A sensor for high-temperature detection and positioning of lithium-ion batteries and battery packs and its detection method

Abstract

The present invention belongs to the technical field of thermal runaway management of lithium-ion batteries, and particularly relates to a method for detecting and locating overheating of lithium-ion batteries (battery packs) based on temperature sensors. The temperature sensors are temperature sensors based on shape memory alloys or bimetallic strips. The lithium-ion batteries or battery packs are installed with temperature sensors, and the lithium-ion batteries are arranged in a matrix to form battery packs. The overheated batteries in the battery packs are detected and located through the temperature sensors, which is used to solve the problems of overheating detection and location of a large number of batteries in battery packs and energy storage power stations, thereby improving the detection and location efficiency of overheated batteries and timely discovering and locating the batteries that may undergo thermal runaway.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion thermal runaway detection, and particularly relates to a temperature sensor embedded inside a lithium-ion battery and a method for detecting battery overheating using such a sensor. Background Art

[0002] During the charging and discharging processes of lithium-ion batteries, the heat generated due to the insertion, extraction, and movement of lithium ions in the positive and negative electrode materials will cause the temperature of the battery to rise. In addition, high-temperature weather and harsh usage environments will also cause the temperature of the battery to rise. When a lithium-ion battery is overheated, side reactions that affect the battery performance and reduce stability will occur inside the battery. When the temperature exceeds the thermal runaway temperature of the battery, it will quickly trigger thermal runaway of the battery, generating a large amount of toxic fumes, flames, or even explosions. Moreover, since the batteries are densely arranged in the battery pack, the large amount of heat released by the thermal runaway of one battery will cause the surrounding batteries to also experience thermal runaway, triggering a fire in the entire battery pack. In large-scale energy storage power stations and battery warehouses, this will lead to serious accident consequences.

[0003] Therefore, rapid and reliable monitoring of the battery temperature is very important for the safe large-scale use of lithium-ion batteries. However, there are a large number of batteries in a lithium-ion battery pack, and it is difficult for traditional temperature sensors to be attached to each battery. Moreover, too many sensors will increase the complexity of the detection circuit, making the development and maintenance of the temperature monitoring system more difficult. In addition, the heat generation of the battery is inside the battery, and it takes time for the internal high temperature to conduct to the battery surface, and the temperature on the battery surface is uneven in each area. Even if traditional temperature sensors such as thermocouples and thermal resistors are attached to the battery surface, due to their point temperature measurement, they cannot detect the uneven temperature on the battery surface. Currently, some detection methods use optical fibers embedded in the battery for internal temperature measurement, which can obtain the internal temperature of the battery better, but the usage environment requirements for optical fiber temperature measurement are relatively high, and the entire set of optical fiber transceiver and processing equipment is expensive, and currently it can only be applied at the laboratory level. Therefore, there is an urgent need for a battery temperature sensor that is inexpensive, easy to detect, has reliable signals, and is easy to arrange over a large area, for real-time detection of battery overheating and location of overheated batteries. Summary of the Invention

[0004] The present invention provides a sensor and its detection method for high-temperature detection and location of lithium-ion batteries and battery packs, which are used to solve the overheating detection and location of a large number of batteries in battery packs and energy storage power stations, and improve the detection and location efficiency.

[0005] To achieve the above object, the present invention is implemented as follows:

[0006] A temperature sensor, comprising a housing, a central shaft and a shaft sleeve. The central shaft and the shaft sleeve are arranged in the housing, and there is electrical insulation between the housing and the central shaft. The shaft sleeve is a metal component, including a fixed end fixedly connected to the central shaft, a sliding end slidably connected to the central shaft, and a temperature-controlled deformation section located between the fixed end and the sliding end. The temperature-controlled deformation section is made of a temperature-variable metal material. When the temperature reaches the deformation threshold of the temperature-controlled deformation section, the temperature-controlled deformation section deforms into an arch shape, causing the sliding end to approach the fixed end. The temperature-controlled deformation section abuts against the housing and is electrically connected to the housing.

[0007] The temperature-variable metal described in the present invention refers to a metal whose shape changes when the temperature changes.

[0008] Preferably, the housing includes a metal housing main body and end caps made of electrically insulating materials provided at both ends of the metal housing main body. The central shaft is detachably connected to the end caps; the end caps are detachably connected to the housing main body; the central shaft is a hollow tubular structure made of a metal material, and a diode with unidirectional conductivity is encapsulated in its hollow. The anode of the diode is electrically connected to the inner side wall of the central shaft; there are also two lead-out terminals, namely terminal A and terminal B. Among them, terminal B is electrically connected to the housing, terminal A is electrically connected to the cathode of the diode, and there is electrical insulation between terminal A and the central shaft; the temperature-controlled deformation section is a metal sheet made of a shape memory metal or a bimetallic sheet formed by superimposing two metal sheets with different coefficients of thermal expansion.

