Rapid screening method for low-temperature sodium-ion batteries and application of rapid screening method

Abstract

The invention relates to the technical field of sodium-ion batteries, in particular to a rapid screening method for low-temperature sodium-ion batteries and application of the rapid screening method. Assembling the positive plate, the negative plate, the diaphragm and the electrolyte into different sodium ion batteries, performing charging formation to obtain Q-V data of each sodium ion battery in the formation process, and drawing a dQ / dV-V curve graph to obtain the peak position and the peak area of the redox peak; aging and grading the formed sodium-ion battery to obtain a finished sodium-ion battery; under a low-temperature condition, performing DCR test on the finished sodium-ion battery to obtain a low-temperature DCR resistance value of the finished sodium-ion battery; according to the peak position and the peak area of the redox peak and the low-temperature DCR resistance value, the low-temperature performance of different sodium-ion batteries is judged. According to the method, the sodium-ion battery system with relatively excellent low-temperature performance can be quickly and accurately screened out, the test period of the low-temperature performance of the battery cell is shortened, and the screening efficiency of the low-temperature sodium-ion battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium-ion batteries, and in particular, to a rapid screening method for low-temperature sodium-ion batteries and its applications. Background Art

[0002] Existing sodium-ion batteries have relatively better low-temperature discharge performance compared to lithium-ion batteries, but their low-temperature charging performance is still poor, resulting in poor low-temperature cycle performance of sodium-ion batteries. By optimizing the structural compositions of the positive electrode, negative electrode, and electrolyte, the low-temperature performance of sodium-ion batteries can be improved.

[0003] Currently, to screen the differences in low-temperature performance of different sodium-ion batteries, mainly the cycle capacity retention rate and charge-discharge efficiency of the batteries are compared during low-rate charge and discharge under low-temperature conditions, which has the problems of a long test period and low screening efficiency.

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

[0005] The first object of the present invention is to provide a rapid screening method for low-temperature sodium-ion batteries. Through the peak positions and peak areas of the oxidation-reduction peaks in the dQ / dV-V curve and the low-temperature DCR resistance value, the low-temperature performance of sodium-ion batteries in different systems can be quickly judged. This method shortens the low-temperature performance test period of sodium-ion batteries and improves the screening efficiency of low-temperature sodium-ion batteries.

[0006] The second object of the present invention is to provide the application of the rapid screening method for low-temperature sodium-ion batteries in the preparation of sodium-ion batteries and electrical equipment.

[0007] To achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0008] The present invention first provides a rapid screening method for low-temperature sodium-ion batteries, including the following steps: After assembling a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte into different sodium-ion batteries, each of the sodium-ion batteries is subjected to charge formation to obtain Q-V data of each sodium-ion battery during the formation process, and a dQ / dV-V curve graph is made to obtain the peak positions and peak areas of the oxidation-reduction peaks; the sodium-ion batteries after the formation is completed are aged and divided into capacities to obtain finished sodium-ion batteries; under low-temperature conditions, a DCR test is performed on the finished sodium-ion batteries to obtain the low-temperature DCR resistance values of the finished sodium-ion batteries; according to the peak positions and peak areas of the oxidation-reduction peaks and the low-temperature DCR resistance values, the low-temperature performance of different sodium-ion batteries is judged.

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

[0010] Further, 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 resistances 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 of the formation film-forming 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-forming 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 resistances 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.

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

[0012] Further, the current of the formation is not higher than 0.5C.

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

[0014] Further, the temperature of the low-temperature conditions is lower than 0 °C.

[0015] Further, the temperature of the low-temperature conditions is -20 °C.

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

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

[0018] Further, the electrolyte includes a carbonate-based electrolyte.

