified ratio, and dissolve it completely at 30°C and a stirring speed of 400 r / min; next, add viscosity modifier, fluoroethylene carbonate, and lithium nitrate, and continue stirring at 35°C and a stirring speed of 500 r / min until completely dissolved and mixed evenly; finally, filter the solution using a 0.22 μm filter membrane and store it in a dry environment for later use.

[0041] The positive electrode includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector. The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese oxide, or nickel-manganese-cobalt ternary materials. Specifically, in this embodiment, the positive electrode active material is lithium iron phosphate, and the positive electrode current collector is aluminum foil.

[0042] The specific steps for preparing the positive electrode are as follows: Lithium cobalt oxide, conductive agent SuperP, and binder PVDF are mixed in a mass ratio of 95:2.5:2.5. N-methylpyrrolidone (the amount of N-methylpyrrolidone is 0.5 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 40℃ and a stirring speed of 500-2800r / min to form a slurry. The slurry is coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. Then, it is cold-pressed under a pressure of 10MPa to obtain the positive electrode sheet, which is then cut into sheets with a size of 5cm×5cm.

[0043] The negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. The negative electrode active material is lithium titanate.

[0044] The specific steps for preparing the negative electrode are as follows: Lithium titanate, conductive agent SuperP and binder PVDF are mixed in a mass ratio of 93:2:5. N-methylpyrrolidone (the amount of N-methylpyrrolidone is 1.4 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 35℃ and a stirring speed of 800-2500r / min to form a slurry. The slurry is then coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. After cold pressing at a pressure of 8MPa, the negative electrode sheet is obtained and cut into sheets with a size of 5cm×5cm.

[0045] Lithium titanate battery assembly: In an argon-filled glove box (moisture content <10ppm, oxygen content <10ppm), the positive electrode, separator, and negative electrode are stacked sequentially to form the cell structure. The cell is then installed into an aluminum-plastic film battery casing, and the prepared electrolyte is injected (the electrolyte injection volume is 1.2 times the cell volume). After sealing and standing for 24 hours, formation and aging treatment are performed at 25℃ and constant current / constant voltage charging mode (0.1C constant current charging to 2.8V, then constant voltage charging until the current drops to 0.02C) (aging time 72 hours, aging temperature 40℃).

[0046] Example 3

[0047] A lithium titanate battery includes a positive electrode, a negative electrode, an electrolyte, and a separator.

[0048] The raw materials of the electrolyte and their mass percentages are shown in Table 3 below.

[0049] Table 3

[0050]

[0051] The molar ratio of dimethyl fumarate to benzidine is 1.2:1.

[0052] The specific steps for the addition of dimethyl fumarate and benzidine are as follows: Under nitrogen protection, dimethyl fumarate and benzidine in a molar ratio of 1.2:1 are added to an ethanol solvent (the amount of solvent is 5 times the total mass of the reactants), and a small amount of piperidine (the amount of piperidine is 0.5% of the total mass of the reactants) is added as a catalyst. The mixture is refluxed at 70°C for 5 hours. After the reaction is completed, the mixture is cooled to room temperature, the solvent is removed by vacuum distillation, and cold water (the volume of cold water is 2 times the volume of the reaction system) is added to precipitate a solid product. The product is filtered and washed three times with water, and then vacuum dried (drying temperature 60°C, drying time 12 hours) to obtain the adduct of dimethyl fumarate and benzidine.

[0053] The specific steps for preparing the electrolyte are as follows: Weigh out methyl ethyl carbonate, ethyl propionate, and propylene carbonate according to the specified ratio, and mix them evenly at 25°C and a stirring speed of 300 r / min; then add lithium hexafluorophosphate according to the specified ratio, and dissolve it completely at 30°C and a stirring speed of 400 r / min; next, add viscosity modifier, fluoroethylene carbonate, and lithium nitrate, and continue stirring at 35°C and a stirring speed of 500 r / min until completely dissolved and mixed evenly; finally, filter the solution using a 0.22 μm filter membrane and store it in a dry environment for later use.

[0054] The positive electrode includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector. The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, or nickel-manganese-cobalt ternary materials. Specifically, in this embodiment, the positive electrode active material is lithium cobalt oxide, and the positive electrode current collector is aluminum foil.

[0055] The specific steps for preparing the positive electrode are as follows: Lithium cobalt oxide, conductive agent SuperP, and binder PVDF are mixed in a mass ratio of 95:2.5:2.5. N-methylpyrrolidone (0.5 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 40℃ and a stirring speed of 500-2800r / min to form a slurry. The slurry is coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. After cold pressing at a pressure of 10MPa, the positive electrode sheet is obtained and cut into sheets with a size of 5cm×5cm.

