CN113972413A - Solid-state battery capable of monitoring electrolyte temperature in real time and temperature monitoring method - Google Patents

Abstract

The invention discloses a solid-state battery capable of monitoring the temperature of an electrolyte in real time and a temperature monitoring method; the solid-state battery includes: a positive electrode, a negative electrode, a solid electrolyte and a temperature monitoring device; wherein, the temperature monitoring device includes: a single mode fiber and at least one FBG sensor; each FBG sensor is connected in the single-mode optical fiber at intervals in series; the single-mode optical fiber is partially embedded in the solid electrolyte between the positive electrode and the negative electrode, and at least one FBG sensor is connected in series with the embedded part. The invention can realize the rapid and in-situ measurement of multiple parameters of the internal temperature, the pressure and the strain of the solid-state battery.

Description

Solid-state battery capable of real-time monitoring of electrolyte temperature and temperature monitoring method

technical field

The invention belongs to the technical field of solid-state batteries, and in particular relates to a solid-state battery capable of monitoring electrolyte temperature in real time and a temperature monitoring method.

Background technique

Rechargeable batteries are a common reusable energy storage device today. Since the size of the battery can be freely made, it can be used in a variety of devices, such as electric vehicles, smartphones, laptops, mobile tablets, watches, and hybrid electric vehicles. Rechargeable batteries are used in various devices. The increasing use of rechargeable batteries has put battery life and reliability to the test.

Due to their high energy density, long cycle life, and low self-discharge capability, solid-state batteries have become a suitable choice for supplying electrical energy to various devices. However, accidents caused by battery quality such as self-explosion of mobile phone batteries and spontaneous combustion of batteries occur frequently, which have a serious impact on the life and property safety of the general public. The reason why these accidents occur is that in the current application scenarios of solid-state batteries, only the electrical performance output from the solid-state battery is concerned, but the thermal performance inside the solid-state battery is not concerned. However, the internal thermal performance of the battery is the indicator that can best reflect the performance and safety status of the solid-state battery; therefore, only real-time monitoring of the internal thermal performance of the solid-state battery is the best solution to evaluate the battery performance and prevent battery safety accidents. way.

Currently, only in precision electronic devices, temperature sensors are placed around solid-state batteries to monitor the thermal performance of solid-state batteries by monitoring the ambient temperature of the solid-state batteries. However, it takes a certain amount of time for the heat energy to be conducted from the interior of the solid-state battery to the external environment and then affect the ambient temperature. Therefore, this method of monitoring the ambient temperature of the battery cannot obtain the changes in parameters such as temperature, pressure and strain inside the battery in real time; therefore, how to There is no practical solution in the prior art to realize fast, in-situ measurement of multiple parameters of internal temperature, pressure and strain of solid-state batteries.

SUMMARY OF THE INVENTION

In order to solve the above technical problems existing in the prior art, the present invention provides a solid-state battery and a temperature monitoring method capable of monitoring the electrolyte temperature in real time.

The technical problem to be solved by the present invention is realized by the following technical solutions:

In a first aspect, the present invention provides a solid-state battery capable of monitoring electrolyte temperature in real time, including: a positive electrode, a negative electrode, and a solid-state electrolyte, and also includes: a temperature monitoring device; wherein,

The temperature monitoring device includes: a single-mode fiber and at least one FBG (Fiber Bragg Grating, fiber Bragg grating) sensor; each of the FBG sensors is serially connected in the single-mode fiber at intervals;

The single-mode optical fiber is partially embedded in the solid electrolyte between the positive electrode and the negative electrode, and at least one of the FBG sensors is connected in series with the embedded portion.

Preferably, the FBG sensor includes at least two;

Wherein, at least one of the FBG sensors is located in the solid electrolyte, and at least one of the FBG sensors is located outside the solid electrolyte.

Preferably, the distance between two adjacent FBG sensors is not less than the length of the FBG sensors.

