Formation method for a sodium-ion single battery

Abstract

The present invention discloses a formation method for a sodium-ion single battery, which includes constant current charging of the sodium-ion single battery at a charging rate of 0.1C - 0.5C under the condition of 20 - 25°C, and the charging cut-off voltage is V C1 and standing still for 30 - 60 minutes, placing the single battery under the condition of 2 - 10°C for 1 - 2 h, and using voltage V C2 to perform constant voltage charging for 2 - 5 seconds and then standing still for 3 - 8 seconds, standing still for 30 - 60 minutes under the condition of 20 - 25°C, and performing constant current discharging of the sodium-ion single battery at a discharging rate of 0.1C - 0.5C, and the discharging cut-off voltage is V D1、 placing the single battery under the condition of 35 - 55°C for 1 - 2 h, and using voltage V D2 to perform constant voltage discharging for 3 - 6 seconds and standing still for 5 - 8 seconds. The formation method of the sodium-ion single battery significantly changes the performance of the sodium-ion battery, effectively improving the first capacity, charge and discharge efficiency, and cycle life of the sodium-ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium-ion batteries, and specifically to a formation method for a sodium-ion single battery. Background Art

[0002] Sodium-ion batteries have good application prospects in the fields of new energy energy storage and power. They have a fast charging speed, excellent high and low temperature performance, and good safety performance. However, their low energy density and cycle life are the main problems restricting their development. Formation is one of the important links in the production of sodium-ion batteries, which directly determines the structure and performance of the solid electrolyte interface film (SEI) formed on the negative electrode, and further affects the performance of sodium-ion batteries such as the first capacity, charge and discharge efficiency, and cycle life.

[0003] There are certain similarities between sodium-ion batteries and lithium-ion batteries in terms of production process and working principle. Therefore, the current formation methods for sodium-ion batteries mainly refer to those for lithium-ion batteries.

[0004] For example, CN108140880A provides a formation method for a sodium-ion single battery or battery. During the formation charging stage, the single battery is charged to a first voltage at which sodium is irreversibly released from the positive electrode material, and in subsequent charge-discharge cycles, the single battery is charged to a second voltage lower than the first voltage.

[0005] CN113097557A provides a sodium-ion battery and its preparation method, including providing a sodium-ion battery to be formed and subjecting it to gradient formation to obtain a sodium-ion battery. The gradient formation includes multiple charge-discharge steps.

[0006] However, the above methods mainly change the charging stage of battery formation, including current and voltage, etc. Their methods are very similar to those for lithium-ion battery formation, and the change in the performance of sodium-ion batteries is not significant, and it is impossible to effectively improve the first capacity, charge and discharge efficiency, and cycle life of sodium-ion batteries. Summary of the Invention

[0007] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this part, the abstract, and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0008] In view of the above and / or existing problems in the formation of sodium-ion single batteries, the present invention is proposed.

[0009] Therefore, the purpose of the present invention is to provide a formation method for a sodium-ion single battery, which significantly changes the performance of sodium-ion batteries and effectively improves the first capacity, charge and discharge efficiency, and cycle life of sodium-ion batteries.

[0010] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0011] A formation method for a sodium-ion single battery, comprising:

[0012] S1. Normal temperature charging: Under the condition of 20-25°C, the sodium-ion single battery is charged at a constant current with a charging rate of 0.1C-0.5C, and the charging cut-off voltage is V C1 and left standing for 30-60 minutes;

[0013] S2. Low temperature pulse charging: The single battery is placed at 2-10°C for 1-2h, and charged at a constant voltage with voltage V C2 for 2-5 seconds and then left standing for 3-8 seconds, repeating 5-8 times;

[0014] S3. Normal temperature discharging: Left standing for 30-60 minutes under the condition of 20-25°C, and the sodium-ion single battery is discharged at a constant current with a discharging rate of 0.1C-0.5C, and the discharging cut-off voltage is V D1；

[0015] S4. High temperature pulse discharging: The single battery is placed at 35-55°C for 1-2h, and discharged at a constant voltage with voltage V D2 for 3-6 seconds, left standing for 5-8 seconds, repeating 4-8 times;

[0016] S5. Repeat the above steps 2-3 times to complete the formation of the sodium-ion single battery.

