A composite shell structure for lossless liquid supplement of a power battery, a power battery and a liquid supplement system

Abstract

The application discloses a composite shell structure for lossless liquid supplement of a power battery, a power battery and a liquid supplement system, and belongs to the technical field of lithium ion battery maintenance equipment. The composite shell structure is a core technical scheme, is arranged in a sealing position of a power battery shell in a manner from outside to inside, and sequentially stacks a light-transmitting outer layer, a light-absorbing intermediate layer and a metal inner layer with a bottom non-penetrating thin-wall blind hole. The composite shell structure solves the core pain point that permanent structure damage is caused by puncture in the prior art and lossless repeated liquid supplement cannot be realized. The matched power battery and the liquid supplement system realize lossless repeated liquid supplement of the battery in a whole life cycle, have a compact structure, are completely compatible with an existing battery mass production process, and can be widely applied to various square power batteries and energy storage batteries.

Description

Technical Field

[0001] This invention belongs to the technical field of lithium-ion battery maintenance equipment, and more specifically, relates to a composite shell structure for non-destructive fluid replenishment of power batteries, a power battery and a fluid replenishment system. Background Technology

[0002] With the continued advancement of the dual-carbon strategy, the new energy vehicle industry and the electrochemical energy storage industry have entered a period of rapid development. Lithium-ion batteries and sodium-ion batteries, as core energy storage devices, have seen their cycle life, total life cycle cost, and long-term operational safety become core competitive indicators in the industry. During the charge-discharge cycle of a power battery throughout its entire life cycle, the electrolyte will continuously suffer irreversible losses: on the one hand, the growth and repair of the solid electrolyte interface film will continuously consume the lithium salts and organic solvents in the electrolyte; on the other hand, the high-temperature environment and abnormal operating conditions such as overcharging and over-discharging during long-term battery operation will accelerate the decomposition and vaporization of the electrolyte, ultimately leading to insufficient electrolyte in the battery. This directly causes an increase in battery internal resistance, a decrease in charge-discharge capacity, and a significant reduction in cycle life. In severe cases, it may even lead to safety accidents due to local lithium plating and thermal runaway.

[0003] Currently, industry solutions for electrolyte loss mainly focus on one-time electrolyte replenishment after battery production and after-sales puncture-based electrolyte replenishment. However, these solutions face unresolved technical bottlenecks in practical industrial applications. Mechanical puncture-based electrolyte replenishment is the most mainstream after-sales method. This method uses a rigid needle to puncture the battery casing to create a replenishment channel, and then seals the puncture with sealant after replenishment. However, this method has fatal flaws: mechanical puncture causes permanent structural damage to the battery casing, stress concentration at the puncture site, and the expansion and contraction cycles of long-term charging and discharging can cause cracks at the seal, leading to leakage, air ingress, and other problems. The reliability of secondary sealing is extremely poor, and it can only achieve single-time replenishment, failing to meet the needs of multiple replenishments throughout the battery's lifespan. Furthermore, metal fragments generated during the puncture process can easily fall into the battery, causing internal short circuits and posing a significant safety hazard.

[0004] Another existing solution involves pre-installing an online liquid replenishment valve before the battery leaves the factory. This solution integrates the valve structure onto the battery casing to perform the liquid replenishment operation. However, this solution significantly increases the structural complexity and overall volume of the battery, reducing the energy density of the battery system. Furthermore, the valve's dynamic sealing structure poses a long-term leakage risk, which actually reduces the battery's long-term operational safety. Therefore, it cannot be widely applied in scenarios with extremely high requirements for volume density and safety, such as passenger vehicle power batteries and energy storage batteries. In addition, the few existing laser-based liquid replenishment solutions do not have battery casing structures designed to adapt to the working characteristics of laser liquid replenishment. The laser needs to directly penetrate the full thickness of the battery casing, easily creating a large heat-affected zone, causing casing deformation and thermal damage to internal electrodes. Moreover, the inconsistent openings prevent repeated liquid replenishment operations.