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

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

[0021] (1) For the rapid screening method for low-temperature sodium-ion batteries provided by the present invention, by comparing the peak positions and peak areas of the oxidation-reduction peaks of the dQ / dV-V curves during the formation process of sodium-ion batteries with different systems, the polarization differences during the formation film-forming process are obtained. By comparing the DCR test results of sodium-ion batteries with different systems under low-temperature conditions, the differences in the electrochemical impedance and diffusion impedance of the batteries at low temperature are obtained. Among them, the smaller the polarization of the battery formation film-forming process, the lower the low-temperature DCR resistance value, the lower the charge transfer impedance and diffusion impedance for sodium ions to penetrate 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 retention rate of the low-temperature charge-discharge cycle capacity. This method shortens the test cycle of the low-temperature performance of the battery core 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. Description of the Drawings

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a graph of the formation dQ / dV-V curves of Examples 1 to 6 and Comparative Example 1 provided by the present invention. Detailed Embodiments

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0026] Unless otherwise specified, in the present invention, "first aspect", "second aspect", "third aspect", "fourth aspect", etc. are only for descriptive purposes 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, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on quantity.

[0027] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present invention are open-ended and can also be closed-ended. For example, the said "comprising" and "including" can mean that other components not listed can also be included or contained, or it can only include or contain the listed components.

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

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

[0030] After assembling a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte into different sodium-ion batteries, charge and formation are performed on each of the sodium-ion batteries.

[0031] Specifically, positive electrode sheets and negative electrode sheets of different systems are selected, separated by a separator in the middle, assembled into a bare battery, and then the bare battery is placed into a battery case to obtain a dry battery to be filled with electrolyte. Then, electrolytes of different systems are selected, injected into the dry battery, sealed and left standing. After the standing is completed, the charge and formation are performed.

[0032] Q-V data of each of the sodium-ion batteries during the formation process is obtained, and a dQ / dV-V curve graph is made to obtain the peak position and peak area of the redox peak. That is, Q-V data during the formation process of sodium-ion batteries of different systems is collected, and a dQ / dV-V curve graph is made according to the Q-V data to obtain the peak position and peak area information of the redox peak in the dQ / dV-V curve graph.

[0033] The sodium-ion battery after the formation is aged and capacity-fractionated to obtain a finished sodium-ion battery; under low-temperature conditions, a DCR test is performed on the finished sodium-ion battery to obtain the low-temperature DCR resistance value of the finished sodium-ion battery. That is, under low-temperature conditions, a DCR test is performed on the finished battery to obtain the resistance value information of the finished sodium-ion battery under low-temperature conditions.

[0034] Based on the peak positions and peak areas of the oxidation-reduction peaks in the dQ / dV-V curve during formation and the low-temperature DCR resistance value, the low-temperature performance of different sodium-ion batteries is judged.

[0035] The rapid screening method for low-temperature sodium-ion batteries provided by the present invention obtains the polarization difference in the film formation process during formation by comparing the peak positions and peak areas of the oxidation-reduction peaks in the dQ / dV-V curve of different sodium-ion battery systems during formation, and obtains the differences in the electrochemical impedance and diffusion impedance of the batteries at low temperature by comparing the DCR test results of different sodium-ion battery systems under low-temperature conditions. It can be understood that for different sodium-ion battery systems, the smaller the polarization of the battery film formation process during formation and the lower the low-temperature DCR resistance value, the lower the charge transfer impedance and diffusion impedance for sodium ions to reach the bulk phase of the material under low-temperature conditions, and the relatively 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 test cycle of the battery cells and improves the screening efficiency of low-temperature sodium-ion batteries.

[0036] In some specific embodiments, the judgment method includes: under the same formation conditions, the more the peak positions of the oxidation-reduction peaks of different sodium-ion batteries shift to the left and the smaller the peak areas, the smaller the polarization of the film formation process during formation; under the same low-temperature conditions, the smaller the low-temperature DCR resistance value of different finished sodium-ion batteries, the smaller the electrochemical impedance and diffusion impedance of the finished sodium-ion batteries; the smaller the polarization of the film formation process during formation and the smaller the electrochemical impedance and diffusion impedance, the better the low-temperature cycle performance of the sodium-ion battery. The two act synergistically to affect the low-temperature performance of the battery, so the low-temperature performance of the battery can be judged according to the dQ / dV-V curve and the low-temperature DCR resistance value.

