Lithium battery thermal runaway early warning protection system based on PTC (Positive Temperature Coefficient) characteristics and manufacturing equipment

Abstract

The invention belongs to the technical field of lithium battery safety protection, particularly relates to a lithium battery thermal runaway early warning protection system based on PTC (Positive Temperature Coefficient) characteristics and manufacturing equipment, and aims to solve the problems that the temperature of each battery cell is difficult to monitor in real time, the sensitivity of battery runaway optimal temperature early warning and intervention intervals is relatively low and local thermal runaway cannot be inhibited in time in the prior art. According to the scheme, the lithium battery temperature sensor comprises a sensor which is made of a carbon-based PTC conductive polymer, a carrying strip is silver paste, a PI film is coated outside the carrying strip, a high and low temperature resistant double faced adhesive tape is coated on a single face, the thickness is 0.2 mm-0. 5mm, and the lithium battery temperature sensor is suitable for being installed on the surface or inside a lithium battery to sense the temperature and change of the battery; by adopting the PTC sheet-shaped sensor, the temperature and the change rate of the outer surface of the battery can be monitored in real time, and timely intervention can be performed at the early stage of prediction of out-of-control. Each battery cell can be monitored at the same time, accurate judgment can be made at the first time, and effective measures such as liquid cooling, fire fighting or fire fighting liquid injection are taken.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery safety protection, and particularly to a lithium battery thermal runaway early warning protection system and manufacturing equipment based on PTC characteristics. Background Art

[0002] Due to its advantages such as high energy density and long cycle life, lithium batteries are widely used in fields such as electric vehicles, energy storage systems, and consumer electronics. However, lithium batteries are prone to thermal runaway under abnormal conditions such as overcharging, over-discharging, short-circuiting, or high temperature, resulting in fire or explosion, posing serious safety hazards.

[0003] Traditional NTC (negative temperature coefficient) sampling sensors are generally arranged in small quantities and scattered in a battery pack, and their form is generally point sampling, which cannot monitor the temperature of each part of the battery cell and is even more difficult to monitor the temperature of each battery cell. At the same time, due to its relatively linear temperature-internal resistance curve, its sensitivity to the optimal temperature warning and intervention interval (60°C - 80°C) for battery runaway is relatively low. Therefore, when an abnormality occurs locally in a certain battery cell, it is difficult to detect it in time. By the time the abnormal temperature is detected at the temperature measurement point, the protection measures are already difficult to control the thermal diffusion.

[0004] In view of the above problems, the present invention document proposes a lithium battery thermal runaway early warning protection system and manufacturing equipment based on PTC characteristics. Through the resistance-temperature characteristics of the sheet-shaped PTC element, the temperature change of the entire surface of the lithium battery is monitored in real time. In the optimal temperature warning and intervention interval of the lithium battery, abnormal temperature rise is detected in time and the protection mechanism is triggered to ensure that the local thermal runaway of the lithium battery system can be suppressed in time and prevent greater accidents from occurring. Summary of the Invention

[0005] The purpose of the present invention is to solve the disadvantages of the existing technology, such as the difficulty in real-time monitoring of the temperature of each battery cell, relatively low sensitivity in the optimal temperature warning and intervention interval for battery runaway, and the inability to suppress local thermal runaway in time. A lithium battery thermal runaway early warning protection system and manufacturing equipment based on PTC characteristics are proposed.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A lithium battery thermal runaway early warning protection system based on PTC characteristics, comprising: a sensor made of a carbon-based PTC conductive polymer, with a carrier strip being a special silver paste, coated with a PI film on the outside, and laminated with a high and low temperature resistant double-sided adhesive on one side, with a thickness of 0.2 mm - 0.5 mm, suitable for being installed on the surface or inside of the lithium battery to sense the battery temperature and its changes;

[0008] A signal acquisition circuit configured to obtain the resistance value of the PTC element and convert it into a voltage signal;

[0009] A microcontroller (MCU), integrated in a battery management system (BMS), is configured to read the voltage signal, calculate the current temperature according to a mathematical model established based on the resistance-temperature characteristic curve of the PTC element, and implement the judgment and protection logic for abnormal temperature rise. Among them, a temperature threshold and a temperature change rate threshold are set. When the temperature or the temperature change rate exceeds the set threshold, corresponding protection measures are executed.

[0010] In a possible design, the signal acquisition circuit is further configured to convert the resistance change of the PTC element linearly or non-linearly into a corresponding voltage signal for the microcontroller (MCU) to perform accurate temperature calculation.

[0011] In a possible design, the protection measures include: when the calculated temperature value exceeds the set warning threshold, an alarm signal is issued and the liquid cooling system is controlled to be turned on to reduce the battery temperature; when the calculated temperature value exceeds the set danger threshold, the battery power supply is cut off to prevent thermal runaway; and when the temperature continues to rise and the temperature change rate exceeds the set threshold, fire extinguishing liquid is injected to quickly suppress thermal runaway.

[0012] In a possible design, the sensor has the characteristics of being thin, light, soft, so that it can be closely attached to the surface of the lithium battery or embedded inside it, thereby accurately and real-time sensing the temperature and changes of the battery, and improving the accuracy and reliability of early warning protection.

[0013] A manufacturing device for preparing the special silver paste in the above-mentioned lithium battery thermal runaway early warning protection system based on PTC characteristics, including a water bath cylinder. Inside the water bath cylinder, a reaction kettle is rotatably connected through a rotating bearing. Inside the reaction kettle, a stirring shaft is rotatably connected through a rotating bearing. A driving structure for stirring and centrifuging the raw materials is provided between the water bath cylinder and the reaction kettle. The driving structure includes an L-shaped plate fixedly welded on the top of the water bath cylinder;

[0014] The driving structure further includes a separation structure for separating the nano-silver precipitate and the supernatant in the reaction kettle after centrifugation, facilitating the subsequent washing of the sodium dodecylbenzenesulfonate contained in the nano-silver precipitate in the reaction kettle with deionized water to ensure the purity of the nano-silver precipitate. The separation structure includes a first drain pipe sealingly and slidably penetrating through the bottom of the reaction kettle, and the top end of the first drain pipe extends into the stirring shaft;

[0015] It further includes a drying oven arranged below the water bath cylinder. One side of the drying oven is fixedly penetrated with a feed pipe for injecting the nano-silver precipitate washed from the reaction kettle into the drying oven. A drying structure is arranged inside the drying oven for drying the nano-silver precipitate in the drying oven. The bottom of the reaction kettle is fixedly communicated with a second drain pipe.

[0016] In a possible design, the driving structure further includes a driving motor fixed to the top of the L-shaped plate. A first bevel gear is fixed to the output shaft of the driving motor. The top end of the stirring shaft sequentially rotates through the top inner wall of the reaction kettle and the L-shaped plate. A second bevel gear meshing with the first bevel gear is fixedly sleeved on the outer wall of the top of the stirring shaft. The cooperation of the driving motor, the first bevel gear and the second bevel gear is used to drive the stirring shaft to stir the raw materials in the reaction kettle. The bottom of the L-shaped plate is fixedly welded with a first mounting ring through a connecting rod. An electromagnet is fixed to the bottom of the first mounting ring. Both the first mounting ring and the electromagnet are sleeved on the outer wall of the stirring shaft. A first gear is slidably connected to the outer wall of the stirring shaft through a chute and a slider. A magnetic attraction force is generated between the first gear and the electromagnet to control the lifting of the first gear. An internal gear ring is fixed to the top of the reaction kettle, and the internal gear ring meshes with the first gear. When the first gear descends and meshes with the internal gear ring, it is used to make the stirring shaft drive the reaction kettle to rotate for centrifugal operation. When the first gear moves up and separates from the internal gear ring, the rotation of the stirring shaft is used to stir the raw materials in the reaction kettle. First feeding hoppers and second feeding hoppers are respectively fixedly communicated with both sides of the top of the reaction kettle; when stirring a variety of raw materials, the driving motor is used to drive the first bevel gear to rotate. The cooperation of the first bevel gear and the second bevel gear drives the stirring shaft to rotate to stir and mix the raw materials. And the water in the water bath cylinder is heated by the first heating sheet (the water temperature is 60 °C), and then the reaction kettle reacts under the water bath; after the reaction is completed, centrifugal treatment is carried out. The electromagnet is powered off to release the magnetic attraction force on the first gear. The first gear moves down into the internal gear ring and meshes with the internal gear ring. The stirring shaft can drive the reaction kettle to rotate to perform centrifugal operation on the mixture in the reaction kettle (where the centrifugal operation is 8000 rpm and centrifugation is carried out for 5 minutes). After centrifugation, nano-silver precipitate and supernatant are formed.