Preferably, both the positive electrode and the negative electrode are lithium sheets.

Preferably, the part of the single-mode optical fiber embedded in the solid electrolyte is single-strand embedded.

Preferably, the portion of the single-mode optical fiber embedded in the solid electrolyte is embedded in a coil.

In a second aspect, the present invention provides a temperature monitoring method, which is applied to any of the above solid-state batteries that can monitor the electrolyte temperature in real time;

The method includes:

emitting light waves to the single-mode optical fiber embedded in the solid-state electrolyte of the solid-state battery through one port of the optical splitter;

At another port of the optical splitter, a fiber grating demodulation module is used to detect the wavelength and wavelength shift of the light waves reflected by each FBG sensor connected in series on the single-mode fiber;

Based on the detected wavelength and the amount of wavelength drift, the temperature at the location of each of the FBG sensors is calculated.

In the solid-state battery that can monitor the temperature of the electrolyte in real time, the single-mode optical fiber and the FBG sensor are embedded in the solid-state electrolyte; by monitoring the Bragg wavelength shift of the FBG sensor connected to the single-mode optical fiber, it is possible to obtain the information on the different positions inside the battery. The temperature and pressure changes and the temperature changes of the external environment of the battery, and the detected data have a high response speed and high detection accuracy. Based on the solid-state battery provided by the present invention, high-precision measurement of parameters such as temperature and pressure during battery operation can be realized, so as to monitor the thermal performance of the solid-state battery in the electronic equipment in real time, prevent the occurrence of catastrophic accidents, and realize the realization of the solid-state battery. Fast, in situ measurement of multiple parameters of internal temperature, pressure and strain.

Moreover, based on the solid-state battery provided by the present invention, it can also help to analyze the formation process of SEI (solid electrolyte interface, solid electrolyte interface) and evaluate the battery life, so that hidden faults can be discovered in advance in the battery design stage, and catastrophic accidents can also be avoided. Effect.

The present invention will be further described in detail below with reference to the accompanying drawings.

Description of drawings

1 is a schematic structural diagram of a solid-state battery capable of monitoring electrolyte temperature in real time according to an embodiment of the present invention;

Figure 2 is a schematic diagram of a single-mode optical fiber embedded in a solid electrolyte;

Fig. 3 is the physical map corresponding to Fig. 2;

Fig. 4 is another schematic diagram of embedding a single-mode optical fiber in a solid electrolyte;

Fig. 5 is the physical map corresponding to Fig. 4;

6 is a flowchart of a method for monitoring a pool provided by an embodiment of the present invention;

FIG. 7 is a diagram showing a connection relationship of devices in the method shown in FIG. 6 .

Detailed ways

The present invention will be described in further detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

In order to realize fast, in-situ measurement of the multi-parameters of the internal temperature, pressure and strain of the solid-state battery, the inventors of the present invention have tried a solution using a thermal resistance device. The thermal resistance devices mentioned here include thermistors and resistance temperature detectors.

Among them, the thermistor can be placed on the surface, terminal or close to the battery. A resistance temperature detector (RTD) is a device containing a metallic conductor whose resistance increases with temperature. The principle of RTD monitoring temperature is similar to that of thermistor. After applying a small current, and then measuring the voltage drop, the voltage can be converted into temperature. However, thermistor and resistance temperature detector can only be used for local surface or local internal temperature measurement of the battery; for internal measurement, the best measurement scheme should not affect the service life and performance of the battery, and should be resistant to battery materials. chemical environment and suitable for compatibility with battery assembly processes. Neither thermistors nor resistive temperature detectors can detect temperature gradients and possible hot spots on or elsewhere within the battery, and the monitored temperature deviates from the maximum temperature.

