A rapid screening method for low-temperature sodium-ion batteries and application thereof

Abstract

This invention relates to the field of sodium-ion battery technology, specifically to a rapid screening method for low-temperature sodium-ion batteries and its application. The method involves assembling positive electrode, negative electrode, separator, and electrolyte into different sodium-ion batteries, followed by charging and formation. Q-V data for each sodium-ion battery during the formation process are obtained, and dQ / dV-V curves are plotted to determine the peak position and area of ​​the redox peak. After formation, the sodium-ion batteries undergo aging and capacity testing to obtain finished sodium-ion batteries. Under low-temperature conditions, the finished sodium-ion batteries are subjected to DCR testing to obtain their low-temperature DCR resistance. Based on the peak position and area of ​​the redox peak and the low-temperature DCR resistance, the low-temperature performance of different sodium-ion batteries is determined. This method can quickly and accurately screen sodium-ion battery systems with relatively superior low-temperature performance, shortening the cell low-temperature performance testing cycle and improving the screening efficiency of low-temperature sodium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and more specifically, to a rapid screening method for low-temperature sodium-ion batteries and its application. Background Technology

[0002] Existing sodium-ion batteries exhibit better low-temperature discharge performance compared to lithium-ion batteries, but their low-temperature charging performance remains poor, resulting in poor low-temperature cycle performance. However, optimizing the structure and composition of the positive electrode, negative electrode, and electrolyte can improve the low-temperature performance of sodium-ion batteries.

[0003] Currently, screening the low-temperature performance differences of different sodium-ion batteries mainly involves comparing the cycle capacity retention and charge / discharge efficiency of the batteries under low-rate charge / discharge conditions at low temperatures. However, this method suffers from long testing cycles and low screening efficiency.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The primary objective of this invention is to provide a rapid screening method for low-temperature sodium-ion batteries. By analyzing the peak position and area of ​​the redox peaks in the dQ / dV-V curve and the low-temperature DCR resistance, the low-temperature performance of sodium-ion batteries in different systems can be quickly determined. This method shortens the low-temperature performance testing cycle of sodium-ion batteries and improves the screening efficiency of low-temperature sodium-ion batteries.

[0006] The second objective of this invention is to provide a rapid screening method for low-temperature sodium-ion batteries and its application in the preparation of sodium-ion batteries and electrical devices.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0008] This invention first provides a rapid screening method for low-temperature sodium-ion batteries, comprising the following steps: assembling a positive electrode, a negative electrode, a separator, and an electrolyte into different sodium-ion batteries; charging and forming each sodium-ion battery to obtain QV data during the formation process, and plotting a dQ / dV-V curve to obtain the peak position and peak area of ​​the redox peak; after the sodium-ion battery formation is completed, aging and capacity testing are performed to obtain a finished sodium-ion battery; under low-temperature conditions, a DCR test is performed on the finished sodium-ion battery to obtain its low-temperature DCR resistance value; based on the peak position and peak area of ​​the redox peak and the low-temperature DCR resistance value, the low-temperature performance of different sodium-ion batteries is determined.

[0009] Furthermore, the method for determining this includes: under the same formation conditions, the more the redox peak position shifts to the left and the smaller the peak area of ​​different sodium-ion batteries, the smaller the polarization of the formation film formation process; under the same low-temperature conditions, the smaller the low-temperature DCR resistance of different finished sodium-ion batteries, the smaller the electrochemical impedance and diffusion impedance of the finished sodium-ion battery; the smaller the polarization of the formation film formation process, the smaller the electrochemical impedance and diffusion impedance, the better the low-temperature cycle performance of the sodium-ion battery.