[0056] The negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector. The negative electrode active material is lithium titanate.

[0057] The specific steps for preparing the negative electrode are as follows: Lithium titanate, conductive agent SuperP and binder PVDF are mixed in a mass ratio of 93:2:5. N-methylpyrrolidone (the amount of N-methylpyrrolidone is 1.4 times the total mass of the mixture) is added as a solvent. The mixture is stirred evenly at a temperature of 35℃ and a stirring speed of 800-2500r / min to form a slurry. The slurry is then coated onto the surface of aluminum foil with a wet coating thickness of 20μm. The foil is dried at 90-110℃ for 1 hour. After cold pressing at a pressure of 8MPa, the negative electrode sheet is obtained and cut into sheets with a size of 5cm×5cm.

[0058] Lithium titanate battery assembly: In an argon-filled glove box (moisture content <10ppm, oxygen content <10ppm), the positive electrode, separator, and negative electrode are stacked sequentially to form the cell structure. The cell is then installed into an aluminum-plastic film battery casing, and the prepared electrolyte is injected (the electrolyte injection volume is 1.2 times the cell volume). After sealing and standing for 24 hours, formation and aging treatment are performed at 25℃ and constant current / constant voltage charging mode (0.1C constant current charging to 2.8V, then constant voltage charging until the current drops to 0.02C) (aging time 72 hours, aging temperature 40℃).

[0059] Comparative Example 1

[0060] The difference from Example 1 is that no dimethyl fumarate-benzidine adduct is added to the electrolyte as a viscosity modifier.

[0061] Comparative Example 2

[0062] The difference from Example 1 is that an equal amount of propylene carbonate is used in the electrolyte instead of the adduct of dimethyl fumarate and benzidine.

[0063] Comparative Example 3

[0064] The difference from Example 1 is that no fluoroethylene carbonate is added to the electrolyte.

[0065] Comparative Example 4

[0066] The difference from Example 1 is that lithium nitrate is not added to the electrolyte.

[0067] Comparative Example 5

[0068] The difference from Example 1 is that neither FEC nor lithium nitrate is added to the electrolyte.

[0069] test:

[0070] 1. Low-temperature performance test

[0071] After activating the lithium titanate batteries of Examples 1-3 and Comparative Examples 1-5 with 1-2 charge-discharge cycles at 25°C, they were placed in a test chamber set at -40°C and stabilized for at least 2 hours. Charge-discharge tests were conducted with a constant current of 0.2C and a voltage range of 1.5V-2.8V. Charging was stopped at 2.8V, then switched to a constant voltage and a current of 0.02C, and finally discharged to 1.5V. Relevant data were recorded. Capacity retention, initial efficiency, and polarization resistance were calculated to evaluate the battery's capacity decay, energy conversion efficiency, and ion transport performance at low temperatures.

[0072] The test results for low-temperature performance are shown in Table 4.

[0073] 2. Cyclic stability test

[0074] The test chamber temperature was set to -40℃ and stabilized for at least 2 hours. Batteries from Examples 1-3 and Comparative Examples 1-5 were placed inside the chamber and connected to the test system. 8000 charge-discharge cycles were performed at a constant current of 0.5C and a voltage range of 1.5V-2.8V. The batteries were charged to 2.8V, then switched to a constant voltage of 0.02C, and discharged to 1.5V. Data for each cycle was recorded. The capacity decay rate was obtained by calculating the ratio of the capacity at the 8000th discharge cycle to the capacity at the first cycle, thus evaluating the battery's capacity retention and cycle stability during long-term cycling.

[0075] The test results of the cyclic stability test are shown in Table 5.

[0076] 3. Electrolyte viscosity test

[0077] Take 50-100 mL of electrolyte samples without bubbles or impurities prepared in Examples 1-3 and Comparative Examples 1-5. Set the low-temperature constant temperature bath to -20℃ and stabilize it. Keep the sample at this temperature for 30 minutes. Immerse the viscometer rotor in the center of the sample and measure it at 60 rpm. Record the data after it has stabilized for 2 minutes.

[0078] The test results of the electrolyte viscosity test are shown in Table 6.