Considering the above factors and the current status of deposition and preparation technology, the inventors tried to use FBG fiber optic sensors for in-situ real-time monitoring of temperature and pressure in all-solid-state batteries, and proposed a solid-state battery that can monitor the electrolyte temperature in real time. Rapid, in situ measurement of multiple parameters of internal temperature, pressure and strain in solid-state batteries. Referring to FIG. 1 , the solid-state battery includes: a positive electrode, a negative electrode, a solid-state electrolyte, and a temperature monitoring device.

The temperature monitoring device comprises: a single-mode optical fiber and at least one FBG sensor; each FBG sensor is serially connected in the single-mode optical fiber; the single-mode optical fiber is partially embedded in the solid electrolyte between the positive electrode and the negative electrode, and the embedded part is at least in series A FBG sensor is connected.

Wherein, the distance between two adjacent FBG sensors is not less than the length of the FBG sensors.

Understandably, the FBG provides gratings along the length of the fiber to control the behavior of light. Bragg gratings are permanently changed by applying UV light and then embedded in the core of an optical fiber. These Bragg gratings act as wavelength-selective mirrors, and as the spectrum travels through the core, specific wavelengths are reflected back, leaving the rest of the spectrum almost unaffected.

In the embodiment of the present invention, the sensor in the single-mode fiber acts as a reflector of a specific wavelength, and the wavelength of the reflected light wave is expressed as λ _B =2n _eff Λ; where λ _B is the Bragg wavelength, and n _eff is the effective refractive index of the grating , Λ is the Bragg grating period.

In practical applications, the wavelength shift of the reflection peak _Δλ can be monitored, which is caused by changes in n _eff and Λ, both of which depend on local temperature, pressure and strain (ε) changes in the FBG sensor around environment of. When the Bragg reflection wavelength shifts, it is affected by temperature. The measurement of this wavelength shift is the basis of fiber grating sensors; for temperature changes, a change in Bragg wavelength can be observed, which is mainly due to temperature-dependent changes in refractive index, while thermal expansion has very little effect, and the grating spacing can be can be ignored.

Another advantage of embodiments of the present invention is that FBG sensors can be multiplexed, which means that multiple fiber gratings can be interconnected into a single fiber, enabling measurements at different locations along the length of the fiber. Furthermore, the Bragg wavelength varies linearly with temperature.

By comparing the capacity retention of the all-solid-state battery with and without the fiber optic sensor implantation for 100 cycles, it can be determined that the responses under the two conditions are almost the same, indicating that the implantation of the FBG sensor into the solid-state battery does not affect the electrochemical performance of the battery.

To sum up, in the embodiment of the present invention, the temperature and pressure changes at different positions inside the battery and the temperature changes of the battery external environment can be obtained by monitoring the Bragg wavelength shift of the FBG sensor connected to the single-mode fiber, and the data all have high response. The speed and detection accuracy are also relatively high. Based on the solid-state battery provided by the embodiments of the present invention, high-precision measurement of parameters such as temperature and pressure during battery operation can be achieved, so as to monitor the thermal performance of the solid-state battery in electronic equipment in real time, prevent catastrophic accidents, and realize the Rapid, in situ measurement of multiple parameters of internal temperature, pressure and strain in solid-state batteries.

Moreover, based on the solid-state battery provided by the embodiment of the present invention, it can also help to analyze the formation process of SEI (solid electrolyte interface, solid electrolyte interface) and evaluate the battery life, so that hidden faults can be discovered in advance in the battery design stage, and disasters can also be avoided. effects of sexual accidents.