[0010] Furthermore, under the same formation conditions, first compare the peak positions of the redox peaks of different sodium-ion batteries, then compare the peak areas of the redox peaks of different sodium-ion batteries, and finally compare the low-temperature DCR resistance of different sodium-ion batteries. The specific method is as follows: First compare the peak positions of the redox peaks of different sodium-ion batteries. The more the peak position shifts to the left, the smaller the polarization during the formation film formation process, and the better the low-temperature cycle performance of the sodium-ion battery. When the peak positions of the redox peaks of different sodium-ion batteries are the same, compare... The smaller the peak area of ​​the redox peak of different sodium-ion batteries, the smaller the polarization of the formation film process, and the better the low-temperature cycling performance of the sodium-ion battery. When the redox peak positions of different sodium-ion batteries are the same and the peak areas of the redox peaks are similar, the low-temperature DCR resistance of different sodium-ion batteries is compared. The smaller the low-temperature DCR resistance, the smaller the electrochemical impedance and diffusion impedance of the sodium-ion battery at low temperature, and the better the low-temperature cycling performance of the sodium-ion battery.

[0011] Furthermore, the formation is carried out in an environment of 20~50°C.

[0012] Furthermore, the current generated is not higher than 0.5C.

[0013] Furthermore, the formation temperature is 25°C, and the formation current is 0.1C.

[0014] Furthermore, the temperature of the low-temperature condition is below 0°C.

[0015] Furthermore, the temperature of the low-temperature condition is -20°C.

[0016] Furthermore, the positive electrode active material in the positive electrode sheet includes a layered oxide positive electrode material.

[0017] Furthermore, the negative electrode active material in the negative electrode sheet includes at least one of graphite and hard carbon.

[0018] Furthermore, the electrolyte includes carbonate-based electrolytes.

[0019] The present invention also provides the application of the above-mentioned rapid screening method for low-temperature sodium-ion batteries in the preparation of sodium-ion batteries and electrical devices.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The rapid screening method for low-temperature sodium-ion batteries provided by this invention obtains the polarization differences in the formation film-forming process by comparing the peak positions and peak areas of the redox peaks of the dQ / dV-V curves of different sodium-ion battery systems during the formation process. By comparing the DCR test results of different sodium-ion battery systems under low-temperature conditions, the differences in electrochemical impedance and diffusion impedance of the batteries at low temperatures are obtained. Among them, the smaller the polarization of the battery formation film-forming process, the lower the low-temperature DCR resistance, the lower the charge transfer impedance and diffusion impedance of sodium ions passing through the SEI film to reach the bulk phase of the material under low-temperature conditions, the better the low-temperature charge-discharge cycle performance of the battery, and the higher the low-temperature charge-discharge cycle capacity retention rate. This method shortens the low-temperature performance testing cycle of the battery cell and improves the screening efficiency of low-temperature sodium-ion batteries.

[0022] (2) The rapid screening method for low-temperature sodium-ion batteries provided by the present invention can quickly and accurately screen out sodium-ion battery systems with relatively better low-temperature performance. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 The dQ / dV-V curves of Examples 1-6 and Comparative Example 1 provided by the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0026] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0027] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0028] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0029] In a first aspect, the present invention provides a rapid screening method for low-temperature sodium-ion batteries, comprising the following steps:

[0030] After assembling the positive electrode, negative electrode, separator, and electrolyte into different sodium-ion batteries, each sodium-ion battery is charged and formed.

[0031] Specifically, positive and negative electrode plates of different systems are selected, separated by a separator, and assembled into a bare battery. The bare battery is then installed in a battery casing to obtain a dry cell ready for electrolyte injection. Next, electrolytes of different systems are selected, injected into the dry cell, and sealed for settling. After settling, the charging and formation process is performed.

[0032] QV data for each sodium-ion battery during the formation process were obtained, and dQ / dV-V curves were plotted to obtain the peak positions and peak areas of the redox peaks. Specifically, QV data for sodium-ion batteries of different systems during the formation process were collected, and dQ / dV-V curves were plotted based on the QV data to obtain the peak positions and peak areas of the redox peaks in the dQ / dV-V curves.

