Low-temperature-resistant sodium-ion battery

Abstract

This application discloses a low-temperature resistant sodium-ion battery, which includes a positive electrode, a negative electrode, and an electrolyte; the positive electrode active material of the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the negative electrode active material is carbon or sodium foil; the electrolyte organic solvent is a mixture of ethers and carbonates. This low-temperature resistant sodium-ion battery can operate normally in low-temperature environments. When operating at -30°C, its capacity retention rate at 0.5C can reach more than 95.7% of that at room temperature, and even at a high rate of 3C, it can still provide a discharge specific capacity of more than 66 mA·h / g.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sodium ion batteries, and particularly relates to a low-temperature-resistant sodium ion battery. BACKGROUND

[0002] The sodium ion battery has a similar working principle as the lithium ion battery, and mainly relies on the movement of sodium ions between the positive electrode and the negative electrode to work. The abundant reserves of sodium in the earth's crust and low cost make the sodium ion battery regarded as one of the ideal substitutes for the lithium ion battery.

[0003] However, as the temperature decreases, especially in a low-temperature environment below 0 DEG C, the slow diffusion kinetics of sodium ions in the electrode and the electrolyte and the increased resistance on the solid electrolyte interface hinder the sodium ion battery, which faces problems such as capacity attenuation, deterioration of electrochemical performance, decrease of discharge voltage, charging and discharging difficulty and even stop working. The above problems of the sodium ion battery in a low-temperature environment seriously limit the energy density and service life of the sodium ion battery in a low-temperature environment, which brings great challenges to the use of the sodium ion battery in a cold climate. Although the external secondary heating method and thermal management can effectively increase the local temperature to maintain the operation of the sodium ion battery in a low-temperature environment, these methods inevitably bring additional energy consumption and higher cost. SUMMARY

[0004] The low-temperature-resistant sodium ion battery provided by the application embodiment solves the technical problem of the serious performance decrease of the sodium ion battery in a low-temperature environment in the prior art.

[0005] The low-temperature-resistant sodium ion battery provided by the application embodiment includes a positive electrode sheet, a negative electrode sheet and an electrolyte; the positive electrode active material of the positive electrode sheet is Na 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the negative electrode active material of the negative electrode sheet is carbon or sodium foil; and the organic solvent of the electrolyte is a mixed system of ethers and carbonates.

[0006] In a possible implementation manner, the ratio of the positive electrode active material, the conductive additive and the binder of the positive electrode sheet is 7-8.5:1-2:0.5-1.

[0007] In a possible implementation manner, the ratio of the positive electrode active material, the conductive additive and the binder of the positive electrode sheet is 7.5:1.5:1.

[0008] In a possible implementation manner, the coating weight of the positive electrode sheet on the positive electrode current collector is 0.9-3.5 mg / cm2 .

[0009] In a possible implementation, when the negative active material of the negative electrode tab is carbon-based, the ratio of the negative active material, the conductive additive and the binder of the negative electrode tab is 7.5-8: 1-1.5: 1.

[0010] In a possible implementation, the ratio of the negative active material, the conductive additive and the binder of the negative electrode tab is 8: 1: 1.

[0011] In a possible implementation, the coating weight of the negative electrode tab on the negative current collector is 0.4-1.6 mg / cm 2 .

[0012] In a possible implementation, the concentration of the electrolyte is 0.1-1.5 mol / L.

[0013] In a possible implementation, the organic solvent includes a solvent and an additive; the solvent includes at least one of the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether; and / or the additive includes at least one of the following: fluoroethylene carbonate, vinylene carbonate, 1,3-dioxolane.

[0014] In a possible implementation, the amount of the additive is 3-5 vol%.

[0015] The technical solutions provided in the embodiments of the present application have at least the following technical effects:

[0016] The embodiments of the present application provide a low-temperature-resistant sodium ion battery, which is Na 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07O2 material is a positive active material, carbon or sodium foil is a negative active material, and the mixed system of ethers and carbonates is an organic solvent electrolyte. On the one hand, the excellent sodium ion transmission capacity of the positive active material and the special symbiotic structure that can effectively inhibit P2-O2 phase change make the low-temperature-resistant sodium ion battery have smaller polarization and lower impedance at low temperature, thereby showing good capacity retention and excellent rate performance. On the other hand, the electrolyte of the present application can still maintain high conductivity at low temperature to ensure efficient migration of sodium ions in the electrolyte at low temperature, and the thin and inorganic-rich solid electrolyte interface film (SEI) formed by it is also conducive to the transmission of sodium ions on the interface at low temperature. Therefore, the low-temperature-resistant sodium ion battery can work normally at low temperature, and when working at -30℃, the capacity retention rate at 0.5C rate can reach more than 95.7% of the normal temperature, and even at a high rate of 3C, it can still provide a discharge specific capacity of more than 66mA·h / g. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used by the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described in the following are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0018] Fig. 1 The first two cycles of charge-discharge curves of the sodium ion battery in Example 1 of the present application at normal temperature environment 25℃;

[0019] Fig. 2 The first two cycles of charge-discharge curves of the sodium ion battery in Example 1 of the present application at low temperature environment of -30℃;

[0020] Fig. 3 The cycle performance diagram of the sodium ion battery in Example 1 of the present application at low temperature environment of -30℃ and 0.5C rate;

[0021] Fig. 4 The rate performance diagram of the sodium ion battery in Example 1 of the present application at low temperature environment of -30℃. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] In the embodiments of the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "1~13" represents that all real numbers between "1~13" have been listed herein, and "1~13" is only a shorthand notation for these numerical combinations.

[0024] The lower limit and the upper limit of the "range" disclosed in the embodiments of the present application can be one or more lower limits and one or more upper limits, respectively.

[0025] Unless otherwise specified, the professional and scientific terms used in the embodiments of the present application have the same meaning as those familiar to the skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied in the embodiments of the present application.

[0026] The present application provides a low-temperature-resistant sodium ion battery, which comprises a positive electrode sheet, a negative electrode sheet and an electrolyte. The embodiments of the present application explore the preparation method and assembly conditions of the sodium ion battery by changing the composition of the electrode sheet, the composition of the electrolyte, the concentration of the electrolyte, and further study the corresponding electrochemical performance, including the cycle stability, discharge capacity and rate performance under room temperature and low temperature environment.

[0027] The positive electrode sheet provided by the present application comprises a positive electrode active material, a conductive additive, a binder and a positive electrode current collector, wherein the positive electrode sheet can be a circular sheet with a diameter of 10 mm. The positive electrode active material is Na 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive comprises at least one of Super-P, Ketjen black and carbon black; the binder is polyvinylidene fluoride; the positive electrode current collector is aluminum foil; the ratio of the positive electrode active material, the conductive additive and the binder is 7~8.5:1~2:0.5~1; the coating weight of the positive electrode sheet on the positive electrode current collector is 0.9~3.5 mg / cm 2 .

[0028] The negative electrode sheet provided by the present application is sodium foil or carbon type. The sodium foil can be a circular sheet with a diameter of 12 mm, and the carbon type negative electrode sheet can be a circular sheet with a diameter of 10 mm.

[0029] If the negative electrode is carbon-based, it comprises a negative electrode active material, a conductive additive, a binder, and a negative electrode current collector. The negative electrode active material includes at least one of graphite, hard carbon, and carbon nanotubes; the conductive additive includes at least one of Super-P, Ketjen black, and carbon black; the binder is polyvinylidene fluoride; the negative electrode current collector is aluminum foil; the ratio of the negative electrode active material, conductive additive, and binder is 7.5–8:1–1.5:1; the coating weight of the carbon negative electrode on the negative electrode current collector is 0.4–1.6 mg / cm³. 2 .

[0030] The electrolyte provided in this application comprises a sodium salt, a solvent, and additives, with a concentration of 0.1–1.5 mol / L. The sodium salt in the electrolyte includes at least one of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, and sodium perchlorate; the solvent includes at least one of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and triethylene glycol dimethyl ether; the additives include at least one of fluoroethylene carbonate, vinylene carbonate, and 1,3-dioxolane; the amount of additives is 3–5 vol%.

