Method and system for supplementing electrolyte in battery cell

Abstract

The invention discloses a method for supplementing electrolyte in a battery cell, which comprises the following steps: acquiring preset parameters of the battery cell, the battery cell comprising a self-repairing soft body arranged in the battery cell, and the parameters comprising the initial length of the self-repairing soft body; the length of the self-repairing software after deformation is obtained in real time through X-rays; calculating the deformation rate of the self-repairing soft body according to the length of the battery cell after the self-repairing soft body is deformed and the initial length of the self-repairing soft body; and when the deformation rate of the self-repairing soft body reaches a set threshold value, supplementing the battery cell electrolyte with a preset capacity. According to the main technical scheme and the main effects of the method, the stock change of the electrolyte is reflected in real time through geometric deformation of software, the method does not depend on traditional sudden voltage drop or off-line test, and the barren solution state is recognized earlier and more accurately.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery cells, in particular to a method and system for supplementing electrolyte in a battery cell. BACKGROUND

[0002] With the continuous development of new energy, energy storage as a product that people can use in food, clothing, shelter and transportation is attracting attention from all walks of life. How to produce long-lasting batteries that people love is the focus of the public.

[0003] In the analysis of retired batteries, the causes of failure are often attributed to the collapse of the positive and negative structures and the drying of the electrolyte. It is particularly important for the battery to have enough electrolyte throughout its life cycle. Currently, research on electrolyte is still focused on additives, such as CN119381562 A entitled "Electrolyte, battery cell, battery and electric device", which proves that fluoroethylene carbonate (FEC) can effectively reduce the interfacial resistance, delay the decomposition of electrolyte, and extend the battery life by 85%-100%. The patent "Dioxazolone and sulfurous nitrile as lithium battery electrolyte additives" invented by Tesla proposes the use of dioxazolone (DTD) and sulfurous nitrile (ODTO) as electrolyte additives, which significantly improves the capacity retention rate and reduces voltage hysteresis through a dual-additive system (such as VC+DTD, FEC+DTD), thereby extending the battery life to more than 100 million miles.

[0004] Previous studies by scholars have focused on slowing down the decay of battery cells from the theoretical perspective of electrolyte itself, but they have overlooked a crucial practical problem: the effective amount of electrolyte gradually decreases as the battery cycles, which means that the irreversible regeneration of electrolyte is a real problem, and the drying of electrolyte is one of the main reasons for the decay of lithium-ion batteries. SUMMARY

[0005] The purpose of the present application is to solve the technical problems in the prior art and provide a method and system for supplementing electrolyte in a battery cell, which can identify the amount of electrolyte in the battery cell and provide soft structure A and soft structure B to monitor the amount of electrolyte when the soft structure changes.

[0006] TECHNICAL SOLUTION

[0007] In a first aspect, the present application proposes a method for supplementing electrolyte in a battery cell, comprising the steps of:

[0008] obtaining pre-set parameters of the battery cell, wherein the battery cell includes a self-repairing soft structure located inside the battery cell, and the parameters include the initial length of the self-repairing soft structure;

[0009] real-time acquiring the length of the self-repairing soft structure after deformation through X-ray;

[0010] The deformation rate of the self-repairing soft body is calculated by the length of the self-repairing soft body after deformation and the initial length of the self-repairing soft body.

[0011] When the deformation rate of the self-repairing soft body reaches a set threshold, the electrolyte of the battery with a preset capacity is supplemented.

[0012] Preferably, the deformation rate of the self-repairing soft body is calculated by the length of the self-repairing soft body after deformation and the initial length of the self-repairing soft body, including the following formula:

[0013] ;

[0014] Wherein, L0 is the initial length of the self-repairing soft body, L1 is the length of the self-repairing soft body after deformation, and δ is the deformation rate of the self-repairing soft body.

[0015] Preferably, when the deformation rate of the self-repairing soft body reaches a set threshold, the electrolyte of the battery with a preset capacity is supplemented, including the following electrolyte supplementing rules of the battery:

[0016] ;

[0017] Wherein, Q is the amount of electrolyte supplementing.

[0018] The second aspect is an electrolyte supplementing system in a battery, which is arranged outside the battery and includes:

[0019] An X-RAY device and an electrolyte adding device;

[0020] The X-RAY device is arranged outside the battery and is used for detecting the self-repairing soft body;

[0021] The electrolyte adding device is connected with the X-RAY device and is used for supplementing electrolyte in the battery through the electrolyte adding device according to the deformation degree of the self-repairing soft body.

