Battery formation method, battery and power utilization device

Abstract

The invention discloses a battery formation method, a battery and an electric device, and belongs to the technical field of batteries. According to the method, a battery is soaked and pre-charged in sequence, then pulse charging is performed on the battery during charging, and ultrasonic treatment and continuous air exhaust are performed on the battery while pulse charging is performed. And after charging is finished, carrying out shelving treatment and aging treatment to finish formation. Charging is carried out under the multi-physical field synergistic effect of an ultrasonic wave field formed by ultrasound, a pulse electromagnetic field formed by pulse charging and a negative pressure field formed by air exhaust, the quality of an SEI film can be improved, polarization is reduced, and the cycle performance of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a battery formation method, a battery and a power utilization device. BACKGROUND

[0002] In the preparation of a secondary battery, such as a lithium battery, it is generally necessary to perform formation on the battery after injection of electrolyte, so as to activate the active material of the positive and negative electrodes of the battery and form an SEI film on the surface of the negative electrode. Formation is a very complex process and is also an important process affecting the performance of the battery.

[0003] However, according to the current formation method, the cycle performance of the battery after formation is poor. SUMMARY

[0004] Based on the above-mentioned deficiencies, the present application provides a battery formation method, a battery and a power utilization device to improve the problem of poor cycle performance of the battery after formation in the related art.

[0005] The present application is implemented as follows: In a first aspect, examples of the present application provide a battery formation method, comprising the following steps: An infiltration step: performing infiltration treatment on the battery; A pre-charging step: charging the battery at a first charging rate to a target voltage; A charging step: performing pulse charging on the battery at a second charging rate, and simultaneously performing ultrasonic and continuous air extraction on the battery. The second charging rate is greater than the first charging rate; A standing step: standing the battery for a set time; An aging step: performing aging treatment on the battery.

[0006] In the above implementation process, when performing formation on the battery after injection of electrolyte, the battery is sequentially subjected to infiltration and constant current pre-charging, which can promote the initial penetration of the electrolyte into the macroscopic pores of the electrode and activate the electrode material. Then the battery is simultaneously subjected to ultrasonic, pulse charging and continuous air extraction. The pulse electromagnetic field generated during pulse charging can promote mass transfer and reduce concentration polarization. The ultrasonic field can generate effective micro-jets and shear forces in the electrolyte, forcing the electrolyte to penetrate into the microscopic pores of the electrode. Continuous air extraction can remove the generated gas in real time, avoiding the accumulation of gas bubbles in the pores of the electrode, which disturbs the formation environment of the SEI film and affects the penetration of the electrolyte. Under the synergistic effect of the above-mentioned ultrasonic field, pulse electromagnetic field and negative pressure field formed by air extraction, the infiltration effect of the electrolyte can be improved, the film quality of the SEI film can be improved, and the polarization can be reduced. After charging, the battery is sequentially subjected to standing and aging treatment, the formation of the battery is completed, and the cycle performance of the battery is improved.

[0007] In conjunction with the first aspect, in an optional embodiment of this application, the frequency of the ultrasound is 20kHz to 100kHz. And / or, the power density of the ultrasound is 3W / cm². 2 ~3.5W / cm 2 .

[0008] In the above implementation process, applying an ultrasonic field with appropriate ultrasonic power while pulse charging the battery can generate cavitation in the electrolyte, producing and collapsing microbubbles, forming strong microjets and shear forces. These forces can disrupt the retention layer at the electrode-electrolyte interface, forcing the electrolyte to penetrate into the micropores of the electrode, improving the wettability of the electrolyte, and enhancing the quality of the SEI film. Furthermore, the ultrasonic power density is controlled at 3 W / cm². 2 ~3.5W / cm 2 This ensures that the ultrasonic field uniformly covers the electrode surface, avoiding localized overheating or damage.

[0009] In conjunction with the first aspect, in optional embodiments of this application, the parameters of pulse charging include at least one of the following a~d: a. Pulse duty cycle is 50%~60%; b. The pulse frequency is 1Hz~5Hz; c. The battery is a lithium iron phosphate battery, with a second charging rate of 0.75C~1C; d. The battery is a lithium iron phosphate battery, and the cutoff voltage for pulse charging is 3.2V~3.4V.

[0010] In the above implementation process, during pulse charging of the battery, the pulse duty cycle is controlled at 50%~60%. During the pulse, a thin diffusion layer can be formed on the electrode surface, promoting the rapid diffusion of active ions. The electrolyte can replenish ions to the diffusion layer during the interval, reducing concentration polarization. Controlling the second charging rate of the lithium iron phosphate battery during pulse charging to 0.75C~1C can significantly improve the formation efficiency while ensuring the quality of SEI film formation. Controlling the cutoff voltage of the lithium iron phosphate battery pulse charging to 3.2V~3.4V can achieve a balance between effectively activating battery activity and strictly controlling side reaction gas production, laying the foundation for subsequent aging processes.