[0037] In some specific embodiments, under the same formation conditions, first compare the peak positions of the oxidation-reduction peaks of different sodium-ion batteries, then compare the peak areas of the oxidation-reduction peaks of different sodium-ion batteries, and finally compare the low-temperature DCR resistance values of different sodium-ion batteries. That is, the judgment method is to first judge the peak position. The more the peak position shifts to the left, the smaller the polarization of the SEI film formation. When the peak positions are close, then judge the peak area. The smaller the peak area, the better the film formation uniformity of the SEI film and the smaller the impedance. When the peak positions and peak areas are both close, compare the low-temperature DCR resistance value. The smaller the low-temperature DCR resistance value, the smaller the electrochemical impedance and diffusion impedance of the battery under low-temperature conditions. Among them, during the low-temperature cycle process, the polarization of the SEI film is the dominant factor, so the peak position is judged first, and then the low-temperature DCR is judged.

[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-forming process, and the better the low-temperature cycling 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-forming process, and the better the low-temperature cycling 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 resistances 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 cycling 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 embodiments, the current of the formation is not higher than 0.5C, such as 0.4C, 0.3C, 0.2C or 0.1C.

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

[0042] In some specific embodiments, the temperature of the low-temperature condition is lower than 0°C, such as -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 active material in the positive electrode sheet includes a layered oxide positive electrode material.

[0045] In some specific embodiments, the negative 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 embodiments, the low-temperature performance of the sodium-ion battery is verified by performing a low-temperature cycling test on the finished sodium-ion battery and based on the low-temperature cycling capacity retention rate and low-temperature cycling life information obtained from the low-temperature cycling test. Among them, the low-temperature cycling test conditions refer to charge and discharge cycling at 0.1C under the condition of -20°C, and the upper and lower limit voltages are determined according to the sodium-ion battery system.

[0048] In a second aspect, the present invention provides an application of the rapid screening method of the low-temperature sodium-ion battery in the preparation of sodium-ion batteries and electrical equipment.

[0049] The following will describe the embodiments of the present invention in detail in conjunction with the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0050] Example 1

[0051] (1) Preparation of the negative electrode sheet: Prepare a negative electrode slurry 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 = 5.5 μm, BET = 9 m 2 / g; the conductive agent is conductive carbon black; the binder is PVDF), where the solvent is NMP. Coat the negative electrode slurry on the negative electrode current collector at a surface density of 7 mg / cm 2 . After drying in a coating oven, the electrode sheet is compacted by a roll press, and finally, after slitting and die-cutting, the required negative electrode sheet can be obtained;

[0052] (2) Preparation of the positive electrode sheet: Prepare a positive electrode slurry according to the mass percentage of positive electrode active material: conductive agent: binder = 96%: 2%: 2% (the positive electrode active material is a layered oxide positive electrode material, and its chemical formula is Na 0.46 Cu 0.32 Mn 0.68 O 2 ; the conductive agent is conductive carbon black; the binder is PVDF), where the solvent is NMP. Coat the positive electrode slurry on the positive electrode current collector at a surface density of 17 mg / cm 2 . After drying in a coating oven, the electrode sheet is compacted by a roll press, and finally, after slitting and die-cutting, the required positive electrode sheet can be obtained;