[0022] The third aspect is a self-repairing soft body, which includes:

[0023] A laminated composite A structure layer and a B structure layer;

[0024] The A structure layer is a lattice-like structure and is composed of cross-linked polymers, with a porosity ≤10% and a Young's modulus ≥1.0GPa;

[0025] The B structure layer is a sponge-like structure, with a porosity of 40%-50% and an average pore diameter of 1-5μm;

[0026] The thickness ratio of the A structure layer to the B structure layer is 1:(2-4);

[0027] The soft body is pre-filled with electrolyte, and the filling coefficient γ satisfies: 0.75≤γ≤0.90.

[0028] Preferably, the A structure layer comprises the following components and mass ratios:

[0029] Polyvinylidene fluoride-hexafluoropropylene copolymer is 80%-90%;

[0030] Crosslinking agent ethylene glycol dimethacrylate is 8%-15%;

[0031] Aramid nanofiber is 2%-5%;

[0032] The B structure layer comprises the following components and mass ratios:

[0033] Polyvinylidene fluoride-hexafluoropropylene copolymer is 65%-75%;

[0034] Pore-forming agent polyvinylpyrrolidone is 20%-30%;

[0035] Carbon nanotube is 1%-3%.

[0036] Preferably, the electrode liquid can follow the Fick second law in the self-repairing soft body:

[0037] ;

[0038] Wherein the diffusion coefficient D and the A and B structure porosity φ satisfy the relationship:

[0039] ;

[0040] During the liquid supplementing process, the soft body surface tension and the cell internal pressure gradient balance equation:

[0041] ;

[0042] Wherein, C is the electrolyte concentration, D is the effective diffusion coefficient, φ is the porosity, indicating the void ratio of A and B structures, D0 is the initial diffusion coefficient without porosity, σ is the surface tension, n is the unit normal vector, μ is the electrolyte viscosity, and v is the electrolyte flow rate.

[0043] In a fourth aspect, a preparation method of a self-repairing soft body structure comprises the following steps:

[0044] Step 1, preparing an A structure layer:

[0045] Mix polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene glycol dimethacrylate, and aramid nanofiber according to the mass ratio (80-90):(8-15):(2-5), and add N-methyl pyrrolidone solution to prepare a slurry with a solid content of 12%-18%;

[0046] Coated on a polyethylene terephthalate release film, with a wet film thickness of 60-100 μm;

[0047] After drying at 60-80℃, heat treatment at 110-130℃ for 1-3 hours completes cross-linking and curing.

[0048] Step 2, Prepare the B structure layer:

[0049] Polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylpyrrolidone, and multi-walled carbon nanotubes are mixed in a mass ratio of (65-75):(20-30):(1-3), and N-methylpyrrolidone solvent is added to prepare a foaming slurry with a solid content of 10%-15%.

[0050] The coating is applied to the surface of structural layer A and immediately immersed in a deionized water coagulation bath, where phase separation occurs to form a porous structure.

[0051] The solvent was removed by vacuum drying at 70-90℃ for 8-15 h. After removing the residual solvent, a sponge layer with a porosity of 45% and an average pore size of 2μm was obtained.

[0052] Step 3, Composite Processing:

[0053] The A / B double-layer structure is hot-pressed at 140-160℃ and 0.3-0.8 MPa for 20-40 seconds;

[0054] Immerse in ethanol solution for 24-72 hours to dissolve polyvinylpyrrolidone and form interconnected pores;

[0055] Step 4, Electrolyte filling:

[0056] Vacuum fill the electrolyte to saturation, controlling the filling coefficient γ = 0.75-0.90.

[0057] Preferably, in step 3, the hot pressing temperature is 150℃, the pressure is 0.5MPa, and the time is 30s.

[0058] Fifthly, this application proposes a battery cell, including a casing, positive and negative electrode plates, a separator, and an electrolyte, and further comprising:

[0059] The self-healing software as described in claims 5-6 is integrated on the surface of the separator between the positive and negative electrodes;

[0060] The positive and negative electrodes, separator, electrolyte, and self-healing software are housed within the casing.

[0061] Beneficial effects:

[0062] This invention reflects changes in electrolyte levels in real time through the geometric deformation of software, without relying on traditional voltage drop or offline testing, thus identifying low electrolyte conditions earlier and more accurately.

[0063] The system integrates algorithms that can dynamically adjust the electrolyte replenishment threshold and replenishment strategy based on the cell's operating conditions and historical data.