[0011] In conjunction with the first aspect, in an optional embodiment of this application, the frequency of the ultrasound is 40kHz to 45kHz, and the pulse frequency is 1Hz to 5Hz. During the charging step, pulse charging and ultrasound are started simultaneously.

[0012] In the above implementation process, pulse charging and ultrasound are simultaneously started while the battery is being charged. The 1Hz pulse frequency is matched with the 40kHz ultrasound cycle, which not only avoids interference but also optimizes the diffusion layer and promotes the conduction of active ions.

[0013] In conjunction with the first aspect, in an optional embodiment of this application, during the charging step, the battery is continuously evacuated to maintain the vacuum level inside the battery at -85kPa to -65kPa.

[0014] In the above process, during the formation of the battery, the battery is continuously evacuated to maintain the vacuum level inside the battery at -85kPa to -65kPa. This effectively removes the gases generated by electrolyte decomposition and side reactions, preventing the accumulation of gases in the electrode pores that could affect the quality of the SEI film formation. At the same time, it also prevents the battery structure from being damaged by excessively high vacuum inside the battery, thereby improving the battery's cycle performance.

[0015] In conjunction with the first aspect, in an optional embodiment of this application, the impregnation step includes a method for impregnation treatment comprising: Immerse the battery in an environment of 40℃~50℃ for more than 10 hours.

[0016] In the above process, before charging the battery, it is immersed in an environment of 40℃~50℃ for more than 10 hours. This can reduce the viscosity of the electrolyte by utilizing the temperature effect, while avoiding electrolyte decomposition, and promote its initial penetration into the macroscopic pores of the electrode. This helps to form a more uniform SEI film during subsequent charging and formation, and further improves the cycle performance of the battery.

[0017] In conjunction with the first aspect, in an optional embodiment of this application, the first charging rate in the pre-charging step is 0.1C to 0.33C.

[0018] In the above implementation process, before the battery undergoes ultrasonic and pulse charging, it is first charged to the target voltage at a constant current with an appropriate small charging rate. This can gently activate the electrode materials, avoid side reactions caused by large current, ensure the stability of the battery, and further improve the cycle performance of the battery.

[0019] In conjunction with the first aspect, in an optional embodiment of this application, during the pre-charging step, the battery is continuously evacuated to maintain the vacuum level inside the battery at -85kPa to -65kPa.

[0020] In the above implementation process, during the pre-charging of the battery, the battery is continuously evacuated to maintain the vacuum level inside the battery at -85kPa to -65kPa. This effectively removes the gases generated by electrolyte decomposition and side reactions, preventing the accumulation of gases in the electrode pores from affecting the quality of SEI film formation. At the same time, it also prevents the battery structure from being damaged by excessively high vacuum inside the battery, thereby improving the battery's cycle performance.

[0021] In conjunction with the first aspect, in optional embodiments of this application, the battery is placed in an environment of 40°C to 50°C for a pre-charging step. And / or, the battery is placed in an environment of 40°C to 50°C for a charging step.

[0022] In the above process, the battery is placed in a high-temperature environment of 40℃~50℃ during pre-charging and ultrasonic and pulse charging. This reduces the viscosity of the electrolyte, accelerates ion diffusion and reaction, and the stable temperature can also avoid uneven reaction caused by thermal fluctuations, ensuring uniform formation of the SEI film.

[0023] In conjunction with the first aspect, in an optional embodiment of this application, the battery is left to rest for 15 to 30 minutes during the resting step.

[0024] And / or, in the aging step, the battery is placed in an environment of 40℃~50℃ for aging treatment for 10h~14h.

[0025] In the above process, after ultrasonic and pulse charging of the battery, the lithium battery is left to rest for 15 to 30 minutes to release internal stress and initially stabilize the SEI film. Then, the battery is aged in a constant temperature environment of 40°C to 50°C for 10 to 14 hours to fully stabilize the SEI film, which helps to improve the long-term cycle performance of the battery.

[0026] In a second aspect, an example of this application provides a battery prepared according to the formation method provided in the first aspect.

[0027] In the above-mentioned implementation process, the formation method provided in the first aspect is used to form the battery, which enables the battery to have good cycle performance.

[0028] In a second aspect, an example of this application provides an electrical device including the battery provided in the second aspect.

[0029] In the above implementation process, the above-mentioned battery is used to power the electrical device. The battery has good cycle performance and can improve the service life of the electrical device. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0031] Figure 1 A chemical formation process flow diagram provided for embodiments of this application; Figure 2 An ultrasonic scan of the lithium battery after formation provided in Example 1; Figure 3 Ultrasonic scan image of the lithium battery after formation, provided for Comparative Example 1; Figure 4 This is a physical image of the negative electrode interface of the lithium battery after full charge disassembly provided in Example 1; Figure 5 A physical image of the negative electrode interface of a fully charged lithium battery disassembled for Comparative Example 1. Figure 6 The graphs show the internal resistance test curves for Example 1 and Comparative Example 1. Detailed Implementation

[0032] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0033] Formation is an important step in the manufacturing process of secondary batteries, including lithium batteries, and directly affects the battery performance after formation, such as cycle performance.