[0005] In summary, existing power battery electrolyte replenishment technologies consistently fail to simultaneously address the core requirements of non-destructive drilling, no permanent structural damage, repeated electrolyte replenishment, long-term reliable sealing, and strong mass production compatibility. They cannot meet the maintenance needs throughout the entire lifecycle of power batteries, becoming a core technological bottleneck restricting the industrialization of long-life power batteries. This technical solution originates from a key technology R&D project for sodium-ion batteries, and is optimized to address the aforementioned industry pain points, aiming to provide a scalable, non-destructive, reusable electrolyte replenishment solution for power batteries. Summary of the Invention

[0006] The purpose of this invention is: 1. Addressing the core pain points of the industry, such as permanent structural damage to battery casings caused by existing puncture-based fluid replenishment technologies and the inability to achieve non-destructive repeated fluid replenishment, this paper provides a composite casing structure for non-destructive fluid replenishment of power batteries. Through a three-layer collaborative stacked structure design, combined with laser technology, controllable openings without permanent damage are achieved, fundamentally solving the core defects of existing technologies and providing a basic carrier for repeated fluid replenishment of power batteries. 2. A power battery with refillable electrolyte is provided. By integrating the above-mentioned composite shell structure, the power battery has maintainability throughout its entire life cycle after leaving the factory, extending the battery cycle life, while being fully compatible with existing mass production processes. 3. Provide a laser-induced microchannel non-destructive fluid replenishment system for power batteries. Based on the above-mentioned composite shell structure, it forms a complete set of equipment with a closed loop of opening, fluid injection and sealing, realizing standardized and automated non-destructive fluid replenishment operation, and is suitable for large-scale after-sales operation and maintenance scenarios. To achieve the above objectives, in a first aspect, the present invention provides a composite shell structure for non-destructive fluid replenishment of a power battery. The composite shell structure is integrated onto the battery shell of the power battery, forming a sealed portion of the battery shell. The composite shell structure is provided with a light-transmitting outer layer, a light-absorbing intermediate layer, and a metal inner layer stacked sequentially from the outside to the inside, with the inner surface of the metal inner layer facing the internal cavity of the power battery. The inner metal layer has blind holes with the openings facing the light-absorbing intermediate layer, and the bottom of the blind holes has a thin-walled structure.

[0007] Optionally, the light-absorbing intermediate layer is a hexagonal close-packed solid micropillar array structure, with the solid micropillars arranged in a continuous manner along the stacking direction of the three-layer structure; the blind hole is an inverted cone shape, and the blind hole is coaxially arranged with the corresponding single solid micropillar in the light-absorbing intermediate layer to form a preset opening position that allows laser penetration.

[0008] Optionally, the material of the light-transmitting outer layer is a light-transmitting insulating ceramic material with a thickness of 0.8-1.2 mm, a light transmittance of 90-95% for 1064 nm wavelength laser, and a bending strength of 350-400 MPa.

[0009] Optionally, the light-absorbing intermediate layer is made of polyimide composite carbon black-graphene material with a thickness of 0.2-0.4 mm, a porosity of 30±5%, an absorption rate of 93-97% for 1064 nm wavelength laser, and a single-point ablation threshold of 5 mJ / cm².

[0010] Optionally, the diameter of the micropillars in the solid micropillar array is 80-120 μm, the center-to-center array spacing between adjacent micropillars is 250-350 μm, and the height of the micropillars is consistent with the thickness of the light-absorbing intermediate layer.

[0011] Optionally, the inner metal layer is made of aluminum alloy sheet with a thickness of 0.5-0.7 mm.

[0012] Optionally, the diameter of the blind hole is 70-90μm, the depth is 300±10μm, the cone angle is 80-88°, and the thickness of the bottom of the blind hole that does not penetrate the thin wall is 40-60μm.