[0064] The soft body deformation is used as the fluid replenishment trigger signal to realize the intelligent control fluid replenishment mechanism;

[0065] Precise electrolyte replenishment can avoid problems such as lithium plating in dry areas, local overheating, and electrolyte leakage. Especially under extreme conditions such as fast charging, overcharging, and thermal shock, the presence of soft electrolytes significantly improves battery safety margin.

[0066] The soft structure is a double-layer composite (fence-like structure + A structure, sponge-like structure + B structure), which combines micromechanical behavior to form a stable curling response mechanism. It can maintain a stable physical structure under different stresses, temperatures, and magnifications, without delamination or collapse, making it suitable for various scenarios (such as energy storage, electric vehicles, power tools, etc.). Attached Figure Description

[0067] Figure 1 A schematic diagram of the method framework for this invention is provided;

[0068] Figure 2 A schematic diagram of the system structure is provided for this invention;

[0069] Figure 3 A schematic diagram of the battery cell structure is provided for this invention;

[0070] Figure 4 Schematic diagrams of different embodiments of the present invention are provided;

[0071] Figure 5 This invention provides a comparative example and schematic diagram of 3000 cycles;

[0072] Figure 6 A schematic diagram of the software structure A is provided for this invention;

[0073] Figure 7 A schematic diagram of the software structure B is provided for this invention. Detailed Implementation

[0074] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0075] Example 1

[0076] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0077] In response to the problems existing in the current technology, such as Figures 1-7 As shown, a method for replenishing electrolyte in a battery cell includes the following steps:

[0078] The system acquires preset parameters for a battery cell, wherein the battery cell includes a self-healing software disposed within the battery cell, and the parameters include the initial length of the self-healing software; it also acquires preset parameter information for the battery cell to be monitored; wherein the battery cell has a deformable self-healing software structure inside, and its material has the mechanical deformation capability to respond to changes in the electrolyte; the preset parameters include at least the initial length L0 of the self-healing software in the electrolyte saturation state, and may also include its initial volume, fill factor, installation position, etc.

[0079] The length of the self-healing software after deformation is obtained in real time using X-rays; the internal structure of the battery cell is scanned in real time using an externally integrated X-ray imaging device to obtain the length of the self-healing software in its current state after deformation. An X-ray radiography system is used to image the self-healing software embedded inside the battery cell, obtaining its geometric contour changes along its length in real time, thereby determining the actual deformation length of the software after electrolyte loss.

[0080] The deformation rate of the self-healing software is calculated by combining the length of the self-healing software after deformation with its initial length. Based on the current deformed length of the self-healing software and its initial length, the deformation rate of the self-healing software is calculated to characterize the degree of electrolyte loss.

[0081] When the deformation rate of the self-healing software reaches the set threshold, the battery electrolyte of the preset capacity is replenished.

[0082] In some specific embodiments, the method also includes injecting the battery cell into the battery cell in advance using an electrolyte adding device;

[0083] The formula for the maximum liquid capacity is as follows:

[0084] ;

[0085] V soft The volume of the software structure, in cm³, is obtained by multiplying the length, width, and thickness of the software. The length, width, and thickness of the software are preset.

[0086] ρ: Density of the electrolyte, in g / cm³;

[0087] γ: Fill factor (dimensionless), representing the proportion of electrolyte actually filled in the soft pores.

[0088] In some specific embodiments, the deformation rate of the self-healing software is calculated by combining the length of the self-healing software after deformation with the initial length of the self-healing software, including the following formula:

[0089] ;

[0090] Where L0 is the initial length of the self-healing software, L1 is the length of the self-healing software after deformation, and δ is the deformation rate of the self-healing software.

[0091] In some specific embodiments, when the deformation rate of the self-healing software reaches a set threshold, a preset capacity of battery electrolyte is replenished, including the following battery electrolyte replenishment rules:

[0092] ;

[0093] Where Q represents the amount of electrolyte added to the battery cell.

[0094] In some specific embodiments, this application proposes an in-cell electrolyte replenishment system, located outside the cell 1, comprising:

[0095] X-RAY device 2 and electrolyte addition device 3;

[0096] The X-RAY device is located outside the battery cell 1 and is used to detect self-healing software;

[0097] The electrolyte addition device is connected to the X-RAY device and is used to replenish electrolyte in the cell according to the degree of deformation of the self-healing soft body through the electrolyte addition device 3;

[0098] Both the X-RAY device 2 and the electrolyte addition device 3 are existing technologies and will not be described in detail here.

[0099] In some specific embodiments, a clamp 4 is also included, which is used to clamp the two sides of the housing 1 for fixation.