[0034] For example, the relevant technology adopts a process flow of "liquid injection - high-temperature wetting - constant flow formation". However, the above formation process often has the following problems that urgently need to be solved: (1) The micro-wetting effect of the electrolyte is not ideal, and the pores inside the electrode often cannot be fully filled.

[0035] (2) The process is energy-intensive and inefficient, and the high-temperature conditions need to be maintained for a long time, which greatly increases the production cost.

[0036] (3) Severe polarization occurs during constant current formation, which affects the formation quality of SEI film.

[0037] (4) Finally, if the gas production is not controlled thoroughly enough, air bubbles will remain inside the battery, affecting the battery's consistency.

[0038] To improve battery cycle performance, a pulse charging method was attempted for battery formation. Research revealed that while a single pulse charging method could promote the diffusion of active ions to the electrode surface and reduce concentration polarization, the electrolyte exhibited poor wettability on the electrode surface. The electrolyte could not effectively penetrate the micropores of the electrode, resulting in insufficient wetting, which affected film quality and ultimately failed to effectively improve battery cycle performance.

[0039] To further optimize battery cycle performance, an attempt was made to apply an ultrasonic field during pulse charging. The study found that while coupling the ultrasonic field with the pulsed battery could induce cavitation in the electrolyte, generating and collapsing microbubbles to create strong microjets and shear forces, thus disrupting the retention layer at the electrode-electrolyte interface and forcing the electrolyte to penetrate into the electrode micropores, the gases generated by electrolyte decomposition and side reactions inside the battery could not be expelled in time. This led to bubble accumulation, which not only easily destabilized the SEI film formation environment but also affected the electrolyte's penetration into the electrode micropores, ultimately failing to effectively improve battery cycle performance.

[0040] Based on this, an embodiment of this application provides a battery formation method, please refer to [link to relevant documentation]. Figure 1 It includes the following steps: Immersion step: Immerse the battery in water.

[0041] Pre-charging step: Charge the battery at a constant current to the target voltage using the first charging rate.

[0042] Charging procedure: The battery is pulse-charged at a second charging rate, and simultaneously subjected to ultrasonic treatment and continuous evacuation. The second charging rate is greater than the first charging rate.

[0043] Resting procedure: Set a resting time for the battery.

[0044] Aging process: The battery undergoes an aging process.

[0045] During battery formation, the battery is sequentially immersed and pre-charged to promote the initial penetration of the electrolyte into the macroscopic pores of the electrodes and to activate the electrode materials. Then, the battery is simultaneously subjected to ultrasonic and pulse charging, while continuous evacuation is performed. The pulsed electromagnetic field promotes mass transfer and reduces concentration polarization, while the ultrasonic field generates effective microjets and shear forces in the electrolyte, forcing the electrolyte to penetrate into the microscopic pores of the electrodes. Continuous evacuation removes generated gas in real time, preventing the accumulation of bubbles in the electrode pores. The synergistic effect of the multiple physical fields—ultrasonic field, pulsed electromagnetic field, and negative pressure field created by evacuation—improves the electrolyte wetting effect, enhances the SEI film formation quality, reduces polarization, and improves the battery's cycle performance. After charging, the battery undergoes resting and aging treatments to complete its formation.

[0046] It is understood that the aforementioned battery refers to a battery awaiting formation after electrolyte injection. During battery formation, the battery is not sealed to allow for continuous evacuation. As an example, the battery includes a casing and a cell housed inside the casing. The cell includes a positive current collector, a positive electrode plate, a separator, a negative electrode plate, and a negative current collector. Electrolyte is injected through an injection port on the casing. After electrolyte injection is complete, the injection port is not sealed. An external vacuuming device is connected to the injection port to extract the gas inside the battery casing. The vacuuming device includes, but is not limited to, a vacuum pump. To facilitate monitoring the gas pressure inside the casing, the vacuuming device is also equipped with a pressure gauge. To facilitate measuring the volume of extracted gas, a gas meter can also be installed at the pipeline.

[0047] This application does not limit the specific type of battery; the battery can be a conventional lithium battery or sodium battery, etc., as described in this art. As an example, depending on the type of cathode material, the battery is a lithium battery, which can be a lithium transition metal oxide lithium battery or an olivine-structured lithium phosphate lithium battery. For example, the lithium battery can be a lithium iron phosphate battery, a lithium manganese iron phosphate battery, or a ternary lithium battery.

[0048] The aforementioned continuous evacuation of the battery refers to continuously evacuating the battery during the ultrasonic and pulse charging process. In some embodiments, the battery is continuously evacuated while being ultrasonically and pulse charged to maintain the vacuum level inside the lithium battery at -85kPa to -65kPa.