[0009] The shape memory metal can deform and restore its original shape at different temperatures. Using this property for temperature detection, its repeatability can reach hundreds of thousands of times. Therefore, it can be used for a long time without worrying about the reliability of detection. The present invention utilizes the property that the shape memory metal deforms at high temperatures and returns to its original shape when the temperature decreases to detect battery overheating. In addition, the property that the bimetallic sheet has different shapes at different temperatures can also be used to detect the overheating temperature of the battery.

[0010] Preferably, the number of metal sheets of the temperature-controlled deformation section is multiple, and the multiple metal sheets are uniformly arranged circumferentially along the central shaft. When deforming at high temperature, the overall shaft sleeve presents a lantern frame structure. Such a design can ensure the isotropy of the sensor, that is, no matter which direction inside the battery has a high temperature, at least one temperature-controlled deformation section can be deformed, so that the detection of high temperature is not affected by the installation position of the sensor, and the detection accuracy is high.

[0011] A lithium-ion battery including the above temperature sensor, at least one temperature sensor is embedded inside the lithium-ion battery. The terminal A of each temperature sensor is connected to the same lead wire, which is called the total terminal A of the battery unit, and the terminal B of each temperature sensor is connected to the same lead wire, which is called the total terminal B of the battery unit.

[0012] Preferably, the shape of the lithium-ion battery is cylindrical, and the temperature sensor is arranged in the cavity of the central core column of the wound battery inside the lithium-ion battery.

[0013] Preferably, the shape of the lithium-ion battery is square, and the temperature sensor is arranged in the corner cavity inside the lithium-ion battery.

[0014] A lithium-ion battery pack assembled from the above lithium-ion batteries, with multiple lithium-ion batteries arranged in an M-row and N-column lithium-ion battery pack in a row-column matrix form;

[0015] The A ends of the battery cells in each row of lithium-ion batteries are connected to the same lead wire and called row lead terminals, so there are M row lead terminals in total, and each row lead terminal corresponds to a unique number L i , i ∈ [1, M],; The B ends of the battery cells in each column of lithium-ion batteries are connected to the same lead wire and called column lead terminals, so there are N row lead terminals in total, and each row lead terminal corresponds to a unique number I j , j ∈ [1, N];, then each battery corresponds to a unique number Batij.

[0016] Fourthly, the present invention provides a method for detecting and locating overheated batteries in the above lithium-ion battery pack:

[0017] Including a first multiplexer, having M input terminals and one first output terminal;

[0018] A second multiplexer, having N input terminals and one second output terminal;

[0019] A power supply, the working DC power supply for detecting overheating of the lithium-ion battery;

[0020] A fixed-value resistor, one end of which is electrically connected to the second output terminal of the second multiplexer, and the other end is electrically connected to the positive pole of the power supply. The resistance value of this fixed-value resistor is relatively large, so that when a circuit is formed, the total resistance value of the wires and other components in the circuit is much smaller than the resistance value of the fixed-value resistor, and the voltage across the fixed-value resistor is very large, facilitating the voltage measuring instrument to detect it significantly.

[0021] A voltage measuring instrument, connected in parallel with the fixed-value resistor;

[0022] The method for detecting and locating overheated batteries includes the following steps:

[0023] Step 1 S1: Circuit connection

[0024] The M input terminals of the first multiplexer are correspondingly electrically connected to the row lead terminals of the M rows of lithium-ion batteries, that is, the i-th input terminal of the first multiplexer is electrically connected to the row lead terminal L of the i-th row of lithium-ion batteries i electrically connected, and its first output terminal is electrically connected to the negative pole of the power supply;

[0025] The N input terminals of the second multiplexer are respectively electrically connected to the column lead terminals of the corresponding N columns of lithium-ion batteries, that is, the j-th input terminal of the second multiplexer is electrically connected to the column lead terminal lj of the corresponding j-th column of lithium-ion batteries j Its second output terminal is electrically connected to the positive pole of the power supply through a fixed-value resistor;

[0026] Step S2: Overheat detection and location of the battery

[0027] S2-1: First, switch the input terminal of the first multiplexer to the 1st input terminal, and keep the lead terminal of the 1st row connected to the negative pole of the power supply;

[0028] S2-2: Then, switch the input terminal of the second multiplexer to the 1st input terminal, and keep the lead terminal of the 1st column connected to the positive pole of the power supply;

[0029] S2-3: Observe the voltmeter. If there is no voltage, the lithium-ion battery Bat11 in the first row and first column has not overheated; if the voltage rises, the lithium-ion battery Bat11 in the first row and first column has overheated;

[0030] S2-4: Switch the input terminal of the second multiplexer to the 2nd input terminal, and keep the lead terminal of the 2nd column connected to the positive pole of the power supply;

[0031] S2-5: Observe the voltmeter. If there is no voltage, the lithium-ion battery Bat 12 in the first row and second column has not overheated; if the voltage rises, the lithium-ion battery Bat 12 in the first row and second column has overheated;

[0032] S2-6: Switch the input terminal of the second multiplexer to the 3rd input terminal, and repeat steps S2-4 and S2-5 until the input terminal of the second multiplexer is switched to the Nth input terminal, and end the detection of whether the lithium-ion battery Bat1j in the first row has overheated;