[0017] In a possible design, the separation structure further includes a fixing plate fixed to the outer wall of the first drain pipe. The fixing plate is located below the reaction kettle. A plurality of tension springs are fixed between the top of the fixing plate and the bottom of the reaction kettle. A plurality of drain ports are provided on the outer wall of the stirring shaft, and all the drain ports are located inside the reaction kettle. The top end of the first drain pipe extends into the stirring shaft and closes the drain ports. The cooperation between the first drain pipe and the drain ports can remove supernatants with different thicknesses. A fixing ring is fixed inside the stirring shaft above the first drain pipe. A piston rod is hermetically and slidably connected inside the stirring shaft, and the bottom end of the piston rod hermetically and slidably penetrates through the fixing ring. The bottom end of the piston rod is fixedly connected to the top end of the first drain pipe. The top end of the stirring shaft is rotationally communicated with a three-way valve. A water pump is fixed to one side of the water bath cylinder through a frame. The liquid inlet end of the water pump is communicated with the water bath cylinder through a pipeline. The liquid outlet end of the water pump is fixedly communicated with one of the liquid inlet ends of the three-way valve through a hose, for injecting clear water into the stirring shaft to drive the piston rod and the first drain pipe to move downward to remove supernatants with different thicknesses. A liquid return pipe is fixedly communicated with one side of the water bath cylinder. The top end of the liquid return pipe is fixedly communicated with the other liquid inlet end of the three-way valve. An electromagnetic valve is provided on the outer wall of the liquid return pipe. When the electromagnetic valve is opened, under the action of the tension spring, the water in the stirring shaft is re-injected into the water bath cylinder to control the reset of the first drain pipe, facilitating the separation function to be carried out again later; the glass windows in the water bath cylinder and the reaction kettle are aligned. Through the glass window, the position of the supernatant in the reaction kettle and the position of the top end of the first drain pipe located inside the stirring shaft can be observed. Then, the water in the water bath cylinder is injected into the three-way valve through the water pump and then injected into the stirring shaft through the three-way valve, and the water is above the piston rod. As the water volume increases, the piston rod and the first drain pipe are pushed downward, and the tension spring starts to stretch. When the first drain pipe drops to the intersection of the supernatant and the silver nanowire precipitate, the water pump stops operating. When the first drain pipe moves downward, the supernatant in the reaction kettle enters the stirring shaft through the drain port and is discharged to the outside through the first drain pipe. At this time, the removal operation of the supernatant can be completed; after the supernatant is discharged, the electromagnetic valve is opened, and the first drain pipe moves upward and resets under the action of the tension spring. The piston rod re-injects the water in the stirring shaft into the water bath cylinder through the three-way valve and the liquid return pipe.

[0018] In a possible design, the drying structure includes a fixed retaining ring fixed inside the drying box. A conical filter screen is slidably connected inside the drying box above the fixed retaining ring. The fixed retaining ring is used to limit the downward movement of the conical filter screen, and also facilitates the up and down movement of the conical filter screen later. One end of the drying box away from the feed pipe is fixed with a third drain pipe for discharging the moisture inside the drying box to facilitate later drying. A plurality of second heating sheets are fixed on the inner wall of the drying box for heating the temperature inside the drying box to dry the silver nanowire precipitate on the conical filter screen. A vacuum pump is fixed on one side of the drying box. The intake end of the vacuum pump extends into the drying box through a pipe for evacuating the drying box to a vacuum, which not only facilitates later drying but also prevents the silver nanowire precipitate from oxidizing with air during drying. An L-shaped dial plate is hermetically and slidably penetrated through one side of the drying box close to the feed pipe, and the L-shaped dial plate extends into the drying box and is located below the conical filter screen. An arc-shaped plate is fixed on the side of the L-shaped dial plate away from the drying box. The arc-shaped plate cooperates with the second drain pipe. When the second drain pipe rotates, it drives the L-shaped dial plate to move into the drying box by squeezing the arc-shaped plate. The L-shaped dial plate cooperates with the bottom inclined surface of the conical filter screen to drive the conical filter screen to move upward. After the L-shaped dial plate resets, the conical filter screen automatically moves downward. The conical filter screen can move up and down reciprocally, thereby jolting the silver nanowire, which not only facilitates the separation of moisture inside the silver nanowire but also accelerates the drying of the silver nanowire. A substrate is fixed at the top of one side of the L-shaped dial plate. The substrate is located on one side of the drying box. A fixed rod is fixed on one side of the drying box and slidably penetrates through the substrate. A first spring is fixed between the substrate and the drying box. The first spring is sleeved on the outer wall of the fixed rod for driving the L-shaped dial plate to move outward and reset, facilitating the L-shaped dial plate to be extended into the drying box again by the extrusion of the second drain pipe to drive the conical filter screen to move upward later;

[0019] It also includes an ultrasonic oscillator arranged below the drying box, which is used to perform organic coating on the dried nano-silver precipitate in the drying box, so that the surfactant is adsorbed on the surface of the silver powder to form a hydrophobic protective layer. The bottom of the conical filter screen is fixedly penetrated with a discharge pipe, and the bottom end of the discharge pipe extends through to the lower part of the drying box for injecting the nano-silver precipitate into the ultrasonic oscillator to facilitate the subsequent organic coating of the nano-silver precipitate. After the washing is completed, the second drain pipe rotates above the feed pipe, the valve on the second drain pipe is opened, and the nano-silver precipitate and deionized water in the reaction kettle are discharged onto the conical filter screen. The conical filter screen is used to separate the nano-silver precipitate and deionized water, and the deionized water is discharged through the third drain pipe. Then, the valves on the feed pipe and the third drain pipe are closed, the drying box is evacuated by a vacuum pump, and the second heating element is started to heat the temperature in the drying box to complete the drying operation of the nano-silver precipitate to obtain silver powder. The reaction kettle drives the second drain pipe to rotate. The second drain pipe touches the arc-shaped plate and pushes the L-shaped baffle to move towards the drying box. The first spring is compressed. When the L-shaped baffle touches the bottom inclined surface of the conical filter screen, it can drive the conical filter screen to move upward. After the L-shaped baffle loses the extrusion of the second drain pipe, it resets under the action of the first spring, and the conical filter screen moves downward synchronously to reset. Thus, the conical filter screen can move up and down to jolt the silver powder on it, which not only accelerates the solid-liquid separation on the conical filter screen but also improves the drying efficiency of the silver powder.

[0020] In a possible design, a plurality of first heating elements are fixedly arranged on the bottom inner wall of the water bath cylinder for heating the water in the water bath cylinder, so that the raw materials of the reaction kettle react in a water bath environment. A support ring is fixedly welded on the bottom inner wall of the water bath cylinder, and the top end of the support ring is hermetically and rotationally connected to the bottom of the reaction kettle. Both the second drain pipe and the first drain pipe penetrate through the support ring. Windows are fixedly embedded on one side of both the water bath cylinder and the reaction kettle, which is convenient for observing the intersection of the nano-silver precipitate and the supernatant in the reaction kettle. The stirring shaft is made of transparent tempered glass, which is convenient for observing the position of the first drain pipe through the window to complete the subsequent supernatant removal operation.