[0049] By continuously evacuating the battery to maintain the internal vacuum at -85kPa to -65kPa, the gas generated by electrolyte decomposition and side reactions can be effectively extracted, preventing the accumulation of gas in the electrode pores from affecting the quality of SEI film formation. At the same time, it can also prevent the battery structure from being damaged by excessively high internal vacuum, thereby improving the battery's cycle performance.

[0050] As an example, while performing ultrasonic and pulse charging on the battery, the vacuum level inside the battery can be maintained within one or more of -65 kPa, -70 kPa, -75 kPa, -80 kPa, or -85 kPa. For instance, while performing ultrasonic and pulse charging on the battery, the vacuum level inside the battery can be maintained at -85 kPa.

[0051] Ultrasonication of a battery refers to generating ultrasonic waves in the electrolyte within the battery. It is understood that when a high-frequency electrical signal acts on a piezoelectric material, the material vibrates rapidly, and this vibration propagates in a medium (such as the electrolyte of this application), thus generating ultrasonic waves.

[0052] In some embodiments, the frequency of the ultrasound is 20 kHz to 100 kHz. Applying an ultrasonic field with a power of 20 kHz to 100 kHz while pulse charging the battery can generate cavitation in the electrolyte, producing and collapsing microbubbles, forming strong microjets and shear forces. These forces can disrupt the retention layer at the electrode-electrolyte interface, forcing the electrolyte to penetrate into the micropores of the electrode, improving the wettability of the electrolyte, and enhancing the quality of the SEI film.

[0053] As an example, the frequency of ultrasound can be one of 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz or 100 kHz or any range between two of them.

[0054] Furthermore, in some embodiments, the frequency of the ultrasound can be 30kHz to 50kHz.

[0055] Furthermore, in some embodiments, the frequency of the ultrasound can be 40kHz to 45kHz.

[0056] For example, the frequency of ultrasound can be 40 kHz.

[0057] In some embodiments, the power density of the ultrasound is 3 W / cm². 2 ~3.5W / cm 2 Power density refers to the power delivered per unit area of ​​the battery's electrodes.

[0058] The power density of the ultrasound was controlled at 3 W / cm². 2 ~3.5W / cm 2 This ensures that the ultrasonic field uniformly covers the electrode surface, avoiding localized overheating or damage.

[0059] As an example, the power density of ultrasound can be 3 W / cm². 2 3.1W / cm 2 3.2W / cm 2 3.3W / cm 2 3.4W / cm 2 Or 3.5W / cm 2 The range between one or both of these. For example, the power density of ultrasound can be 3 W / cm². 2 .

[0060] Pulse charging is a battery charging technology based on periodic changes in current or voltage. In some embodiments, when pulse charging a battery, the pulse duty cycle is 50% to 60%. The pulse duty cycle refers to the ratio of the on-time within a pulse cycle to the total time. When pulse charging a battery, controlling the pulse duty cycle to 50% to 60% allows a thin diffusion layer to form on the electrode surface during the pulse, promoting rapid diffusion of active ions. The electrolyte bulk can replenish ions to the diffusion layer during the intervals, reducing concentration polarization.

[0061] As an example, when the battery is pulse-charged, the pulse duty cycle can be one of 50%, 55%, or 60%, or any range between two of them.

[0062] In some embodiments, when the battery is pulse-charged, the pulse frequency is 1Hz to 5Hz.

[0063] As an example, when pulse charging a battery, the pulse frequency can be one of 1Hz, 2Hz, 3Hz, 4Hz, or 5Hz, or any range between two of them.

[0064] For example, when performing ultrasonic and pulse charging on a battery, the pulse duty cycle can be controlled at 50%, the pulse frequency at 1Hz, and the ultrasonic frequency at 40kHz. Matching the 1Hz pulse frequency with the 40kHz ultrasonic cycle not only avoids interference but also optimizes the diffusion layer and promotes the conduction of active ions. The 50% pulse duty cycle and 1Hz pulse current optimize ion transport.

[0065] In some embodiments, when pulse charging is performed on the lithium iron phosphate battery, the second charging rate is 0.75C to 1C. Controlling the second charging rate to 0.75C to 1C can significantly improve the formation efficiency while ensuring the quality of the SEI film formation.

[0066] As an example, when pulse charging a lithium iron phosphate battery, the second charging rate can be one of 0.75C, 0.85C, or 1C, or any range between two of them. For instance, when pulse charging a lithium iron phosphate battery, the second charging rate can be 1C.

[0067] In some embodiments, when pulse charging is performed on lithium iron phosphate batteries, the cutoff voltage of the pulse charging is 3.2V to 3.4V. As an example, the cutoff voltage is 3.4V. Controlling the cutoff voltage of the pulse charging to 3.4V can achieve a balance between effectively activating battery activity and strictly controlling the gas production of side reactions, laying the foundation for subsequent aging and other processes.

