Lithium battery formation method and structure thereof

Abstract

The invention discloses a formation method and structure of a lithium battery, and the method comprises the following steps: step A, baking the assembled and welded battery, then injecting liquid, and putting the battery on a formation cabinet after high-temperature infiltration; step B, forming charging steps are set, and stepped current segmented charging is adopted; c, starting a formation process; by installing the precise gas pressure sensor in the battery cover plate, the internal pressure value of the battery is monitored in real time, the formation system is fed back in time, and the opening and closing value of the negative pressure pipeline valve is adjusted in real time, so that the internal pressure of the battery is always in a stable and controllable state, and the internal environment of the battery is in dynamic balance in the formation process; the method is beneficial to improvement of battery formation performance, reduction of formation liquid loss, optimization of formation steps and guidance of batch production of products.

Description

Technical Field

[0001] The present invention specifically relates to a lithium battery formation method and its structure. Background Art

[0002] During the formation process of the battery, the voltage continuously rises, and the additives in the electrolyte will undergo chemical reactions, participate in the formation of the SEI film and generate different gases. The gases accumulate between the separator and the electrode plate, which will cause problems such as black spot lithium deposition at the electrode plate interface, resulting in poor battery performance.

[0003] In the prior art, soft-pack batteries will retain an air bag during the production process for collecting the gas generated during formation, and degassing and cutting are carried out in the final sealing process; square batteries will undergo negative-pressure formation, and the gases generated during the formation process will be discharged through a negative-pressure pipeline. The large cylindrical battery is similar to the square battery, and neither can realize the real-time collection of the internal pressure of the battery. For engineers, it is impossible to dynamically set the negative-pressure process steps during the formation process. Therefore, we propose a lithium battery formation method and its structure. Summary of the Invention

[0004] The purpose of the present invention is to provide a lithium battery formation method and its structure to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A lithium battery formation method includes the following steps:

[0006] Step A: Bake the battery after assembly and welding, then inject liquid, and put the battery on the formation cabinet after high-temperature infiltration;

[0007] Step B: Set the formation charging process steps and charge in a stepped current in segments;

[0008] Step C: Start the formation process. After the pressure sensor component senses the gas pressure, start the air extraction of the formation cabinet;

[0009] Step D: As the gas increases, the pressure sensor component feeds back to the negative-pressure air extraction system, and the air path valve gradually opens wider;

[0010] Step E: The pressure sensor component timely opens and closes the negative-pressure air extraction system of the formation cabinet according to the internal air pressure of the battery to make the internal air pressure of the battery consistent;

[0011] Step G: After the formation process is completed, the battery is removed from the formation cabinet and flows into the next process.

[0012] By monitoring the air pressure change inside the battery cell in real time and feedback-adjusting the opening and closing value of the negative pressure air extraction system valve in real time, the inside of the battery cell is always maintained in a stable state. The negative pressure formation process helps the active substances inside the battery to be more evenly distributed, avoiding bubble or uneven gas evolution phenomena, which is beneficial to the improvement of the battery formation performance and is conducive to providing data for later research.

[0013] Preferably, in step A, the baking temperature is 80 - 110 °C, the battery after baking is filled with liquid in an environment of -60 KPa to -95 KPa, the high temperature is 40 - 50 °C, and after soaking for 24 - 48 h, the battery is put on the formation cabinet.

[0014] It is convenient to accurately control the temperature, pressure and soaking time, which can ensure the internal and external uniformity and stability of the battery, and improve the performance, life and safety of the battery.

[0015] Preferably, in step B, a stepped current segmented design is adopted: in the first stage, a current of 0.01C - 0.05C is used for constant current charging to 2.0 - 2.8V, and the charging time is 60 - 180 min; in the second stage, a current of 0.05C - 0.15C is used for constant current charging to 2.8 - 3.2V, and the charging time is 60 - 180 min; in the third stage, a current of 0.15C - 0.3C is used for constant current charging to 3.2 - 3.65V, and the charging time is 60 - 180 min; a 10 - minute rest time is set between each stage.

[0016] Through stepped segmented charging, starting with low - current slow charging and then gradually increasing the current, both the charging speed and the battery health are taken into account. During the charging process, the battery can obtain an appropriate charging strategy, so as to maximize the charging efficiency without sacrificing the battery life.