[0013] Secondly, the present invention provides a power battery that can be repeatedly replenished with electrolyte, comprising a battery casing and a battery cell, wherein the battery casing integrates the composite casing structure described in the first aspect for non-destructive electrolyte replenishment of the power battery.

[0014] Thirdly, this invention provides a laser-induced microchannel non-destructive fluid replenishment system for power batteries. It includes the composite shell structure for non-destructive fluid replenishment of power batteries, the pulsed fiber laser processing module, the fluid injection module, and the sealing and repair module as described in the first aspect; The pulsed fiber laser processing module is disposed on the outside of the light-transmitting outer layer of the composite shell structure. It is used to emit laser to penetrate the light-transmitting outer layer, ablate the light-absorbing intermediate layer, and break through the thin-walled structure of the blind hole in the metal inner layer to form a microchannel connecting the inside of the power battery. The electrolyte injection module is used to seal and connect with the inlet of the microchannel and inject electrolyte into the power battery in a quantitative manner. The sealing and repair module is used to apply a sealing coating to the entrance of the microchannel after the liquid injection is completed to achieve an airtight seal.

[0015] Optionally, the pulsed fiber laser processing module uses a three-cascaded fiber laser with a laser wavelength of 1060-1070nm, a single pulse energy of 5-15mJ, a repetition frequency of 1-20kHz, a focused spot diameter of 25-35μm, and a pulse width of 50-200ns.

[0016] Optionally, the sealing coating has a two-layer composite structure, comprising a base sealing layer and a reinforcing sealing layer from the inside out; The basic sealing layer is made of polyurethane-urea material doped with nano-SiO2 particles, with a thickness of 40-50 μm and a nano-SiO2 doping amount of 1-3 wt%. The reinforced sealing layer is made of fluorine-modified polyurethane with a fluorine content of 8-12 wt% and a thickness of 30-40 μm.

[0017] Compared with the prior art, the present invention has the following advantages: 1. It fundamentally solves the core pain point of permanent structural damage in existing liquid replenishment technologies. Through a three-layer synergistic structure of a light-transmitting outer layer, a light-absorbing middle layer, and a metal inner layer with a non-penetrating thin-walled blind hole, it achieves laser-controlled non-destructive opening. During liquid replenishment, only the laser needs to penetrate the micron-level thin wall at the bottom of the blind hole to form a liquid replenishment channel. There is no need to puncture the entire battery casing, resulting in no permanent structural damage. This provides a basic carrier for the large-scale implementation of repeated liquid replenishment of power batteries, and completely breaks through the industry technical bottleneck that existing technologies cannot simultaneously ensure the integrity of the casing seal and the reusability of liquid replenishment.

[0018] 2. By integrating the above-mentioned composite shell structure, the power battery is made maintainable throughout its entire life cycle after leaving the factory. The electrolyte lost during the battery cycle can be continuously replenished through multiple replenishments, which can significantly extend the battery cycle life and reduce the cost of using the battery throughout its entire life cycle. At the same time, the composite shell structure is fully compatible with the existing mass production welding and packaging processes of power batteries, without the need for large-scale modification of existing production lines, and the cost of industrialization is extremely low.

[0019] 3. Based on the above composite shell structure, a complete set of liquid replenishment equipment with a closed-loop process of opening, liquid injection and sealing is formed. Each functional module is precisely matched with the core design of the composite shell structure, which can realize standardized and automated non-destructive liquid replenishment operation, ensure the consistency and reliability of the liquid replenishment process, avoid performance fluctuations and safety hazards caused by manual operation, and perfectly adapt to large-scale battery after-sales maintenance, cascade utilization and other commercial scenarios.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0022] Figure 1 A cross-sectional schematic diagram of a composite shell structure for non-destructive fluid replenishment of a power battery, according to an embodiment of the present invention, is shown.

[0023] Figure 2A cross-sectional structural diagram of the metal inner layer according to an embodiment of the present invention is shown.

[0024] Figure 3 One of the schematic diagrams of a hexagonal close-packed solid micropillar array structure of the light-absorbing intermediate layer according to an embodiment of the present invention is shown.

