Semi-solid-state lithium battery diaphragm integrated with sensing function and preparation method of semi-solid-state lithium battery diaphragm

Abstract

The invention relates to a semi-solid lithium battery diaphragm integrated with a sensing function and a preparation method thereof, the diaphragm is composed of a polymer matrix, lithium salts, a nano filler and at least one micro sensor, the polymer matrix comprises PEO, PAN, PVDF, PVA, PMMA and the like, the lithium salts comprise LiTFSI, LiPF6, LiBF4 and LiFSI, and the nano filler comprises graphene oxide, SiO2, MWCNTs, ZnO, Al2O3 and the like. The integration of the microsensor enables the diaphragm to provide critical battery state information, thereby enhancing the performance of the battery management system. The preparation method of the diaphragm comprises a solvent casting method, a melt mixing method and the like, and post-treatment steps such as drying and cutting.

Description

Technical Field

[0001] The present invention relates to the technical field of semi-solid lithium batteries, in particular to a semi-solid lithium battery diaphragm with integrated sensing function and a preparation method thereof. Background Art

[0002] With the popularity of electric vehicles and wearable devices, the demand for high-safety and high-performance lithium batteries is increasing. Existing lithium battery technology faces the dual challenges of safety and performance, especially the stability problem under extreme conditions. Semi-solid electrolytes have gradually solved the above problems because they combine the high safety of solid electrolytes and the high ion conductivity of liquid electrolytes.

[0003] However, existing semi-solid electrolytes still have the defect of making it difficult to monitor the battery status in real time, which in turn limits their applications in safety and performance optimization. Summary of the invention

[0004] The purpose of the present invention is to develop a semi-solid lithium battery separator with integrated sensing function and a preparation method thereof to solve the limitations in the prior art.

[0005] The present invention integrates a micro sensor in a semi-solid electrolyte to achieve real-time monitoring of the battery state, thereby improving the safety and performance of the battery.

[0006] The present invention provides a polymer-based gel electrolyte, in which a micro sensor is embedded through a chemical synthesis method. The micro sensor monitors the temperature, pressure and electrochemical state inside the battery, and provides real-time data for the battery management system, thereby optimizing battery performance and preventing potential safety problems.

[0007] The present invention selects polymer materials with high ion conductivity and good mechanical strength, and precisely controls the ratio of lithium salt and additives to prepare a semi-solid electrolyte that has excellent electrochemical properties and can be effectively embedded in the sensor. In addition, further optimization schemes enhance the mechanical properties and thermal stability of the diaphragm by adding nanofillers, such as graphene oxide.

[0008] The present invention also provides a preparation process of the diaphragm, which includes the steps of sensor integration, electrolyte material mixing, diaphragm molding and curing. The process can efficiently produce a semi-solid lithium battery diaphragm with integrated sensing function, and the obtained diaphragm has a uniform microstructure and excellent electrochemical properties.

[0009] The present invention provides a semi-solid lithium battery separator with integrated sensing function, characterized in that the separator comprises a polymer matrix, a lithium salt, a nanofiller and at least one micro sensor. The separator not only has excellent electrochemical performance and mechanical strength, but also can monitor key parameters of the battery in real time, such as temperature, pressure, humidity and electrochemical state.

[0010] The polymer matrix is ​​selected from at least one of poly(ethylene oxide) (PEO), polyacrylonitrile (PAN), poly(vinylidene fluoride) (PVDF), polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA).

[0011] The selection of lithium salt should focus on improving ion conductivity, preferably at least one of LiTFSI, LiPF6, LiBF4 and LiFSI.

[0012] The nanofiller is preferably at least one of graphene oxide, SiO2 nanoparticles, multi-walled carbon nanotubes (MWCNTs), zinc oxide (ZnO) and aluminum oxide (Al2O3) nanoparticles, which can further enhance the mechanical properties and electrochemical stability of the diaphragm.

[0013] Furthermore, the micro sensor is at least one of a temperature sensor, a pressure sensor, an electrochemical sensor, a humidity sensor and a current sensor. The diaphragm can respectively monitor the temperature, pressure, humidity and electrochemical state of the battery in real time during use.

[0014] Among them, the ion conductivity of the membrane is higher than 1×10 -3 S / cm, and the separator has a tensile strength better than 5 MPa.