[0017] Preferably, in step E, after the pressure sensor component senses the gas pressure, it feeds back to the negative pressure air extraction system of the formation cabinet. At this time, the opening value of the degassing pipeline valve is 0 - 10%.

[0018] By combining the pressure sensor, real - time feedback control and fine - tuning the valve opening, the pressure control accuracy during the formation process can be effectively improved, and the consistency and stability of the battery can be enhanced.

[0019] Preferably, in step F, when the battery voltage reaches 2.5 - 2.8V, the instantaneous gas production reaches the peak value, and the pressure sensor component feeds back to the negative pressure air extraction system. At this time, the gas path valve is opened to the relative maximum value of 50% - 70% to ensure that the internal air pressure of the battery is always maintained stable.

[0020] By combining a control system that monitors the battery voltage and gas emissions in real time, the opening degree of the gas path valve is precisely adjusted, effectively ensuring the stability of the internal pressure of the battery. At the same time, it also enhances the automation and intelligence level of the production process and reduces the intervention of manual operation.

[0021] Preferably, in step C, organic substances, inorganic substances, and gases are generated by the reaction of electrolyte additives during the formation process.

[0022] A formation layer structure of a lithium battery includes:

[0023] A cover plate, with pole columns respectively arranged at both ends inside the cover plate;

[0024] A housing, arranged on the lower surface of the cover plate, and an opening matching the cover plate is provided on the housing;

[0025] A liquid injection hole, opened inside the cover plate and communicating with the inside of the housing;

[0026] A pressure sensor assembly, arranged in the middle inside the cover plate to monitor the pressure inside the housing.

[0027] It is convenient to detect the pressure inside the battery housing in a timely manner when injecting electrolyte, so as to perform reasonable exhaust during formation.

[0028] Preferably, there are two pole columns to form the positive and negative electrodes, an insulating pad is arranged on the outer surface of the pole column, and an explosion-proof valve is arranged inside the cover plate.

[0029] Preferably, the pressure sensor assembly includes a sensor, a welding piece, and a collection wire. The welding piece is arranged inside a through hole opened in the middle inside the cover plate, a sensor is fixed on the lower surface of the welding piece, and a collection wire electrically connected to the sensor is arranged on the welding piece.

[0030] It is convenient to better collect the pressure value inside the battery housing in real time and transmit information to the outside.

[0031] Preferably, fixing claws matching the cover plate are arranged at the four corners of the lower surface of the welding piece.

[0032] It is convenient to firmly connect the welding piece to the housing.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] By installing a precision gas pressure sensor inside the battery cover plate, the present invention monitors the internal air pressure value of the battery in real time, feeds back to the formation system in a timely manner, and adjusts the opening and closing value of the negative pressure pipeline valve in real time, ensuring that the internal pressure of the battery is always in a stable and controllable state, ensuring that the internal environment of the battery is in dynamic balance during the formation process, which is beneficial to improving the formation performance of the battery, reducing the liquid loss during formation, helping to optimize the formation process steps, and guiding the mass production of products. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic flow chart of the present invention;

[0036] Figure 2 is a schematic structural diagram of the present invention;

[0037] Figure 3 is a schematic structural diagram of the housing of the present invention;

[0038] Figure 4 is a schematic structural diagram of the pressure sensor assembly of the present invention.

[0039] In the figure: 10, cover plate; 11, pole; 13, insulating pad; 14, liquid injection hole; 15, explosion-proof valve; 16, pressure sensor assembly; 161, sensor; 162, welding piece; 163, acquisition line; 164, fixing claw; 21, housing; 22, opening. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] Embodiment 1

[0042] Please refer to Figures 1 - 4 , the present invention provides a technical solution: a formation method for a lithium battery, including the following steps:

[0043] Step A: Bake the battery after assembly and welding, then inject liquid, and put the battery on the formation cabinet after high-temperature infiltration;

[0044] Step B: Set the formation charging process steps and charge in a stepped current segment;

[0045] Step C: Start the formation process. After the pressure sensor assembly 16 senses the gas pressure, start the air extraction of the formation cabinet;

[0046] Step D: As the gas increases, the pressure sensor assembly 16 feeds back to the negative pressure air extraction system, and the air path valve gradually opens wider;

[0047] Step E: The pressure sensor assembly 16 feeds back to the negative pressure pumping system of the formation cabinet to open and close in a timely manner according to the internal air pressure of the battery, so that the internal air pressure of the battery is consistent.