[0021] In a possible design, a closing plate for closing the bottom end of the second charging hopper is slidably connected to the inner wall of the top of the reactor. A plurality of second springs are fixed to the side of the closing plate away from the stirring shaft. One end of each of the plurality of second springs is fixed to the same fixing seat, and the fixing seat is fixedly welded to the inner wall of the top of the reactor. One end of the closing plate close to the stirring shaft is fixed with a first magnet by bolts. A liquid leakage port is provided in the closing plate. The liquid leakage port cooperates with the second charging hopper to drip sodium carbonate in the second charging hopper into the reactor, so as to adjust the pH value of the solution in the reactor. A second magnet located in the reactor is fixed to the outer wall of the stirring shaft by bolts. A repulsive force is generated between the second magnet and the first magnet to drive the closing plate to move outward, so that the liquid leakage port is aligned with the liquid outlet end of the second charging hopper. A second mounting ring is fixed to the inner wall of one side of the reactor. A rotating column is rotatably connected in the second mounting ring. The top end of the rotating column is fixed with a conical platform. The conical platform is located below the second charging hopper and is used to disperse the solution dripping from the second charging hopper to different positions in the reactor, so as to avoid local over-alkalinity of the solution inside the reactor. The bottom end of the rotating column is fixed with a second gear. One side of the closing plate is fixed with a U-shaped plate by bolts. One end of the U-shaped plate is fixed with a rack by bolts. The rack is engaged with the second gear. The closing plate drives the rack to move under the cooperation of the second magnet and the first magnet. The cooperation between the rack and the second gear drives the conical platform to rotate, and the solution dripping from the second charging hopper is thrown to different positions in the reactor. A glass electrode sensor is fixedly penetrated through one side of the reactor to detect the pH value of the solution in the reactor; when adding sodium carbonate solution into the reactor through the second charging hopper to adjust the pH value of the solution in the reactor, the stirring shaft drives the second magnet to rotate. When the second magnet is aligned with the first magnet, the repulsive force between the first magnet and the second magnet pushes the closing plate and the rack to move, the liquid leakage port is aligned with the second charging hopper, the solution in the second charging hopper drips onto the conical platform through the liquid leakage port, and the rack drives the conical platform to rotate through the second gear, and the dripping solution is thrown to different positions in the reactor, so that the sodium carbonate solution is uniformly injected into the reactor, and local over-alkalinity of the solution inside the reactor is avoided.

[0022] Beneficial effects: The present invention adopts a developed PTC sheet sensor with high sensitivity at 60 °C to 80 °C, which can monitor the temperature and change rate of the outer surface of the battery in real time and intervene in time at the initial stage of predicting out-of-control;

[0023] The sheet-shaped PTC element adopted in the present invention has a simple structure, few sampling points, and is easy to be integrated into the existing lithium battery protection circuit. Due to its physical characteristics, it has high reliability and is suitable for large-scale popularization and application in the lithium battery industry;

[0024] In the present invention, the PTC sheet sensor has high sensitivity and a sheet structure that is easy to arrange, can monitor each battery cell simultaneously, and thus can make a relatively accurate judgment in the first time. Through effective measures such as liquid cooling, fire fighting, or injecting fire extinguishing liquid, the temperature of the abnormal battery cell can be quickly reduced to a safe value in a timely manner, preventing the development of thermal runaway.

[0025] In the present invention, to improve the stability and printing suitability of the silver paste, the silver powder is subjected to surface electroless silver plating and organic coating by this manufacturing equipment, greatly improving the high conductivity and adhesiveness of the silver paste in the later stage, ensuring that the PTC sheet sensor can stably adhere to the lithium battery, and ensuring the stability of the silver paste and the sensor material in the lithium battery electrolyte environment, guaranteeing the stability of the PTC sheet sensor monitoring. Brief Description of the Drawings

[0026] Figure 1 It is a three-dimensional structure schematic diagram of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0027] Figure 2 It is a sectional structure schematic diagram of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0028] Figure 3 It is a three-dimensional sectional structure schematic diagram of the water bath cylinder and the stirring shaft of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0029] Figure 4 It is a three-dimensional exploded structure schematic diagram of the first mounting ring, the internal gear ring, and the internal gear ring of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0030] Figure 5 It is a three-dimensional exploded structure schematic diagram of the water bath cylinder and the reaction kettle of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0031] Figure 6 It is a sectional structure schematic diagram of the stirring shaft of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0032] Figure 7 It is a three-dimensional sectional structure schematic diagram of the drying oven and the conical filter screen of the manufacturing equipment provided in Embodiment 1 of the present invention;

[0033] Figure 8 It is a three-dimensional sectional structure schematic diagram of the reaction kettle of the manufacturing equipment provided in Embodiment 2 of the present invention;

[0034] Figure 9 It is a three-dimensional exploded structure schematic diagram of the closing plate, the conical table, the second gear, and the stirring shaft of the manufacturing equipment provided in Embodiment 2 of the present invention.

[0035] In the figure: 1, water bath cylinder; 2, reaction kettle; 3, support ring; 4, stirring shaft; 5, first charging hopper; 6, second charging hopper; 7, L-shaped plate; 8, driving motor; 9, first bevel gear; 10, first mounting ring; 11, electromagnet; 12, first gear; 13, internal gear ring; 14, three-way valve; 15, water pump; 16, solenoid valve; 17, return liquid pipe; 18, second bevel gear; 19, piston rod; 20, fixed ring; 21, first drain pipe; 22, fixed plate; 23, tension spring; 24, drain port; 25, first heating sheet; 26, second drain pipe; 27, drying oven; 28, feed pipe; 29, fixed retaining ring; 30, conical filter screen; 31, L-shaped deflector; 32, arc-shaped plate; 33, base plate; 34, fixed rod; 35, first spring; 36, second heating sheet; 37, vacuum pump; 38, third drain pipe; 39, discharge pipe; 40, glass electrode sensor; 41, fixed seat; 42, closing plate; 43, second spring; 44, liquid leakage port; 45, first magnet; 46, second magnet; 47, U-shaped plate; 48, second mounting ring; 49, conical platform; 50, rotating column; 51, second gear; 52, rack; 53, glass window; 54, ultrasonic oscillator. Specific implementation mode

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0037] Embodiment 1: A lithium battery thermal runaway early warning protection system based on PTC characteristics, which mainly consists of a sensor, a signal acquisition circuit, and a microcontroller MCU integrated in a battery management system (BMS).

[0038] Sensor part: The sensor uses a carbon-based PTC conductive polymer as the core material, and its carrier strip is made of special silver paste to ensure the conductivity. The sensor is coated with a PI film to enhance its insulation and corrosion resistance. A high and low temperature resistant double-sided adhesive is laminated on one side of the sensor, so that the sensor can be firmly attached to the surface of the lithium battery or embedded inside it. The thickness of the sensor is controlled at 0.3 mm, ensuring its thin, light, and flexible characteristics, so that it can closely fit the battery and accurately and real-time sense the temperature of the battery and its changes.

[0039] Signal acquisition circuit part: The signal acquisition circuit is responsible for obtaining the resistance value of the sensor (i.e., the PTC element). Since the resistance value of the PTC element changes with temperature, the signal acquisition circuit can linearly or non-linearly convert this resistance change into a corresponding voltage signal. The converted voltage signal has high precision and stability, providing a reliable basis for subsequent temperature calculation.

[0040] Microcontroller MCU part: The microcontroller MCU is integrated in the battery management system (BMS) and is responsible for reading the voltage signal output by the signal acquisition circuit. A mathematical model based on the resistance-temperature characteristic curve of the PTC element is pre-stored inside the MCU. Through this model, the MCU can calculate the current temperature value of the battery. At the same time, the MCU is also set with a temperature threshold and a temperature change rate threshold. When the calculated temperature value or temperature change rate exceeds the set threshold, the MCU will execute corresponding protection measures.

[0041] Specific protection measures include: When the calculated temperature value exceeds the set warning threshold, the MCU will issue an alarm signal to remind the operator to pay attention to the change in battery temperature, and at the same time control the opening of the liquid cooling system to reduce the battery temperature and prevent the temperature from rising further.

[0042] When the calculated temperature value exceeds the set danger threshold, the MCU will cut off the battery power supply to prevent thermal runaway and ensure the safety of the battery.

[0043] When the temperature continues to rise and the temperature change rate exceeds the set threshold, the MCU will inject fire extinguishing liquid to quickly suppress thermal runaway and prevent serious consequences such as fire.