[0033] S2-7: Switch the input terminal of the first multiplexer to the 2nd input terminal, and keep the lead terminal of the 2nd row connected to the negative pole of the power supply; sequentially switch the input terminal of the second multiplexer from the 1st input terminal to the Nth input terminal, and end the detection of whether the lithium-ion battery Bat2j in the second row has overheated;

[0034] S2-8: Sequentially switch the input terminal of the first multiplexer to the 3rd input terminal, and keep the lead terminal of the 3rd row connected to the negative pole of the power supply; sequentially switch the input terminal of the second multiplexer from the 1st input terminal to the Nth input terminal, and end the detection of whether the lithium-ion battery Bat 3j has overheated;

[0035] ……

[0036] S2-9: Switch the input terminal of the first multiplexer to the i-th input terminal, and sequentially switch the input terminals of the second multiplexer from the 1st input terminal to the N-th input terminal to end the detection of whether the lithium-ion battery Batij in the i-th row has overheated.

[0037] S2-10: Repeat step 2-9 until the input terminal of the first multiplexer is switched to the M-th input terminal, and sequentially switch the input terminals of the second multiplexer from the 1st input terminal to the N-th input terminal to end the detection of whether the lithium-ion battery BatMj in the M-th row has overheated; that is, complete the overheat detection of the entire battery pack.

[0038] The beneficial effects of the present invention compared with the prior art are as follows:

[0039] 1. The temperature sensor described in the present invention uses a metal or bimetallic sheet with a temperature memory effect. After a special structural design, it is dedicated to detecting overheating inside the battery. The overheating inside the battery is more sensitive than external detection. Using a short-circuit signal as the overheat detection signal makes the detection circuit simpler and the presence or absence of the signal more reliable.

[0040] 2. According to requirements, the housing of the temperature sensor can be made cylindrical, or it can be made into an elliptical cylinder, triangular prism, or square prism according to the shape and length of the internal void of the battery to adapt to the overheat detection of different-shaped internal voids of the battery. Moreover, the internal structure of the sensor is simple and compact, and it can be arranged in the idle space inside the battery, which can not only enhance the overall strength of the battery but also realize the overheat detection function.

[0041] 3. By connecting all the temperature sensors in the battery pack to the circuit to form a matrix battery pack overheat detection circuit, and embedding diodes in the temperature sensors to ensure the unidirectional conductivity of the sensors and combining them with the external matrix circuit, the detection and positioning of multiple overheated batteries can be realized, and the overheat detection of the entire battery pack can be achieved in a simple circuit.

[0042] 4. Due to the simple structure and convenient detection of the temperature sensor, it can be well applied to automotive battery packs and large-scale energy storage battery packs, and can realize the single-cell and multi-cell positioning of overheated batteries in the battery pack at low cost, which is convenient to link the sensors and detection methods involved in this patent with other systems. Description of the Drawings

[0043] Figure 1 It is an exploded view of the temperature sensor in Embodiment 1;

[0044] Figure 2 It is a schematic diagram of the shape of the shaft sleeve at high temperature in Embodiment 2;

[0045] Figure 3 Schematic diagram of the state of the temperature sensor at low temperature in Embodiment 2. The upper part in the figure is the simplified logic diagram of the temperature sensor, and the lower part is the cross-sectional view of the temperature sensor;

[0046] Figure 4 Schematic diagram of the state of the temperature sensor at high temperature in Embodiment 2. The upper part in the figure is the simplified logic diagram of the temperature sensor, and the lower part is the cross-sectional view of the temperature sensor;

[0047] Figure 5 Schematic diagram of the battery cross-section after the temperature sensor is combined with a cylindrical battery in Embodiment 3;

[0048] Figure 6 Schematic diagram of the battery cross-section after the temperature sensor is combined with a square battery in Embodiment 4;

[0049] Figure 7 Schematic diagram of the temperature sensor used to detect an overheated lithium-ion battery system in Embodiment 5.

[0050] Figure 8 Schematic diagram of a system for detecting an overheated lithium-ion battery using a temperature sensor without a diode;

[0051] Figure 9 Schematic diagram of a system for detecting an overheated lithium-ion battery using a temperature sensor with a diode.

[0052] In the figure: 100. Temperature sensor, 101. Housing, 1011. Metal housing main body, 1012. End cap, 102. Central axis, 103. Bush, 1031. Fixed end, 1032. Temperature-controlled deformation section, 1033. Sliding end, 104. Diode, 105. B terminal, 106. A terminal, 200. Cylindrical lithium-ion battery, 201. Cylindrical battery housing, 202. Cylindrical battery cell, 203. Battery central core column, 300. Square lithium-ion battery, 301. Square battery housing, 302. Square battery cell, 5011. First multiplexer, 5012. Second multiplexer, 502. Power supply, 503. Fixed-value resistor, 504. Voltage measuring instrument. Detailed implementation manners

[0053] Now, the subject matter described herein will be discussed with reference to example embodiments. It should be understood that discussing these embodiments is only to enable those skilled in the art to better understand and thus implement the subject matter described herein. Without departing from the protection scope of the content of this specification, the functions and arrangements of the elements discussed can be changed. Each example can omit, substitute, or add various processes or components as needed. Additionally, the features described relative to some examples can also be combined in other examples. Embodiment 1:

[0054] Please refer to Figure 1 , the temperature sensor 100 includes a housing 101 made of a metal material, a central shaft 102, and a bushing 103 made of a shape memory metal. The central shaft 102 and the bushing 103 are disposed in the housing 101, and electrical insulation is provided between the housing 101 and the central shaft 102.