[0048] Step F: After the formation process is completed, the battery is unloaded from the formation cabinet and flows into the next process.

[0049] By real-time monitoring of the air pressure change inside the battery cell and real-time feedback to adjust the opening and closing value of the negative pressure pumping system valve, it is ensured that the inside of the battery cell always maintains a stable state. The negative pressure formation process helps the active material distribution inside the battery to be more uniform, avoids bubble or uneven gas evolution phenomena, reduces the structural damage caused by gas expansion inside the battery. When the battery is formed in a negative pressure environment, it can effectively reduce the internal stress formed during the charge and discharge process, avoid the rupture and damage of the internal material structure of the battery, thereby improving the battery life and stability, being beneficial to the improvement of the battery formation performance, and also being conducive to providing data for later research.

[0050] Preferably, in step A, the temperature during baking is 80 - 110°C, the battery after baking is injected with liquid in an environment of -60 KPa to -95 KPa, the high temperature is 40 - 50°C, and after soaking for 24 - 48 h, the battery is placed on the formation cabinet.

[0051] The temperature range of 80 - 110°C in step A: This temperature condition usually helps to promote the dehydration of materials, bubble removal or the volatilization of other substances, ensuring that the active materials and electrolytes inside the battery can work evenly and stably in subsequent steps.

[0052] The high temperature of 40 - 50°C during liquid injection: This temperature range is moderate, which helps the penetration and uniform distribution of the battery electrolyte, enabling the internal structure of the battery to be better soaked, and improving the battery performance and life.

[0053] Through the precise control of temperature, pressure and soaking time, it is possible to ensure the internal and external uniformity and stability of the battery, and improve the battery performance, life and safety.

[0054] Preferably, in step B, a stepped current segmented design is adopted: in the first stage, a current of 0.01C - 0.05C is used for constant current charging to 2.0 - 2.8V, and the charging time is 60 - 180 min; in the second stage, a current of 0.05C - 0.15C is used for constant current charging to 2.8 - 3.2V, and the charging time is 60 - 180 min; in the third stage, a current of 0.15C - 0.3C is used for constant current charging to 3.2 - 3.65V, and the charging time is 60 - 180 min; a 10 - minute standing time is set between each stage.

[0055] By gradually increasing the current, it is possible to avoid excessive current during charging, which may cause the battery to heat up or overcharge. The current at each stage is set according to the charging state of the battery, which helps to ensure that the battery can be charged in the best state at each stage and prevent problems such as overcharging and overheating of the battery.

[0056] Battery temperature control: At each charging stage, by limiting the current, it is possible to effectively avoid excessive battery temperature, which is crucial for extending the battery life. Furthermore, through stepped segmented charging, starting with low-current slow charging and then gradually increasing the current, both the charging speed and battery health are taken into account. During the charging process, the battery can obtain an appropriate charging strategy, thereby maximizing the charging efficiency without sacrificing the battery life.

[0057] Preferably, in step E, after the pressure sensor assembly 16 senses the gas pressure, it feeds back to the negative pressure extraction system of the formation cabinet. At this time, the opening value of the degassing pipeline valve is 0 - 10%.

[0058] By combining the pressure sensor, real-time feedback control, and fine adjustment of the valve opening, the pressure control accuracy during the formation process can be effectively improved, and the consistency and stability of the battery can be enhanced.

[0059] Preferably, in step F, when the battery voltage reaches 2.5 - 2.8V, the instantaneous gas production reaches the peak value. The pressure sensor assembly 16 feeds back to the negative pressure extraction system, and at this time, the gas path valve is opened to a relatively maximum value of 50% - 70% to ensure that the internal pressure of the battery is always maintained stable.

[0060] By combining a control system that monitors the battery voltage and gas emission in real time, precisely adjusting the opening of the gas path valve can effectively ensure the stability of the internal pressure of the battery, avoid excessive gas accumulation or pressure fluctuations, contribute to improving the cycle stability of the battery, reduce internal material damage caused by unstable pressure, thereby extending the battery life, and at the same time enhancing the automation and intelligent level of the production process and reducing the intervention of manual operation.

[0061] Preferably, in step C, during the formation process, the electrolyte additive reacts to generate organic substances, inorganic substances, and gases.