[0031] The superior sodium-ion transport capability and unique symbiotic structure of the positive electrode active material provided in this application, which effectively suppresses the P2-O2 phase transition, enable this low-temperature resistant sodium-ion battery to exhibit low polarization and low impedance at low temperatures, thus demonstrating good capacity retention and excellent rate performance. Simultaneously, the electrolyte, especially the ether-based electrolyte, maintains high conductivity at low temperatures, ensuring efficient sodium ion migration within the electrolyte under these conditions. Furthermore, the thin, inorganic-rich solid electrolyte interphase (SEI) film formed further facilitates sodium ion transport at the interface at low temperatures. Therefore, the low-temperature resistant sodium-ion battery provided in this application can provide a discharge specific capacity of >90 mA·h / g when operating at a rate of 0.5C at -30°C, equivalent to 95.7% of its room-temperature capacity. After 800 cycles under the above conditions, it still provides a capacity retention rate of up to 94.2%, and even at a high rate of 3C and a low temperature of -30°C, it still exhibits a discharge specific capacity of over 66 mA·h / g, where C represents 86 mA / g. Compared with existing lithium-ion batteries and sodium-ion batteries, the low-temperature resistant sodium-ion battery provided in this application shows superior capacity retention, cycle performance, and rate discharge capability in low-temperature environments.

[0032] The materials prepared in the following examples were analyzed using X-ray diffraction (XRD). The low-temperature sodium-ion batteries in the following examples were all assembled in an argon atmosphere glove box with a moisture and oxygen content of less than 0.1 ppm, and were CR2032 coin cells. After assembly, they were left to stand for 6–12 hours and then tested on the LAND battery testing system provided by Wuhan Landian Electronics Co., Ltd., with a cutoff voltage of 2.2–4.15 V. The low-temperature sodium-ion batteries underwent constant current charge-discharge tests at 0.1 C and 0.5 C, rate performance tests at 0.1–5 C, and Gitt constant current intermittent titration tests at room temperature and -20°C and -30°C, respectively. Cyclic voltammetry (CV) tests were also performed on the low-temperature sodium-ion batteries using an electrochemical workstation.

[0033] Example 1

[0034] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0035] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0036] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0037] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0038] The above-mentioned positive electrode, negative electrode, electrolyte, and 16mm diameter Whatman glass fiber membrane separator were assembled into a CR2032 coin cell in an argon glove box, and electrochemical performance was tested. Figs. 1 to 4As shown, the assembled battery has discharge specific capacities of 97.0 and 95.5 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, and retains 93.4% of the capacity at 0.1C at 3C. When tested at a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates are 92.7 and 91.4 mA·h / g, respectively, and retain 94.2% of the capacity after 800 cycles at 0.5C, and retains 72.1% of the capacity at 0.1C at 3C.

[0039] Example 2

[0040] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0041] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Ketjen Black; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0042] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0043] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0044] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 95.1 mA·h / g at 0.1C and 0.5C rates at room temperature, with a capacity retention of 93.4% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 88.2 and 81.8 mA·h / g, respectively, with a capacity retention of 78.9% after 800 cycles at 0.5C and 69.3% at 3C compared to 0.1C.

[0045] Example 3

[0046] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0047] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is carbon black; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of the positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0048] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0049] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0050] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 86.2 and 79.3 mA·h / g at room temperature and 0.1C and 0.5C rates, respectively, with a capacity retention of 80.3% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 85.4 and 77.6 mA·h / g, respectively, with a capacity retention of 89.5% after 800 cycles at 0.5C and 70.4% at 3C compared to 0.1C.

[0051] Example 4

[0052] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0053] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 8.5:1:0.5, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0054] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0055] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0056] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 87.2 and 87.0 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 91.9% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 86.0 and 82.3 mA·h / g, respectively, with a capacity retention of 61.2% after 800 cycles at 0.5C and 70.1% at 3C compared to 0.1C.

[0057] Example 5

[0058] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0059] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7:2:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0060] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0061] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0062] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 96.8 mA·h / g at 0.1C and 0.5C rates at room temperature, and retained 92.8% of the capacity at 0.1C at 3C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 92.5 and 90.9 mA·h / g, respectively. After 800 cycles at 0.5C, the capacity retention was 92.5%, and at 3C, the capacity retention was 70.9% of the capacity at 0.1C.

[0063] Example 6

[0064] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0065] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 0.9 mg / cm³. 2 .

[0066] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0067] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0068] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 95.0 and 94.2 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 93.7% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 92.5 and 92.0 mA·h / g, respectively, with a capacity retention of 87.9% after 800 cycles at 0.5C and 76.2% at 3C compared to 0.1C.

[0069] Example 7

[0070] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0071] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 3.5 mg / cm³. 2 .