[0044] Through the above specific implementation methods, the lithium battery thermal runaway early warning protection system based on PTC characteristics can accurately and real-time sense the temperature and changes of the battery, and execute corresponding protection measures according to the preset thresholds, thereby improving the safety, reliability and service life of lithium batteries.

[0045] Sensor design and working principle: The sensor is made of carbon-based PTC (positive temperature coefficient) conductive polymer material, which has unique resistance-temperature characteristics, that is, as the temperature increases, its resistance value will also increase accordingly.

[0046] The carrier strip of the sensor is made of special silver paste, which is coated with a PI (polyimide) film to provide good insulation and weather resistance. The single-sided composite high and low temperature resistant double-sided tape makes the sensor thin, light and flexible, and convenient to fit on the surface or inside of the lithium battery.

[0047] The sensor real-time senses the temperature and changes of the battery, and reflects the change of the battery temperature through the change of its resistance value.

[0048] System solution and signal processing: The signal acquisition circuit is responsible for obtaining the resistance value of the PTC element. Since the resistance of the PTC element changes with temperature, the temperature information of the battery can be indirectly obtained by measuring the resistance value.

[0049] The signal acquisition circuit converts the resistance change of the PTC element into a voltage signal. This conversion process is based on Ohm's law and circuit principles. Through precise circuit design, a linear relationship between the resistance change and the voltage signal can be ensured.

[0050] The microcontroller (MCU) in the BMS (Battery Management System) reads the voltage signal and calculates the actual temperature value through the built-in algorithm. The MCU is also responsible for implementing the judgment and protection logic for abnormal temperature rise.

[0051] Protection Logic and Response Mechanism

[0052] According to the resistance-temperature characteristic curve of the PTC element, a mathematical model is established. This model is used to describe the corresponding relationship between the resistance value and the temperature and is the basis for the system to judge abnormal temperature.

[0053] Set the temperature threshold and the temperature change rate threshold. For example, set 60°C as the warning threshold, 80°C as the danger threshold, and at the same time set the temperature change rate threshold as ΔT > 2°C / S.

[0054] The system monitors the temperature and temperature change rate of the battery in real time. When the temperature exceeds the warning threshold, an alarm signal is sent, and the liquid cooling system is started to reduce the battery temperature.

[0055] When the temperature exceeds the danger threshold, the system cuts off the battery power supply to prevent more serious consequences caused by thermal runaway.

[0056] If the temperature continues to rise and the temperature change rate exceeds the set threshold (ΔT > 2°C / S), the system will inject fire extinguishing liquid to quickly reduce the battery temperature and ensure safety.

[0057] Refer to Figure 1 and Figure 2 , a manufacturing device for preparing the special silver paste in the above-mentioned lithium battery thermal runaway early warning protection system based on PTC characteristics. The manufacturing device mainly includes a water bath cylinder 1, and a reaction kettle 2 rotatably connected through a rotating bearing is designed inside the water bath cylinder 1. A stirring shaft 4 is also rotatably connected inside the reaction kettle 2 through a rotating bearing for stirring the raw materials during the reaction process.

[0058] Refer to Figure 2 and Figure 3 , a plurality of first heating sheets 25 are installed on the bottom inner wall of the water bath cylinder 1. These heating sheets will heat the water in the water bath cylinder 1 after being powered on, thereby providing a constant water bath environment for the raw materials in the reaction kettle 2. A support ring 3 is fixedly welded on the bottom inner wall of the water bath cylinder 1, and the top of the support ring is hermetically and rotatably connected to the bottom of the reaction kettle 2. At the same time, the second drain pipe 26 and the first drain pipe 21 both penetrate through the support ring 3.

[0059] Refer toFigure 1 , Figure 2 and Figure 4 , in order to realize the stirring and centrifugation operations of raw materials, a driving structure is provided between the water bath cylinder 1 and the reaction kettle 2. The water bath cylinder 1 is made of 316L stainless steel with a wall thickness of 8 mm, and the inner surface is electrolytically polished with Ra ≤ 0.4 μm; the reaction kettle 2 is made of Hastelloy C276 with a volume of 50L - 100L and a design pressure of 0.6 MPa. This driving structure first includes an L-shaped plate 7 fixedly welded to the top of the water bath cylinder 1. At the top of the L-shaped plate 7, a driving motor 8 is installed, and its output shaft is connected to a first bevel gear 9. The top end of the stirring shaft 4 sequentially rotates through the top inner wall of the reaction kettle 2 and the L-shaped plate 7, and a second bevel gear 18 meshing with the first bevel gear 9 is fixedly sleeved on its top outer wall. In this way, the operation of the driving motor 8 will drive the stirring shaft 4 to rotate through the cooperation of the first bevel gear 9 and the second bevel gear 18, thereby completing the stirring of the raw materials in the reaction kettle 2. In addition, a first mounting ring 10 is fixedly welded to the bottom of the L-shaped plate 7 through a connecting rod, and an electromagnet 11 is installed at the bottom of the first mounting ring 10. They are jointly sleeved on the outer wall of the stirring shaft 4. A first gear 12 is slidably connected to the outer wall of the stirring shaft 4 through a chute and a slider. A magnetic attraction force can be generated between this first gear 12 and the electromagnet 11 to control the lifting of the first gear 12. An internal gear ring 13 is fixed to the top of the reaction kettle 2 and meshes with the first gear 12. When the first gear 12 descends and meshes with the internal gear ring 13, the rotation of the stirring shaft 4 will drive the reaction kettle 2 to rotate, thereby performing a centrifugation operation; and when the first gear 12 moves upward and separates from the internal gear ring 13, the rotation of the stirring shaft 4 is only used to stir the raw materials in the reaction kettle 2. First charging hoppers 5 and second charging hoppers 6 are respectively and fixedly communicated with both sides of the top of the reaction kettle 2 for adding various raw materials required for the reaction.

[0060] Specifically, first add various raw materials into the reaction kettle 2 through the first charging hopper 5 and the second charging hopper 6. Then start the driving motor 8, and drive the stirring shaft 4 to rotate through the cooperation of the first bevel gear 9 and the second bevel gear 18 to stir and mix the raw materials. At the same time, heat the water in the water bath cylinder 1 through the first heating sheet 25 (the water temperature is controlled at 60 °C) so that the reaction kettle 2 reacts under the water bath.

[0061] Specifically, after the reaction is completed, centrifugation is carried out. At this time, the electromagnet 11 is powered off, the magnetic attraction force on the first gear 12 is released, and the first gear 12 moves downward into the internal gear ring 13 and meshes with the internal gear ring 13. In this way, the rotation of the stirring shaft 4 can drive the reaction kettle 2 to rotate to perform a centrifugation operation on the mixture in the reaction kettle 2 (the centrifugation operation is 8000 rpm for 5 minutes). After centrifugation, nano-silver precipitate and supernatant are formed.