[0068] Furthermore, in some embodiments, the battery is placed in an environment of 40°C to 50°C, and simultaneously subjected to ultrasonic and pulse charging. Exposing the battery to a high-temperature environment of 40°C to 50°C during ultrasonic and pulse charging reduces electrolyte viscosity, accelerates ion diffusion and reaction, and the stable temperature also avoids uneven reaction caused by thermal fluctuations, ensuring uniform SEI film formation. At this time, a multi-physics field can be constructed, comprising ultrasonic, pulsed electromagnetic, negative pressure, and temperature fields. Through the synergistic effect of these multiple physical fields, the battery's cycle performance can be further improved.

[0069] As an example, when the battery is simultaneously subjected to ultrasonic and pulse charging, the battery temperature can be controlled to a range of 40°C, 45°C, or 50°C, or any two of them.

[0070] Furthermore, during the ultrasonic and pulse charging process of the battery, data can be collected in real time at 1-second intervals by integrating voltage, temperature and pressure sensors, and the ultrasonic power, pulse parameters and negative pressure level can be dynamically adjusted based on this data to ensure that the process is always under the above parameter conditions.

[0071] Furthermore, in some embodiments, the wetting step includes a wetting treatment method comprising: Immerse the battery in an environment of 40℃~50℃ for more than 10 hours.

[0072] Before charging the battery, immersing it in an environment of 40℃~50℃ for more than 10 hours can reduce the viscosity of the electrolyte by utilizing the temperature effect, while avoiding electrolyte decomposition, and promote its initial penetration into the macroscopic pores of the electrode. As a pretreatment, this can enhance the macroscopic penetration of the electrolyte and reduce the burden of subsequent formation.

[0073] As an example, during the immersion step, the battery can be placed in a constant temperature environment of 40°C, 45°C, or 50°C for 10h, 11h, 12h, 13h, or 14h.

[0074] High-temperature wetting can improve wetting efficiency, especially for electrodes. For electrode systems with simple pore structures and good wettability, the wetting temperature and wetting time can be adjusted to further improve efficiency, provided that the initial wetting effect is guaranteed.

[0075] Furthermore, in some embodiments, the first charging rate in the pre-charging step is 0.1C to 0.33C. Constant current charging means that the current intensity does not change periodically and remains constant.

[0076] Before ultrasonic and pulse charging of batteries such as lithium batteries, the batteries are first charged to the target voltage at a constant current at a charging rate of 0.1C to 0.33C. This can gently activate the electrode materials, avoid side reactions caused by high current, ensure battery stability, and further improve the battery's cycle performance.

[0077] As an example, in the pre-charging step, the charging rate can be one of 0.1C, 0.2C, or 0.33C, or a range between any two. For example, the charging rate can be 0.1C.

[0078] As an example, the battery is a lithium iron phosphate battery, which is charged at a constant current to 3.2V at a charging rate of 0.1C.

[0079] During the pre-charging process, some reactions occur and gas is generated. In order to extract the gas in a timely manner and reduce the accumulation of this gas, which would affect the film formation quality of the subsequent SEI film and the amount of gas generated during circulation, in some embodiments, the battery is continuously evacuated during the pre-charging step.

[0080] Furthermore, in some embodiments, during the pre-charging step, the battery is continuously evacuated to maintain an internal vacuum of -85 kPa to -65 kPa. Continuously evacuating the battery during pre-charging to maintain an internal vacuum of -85 kPa to -65 kPa effectively removes gases generated by electrolyte decomposition and side reactions, preventing gas accumulation in electrode pores that could affect the SEI film formation quality. It also prevents excessively high internal vacuum from damaging the battery structure, thus improving the battery's cycle performance.

[0081] During the pre-charging step, the vacuum level inside the battery can be maintained within one or more of -65 kPa, -70 kPa, -75 kPa, -80 kPa, or -85 kPa. For example, the vacuum level inside the lithium battery can be maintained at -85 kPa while the battery is being ultrasonically and pulse-charged.

[0082] Furthermore, in some embodiments, the battery is placed in an environment of 40°C to 50°C for a pre-charging step.

[0083] As an example, during the pre-charging step, the battery temperature can be controlled to be one of 40°C, 45°C, or 50°C, or any combination thereof.

[0084] The battery temperature is maintained at 40~50℃ during the immersion step, pre-charging step, ultrasonic and pulse charging steps. The battery temperature is more stable throughout the formation process, which helps to improve the battery's cycle performance.

[0085] In some embodiments, the battery is left to rest for 15 to 30 minutes during the resting step.

[0086] In some embodiments, during the aging process, the battery is placed in an environment of 40°C to 50°C for 10 to 14 hours.

[0087] Furthermore, embodiments of this application provide a formation method for a lithium iron phosphate battery, comprising the following steps performed sequentially: Immersion step: Immerse the lithium iron phosphate battery in an environment of 40℃~50℃ for more than 10 hours.