[0017] As a preferred scheme of a formation method for a sodium-ion battery according to the present invention, wherein, the charging cut-off voltage V C1 has a range of 3.95-4.35V.

[0018] As a preferred scheme of a formation method for a sodium-ion battery according to the present invention, wherein, the voltage V C2 is 1.2-1.5 times of the voltage V C1 .

[0019] As a preferred scheme of a formation method for a sodium-ion battery according to the present invention, wherein, the discharging cut-off voltage V D1 has a range of 2.5-3.0V.

[0020] As a preferred scheme of a formation method for a sodium-ion battery according to the present invention, wherein, the voltage V D2 is 0.8-0.9 times of the voltage V D1 .

[0021] As a preferred embodiment of the formation method of a sodium-ion battery according to the present invention, the positive electrode material of the sodium-ion single battery is a vanadium-based polyanion positive electrode material containing sodium element, a Prussian white-like positive electrode material or a layered oxide positive electrode material.

[0022] As a preferred embodiment of the formation method of a sodium-ion battery according to the present invention, in the negative electrode material of the sodium-ion single battery, the one(s) participating in the charge and discharge electrochemical reaction is a carbon-based material composed of one or more carbon materials, alloy-based negative electrode materials or other sodium storage negative electrode materials, etc.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: In view of the characteristics of the electrode materials of the sodium-ion battery, the present invention strengthens the structure of the electrode materials of the sodium-ion battery and stabilizes the performance of the SEI film through low-temperature pulsed charging and high-temperature pulsed discharging, which can effectively improve the insertion / extraction ability of sodium ions in the positive and negative electrode materials and stabilize the structure of the electrode materials, thereby significantly improving the first capacity, charge and discharge efficiency and cycle life of the sodium-ion battery. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the drawings and specific embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts. Among them:

[0025] Figure 1 It is a flowchart of a formation method of a sodium-ion battery according to the present invention. Detailed Embodiments

[0026] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the drawings.

[0027] Secondly, the present invention will be described in detail with reference to the schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally out of the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width and depth should be included.

[0028] In order to make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the drawings.

[0029] The present invention provides a formation method for a sodium-ion single battery, which significantly changes the performance of the sodium-ion battery and effectively improves the first capacity, charge and discharge efficiency and cycle life of the sodium-ion battery.

[0030] Figure 1 The figure shows a flowchart of the formation method of the ionic monomer battery of the present invention. The following will describe in detail the specific process of the formation method of this sodium-ion monomer battery in conjunction with Figure 1 Make a detailed description of the specific process of the formation method of this sodium-ion monomer battery.

[0031] Example 1

[0032] Using a vanadium-based polyanion material Na3V2(PO4)3 as the positive electrode and hard carbon as the negative electrode, an unformed sodium-ion battery monomer with a theoretical capacity of 20 Ah is prepared, and the sodium-ion battery monomer is formed using a charge and discharge formation cabinet;

[0033] S1. Normal temperature charging: Under the condition of 25 °C, the sodium-ion monomer battery is charged at a constant current with a charging current of 2.0 A, the charging cut-off voltage is 3.95 V, and it is left standing for 30 minutes.

[0034] S2. Low-temperature pulsed charging: The monomer battery is placed at 10 °C for 2 h, charged at a constant voltage with a voltage of 5.92 V for 2 seconds and then left standing for 3 seconds, and repeated 5 times.

[0035] S3. Normal temperature discharging: The monomer battery is placed at 25 °C and left standing for 30 minutes, and the sodium-ion monomer battery is discharged at a constant current with a discharging current of 2.0 A, and the discharging cut-off voltage is 2.50 V.

[0036] S4. High-temperature pulsed discharging: The monomer battery is placed at 55 °C for 1 h, discharged at a constant voltage with a voltage of 2.00 V for 3 seconds, left standing for 5 seconds, and repeated 4 times.

[0037] S5. Repeat the above steps 2 times.

