CN-121977720-A - Lithium battery embedded FBG temperature sensor and preparation method and application thereof

CN121977720ACN 121977720 ACN121977720 ACN 121977720ACN-121977720-A

Abstract

The invention belongs to the technical field of battery temperature detection, and particularly discloses an implantable FBG temperature sensor in a lithium battery, and a preparation method and application thereof. The embedded FBG temperature sensor in the lithium battery comprises a single-mode fiber with an FBG, a capillary quartz tube and an adhesive, wherein the adhesive is arranged at two ends of the capillary quartz tube and used for fixing the single-mode fiber with the FBG, the single-mode fiber with the FBG is arranged in the capillary quartz tube under the action of the adhesive and is ensured not to be in contact with the capillary quartz tube, and the capillary quartz tube is internally provided with inert atmosphere. According to the invention, through the original packaging structure with fixed two ends and suspended middle, a mechanical stress shielding cabin is constructed, the structural design directly cuts off the transmission path of mechanical stress to the sensing grating at the physical level, and a pure temperature signal only related to heat accumulation can be obtained without relying on complex algorithm compensation, so that the measurement accuracy is remarkably improved.

Inventors

LUO HAO
LU MI
GUO CHENG
LIU WENFENG
LI CONG
WANG HONGXIN

Assignees

厦门理工学院

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (7)

1. The lithium battery embedded FBG temperature sensor is characterized by comprising a single-mode fiber with FBG, a capillary quartz tube and an adhesive; The adhesive is arranged at two ends of the capillary quartz tube and is used for fixing a single-mode fiber with FBG; The single-mode fiber with the FBG is arranged in the capillary quartz tube under the action of the adhesive, and is ensured not to be in contact with the capillary quartz tube; The capillary quartz tube is internally provided with an inert atmosphere.
2. The lithium battery embedded FBG temperature sensor according to claim 1, wherein the center wavelength of the FBG in the single-mode fiber with the FBG is 1545-1555 nm, and the length of the grid area is 5-10 mm; the FBG in the single-mode fiber with the FBG is positioned at the center of the capillary quartz tube in the length direction.
3. The lithium battery embedded FBG temperature sensor according to claim 1 or 2, wherein the diameter of the single-mode fiber with the FBG is 120-130 μm, and the length is greater than the length of the grating region of the FBG; the inner diameter of the capillary quartz tube is 150-250 mu m, the outer diameter is 300-400 mu m, and the length is longer than the length of the grating region of the FBG.
4. An implantable FBG temperature sensor in a lithium battery according to claim 3, characterized in that the adhesive comprises an epoxy glue.
5. The method for manufacturing the lithium battery embedded FBG temperature sensor according to any one of claims 1 to 4, which is characterized by comprising the following steps: 1) Preparing FBG on the single-mode fiber to obtain the single-mode fiber with FBG; 2) And (3) arranging adhesives at two ends of the capillary quartz tube, and fixing the single-mode fiber with the FBG by using the adhesives, so that the single-mode fiber with the FBG is not contacted with the capillary quartz tube, and the implanted FBG temperature sensor in the lithium battery is obtained.
6. The application of the lithium battery internal implanted FBG temperature sensor prepared by the preparation method of claim 5 in lithium battery internal temperature detection.
7. Use of an implantable FBG temperature sensor in a lithium battery according to claim 6 for internal temperature detection of a lithium battery, characterized in that the detection method comprises the steps of: S1, implanting an implanted FBG temperature sensor in a lithium ion battery between positive and negative electrode plates of the battery in a lamination or winding process of the lithium ion battery, and using a high-temperature-resistant adhesive tape for auxiliary positioning, wherein an aluminum plastic film or a shell of the battery is led out from one end, far away from the FBG, of a single-mode fiber with the FBG; S2, connecting one end of a single-mode fiber with an FBG (fiber Bragg grating) of the battery aluminum-plastic film or the shell to an optical fiber demodulator, inverting the temperature change in the battery by detecting the drift amount of the central wavelength of the FBG, and realizing the temperature detection in the lithium battery; The capillary quartz tube bears the expansion force and stacking pressure of the pole pieces in the lithium battery, so that the FBG in the lithium battery only responds to temperature change, and the passive decoupling of temperature and mechanical stress is realized.

