Sodium-ion battery activation method based on multi-stage gradient formation and application of sodium-ion battery activation method

Abstract

The invention discloses a multi-stage gradient formation sodium ion battery activation method and application thereof, and the method comprises the following steps: S1, pre-passivation treatment: in a standing stage after liquid injection, applying constant-temperature oscillation to a battery to promote an electrolyte to uniformly permeate into electrode pores to form an initial passivation layer; s2, multi-stage gradient charging and discharging: (1) an activation period: under negative pressure, charging to 2.0-4.5 V at a constant current of 0.5 C, then discharging to 0.01 V at a constant current of 0.2 C, breaking a surface passivation layer, and activating an ion channel; (2) an SEI film construction period: charging to 2.5 V by adopting pulse current, then discharging to 0.5 V at a constant current of 0.1 C, and promoting ordered deposition of sodium ions by utilizing an intermittent period of the pulse; and (3) a stable period: under negative pressure, charging to 15-40% SOC with 0.05 C ultra-low current, repairing SEI film defects, and completing formation. According to the invention, the sodium ion battery can have higher capacity retention ratio and more excellent battery cycle performance.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery manufacturing, and in particular to a multi-stage gradient sodium ion battery activation method and application thereof. Background Art

[0002] Sodium-ion batteries (SIBs) are a key alternative to lithium-ion batteries due to their abundant resources and low cost. The formation process is a critical step in battery manufacturing. The initial charge and discharge process forms a stable solid electrolyte interface (SEI) film on the electrode surface, and its quality directly impacts the battery's Coulombic efficiency, cycle life, and safety.

[0003] In the prior art, conventional formation methods usually use constant low current charging and discharging (e.g., 0.1C), which has the following problems:

[0004] 1. Uneven SEI film: A single current results in a fixed sodium ion migration rate, and the SEI film is prone to local over-thickness or rupture;

[0005] 2. Long time and high energy consumption: Low current leads to a formation time of 10-20 hours, resulting in low production efficiency;

[0006] 3. High temperature sensitivity: Side reactions are intensified at high temperatures, and ion diffusion is hindered at low temperatures. Traditional methods cannot adapt to temperature changes.

[0007] Therefore, there is an urgent need for a sodium-ion battery formation method that is efficient, low-energy-consuming, and can dynamically adapt to different environmental conditions. Summary of the Invention

[0008] The object of the present invention is to provide a multi-stage gradient sodium ion battery activation method and its application to solve the above-mentioned defects caused by the prior art.

[0009] A multi-stage gradient sodium ion battery activation method includes the following steps:

[0010] Step 1: Pre-passivation treatment:

[0011] During the resting stage after the injection, the battery is subjected to constant temperature oscillation to promote the electrolyte to evenly penetrate into the electrode pores and form an initial passivation layer;

[0012] Step 2: Multi-stage gradient charge and discharge:

[0013] Stage 1: Activation period: Under a negative pressure of -60 to 85 kPa, charge at a constant current of 0.5 C to 2.0 to 4.5 V, then discharge at a constant current of 0.2 C to 0.01 V to break the passivation layer on the surface of the electrode material and activate the ion channel;

[0014] Phase 2: SEI film construction: Use pulse current to charge to 2.5V, then discharge to 0.5V at a constant current of 0.1C, and use the intermittent period of the pulse to promote the orderly deposition of sodium ions;

[0015] Stage 3: Stabilization period: Under a negative pressure of -60 to 85 kPa, charge to 15 to 40% SOC at an ultra-low current of 0.05C to repair SEI film defects and complete the formation.

[0016] Preferably, during the static stage after liquid injection, the constant temperature is controlled at 25-50° C. and the oscillation frequency is 5-10 Hz.

[0017] Preferably, in stage one, the temperature is controlled at 30-45°C.

[0018] Preferably, in the second stage, the peak value of the pulse current is 0.3C, and the duty cycle is 30% to 50%.

[0019] Preferably, in stage 2, the temperature is controlled at 25±2°C.

[0020] Preferably, in stage three, the temperature is controlled at 20-30°C.

[0021] Compared to existing technologies, this invention proposes a formation method that combines multi-stage gradient charge and discharge with coordinated temperature-current regulation. By adjusting current, voltage, and temperature in stages, this method achieves layer-by-layer densification of the SEI film. Simultaneously, it introduces in-situ electrolyte pre-passivation technology to reduce irreversible capacity loss. This also increases the production capacity of industrialized sodium-ion batteries. Furthermore, this new formation method results in more uniform SEI formation on the electrode surface, resulting in superior battery cycling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Graph showing the capacity retention results for Example 1 and the comparative example. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0024] Example 1

[0025] (1) Place the battery after one injection in a constant temperature oscillator, set the temperature to 40°C and the frequency to 6 Hz for 6 hours to achieve sufficient and uniform infiltration of the battery electrode and the electrolyte, and form an initial passivation layer on the surface of the battery negative electrode.