[0015] The above-mentioned membrane can be prepared by solvent casting, melt mixing, phase inversion, double roll calendaring or spraying technology to ensure that the micro sensor can be effectively placed in the membrane.

[0016] The present invention also provides a battery, characterized in that the battery comprises the above-mentioned semi-solid lithium battery separator with integrated sensing function. The battery can be used in electric vehicles, wearable devices, aerospace equipment, medical equipment or large energy storage systems.

[0017] As a further preferred embodiment, the diaphragm further comprises a flame retardant additive, and the flame retardant additive is selected from magnesium hydroxide (Mg(OH)2).

[0018] Further preferably, the thickness of the diaphragm is between 10 microns and 500 microns.

[0019] The preparation process of the diaphragm further includes post-processing, and the post-processing process is selected from at least one of drying, cutting and surface treatment.

[0020] The present invention also provides a method for preparing a semi-solid lithium battery separator with integrated sensing function, comprising the following steps: selecting a polymer matrix, a lithium salt, a nanofiller and at least one microsensor; mixing the polymer matrix, lithium salt and nanofiller to form a mixture; distributing the microsensor in the mixture; and molding and curing the mixture by solvent casting, melt mixing, phase inversion, double-roll calendering or spraying technology to prepare a separator.

[0021] The polymer matrix, lithium salt and nanofiller are selected based on their electrochemical properties, mechanical strength and compatibility.

[0022] The distribution of the micro sensors is based on specific locations of temperature, pressure, humidity and electrochemical state that need to be monitored during battery use.

[0023] The method further comprises one or more post-processing steps, wherein the post-processing steps are selected from at least one of drying, cutting and surface treatment to meet the specification requirements of the final application.

[0024] The present invention is based on the ion conduction mechanism inside the semi-solid electrolyte and the electrochemical reaction monitoring of the sensor. In the electrolyte, lithium ions migrate through the gaps between polymer chains and the channels provided by the nanofillers, thereby achieving efficient ion conduction. At the same time, the embedded microsensor can monitor the temperature, pressure and electrochemical state of the battery in real time. These data are analyzed by the battery management system to optimize the battery's charging and discharging strategy and improve the battery's performance and safety.

[0025] The key to the preparation of the diaphragm is: (1) Mix the selected polymer, lithium salt and nanofiller in a specific ratio and prepare a uniform mixture by solvent or melt mixing. (2) Distribute the microsensor in the mixture according to the designed position and direction, and then control the pressure and temperature to shape and solidify the mixture in a mold to form a semi-solid electrolyte diaphragm with integrated sensing function. (3) Post-process the diaphragm, such as drying and cutting. DETAILED DESCRIPTION

[0026] Example 1

[0027] Poly(ethylene oxide) (PEO) was used as a polymer, LiTFSI as a lithium salt, and a small amount of graphene oxide was added as a nanofiller. The micro temperature sensor was evenly distributed in the mixture. The separator was prepared by solvent casting and dried at 60°C for 24 hours.

[0028] Example 2

[0029] Polyacrylonitrile (PAN) is used as the base polymer, LiPF6 as the lithium salt, and SiO2 nanoparticles as the filler. The integrated sensor is a pressure sensor designed to monitor pressure changes inside the battery. The mixture is prepared by melt mixing and molded in a hot press at a temperature of 150°C and a pressure of 5MPa, and finally cooled naturally at room temperature to form a diaphragm with pressure sensing function.

[0030] Example 3

[0031] Polyvinylidene fluoride (PVDF) was used as the polymer matrix, LiBF4 as the lithium salt, and multi-walled carbon nanotubes (MWCNTs) were added as the conductive filler. The integrated sensor is an electrochemical sensor for monitoring the electrochemical state of the battery. The diaphragm was prepared by the phase inversion method and vacuum dried at 80°C for 12 hours.

[0032] Example 4

[0033] The hybrid polymer system of PEO and PAN is combined, the mixed lithium salt of LiTFSI and LiPF6, and zinc oxide (ZnO) nanoparticles are used as fillers. The integrated sensor is an electrochemical sensor for monitoring the changes in the electrolyte interface during the battery charge and discharge cycle. The separator is prepared by double-roll calendering and the separator is UV-cured at room temperature.

[0034] Example 5

[0035] A new polymer mixture including PEO and PVDF, LiFSI as lithium salt, and aluminum oxide (Al2O3) nanoparticles as filler are used. The integrated sensor is a dual-function temperature and humidity sensor to monitor the temperature and humidity changes of the battery working environment in real time. The diaphragm is prepared by wet spin coating technology and dried at 70°C for 16 hours under vacuum.

