Battery impregnation method, secondary battery, and electric device

Abstract

This application provides a battery wetting method, a secondary battery, and an electrical device. The battery wetting method utilizes an exponentially decaying pulse voltage to create an electric field between the positive and negative electrode plates, converting electrical energy into internal energy of the electrolyte. This replenishes the energy dissipated by the electrolyte as it dynamically moves within the electrode plates, helping the electrolyte overcome the interfacial energy with the electrode plates and allowing it to spread rapidly on the plates, thus accelerating wetting and enabling the battery to quickly complete wetting after electrolyte injection, overcoming the bottleneck of difficult wetting of thick electrode plates. Simultaneously, the energy of the exponentially decaying pulse voltage naturally decays, effectively preventing overcharging and lithium plating on the electrode plates. Therefore, this method effectively balances high wetting rate and high capacity / high voltage characteristics of the battery.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, and in particular to a battery impregnation method, a secondary battery, and an electrical device. Background Technology

[0002] Electrode wetting refers to the process by which the electrolyte spreads on the surface of the electrode. The effectiveness of electrode wetting is directly related to the performance of the battery. Poor electrode wetting may lead to a lack of internal electrolyte, which in turn can cause problems with the negative electrode.

[0003] In the prior art, the wettability of the electrode is improved by increasing the thermal motion energy of electrolyte molecules and changing the contact angle between the electrolyte and the electrode. However, the above methods have many limitations and cannot effectively balance the wettability rate with the high capacity and high voltage characteristics of the battery. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a battery impregnation method, a secondary battery, and an electrical device to solve the problem that existing electrode impregnation methods cannot effectively balance the impregnation rate and the high capacity and high voltage characteristics of the battery.

[0005] To solve the above problems, this application provides the following technical solution:

[0006] This application proposes a battery wetting method, comprising:

[0007] Electrolyte is injected into a battery that includes a positive electrode and a negative electrode.

[0008] After the electrolyte injection is completed, the battery is subjected to exponential decay pulse voltage charging.

[0009] Monitor the DCR of the battery, and stop the exponential decay pulse voltage charging process on the battery when the DCR is less than a preset resistance threshold.

[0010] Furthermore, in the battery immersion method, the amplitude of the exponentially decaying pulse voltage satisfies: P(t) = P0(i)·e -t / τ ;

[0011] Where P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is the i-th initial amplitude of the pulse voltage, in V, i takes the values ​​1, 2, 3; e is the base of the natural logarithm; t is time, in s; and τ is the decay time constant of the pulse voltage, in s.

[0012] Furthermore, in the battery immersion method, the second initial amplitude is 3-48V.

[0013] Furthermore, in the battery immersion method, the step of performing exponentially decaying pulse voltage charging on the battery includes:

[0014] The battery is charged using a first exponentially decaying pulse voltage until the DCR of the battery is 50% of its initial DCR.

[0015] After the first exponentially decaying pulse voltage finishes charging, the second exponentially decaying pulse voltage is used for charging until the battery's DCR is 25% of its initial DCR.

[0016] After the second exponentially decaying pulse voltage finishes charging, a third exponentially decaying pulse voltage is used for charging until the battery's DCR is less than the preset resistance threshold.

[0017] Furthermore, the first initial amplitude of the first exponentially decaying pulse voltage is less than the second initial amplitude of the second exponentially decaying pulse voltage, and the second initial amplitude is less than the third initial amplitude of the third exponentially decaying pulse voltage.

[0018] Furthermore, the capacity of the battery is 20-1000 Ah, and the first initial amplitude satisfies the following relationship with the battery capacity:

[0019] z = (-3*10) -5 *x 2 +0.0723*x+4.3499)*3;

[0020] Where x is the capacity of the battery, in Ah; and z is the first initial amplitude, in V.

[0021] Furthermore, in the battery immersion method, the first initial amplitude is 4-6V; the second initial amplitude is 10-15V; and the third initial amplitude is 25-37.5V.