[0088] Pre-charging steps: Place the lithium iron phosphate battery in an environment of 40℃~50℃, charge the lithium iron phosphate battery at a constant current to 3.2V with a first charging rate of 0.1C, and continuously evacuate the lithium iron phosphate battery to maintain the vacuum degree inside the lithium iron phosphate battery at -85kPa~-65kPa.

[0089] Charging procedure: Place the lithium iron phosphate battery in an environment of 40℃~50℃ and perform pulse charging. Simultaneously, perform ultrasonic treatment and continuous evacuation to maintain the internal vacuum level of the lithium iron phosphate battery at -85kPa~-65kPa. The ultrasonic frequency is 40kHz~45kHz, and the ultrasonic power density is 3W / cm². 2 The pulse duty cycle is 50%~60%, the pulse frequency is 1Hz~5Hz, the second charging rate is 0.75C~1C, and the pulse charging to cutoff voltage is 3.4V.

[0090] Resting procedure: Let the lithium iron phosphate battery rest for 15 to 30 minutes.

[0091] Aging treatment: Place the lithium iron phosphate batteries in an environment of 40℃~50℃ for 10h~14h.

[0092] This application also provides a battery, prepared by the above-described formation method. The battery provided by this application has good cycle performance. Based on the active ion composition, the battery of this application can be a lithium battery or a sodium battery. As an example, the battery is a lithium battery. Based on the positive electrode material of the lithium battery, the lithium battery of this application can be a lithium transition metal oxide lithium battery or an olivine-structured lithium phosphate lithium battery. For example, lithium iron phosphate batteries, lithium manganese iron phosphate batteries, or ternary lithium batteries.

[0093] Furthermore, this application also provides an electrical device including the aforementioned battery.

[0094] The aforementioned battery can be used as a power source for an electrical device or as an energy storage unit for an electrical device. Electrical devices may include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0095] The battery formation method of this application will be further described in detail below with reference to the embodiments.

[0096] Example 1 This embodiment provides a battery formation method, including: (1) Providing a lithium battery to be formed: Assemble the positive electrode current collector (aluminum foil), positive electrode sheet (lithium iron phosphate type, calculated by mass percentage, including 97% lithium iron phosphate, 1.9% PVDF, 0.7% conductive carbon, 0.3% carbon nanotubes and 0.1% dispersant), separator (polyethylene separator), and negative electrode sheet (graphite negative electrode type, calculated by mass percentage, including 96.05% graphite, 3.1% SBR@CMC binder and 0.85% conductive carbon) into a cell and install it into the casing. Inject the electrolyte into the casing through the injection hole. The electrolyte is LiPF6 (the solvent includes a mixture of ethylene carbonate, diethyl carbonate and dimethyl carbonate).

[0097] (2) Immersion step: Immerse the above lithium battery in an environment of 45°C for 12 hours.

[0098] (3) Pre-charging step: Place the lithium battery in an environment of 45°C, charge the lithium battery at a constant current to 3.2V with a first charging rate of 0.1C, and continuously pump air from the lithium battery to maintain the vacuum degree inside the lithium battery at -85kPa.

[0099] (4) Charging steps: Place the lithium battery in an environment of 45°C, and simultaneously turn on the ultrasonic and pulse power supply and the vacuum pump to perform ultrasonic and pulse charging on the lithium battery at the same time, while continuously evacuating the lithium battery to maintain the vacuum degree inside the lithium battery at -85kPa. The ultrasonic frequency is 40kHz, and the ultrasonic power density is 3W / cm². 2 The pulse duty cycle is 50%, the pulse frequency is 1Hz, the second charging rate is 1C, and the pulse charging to the cutoff voltage is 3.4V.

[0100] (5) Resting step: Let the lithium battery rest for 15 minutes.

[0101] (6) Aging step: Place the lithium battery in an environment of 45°C for 12 hours for aging treatment.

[0102] A gas meter is installed in the gas extraction equipment to count the amount of gas produced throughout the entire formation process.

[0103] Example 2 This embodiment provides a battery formation method, which differs from Embodiment 1 in that: in step (4), the second charging rate is 0.75C.

[0104] Example 3 This embodiment provides a battery formation method, which differs from Embodiment 1 in that: in step (4), the pulse duty cycle is 60%.

[0105] Example 4 This embodiment provides a battery formation method, which differs from Embodiment 1 in that: in step (4), the pulse frequency is 5Hz.

[0106] Comparative Example 1 This comparative example provides a battery formation method, which differs from Example 1 in that: in step (4), the lithium battery is placed in an environment of 45°C and charged to 3.4V at a constant current rate of 0.5C. Ultrasonic treatment is not performed, and the lithium battery is continuously evacuated to maintain the vacuum degree inside the lithium battery at -85kPa.

[0107] Comparative Example 2 This comparative example provides a battery formation method, which differs from Example 1 in that: in step (4), the lithium battery is placed in an environment of 45°C and charged at a constant current of 1C to 3.4V without ultrasonication, and the lithium battery is continuously evacuated to maintain the vacuum degree inside the lithium battery at -85kPa.