Preferably, in the embodiment of the present invention, both the positive electrode and the negative electrode are lithium sheets. Solid-state electrolytes can employ common polymers such as polyvinylidene fluoride (PVDF-HFP) and lithium salts lithium bistrifluoromethanesulfonimide (C ₂ F ₆ LiNO ₄ S ₂ ). Using lithium sheets as positive and negative electrodes can achieve the effect of collecting a large number of lithium positive ions; under the action of chemical potential, the positive ions lose electrons, and the electrons flow to the negative electrode from the external circuit; the lithium ions that lose electrons are dissociated to the negative electrode through the solid electrolyte. ; The role of the lithium sheet as a solid negative electrode is to intercalate a large number of lithium ions that have lost electrons, and the positive ions of these negative ions that have lost electrons are freed from the positive electrode after the negative electrode is combined with the electrons; the role of the solid electrolyte is to make lithium ions in The conduction between the positive and negative electrodes is smooth. To put it simply, solid-state lithium batteries only rely on the movement of lithium ions between the positive and negative electrodes to achieve the charging and discharging process.

It is understandable that, compared with liquid lithium-ion batteries, all-solid-state batteries have the following advantages: first, the solid-state electrolyte is less flammable; second, without liquid electrolyte, the voltage platform can be made higher, which is conducive to further improving the specific energy of the battery; Third, the solid electrolyte can use lithium metal as the negative electrode. Due to the high hardness of the solid electrolyte, it is relatively difficult for lithium dendrites to penetrate the electrolyte, so the growth of dendrites can be inhibited to a certain extent; Fourth, the specific energy of lithium metal batteries significantly higher than that of lithium-ion batteries.

In one embodiment, at least two FBG sensors can be connected in series on the single-mode fiber, one inside the solid electrolyte and one outside the solid electrolyte. It can be understood that the FBG sensor inside the solid-state electrolyte is used to monitor the temperature and pressure inside the solid-state electrolyte, and the FBG sensor outside the solid-state electrolyte is mainly used to monitor the ambient temperature of the solid-state battery, so as to facilitate the temperature measurement inside and outside the solid-state battery. Compared.

In practical applications, as shown in FIG. 2 , the part of the single-mode optical fiber embedded in the solid electrolyte may be single-strand embedded. Figure 3 shows a physical view of the solid-state battery in this embedded way.

It can be understood that the solid-state battery shown in Figures 2 and 3 is more suitable for small-volume solid-state batteries, which can comprehensively detect the temperature inside the electrolyte with only a few FBG sensors.

In another implementation, as shown in FIG. 4 , the portion of the single-mode optical fiber embedded in the solid electrolyte may be embedded in a coil. Figure 5 shows a physical view of the solid-state battery in this embedded manner.

It can be understood that the solid-state battery shown in Figures 4 and 5 is more suitable for large-volume solid-state batteries; this is because a large number of FBG sensors can be connected in series on the single-mode optical fiber embedded in the solid-state electrolyte in a roll, and When embedded in a roll, the single-mode optical fiber and its series-connected FBG sensor can be coiled inside the solid electrolyte from top to bottom, so as to monitor the interior of the solid electrolyte in all directions.

Based on the solid-state battery that can monitor the temperature of the electrolyte in real time provided by the embodiment of the present invention, the embodiment of the present invention also provides a monitoring method for the battery, as shown in FIG. 6 and FIG. 7 , the method includes the following steps:

S10: Send light waves to a single-mode fiber in a solid-state battery through one port of the optical splitter.

Here, broadband light waves can be launched into a single-mode fiber.

S20: At the other port of the optical splitter, use a fiber grating demodulation module to detect the wavelength and wavelength shift of the light waves reflected by each FBG sensor connected in series on the single-mode fiber.

It can be understood that for precision equipment that needs to monitor the temperature of the electrolyte inside the solid-state battery, a fiber grating demodulation module can be integrated inside the device. The working principle of the fiber grating demodulation module can be found in the existing fiber grating demodulation module. instrument.

For ordinary equipment, it is only necessary to add a temperature monitoring device inside the solid-state battery during the research and development stage, and use the existing fiber grating demodulator to monitor the electrolyte temperature in real time, thereby assisting the design of the solid-state battery; when the solid-state battery design is finalized, The solid-state battery in the common equipment may not need to set the temperature monitoring device, and further need not integrate the fiber grating demodulation module.