[0053] (3) Preparation of the finished battery: Control the environmental temperature at 25 ± 5 °C, humidity ≤ 10% RH, and cleanliness at 100,000 levels. Assemble the positive electrode sheet, negative electrode sheet, and separator prepared above into a bare battery. Conduct a short-circuit test on the bare battery. Install the qualified bare battery into the battery case for encapsulation. After baking in an oven, inject the electrolyte (the injected electrolyte is the Zhongke Haina HNE400R001 model, which is a carbonate-based electrolyte). Then, after static aging treatment, perform charging formation. The formation current is 0.1C, and the formation temperature is 45 °C. Collect the dQ / dV-V curve data during the formation process to obtain the peak position and peak area of the redox peak. Finally, after static aging and grading processes, a finished sodium-ion battery with charge-discharge characteristics is obtained;

[0054] (4) DCR test: At -20°C, the DCR test was carried out on the finished sodium-ion battery at 50% SOC. The DCR test process was to discharge at 0.1C for 30 s, and the low-temperature DCR resistance value of the finished sodium-ion battery was obtained according to the voltage and current changes during the discharge process.

[0055] (5) Low-temperature cycle test: At -20°C, the cycle test was carried out on the finished sodium-ion battery. The charge-discharge rate was 0.1C, and the upper and lower limit voltages were 2 - 3.95V to obtain the cycle life and cycle capacity retention rate.

[0056] Example 2

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

[0058] Example 3

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

[0060] Example 4

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

[0062] Example 5

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

[0064] Example 6

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

[0066] Example 7

[0067] This example is basically the same as Example 1, except that: in step (3), the electrolyte noted is the Zhongke Haina HNE400R002 model.

[0068] Comparative Example 1

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

[0070] The dQ / dV-V curves of formation for Examples 1 to 7 and Comparative Example 1 are shown in Figure 1 the following figure.

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

[0072] Table 1 Peak positions, peak areas of the redox peaks, and low-temperature DCR results of each sodium-ion battery

[0073]

[0074]

[0075] From Table 1 and Figure 1 the data of the peak positions and peak areas of the redox peaks in the formation, it can be seen 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 curve shift to the left, indicating that the polarization during the SEI film formation process is relatively smaller. When the peak positions are the same, such as the comparison between Example 2 and Example 3, and the comparison between Example 4 and Example 6, the smaller the peak area, the better the uniformity of the film formation process, which is beneficial to reducing the overall impedance of the SEI film.

[0076] At the same time, from the low-temperature DCR data in Table 1, it can be seen that compared with Comparative Example 1, the low-temperature DCR resistance values of each group of examples are relatively lower, indicating that under low-temperature conditions, the charge transfer resistance and diffusion resistance of sodium ions passing through the SEI film to reach the material bulk phase are lower, which is beneficial to the insertion and extraction processes of sodium ions during low-temperature charge and discharge cycles. During the low-temperature cycling process, the film formation polarization of the SEI film dominates. Therefore, first judge the peak position of the formation film formation peak, and then judge the low-temperature DCR difference. For example, when comparing Example 4 and Example 5, when the peak positions and peak areas are close, the low-temperature DCR of Example 5 is significantly lower, and its impedance during low-temperature charge and discharge is relatively smaller. Therefore, its low-temperature performance is relatively better.

[0077] The polarization of the SEI film, as well as the charge transfer resistance and diffusion resistance, jointly affect the low-temperature cycling performance of the battery. It can be judged from this that the low-temperature cycling performance of the six groups of systems of Examples 1 to 7 is better than that of the system of Comparative Example 1. Based on the specific data, it can be further judged that the ranking of the low-temperature cycling performance from low to high is: Comparative Example 1 < Example 1 < Example 2 < Example 3 < Example 4 < Example 5 < Example 6 < Example 7.

[0078] The low-temperature charge and discharge cycle data of Examples 1 to 7 and Comparative Example 1 are shown in Table 2.