[0038] Then, under the condition of 25 °C, the sodium-ion monomer battery is charged at a constant current with a charging current of 2 A for 2 h. Through the above process, the formation process of the sodium-ion battery with a theoretical capacity of 20 Ah is completed, and the state of charge (SOC) of sodium ions is 20%.

[0039] Example 2

[0040] Using a Prussian white-like positive electrode material Na2Mn[Mn(CN)6] as the positive electrode and a Na-Sn-Ga ternary alloy as the negative electrode, an unformed sodium-ion battery monomer with a theoretical capacity of 5 Ah is prepared, and the sodium-ion battery monomer is formed using a charge and discharge formation cabinet:

[0041] S1. Normal temperature charging: Under the condition of 20 °C, the sodium-ion monomer battery is charged at a constant current with a charging current of 2.5 A, the charging cut-off voltage is 4.35 V, and it is left standing for 60 minutes.

[0042] S2. Low-temperature pulsed charging: Place the single battery at 2°C for 1 h, perform constant-voltage charging at a voltage of 5.22 V for 5 s and then stand still for 8 s, and repeat 8 times.

[0043] S3. Normal-temperature discharging: Place the single battery at 20°C and let it stand still for 60 min, perform constant-current discharging on the sodium-ion single battery at a discharging current of 2.5 A, and the discharging cut-off voltage is 3.00 V.

[0044] S4. High-temperature pulsed discharging: Place the single battery at 35°C for 2 h, perform constant-voltage discharging at a voltage of 2.70 V for 6 s, stand still for 8 s, and repeat 8 times.

[0045] S5. Repeat the above steps 3 times.

[0046] Then, at 20°C, perform constant-current charging on the sodium-ion single battery at a charging current of 2.5 A for 1 h. Through the above process, complete the formation process of the sodium-ion battery with a theoretical capacity of 5 Ah and make the state of charge (SOC) of sodium ions 50%.

[0047] Example 3

[0048] Using layered oxide cathode material Na 0.4 Co 0.5 Ni 0.2 Cu 0.1 O2 as the cathode and mesophase carbon microspheres as the anode, prepare an unformed sodium-ion battery single cell with a theoretical capacity of 30 Ah, and use a charge-discharge formation cabinet to form the sodium-ion battery single cell:

[0049] S1. Normal-temperature charging: At 22°C, perform constant-current charging on the sodium-ion single battery at a charging current of 6.0 A, the charging cut-off voltage is 4.20 V, and let it stand still for 50 min.

[0050] S2. Low-temperature pulsed charging: Place the single battery at 5°C for 1.5 h, perform constant-voltage charging at a voltage of 5.46 V for 4 s and then stand still for 6 s, and repeat 7 times.

[0051] S3. Normal-temperature discharging: Place the single battery at 22°C and let it stand still for 50 min, perform constant-current discharging on the sodium-ion single battery at a discharging current of 6.0 A, and the discharging cut-off voltage is 2.85 V.

[0052] S4. High-temperature pulsed discharging: Place the single battery at 35°C for 2 h, perform constant-voltage discharging at a voltage of 2.42 V for 5 s, stand still for 6 s, and repeat 7 times.

[0053] S5. Repeat the above steps 2 times.

[0054] Then, at 22 °C, the sodium-ion single battery is charged at a constant current of 6.0 A for 3 h. Through the above process, the formation process of a sodium-ion battery with a theoretical capacity of 30 Ah is completed, and the state of charge (SOC) of sodium ions is 60%.

[0055] In the charging or discharging rate in the above Examples 1 - 3, C is the theoretical design capacity of the sodium-ion single battery, with the unit of mAh or Ah.

[0056] To verify the effects of the above examples, three comparative examples are provided below.

[0057] Comparative Example 1

[0058] The materials are the same as those in Example 1. Using a vanadium-based polyanion material Na3V2(PO4)3 as the positive electrode and hard carbon as the negative electrode, an unformed sodium-ion battery single body with a theoretical capacity of 20 Ah is prepared. The formation method uses a conventional method, that is, without the low-temperature pulse charging and high-temperature pulse discharging processes.