[0036] Example 6

[0037] A mixed polymer of polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA) is used, LiBOB is used as a lithium salt, and nano-sized magnesium hydroxide (Mg(OH)2) is used as a flame retardant additive. The integrated sensor is a current sensor for detecting internal short circuits in the battery. The separator is prepared by spraying technology and hot-pressed and cured at 100°C.

[0038] Comparative Example 1

[0039] A traditional liquid electrolyte lithium battery was selected, without any integrated sensors, and a standard polypropylene (PP) diaphragm was used.

[0040] The membranes of Examples 1-6 showed ion conductivity superior to that of the comparative example, among which the membrane of Example 3 showed the highest ion conductivity, reaching 1.5×10 -3 S / cm level, significantly improving the charge and discharge efficiency of the battery.

[0041] The separators of all the examples showed good mechanical strength, especially Example 5, which had a tensile strength of 5 MPa due to the addition of aluminum oxide (Al2O3) nanoparticles, much higher than the PP separator of the comparative example.

[0042] The integrated sensors in all embodiments can accurately monitor the temperature, pressure, humidity and electrochemical state of the battery, wherein the current sensor in Embodiment 6 can immediately detect anomalies at the early stage of a short circuit inside the battery.

[0043] Compared with the comparative example, the battery using the semi-solid lithium battery separator with integrated sensing function exhibits better cycle stability and longer service life. After 1000 charge and discharge cycles, the capacity retention rate of the battery of Example 4 is still over 80%, while that of the battery of the comparative example is only 60%.

[0044] The technical solution of the present invention can significantly improve the safety of lithium batteries by integrating sensors to monitor the battery status in real time, and can promptly detect and warn of potential safety hazards, such as overheating, overvoltage and other faults or accidents.

[0045] The semi-solid electrolyte membrane of the present invention has excellent ionic conductivity and mechanical strength, can support more efficient charging and discharging processes, and improve the energy density and cycle life of the battery. In addition, the data collected by the sensor can be used to optimize the battery management system and further improve battery performance.

[0046] The present invention is not only applicable to lithium batteries in electric vehicles and wearable devices, but can also be extended to various application fields such as energy storage systems and drones.

Claims

1. A semi-solid lithium battery separator with integrated sensing function, characterized in that: The separator comprises a polymer matrix, a lithium salt, a nanofiller and at least one microsensor.

2. The separator according to claim 1, wherein the polymer matrix is ​​selected from at least one of poly(ethylene oxide) (PEO), polyacrylonitrile (PAN), poly(vinylidene fluoride) (PVDF), polyvinyl alcohol (PVA) and polymethyl methacrylate (PMMA).

3. The separator according to claim 1, wherein the lithium salt is selected from at least one of LiTFSI, LiPF6, LiBF4 and LiFSI.

4. The separator according to claim 1, wherein the nanofiller is selected from at least one of graphene oxide, SiO2 nanoparticles, multi-walled carbon nanotubes (MWCNTs), zinc oxide (ZnO) and aluminum oxide (Al2O3) nanoparticles. 5 . The diaphragm according to claim 1 , wherein the micro sensor is at least one of a temperature sensor, a pressure sensor, an electrochemical sensor, a humidity sensor, and a current sensor.

6. The diaphragm according to claim 1, characterized in that The diaphragm is prepared by solvent casting, melt mixing, phase inversion, double-roll calendering or spraying technology.

7. The diaphragm according to claim 1, characterized in that The separator further comprises a flame retardant additive selected from magnesium hydroxide (Mg(OH)2).

8. The diaphragm according to claim 1, characterized in that The thickness of the separator is between 10 micrometers and 500 micrometers.

9. A battery, characterized in that: The battery comprises the semi-solid lithium battery separator with integrated sensing function according to claim 1.

10. A method for preparing a semi-solid lithium battery separator with integrated sensing function, comprising the following steps: Select a polymer matrix, a lithium salt, a nanofiller and at least one microsensor; mix the polymer matrix, the lithium salt and the nanofiller to form a mixture; distribute the microsensor in the mixture; and shape and solidify the mixture by solvent casting, melt mixing, phase inversion, double-roll calendering or spraying technology to prepare a diaphragm.