[0062] A formation layer structure of a lithium battery, comprising:

[0063] A cover plate 10, with pole columns 11 respectively arranged at both ends inside the cover plate 10;

[0064] A housing 21, arranged on the lower surface of the cover plate 10, and an opening 22 matching the cover plate 10 is provided on the housing 21;

[0065] A liquid injection hole 14, opened inside the cover plate 10 and communicating with the inside of the housing 21;

[0066] A pressure sensor assembly 16 is disposed in the middle of the inner side of the cover plate 10 to monitor the pressure inside the housing 21.

[0067] By disposing the pressure sensor assembly 16 on the cover plate 10, it is convenient to be able to well perform real-time detection on the pressure inside the housing 21, so as to facilitate reasonable exhaust during formation.

[0068] Preferably, two pole posts 11 are provided to form the positive and negative electrodes, and an insulating pad 13 is provided on the outer surface of the pole post 11, and an explosion-proof valve 15 is provided inside the cover plate 10.

[0069] Preferably, the pressure sensor assembly 16 includes a sensor 161, a welding piece 162 and a collection wire 163. The welding piece 162 is disposed inside a through hole opened in the middle of the inner side of the cover plate 10, and the sensor 161 is fixed on the lower surface of the welding piece 162, and a collection wire 163 electrically connected to the sensor 161 is provided on the welding piece 162.

[0070] It is convenient to better perform real-time collection on the pressure value inside the housing 21 of the battery, transmit information to the outside, the device structure is simple, the installation is convenient, and the practical effect of the device is increased.

[0071] Preferably, fixing claws 164 are provided at the four corners of the lower surface of the welding piece 162 for fitting and fixing with the cover plate 10.

[0072] It is convenient to improve the convenience of installation and fixation, and at the same time, the connection firmness between the welding piece 162 and the housing 21 is good.

[0073] Embodiment 2

[0074] This embodiment provides a formation method for a lithium battery, including the following steps:

[0075] A: The battery after assembly and welding is baked in an oven at a temperature of 95°C. The baked battery core is subjected to a first liquid injection in an environment of -85 KPa, infiltrated at a high temperature of 45°C for 28 h, and then the battery is put on a formation cabinet.

[0076] B: Set the formation charging process steps, and adopt a stepped current segmented design: in the first stage, a current of 0.03C is adopted, and constant current charging is carried out until 2.8V, the charging time is 120 min, and the standing time is 10 min; in the second stage, a current of 0.1C is adopted, and constant current charging is carried out until 3.2V, the charging time is 180 min, and the standing time is 10 min; in the third stage, a current of 0.2C is adopted, and constant current charging is carried out until 3.65V, the charging time is 120 min, and the standing time is 10 min, and then stop.

[0077] C: During the first-stage charging process of the battery, the initial internal pressure of the battery is 0 KPa. At this time, the opening and closing value of the gas path valve is 0%. Starting from 2.2 V, gas gradually generates inside the battery, and the internal pressure of the battery increases. The pressure sensor senses the pressure value and feeds it back to the formation system, and the opening and closing value of the gas path valve increases to 10%.

[0078] D: As the reaction proceeds, the battery voltage gradually increases. When it reaches 2.8 V, the instantaneous gas generation rate can reach nearly 0.2 mL / s. During the process from 2.2 V to 2.8 V, the instantaneous gas generation rate continuously increases, and the opening and closing value of the gas path valve slowly increases from 10% to 60%. The negative pressure inside the battery slowly changes from 0 KPa to -80 KPa within 5 minutes, ensuring the minimum liquid loss. When the first-stage cut-off condition is reached, the charging stops, and the opening and closing value of the gas path valve drops to 30%. The negative pressure inside the battery changes from -80 KPa to -10 KPa.

[0079] E: When the second-stage charging is carried out after the static state ends, the voltage gradually increases from 2.8 V to 3.2 V, the instantaneous gas generation rate gradually decreases from 0.2 mL / s, the opening and closing value of the gas path valve slowly increases from 30% to 50%, and the negative pressure inside the battery slowly changes from -10 KPa to -60 KPa within 5 minutes. When the second-stage cut-off condition is reached, the charging stops, the opening and closing value of the gas path valve drops to 30%, and the negative pressure inside the battery changes from -60 KPa to -10 KPa.