[0025] Figure 4 The second schematic diagram shows a hexagonal close-packed solid micropillar array structure of the light-absorbing intermediate layer according to an embodiment of the present invention.

[0026] Figure 5 A schematic diagram of the structure of the laser-induced microchannel non-destructive fluid replenishment system for power batteries according to an embodiment of the present invention is shown.

[0027] Figure 6 A schematic diagram of the liquid injection module according to an embodiment of the present invention is shown.

[0028] Figure 7 A schematic diagram of the sealing coating structure according to an embodiment of the present invention is shown.

[0029] Explanation of reference numerals in the attached figures: 100. Composite shell structure; 110. Transparent outer layer; 120. Light-absorbing intermediate layer; 130. Metal inner layer; 131. Blind hole; 132. Thin-walled structure; 200. Pulsed fiber laser processing module; 300. Injection module; 310. Flexible injection nozzle; 400. Sealing coating; 410. Base sealing layer; 420. Reinforcing sealing layer; 500. Battery casing. Detailed Implementation

[0030] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0031] The composite shell structure 100 for non-destructive electrolyte replenishment of power batteries disclosed in this invention has a core innovation in achieving laser-controlled non-destructive drilling and repeated sealing repair through a three-layer aligned and stacked structural design. Its core principle is as follows: the laser light passes through the light-transmitting outer layer 110 and is absorbed by the light-absorbing intermediate layer 120, generating localized high temperatures that precisely penetrate the thin-walled structure 132 of the blind hole 131 in the inner metal layer 130, forming a microchannel connecting the battery's interior (in this specification, the microchannel refers to the micron-level fluid channel connecting the internal cavity of the power battery to the outside world formed after the bottom thin wall of the blind hole 131 in the inner metal layer 130 is ablated by a pulsed fiber laser; the entrance of the microchannel refers to the opening end of the microchannel on the outer surface of the light-transmitting outer layer 110). After electrolyte injection, the microchannel is sealed by a sealing coating 400, restoring the battery's airtightness. The laser drilling, electrolyte injection, and sealing process can be repeated for subsequent electrolyte replenishment, achieving non-destructive repeated electrolyte replenishment.

[0032] It should be noted that the composite housing structure 100 described in this invention is not limited to the top cover of the power battery. It can be integrated into any sealed part of the power battery housing 500, including the side wall and the bottom. As long as it constitutes a sealed part of the battery housing 500 and the inner side of the metal inner layer 130 faces the internal cavity of the battery, the technical effect of this invention can be achieved. The following embodiments use the top cover as a preferred solution for illustration only, and are not intended to limit the scope of protection of this invention.

[0033] The composite shell structure 100 of the present invention has a total thickness of 1.5-2.3mm ± 0.05mm, and is composed of a light-transmitting outer layer 110, a light-absorbing intermediate layer 120, and a metal inner layer 130 stacked sequentially from the outside to the inside. The specific design is as follows: The light-transmitting outer layer 110 is made of light-transmitting insulating ceramic material, preferably alumina ceramic, with a thickness ranging from 0.8 to 1.2 mm, preferably 1.0 ± 0.05 mm; the light transmittance to 1064 nm wavelength laser ranges from 90 to 95%, and the bending strength ranges from 350 to 400 MPa.

[0034] This layer performs three core functions: laser transmission, structural protection, and insulation protection. Alumina ceramic is a mature insulation and protection material in the field of power batteries. It has extremely high structural strength and corrosion resistance, which can meet the requirements of battery protection and mechanical impact. At the same time, it achieves high transmittance for specific wavelength lasers, ensuring that the laser energy penetrates and enters without significant loss.