[0062] Refer to Figure 2 ,Figure 3 and Figure 5 After the reaction is completed, in order to separate the silver nanoparticles precipitate in the reaction kettle 2 from the supernatant after centrifugation, the device is designed with a separation structure. This separation structure includes a first drain pipe 21 that seals and slides through the bottom of the reaction kettle 2, and its top extends into the stirring shaft 4. A plurality of drain ports 24 are provided on the outer wall of the stirring shaft 4, all located within the reaction kettle 2. The top of the first drain pipe 21 can extend into the stirring shaft 4 and close the drain ports 24, so as to cooperate with the drain ports 24 to remove the supernatant with different thicknesses. Further, a fixing ring 20 is fixed within the stirring shaft 4 above the first drain pipe 21, and a piston rod 19 is also hermetically and slidably connected within the stirring shaft 4. The bottom end of the piston rod 19 hermetically slides through the fixing ring 20 and is fixedly connected to the top end of the first drain pipe 21. The top end of the stirring shaft 4 is rotationally connected to a three-way valve 14 for controlling the flow direction of the liquid. One side of the water bath cylinder 1 is fixed with a water pump 15 through a frame. The liquid inlet end of the water pump 15 is connected to the water bath cylinder 1 through a pipeline, and the liquid outlet end is fixedly connected to one of the liquid inlet ends of the three-way valve 14 through a hose for injecting clean water into the stirring shaft 4. In this way, when it is necessary to remove the supernatant, the water in the water bath cylinder 1 can be injected into the three-way valve 14 through the water pump 15 and then injected into the stirring shaft 4 through the three-way valve 14. As the amount of water increases, it will push the piston rod 19 and the first drain pipe 21 to move downward, so that the supernatant in the reaction kettle 2 enters the stirring shaft 4 through the drain ports 24 and is discharged to the outside through the first drain pipe 21. In addition, a fixing plate 22 is fixed on the outer wall of the first drain pipe 21, located below the reaction kettle 2. A plurality of tension springs 23 are fixed between the top of the fixing plate 22 and the bottom of the reaction kettle 2 to provide a pulling force when the first drain pipe 21 moves downward and help the first drain pipe 21 move upward and reset after the supernatant discharge is completed. One side of the water bath cylinder 1 is also fixedly connected to a return pipe 17, and the top end of the return pipe 17 is fixedly connected to the other liquid inlet end of the three-way valve 14. An electromagnetic valve 16 is provided on the outer wall of the return pipe 17. When the electromagnetic valve 16 is opened, under the action of the tension spring 23, the water in the stirring shaft 4 will be re-injected into the water bath cylinder 1 through the three-way valve 14 and the return pipe 17.

[0063] Specifically, then the water in the water bath cylinder 1 is injected into the three-way valve 14 through the water pump 15 and then injected into the stirring shaft 4 through the three-way valve 14. As the amount of water increases, it will push the piston rod 19 and the first drain pipe 21 to move downward, and the tension springs 23 start to stretch. When the first drain pipe 21 drops to the intersection of the supernatant and the silver nanoparticles precipitate, the water pump 15 stops operating. At this time, the supernatant in the reaction kettle 2 will enter the stirring shaft 4 through the drain ports 24 and be discharged to the outside through the first drain pipe 21, completing the operation of removing the supernatant.

[0064] Refer to Figure 4 and Figure 5, on one side of the water bath cylinder 1 and the reaction kettle 2, a glass window 53 is fixedly embedded, which is convenient for the operator to view the intersection of the nano-silver precipitate and the supernatant in the reaction kettle 2. In addition, the stirring shaft 4 is made of transparent tempered glass, which enables the operator to clearly view the position of the first drain pipe 21 through the glass window 53, so as to complete the subsequent supernatant removal operation.

[0065] Refer to Figure 1 , Figure 2 , Figure 3 and Figure 7 , the device also sets a drying oven 27 below the water bath cylinder 1, and a feed pipe 28 is fixedly penetrated through one side of it, which is used to inject the nano-silver precipitate washed in the reaction kettle 2 into the drying oven 27. A drying structure is designed in the drying oven 27 to dry the nano-silver precipitate. The bottom of the reaction kettle 2 is fixedly connected with a second drain pipe 26, which is used to discharge the waste water generated during the washing process.

[0066] Refer to Figure 7 , the drying structure includes firmly installing a fixed retaining ring 29 in the drying oven 27, and its position is determined and unchanged. Above the fixed retaining ring 29, a conical filter screen 30 is provided, and the filter screen is slidably connected with the drying oven 27 and can move up and down within a certain range. The existence of the fixed retaining ring 29 not only limits the downward movement distance of the conical filter screen 30, but also provides stable limit support for the subsequent up and down movement of the conical filter screen 30. One end of the drying oven 27 far from the feed pipe 28 is fixedly connected with a third drain pipe 38. This design helps to discharge the accumulated moisture inside the drying oven 27 in time, creating favorable conditions for the subsequent drying process. At the same time, a plurality of second heating sheets 36 are installed on the inner wall of the drying oven 27, and these heating sheets will increase the temperature inside the drying oven 27 after being powered on, so as to effectively dry the nano-silver precipitate on the conical filter screen 30. To further improve the drying effect, a vacuum pump 37 is also installed on one side of the drying oven 27. The vacuum pump 37 is a two-stage rotary vane pump (ultimate vacuum 1×10-2Pa, pumping speed 20L / min), and is equipped with a vacuum gauge (range 1×10 5～Monitor the vacuum degree in real time (1×10-3 Pa). The intake end of the vacuum pump 37 extends into the drying oven 27 through a pipeline, and can evacuate the inside of the drying oven 27 to a vacuum state when needed. This design not only helps to accelerate the drying process, but also effectively avoids the oxidation reaction of the silver nanoparticles with air during the drying process. On one side of the drying oven 27 close to the feed pipe 28, an L-shaped baffle 31 is hermetically slid through. One end of the L-shaped baffle 31 extends into the drying oven 27 and is located below the conical filter screen 30. The other end of the L-shaped baffle 31 is fixedly connected with an arc-shaped plate 32, and this arc-shaped plate 32 cooperates with the second drain pipe 26. When the second drain pipe 26 rotates, it drives the L-shaped baffle 31 to move into the drying oven 27 by squeezing the arc-shaped plate 32. The L-shaped baffle 31 cooperates with the bottom inclined surface of the conical filter screen 30 and can drive the conical filter screen 30 to move upward. When the L-shaped baffle 31 returns to its original position, the conical filter screen 30 will automatically move downward under the action of gravity. In this way, the conical filter screen 30 can move up and down reciprocally under the action of the L-shaped baffle 31, thereby jolting the silver nanoparticles. This design not only helps to separate the water inside the silver nanoparticles, but also accelerates the drying process of the silver nanoparticles. To ensure that the L-shaped baffle 31 can return to its original position smoothly, a base plate 33 is fixed to the top of one side of it. The base plate 33 is located on one side of the drying oven 27 and is connected to the drying oven 27 through a fixedly inserted sliding rod 34. At the same time, a first spring 35 is installed between the base plate 33 and the drying oven 27, and this spring is sleeved on the outer wall of the sliding rod 34. The function of the first spring 35 is to drive the L-shaped baffle 31 to move outward and return to its original position after being squeezed, so as to facilitate the L-shaped baffle 31 to extend into the drying oven 27 smoothly and drive the conical filter screen 30 to move upward when it is squeezed by the second drain pipe 26 again later.

[0067] Specifically, during the process of the reaction kettle 2 driving the second drain pipe 26 to rotate, when the second drain pipe 26 touches the arc-shaped plate 32, it will push the L-shaped baffle 31 to move towards the drying oven 27. At this time, the first spring 35 will be compressed. When the L-shaped baffle 31 touches the bottom inclined surface of the conical filter screen 30, it will drive the conical filter screen 30 to move upward. When the L-shaped baffle 31 loses the extrusion of the second drain pipe 26, it will return to its original position under the action of the first spring 35, and at the same time the conical filter screen 30 will also move downward and return to its original position synchronously. In this way, the conical filter screen 30 can move up and down under the action of the L-shaped baffle 31, thereby jolting the silver powder on it. This design not only helps to accelerate the solid-liquid separation process on the conical filter screen 30, but also further improves the drying efficiency of the silver powder.

[0068] Inside the water bath cylinder 1, there is a PT100 temperature sensor (model WZP-231) and a PID temperature control module (accuracy ±0.5°C). The first heating element 25 uses a silicon nitride ceramic heating plate (rated power 5 kW), and together with a circulating water pump (flow rate 10 L / min), it realizes a constant temperature control of ±0.3°C.

[0069] For the parts that need to be sealed, double mechanical seals can be used (material SiC / SiC, leakage rate < 1×10 - 6 Pa·m 3 / s).

[0070] Referring to Figure 1 、 Figure 2 and Figure 7 In addition, an ultrasonic oscillator 54 is also provided below the drying oven 27 of this manufacturing equipment. When the nano silver precipitate in the drying oven 27 is dried, it can be put into the ultrasonic oscillator 54 for organic coating treatment. During this process, the surfactant will adsorb on the surface of the silver powder to form a hydrophobic protective layer. To achieve this operation, a discharge pipe 39 is fixedly penetrated through the bottom of the conical filter 30. The bottom end of this discharge pipe extends through to the lower part of the drying oven 27, and is used to inject the dried nano silver precipitate into the ultrasonic oscillator 54 for organic coating treatment.