[0022] Furthermore, the preset resistance threshold and the battery capacity satisfy: y = -5 * 10 -8 *x 3 +4*10 -5 *x 2 -0.014*x+2.6895;

[0023] Where y is the preset resistance threshold, in mΩ.

[0024] Furthermore, in the battery immersion method, the ambient temperature is 25–70°C during the exponential decay pulse voltage charging process of the battery.

[0025] Furthermore, in the battery immersion method, the preset resistance threshold is 0.2 to 5 mΩ.

[0026] This application also proposes a secondary battery, which is obtained by the above method.

[0027] This application also proposes an electrical device including the aforementioned secondary battery, wherein the secondary battery serves as the power supply for the electrical device.

[0028] Compared with the prior art, the embodiments of this application have the following advantages:

[0029] In this embodiment, the battery wetting method utilizes an exponentially decaying pulse voltage to create an electric field between the positive and negative electrode plates, converting electrical energy into electrolyte internal energy. This replenishes the energy dissipated by the electrolyte as it dynamically moves within the electrode plates, helping the electrolyte overcome the interfacial energy with the electrode plates and allowing it to spread rapidly on the plates. This accelerates wetting and enables the battery to quickly complete wetting after electrolyte injection, overcoming the bottleneck of difficult wetting of thick electrode plates. Simultaneously, the energy of the exponentially decaying pulse voltage naturally decays, effectively preventing overcharging and lithium plating on the electrode plates. Therefore, this method effectively balances the high wetting rate and high capacity / high voltage characteristics of the battery.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0031] Figure 1 This is a schematic flowchart of the battery immersion method provided in the embodiments of this application.

[0032] Figure 2 This is a schematic diagram of the exponentially decaying pulse voltage charging of the battery immersion method provided in the embodiments of this application. Detailed Implementation

[0033] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, this application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] The applicant of this application discovered that the electrode wetting effect is directly related to the battery performance. Poor electrode wetting can lead to a lack of internal electrolyte, which in turn causes negative electrode problems. In order to improve the energy density of battery cells, existing technologies often use large-size structures and high-capacity, high-voltage materials. However, the above designs can easily affect the electrode wetting effect, leading to a lack of internal electrolyte and thus causing serious negative electrode problems.

[0035] Although the wettability of the electrode can be improved by increasing the thermal motion energy of electrolyte molecules and changing the contact angle between the electrolyte and the electrode, these methods have many limitations and cannot effectively balance the wettability rate with the efficiency of the battery's high capacity and high voltage characteristics.

[0036] To address the aforementioned problems, this application provides a battery wetting method, such as... Figure 1 As shown, steps 101 to 103 are included:

[0037] Step 101: Inject electrolyte into the battery, which includes the positive electrode and the negative electrode.

[0038] In step 101 above, the battery can be a prismatic battery, a cylindrical battery, a pouch battery, or an irregularly shaped battery.

[0039] In step 101 above, the battery can be a wound battery or a stacked battery.

[0040] In step 101 above, the battery may be a sealed or unsealed battery.

[0041] In step 101 above, the battery can be a lithium-ion battery or a sodium-ion battery. The above method is applicable to various electrodes. The positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material, which includes one or more of lithium iron phosphate material, ternary material, lithium manganese oxide material, and lithium cobalt oxide material.

[0042] In step 101 above, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer is selected from non-metallic negative electrode materials. The non-metallic negative electrode material is preferably any one or a combination of at least two of hard carbon, soft carbon, graphite, and silicon suboxide, or graphite material, silicon carbide material, etc.

[0043] In practical applications, the negative electrode, separator and positive electrode are stacked in sequence and wound to obtain a core. The core is then packaged to obtain a bare battery. After baking the bare battery, step 101 above can be performed, which is to perform the electrolyte injection operation.

[0044] Step 102: After the electrolyte injection is completed, the battery is subjected to exponential decay pulse voltage charging.