[0100] In some specific embodiments, the X-RAY device 2 integrates a miniature X-ray source (tube voltage 50kV, tube current 0.1mA) and a CMOS flat panel detector (pixel size 50μm) to achieve real-time imaging of soft body contours.

[0101] In some specific embodiments, a control unit 6 is also included, which is used to control the above-mentioned modules to implement the above-mentioned methods.

[0102] In some specific embodiments, the electrolyte addition device 3 is a storage tank and a delivery pump (not shown in the figure), through which the electrolyte is input into the battery cell.

[0103] In some specific embodiments, this application proposes a self-healing software, comprising:

[0104] Layered composite structure A and layer B;

[0105] The A-structure layer is a fence-like structure composed of cross-linked polymers, with a porosity ≤10% and Young's modulus ≥1.0 GPa;

[0106] The B-structure layer has a sponge-like structure with a porosity of 40%-50% and an average pore size of 1-5μm.

[0107] The thickness ratio of structural layer A to structural layer B is 1:(2-4);

[0108] The soft pre-filled electrolyte has a filling coefficient γ that satisfies the following condition: 0.75≤γ≤0.90.

[0109] In some specific embodiments, the shape of the software can be similar to a maple leaf, or it can be a square, a rectangle, a circle, a triangle, or a trapezoid.

[0110] In some specific embodiments, this software consists of structures A and B, where structure A is located at the bottom of structure B. Structure A has a palisade-like structure with tightly packed molecules, while structure B has a sponge-like structure with loosely packed molecules and higher porosity. As the electrolyte is consumed by gravity and the electrodes, the sponge structure B, due to its loose structure and high porosity, loses electrolyte faster and shrinks more significantly. This results in structure B shrinking more than structure A, and the inconsistent shrinkage of the two structures causes the entire software to curl towards the side that has lost less electrolyte.

[0111] In some specific embodiments, the A structural layer comprises the following components and mass ratios:

[0112] Polyvinylidene fluoride-hexafluoropropylene copolymer accounts for 80%-90%;

[0113] The crosslinking agent, ethylene glycol dimethacrylate, is 8%-15%;

[0114] Aramid nanofibers comprise 2%-5%;

[0115] The B structural layer comprises the following components and their mass ratios:

[0116] The content of polyvinylidene fluoride-hexafluoropropylene copolymer is 65%-75%;

[0117] The pore-forming agent, polyvinylpyrrolidone, is 20%-30%;

[0118] Carbon nanotubes account for 1%-3%.

[0119] In some specific embodiments, the electrode fluid can follow Fick's second law within the self-healing software:

[0120] ;

[0121] The diffusion coefficient D satisfies the following relationship with the porosity φ of structures A and B:

[0122] ;

[0123] During the fluid replenishment process, the equilibrium equation between the soft surface tension and the internal pressure gradient of the cell is as follows:

[0124] ;

[0125] Where C is the electrolyte concentration, D is the effective diffusion coefficient, φ is the porosity, representing the proportion of voids in structures A and B, D0 is the diffusion coefficient when there are no voids initially, σ is the surface tension, n is the unit normal vector, μ is the electrolyte viscosity, and v is the electrolyte flow rate.

[0126] In some specific embodiments, this application proposes a method for preparing a self-healing soft structure, including the following steps:

[0127] Step 1, prepare the A structure layer, such as Figure 6 As shown:

[0128] Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), ethylene glycol dimethacrylate (EGDMA), and aramid nanofibers are mixed in a mass ratio (ANF) of (80-90):(8-15):(2-5). In some embodiments, PVDF-HFP:EGDMA:ANF = 85:10:5 is used. N-methylpyrrolidone (NMP) solution is added to prepare a slurry with a solid content of 12%-18%.

[0129] Coated onto polyethylene terephthalate release film, with a wet film thickness of 60-100μm;

[0130] After drying at 60-80℃, heat treatment at 110-130℃ for 1-3 hours completes cross-linking and curing.

[0131] Step 2, prepare the B structure layer, such as Figure 7 As shown:

[0132] Polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyvinylpyrrolidone (PVP), and multi-walled carbon nanotubes (MWCNT) are mixed in a mass ratio of (65-75):(20-30):(1-3), and N-methylpyrrolidone solvent is added to prepare a foaming slurry with a solid content of 10%-15%.

[0133] The coating is applied to the surface of structural layer A and immediately immersed in a deionized water coagulation bath, where phase separation occurs to form a porous structure.

[0134] The solvent was removed by vacuum drying at 70-90℃ for 8-15 h. After removing the residual solvent, a sponge layer with a porosity of 45% and an average pore size of 2μm was obtained.