[0071] Specifically, after the washing is completed, the second drain pipe 26 will rotate above the feed pipe 28. At this time, by opening the valve on the second drain pipe 26, the nano silver precipitate and deionized water in the reaction kettle 2 can be discharged onto the conical filter 30 together. The conical filter 30 separates the nano silver precipitate and deionized water, and discharges the deionized water through the third drain pipe 38. Subsequently, the valves on the feed pipe 28 and the third drain pipe 38 are closed, and the drying oven 27 is evacuated by a vacuum pump 37. At the same time, the second heating element 36 is started to heat the temperature in the drying oven 27, thereby completing the drying operation of the nano silver precipitate and obtaining silver powder.

[0072] Example 2: Refer to Figure 9, on the basis of Embodiment 1, an improvement is made: a closing plate 42 is slidably connected to the inner wall of the top of the reaction kettle 2, and the closing plate 42 is used to close the bottom end of the second charging hopper 6. A plurality of second springs 43 are installed on the side of the closing plate 42 away from the stirring shaft 4, and one ends of these springs are jointly fixed on a fixing seat 41. The fixing seat 41 is fixedly welded to the inner wall of the top of the reaction kettle 2. One end of the closing plate 42 close to the stirring shaft 4 is fixed with a first magnet 45 by bolts, and a liquid leakage port 44 is also provided inside it. The liquid leakage port 44 cooperates with the second charging hopper 6 to drip the sodium carbonate solution in the second charging hopper 6 into the reaction kettle 2 to adjust the pH value of the solution. A second magnet 46 located inside the reaction kettle 2 is fixed to the outer wall of the stirring shaft 4 by bolts. When the second magnet 46 is aligned with the first magnet 45, a repulsive force will be generated between them to drive the closing plate 42 to move outward and align the liquid leakage port 44 with the liquid outlet end of the second charging hopper 6. A second mounting ring 48 is also fixed to one inner wall of the reaction kettle 2, and a rotating column 50 is rotatably connected inside the mounting ring. A conical platform 49 is fixed to the top end of the rotating column 50, and the conical platform 49 is located below the second charging hopper 6 and is used to disperse the solution dripping from the second charging hopper 6 at different positions in the reaction kettle 2 to avoid local over-alkalinity. A second gear 51 is fixed to the bottom end of the rotating column 50. One side of the closing plate 42 is fixed with a U-shaped plate 47 by bolts, and a rack 52 is fixed to one end of the U-shaped plate 47 by bolts. The rack 52 meshes with the second gear 51. When the closing plate 42 drives the rack 52 to move under the cooperation of the second magnet 46 and the first magnet 45, the rack 52 will drive the conical platform 49 to rotate through the second gear 51, so as to throw the solution dripping from the second charging hopper 6 to different positions in the reaction kettle 2. In addition, a glass electrode sensor 40 is also fixedly penetrated through one side of the reaction kettle 2, and the sensor is used to monitor the pH value of the solution in the reaction kettle 2 in real time.

[0073] Specifically, during the process of dripping the sodium carbonate solution into the reaction kettle 2 through the second charging hopper 6 to adjust the pH value of the solution, the stirring shaft 4 will drive the second magnet 46 to rotate. When the second magnet 46 is aligned with the first magnet 45, the repulsive force between them will push the closing plate 42 and the rack 52 to move together. At this time, the liquid leakage port 44 will be aligned with the second charging hopper 6, so that the solution in the second charging hopper 6 can drip onto the conical platform 49 through the liquid leakage port 44. At the same time, the rack 52 will drive the conical platform 49 to rotate through the second gear 51, so as to throw the dripping solution to different positions in the reaction kettle 2. In this way, it can be ensured that the sodium carbonate solution is uniformly injected into the reaction kettle 2 and effectively avoid the situation of local over-alkalinity of the solution inside the reaction kettle 2.

[0074] The usage method of the manufacturing equipment includes the following steps:

[0075] S1. To improve the stability and printing suitability of the silver paste, the silver powder needs to be surface-treated. First, electroless silver plating is carried out on the silver powder, and then organic coating is performed. Electroless silver plating: AgNO, sodium dodecylbenzenesulfonate (SDBS), and isoascorbic acid (C6H8O6) are injected into the reaction kettle 2 through the first hopper 5. Then, sodium carbonate (Na2CO3) is slowly dropped into the water bath cylinder 1 through the second hopper 6 to adjust the pH value of the mixed solution.

[0076] S2. When dropping sodium carbonate solution into the reaction kettle 2 through the second hopper 6 to adjust the pH value of the solution in the reaction kettle 2, the stirring shaft 4 drives the second magnet 46 to rotate. When the second magnet 46 aligns with the first magnet 45, the repulsive force between the first magnet 45 and the second magnet 46 pushes the closing plate 42 and the rack 52 to move. The liquid leakage port 44 aligns with the second hopper 6, and the solution in the second hopper 6 drops onto the conical platform 49 through the liquid leakage port 44. The rack 52 drives the conical platform 49 to rotate through the second gear 51, and the dropped solution is thrown to different positions in the reaction kettle 2, so that the sodium carbonate solution is evenly injected into the reaction kettle 2, avoiding local over-alkalinity of the solution inside the reaction kettle 2.

[0077] S3. When stirring a variety of raw materials, the driving motor 8 drives the first bevel gear 9 to rotate. The cooperation between the first bevel gear 9 and the second bevel gear 18 drives the stirring shaft 4 to rotate to stir and mix the raw materials. And the water temperature in the water bath cylinder 1 is heated to 60 °C by the first heating sheet 25. Then the reaction kettle 2 reacts under the water bath. After the reaction, centrifugation is carried out. The electromagnet 11 is powered off, and the magnetic attraction to the first gear 12 is released. The first gear 12 moves down into the internal gear ring 13 and meshes with the internal gear ring 13. The stirring shaft 4 can drive the reaction kettle 2 to rotate to perform centrifugation on the mixture in the reaction kettle 2 (where the centrifugation operation is 8000 rpm for 5 minutes). After centrifugation, nano-silver precipitation and supernatant are formed.

[0078] S4. After centrifugation, remove the supernatant. When removing the supernatant, align the glass window 53 in the water bath cylinder 1 with the glass window 53 in the reaction kettle 2. Through the glass window 53, the position of the supernatant in the reaction kettle 2 and the position of the top end of the first drain pipe 21 inside the stirring shaft 4 can be observed. Then, inject the water in the water bath cylinder 1 into the three-way valve 14 through the water pump 15, and inject it into the stirring shaft 4 through the three-way valve 14. And the water is above the piston rod 19. As the water volume increases, the piston rod 19 and the first drain pipe 21 are pushed downward, and the tension spring 23 starts to stretch. When the first drain pipe 21 drops to the intersection of the supernatant and the silver nanowire precipitate, the water pump 15 stops operating. And when the first drain pipe 21 moves downward, the supernatant in the reaction kettle 2 enters the stirring shaft 4 through the drain port 24 and is drained to the outside through the first drain pipe 21. At this time, the removal operation of the supernatant can be completed. After the supernatant is drained, open the solenoid valve 16, and the first drain pipe 21 moves upward and resets under the action of the tension spring 23. The piston rod 19 injects the water in the stirring shaft 4 back into the water bath cylinder 1 through the three-way valve 14 and the return pipe 17;

[0079] S5. Then, inject deionized water into the reaction kettle 2 through the first hopper 5. Through the stirring of the stirring shaft 4, the silver nanowire precipitate is mixed with the deionized water. The residual sodium dodecylbenzenesulfonate (SDBS) and unreacted ions are removed by the deionized water. Then, solid-liquid separation is carried out through step S3, and the silver nanowire precipitate is washed 3 times repeatedly. After the washing is completed, the second drain pipe 26 rotates to the upper side of the feed pipe 28. Open the valve on the second drain pipe 26, and drain the silver nanowire precipitate and deionized water in the reaction kettle 2 onto the conical filter screen 30. The conical filter screen 30 is used to separate the silver nanowire precipitate and the deionized water, and drain the deionized water through the third drain pipe 38. Then, close the valves on the feed pipe 28 and the third drain pipe 38. Vacuum the drying oven 27 through the vacuum pump 37, and the second heating element 36 starts to heat the temperature in the drying oven 27 to complete the drying operation of the silver nanowire precipitate and obtain silver powder;