[0045] In step 102 above, after the electrolyte injection is completed, the positive and negative electrodes of the pulse current generator are connected to the positive and negative electrodes respectively. Then, an exponentially decaying pulse voltage is continuously applied to the battery for charging. The exponentially decaying pulse voltage can create an electric field inside the battery. Lithium ions in the battery electrolyte move in the electric field and gain kinetic energy. This kinetic energy can not only replenish the energy dissipation caused by viscosity dissipation and friction dissipation during the wetting of the electrode at the solid / liquid interface, but also directly promote the spread of the electrolyte on the electrode, which greatly increases the electrode wetting rate and accelerates the wetting of the electrode by lithium ions, thereby shortening the wetting time. At the same time, because the energy of the exponentially decaying pulse voltage will naturally decay, the energy to push the lithium ions in the electrolyte to overcome the interfacial energy between the electrolyte and the electrode gradually decreases, so it can effectively avoid the overcharging and lithium deposition of the electrode.

[0046] Step 103: Monitor the DCR of the battery, and stop the exponential decay pulse voltage charging process on the battery when the DCR is less than the preset resistance threshold.

[0047] In step 103 above, since the DCR of the battery is directly related to its immersion state, it can be determined whether the immersion is complete by monitoring the DCR of the battery. When it is determined that the immersion is complete, the exponential decay pulse voltage charging process on the battery is stopped, which means the battery immersion process is completed.

[0048] In step 103 above, the preset resistance threshold is used to characterize the completion of battery wetting. That is, the preset resistance threshold is the DC internal resistance value when the battery is fully wetting. Therefore, when the DCR of the battery is less than the preset resistance threshold, it can be determined that the electrolyte has fully wetted the electrode, and thus the exponential decay pulse voltage charging process for the battery is stopped.

[0049] Optionally, in one specific embodiment, the preset resistance threshold is 0.2 to 5 mΩ, for example, it can be one or any two of the following values: 0.2 mΩ, 0.3 mΩ, 0.5 mΩ, 0.8 mΩ, 1.0 mΩ, 1.5 mΩ, 2.0 mΩ, 3.0 mΩ, 4.0 mΩ, and 5.0 mΩ.

[0050] Alternatively, in another specific embodiment, the aforementioned preset resistance threshold and battery capacity satisfy: y = -5 * 10 -8 *x 3 +4*10 -5 *x 2 -0.014*x+2.6895;

[0051] Where y is the preset resistance threshold in mΩ; x is the battery capacity, and the value of x ranges from 20 to 1000 Ah.

[0052] In this specific embodiment, the resistance threshold at which the battery is fully wetted is determined in advance based on the actual capacity of the battery. This allows for a more accurate determination of the wettability during subsequent electrolyte wetting. Consequently, when it is determined that the electrolyte has fully wetted the electrode, the exponential decay pulse voltage charging process for the battery is stopped in a timely manner.

[0053] The method provided in this application embodiment not only continuously forms an electric field between the positive and negative electrode plates by using an exponentially decaying pulse voltage, thereby converting electrical energy into electrolyte internal energy under the action of the electric field force, replenishing the energy dissipated by the electrolyte as it dynamically moves within the electrode plate, and helping the electrolyte overcome the interfacial energy between itself and the electrode plate, allowing the electrolyte to spread rapidly on the electrode plate and achieve the purpose of accelerating wetting, thus enabling the battery to quickly complete wetting after electrolyte injection and breaking through the bottleneck of difficult wetting of thick electrode plates; at the same time, the energy of the exponentially decaying pulse voltage naturally decays, which can effectively avoid overcharging and lithium plating of the electrode plate.

[0054] The battery wetting method provided in this application embodiment can significantly improve the electrode wetting rate and reduce the aging waiting time after electrolyte injection, thereby reducing time costs. Therefore, the wetting method provided in this application embodiment solves the problem that existing electrode wetting methods cannot effectively balance the wetting rate and the high capacity and high voltage characteristics of the battery.

[0055] Alternatively, in one embodiment, the amplitude of the exponentially decaying pulse voltage satisfies: P(t) = P0(i)·e -t / τ ;

[0056] Where P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is the i-th initial amplitude of the pulse voltage, in V, i takes the values ​​1, 2, 3; e is the base of the natural logarithm; t is time, in s; and τ is the decay time constant of the pulse voltage, in s.