[0033] The sodium-ion battery, after formation, undergoes aging and capacity testing to obtain a finished sodium-ion battery. The finished sodium-ion battery is then subjected to a low-temperature DCR test to obtain its low-temperature DCR resistance value. In other words, the finished battery is subjected to a DCR test under low-temperature conditions to obtain its resistance information at low temperatures.

[0034] The low-temperature performance of different sodium-ion batteries can be judged based on the peak position and peak area of ​​the redox peak in the dQ / dV-V formation curve and the low-temperature DCR resistance.

[0035] This invention provides a rapid screening method for low-temperature sodium-ion batteries. It obtains the polarization differences during the formation process by comparing the peak positions and areas of the redox peaks in the dQ / dV-V curves of different sodium-ion battery systems. Furthermore, it obtains the differences in electrochemical impedance and diffusion impedance at low temperatures by comparing the DCR test results of different sodium-ion battery systems under low-temperature conditions. It is understood that for different sodium-ion battery systems, the smaller the polarization during formation, the lower the low-temperature DCR resistance. This results in lower charge transfer resistance and diffusion resistance for sodium ions passing through the SEI film to reach the bulk phase of the material under low-temperature conditions, leading to better low-temperature charge-discharge cycle performance and higher capacity retention. This method shortens the low-temperature performance testing cycle of the battery cells and improves the screening efficiency of low-temperature sodium-ion batteries.

[0036] In some specific embodiments, the method for judgment includes: under the same formation conditions, the more the redox peak position shifts to the left and the smaller the peak area of ​​different sodium-ion batteries, the smaller the polarization of the formation film formation process; under the same low-temperature conditions, the smaller the low-temperature DCR resistance of different finished sodium-ion batteries, the smaller the electrochemical impedance and diffusion impedance of the finished sodium-ion battery; the smaller the polarization of the formation film formation process, the smaller the electrochemical impedance and diffusion impedance, the better the low-temperature cycle performance of the sodium-ion battery. The synergistic effect of these two factors influences the low-temperature performance of the battery; therefore, the low-temperature performance of the battery can be judged based on the dQ / dV-V curve and the low-temperature DCR resistance.

[0037] In some specific implementations, under the same formation conditions, the peak positions of the redox peaks of different sodium-ion batteries are compared first, followed by the peak areas of the redox peaks, and finally the low-temperature DCR resistance of different sodium-ion batteries. That is, the method of judgment is to first determine the peak position; the further left the peak position shifts, the smaller the SEI film polarization. When the peak positions are close, the peak area is then determined; the smaller the peak area, the better the SEI film uniformity and the lower the impedance. When both the peak position and peak area are close, the low-temperature DCR resistance is compared; the smaller the low-temperature DCR resistance, the smaller the electrochemical impedance and diffusion impedance of the battery under low-temperature conditions. In the low-temperature cycling process, SEI film polarization is the dominant factor, so peak position is determined first, followed by low-temperature DCR.

[0038] The specific judgment method is as follows: Under the same formation conditions, first compare the peak positions of the redox peaks of different sodium-ion batteries. The more the peak position shifts to the left, the smaller the polarization of the formation film formation process, and the better the low-temperature cycle performance of the sodium-ion battery. When the peak positions of the redox peaks of different sodium-ion batteries are the same, compare the peak areas of the redox peaks of different sodium-ion batteries. The smaller the peak area, the smaller the polarization of the formation film formation process, and the better the low-temperature cycle performance of the sodium-ion battery. When the peak positions of the redox peaks of different sodium-ion batteries are the same and the peak areas of the redox peaks of different sodium-ion batteries are similar, compare the low-temperature DCR resistance of different sodium-ion batteries. The smaller the low-temperature DCR resistance, the smaller the electrochemical impedance and diffusion impedance of the sodium-ion battery at low temperature, and the better the low-temperature cycle performance of the sodium-ion battery.

[0039] In some specific embodiments, the formation is carried out in an environment of 20~50°C, such as 25°C, 30°C, 35°C, 40°C or 45°C.

[0040] In some specific implementations, the current generated is not higher than 0.5C, for example 0.4C, 0.3C, 0.2C or 0.1C.