[0035] The light-absorbing intermediate layer 120 is a solid micropillar array structure with hexagonal close packing (in this specification, hexagonal close packing means that the centers of the solid micropillars are periodically and uniformly arranged in a regular hexagonal grid on the plane of the light-absorbing intermediate layer 120). The solid micropillars penetrate the entire thickness of the light-absorbing intermediate layer 120 along the stacking direction. The micropillars are cylindrical or regular hexagonal prism structures. The diameter of the micropillars is 80-120μm, the center-to-center distance between adjacent micropillars is 250-350μm, and the upper and lower end faces of the micropillars are tightly attached to the light-transmitting outer layer 110 and the metal inner layer 130, respectively.

[0036] The light-absorbing intermediate layer 120 is made of polyimide composite carbon black-graphene material, with a thickness ranging from 0.2 to 0.4 mm and a porosity of 30 ± 5%. Its absorption rate for 1064 nm wavelength laser light ranges from 93 to 97%, and its single-point ablation threshold is 5 mJ / cm². This array structure can uniformly disperse laser energy, control the heat-affected zone, and simultaneously utilize the interlayer pores to discharge laser ablation products, avoiding channel blockage and ensuring the ability to repeatedly open holes.

[0037] The inner metal layer 130 uses aluminum alloy sheet commonly used in power batteries, with a thickness of 0.5-0.7mm, and is compatible with the conventional welding and packaging processes of the battery casing 500.

[0038] Blind holes 131 are arrayed on the surface of the inner metal layer 130. The blind holes 131 are inverted conical in shape, with their openings facing the light-absorbing intermediate layer 120 and a thin wall not penetrated at the bottom. The diameter of the blind holes 131 is 70-90μm, the depth is 300±10μm, the cone angle is 80-88°, and the thickness of the thin wall at the bottom is 40-60μm. Each blind hole 131 is coaxially corresponding to a single solid micropillar at the corresponding position in the light-absorbing intermediate layer 120, forming a preset opening position for precise laser alignment.

[0039] The inverted conical structure facilitates laser focusing and liquid replenishment. Under normal conditions, the thin-walled structure is completely sealed, and during liquid replenishment, the laser precisely penetrates the surface, allowing for opening as needed without damaging the main body.

[0040] The laser-induced microchannel non-destructive fluid replenishment system for power batteries disclosed in this invention includes a pulsed fiber laser processing module 200, a fluid injection module 300, a sealing and repair module, and a central controller and a vision positioning system. The pulsed fiber laser processing module 200 uses a fiber laser with a working wavelength of 1060-1070nm, a single pulse energy of 5-15mJ, a repetition frequency of 1-20kHz, a focused spot size of 25-35μm, and a pulse width of 50-200ns. It employs a cold-processing laser mode, resulting in a small heat-affected zone. It only ablates specific points at a preset workstation, without damaging the surrounding casing or the battery itself.

[0041] 300 injection module Figure 6As shown, the entire system adopts existing technology. The liquid injection module 300 is equipped with an elastic liquid injection nozzle 310, which, together with the vacuum pumping and pressure replenishment system, can form a close-fitting surface seal with the microchannel inlet, isolating external water vapor and air, and ensuring the cleanliness of the replenished liquid; through gradient pressure control, it avoids the mixing of air bubbles.

[0042] The sealing and repair module uses a double-layer composite sealing coating 400, which includes a base sealing layer 410 and a reinforcing sealing layer 420. The base sealing layer 410 is a polyurethane-urea material doped with nano-silica, with a thickness of 40-50μm, strong adhesion, and can completely fill the tiny gaps in the microchannel. The reinforced sealing layer 420 is made of fluorine-modified polyurethane with a thickness of 30-40μm. It is resistant to electrolyte corrosion, high and low temperature aging, and has excellent long-term sealing stability.

[0043] The vision positioning system accurately identifies the preset opening station, enabling precise alignment of the laser, liquid injection, and sealing stations; the central controller automatically completes the linkage control of the entire process of opening, liquid injection, and sealing, realizing automated operation.