[0079] Table 4

[0080]

[0081] Table 5

[0082]

[0083] Table 6

[0084]

[0085] Table 4 shows that: Examples 1-3 all had a capacity retention rate exceeding 91% at -40℃, an initial efficiency exceeding 98%, and a polarization resistance below 20mΩ, indicating that the electrolytes with the addition of dimethyl fumarate and benzidine adduct, fluoroethylene carbonate (FEC), and lithium nitrate significantly improved the battery's low-temperature capacity retention, energy conversion efficiency, and ion transport performance; Comparative Examples 1 and 2 had capacity retention rates of 78.4% and 81.2%, respectively, with significantly increased polarization resistance, indicating that the adduct is a key factor in reducing electrolyte viscosity at low temperatures and improving ion migration rate; Comparative Examples 3 and 4 had capacity retention rates of 85.6% and 87.9%, respectively, with higher polarization resistance than the examples, indicating that FEC and lithium nitrate synergistically improved interfacial impedance by optimizing the electrode interface film layer; Comparative Example 5 had the worst performance, verifying the synergistic necessity of the two types of additives.

[0086] As shown in Table 5, Examples 1-3 all exhibited capacity retention rates exceeding 95% and decay rates below 4.3% after 8000 cycles, demonstrating excellent cycle stability. This was attributed to the improvement of electrolyte flowability by the adduct and the stabilizing effect of FEC / lithium nitrate on the electrode interface film. Comparative Examples 1-5, on the other hand, all showed capacity retention rates below 90% and decay rates as high as 20.2% (Comparative Example 5), indicating that the lack of adduct or additives would exacerbate interfacial side reactions and significantly reduce cycle performance.

[0087] As shown in Table 6, the electrolytes of Examples 1-3 had significantly lower viscosity at -40°C than those of Comparative Examples 1-2, directly demonstrating that the dimethyl fumarate and benzidine adduct inhibited solvent crystallization and reduced low-temperature viscosity by forming a hydrogen bond network. The viscosity of Comparative Examples 3-4 was higher than that of the Examples but lower than that of Comparative Examples 1-2, indicating that FEC and lithium nitrate had little effect on viscosity and mainly played a role in interfacial stability.

[0088] In summary, this invention significantly reduces the low-temperature viscosity of the electrolyte by introducing dimethyl fumarate and benzidine adduct into the electrolyte as a viscosity modifier, and combining it with fluoroethylene carbonate and lithium nitrate, thereby optimizing the electrode interface film structure and improving the capacity retention, cycle stability and ion transport efficiency of lithium titanate batteries at -40℃.

[0089] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A lithium titanate battery, comprising a positive electrode, a negative electrode, an electrolyte, and a separator, characterized in that: The electrolyte raw materials include viscosity modifiers, lithium salts, auxiliary additives, and organic solvents; the viscosity modifier is an adduct of dimethyl fumarate and benzidine.

2. A lithium titanate battery according to claim 1, characterized in that: The molar ratio of dimethyl fumarate to benzidine is (1-1.2):

1.

3. A lithium titanate battery according to claim 1, characterized in that: The viscosity modifier accounts for 0.5-3% of the total mass of the electrolyte.

4. A lithium titanate battery according to claim 1, characterized in that: The organic solvent includes methyl ethyl carbonate, ethyl propionate, and propylene carbonate, and the organic solvent accounts for 70-90% of the total mass of the electrolyte.

5. A lithium titanate battery according to claim 4, characterized in that: The mass ratio of methyl ethyl carbonate, ethyl propionate, and propylene carbonate is (20-60):(5-40):(10-30).

6. A lithium titanate battery according to claim 1, characterized in that: The positive electrode includes a positive electrode current collector and a positive electrode active material coated on the positive electrode current collector. The positive electrode active material includes one or more of lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, or nickel-manganese-cobalt ternary materials.

7. A lithium titanate battery according to claim 1, characterized in that: The negative electrode includes a negative electrode current collector and a negative electrode active material coated on the negative electrode current collector, wherein the negative electrode active material is lithium titanate.

8. A lithium titanate battery according to claim 1, characterized in that: The lithium salt is one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, or lithium difluorooxalateborate, and the mass of the lithium salt accounts for 10-20% of the total mass of the electrolyte.

9. A lithium titanate battery according to claim 1, characterized in that: The auxiliary additive is fluoroethylene carbonate, and the mass of the auxiliary additive accounts for 0.1-2.0% of the total mass of the electrolyte.

10. A lithium titanate battery according to claim 1, characterized in that: The electrolyte also includes lithium nitrate as a raw material, and the lithium nitrate accounts for 0.1-0.5% of the total mass of the electrolyte.

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