[0041] In some specific embodiments, the formation temperature is 25°C and the formation current is 0.1°C.

[0042] In some specific embodiments, the temperature of the low-temperature condition is below 0°C, for example -5°C, -10°C, -15°C, or -20°C.

[0043] In some specific embodiments, the temperature of the low-temperature condition is -20°C.

[0044] In some specific embodiments, the positive electrode active material in the positive electrode sheet includes a layered oxide positive electrode material.

[0045] In some specific embodiments, the negative electrode active material in the negative electrode sheet includes at least one of graphite and hard carbon.

[0046] In some specific embodiments, the electrolyte includes a carbonate-based electrolyte.

[0047] In some specific implementations, low-temperature cycling tests are performed on finished sodium-ion batteries. The low-temperature cycle capacity retention and low-temperature cycle life information obtained from these tests are used to verify the low-temperature performance of the sodium-ion batteries. The low-temperature cycling test conditions refer to 0.1C charge-discharge cycles at -20°C, with the upper and lower voltage limits determined based on the sodium-ion battery system.

[0048] Secondly, the present invention provides the application of the rapid screening method for low-temperature sodium-ion batteries in the preparation of sodium-ion batteries and electrical devices.

[0049] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0050] Example 1

[0051] (1) Preparation of negative electrode sheet: according to the mass percentage of negative electrode active material: conductive agent: binder = 95%: 1.5%: 3.5% (the negative electrode active material is hard carbon, D50 = 5.5μm, BET = 9m) 2 The negative electrode slurry was prepared using NMP as the solvent (7 mg / cm³). The conductive agent was conductive carbon black, and the binder was PVDF. 2 The surface density is applied to the negative electrode current collector, dried in a coating oven, then the electrode sheet is compacted by a roller press, and finally the required negative electrode sheet is obtained after slitting and die cutting.

[0052] (2) Preparation of the positive electrode sheet: According to the mass percentage of positive active material: conductive agent: binder = 96%: 2%: 2% (the positive active material is a layered oxide positive electrode material, and its chemical formula is Na) 0.46 Cu 0.32 Mn 0.68 The positive electrode slurry was prepared using O2; conductive agent was conductive carbon black; binder was PVDF, and the solvent was NMP. The positive electrode slurry was prepared at a concentration of 17 mg / cm³. 2 The surface density is applied to the positive electrode current collector, dried in a coating oven, then the electrode sheet is compacted by a roller press, and finally the required positive electrode sheet is obtained after slitting and die cutting.

[0053] (3) Preparation of finished battery: The ambient temperature is controlled at 25±5℃, the humidity is ≤10%RH, and the cleanliness is 100,000 level. The positive and negative electrode sheets prepared above are assembled with the separator into a bare battery. The bare battery is subjected to a short circuit test. The qualified bare battery is installed into the battery shell and sealed. After baking in an oven, the electrolyte is injected (the injected electrolyte is Zhongke Haina HNE400R001, which is a carbonate electrolyte). After static aging treatment, charging and formation are carried out. The formation current is 0.1C and the formation temperature is 45℃. The dQ / dV-V curve data during the formation process are collected to obtain the peak position and peak area of ​​the redox peak. Finally, after static aging and capacity testing, a finished sodium-ion battery with charge and discharge characteristics is obtained.

[0054] (4) DCR test: The DCR test was performed on the finished sodium-ion battery at 50% SOC under -20℃ conditions. The DCR test procedure was to discharge at 0.1C for 30s. The low-temperature DCR resistance of the finished sodium-ion battery was obtained based on the voltage and current changes during the discharge process.

[0055] (5) Low temperature cycle test: The finished sodium-ion battery was cycle tested at -20℃ with a charge-discharge rate of 0.1C and upper and lower limit voltages of 2-3.95V to obtain the cycle life and cycle capacity retention rate.

[0056] Example 2

[0057] This embodiment is basically the same as Embodiment 1, except that: in step (1), the BET of hard carbon is 10m. 2 / g.