[0026] (2) The battery after step (1) was cooled to 30°C and charged to 4.0V at a constant current of 0.5C under a negative pressure of -80KPa, and then discharged to 0.01V at a constant current of 0.2C.

[0027] (3) The battery was cooled to 25°C and charged to 2.5V using a pulse current (peak value 0.3C, duty cycle 30%), and then discharged to 0.5V using a constant current of 0.1C. The intermittent period of the pulse was used to promote the orderly deposition of sodium ions.

[0028] (4) The battery was cooled to 20°C and charged to 20% SOC at an ultra-low current of 0.05C under a negative pressure of -60KPa to stabilize and repair the SEI film and complete the formation process.

[0029] Comparative Example

[0030] (1) Place the sodium ion solution after injection in a high-temperature negative pressure formation device at 45±2℃ and let it stand for 48 hours to complete battery impregnation.

[0031] (2) The battery environment was placed at a temperature of 45°C and a negative pressure of -80 kPa, and the battery was charged at a constant current of 0.1 C for 60 minutes to complete the initial activation of the battery.

[0032] (3) The battery environment is placed at a temperature of 45°C and a negative pressure of -80KPa, and the battery is charged to 4.3V at a constant current of 0.2C to complete the entire formation process.

[0033] Figure 1 The graph shows the capacity retention results for Example 1 and the comparative example. The multi-stage gradient sodium ion battery activation method proposed by the present invention achieved a capacity retention rate of 98.54% at the 300th cycle, slightly better than the 98.27% of the conventional sodium ion formation method of the comparative example. At the 1000th cycle, the capacity retention rate of the present invention was 96.11%, while the capacity retention rate of the comparative example was 94.25%. This performance advantage of the present invention becomes more pronounced as the cycles continue. Therefore, the sodium ion battery using the present invention has superior battery cycle performance and extends the life of the sodium ion battery.

[0034] In addition, compared with the traditional sodium ion formation process, the present invention can complete the formation process in a shorter time, improve the production capacity of industrial production of sodium ion batteries, and has good practical application prospects and value.

[0035] Therefore, the embodiments disclosed above are only illustrative in all aspects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A multi-stage gradient sodium ion battery activation method, characterized in that: The following processes are included: Step 1: Pre-passivation treatment: During the resting stage after the injection, the battery is subjected to constant temperature oscillation to promote the electrolyte to evenly penetrate into the electrode pores and form an initial passivation layer; Step 2: Multi-stage gradient charge and discharge: Stage 1: Activation period: Under a negative pressure of -60 to 85 kPa, charge at a constant current of 0.5 C to 2.0 to 4.5 V, then discharge at a constant current of 0.2 C to 0.01 V to break the passivation layer on the surface of the electrode material and activate the ion channel; Phase 2: SEI film construction: Use pulse current to charge to 2.5V, then discharge to 0.5V at a constant current of 0.1C, and use the intermittent period of the pulse to promote the orderly deposition of sodium ions; Stage 3: Stabilization period: Under a negative pressure of -60 to 85 kPa, charge to 15 to 40% SOC at an ultra-low current of 0.05C to repair SEI film defects and complete the formation.

2. A multi-stage gradient sodium ion battery activation method according to claim 1, characterized in that, During the static stage after liquid injection, the constant temperature is controlled at 25-50°C and the oscillation frequency is 5-10Hz.

3. A multi-stage gradient sodium ion battery activation method according to claim 1, characterized in that, In stage one, the temperature is controlled at 30-45°C.

4. A multi-stage gradient sodium ion battery activation method according to claim 1, characterized in that, In the second stage, the peak value of the pulse current is 0.3C, and the duty cycle is 30% to 50%.

5. A multi-stage gradient sodium ion battery activation method according to claim 1, characterized in that, In stage 2, the temperature was controlled at 25±2°C.

6. A multi-stage gradient sodium ion battery activation method according to claim 1, characterized in that, In stage three, the temperature is controlled at 20-30°C.

7. A multi-stage gradient sodium ion battery activation method according to any one of claims 1 to 6, characterized in that: The method is used to optimize the initial charge and discharge process of a sodium ion battery and improve its cycle life and capacity retention rate.

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