[0080] S6. In addition, when the stirring shaft 4 drives the reaction kettle 2 to rotate to prepare the silver powder for the next batch, the reaction kettle 2 drives the second drain pipe 26 to rotate. The second drain pipe 26 touches the arc-shaped plate 32 and pushes the L-shaped baffle 31 to move toward the drying oven 27. The first spring 35 is compressed. When the L-shaped baffle 31 touches the bottom slope of the conical filter screen 30, it can drive the conical filter screen 30 to move upward. After the L-shaped baffle 31 loses the extrusion of the second drain pipe 26, it resets under the action of the first spring 35, and the conical filter screen 30 moves downward and resets synchronously. Thus, the conical filter screen 30 can move up and down to jolt the silver powder on it, which not only accelerates the solid-liquid separation on the conical filter screen 30 but also accelerates the drying efficiency of the silver powder;

[0081] S7. Organic Coating: After the silver powder on the conical filter screen 30 is dried, open the valve on the discharge pipe 39. The silver powder falls into the ultrasonic oscillator 54 through the discharge pipe 39. Inject the gemini surfactant into the ultrasonic oscillator 54, and perform ultrasonic oscillation (power 300W, time 15min) through the ultrasonic oscillator 54 to adsorb the surfactant on the surface of the silver powder, forming a hydrophobic protective layer. After the ultrasonic oscillation ends, repeat steps S3, S4, and S5 to centrifuge, wash, and dry the silver powder to obtain the required silver powder;

[0082] S8. Mix and stir the silver powder prepared in S6 with an organic carrier, a dispersant, a thixotropic agent, and a coupling agent, and adopt a three-stage dispersion process to ensure the uniformity of the slurry, thereby obtaining the required silver paste.

[0083] However, as is well known to those skilled in the art, the working principles and wiring methods of the glass electrode sensor 40, the vacuum pump 37, the water pump 15, the solenoid valve 16, the drive motor 8, the first heating sheet 25, the electromagnet 11, and the second heating sheet 36 are common knowledge. They all belong to conventional means or well-known common sense, and will not be elaborated here. Those skilled in the art can make arbitrary selections according to their needs or convenience.

[0084] The schematic drawings in the specification of this application are only for illustrative purposes. The dimensions and shapes of the components shown are not actually limited, but only for a schematic representation. During the actual implementation process, the components can be reasonably configured and adjusted according to specific requirements and actual situations.

[0085] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A lithium battery thermal runaway early warning and protection system based on PTC characteristics, characterized in that Comprising: A sensor, made of a carbon-based PTC conductive polymer, with a carrier strip of silver paste, coated with a PI film on the outside, and a high and low temperature resistant double-sided adhesive laminated on one side, having a thickness of 0.2 mm - 0.5 mm, suitable for being installed on the surface or inside a lithium battery to sense the battery temperature and its changes; A signal acquisition circuit, configured to obtain the resistance value of the PTC element and convert it into a voltage signal; A microcontroller (MCU), integrated in a battery management system (BMS), configured to read the voltage signal, calculate the current temperature according to a mathematical model established based on the resistance-temperature characteristic curve of the PTC element, and implement the judgment of abnormal temperature rise and protection logic. Among them, a temperature threshold and a temperature change rate threshold are set, and when the temperature or the temperature change rate exceeds the set threshold, corresponding protection measures are executed.

2. The lithium battery thermal runaway early warning and protection system based on PTC characteristics according to claim 1, wherein The signal acquisition circuit is configured to linearly or non-linearly convert the resistance change of the PTC element into a corresponding voltage signal for the microcontroller (MCU) to perform accurate temperature calculation.

3. The lithium battery thermal runaway warning and protection system based on the PTC characteristic according to claim 2, wherein, The protection measures include: when the calculated temperature value exceeds the set warning threshold, an alarm signal is issued, and the liquid cooling system is controlled to be turned on to reduce the battery temperature; when the calculated temperature value exceeds the set danger threshold, the battery power supply is cut off to prevent thermal runaway; and when the temperature continues to rise and the temperature change rate exceeds the set threshold, fire extinguishing liquid is injected to quickly suppress thermal runaway.

4. The lithium battery thermal runaway warning and protection system based on PTC characteristics according to claim 3, characterized in that, The sensor has the characteristics of being thin, light, and flexible, enabling it to closely adhere to the surface of the lithium battery or be embedded inside it, thereby accurately and real-time sensing the battery temperature and its changes, and improving the accuracy and reliability of early warning protection.

5. Manufacturing equipment for preparing the silver paste in the lithium battery thermal runaway early warning and protection system based on PTC characteristics according to claim 1, characterized in that, Comprising a water bath cylinder (1), a reaction kettle (2) is rotatably connected inside the water bath cylinder (1) through a rotating bearing, a stirring shaft (4) is rotatably connected inside the reaction kettle (2) through a rotating bearing, and a driving structure for stirring and centrifuging the raw materials is provided between the water bath cylinder (1) and the reaction kettle (2). The driving structure includes an L-shaped plate (7) fixedly welded to the top of the water bath cylinder (1); The driving structure further includes a separation structure for separating the nano-silver precipitate in the reaction kettle (2) from the supernatant after centrifugation, facilitating the subsequent washing of the nano-silver precipitate in the reaction kettle (2) with deionized water to ensure the purity of the nano-silver precipitate. The separation structure includes a first drain pipe (21) hermetically sliding through the bottom of the reaction kettle (2), and the top end of the first drain pipe (21) extends into the stirring shaft (4); It further includes a drying oven (27) arranged below the water bath cylinder (1). One side of the drying oven (27) is fixedly penetrated by a feed pipe (28) for injecting the nano-silver precipitate washed from the reaction kettle (2) into the drying oven (27). A drying structure is provided inside the drying oven (27) for drying the nano-silver precipitate in the drying oven (27). The bottom of the reaction kettle (2) is fixedly communicated with a second drain pipe (26).

6. The manufacturing apparatus according to claim 5, wherein The driving structure further includes a driving motor (8) fixed to the top of the L-shaped plate (7). A first bevel gear (9) is fixed to the output shaft of the driving motor (8). The top end of the stirring shaft (4) sequentially passes through the top inner wall of the reaction kettle (2) and the L-shaped plate (7) in a rotating manner. A second bevel gear (18) meshing with the first bevel gear (9) is fixedly sleeved on the outer wall of the top of the stirring shaft (4). The cooperation of the driving motor (8), the first bevel gear (9) and the second bevel gear (18) is used to drive the stirring shaft (4) to complete the stirring of the raw materials in the reaction kettle (2). The bottom of the L-shaped plate (7) is fixedly welded with a first mounting ring (10) through a connecting rod. An electromagnet (11) is fixed to the bottom of the first mounting ring (10). Both the first mounting ring (10) and the electromagnet (11) are sleeved on the outer wall of the stirring shaft (4). A first gear (12) is slidably connected to the outer wall of the stirring shaft (4) through a chute and a slider. A magnetic attraction force is generated between the first gear (12) and the electromagnet (11) to control the lifting of the first gear (12). An internal gear ring (13) is fixed to the top of the reaction kettle (2), and the internal gear ring (13) meshes with the first gear (12). When the first gear (12) descends and meshes with the internal gear ring (13), it is used to drive the reaction kettle (2) to rotate for centrifugal operation. When the first gear (12) moves upward and separates from the internal gear ring (13), the rotation of the stirring shaft (4) is used to stir the raw materials in the reaction kettle (2). First charging hoppers (5) and second charging hoppers (6) are respectively fixedly communicated with both sides of the top of the reaction kettle (2).