[0057] In this implementation, the amplitude P(t) is assumed to satisfy P(t) = P0(i)·e -t / τ The exponentially decaying pulse voltage is used to charge the battery, which not only matches the actual energy demand of the battery but also effectively avoids lithium plating caused by overcharging of the electrode.

[0058] The decay time constant τ is determined by the product of the pulse capacitance and resistance, reflecting the decay of the pulse voltage from its initial amplitude to e. -1 V requires a certain amount of time.

[0059] Alternatively, in one implementation, the time constant τ satisfies 10 -3 ≤τ≤1, for example, it can be 0.1.

[0060] Optionally, in one embodiment, the initial amplitude is 3 to 48V, that is, the initial amplitude of the exponentially decaying pulse voltage is within the range of 3 to 48V throughout the entire pulse charging process. For example, it can be one or any two of the following ranges: 3V, 4V, 5V, 8V, 10V, 15V, 20V, 25V, 30V, 40V, and 48V.

[0061] Optionally, in one embodiment, the step of performing exponential decay pulse voltage charging on the battery includes steps 201 to 203:

[0062] Step 201: Charge the battery using a first exponentially decaying pulse voltage until the DCR of the battery is 50% of its initial DCR.

[0063] Step 202: After the first exponentially decaying pulse voltage finishes charging, the second exponentially decaying pulse voltage is used for charging until the battery's DCR is 25% of its initial DCR.

[0064] Step 203: After the second exponentially decaying pulse voltage finishes charging, a third exponentially decaying pulse voltage is used for charging until the DCR of the battery is less than the preset resistance threshold.

[0065] In some embodiments, the first initial amplitude of the first exponentially decaying pulse voltage is less than the second initial amplitude of the second exponentially decaying pulse voltage, and the initial amplitude is less than the third initial amplitude of the third exponentially decaying pulse voltage.

[0066] In step 201, the initial DCR is the DCR of the battery after electrolyte injection and aging test. Before the battery's DCR drops to 50% of its initial DCR, the interfacial resistance between the electrolyte and the electrode is relatively small, and the energy dissipated by the electrolyte moving dynamically within the electrode is relatively small. Therefore, a first exponentially decaying pulse voltage with a relatively small initial amplitude is used for charging.

[0067] In step 202, after the DCR of the battery drops to 50% of its initial DCR, the interfacial resistance between the electrolyte and the electrode will increase significantly, which will also significantly increase the energy dissipated by the electrolyte moving dynamically within the electrode. Therefore, in order to maintain the wetting rate, the energy required to be replenished will also increase rapidly. Thus, a second exponentially decaying pulse voltage with a large initial amplitude is used for charging.

[0068] In step 203, after the DCR of the battery decreases to 25% of its initial DCR, the interfacial resistance between the electrolyte and the electrode will further increase, which will further increase the energy dissipated by the electrolyte moving dynamically within the electrode. Therefore, more energy is required to maintain the wetting rate, so a third exponentially decaying pulse voltage with a larger initial amplitude is used for charging.

[0069] In this embodiment, considering that the interfacial resistance between the electrolyte and the electrode gradually increases with wetting, the energy dissipated by the electrolyte moving dynamically within the electrode also gradually increases. In order to maintain the wetting rate, the energy required to replenish it also gradually increases. Therefore, an exponentially decaying pulse voltage with an initial amplitude increasing is set to charge the battery sequentially, which can alleviate the problem of the wetting rate gradually decreasing due to the gradual increase in interfacial resistance.

