Early warning methods for thermal runaway in lithium batteries, lithium batteries and electrical equipment

Abstract

This invention relates to a method for early warning of thermal runaway in lithium batteries, a lithium battery, and electrical equipment. The early warning method includes: detecting whether the pressure relief valve of the lithium battery is fully open; issuing a first-level early warning alarm when the pressure relief valve is fully open; issuing a second-level early warning alarm when the internal pressure exceeds a preset pressure threshold and the concentration exceeds a preset concentration threshold; issuing a third-level early warning alarm when either the internal pressure or the concentration exceeds a preset pressure threshold; detecting the operating temperature and operating voltage of the lithium battery when the internal pressure is less than or equal to a preset pressure threshold and the concentration is less than or equal to a preset concentration threshold; comparing the measured operating temperature and operating voltage with preset temperature thresholds and preset voltage ranges, respectively; and determining whether to issue a fourth-level early warning alarm based on the comparison results. This early warning method can issue corresponding levels of early warning alarms to users according to the severity of lithium battery thermal runaway. The method is simple, easy to operate, and has low control costs.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to a method for early warning of thermal runaway in lithium batteries, lithium batteries, and electrical equipment. Background Technology

[0002] Lithium-ion batteries (commonly known as "lithium batteries") are among the most common rechargeable batteries. They rely on the repeated insertion and extraction of lithium ions between the positive and negative electrodes to achieve repeated charging and discharging. Lithium-ion batteries have many advantages, such as high voltage, high specific energy, long cycle life, and no memory effect, and therefore they are widely used in many fields such as smartphones, laptops, electric vehicles, medical devices, and aerospace.

[0003] Lithium-ion batteries in current technology mainly consist of a battery cell and a battery management system (BMS). The battery cell typically includes a casing, positive and negative electrodes placed inside the casing, a separator between the positive and negative electrodes, and an electrolyte. During actual charging and discharging, lithium-ion batteries are prone to overheating, swelling, and even spontaneous combustion and explosion, significantly limiting their safety performance. This is due to several factors. First, if the positive electrode material (such as lithium cobalt oxide or lithium manganese oxide) of a charging lithium-ion battery is unstable, it can decompose and release oxygen at high temperatures. This causes the organic solvent in the electrolyte to react with the oxygen, generating significant heat. Second, under a certain voltage, the electrolyte itself may also react, releasing a large amount of heat. Furthermore, membrane wrinkling or damage, or metal debris connecting the positive and negative electrodes, can lead to short circuits, generating a large amount of heat in a short time. When the electrolyte boils and evaporates under heat, it produces a large amount of flammable gas. This flammable gas is easily ignited under heat, causing a sharp increase in pressure inside the sealed casing, which can lead to the lithium battery bulging or even exploding.

[0004] To enhance the safety performance of lithium batteries, an early warning method for lithium battery thermal runaway has been developed in existing technologies. For example, Chinese invention patent application CN114267150A discloses an early fire detection and warning method for lithium battery thermal runaway. This method first employs a distributed sensor deployment approach to arrange multiple sensors in the battery compartment to measure characteristic parameters of temperature, combustible gas, and smoke. Then, using the measured characteristic parameters, a multi-parameter fusion evidence theory model is used to determine the early warning of lithium battery thermal runaway and fire, providing warnings and alarms in three states: "normal," "warning," and "fire." Because this method requires deploying a large number of sensors within the limited lithium battery energy storage space, and simultaneously requires establishing and calculating a multi-parameter fusion evidence theory model for multiple parameters such as temperature, combustible gas, and smoke concentration measured by the sensors, as well as learning and analyzing the sensor data sequence using a neural recursive network method, this early warning method is overly complex and has high control costs.

[0005] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0006] To improve upon or partially address the technical problems of overly complex and costly early warning methods for lithium battery thermal runaway in existing technologies, this invention provides an early warning method for lithium battery thermal runaway. The early warning method includes:

[0007] Check whether the pressure relief valve of the lithium battery is fully open;

[0008] When the pressure relief valve is fully open, a Level 1 warning alarm is issued;

[0009] When the pressure relief valve is not fully open, the internal pressure of the lithium battery and the concentration of the released combustible gas are detected by a pressure sensor and a combustible gas concentration sensor arranged on the lithium battery, respectively.

[0010] The internal pressure and the concentration are compared with preset pressure thresholds and preset concentration thresholds, respectively.

[0011] When the internal pressure exceeds the preset pressure threshold and the concentration exceeds the preset concentration threshold, a level two early warning alarm is issued.

[0012] A level three warning alarm is issued when the internal pressure is greater than the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, or when the internal pressure is less than or equal to the preset pressure threshold and the concentration is greater than the preset concentration threshold.

[0013] When the internal pressure is less than or equal to the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, the operating temperature and operating voltage of the lithium battery are detected.

[0014] The measured operating temperature and operating voltage are compared with a preset temperature threshold and a preset voltage range, respectively.

[0015] Based on the comparison results, determine whether to issue a Level IV early warning alert.