[0055] Electrical insulation between the housing 101 and the central shaft 102 is achieved as follows: The housing 101 includes a metal housing main body 1011 and end caps 1012 made of an electrical insulating material disposed at both ends of the metal housing main body 1011. The end caps 1012 have a large annular protrusion adapted to the inner diameter of the housing main body 1011 and a small annular protrusion adapted to the outer diameter of the central shaft 102. Through holes are provided on the end caps 1012 corresponding to the positions of the small annular protrusions. The central shaft 102 is inserted into the small annular protrusions of the two end caps 1012, and the central shaft 102 is detachably connected to the end caps 1012; the housing main body 1011 is inserted onto the large annular protrusions of the two end caps 1012, the end caps 1012 are detachably connected to the housing main body 1011, and the central shaft 102 does not contact the housing main body 1011.

[0056] Each end of the bushing 103 has a ring, which can be a closed ring or an open ring. The open ring is better for installation and fixation compared to the closed ring, and the open ring is also more adaptable to thermal expansion and contraction. Among them, the end with a smaller inner diameter is the fixed end 1031, and the end with a larger inner diameter is the sliding end 1033. The fixed end 1031 is fixedly connected and electrically connected to the central shaft 102, for example, by riveting or spot welding. The sliding end 1033 can slide on the central shaft 102. The temperature control deformation section 1032 is located between the fixed end 1031 and the sliding end 1033. When the temperature reaches the deformation threshold of the temperature control deformation section 1032, the temperature control deformation section 1032 deforms into an arch shape, causing the sliding end to approach the fixed end, and the control deformation section 1032 abuts against the housing 101 and is electrically connected to the housing 101.

[0057] The temperature control deformation section 1032 is a nickel-titanium shape memory metal with a two-way memory effect. Since the safe operating temperature of a lithium-ion battery is generally 0 to 50 °C, and the starting temperature of the exothermic side reaction inside the lithium-ion battery is about 75 °C, the deformation threshold is preferably 60 °C. When it reaches 60 °C, it bends and deforms, and when it returns to 40 °C, it returns to a flat shape. The memory metal is used as the material of the temperature control deformation section.

[0058] The number of metal sheets of the temperature control deformation section 1032 is multiple. As used in the present invention, "multiple" means two or more. In this embodiment, the number of metal sheets of the temperature control deformation section 1032 is two.

[0059] The central axis 102 is a hollow tubular structure. The through holes on the two end caps 1012 communicate with the hollow of the central axis 102. A diode 104 with unidirectional conductivity is encapsulated in the hollow of the central axis 102, and the anode of the diode 104 is electrically connected to the central axis 102.

[0060] The temperature sensor 100 further includes two lead-out terminals, a terminal A 106 and a terminal B 105. Among them, the terminal B 105 is electrically connected to the housing 101, the terminal A 106 is electrically connected to the cathode of the diode 104, and the terminal A 106 is insulated from the central axis 102. For example, an insulating outer sleeve is sleeved on a section of the terminal A 106 that may come into contact with the central axis 102.

[0061] In other embodiments, the temperature-controlled deformation section can adopt a bimetallic strip. The so-called bimetallic strip refers to two metal strips of the same size but different thermal expansion coefficients (such as a copper strip and an iron strip) connected, such as riveted or welded together to form a bimetallic strip. Since the requirement for the temperature-controlled deformation section 1032 is to bend and deform at a certain high temperature and return to its original flat shape after cooling, the deformation threshold is preferably 60°C. Through the design of the thickness and shape of the metal strip, it is achieved that when the temperature reaches 60°C, it bends and deforms, and when it cools to 40°C, it returns to flat. Therefore, a bimetallic strip can be used as the material for the temperature-controlled deformation section 1032.

[0062] The advantages of the bimetallic strip are easy material selection and low manufacturing cost. Embodiment 2:

[0063] Please refer to Figures 2-4 , the difference between this embodiment and the first embodiment is that the temperature-controlled deformation section 1032 is composed of six metal strips, and the six metal strips are evenly arranged circumferentially along the central axis 102. When deforming at high temperature, the shaft sleeve 103 as a whole presents a lantern frame structure.

[0064] The advantages of this embodiment are that the contact area between the temperature-controlled deformation section 1032 and the housing 101 is large, and the structure is stable.

[0065] The rest is the same as the first embodiment.

[0066] The above two temperature sensors 100 act as temperature control switches.