[0044] The complete fluid resuscitation process is as follows: Laser-controlled aperture: A laser is emitted at a fixed point to penetrate and break through the thin wall at the bottom of the blind hole 131 layer by layer, forming a microchannel that connects to the inside of the battery. Sealed docking and electrolyte injection: The elastic injection nozzle 310 fits into the microchannel inlet, first vacuuming and degassing, then segmented low-pressure wetting, constant flow injection, and pressure stabilization to complete electrolyte replenishment; In-situ sealing repair: After the fluid replenishment is completed, the sealing coating 400 is applied layer by layer through the sealing repair module to seal the microchannels and restore the overall sealing performance of the battery; Recycling: After subsequent electrolyte loss, the above process can be repeated to achieve multiple non-destructive electrolyte replenishment.

[0045] Examples and comparative examples: The following examples and comparative examples use 72Ah-280Ah square lithium-ion and sodium-ion power batteries as verification objects to conduct performance tests: Example 1 The composite shell structure 100 has a total thickness of 2.0±0.05mm, the light-transmitting outer layer 110 has a thickness of 1.0±0.02mm, the light-absorbing intermediate layer 120 has a thickness of 0.3mm, and the metal inner layer 130 has a thickness of 0.7mm; the blind hole 131 has a diameter of 80±3μm and a cone angle of 85±3°; the laser wavelength is 1064nm and the single pulse energy is 10±0.5mJ; and a double-layer sealing coating is used in conjunction.

[0046] Example 2

[0047] Adapted for sodium-ion batteries, the composite shell structure has a total thickness of 1.8±0.05mm, and the blind hole cone angle and thin wall thickness are adjusted to ensure system compatibility.

[0048] Example 3

[0049] The high-capacity energy storage battery is adapted to the structure, with a thickened composite shell structure of 100mm overall thickness and a widened micro-pillar array spacing to meet high-power operating conditions.

[0050] Comparative Example 1

[0051] The hexagonal close-packed solid micropillar array was eliminated, and the light-absorbing intermediate layer 120 was a flat single-layer structure.

[0052] Comparative Example 2

[0053] It uses a single layer of sealant for sealing, without a double-layer composite protective structure.

[0054] The performance was evaluated based on the sealing leakage rate, maximum number of repeated replenishment cycles, and capacity retention rate after replenishment, according to national standards. The results of the performance tests and analysis are as follows: Each embodiment can stably achieve more than 800 cycles of reuse, the sealing leakage rate meets the high sealing level requirements of power batteries, and the capacity recovery rate after replenishment is excellent. Comparative Example 1 is prone to pore blockage and thermal deformation, resulting in a significant decrease in the number of times it can be reused. Comparative Example 2 is prone to swelling and cracking with long-term use, and has a high risk of sealing failure.

[0055] Test results demonstrate that the three-layer composite structure, array arrangement design, and double-layer sealing system of this invention synergistically achieve the core advantages of non-destructive opening, multiple reuse, and long-term sealing, with stable and reliable technical effects.

[0056] The technical solution of this invention can be extended to the electrolyte replenishment scenarios of solid-state batteries and semi-solid-state batteries. It only requires adaptation and adjustment of the electrolyte system and sealing materials, and has a wide range of applications.

[0057] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A composite shell structure for non-destructive electrolyte replenishment of power batteries, characterized in that, The composite shell structure (100) is integrated on the battery shell (500) of the power battery, forming a sealed part of the battery shell (500); the composite shell structure (100) is provided with a light-transmitting outer layer (110), a light-absorbing intermediate layer (120) and a metal inner layer (130) stacked sequentially from the outside to the inside, and the inner side of the metal inner layer (130) faces the internal cavity of the power battery; The inner metal layer (130) has a blind hole (131) with the opening of the blind hole (131) facing the light-absorbing intermediate layer (120), and the bottom of the blind hole (131) has a thin-walled structure (132).