7. The manufacturing apparatus according to claim 6, wherein The separation structure further includes a fixing plate (22) fixed to the outer wall of the first drain pipe (21). The fixing plate (22) is located below the reaction kettle (2). A plurality of tension springs (23) are fixed between the top of the fixing plate (22) and the bottom of the reaction kettle (2). A plurality of drain ports (24) are provided on the outer wall of the stirring shaft (4). The plurality of drain ports (24) are all located inside the reaction kettle (2). The top end of the first drain pipe (21) extends into the stirring shaft (4) and closes the drain ports (24). The cooperation between the first drain pipe (21) and the drain ports (24) can remove the supernatant with different thicknesses. A fixing ring (20) is fixed inside the stirring shaft (4) above the first drain pipe (21). A piston rod (19) is hermetically and slidably connected inside the stirring shaft (4), and the bottom end of the piston rod (19) hermetically and slidably penetrates through the fixing ring (20). The bottom end of the piston rod (19) is fixedly connected to the top end of the first drain pipe (21). The top end of the stirring shaft (4) is rotationally communicated with a three-way valve (14). A water pump (15) is fixed to one side of the water bath cylinder (1) through a frame. The liquid inlet end of the water pump (15) is communicated with the water bath cylinder (1) through a pipeline. The liquid outlet end of the water pump (15) is fixedly communicated with one of the liquid inlet ends of the three-way valve (14) through a hose, for injecting clear water into the stirring shaft (4), driving the piston rod (19) and the first drain pipe (21) to move downward, and removing the supernatant with different thicknesses. One side of the water bath cylinder (1) is fixedly communicated with a return pipe (17). The top end of the return pipe (17) is fixedly communicated with the other liquid inlet end of the three-way valve (14). An electromagnetic valve (16) is provided on the outer wall of the return pipe (17). When the electromagnetic valve (16) is opened, under the action of the tension spring (23), the water in the stirring shaft (4) is re-injected into the water bath cylinder (1) to control the reset of the first drain pipe (21), facilitating the separation function to be carried out again later.

8. The manufacturing apparatus according to claim 7, wherein, The drying structure includes a fixed retaining ring (29) fixed inside the drying box (27). A conical filter screen (30) is slidably connected inside the drying box (27) above the fixed retaining ring (29). The fixed retaining ring (29) is used to limit the downward movement of the conical filter screen (30), and it is also convenient to provide a limit for the later up and down movement of the conical filter screen (30). One end of the drying box (27) far from the feed pipe (28) is fixed with a third drain pipe (38) for draining the moisture in the drying box (27) to facilitate later drying. A plurality of second heating sheets (36) are fixed on the inner wall of the drying box (27) for heating the temperature inside the drying box (27) to dry the silver nano-precipitate on the conical filter screen (30). A vacuum pump (37) is fixed on one side of the drying box (27). The intake end of the vacuum pump (37) extends into the drying box (27) through a pipeline for evacuating the drying box (27) to a vacuum, which is not only convenient for later drying but also avoids the oxidation of the silver nano-precipitate with air during drying. An L-shaped baffle (31) is hermetically slid through one side of the drying box (27) close to the feed pipe (28), and the L-shaped baffle (31) extends into the drying box (27) and is located below the conical filter screen (30). An arc-shaped plate (32) is fixed on the side of the L-shaped baffle (31) far from the drying box (27). The arc-shaped plate (32) cooperates with the second drain pipe (26). When the second drain pipe (26) rotates, it drives the L-shaped baffle (31) to move into the drying box (27) by squeezing the arc-shaped plate (32). The L-shaped baffle (31) cooperates with the bottom slope of the conical filter screen (30) to drive the conical filter screen (30) to move upward. After the L-shaped baffle (31) resets, the conical filter screen (30) automatically moves downward. The conical filter screen (30) can move up and down reciprocally, thereby jolting the silver nano, which is not only convenient for separating the moisture in the silver nano but also can accelerate the drying of the silver nano. A substrate (33) is fixed at the top of one side of the L-shaped baffle (31). The substrate (33) is located on one side of the drying box (27). A fixed rod (34) is fixed on one side of the drying box (27) and slidably penetrates through the substrate (33). A first spring (35) is fixed between the substrate (33) and the drying box (27). The first spring (35) is sleeved on the outer wall of the fixed rod (34) for driving the L-shaped baffle (31) to move outward and reset, which is convenient for the L-shaped baffle (31) to be extended into the drying box (27) again to drive the conical filter screen (30) to move upward after being squeezed by the second drain pipe (26) later; It further includes an ultrasonic oscillator (54) arranged below the drying box (27) for organically coating the dried silver nano-precipitate in the drying box (27) so that the surfactant is adsorbed on the surface of the silver powder to form a hydrophobic protective layer. A discharge pipe (39) is fixedly penetrated through the bottom of the conical filter screen (30). The bottom end of the discharge pipe (39) extends through the bottom of the drying box (27) for injecting the silver nano-precipitate into the ultrasonic oscillator (54) to facilitate the later organic coating of the silver nano-precipitate.

9. The manufacturing apparatus according to claim 8, wherein A plurality of first heating sheets (25) are fixedly installed on the inner bottom wall of the water bath cylinder (1) for heating the water in the water bath cylinder (1), so that the raw materials in the reaction kettle (2) react in a water bath environment. A support ring (3) is fixedly welded on the inner bottom wall of the water bath cylinder (1). The top end of the support ring (3) is in sealed rotational connection with the bottom of the reaction kettle (2). The second drain pipe (26) and the first drain pipe (21) both penetrate through the support ring (3). Glass windows (53) are fixedly embedded on one side of both the water bath cylinder (1) and the reaction kettle (2), facilitating the viewing of the intersection of the nano-silver precipitate and the supernatant in the reaction kettle (2). The stirring shaft (4) is made of transparent toughened glass, facilitating the viewing of the position of the first drain pipe (21) through the glass window (53) to complete the subsequent supernatant removal operation.

10. The manufacturing apparatus according to claim 9, wherein A closing plate (42) for closing the bottom end of the second charging hopper (6) is slidably connected to the inner top wall of the reaction kettle (2). A plurality of second springs (43) are fixed to the side of the closing plate (42) away from the stirring shaft (4). One ends of the plurality of second springs (43) are fixed to the same fixing seat (41), and the fixing seat (41) is fixedly welded to the inner top wall of the reaction kettle (2). A first magnet (45) is fixed to the end of the closing plate (42) close to the stirring shaft (4) by bolts. A liquid leakage port (44) is provided in the closing plate (42). The liquid leakage port (44) cooperates with the second charging hopper (6) to drop sodium carbonate in the second charging hopper (6) into the reaction kettle (2) for adjusting the pH value of the solution in the reaction kettle (2). A second magnet (46) located inside the reaction kettle (2) is fixed to the outer wall of the stirring shaft (4) by bolts. A repulsive force is generated between the second magnet (46) and the first magnet (45) to drive the closing plate (42) to move outward, aligning the liquid leakage port (44) with the liquid outlet end of the second charging hopper (6). A second mounting ring (48) is fixed to one inner wall of the reaction kettle (2). A rotating column (50) is rotatably connected inside the second mounting ring (48). A conical platform (49) is fixed to the top end of the rotating column (50). The conical platform (49) is located below the second charging hopper (6) for spreading the solution dripping from the second charging hopper (6) to different positions inside the reaction kettle (2) to avoid local over-alkalinity of the solution inside the reaction kettle (2). A second gear (51) is fixed to the bottom end of the rotating column (50). A U-shaped plate (47) is fixed to one side of the closing plate (42) by bolts. A rack (52) is fixed to one end of the U-shaped plate (47) by bolts. The rack (52) meshes with the second gear (51). The closing plate (42) drives the rack (52) to move under the cooperation of the second magnet (46) and the first magnet (45). The cooperation between the rack (52) and the second gear (51) drives the conical platform (49) to rotate, throwing the solution dripping from the second charging hopper (6) to different positions inside the reaction kettle (2). A glass electrode sensor (40) is fixedly penetrated through one side of the reaction kettle (2) for detecting the pH value of the solution inside the reaction kettle (2).

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