[0135] Step 3, Composite Processing:

[0136] The A / B double-layer structure is hot-pressed at 140-160℃ and 0.3-0.8 MPa for 20-40 seconds;

[0137] Immerse in ethanol solution for 24-72 hours to dissolve polyvinylpyrrolidone and form interconnected pores;

[0138] Step 4, Electrolyte filling:

[0139] Vacuum fill the electrolyte to saturation, controlling the filling coefficient γ = 0.75-0.90.

[0140] In some specific embodiments, the A structure (fence-like structure) is made of highly cross-linked polyvinylidene fluoride (PVDF), whose molecular chains form a rigid network through strong hydrogen bonds, with a Young's modulus of 1.2 GPa, allowing only electrolyte molecules to exist in monolayer adsorption form.

[0141] Structure B (sponge-like structure) uses low-density polyethylene (LDPE) and nano-silica composite material with a porosity of 78%. The electrolyte is filled in a capillary condensation state. The Laplace pressure difference driven by surface tension (ΔP=2γ / r, where γ is the surface tension and r is the pore size) causes Structure B to produce a volume shrinkage of 3-5 times that of Structure A11 when the electrolyte is lean.

[0142] When the electrolyte is missing, the porosity of structure B drops from 78% to 42%, resulting in a vertical shrinkage of ΔL = ε × L0 (ε is the strain and L0 is the initial length), while the strain of structure A is only 0.8ε, generating a curling moment M = E × I × Δε (E is the elastic modulus and I is the moment of inertia of the section).

[0143] In some specific embodiments, in step 3, the hot pressing temperature is preferably 150°C, the pressure is 0.5 MPa, and the time is 30 s.

[0144] In some embodiments, this application provides a battery cell, including a housing 7, positive and negative electrode plates 8, a separator 9, and an electrolyte 10, and further comprising:

[0145] The self-healing software as described in claims 5-6 is integrated on the surface of the separator between the positive and negative electrodes;

[0146] The positive and negative electrode plates 8, the separator 9, the electrolyte 10, and the self-healing software are located inside the housing.

[0147] Example 1: The cell specifications can be set as LFP / graphite system, with a capacity of 100Ah and a soft size of 10mm×2mm×0.5mm (A / B structure thickness ratio 1:3).

[0148] The test conditions were a 25℃ constant temperature chamber, 1C charge and discharge, and accelerated aging was carried out using 45℃ high temperature storage.

[0149] The fluid replacement strategy is as follows:

[0150] ;

[0151] After replenishing the electrolyte, the solution was immersed in a low current of 0.1C for 2 hours to allow the electrolyte to fully penetrate into the pores of the B structure.

[0152] In addition, a single 300μL electrolyte replenishment of a cell whose capacity had decayed to 80% after 2000 cycles restored its capacity to 92%, and it maintained more than 90% capacity in the subsequent 500 cycles, or 2500 cycles.

[0153] In some specific embodiments, the A-structure (fence-like structure) is prepared.

[0154] Slurry preparation: Mix PVDF-HFP:EGDMA:ANF at a mass ratio of 85:10:5, and add NMP solvent to adjust to a slurry with a solid content of 15%.

[0155] Coating process: A slotted coating machine is used to coat the PET release film, controlling the wet film thickness to 80μm, and then the film is dried with hot air at 60℃ to form a dense film layer.

[0156] Cross-linking and curing: Heat treatment at 120℃ for 2 hours to allow EGDMA to complete the cross-linking reaction and form a three-dimensional mesh fence structure.

[0157] Preparation of B-structure (sponge-like structure)

[0158] Foaming slurry preparation: Mix PVDF-HFP and PVP at a mass ratio of 70:30, add MWCNT (2wt%) and NMP solvent, with a solid content of 12%.

[0159] Phase transformation molding: PVP is applied to the surface of structure A by a doctor blade and immediately immersed in a deionized water coagulation bath, where the PVP phase separates to form a porous structure.

[0160] Post-treatment: Vacuum drying at 80℃ for 12h to remove residual solvent, yielding a sponge layer with a porosity of 45% and an average pore size of 2μm.

[0161] Double-layer composite structure

[0162] Hot-press composite: The A / B double-layer structure is hot-pressed at 150℃ and 0.5MPa for 30s to allow the interface molecular chains to diffuse and fuse.

[0163] Pore-forming agent removal: The composite membrane was immersed in an ethanol solution for 48 hours to completely dissolve the PVP and form a through-pore structure.