[0070] Optionally, in one embodiment, the ratio of the second initial amplitude to the first initial amplitude is a, and the ratio of the third initial amplitude to the second initial amplitude is b; wherein, 1 <a≤10,1<b≤10。

[0071] In this specific embodiment, considering that the interfacial resistance between the electrolyte and the electrode gradually increases with wetting, the energy dissipated by the electrolyte moving dynamically within the electrode also gradually increases. Therefore, the energy required to maintain the wetting rate also gradually increases. Thus, during two adjacent charging processes, the initial amplitude of the exponentially decaying pulse voltage is increased by a multiple of 1 to 10. This effectively replenishes the gradually increasing energy dissipation during the dynamic movement of the electrolyte within the electrode, offsetting the problem of the gradually increasing interfacial resistance between the electrolyte and the electrode, which leads to a gradual decrease in the wetting rate due to the continuous increase in the wetting range. This effectively promotes the dynamic movement of the electrolyte within the electrode and accelerates the overall wetting rate.

[0072] Optionally, in one specific embodiment, the first initial amplitude is 4 to 6V, the second initial amplitude is 10 to 15V, and the third initial amplitude is 25 to 37.5V.

[0073] In this specific embodiment, the first initial amplitude is set to 4-6V, the second initial amplitude is set to 10-15V, and the third initial amplitude is set to 25-37.5V.

[0074] Alternatively, in another specific embodiment, when the battery capacity is 20-1000 Ah, the aforementioned first initial amplitude satisfies the following with respect to the battery capacity:

[0075] z = (-3*10) -5 *x 2 +0.0723*x+4.3499)*3;

[0076] Where x is the battery capacity in Ah; z is the first initial amplitude in V.

[0077] In this specific embodiment, the first initial amplitude of the first exponentially decaying pulse voltage for charging the battery is set in advance according to the battery's design capacity. Then, the second initial amplitude of the second exponentially decaying pulse voltage and the third initial amplitude of the third exponentially decaying pulse voltage can be determined, so that the initial amplitude of each exponentially decaying pulse voltage matches the battery capacity. This can help the electrolyte overcome the interfacial energy between itself and the electrode more quickly and effectively, allowing the electrolyte to spread rapidly on the electrode.

[0078] Optionally, in one embodiment, during the exponential decay pulse voltage charging process of the battery, the ambient temperature is 25–70°C. This effectively improves the wetting rate and ensures the wetting effect while avoiding damage to the battery from high temperatures. Optionally, the aforementioned ambient temperature can be a range of one or any two of 25°C, 27°C, 30°C, 35°C, 40°C, 45°C, 50°C, 60°C, and 70°C.

[0079] Optionally, in one embodiment, the negative electrode sheet includes a negative current collector and a negative active material layer disposed on the negative current collector, wherein the negative active material layer includes a negative active material.

[0080] Optionally, in one specific embodiment, the above-mentioned negative electrode active material can be silicon carbide negative electrode material, graphite, or hard carbon, etc.

[0081] Optionally, in one specific embodiment, the negative electrode sheet further includes a conductive agent and a binder; optionally, the conductive agent includes one or more of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, and graphene, and the binder includes carboxymethyl cellulose-based binders and resin-based binders.

[0082] Optionally, in one embodiment, the carboxymethyl cellulose-based adhesive includes one or more of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose; and / or the resin-based adhesive includes one or more of styrene-butadiene rubber, polyacrylic acid, and polyacrylonitrile.

[0083] In some embodiments, the negative electrode sheet is prepared as follows: the components used to prepare the negative electrode sheet, such as the negative electrode active material, binder and conductive agent, are dispersed in a solvent such as deionized water to form a negative electrode slurry; the negative electrode slurry is coated on both sides of a negative electrode current collector such as copper foil; after baking, rolling, cutting and other processes, the negative electrode sheet can be obtained.

[0084] Optionally, in one embodiment, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material, such as a lithium-ion transition metal oxide or a ternary positive electrode material. The lithium-ion transition metal oxide includes at least one of lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate. Specifically, the ternary positive electrode material can be a high-nickel layered ternary positive electrode material.

[0085] Optionally, in one embodiment, the positive electrode further includes a conductive agent, which may include at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes, graphene, hard carbon, carbon fiber, and carbon microspheres.