[0079] Table 2 Low-temperature charge and discharge cycle data of sodium-ion batteries with different systems

[0080] Group Number of low-temperature cycles Capacity retention rate Example 1 10 90.22％ Example 2 12 90.61％ Example 3 14 90.44％ Example 4 16 90.64％ Example 5 19 90.30％ Example 6 25 93.90％ Example 7 25 97.63％ Comparative Example 1 7 90.04％

[0081] Among them, after 16 cycles of low-temperature cycling in Example 4, the capacity retention rate < 90%; after 19 cycles of low-temperature cycling in Example 5, the capacity retention rate < 90%, that is, the low-temperature cycling life of Example 5 is better than that of Example 4, and the number of cycling is longer. Only the data of 25 cycles were recorded for Example 6 and Example 7. Because the test time is long, the capacity retention rate at 25 cycles has been significantly improved.

[0082] From the low-temperature charge-discharge cycling data of sodium-ion batteries with different systems in Table 2, it can be seen that the low-temperature cycling life is sorted from low to high as follows: Comparative Example 1 < Example 1 < Example 2 < Example 3 < Example 4 < Example 5 < Example 6 < Example 7. The result is consistent with the above judgment results through the peak position and peak area of the redox peak and the low-temperature DCR resistance value, verifying the accuracy of the above conclusion.

[0083] It can be seen therefrom that by comparing the redox peak information of the formation dQ / dV-V curve and the low-temperature DCR resistance value information of sodium-ion batteries with different systems, the present invention can quickly and accurately screen out the sodium-ion battery system with relatively better low-temperature performance, shorten the low-temperature performance test cycle of the battery cell, and improve the screening efficiency of low-temperature sodium-ion batteries.

[0084] Although the present invention has been illustrated and described with reference to specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions described in the foregoing embodiments may be modified, or some or all of the technical features may be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications 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: The steps include: After assembling the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte into different sodium ion batteries, charging and forming each of the sodium ion batteries, obtaining the QV data of each of the sodium ion batteries during the formation process, and making a dQ / dV-V curve to obtain the peak position and peak area of ​​the redox peak; After the sodium ion battery has been formed, it is aged and divided into different capacities to obtain a finished sodium ion battery; under low temperature conditions, the finished sodium ion battery is subjected to a DCR test to obtain a low temperature DCR resistance value of the finished sodium ion battery; The low-temperature performance of different sodium-ion batteries is judged based on the peak position and peak area of ​​the redox peak and the low-temperature DCR resistance.

2. The rapid screening method for low-temperature sodium ion batteries according to claim 1, characterized in that: The judgment method includes: under the same formation conditions, the more the peak position of the redox peak of different sodium ion batteries shifts to the left and the smaller the peak area, the smaller the polarization of the formation and film forming 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 and film forming process, the smaller the electrochemical impedance and diffusion impedance, the better the low-temperature cycle performance of the sodium ion battery.

3. The rapid screening method for low-temperature sodium ion batteries according to claim 2, characterized in that: Under the same formation conditions, first compare the peak positions of the redox peaks of the different sodium ion batteries. The more the peak position shifts to the left, the smaller the polarization of the formation film forming process is, and the better the low-temperature cycle performance of the sodium ion battery is. When the peak positions of the redox peaks of different sodium ion batteries are the same, 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 forming 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, the low-temperature DCR resistance values ​​of the different sodium ion batteries are compared. The smaller the low-temperature DCR resistance value, 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.

4. The rapid screening method for low-temperature sodium ion batteries according to claim 1, characterized in that: The formation is carried out at 20-50°C; And / or, the formation current is not higher than 0.5C.

5. The rapid screening method for low-temperature sodium ion batteries according to claim 4, characterized in that: The formation temperature is 25° C., and the formation current is 0.1C.

6. The rapid screening method for low-temperature sodium ion batteries according to claim 1, characterized in that: The temperature of the low temperature condition is lower than 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°C.

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 a carbonate electrolyte.

10. Use of the rapid screening method for low-temperature sodium ion batteries according to any one of claims 1 to 9 in the preparation of sodium ion batteries and electrical equipment.

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