[0164] Electrolyte prefilling: Vacuum-filled electrolyte until the soft body is saturated, and the filling coefficient γ=0.85 (V_electrolyte=0.85×V_soft body pores) is controlled by weighing method.

[0165] Electrolyte compensation test

[0166] Accelerated aging: The soft deformation was measured every 50 cycles of 3C charge-discharge cycle.

[0167] Liquid replenishment strategy: When the deformation reaches 20%, inject 0.1 mL of electrolyte through the microchannel reserved in the software and record the voltage recovery time (it should be ≤10 min).

[0168] Cyclic life assessment

[0169] Long-term test: 3000 cycles of 1C were performed at 25℃, and the volume retention rate of the rehydration group and the control group was compared (the rehydration group should be ≥90%, and the control group should be ≤75%).

[0170] Rate performance: Test the 5C discharge capacity retention rate (≥90% for the replenished fluid group, ≤85% for the control group).

[0171] Security verification

[0172] Overcharge test: Overcharge to 4.5V at 2C and monitor for software cracking and leakage (there should be no electrolyte leakage).

[0173] Thermal shock: Cycle 10 times from -20℃ to 60℃ to check the reliability of the adhesion between the soft body and the electrode (peel strength should be ≥5N / m).

[0174] The software prepared by the above process can realize online monitoring and automatic compensation of electrolyte volume, so that the capacity decay of the cell is ≤5% after 3000 cycles, which is significantly better than traditional cells (which usually decay by 10%-15%).

[0175] Comparative Example 1 (Traditional battery cell without flexible components)

[0176] Parameter settings: Conventional cell structure (no soft body, only separator + electrode), initial electrolyte injection amount: 3.5g / Ah (theoretical requirement).

[0177] Test method:

[0178] 1. Conduct a 1C cycle test at 25℃, and disassemble the cell every 100 cycles to observe the wettability of the electrode sheets.

[0179] 2. Monitor the change in cell internal resistance using the electrochemical impedance spectroscopy (EIS) method.

[0180] result:

[0181] Cyclic performance: After 3000 cycles, the capacity retention rate is 68%, and the internal resistance increases to 3.2 times the initial value.

[0182] Electrode condition: After 300 cycles, a significant dehydrated area (width > 2 mm) appeared at the edge of the electrode, and the diaphragm was locally dried out.

[0183] Deformation monitoring: Electrolyte deficiency cannot be determined by the degree of soft deformation; it can only be indirectly determined by a sudden drop in voltage (<2.5V).

[0184] Conclusion: Without flexible cells, active electrolyte replenishment is impossible, and cycle degradation is mainly caused by uneven electrolyte distribution.

[0185] Comparative Example 2 (Software available but parameters not optimized)

[0186] Parameter settings: Soft structure: Structure A (PVDF-HFP single layer, no crosslinking agent), Structure B (PVDF-HFP + 30% PVP foaming).

[0187] Porosity: Structure B has 60% (too high), while Structure A has no fence effect;

[0188] Fill factor γ = 0.95 (overfill);

[0189] Test method:

[0190] 1.1C Cyclic Test: The software deformation is detected by XRY every 50 cycles.

[0191] 2. When the deformation reaches 25%, manually add 0.2 mL of liquid.

[0192] result:

[0193] Deformation degree and cycle correlation: After 2000 cycles, the deformation degree reached 25%, but the volume only recovered to 92% after replenishment (first replenishment), and replenishment failed after 2500 cycles.

[0194] Cause of failure: Excessive shrinkage of structure B caused the soft material to separate from the electrode. XRAY images showed that the soft material curled into a "C" shape, but the electrode was irreversibly damaged.

[0195] Cyclic performance: After 3000 cycles, the capacity retention rate was 55%, which was lower than that of Comparative Example 1 (due to increased side reactions caused by frequent replenishment).

[0196] Conclusion: Although the software with unoptimized parameters can trigger fluid replenishment, structural instability leads to poor long-term performance.

[0197] Example 1 (Optimization of porosity and filling factor)

[0198] Parameter settings:

[0199] Soft structures: Structure A (PVDF-HFP + 10% EGDMA crosslinking), Structure B (PVDF-HFP + 20% PVP foaming).

[0200] Porosity: Structure B 45% (optimized value), Structure A 5% (dense fence);

[0201] Fill factor γ = 0.85 (precise control);

[0202] Test method:

[0203] 1.1C Cyclic test, with the deformation threshold set to 15% (XRY image bending length / total length ≥ 15%).

[0204] 2. When the threshold is reached, 0.1 mL of fluid is automatically replenished through the soft microchannel.