[0067] Please refer to Figure 3 , at low temperature, the temperature-controlled deformation section 1032 does not arch up and shrinks and closes, then the shaft sleeve 103 does not abut against the housing 101. Since the shaft sleeve 103 is fixedly connected to the central axis 102 through the fixed end 1031, the housing 101 and the central axis 102 are not electrically connected, which is equivalent to the switch being in the off state.

[0068] Please refer to Figure 4, at high temperatures, it arches away from the central axis 102 until it abuts against the inner wall of the outer shell 101. Since both the bushing 103 and the outer shell 101 are made of metal, their abutment, when energized, is an electrical connection, equivalent to the switch being in the closed state. Embodiment 3:

[0069] In this embodiment, the temperature sensors 100 in the first and second embodiments are embedded in the cylindrical lithium-ion battery 200 to detect overheating of the lithium-ion battery 200.

[0070] Please refer to Figure 5 , the cylindrical lithium-ion battery 200 includes a cylindrical battery outer shell 201, a cylindrical battery cell 202, and a battery central core column 203. Inside the cylindrical battery 200, there is a wound cylindrical battery cell 202. There is a cylindrical hollow space in the central part of the wound battery cell. Generally, a cylindrical battery central core column 203 will be placed in this space to improve the stability and mechanical strength of the battery cell. At least one of the above temperature sensors 100 is embedded inside the cylindrical battery 200 as the battery central core column 203 during the battery manufacturing stage, and then overheating of the battery is detected from the inside. Embodiment 4:

[0071] In this embodiment, the temperature sensors 100 in the first and second embodiments are embedded in the square lithium-ion battery 300 for overheating of the lithium-ion battery 300.

[0072] As Figure 6 shown, the above temperature sensors 100 are embedded during the manufacturing of the square lithium-ion battery 300 to detect and locate overheating of the square lithium-ion battery 300. Inside the square lithium-ion battery 300 is a wound square battery cell 302. Each corner of the battery cell 302 forms an arc due to the wound structure. Therefore, a triangular-like gap is formed between the square battery cell 302 and the square battery outer shell 301 at each corner. During the manufacturing stage of the square lithium-ion battery 300, a temperature sensor 100 can be placed in this gap to detect overheating inside the square lithium-ion battery 300. In addition, the outer shell 101 of the temperature sensor 100 can be made into other different shapes to adapt to the shape and length of the battery internal gap, such as an elliptical cylinder, a triangular prism, or a square prism. And the shape and length of the bushing 103 on the central axis 102 inside the sensor can be adapted to the outer shell 101 to ensure that overheating of the battery can be detected throughout the full length of the sensor.

[0073] In Embodiments 3 and 4, if there are multiple temperature sensors 100, the A terminals 106 of each temperature sensor 100 are connected to the same lead wire, which is called the total A terminal of the battery unit, and the B terminals 105 of each temperature sensor 100 are connected to the same lead wire, which is called the total B terminal of the battery unit. Embodiment 5:

[0074] According to the first and second embodiments, the temperature sensor 100 can be simplified into a logic structure as shown in Figure 3 and Figure 4 . The temperature sensor 100 is regarded as a switch that automatically closes at high temperatures and automatically disconnects at low temperatures. Since the central axis inner diode 104 is embedded inside the central axis 102, the temperature sensor 100 can only conduct the external circuit unidirectionally.

[0075] Please refer to Figure 7 . In this embodiment, multiple lithium-ion batteries of the third or fourth embodiment are arranged in a row-column matrix form into an M-row and N-column lithium-ion battery pack. The total A ends of the battery cells of each row of lithium-ion batteries are connected to the same lead wire, which is called the row lead terminal, and the total B ends of the battery cells of each column of lithium-ion batteries are connected to the same lead wire, which is called the column lead terminal. Overheat detection and positioning are performed on the lithium-ion batteries in the battery pack.

[0076] To achieve the detection and positioning of overheated batteries, sensors at different positions can be formed into an overheated battery detection and positioning matrix circuit as shown in Figure 7 . In this embodiment, a four-row and four-column matrix is used as an illustration. The overheat detection and positioning logic of a larger sensor matrix can be deduced with reference to this embodiment.

[0077] During detection, the following are used: a first multiplexer 5011, having 4 input terminals and 1 first output terminal;

[0078] a second multiplexer 5012, having 4 input terminals and 1 second output terminal;

[0079] a power supply 502, which is the working DC power supply for lithium-ion battery overheat detection;

[0080] a fixed-value resistor 503, one end of which is electrically connected to the second output terminal of the second multiplexer 5012, and the other end is electrically connected to the positive pole of the power supply 502. The resistance value of the fixed-value resistor 503 is relatively large so that a voltage value that can be clearly observed by the voltage measuring meter 504 can be formed across the fixed-value resistor 503. For example, the rated voltage of the power supply is 5V, the resistance value of the fixed-value resistor 503 is 1000 ohms, and the total resistance value of the wires and other components in the circuit is several ohms or dozens of ohms. In this way, when the temperature sensor 100 is closed, a voltage close to 5V is formed across the fixed-value resistor 503, and then the change in the value on the voltage measuring meter 504 can be clearly observed.