[0080] F: When the third-stage charging is carried out after the static state ends, the voltage gradually increases from 3.2 V to 3.65 V, the instantaneous gas generation rate is basically 0, the opening and closing value of the gas path valve remains unchanged at 30%, the negative pressure inside the battery remains at -10 KPa. When the third-stage cut-off condition is reached, the charging stops, the opening and closing value of the gas path valve drops to 0%, and the negative pressure inside the battery changes from -10 KPa to 0 KPa.

[0081] G: After the formation process is completed, the battery is removed from the formation cabinet and enters the next process.

[0082] Example 3

[0083] This example provides a formation method for a lithium-ion battery with a pressure sensor installed on the cover plate, including the following steps:

[0084] A: The assembled and welded battery is baked in an oven at a temperature of 95 °C. The baked battery core is subjected to a first liquid injection in an environment of -85 KPa, infiltrated at a high temperature of 45 °C for 28 h, and then the battery is placed on the formation cabinet.

[0085] B: Set the formation charging process steps, and adopt a stepped current segmented design: In the first stage, use a current of 0.03C to charge at a constant current until 2.8V, with a charging time of 120 minutes and a standing time of 10 minutes; in the second stage, use a current of 0.1C to charge at a constant current until 3.2V, with a charging time of 180 minutes and a standing time of 10 minutes; in the third stage, use a current of 0.2C to charge at a constant current until 3.65V, with a charging time of 120 minutes and a standing time of 10 minutes, and then stop.

[0086] C: During the first-stage charging process of the battery, the opening and closing value of the gas path valve is 10%. At this time, the initial internal pressure of the battery is -10KPa. Starting from 2.2V, gas is gradually generated inside the battery, and the internal pressure of the battery increases. The pressure sensor senses the pressure value and feeds it back to the formation system, and the opening and closing value of the gas path valve increases to 15%.

[0087] D: As the reaction proceeds, the battery voltage gradually increases. When it reaches 2.8V, the instantaneous gas production rate can reach nearly 0.2 mL / s. During the process from 2.2V to 2.8V, the instantaneous gas production rate continuously increases, and the opening and closing value of the gas path valve slowly increases from 15% to 60%. The internal negative pressure of the battery slowly changes from 0KPa to -85KPa within 5 minutes to ensure the minimum liquid loss. When the first-stage cut-off condition is reached, the charging stops, and the opening and closing value of the gas path valve drops to 20%. The internal negative pressure of the battery changes from -85KPa to -10KPa.

[0088] E: When starting the second-stage charging after the standing period, the voltage gradually increases from 2.8V to 3.2V, the instantaneous gas production rate gradually decreases from 0.2 mL / s, the opening and closing value of the gas path valve slowly increases from 20% to 40%, and the internal negative pressure of the battery slowly changes from -10KPa to -50KPa within 5 minutes. When the second-stage cut-off condition is reached, the charging stops, and the opening and closing value of the gas path valve drops to 20%. The internal negative pressure of the battery changes from -50KPa to -10KPa.

[0089] F: When starting the third-stage charging after the standing period, the voltage gradually increases from 3.2V to 3.65V, the instantaneous gas production rate is basically 0, the opening and closing value of the gas path valve remains unchanged at 20%, and the internal negative pressure of the battery remains at -10KPa. When the third-stage cut-off condition is reached, the charging stops, and the opening and closing value of the gas path valve drops to 0%. The internal negative pressure of the battery changes from -10KPa to 0KPa.

[0090] G: After the formation process is completed, remove the battery from the formation cabinet and enter the next process.

[0091] Comparative Example 1

[0092] Take the batteries produced in the same batch as the examples and adopt the same liquid injection and infiltration process: bake in an oven at a temperature of 95 °C. After baking, perform the first liquid injection on the battery cells in an environment of -85 KPa. After infiltrating at a high temperature of 45 °C for 28 h, put the batteries on the formation cabinet;

[0093] Set the formation charging steps and adopt a stepped current segmented design: In the first stage, use a current of 0.03C for constant current charging to 2.8V, with a charging time of 120 min and a standing time of 10 min; in the second stage, use a current of 0.1C for constant current charging to 3.2V, with a charging time of 180 min and a standing time of 10 min; in the third stage, use a current of 0.2C for constant current charging to 3.65V, with a charging time of 120 min and a standing time of 10 min, and then stop;

[0094] At the beginning of the formation, pump air through the air valve for negative pressure extraction. The valve opening and closing value is 50%, and the negative pressure inside the battery is -80 KPa. During the entire formation process, maintain the valve opening and closing value and the negative pressure value inside the battery unchanged until the end of the entire charging process.