[0205] result:

[0206] Deformation degree and cycle correlation: The first replenishment occurred at 450 cycles (deformation degree 16%), and the volume recovered to 98% after replenishment.

[0207] Cyclic performance: After 3000 cycles, the capacity retention rate is 89%, and the internal resistance only increases to 1.8 times the initial value.

[0208] Software status: XRY shows that the software exhibits a uniform wavy deformation and remains in contact with the electrode.

[0209] Conclusion: After optimizing the porosity and filling coefficient, the soft body deformation and electrolyte consumption are precisely matched, and the electrolyte replenishment effect is significant.

[0210] Example 2 (Adjusting crosslinking density and structural stability)

[0211] Parameter settings:

[0212] Soft structures: Structure A (PVDF-HFP + 15% EGDMA crosslinking), Structure B (PVDF-HFP + 25% PVP foaming).

[0213] Crosslinking density: 8% swelling degree of structure A (to improve mechanical strength);

[0214] The fill factor γ = 0.80;

[0215] Test method:

[0216] 1.2C high-rate cycling test accelerates electrolyte consumption.

[0217] 2. The deformation threshold is set to 20% (to adapt to high magnification conditions).

[0218] result:

[0219] Deformation degree and cycle correlation: The first replenishment occurred at 200 cycles (deformation degree 22%), and the volume recovered to 95% after replenishment.

[0220] Cyclic performance: After 1000 cycles, the capacity retention rate is 85%, and the internal resistance stability at high rates is better than that of Example 1.

[0221] Soft state: The A-structure fence layer effectively suppresses excessive shrinkage, and XRY shows that the soft body exhibits uniform "S"-shaped deformation.

[0222] Conclusion: Increasing the crosslinking density enhances the stability of the soft structure and enables it to adapt to long-term cycling under high-rate conditions.

[0223] Example 3 (Dynamic Filling Coefficient and Intelligent Fluid Replenishment)

[0224] Parameter settings:

[0225] Soft structures: Structure A (PVDF-HFP + 12% EGDMA crosslinking), Structure B (PVDF-HFP + 18% PVP foaming).

[0226] The fill factor γ = 0.75-0.90 (dynamically adjusted with the number of cycles);

[0227] Liquid replenishment strategy: For every 5% increase in deformability, the liquid replenishment volume increases by 0.05 mL.

[0228] Test method:

[0229] 1. Simulate extreme working conditions (3C fast charging + 45℃ high temperature).

[0230] 2. Real-time monitoring of software deformation via XRY, and linkage with the fluid replenishment system.

[0231] result:

[0232] Deformation degree and cycle correlation: The first replenishment occurred at 150 cycles (deformation degree 18%), and replenishment was performed once every 100 cycles thereafter.

[0233] Cyclic performance: 92% volume retention after 3000 cycles (total replenishment volume 0.35 mL), internal resistance increase at high temperature <20%.

[0234] Software status: The dynamic fill factor keeps the software moderately expanded, and XRY shows that the degree of deformation is linearly related to electrolyte consumption.

[0235] Conclusion: The dynamic filling coefficient and intelligent electrolyte replenishment strategy enable precise management of electrolyte and significantly improve cycle life under extreme conditions.

[0236] By combining Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, in combination Figure 5 It can be seen that the soft deformation degree is strongly correlated with the electrolyte consumption, and the threshold setting needs to be optimized by combining porosity and cross-linking density; precise electrolyte replenishment can restore the capacity to more than 95% and delay the rise of internal resistance; dynamic filling coefficient and intelligent electrolyte replenishment strategy are the core to achieving "zero decay long cycle" of battery cells.

[0237] The above description is merely a specific implementation of the embodiments of the present invention, but the protection scope of the embodiments of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of the present invention should be covered within the protection scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention should be determined by the protection scope of the claims.

Claims

1. A method for replenishing electrolyte in a battery cell, characterized in that, Including the following steps: Obtain preset parameters for the battery cell, wherein the battery cell includes self-healing software disposed within the battery cell, and the parameters include the initial length of the self-healing software; The length of the self-healing software after deformation is obtained in real time using X-rays; The deformation rate of the self-healing software is calculated by the length of the self-healing software after deformation and the initial length of the self-healing software. When the deformation rate of the self-healing software reaches the set threshold, the battery electrolyte of the preset capacity is replenished.

2. The method according to claim 1, characterized in that, The deformation rate of the self-healing software is calculated by combining the length of the self-healing software after deformation with the initial length of the self-healing software, using the following formula: ； Where L0 is the initial length of the self-healing software, L1 is the length of the self-healing software after deformation, and δ is the deformation rate of the self-healing software.