[0081] a voltage measuring meter 504, which is connected in parallel with the fixed-value resistor 503;

[0082] The specific method for detecting and positioning overheated batteries is as follows:

[0083] Step 1 S1: Circuit connection

[0084] Please refer to Figures 7-9 , the row lead terminals of each row of batteries are respectively connected to one of the input terminals of the first multiplexer 5011. The row lead terminals of the 1st - 4th rows are positioned as the a, b, c, d input terminals of the first multiplexer 5011 from top to bottom. That is, the row lead terminal of the 1st row is electrically connected to the a input terminal of the first multiplexer 5011, the 2nd row is electrically connected to the b input terminal...; the column lead terminals of each column of batteries are respectively connected to one of the input terminals of the second multiplexer 5012. The column lead terminals of the 1st - 4th columns are positioned as the A, B, C, D input terminals of the second multiplexer 5012 from left to right. That is, the column lead terminal of the 1st column is electrically connected to the A input terminal of the second multiplexer 5012, the 2nd column is electrically connected to the B input terminal.... Therefore, each battery corresponds to a unique matrix number. For example, the battery at the position of three rows and two columns corresponds to the number cB, and the battery at the position of four rows and three columns corresponds to the number dC.

[0085] After connecting the input terminal of the first multiplexer 5011 to the row lead terminal, the output terminal of the first multiplexer 5011 is connected to the negative pole of the power supply 502; after connecting the input terminal of the second multiplexer 5012 to the column lead terminal, the output terminal of the second multiplexer 5012 is connected to the positive pole of the power supply 502 through a fixed - value resistor 503;

[0086] Step two S2: Detection and location of overheated batteries

[0087] S2 - 1: First, switch the input terminal of the first multiplexer 5011 to the 1st input terminal, and keep the 1st row lead terminal connected to the negative pole of the power supply 502;

[0088] S2 - 2: Then, switch the input terminal of the second multiplexer 5012 to the 1st input terminal, and connect the 1st column lead terminal to the positive pole of the power supply 502;

[0089] S2 - 3: Observe the voltage measuring meter 504. If there is no voltage, the lithium - ion battery in the first row and the first column (corresponding number is aA) has not overheated; if there is a voltage increase, the lithium - ion battery in the first row and the first column (corresponding number is aA) has overheated;

[0090] S2 - 4: Switch the input terminal of the second multiplexer 5012 to the 2nd input terminal, and connect the 2nd column lead terminal to the positive pole of the power supply 502;

[0091] S2 - 5: Observe the voltage measuring meter 504. If there is no voltage, the lithium - ion battery in the first row and the second column (corresponding number is aB) has not overheated; if there is a voltage increase, the lithium - ion battery in the first row and the second column (corresponding number is aB) has overheated;

[0092] S2-6: Switch the input terminal of the second multiplexer 5012 to the 3rd input terminal, and repeat steps S2-4 and S2-5 until the input terminal of the second multiplexer 5012 is switched to the 4th input terminal, and then end the overheat detection and positioning of the lithium-ion batteries aA, aB, aC, and aD in the first row;

[0093] S2-7: Switch the input terminal of the first multiplexer 5011 to the 2nd input terminal, and keep the lead terminals of the 2nd row connected to the negative pole of the power supply 502; sequentially switch the input terminal of the second multiplexer 5012 from the 1st input terminal to the 4th input terminal, and then end the overheat detection and positioning of the lithium-ion batteries bA, bB, bC, and bD in the second row;

[0094] S2-8: Sequentially switch the input terminal of the first multiplexer 5011 to the 3rd input terminal, and keep the lead terminals of the 3rd row connected to the negative pole of the power supply 502; sequentially switch the input terminal of the second multiplexer (5012) from the 1st input terminal to the 4th input terminal, and then end the overheat detection and positioning of the lithium-ion batteries cA, cB, cC, and cD in the third row;

[0095] S2-9: Sequentially switch the input terminal of the first multiplexer 5011 to the 4th input terminal, and keep the lead terminals of the 4th row connected to the negative pole of the power supply 502; sequentially switch the input terminal of the second multiplexer (5012) from the 1st input terminal to the 4th input terminal, and then end the overheat detection and positioning of the lithium-ion batteries dA, dB, dC, and dD in the fourth row;

[0096] S2-10: Complete the overheat detection and positioning of the entire battery pack.