In practical applications, a solid-state battery needs to be prepared in advance to achieve temperature monitoring; exemplarily, acetone and DMF (N,N-dimethylformamide) can be used as solvents, put into PVDF-HFP and stirred to dissolve; after that, put lithium The salt is stirred to fully dissolve to obtain an electrolyte solution; then, the electrolyte solution is encapsulated with plexiglass or silicone grease, and electrodes are placed; then, a single-mode optical fiber connected in series with the FBG sensor is placed between the electrolyte solution between the positive and negative electrodes , waiting for the solidification of the electrolyte solution to form a solid electrolyte to obtain a solid-state battery that can monitor the temperature of the electrolyte in real time.

S30: Calculate the temperature at the location of each FBG sensor based on the detected wavelength and the wavelength drift.

It can be understood that since the light waves of different wavelengths can be regarded as independent of each other, multiplexing transmission of multiple optical signals can be realized in one optical fiber. Two-way transmission can be achieved by arranging the signals in the two directions to be transmitted at different wavelengths. Depending on the wavelength division multiplexer, the number of wavelengths that can be multiplexed is also different, ranging from 2 to dozens of wavelengths. Generally, 8-wavelength and 16-wavelength systems are commercially available, depending on the allowable optical carrier wavelength interval. size.

Specifically, in the embodiment of the present invention, a plurality of FBG sensors are connected in series on an optical fiber, and the broadband light wave emitted by the broadband light source will pass through all the gratings through the splitter. The fiber grating demodulation module is coupled into the fiber grating demodulation module through the other port of the splitter; the fiber grating demodulation module is used to detect the wavelength of the light wave reflected by the FBG sensor arranged at each position and its wavelength shift relative to the central wavelength of the initial state, So as to demodulate the data; after corresponding data processing, the actual temperature of the environment where each grating is located can be calculated.

It should be noted that the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined as "first", "second" may expressly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example Or features are included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

Although the application is described herein in conjunction with the various embodiments, those skilled in the art will understand and understand from a review of the drawings, the disclosure, and the appended claims in practicing the claimed application. Other variations of the disclosed embodiments are implemented.

The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deductions or substitutions can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (7)

1. A solid-state battery that can monitor electrolyte temperature in real time, comprising: a positive electrode, a negative electrode, and a solid electrolyte, further comprising: a temperature monitoring device; wherein,

the temperature monitoring device includes: a single mode fiber and at least one FBG sensor; each FBG sensor is connected in the single-mode optical fiber at intervals in series;

the single-mode optical fiber is partially embedded in the solid electrolyte between the positive electrode and the negative electrode, and at least one FBG sensor is connected in series with the embedded part.

2. The solid-state battery according to claim 1, wherein the FBG sensors include at least 2;

wherein at least one of the FBG sensors is located in the solid electrolyte and at least one of the FBG sensors is located outside the solid electrolyte.

3. The solid-state battery according to claim 1, wherein a distance between adjacent two of the FBG sensors is not less than a length of the FBG sensors.

4. The solid-state battery according to claim 1, wherein the positive electrode and the negative electrode are both lithium sheets.

5. The solid-state battery according to claim 1, wherein the portion of the single-mode optical fiber embedded in the solid-state electrolyte is single-strand embedded.

6. The solid-state battery according to claim 1, wherein the portion of the single-mode optical fiber embedded in the solid-state electrolyte is embedded in a roll.

7. A temperature monitoring method applied to the solid-state battery according to any one of claims 1 to 6;

the method comprises the following steps:

emitting light waves to a single-mode optical fiber embedded in a solid electrolyte of the solid-state battery through one port of an optical splitter;

at the other port of the optical splitter, detecting the wavelength and the wavelength drift amount of the light wave reflected by each FBG sensor connected in series on the single-mode fiber by using a fiber bragg grating demodulation module;

and calculating the temperature of the position of each FBG sensor based on the detected wavelength and the wavelength drift amount.

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