3. The method according to claim 2, characterized in that, When the deformation rate of the self-healing software reaches a set threshold, a preset capacity of battery electrolyte is replenished, including the following battery electrolyte replenishment rules: ； Where Q represents the amount of electrolyte added to the battery cell.

4. A battery cell electrolyte replenishment system, applicable to the method described in any one of claims 1-3, disposed outside the battery cell, characterized in that, include: X-RAY device and electrolyte addition device; The X-RAY device is located on the outside of the battery cell and is used to detect self-healing software; The electrolyte addition device is connected to the X-RAY device and is used to replenish electrolyte in the cell according to the degree of deformation of the self-healing software.

5. A self-healing software as described in any one of claims 1-4, characterized in that, include: Layered composite structure A and layer B; The A-structure layer is a fence-like structure composed of cross-linked polymers with a porosity ≤10% and a Young's modulus ≥1.0 GPa; The B-structure layer has a sponge-like structure with a porosity of 40%-50% and an average pore size of 1-5μm. The thickness ratio of structural layer A to structural layer B is 1:(2-4); The soft pre-filled electrolyte has a filling coefficient γ that satisfies the following condition: 0.75≤γ≤0.

90.

6. The self-healing software as described in claim 5, characterized in that: The A structural layer comprises the following components and their mass ratios: Polyvinylidene fluoride-hexafluoropropylene copolymer accounts for 80%-90%; The crosslinking agent, ethylene glycol dimethacrylate, is 8%-15%; Aramid nanofibers comprise 2%-5%; The B structural layer comprises the following components and their mass ratios: The content of polyvinylidene fluoride-hexafluoropropylene copolymer is 65%-75%; The pore-forming agent, polyvinylpyrrolidone, is 20%-30%; Carbon nanotubes account for 1%-3%.

7. The self-healing software as described in claim 5, characterized in that: Electrode fluid can follow Fick's second law within self-healing software: ； The diffusion coefficient D satisfies the following relationship with the porosity φ of structures A and B: ； During the fluid replenishment process, the equilibrium equation between the soft surface tension and the internal pressure gradient of the cell is as follows: ； Where C is the electrolyte concentration, D is the effective diffusion coefficient, φ is the porosity, representing the proportion of voids in structures A and B, D0 is the diffusion coefficient when there are no voids initially, σ is the surface tension, n is the unit normal vector, μ is the electrolyte viscosity, and v is the electrolyte flow rate.

8. A method for preparing a self-healing soft structure as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1, Prepare the A structure layer: Polyvinylidene fluoride-hexafluoropropylene copolymer, ethylene glycol dimethacrylate, and aramid nanofibers are mixed in a mass ratio of (80-90):(8-15):(2-5), and N-methylpyrrolidone solution is added to prepare a slurry with a solid content of 12%-18%. Coated onto polyethylene terephthalate release film, with a wet film thickness of 60-100μm; After drying at 60-80℃, heat treatment at 110-130℃ for 1-3 hours completes cross-linking and curing. Step 2, Prepare the B structure layer: Polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylpyrrolidone, and multi-walled carbon nanotubes are mixed in a mass ratio of (65-75):(20-30):(1-3), and N-methylpyrrolidone solvent is added to prepare a foaming slurry with a solid content of 10%-15%. The coating is applied to the surface of structural layer A and immediately immersed in a deionized water coagulation bath, where phase separation occurs to form a porous structure. The solvent was removed by vacuum drying at 70-90℃ for 8-15 hours. After removing the residual solvent, a sponge layer with a porosity of 45% and an average pore size of 2μm was obtained. Step 3, Composite Processing: The A / B double-layer structure is hot-pressed at 140-160℃ and 0.3-0.8MPa for 20-40s; Immerse in ethanol solution for 24-72 hours to dissolve polyvinylpyrrolidone and form interconnected pores; Step 4, Electrolyte filling: Vacuum fill the electrolyte to saturation, controlling the filling coefficient γ = 0.75-0.

90.

9. The preparation method according to claim 8, characterized in that, In step 3, the preferred hot pressing temperature is 150℃, the pressure is 0.5MPa, and the time is 30s.

10. A battery cell, comprising a housing, positive and negative electrodes, a separator, and an electrolyte, characterized in that: Also includes: The self-healing software as described in any one of claims 1-9 is integrated on the surface of the separator between the positive and negative electrodes; The positive and negative electrodes, separator, electrolyte, and self-healing software are housed within the casing.

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