[0108] Comparative Example 3 This comparative example provides a battery formation method, which differs from Example 1 in that: in step (4), the lithium battery is placed in an environment of 45°C, pulse charging is performed on the lithium battery without ultrasonication, and the lithium battery is continuously evacuated to maintain the vacuum degree inside the lithium battery at -85kPa. The pulse duty cycle is 50%, the pulse frequency is 1Hz, the second charging rate is 1C, and the pulse charging to the cutoff voltage is 3.4V.

[0109] Comparative Example 4 This comparative example provides a battery formation method, which differs from Example 1 in that: in step (4), the lithium battery is placed in an environment of 45°C, and the lithium battery is subjected to ultrasonic and constant current charging at a charging rate of 0.5C, and the lithium battery is continuously evacuated to maintain the vacuum degree inside the lithium battery at -85kPa.

[0110] Comparative Example 5 This comparative example provides a battery formation method, which differs from Example 1 in that: in steps (2) and (4), the lithium battery is not continuously evacuated, and the inside of the lithium battery is at atmospheric pressure.

[0111] The process parameters for the above embodiments and comparative examples are shown in Table 1.

[0112] Table 1

[0113] Test case (1) Immersion effect test The formed lithium batteries provided in Example 1 and Comparative Example 1 were subjected to ultrasonic scanning. The ultrasonic scan image of Example 1 is shown below. Figure 2 For the ultrasound scan of Comparative Example 1, see [link to Comparative Example 1]. Figure 3 .

[0114] Results Analysis: In ultrasound scanning, red indicates high ultrasound transmittance (outside the battery), a color closer to green indicates moderate ultrasound transmittance (normal wetting), and a color closer to blue indicates low ultrasound transmittance (gas or poor wetting). Comparison Figure 2 and Figure 3 It can be seen that, Figure 3 The ultrasound scanning interface formed by constant fluidization contains a large area of ​​poorly infiltrated blue region (circled by the black curve in the image), while Figure 2 The ultrasound scanning interface formed by ultrasound-pulse-negative pressure coupling shows a relatively small blue area.

[0115] (2) The fully charged lithium batteries (fully charged at a constant current of 0.33C) formed in Example 1 and Comparative Example 1 were disassembled, and the electrode interfaces were observed. For a physical image of the disassembled electrode in Example 1, please refer to [link to image]. Figure 4 For a comparison of the electrode disassembly diagram in Example 1, please refer to the actual disassembled image. Figure 5 .

[0116] Results analysis: Figure 5 The presence of purple spots at the negative electrode interface indicates defects during formation, resulting in poor SEI film quality. Figure 4 The negative electrode interface in the film has a good morphology after disassembly, indicating that the formation method provided in the embodiments of this application can improve the film quality and reduce defects.

[0117] (3) Battery internal resistance The formed lithium batteries provided in Example 1 and Comparative Example 1 were subjected to HPPC battery internal resistance testing. Test parameters included: charging at 0.75C at 25°C, and 1C current pulse discharge for 30 seconds at different states of charge (SOC). The internal resistance test curves for Example 1 and Comparative Example 1 are shown below. Figure 6 .

[0118] Results analysis: From Figure 6 As can be seen, the lithium battery provided in Embodiment 1 of this application has a lower internal resistance than that of Comparative Example 1 when not in a charged state. This indicates that the formation method provided in this embodiment can eliminate the polarization voltage accumulated inside the battery and promote uniform ion distribution, thereby significantly reducing the internal resistance of the battery.

[0119] (4) Cyclic performance test The formed lithium batteries provided in the above embodiments and comparative examples were subjected to cycle performance tests. The test method included: charging to 3.4V at a constant current rate of 0.33C in a constant temperature environment of 25°C, letting it stand for 5 minutes, and then discharging to 2.5V at a rate of 1C, recording the discharge capacity. The preceding process was repeated to obtain the capacity retention rate after 1400 cycles. The capacity retention rate = discharge capacity at the specified number of cycles / discharge capacity in the first cycle × 100%. A higher capacity retention rate indicates better cycle performance of the lithium battery. The test results are shown in Table 2.

[0120] Table 2

[0121] In Table 2, the formation time is the charging time in step (4), excluding the soaking and pre-charging time in the early stage.

[0122] Results Analysis: Table 2 shows that the lithium batteries provided in Examples 1-4 maintained a capacity retention rate of no less than 91.8% after 1400 cycles, which is higher than that of Comparative Examples 1-4. This indicates that the formation method provided in this application, which simultaneously performs ultrasonic and pulse charging and continuous evacuation during formation, can improve the cycle performance of the lithium batteries after formation. Figures 2-6 The testing patterns are consistent.