[0086] In some embodiments, the positive electrode sheet is prepared as follows: the components used to prepare the positive electrode sheet, such as the positive active material including the above-mentioned positive electrode material, binder and conductive agent, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the positive electrode slurry is coated on a positive electrode current collector such as aluminum foil; after drying, rolling, die cutting and other processes, the positive electrode sheet can be obtained.

[0087] In this embodiment, the electrolyte acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be liquid, gel-like, or entirely solid. In some embodiments, the electrolyte is the aforementioned electrolyte solution, which includes an electrolyte salt and a solvent, wherein the electrolyte salt is a lithium salt.

[0088] Optionally, in one embodiment, the electrolyte comprises a lithium salt, an organic solvent, and an additive, wherein the additive comprises fluoroethylene carbonate, the organic solvent comprises at least one of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the lithium salt comprises one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonate)imide, lithium tetrafluoroborate, lithium perchlorate, and lithium trifluoromethanesulfonate.

[0089] Optionally, in one specific embodiment, the mass percentage of the additive in the electrolyte is 0.1% to 2%. Optionally, the mass percentage of the additive in the electrolyte can be one or any two of the following: 0.1%, 0.2%, 0.5%, 1%, 1.5%, and 2%.

[0090] Optionally, in one specific embodiment, the concentration of lithium salt in the electrolyte is 0.5–2 mol / L. Optionally, the concentration of lithium salt in the electrolyte can be one or any two of the following: 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.5 mol / L, and 2 mol / L.

[0091] Understandably, the battery provided in this application embodiment also includes a separator disposed between the positive electrode and the negative electrode.

[0092] In practical applications, the negative electrode sheet, positive electrode sheet, and separator are wound together to obtain a core, the core is packaged to obtain a dry cell, and the dry cell is baked and then filled with electrolyte to obtain the battery described above.

[0093] This application also proposes a secondary battery, which includes a battery obtained by the above-described method.

[0094] This application also proposes an electrical device, which includes the aforementioned secondary battery, serving as the power supply for the electrical device.

[0095] For the above-described secondary battery embodiments and electrical equipment embodiments, they include the above-described battery, which is obtained by the above-described method and can achieve the same technical effect. To avoid repetition, it will not be described again here. For relevant details, please refer to the description of the method embodiments.

[0096] The present application will be described in detail below through embodiments.

[0097] Performance testing methods

[0098] (1) DCR test procedure:

[0099] Step 1: Adjust the battery's state of charge (SOC) to 50%.

[0100] Step 2: Discharge the battery at a 0.2C rate for 30 seconds to eliminate the surface charge and ensure that the battery is in a stable state during the test. Discharge the battery at a 1C rate for 5 seconds and record the initial voltage (V1) and the final voltage (V2) of the battery at the end of the discharge.

[0101] The third step is to calculate the discharge DCR: Use the following formula to calculate the battery's discharge DCR: RDCR=(V1-V2) / I

[0102] Where I is the discharge current, V1 is the initial voltage of the battery before discharge, and V2 is the final voltage after 5 seconds of discharge.

[0103] Example 1

[0104] (1) Preparation of positive electrode sheet: The positive electrode active material lithium iron phosphate (LFP), the conductive agent acetylene black (Super P) and the binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 96:2:2 and evenly dispersed in 1-methyl-2-pyrrolidone (NMP) to form a uniform black slurry. The mixed black slurry is coated on both sides of aluminum foil, and then baked, rolled, and cut into sheets to obtain the positive electrode sheet.

[0105] (2) Preparation of negative electrode sheet: The negative electrode active material graphite, conductive agent acetylene black (Super P) and binder SBR are mixed evenly in a mass ratio of 94:3:3 and evenly dispersed in deionized water to form a uniform black slurry. The mixed slurry is coated on both sides of copper foil, and then baked, rolled, and cut into sheets to obtain the negative electrode sheet.