[0072] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0073] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0074] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 94.2 and 90.0 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 86.5% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 87.3 and 94.5 mA·h / g, respectively, with a capacity retention of 90.1% after 800 cycles at 0.5C and 66.9% at 3C compared to 0.1C.

[0075] Example 8

[0076] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0077] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0078] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is hard carbon. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 0.5 mg / cm³. 2 .

[0079] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0080] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 95.9 mA·h / g at 0.1C and 0.5C rates at room temperature, and retained 92.2% of the capacity at 0.1C at 3C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 90.3 and 89.6 mA·h / g, respectively, with a capacity retention of 91.2% after 800 cycles at 0.5C and 70.2% of the capacity retention at 0.1C at 3C.

[0081] Example 9

[0082] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0083] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0084] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is graphite. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 0.5mg / cm³. 2 .

[0085] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0086] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 82.3 and 76.9 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 86.5% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 74.9 and 70.1 mA·h / g, respectively, with a capacity retention of 55.7% after 800 cycles at 0.5C and 61.8% at 3C compared to 0.1C.

[0087] Example 10

[0088] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0089] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0090] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is carbon nanotubes. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 0.5 mg / cm³. 2 .

[0091] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0092] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 81.1 mA·h / g at 0.1C and 77.3 mA·h / g at room temperature, with a capacity retention of 90.1% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C were 73.2 and 69.3 mA·h / g, respectively, with a capacity retention of 71.1% after 800 cycles at 0.5C and 61.6% at 3C compared to 0.1C.

[0093] Example 11

[0094] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0095] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0096] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is carbon nanotubes. The conductive additive in the negative electrode is Ketjen Black, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 0.5 mg / cm³. 2 .

[0097] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0098] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 86.5 mA·h / g at 0.1C and 0.5C rates at room temperature, and retained 89.5% of the capacity at 0.1C at 3C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 82.1 and 75.9 mA·h / g, respectively. After 800 cycles at 0.5C, the capacity retention was 83.2%, and at 3C, the capacity retention was 60.8% of the capacity at 0.1C.

[0099] Example 12

[0100] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0101] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0102] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is carbon black. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 0.5 mg / cm³. 2 .

[0103] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0104] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 81.9 and 77.3 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 86.0% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 73.9 and 67.1 mA·h / g, respectively, with a capacity retention of 48.2% after 800 cycles at 0.5C and 44.9% at 3C compared to 0.1C.

[0105] Example 13

[0106] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0107] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0108] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is hard carbon. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 7.5:1.5:1, and the coating weight on the negative current collector is 0.4 mg / cm³. 2 .

[0109] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0110] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 91.1 mA·h / g at 0.1C and 0.5C rates at room temperature, with a capacity retention of 93.0% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 87.3 and 83.9 mA·h / g, respectively, with a capacity retention of 88.3% after 800 cycles at 0.5C and 72.2% at 3C compared to 0.1C.

[0111] Example 14

[0112] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0113] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0114] In this embodiment, the negative electrode is a 10mm diameter disc, and the active material used is hard carbon. The conductive additive in the negative electrode is Super-P, the binder is polyvinylidene fluoride, and the negative current collector is aluminum foil. The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode is 8:1:1, and the coating weight on the negative current collector is 1.6 mg / cm³. 2 .

[0115] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0116] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 88.8 and 80.3 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 81.2% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 80.7 and 76.6 mA·h / g, respectively, with a capacity retention of 91.1% after 800 cycles at 0.5C and 61.2% at 3C compared to 0.1C.

[0117] Example 15

[0118] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0119] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0120] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0121] In this embodiment, the sodium salt of the electrolyte is sodium trifluoromethanesulfonate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0122] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 85.2 and 66.3 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 59.9% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 72.7 and 62.4 mA·h / g, respectively, with a capacity retention of 77.0% after 800 cycles at 0.5C and 32.8% at 3C compared to 0.1C.

[0123] Example 16

[0124] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0125] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0126] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0127] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0128] In this embodiment, the sodium salt of the electrolyte is sodium perchlorate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0129] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 46.2 and 35.7 mA·h / g at room temperature and 0.1C and 0.5C rates, respectively, with a capacity retention of 60.4% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 31.5 and 21.4 mA·h / g, respectively, with a capacity retention of 33.4% after 800 cycles at 0.5C and 52.1% at 3C compared to 0.1C.