[0058] Example 3

[0059] This embodiment is basically the same as Embodiment 1, except that: in step (1), the BET of hard carbon is 11m. 2 / g.

[0060] Example 4

[0061] This embodiment is basically the same as Embodiment 1, except that: in step (1), the hard carbon has a D50 of 5 μm and a BET of 7 m. 2 / g.

[0062] Example 5

[0063] This embodiment is basically the same as Embodiment 1, except that: in step (1), the hard carbon has a D50 of 5 μm and a BET of 9 m. 2 / g.

[0064] Example 6

[0065] This embodiment is basically the same as Embodiment 1, except that: in step (1), the hard carbon has a D50 of 5 μm and a BET of 12 m. 2 / g.

[0066] Example 7

[0067] This embodiment is basically the same as embodiment 1, except that the electrolyte injected in step (3) is Zhongke Haina HNE400R002.

[0068] Comparative Example 1

[0069] This comparative example is basically the same as Example 1, except that the hard carbon in step (1) has a D50 of 6 μm and a BET of 7 m. 2 / g.

[0070] For the dQ / dV-V curves of Examples 1-7 and Comparative Example 1, please refer to [the original text]. Figure 1 As shown.

[0071] The peak positions and peak areas of the redox peaks and the low-temperature DCR resistance results in the dQ / dV-V curves of Examples 1-7 and Comparative Example 1 are shown in Table 1 below.

[0072] Table 1. Peak positions and areas of redox peaks in sodium-ion batteries and low-temperature DCR results.

[0073]

[0074] From Table 1 and Figure 1 The peak positions and peak areas of the redox peaks in the samples show that, compared with Comparative Example 1, the peak positions of each group of examples are relatively lower, and the redox peaks in the dQ / dV-V curves shift to the left, indicating that the polarization during the SEI film formation process is relatively smaller. When the peak positions are the same, as in the comparison between Examples 2 and 3, and Examples 4 and 6, the smaller the peak area, the better the uniformity of the film formation process, which is beneficial for reducing the overall impedance of the SEI film.

[0075] Meanwhile, as shown in Table 1, the low-temperature DCR data of each group of examples are relatively lower than those of Comparative Example 1. This indicates that under low-temperature conditions, the charge transfer resistance and diffusion resistance of sodium ions passing through the SEI film to reach the bulk phase of the material are lower, which is beneficial to the insertion and extraction of sodium ions during low-temperature charge-discharge cycles. During low-temperature cycling, the film formation polarization of the SEI film is dominant. Therefore, the formation peak position is determined first, and then the low-temperature DCR difference is determined. For example, comparing Examples 4 and 5, when the peak position and peak area are similar, the low-temperature DCR of Example 5 is significantly lower, and its impedance during low-temperature charge-discharge processes is relatively smaller, thus its low-temperature performance is relatively better.

[0076] The polarization of the SEI film, as well as the synergistic effect of charge transfer impedance and diffusion impedance, affect the low-temperature cycling performance of the battery. Therefore, it can be determined that the low-temperature cycling performance of the six systems in Examples 1 to 7 is better than that of the system in Comparative Example 1. Based on the specific data, the order of low-temperature cycling performance from low to high can be further determined as follows: Comparative Example 1 < Example 1 < Example 2 < Example 3 < Example 4 < Example 5 < Example 6 < Example 7.

[0077] The low-temperature charge-discharge cycle data of Examples 1-7 and Comparative Example 1 are shown in Table 2.

[0078] Table 2 Low-temperature charge-discharge cycle data of sodium-ion batteries of different systems

[0079]

[0080] In Example 4, after 16 cycles of low-temperature cycling, the capacity retention rate was close to 90%; in Example 5, after 19 cycles of low-temperature cycling, the capacity retention rate was close to 90%, meaning that the low-temperature cycling life of Example 5 was better than that of Example 4, with a longer number of cycles. Examples 6 and 7 only recorded data up to 25 cycles, because the testing time was longer, and the capacity retention rate at 25 cycles was already significantly improved.