Description

Lithium battery embedded FBG temperature sensor and preparation method and application thereof Technical Field The invention relates to the technical field of battery temperature detection, in particular to an implantable FBG temperature sensor in a lithium battery, and a preparation method and application thereof. Background In the field of safety monitoring and thermal behavior research of lithium ion batteries, accurate acquisition of internal temperature of the battery is a key basis for evaluating heat accumulation, performance degradation and thermal runaway risks. The traditional battery surface temperature measurement (such as attaching a thermocouple) often has obvious hysteresis due to the thermal resistance of battery packaging materials (such as aluminum plastic films and steel shells), and cannot truly reflect the thermal state inside a battery core (particularly in the center of a winding core). Especially in the research of high-rate charge and discharge and safety failure mechanism, the internal heat generation rate is far greater than the surface heat dissipation rate, and the internal temperature can be 10 ℃ or more higher than the surface. The fiber Bragg grating (FiberBraggGrating, FBG) is considered to be the most suitable temperature sensor implanted into the lithium ion battery because of the advantages of small size, strong electromagnetic interference (EMI) resistance, good corrosion resistance, essential insulation and the like. However, FBG sensing technology faces a core physical challenge in battery internal applications, cross-sensitivity issues. The center reflection wavelength shift (Δλb) of the fiber grating is affected by both temperature change (Δt) and strain (Δε), and the relationship is typically expressed as: where Pe is the effective elasto-optical coefficient of the fiber, α is the coefficient of thermal expansion, and ζ is the coefficient of thermo-optical. Inside lithium ion batteries, the environment is extremely complex. As the battery is charged and discharged, the positive and negative electrode plates undergo lithium intercalation and deintercalation reactions, resulting in changes in the lattice volume of the electrode plates (e.g., the graphite negative electrode expands by about 10% when intercalating lithium, and the silicon-based negative electrode is larger), which macroscopically represents the periodic expansion and contraction (i.e., "respiration effect") of the battery cell. In addition, to ensure the energy density and cycle life of the battery, the battery typically exerts a significant preload force (StackingPressure) during assembly. If a bare fiber FBG is directly implanted into a cell, the FBG will be subjected to both temperature variations inside the cell and significant mechanical compressive/tensile stresses. During the charging process, the pole pieces expand to squeeze the fiber, creating axial and radial strain, resulting in non-thermally induced wavelength drift. The existing data show that the temperature measurement error caused by the stress can reach 5-15 ℃, and the judgment of the real thermal state of the battery is seriously interfered. In the prior art (such as chinese patent application CN115628826 a), although a double-layer package structure of a quartz tube and a metal tube is used to protect the optical fiber, a metal material (GH 3030 alloy) is introduced, which is absolutely contraindicated in the battery because the metal conductor punctures the separator to cause the internal short circuit of the battery, causing a catastrophic effect. In addition, the diameter of the structure in the prior art reaches more than 1mm, so that the flatness of the battery pole piece is seriously damaged, and lithium precipitation and local inactivation can be caused. There is also a scheme (for example, chinese patent application CN117477050 a) that sets a plurality of sets of fiber grating sensors to perform algorithm decoupling on stress. The method has the advantages that the double optical fibers can cause certain performance influence on the battery due to the volume problem during the internal implantation, meanwhile, due to different stress values of each place on the level sheet, the double optical fibers can have position deviation during placement, and according to the optical fiber principle, the different decoupling temperatures of the stress are different, so that uncontrollable errors exist in the subsequent algorithm decoupling. Based on this, how to provide an all-insulated, ultra-miniature, passive stress-decoupled lithium battery embedded FBG temperature sensor is a challenge in the art. Disclosure of Invention In view of the above, the invention provides an implantable FBG temperature sensor in a lithium battery, and a preparation method and application thereof, which solve a plurality of defects (including the damage to the flatness of a battery pole piece, the lithium precipitation and local inactivation, the influence