[0059] Comparative Example 2

[0060] The materials are the same as those in Example 2. Using a Prussian white-like positive electrode material Na2Mn[Mn(CN)6] as the positive electrode and a Na-Sn-Ga ternary alloy as the negative electrode, an unformed sodium-ion battery single body with a theoretical capacity of 5 Ah is prepared. The formation method uses a conventional method, that is, without the low-temperature pulse charging and high-temperature pulse discharging processes.

[0061] Comparative Example 3

[0062] The materials are the same as those in Example 3. Using a layered oxide positive electrode material Na 0.4 Co 0.5 Ni 0.2 Cu 0.1 O2 as the positive electrode and mesophase carbon microspheres as the negative electrode, an unformed sodium-ion battery single body with a theoretical capacity of 30 Ah is prepared. The formation method uses a conventional method, that is, without the low-temperature pulse charging and high-temperature pulse discharging processes.

[0063] The various data measured in the above Examples 1 - 3 and Comparative Examples 1 - 3 are summarized in the following table:

[0064]

[0065]

[0066] As can be seen from the above table, the indicators such as the initial capacity, charge-discharge efficiency, and remaining capacity after cycling of Examples 1-3 are all superior to those of the corresponding Comparative Examples 1-3, indicating that for the electrode material characteristics of sodium-ion batteries, the present invention strengthens the structure of the electrode material of sodium-ion batteries and stabilizes the performance of the SEI film through low-temperature pulse charging and high-temperature pulse discharging, which can effectively improve the insertion / extraction ability of sodium ions in the positive and negative electrode materials and stabilize the structure of the electrode material, thereby significantly improving the initial capacity, charge-discharge efficiency, and cycle life of sodium-ion batteries.

[0067] Although the present invention has been described above with reference to the embodiments, various improvements can be made thereto and components thereof can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be combined with each other in any way, and the exhaustive description of these combinations is omitted in this specification only for the consideration of saving space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A formation method for a sodium-ion monomer battery, characterized in that, Including: S1. Normal temperature charging: Under the condition of 20 - 25 °C, the sodium-ion single battery is charged at a constant current with a charging rate of 0.1C - 0.5C, and the charging cut-off voltage is V C1 and it is left standing for 30 - 60 minutes. Among them, the charging cut-off voltage V C1 ranges from 3.95V to 4.35V; S2. Low-temperature pulsed charging: Place the single cell at 2 - 10 °C for 1 - 2 h, and use voltage V C2 to perform constant-voltage charging for 2 - 5 seconds and then rest for 3 - 8 seconds, repeating 5 - 8 times. Among them, the voltage V C2 is 1.2 - 1.5 times of voltage V C1 ; S3. Normal temperature discharge: Leave it standing for 30 - 60 minutes under the condition of 20 - 25 °C, and perform constant current discharge on the sodium ion single cell at a discharge rate of 0.1C - 0.5C until the discharge voltage reaches V D1 , where the cut-off discharge voltage V D1 ranges from 2.5 - 3.0V; S4. High-temperature pulsed discharge: Place the single cell under the condition of 35 - 55 °C for 1 - 2 h, and perform constant-voltage discharge at voltage V D2 for 3 - 6 seconds, then stand still for 5 - 8 seconds, and repeat 4 - 8 times. Among them, the voltage V D2 is 0.8 - 0.9 times of the voltage V D1 ; S5. Repeat the above steps 2 - 3 times to complete the formation of the sodium-ion single battery.

2. The formation method of a sodium-ion single battery according to claim 1, characterized in that, The positive electrode material of the sodium-ion single battery is a vanadium-based polyanion positive electrode material containing sodium element, a Prussian white-like positive electrode material, or a layered oxide positive electrode material.

3. The formation method of a sodium-ion monomer battery according to claim 1, characterized in that, In the negative electrode material of the sodium-ion single battery, the carbon-based material participates in the charge and discharge electrochemical reaction, and the carbon-based material is composed of a carbon material, an alloy-based negative electrode material, or other sodium storage negative electrode materials.

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