2. The composite shell structure for non-destructive electrolyte replenishment of power batteries according to claim 1, characterized in that, The light-absorbing intermediate layer (120) is a hexagonal close-packed solid micro-pillar array structure, and the solid micro-pillars are arranged in a continuous manner along the stacking direction of the three-layer structure; the blind hole (131) is an inverted cone shape, and the blind hole (131) is coaxially arranged with the corresponding single solid micro-pillar in the light-absorbing intermediate layer (120) to form a preset opening position that can be penetrated by laser.

3. The composite shell structure for non-destructive electrolyte replenishment of power batteries according to claim 2, characterized in that, The light-transmitting outer layer (110) is made of light-transmitting insulating ceramic material with a thickness of 0.8-1.2 mm, a light transmittance of 90-95% for 1064 nm wavelength laser, and a bending strength of 350-400 MPa.

4. The composite shell structure for non-destructive electrolyte replenishment of power batteries according to claim 2, characterized in that, The light-absorbing intermediate layer (120) is made of polyimide composite carbon black-graphene material with a thickness of 0.2-0.4 mm, a porosity of 30±5%, an absorption rate of 93-97% for 1064 nm wavelength laser, and a single-point ablation threshold of 5 mJ / cm². The solid micropillar array has a micropillar diameter of 80-120 μm, a center-to-center array spacing of 250-350 μm between adjacent micropillars, and the height of the micropillars is consistent with the thickness of the light-absorbing intermediate layer (120).

5. The composite shell structure for non-destructive electrolyte replenishment of power batteries according to claim 2, characterized in that, The inner metal layer (130) is made of aluminum alloy sheet with a thickness of 0.5-0.7mm.

6. The composite shell structure for non-destructive electrolyte replenishment of power batteries according to claim 2, characterized in that, The blind hole (131) has a diameter of 70-90μm, a depth of 300±10μm, a cone angle of 80-88°, and a thickness of 40-60μm at the bottom of the blind hole (131) that does not penetrate the thin wall.

7. A refillable power battery, comprising a battery casing (500) and battery cells, characterized in that, The battery housing (500) is integrated with a composite housing structure (100) for non-destructive fluid replenishment of a power battery as described in any one of claims 1-6.

8. A laser-induced microchannel non-destructive fluid replenishment system for power batteries, characterized in that, The composite shell structure (100) for non-destructive fluid replenishment of power batteries as described in any one of claims 1-6, the pulsed fiber laser processing module (200), the fluid injection module (300), and the sealing and repair module; The pulsed fiber laser processing module (200) is disposed on the outside of the light-transmitting outer layer (110) of the composite shell structure (100), and is used to emit laser to penetrate the light-transmitting outer layer (110), ablate the light-absorbing intermediate layer (120) and break through the thin-walled structure (132) of the blind hole (131) of the metal inner layer (130), forming a microchannel connecting the inside of the power battery; The electrolyte injection module (300) is used to seal and dock with the inlet of the microchannel and inject electrolyte into the power battery in a quantitative manner; The sealing and repair module is used to apply a sealing coating (400) to the entrance of the microchannel after the liquid injection is completed to achieve gas-tight sealing.

9. The laser-induced microchannel non-destructive fluid replenishment system for power batteries according to claim 8, characterized in that, The pulsed fiber laser processing module (200) uses a three-cascaded fiber laser with a laser wavelength of 1060-1070nm, a single pulse energy of 5-15mJ, a repetition frequency of 1-20kHz, a focused spot diameter of 25-35μm, and a pulse width of 50-200ns.

10. The laser-induced microchannel non-destructive fluid replenishment system for power batteries according to claim 8, characterized in that, The sealing coating (400) has a double-layer composite structure, which includes a basic sealing layer (410) and a reinforcing sealing layer (420) from the inside out. The basic sealing layer (410) is made of polyurethane-urea material doped with nano-SiO2 particles, with a thickness of 40-50 μm and a nano-SiO2 doping amount of 1-3 wt%. The reinforced sealing layer 420 is made of fluorine-modified polyurethane with a fluorine content of 8-12 wt% and a thickness of 30-40 μm.

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