[0106] (3) Battery preparation: The prepared positive electrode, separator (PP separator) and negative electrode are stacked in sequence, with the separator in the middle of the positive and negative electrodes. After winding, hot pressing and shaping, the tabs are welded to obtain a bare battery. The bare battery is placed in the outer packaging aluminum-plastic film and baked in an oven at 85±10℃ for 24h. The electrolyte is injected into the dried bare battery. The lithium salt of the electrolyte is 1M LiPF6, the solvent is ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a volume ratio of 1:1:1, and the additive is fluoroethylene carbonate accounting for 0.5% of the total mass of the electrolyte.

[0107] (4) Under an ambient temperature of 30°C, the first exponentially decaying pulse voltage is applied cyclically between the positive and negative electrode plates for charging until the battery’s DCR is 50% of its initial DCR.

[0108] The amplitude of the first exponentially decaying pulse voltage satisfies: P(t) = P0(i)·e -t / τ P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is 5V; e is the base of the natural logarithm; t is time, in s; τ is 10. -1 The unit is seconds (s).

[0109] (5) Under an ambient temperature of 30°C, a second exponentially decaying pulse voltage is applied cyclically between the positive and negative electrode plates for charging until the battery’s DCR is 25% of its initial DCR.

[0110] The amplitude of the first exponentially decaying pulse voltage satisfies: P(t) = P0(i)·e -t / τ P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is 12.5V; e is the base of the natural logarithm; t is time, in s; τ is 10. -1 The unit is seconds (s).

[0111] (6) Under an ambient temperature of 30°C, the third exponentially decaying pulse voltage is applied cyclically between the positive and negative electrode plates for charging until the battery's DCR is less than 5mΩ, at which point the exponentially decaying pulse voltage charging process is stopped.

[0112] The amplitude of the first exponentially decaying pulse voltage satisfies: P(t) = P0(i)·e-t / τ P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is 35V; e is the base of the natural logarithm; t is time, in s; τ is 10. -1 The unit is seconds (s).

[0113] (7) Calculate the total immersion time.

[0114] Example 2

[0115] The difference between Example 2 and Example 1 is as follows:

[0116] In step (4), the initial amplitude P0(i) of the first exponentially decaying pulse voltage is adjusted to 4V;

[0117] In step (5), the initial amplitude P0(i) of the second exponentially decaying pulse voltage is 10V;

[0118] In step (6), the initial amplitude P0(i) of the third exponentially decaying pulse voltage is 25.

[0119] Example 3

[0120] The difference between Example 3 and Example 1 is as follows:

[0121] In step (4), the initial amplitude P0(i) of the first exponentially decaying pulse voltage is adjusted to 6V;

[0122] In step (5), the initial amplitude P0(i) of the second exponentially decaying pulse voltage is 15V;

[0123] In step (6), the initial amplitude P0(i) of the third exponentially decaying pulse voltage is 37.5V.

[0124] Examples 4-5

[0125] The difference between Examples 4 and 5 and Example 1 is that in steps (4) to (6), the ambient temperature is adjusted to 25°C and 70°C respectively.

[0126] Comparative Example 1

[0127] The difference between Comparative Example 1 and Example 1 is that in steps (4) to (6), no exponentially decaying pulse voltage is applied for charging. Instead, the battery is placed in a 30°C room and left to stand until the battery's DCR is less than 5mΩ.

[0128] Comparative Example 2

[0129] The difference between Comparative Example 2 and Example 1 is that in steps (4) to (6), no exponentially decaying pulse voltage is applied for charging. Instead, the battery is placed in a 45°C room and left to stand until the battery's DCR is less than 5mΩ.

[0130] The batteries prepared in each embodiment and comparative example were subjected to battery impedance testing and diffusion impedance testing. The test data are shown in Table 1.

[0131] Table 1

[0132] Group Total immersion time (min) Example 1 60 Example 2 80 Example 3 58 Example 4 65 Example 5 59 Comparative Example 1 240h Comparative Example 2 120h

[0133] As can be seen from the test results in Table 1, the wetting method provided in this application embodiment can effectively accelerate the wetting of the electrode sheet by the electrolyte, shorten the wetting time, and improve production efficiency.