[0123] Example 2: Reducing the second charge rate to 0.75C slows the reaction rate, significantly prolongs the formation time, results in a milder reaction, minimizes gas production, and achieves the best cycle life, but at the cost of efficiency. Example 3: Increasing the pulse duty cycle to 60% increases the effective charging time and minimizes the formation time, but insufficient relaxation exacerbates side reactions, significantly increases gas production, and slightly reduces cycle life. Example 4: Increasing the pulse frequency to 5Hz weakens the relaxation effect and reduces its synergistic effect with the ultrasonic frequency, resulting in slightly worse gas production and cycle performance compared to Example 1.

[0124] Furthermore, comparing Example 1 and Comparative Example 1, it can be seen that the formation time of Example 1 is shortened to 102 minutes compared to 155 minutes in Comparative Example 1, which can effectively reduce energy consumption and production costs during formation. The gas production of Example 1 is reduced to 50 mL compared to 88 mL in Comparative Example 1, indicating that the formation method provided in this application provides more uniform electrolyte wetting, which can improve concentration polarization and weaken the overall process side reactions, thus resulting in lower gas production. Comparative Example 1, without special physical field assistance, has low efficiency, high gas production, and poor cycle life.

[0125] Compared with Comparative Example 1 and Comparative Example 2, Comparative Example 2 only increased the constant current charging rate. Although the formation time was the shortest, the side reactions were severe, the gas production was the largest, and the cycle life deteriorated sharply.

[0126] In Comparative Example 3, without ultrasonic field assistance, electrolyte wetting and reaction uniformity deteriorated, leading to prolonged formation time, increased gas production, and decreased cycle life. In Comparative Example 4, 0.5C constant current charging was used. Although ultrasound and negative pressure improved reaction efficiency, the lack of pulse suppression for side reactions resulted in significantly worse gas production and cycle life compared to Example 1. In Comparative Example 5, without negative pressure, the reaction gas could not escape, leading to fatal defects such as purple spots and lithium plating inside the battery, causing battery failure.

[0127] In summary, the formation method provided in this application embodiment, during the charging step, simultaneously performs ultrasonic and pulse charging on the battery and continuously evacuates the battery. Under the synergistic effect of multiple physical fields such as ultrasonic field, pulse electric field, negative pressure field and temperature field, the wettability of electrolyte can be improved, the film formation quality of SEI film can be improved, concentration polarization can be improved, the internal resistance of battery can be reduced, and thus the cycle performance of battery can be improved.

[0128] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for forming a battery, characterized in that, Includes the following steps: Immersion step: Immerse the battery in water; Pre-charging step: Charge the battery to the target voltage at a constant current using a first charging rate; Charging steps: The battery is pulse-charged at a second charging rate, and the battery is subjected to ultrasonic treatment and continuous evacuation during the pulse charging process. The second charging rate is greater than the first charging rate; Setting aside steps: Set aside the battery for a set time; Aging step: The battery is subjected to aging treatment.

2. The formation method according to claim 1, characterized in that, The frequency of the ultrasound is 20kHz to 100kHz; and / or, the power density of the ultrasound is 3W / cm². 2 ~3.5W / cm 2 .

3. The formation method according to claim 2, characterized in that, The parameters of the pulse charging include at least one of the following a~d: a. Pulse duty cycle is 50%~60%; b. The pulse frequency is 1Hz~5Hz; c. The battery is a lithium iron phosphate battery, and the second charging rate is 0.75C~1C; d. The battery is a lithium iron phosphate battery, and the pulse charging to the cutoff voltage is 3.2V~3.4V.

4. The formation method according to claim 3, characterized in that, The frequency of the ultrasound is 40kHz~45kHz, and the frequency of the pulse is 1Hz~5Hz; in the charging step, the pulse charging and the ultrasound are started simultaneously.

5. The formation method according to any one of claims 1 to 4, characterized in that, During the charging process, the battery is continuously evacuated to maintain a vacuum level of -85kPa to -65kPa inside the battery.

6. The formation method according to claim 1, characterized in that, The impregnation step includes the following methods: The battery is immersed in an environment of 40℃~50℃ for more than 10 hours.

7. The formation method according to claim 1 or 3, characterized in that, In the pre-charging step, the first charging rate is 0.1C to 0.33C.

8. The formation method according to claim 7, characterized in that, In the pre-charging step, the battery is continuously evacuated to maintain the vacuum level inside the battery at -85kPa to -65kPa.

9. The formation method according to claim 1, characterized in that, The battery is placed in an environment of 40℃~50℃ for the pre-charging step; And / or, the battery is placed in an environment of 40°C to 50°C for the charging step.

10. The formation method according to claim 1, characterized in that, In the resting step, the battery is rested for 15 to 30 minutes; And / or, in the aging step, the battery is placed in an environment of 40℃~50℃ for aging treatment for 10h~14h.

11. A battery, characterized in that, Prepared by the formation method according to any one of claims 1 to 10.

12. An electrical appliance, characterized in that, Includes the battery as described in claim 11.

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