[0095] Table 1

[0096]

[0097] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A formation method for a lithium battery, characterized in that, It includes the following steps: Step A: Bake the assembled and welded battery, then inject liquid, and place the battery on the formation cabinet after high-temperature infiltration; Step B: Set the formation charging process steps and use stepped current for segmented charging; Step C: Start the formation process. After the pressure sensor assembly (16) senses the gas pressure, start the air extraction of the formation cabinet; Step D: As the gas increases, the pressure sensor assembly (16) feeds back to the negative pressure air extraction system, and the gas path valve gradually opens wider; Step E: The pressure sensor assembly (16) feeds back to the negative pressure air extraction system of the formation cabinet in a timely manner according to the internal air pressure of the battery, and opens and closes in a timely manner to make the internal air pressure of the battery consistent; Step F: After the formation process is completed, the battery is unloaded from the formation cabinet and flows into the next process.

2. The formation method of a lithium battery according to claim 1, wherein: In the above-mentioned Step A, the baking temperature is 80 - 110 °C. The battery after baking is injected with liquid in an environment of -60 KPa to -95 KPa. The high-temperature is 40 - 50 °C, and the battery is placed on the formation cabinet after infiltration for 24 - 48 h.

3. A formation method for a lithium battery according to claim 1, characterized in that: In the above-mentioned Step B, a stepped current segmented design is adopted: in the first stage, a current of 0.01C - 0.05C is used for constant current charging to 2.0 - 2.8V, and the charging time is 60 - 180 min; in the second stage, a current of 0.05C - 0.15C is used for constant current charging to 2.8 - 3.2V, and the charging time is 60 - 180 min; in the third stage, a current of 0.15C - 0.3C is used for constant current charging to 3.2 - 3.65V, and the charging time is 60 - 180 min; a 10-minute standing time is set between each stage.

4. A formation method of a lithium battery according to claim 1, characterized in that: In the above-mentioned Step E, after the pressure sensor assembly (16) senses the gas pressure, it feeds back to the negative pressure air extraction system of the formation cabinet. At this time, the opening value of the degassing pipeline valve is 0 - 10%.

5. A formation method of a lithium battery according to claim 1, characterized in that: In the above-mentioned Step F, when the battery voltage reaches 2.5 - 2.8V, the instantaneous gas production reaches the peak value. The pressure sensor assembly (16) feeds back to the negative pressure air extraction system. At this time, the gas path valve opens to the relative maximum value of 50% - 70% to ensure that the internal air pressure of the battery is always maintained stable.

6. A formation method for a lithium battery according to claim 1, characterized in that: In the above-mentioned Step C, organic substances, inorganic substances and gases are generated by the reaction of electrolyte additives in the formation process.

7. A chemical layer structure of a lithium battery, characterized in that, It includes: A cover plate (10), and two pole columns (11) are respectively arranged at both ends inside the cover plate (10); A housing (21), which is arranged on the lower surface of the cover plate (10), and an opening (22) matching the cover plate (10) is provided on the housing (21); A liquid injection hole (14), which is opened inside the cover plate (10) and is communicated with the inside of the housing (21); A pressure sensor assembly (16), which is arranged in the middle inside the cover plate (10) to monitor the pressure inside the housing (21).

8. A passivation layer structure of a lithium battery according to claim 7, characterized in that: Two of the pole columns (11) are provided to form the positive and negative electrodes, and an insulating pad (13) is arranged on the outer surface of the pole column (11), and an explosion-proof valve (15) is arranged inside the cover plate (10).

9. A chemical layer structure of a lithium battery according to claim 7, characterized in that: The pressure sensor assembly (16) includes a sensor (161), a welding piece (162), and a collection wire (163). The welding piece (162) is disposed inside a through hole formed in the middle of the inner side of the cover plate (10), and a sensor (161) is fixed to the lower surface of the welding piece (162). A collection wire (163) electrically connected to the sensor (161) is disposed on the welding piece (162).

10. A passivation layer structure of a lithium battery according to claim 9, characterized in that: Fixing claws (164) that cooperate with the cover plate (10) for fixing are disposed at four corners of the lower surface of the welding piece (162).

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