[0134] In summary, in this embodiment, the battery wetting method involves injecting electrolyte into a battery comprising positive and negative electrodes, followed by exponentially decaying pulse voltage charging until the battery's DCR (Displacement Rate) is less than a resistance threshold, which is used to characterize the completion of battery wetting. The exponentially decaying pulse voltage not only continuously forms an electric field between the positive and negative electrodes, converting the electrical energy of lithium ions in the electrolyte into kinetic energy under the influence of the electric field force, replenishing the energy dissipated by the electrolyte's dynamic movement within the electrodes, but also helps the electrolyte overcome the interfacial energy with the electrodes, allowing the electrolyte to spread on the electrodes and accelerate wetting. This achieves rapid wetting of the battery after electrolyte injection, overcoming the bottleneck of difficult wetting of thick electrodes. Simultaneously, the energy of the exponentially decaying pulse voltage naturally decays, effectively preventing overcharging and lithium deposition on the electrodes. Therefore, it solves the problem that existing electrode wetting methods cannot effectively balance the wetting rate with the high capacity and high voltage characteristics of the battery.

[0135] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0136] The battery immersion method, secondary battery, and electrical device provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A battery wetting method, characterized in that, include: Electrolyte is injected into a battery that includes a positive electrode and a negative electrode. After the electrolyte injection is completed, the battery is subjected to exponential decay pulse voltage charging. Monitor the DCR of the battery, and stop the exponential decay pulse voltage charging process on the battery when the DCR is less than a preset resistance threshold; The step of performing exponential decay pulse voltage charging on the battery includes: The battery is charged using a first exponentially decaying pulse voltage until the DCR of the battery is 50% of its initial DCR. After the first exponentially decaying pulse voltage finishes charging, the second exponentially decaying pulse voltage is used for charging until the battery's DCR is 25% of its initial DCR. After the second exponentially decaying pulse voltage finishes charging, a third exponentially decaying pulse voltage is used for charging until the DCR of the battery is less than the preset resistance threshold. The first initial amplitude of the first exponentially decaying pulse voltage is less than the second initial amplitude of the second exponentially decaying pulse voltage, and the second initial amplitude is less than the third initial amplitude of the third exponentially decaying pulse voltage. The battery has a capacity of 20–1000 Ah, and the first initial amplitude satisfies the following relationship with the battery capacity: z=(-3*10 -5 *x 2 +0.0723*x+4.3499)*3; Where x is the capacity of the battery, in Ah; and z is the first initial amplitude, in V.

2. The battery wetting method according to claim 1, characterized in that, The amplitude of the exponentially decaying pulse voltage satisfies: P(t)=P0(i)·e -t / τ ; Where P(t) is the amplitude of the pulse voltage at time t, in V; P0(i) is the i-th initial amplitude of the pulse voltage, in V, i takes the values ​​1, 2, 3; e is the base of the natural logarithm; t is time, in s; and τ is the decay time constant of the pulse voltage, in s.

3. The battery wetting method according to claim 2, characterized in that, The initial amplitude is 3–48V.

4. The battery wetting method according to claim 1, characterized in that, The first initial amplitude is 4-6V; the second initial amplitude is 10-15V; and the third initial amplitude is 25-37.5V.

5. The battery wetting method according to claim 1, characterized in that, During the exponential decay pulse voltage charging process of the battery, the ambient temperature is 25–70°C.

6. The battery wetting method according to claim 1, characterized in that, The preset resistance threshold and the battery capacity satisfy: y = -5 * 10 -8 *x 3 +4*10 -5 *x 2 -0.014*x+2.6895; Where y is the preset resistance threshold, in mΩ.

7. The battery wetting method according to claim 1, characterized in that, The preset resistance threshold is 0.2 to 5 mΩ.

8. A secondary battery, characterized in that, The secondary battery is obtained by processing according to any one of claims 1 to 7.

9. An electrical appliance, characterized in that, The device includes the secondary battery as described in claim 8, wherein the secondary battery serves as the power supply for the electrical equipment.

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