[0130] Example 17

[0131] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0132] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0133] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0134] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is ethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0135] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. At room temperature, the discharge specific capacities at 0.1C and 0.5C rates were 92.3 and 88.5 mA·h / g, respectively, with a capacity retention of 89.9% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 88.7 and 85.3 mA·h / g, respectively, with a capacity retention of 79.9% after 800 cycles at 0.5C and 61.2% at 3C compared to 0.1C.

[0136] Example 18

[0137] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0138] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0139] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0140] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is triethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0141] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. At room temperature, the discharge specific capacities at 0.1C and 0.5C rates were 92.1 and 85.5 mA·h / g, respectively, with a capacity retention of 85.4% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 84.7 and 80.3 mA·h / g, respectively, with a capacity retention of 82.2% after 800 cycles at 0.5C and 65.1% at 3C compared to 0.1C.

[0142] Example 19

[0143] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0144] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0145] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0146] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is fluoroethylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0147] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 27.0 and 15.5 mA·h / g at room temperature and 0.1C and 0.5C rates, respectively, with a capacity retention of 60.4% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 16.5 and 9.4 mA·h / g, respectively, with a capacity retention of 1.1% after 800 cycles at 0.5C and 42.1% at 3C compared to 0.1C.

[0148] Example 20

[0149] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0150] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0151] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0152] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is 1,3-dioxolane, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0153] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 62.0 and 51.4 mA·h / g at 0.1C and 0.5C rates at room temperature, respectively, with a capacity retention of 76.4% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 42.0 and 30.5 mA·h / g, respectively, with a capacity retention of 34.2% after 800 cycles at 0.5C and 44.1% at 3C compared to 0.1C.

[0154] Example 21

[0155] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0156] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0157] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0158] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 0.1 mol / L.

[0159] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. At room temperature, the discharge specific capacities at 0.1C and 0.5C rates were 92.1 and 89.5 mA·h / g, respectively, with a capacity retention of 91.1% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 90.0 and 88.6 mA·h / g, respectively, with a capacity retention of 93.2% after 800 cycles at 0.5C and 72.0% at 3C compared to 0.1C.

[0160] Example 22

[0161] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0162] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0163] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0164] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 3 vol%, and the concentration of the electrolyte is 1.5 mol / L.

[0165] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. At room temperature, the discharge specific capacities at 0.1C and 0.5C rates were 86.0 and 81.3 mA·h / g, respectively, with a capacity retention of 90.2% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 82.2 and 81.4 mA·h / g, respectively, with a capacity retention of 92.9% after 800 cycles at 0.5C and 70.1% at 3C compared to 0.1C.

[0166] Example 23

[0167] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0168] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0169] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0170] In this embodiment, the sodium salt of the electrolyte is sodium hexafluorophosphate, the solvent is diethylene glycol dimethyl ether, the additive is vinylene carbonate, the amount of the additive is 5 vol%, and the concentration of the electrolyte is 0.8 mol / L.

[0171] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. At room temperature, the discharge specific capacities at 0.1C and 0.5C rates were 98.3 and 92.5 mA·h / g, respectively, with a capacity retention of 90.1% at 3C compared to 0.1C. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 92.0 and 89.4 mA·h / g, respectively, with a capacity retention of 90.3% after 800 cycles at 0.5C and 71.1% at 3C compared to 0.1C.

[0172] Comparative Example 1

[0173] The low-temperature resistant sodium-ion battery provided in this embodiment includes a positive electrode, a negative electrode, and an electrolyte.

[0174] In this embodiment, the positive electrode is a circular sheet with a diameter of 10 mm. The active material used for the positive electrode is Na. 0.67 Ni 0.33 Mn 0.67 O2; the conductive additive in the positive electrode is Super-P; the binder used in the positive electrode is polyvinylidene fluoride; the positive current collector is aluminum foil. The ratio of positive active material, conductive additive, and binder in the positive electrode is 7.5:1.5:1, and the coating weight on the positive current collector is 1.5 mg / cm³. 2 .

[0175] In this embodiment, the negative electrode is a sodium foil disc with a diameter of 12 mm.

[0176] In this embodiment, the sodium salt of the electrolyte is sodium perchlorate, the solvent is propylene carbonate, the additive is fluoroethylene carbonate, the amount of the additive is 5 vol%, and the concentration of the electrolyte is 1 mol / L.