[0097] Specifically, when none of the batteries overheat, there is an open circuit between the fixed resistor 503 and the power supply 502 in the circuit, and thus no voltage can be detected across the fixed resistor 503. When a certain battery in the battery pack overheats, a closed circuit is formed between the fixed resistor 503 and the power supply 502, and at this time, a relatively large voltage can be detected across the fixed resistor 503. The specific process is as follows: The multiplexer 501 connected to the horizontal circuits cyclically connects different horizontal circuits to the circuit, and at the same time, the multiplexer 501 connected to the vertical circuits cyclically connects different vertical circuits to the circuit. Its frequency is set such that the multiplexer 501 in the horizontal circuits switches to the next horizontal circuit after the multiplexer 502 in the vertical circuits has cyclically connected all the vertical circuits to the circuit once. After all the horizontal circuits are cyclically connected to the circuit for one cycle by the multiplexer 501, all the wiring possibilities in the matrix sensor are traversed once. Record which sensors corresponding to the numbers can detect voltage across the fixed resistor when connected to the circuit, and then the batteries at the positions corresponding to these sensors are in the overheated state. For example, when the battery at the second row and fourth column overheats, the temperature sensor 100 provided thereon will close to form a closed circuit. Then, when the horizontal circuit b and the vertical circuit D are connected to the circuit by the multiplexer 501, a voltage will be detected across the fixed resistor 503, and the overheated battery position can be determined by combining this voltage signal with the sensor number bD. Similarly, when multiple overheated batteries appear in the battery pack, multiple sensor numbers will be recognized, and thus the overheating of multiple batteries can be quickly located.

[0098] A light-emitting diode can also be used to replace the voltage measuring instrument 504. The negative electrode of the light-emitting diode is electrically connected to the second input terminal of the second multiplexer 5012, and the negative electrode of the light-emitting diode is electrically connected to the negative electrode of the power supply 502. If an overheated lithium-ion battery is detected, the light-emitting diode will emit light, which is more convenient and intuitive compared to using the voltage measuring instrument 504 to measure voltage.

[0099] The diode 104 in the temperature sensor 100 in this application is designed to detect and locate overheated lithium-ion batteries in a battery pack composed of multiple lithium-ion batteries as in the embodiment. Without adding the diode 104, the occurrence of multiple overheated batteries will cause the system to wrongly mark the batteries that did not overheat originally as overheated.

[0100] As Figure 8 shown, Figure 8Schematic diagram of a system for detecting overheated lithium-ion batteries using a temperature sensor without a diode. The temperature sensors without the diode 104 will form the sensor matrix described in the figure. When the batteries at positions bB, bC, and cC overheat, these three sensors will remain conductive. Since the sensors do not have unidirectional conductivity, current can bypass the sensor numbered cB through the thickened path in the figure, enabling a conductive path to be presented when the horizontal circuit c and the vertical circuit B are connected to the detection circuit, so that a voltage can be detected across the fixed-value resistor 503, even if the sensor numbered cB is not conductive at this time.

[0101] As Figure 9 shown, Figure 9 Schematic diagram of a system for detecting overheated lithium-ion batteries using a temperature sensor 100 with a unidirectional conduction diode 104.

[0102] After adding the diode 104, since the power supply in the detection circuit is a DC power supply, current cannot flow backward through the sensor numbered bC, preventing the detection circuit from misidentifying a non-overheated battery as overheated and causing a false alarm.

Claims

1. A lithium ion battery comprising a temperature sensor, characterized in that: At least one temperature sensor (100) is embedded in a lithium-ion battery, and the A connection terminals (106) of each temperature sensor (100) in each battery are connected to the same lead wire, which is called the battery cell A terminal, and the B connection terminals (105) of each temperature sensor (100) are connected to the same lead wire, which is called the battery cell B terminal; The temperature sensor comprises a housing (101), a central shaft (102) and a shaft sleeve (103); the central shaft (102) and the shaft sleeve (103) are arranged in the housing (101); the housing (101) and the central shaft (102) are electrically insulated; the shaft sleeve (103) is a metal component, comprising a fixed end (1031) fixedly connected to the central shaft (102), a sliding end (1033) slidably connected to the central shaft (102), and a temperature-controlled deformation section (1032) located between the fixed end (1031) and the sliding end (1033); the temperature-controlled deformation section (1032) is made of a temperature-dependent metal material; when the temperature reaches a deformation threshold of the temperature-controlled deformation section (1032), the temperature-controlled deformation section (1032) is deformed into an arch shape, so that the sliding end approaches the fixed end; the temperature-controlled deformation section (1032) abuts against the housing (101) and is electrically connected to the housing (101); The housing (101) comprises a metal housing body (1011) and end caps (1012) made of an electrically insulating material and arranged at both ends of the metal housing body (1011); the central shaft (102) and the end caps (1012) are detachably connected; the end caps (1012) and the housing body (1011) are detachably connected; the central shaft (102) is a hollow tubular structure made of a metal material, and a unidirectionally conductive diode (104) is encapsulated in the hollow thereof; the anode of the diode (104) is connected to the central shaft ( 102) inner wall is electrically connected; it also includes two lead-out terminals, namely, an A terminal (106) and a B terminal (105), wherein the B terminal (105) is electrically connected to the housing (101), the A terminal (106) is electrically connected to the cathode of the diode (104), and the A terminal (106) and the central axis (102) are electrically insulated from each other; the temperature control deformation section (1032) is a metal sheet made of memory metal or a bimetallic sheet formed by stacking two metal sheets with different thermal expansion coefficients; The temperature-controlled deformation section (1032) comprises a plurality of metal sheets, which are evenly arranged in the circumferential direction of the central axis (102); when deformed at high temperature, the shaft sleeve (103) as a whole presents a lantern skeleton structure.