[0081] As can be seen from the low-temperature charge-discharge cycle data of sodium-ion batteries of different systems in Table 2, the order of low-temperature cycle life from low to high is: Comparative Example 1 < Example 1 < Example 2 < Example 3 < Example 4 < Example 5 < Example 6 < Example 7. The results are consistent with the above judgment results based on the peak position and peak area of ​​the redox peak and the low-temperature DCR resistance, thus verifying the accuracy of the above conclusions.

[0082] Therefore, by comparing the redox peak information of the formation dQ / dV-V curves and the low-temperature DCR resistance information of sodium-ion batteries of different systems, this invention can quickly and accurately screen out sodium-ion battery systems with relatively better low-temperature performance, shorten the cell low-temperature performance testing cycle, and improve the screening efficiency of low-temperature sodium-ion batteries.

[0083] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can 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, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A rapid screening method for low-temperature sodium-ion batteries, characterized in that, Includes the following steps: After assembling the positive electrode, negative electrode, separator and electrolyte into different sodium-ion batteries, each sodium-ion battery is charged and formed to obtain the QV data of each sodium-ion battery during the formation process, and a dQ / dV-V curve is plotted to obtain the peak position and peak area of ​​the redox peak. After the sodium-ion battery undergoes aging and capacity testing following the completion of the formation process, a finished sodium-ion battery is obtained. The finished sodium-ion battery is then subjected to a DCR test under low-temperature conditions to obtain its low-temperature DCR resistance value. The low-temperature performance of different sodium-ion batteries can be judged based on the peak position and peak area of ​​the redox peak and the low-temperature DCR resistance. The method for determining the polarization includes: under the same formation conditions, the more the redox peak position shifts to the left and the smaller the peak area of ​​different sodium-ion batteries, the smaller the polarization of the formation film formation process; under the same low-temperature conditions, the smaller the low-temperature DCR resistance of different finished sodium-ion batteries, the smaller the electrochemical impedance and diffusion impedance of the finished sodium-ion battery; the smaller the polarization of the formation film formation process, the smaller the electrochemical impedance and diffusion impedance, the better the low-temperature cycle performance of the sodium-ion battery. Under the same formation conditions, the peak positions of the redox peaks of different sodium-ion batteries are compared first. The more the peak position shifts to the left, the smaller the polarization of the formation film formation process, and the better the low-temperature cycle performance of the sodium-ion battery. When the redox peaks of different sodium-ion batteries are at the same position, the peak areas of the redox peaks of different sodium-ion batteries are compared. The smaller the peak area, the smaller the polarization of the formation film process, and the better the low-temperature cycle performance of the sodium-ion battery. When the redox peaks of different sodium-ion batteries have the same position and similar peak areas, the low-temperature DCR resistance of the different sodium-ion batteries is compared. The smaller the low-temperature DCR resistance, the smaller the electrochemical impedance and diffusion impedance of the sodium-ion battery at low temperature, and the better the low-temperature cycle performance of the sodium-ion battery.

2. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The formation was carried out at 20~50℃.

3. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The current of the formation is not higher than 0.5C.

4. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The formation temperature is 25°C.

5. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The current generated is 0.1C.

6. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The temperature under the low-temperature condition is below 0°C.

7. The rapid screening method for low-temperature sodium-ion batteries according to claim 6, characterized in that, The temperature of the low-temperature condition is -20℃.

8. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The positive electrode active material in the positive electrode sheet includes a layered oxide positive electrode material; And / or, the negative electrode active material in the negative electrode sheet includes at least one of graphite and hard carbon.

9. The rapid screening method for low-temperature sodium-ion batteries according to claim 1, characterized in that, The electrolyte includes carbonate-based electrolytes.

10. The application of the rapid screening method for low-temperature sodium-ion batteries as described in any one of claims 1 to 9 in the preparation of sodium-ion batteries and electrical devices.

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