[0177] The aforementioned positive electrode, negative electrode, electrolyte, and a 16mm diameter glass fiber membrane separator from Whatman were assembled into a CR2032 coin cell in an argon-filled glove box, and their electrochemical performance was tested. The assembled cell exhibited discharge specific capacities of 86.1 mA·h / g at 0.1C and 0.5C rates at room temperature. At a low temperature of -30℃, the discharge specific capacities at 0.1C and 0.5C rates were 73.4 and 49.5 mA·h / g, respectively, and the cell became essentially inoperable at 1C rate.

[0178] By comparing the experimental results of the above comparative examples and multiple embodiments, it can be seen that sodium-ion batteries using Na... 0.7 Li 0.03 Mg0.03 Ni 0.27 Mn 0.6 Ti 0.07 When O2 is used as the positive electrode active material, Super-P as the positive electrode conductive agent, polyvinylidene fluoride as the positive electrode binder, and aluminum foil as the positive electrode current collector, combined with sodium foil negative electrode and sodium hexafluorophosphate combined with diethylene glycol dimethyl ether electrolyte, it exhibits optimal performance at low temperatures.

[0179] Furthermore, when the ratio of positive electrode active material, conductive additive, and binder is 7.5:1.5:1, the coating weight on the positive electrode current collector is 1.5 mg / cm³. 2 The low-temperature sodium-ion battery exhibits optimal performance when the electrolyte concentration is 0.8 mol / L, the solvent additive is vinylene carbonate, and the amount of additive is 3 vol%.

[0180] When the above conditions, i.e. the conditions of Example 1, are adopted, the discharge specific capacity of this low-temperature resistant sodium-ion battery at room temperature at 0.1C and 0.5C rates is 97.0 and 95.5 mA·h / g, respectively, and the capacity retention rate at 3C is 93.4% of that at 0.1C. When tested at a low temperature of -30°C, the discharge specific capacity at 0.1C and 0.5C rates is 92.7 and 91.4 mA·h / g, respectively, and the capacity retention rate after 800 cycles at 0.5C is 94.2%, and the capacity retention rate at 3C is 72.1% of that at 0.1C.

[0181] Compared with current commercial sodium-ion batteries and other common products, the low-temperature resistant sodium-ion battery proposed in this application shows significant low-temperature resistance and excellent electrochemical performance such as rate performance, cycle performance and discharge capacity in low-temperature environments without affecting room temperature performance.

[0182] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0183] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A low-temperature resistant sodium-ion battery, characterized in that, Includes positive electrode, negative electrode, and electrolyte; The positive electrode active material of the positive electrode sheet is Na. 0.7 Li 0.03 Mg 0.03 Ni 0.27 Mn 0.6 Ti 0.07 O2; wherein, the ratio of the positive electrode active material, conductive additive, and binder in the positive electrode sheet is 7~8.5:1~2:0.5~1; the coating weight of the positive electrode sheet on the positive electrode current collector is 0.9~3.5 mg / cm³. 2 ; The negative electrode active material of the negative electrode sheet is carbon or sodium foil; wherein, when the negative electrode active material of the negative electrode sheet is carbon, the ratio of the negative electrode active material, conductive additive and binder of the negative electrode sheet is 7.5~8:1~1.5:

1. The organic solvent of the electrolyte is a mixture of ethers and carbonates.

2. The low-temperature resistant sodium-ion battery according to claim 1, characterized in that, The ratio of the positive electrode active material, conductive additive, and binder in the positive electrode sheet is 7.5:1.5:

1.

3. The low-temperature resistant sodium-ion battery according to claim 1, characterized in that, The ratio of the negative electrode active material, conductive additive, and binder in the negative electrode sheet is 8:1:

1.

4. The low-temperature resistant sodium-ion battery according to claim 1 or 3, characterized in that, The coating weight of the negative electrode sheet on the negative electrode current collector is 0.4~1.6 mg / cm³. 2 .

5. The low-temperature resistant sodium-ion battery according to claim 1, characterized in that, The concentration of the electrolyte is 0.1~1.5 mol / L.

6. The low-temperature resistant sodium-ion battery according to claim 1 or 5, characterized in that, The organic solvent includes solvents and additives; The solvent includes at least one of the following: ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether; and / or the additive includes at least one of the following: fluoroethylene carbonate, vinylene carbonate, 1,3-dioxolane.

7. The low-temperature resistant sodium-ion battery according to claim 5, characterized in that, The amount of the additive is 3-5 vol.

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