2. The lithium-ion battery according to claim 1, characterized in that The lithium ion battery is cylindrical in shape, and the temperature sensor (100) is arranged in a cavity of a wound battery central core column (203) inside the lithium ion battery.

3. The lithium-ion battery according to claim 2, characterized in that The lithium ion battery is square in shape, and the temperature sensor (100) is arranged at a corner of the internal cavity of the lithium ion battery.

4. A lithium ion battery pack comprising a lithium ion battery according to any one of claims 1 to 3, characterized in that: A plurality of lithium-ion batteries are arranged in a row-column matrix to form a lithium-ion battery pack with M rows and N columns; The A ends of the battery cells in each row of lithium-ion batteries are connected to the same lead-out wire, which is called a row lead-out terminal. There are M row lead-out terminals in total, and each row lead-out terminal corresponds to a unique number L. i , i∈[1,M]; the B terminals of the battery cells in each column of lithium-ion batteries are connected to the same lead-out line, which is called the column lead-out terminal. There are N row lead-out terminals in total, and each row lead-out terminal corresponds to a unique number l j , j∈[1,N]; each battery corresponds to a unique number Bat ij .

5. The battery overheat detection method of the lithium-ion battery pack according to claim 4, characterized in that: It comprises a first multiplexer (5011) having M input terminals and a first output terminal; A second multiplexer (5012) having N input terminals and a second output terminal; Power supply (502), a working DC power supply for lithium-ion battery overheat detection; A fixed value resistor (503), one end of which is electrically connected to the second output end of the second multiplexer (5012), and the other end of which is electrically connected to the positive electrode of the power supply (502); A voltage measuring meter (504) is connected in parallel with a fixed value resistor (503); The overheated battery detection and positioning method comprises the following steps: Step 1 S1: Circuit connection The M input terminals of the first multiplexer (5011) are electrically connected to the row lead terminals of the M rows of lithium-ion batteries, that is, the i-th input terminal of the first multiplexer (5011) is electrically connected to the row lead terminals L of the i-th row of lithium-ion batteries. i electrically connected, with its first output terminal being electrically connected to the negative electrode of a power source (502); The N input terminals of the second multiplexer (5012) are electrically connected to the column lead-out terminals of the corresponding N columns of lithium-ion batteries, that is, the j-th input terminal of the second multiplexer (5012) is electrically connected to the column lead-out terminal l of the corresponding j-th column of lithium-ion batteries. j The second output terminal is electrically connected to the positive electrode of the power source (502) via a fixed value resistor (503); Step 2 S2: Detection and location of overheated batteries S2-1: first switch the input end of the first multiplexer (5011) to the first input end, and keep the first row lead terminal connected to the negative pole of the power supply (502); S2-2: Switch the input end of the second multiplexer (5012) to the first input end, and keep the first column lead terminal connected to the positive electrode of the power supply (502); S2-3: Observe the voltage measurement table (504). If there is no voltage, the lithium-ion battery Bat in the first row and first column 11 No overheating occurred; If the voltage rises, the lithium-ion battery Bat in the first row and first column 11 Overheating occurs; S2-4: Switch the input end of the second multiplexer (5012) to the second input end, and keep the second column lead terminal connected to the positive pole of the power supply (502); S2-5: Observe the voltage measurement table (504). If there is no voltage, the lithium-ion battery Bat in the first row and second column 12 No overheating occurred; If the voltage rises, the lithium-ion battery Bat in the first row and second column 12 Overheating occurs; S2-6: Switch the input end of the second multiplexer (5012) to the third input end, repeat steps S2-4 and S2-5 until the input end of the second multiplexer (5012) is switched to the Nth input end, and the first row of lithium-ion batteries Bat is terminated. 1j Detection of overheating; S2-7: Switch the input end of the first multiplexer (5011) to the second input end, keep the second row lead terminal connected to the negative pole of the power supply (502); switch the input end of the second multiplexer (5012) from the first input end to the Nth input end in sequence, and end the second row of lithium-ion batteries Bat 2j Detection of overheating; S2-8: Switch the input end of the first multiplexer (5011) to the third input end in sequence, and keep the third row lead terminal connected to the negative pole of the power supply (502); switch the input end of the second multiplexer (5012) from the first input end to the Nth input end in sequence, and end the lithium-ion battery Bat in the third row. 3j Whether overheating occurs; S2-9: Switch the input end of the first multiplexer (5011) to the i-th input end, and switch the input end of the second multiplexer (5012) from the 1st input end to the N-th input end, and end the lithium-ion battery Bat of the i-th row. ij Detection of overheating; S2-10: Repeat steps 2-9 until the input end of the first multiplexer (5011) is switched to the Mth input end, and the input end of the second multiplexer (5012) is switched from the 1st input end to the Nth input end, and the lithium-ion battery Bat in the Mth row is terminated. Mj Detection of whether overheating occurs; that is, complete overheating detection of the entire battery pack.

Images