[0016] In the lithium battery thermal runaway early warning method of this invention, the first step is to detect whether the pressure relief valve of the lithium battery is fully open. When the pressure relief valve is fully open, it indicates that the internal pressure of the lithium battery is extremely high, and the risk of spontaneous combustion or explosion is extremely high, thus issuing a "Level 1 early warning alarm". When the pressure relief valve is not fully open, the internal pressure of the lithium battery and the concentration of released combustible gas are detected by pressure sensors and combustible gas concentration sensors arranged on the lithium battery, respectively. Then, the measured internal pressure and concentration are compared with preset pressure thresholds and preset concentration thresholds, respectively. When the internal pressure is greater than the preset pressure threshold and the concentration is greater than the preset concentration threshold, it indicates that the internal pressure of the lithium battery is high and the concentration of released combustible gas is also high, and the risk of spontaneous combustion or explosion is very high, thus issuing a "Level 2 early warning alarm". When the internal pressure is greater than the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, or when the internal pressure is less than or equal to the preset pressure threshold and the concentration is greater than the preset concentration threshold, the risk of spontaneous combustion or explosion is high, thus issuing a "Level 3 early warning alarm". When the internal pressure is less than or equal to the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, the operating temperature and operating voltage of the lithium battery are detected. Next, the measured operating temperature and operating voltage are compared with preset temperature thresholds and preset voltage ranges, respectively. Finally, based on the comparison results, it is determined whether to issue a level four warning alarm. Through the above settings, the lithium battery thermal runaway warning method of the present invention can issue four corresponding levels of warning alarms to the user according to the severity of lithium battery thermal runaway. This not only ensures the safe and stable operation of the lithium battery, but also makes the warning method simple, easy to operate, and has low control costs.

[0017] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the step of "determining whether to issue a level four early warning alarm based on the comparison results" includes:

[0018] When the operating temperature exceeds the preset temperature threshold and the operating voltage exceeds the preset voltage range, a level four warning alarm is issued. When the lithium battery's operating temperature exceeds the preset temperature threshold and the operating voltage exceeds the preset voltage range, it indicates that the lithium battery is at risk of spontaneous combustion or explosion, but the risk is low; therefore, issuing a level four warning alarm is sufficient.

[0019] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the step of "determining whether to issue a level four early warning alarm based on the comparison results" includes:

[0020] When the operating temperature exceeds the preset temperature threshold or the operating voltage exceeds the preset voltage range, a level four warning alarm is issued. When the lithium battery's operating temperature exceeds the preset temperature threshold or the operating voltage exceeds the preset voltage range, it indicates a risk of spontaneous combustion or explosion, but the risk is low; therefore, issuing a level four warning alarm is sufficient.

[0021] In a preferred embodiment of the aforementioned early warning method for lithium battery thermal runaway, a microswitch matching the pressure relief valve is provided on the lithium battery to detect whether the pressure relief valve is fully open. By providing a microswitch matching the pressure relief valve on the lithium battery, the opening and closing signal of the pressure relief valve can be easily obtained, thereby detecting whether the pressure relief valve is fully open.

[0022] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the pressure relief valve is fully opened when the internal pressure is greater than the pressure relief pressure, wherein the pressure relief pressure is greater than the preset pressure threshold. Through this setting, it can be ensured that the internal pressure of the lithium battery is higher when a Level 1 early warning alarm is issued than the internal pressures when Level 2 and Level 3 early warning alarms are issued, thereby more accurately reflecting the degree of thermal runaway of the lithium battery.

[0023] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the pressure relief range is 1.8 atm-2.2 atm, and the preset pressure threshold ranges from 1.3 atm to 1.7 atm. These settings ensure that the pressure relief and preset pressure threshold have appropriate value ranges.

[0024] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the preset concentration threshold ranges from 140ppm to 160ppm. This setting allows the preset concentration threshold to have a suitable value range.

[0025] In the preferred embodiment of the above-mentioned early warning method for lithium battery thermal runaway, the first-level, second-level, third-level, and fourth-level early warning alarms are one or more of the following: information alarm, sound alarm, and light alarm. Through the above settings, the specific forms of early warning alarms can be enriched to meet the differentiated needs of different users.

[0026] To improve upon or partially resolve the technical problems of overly complex and costly early warning methods for lithium battery thermal runaway in existing technologies, this invention provides a lithium battery. This lithium battery employs any of the aforementioned early warning methods for lithium battery thermal runaway management. By adopting any of the aforementioned early warning methods for lithium battery thermal runaway, the lithium battery of this invention can conveniently and accurately issue corresponding early warning alarms to users based on the severity of thermal runaway, ensuring the safe and stable operation of the lithium battery and preventing safety accidents such as fires and explosions.

[0027] To improve or partially solve the technical problems of overly complex and costly early warning methods for lithium battery thermal runaway in existing technologies, this invention provides an electrical device. This device includes the lithium battery described above. The device can conveniently and accurately issue corresponding early warning alarms to users based on the severity of thermal runaway, thereby providing timely safety warnings and improving the safety performance of the device. Attached Figure Description

[0028] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0029] Figure 1 This is a schematic diagram of the structure of an embodiment of the lithium battery of the present invention;

[0030] Figure 2 This is a schematic diagram of an embodiment of the pressure relief valve for a lithium battery of the present invention;

[0031] Figure 3 This is a cross-sectional structural schematic diagram of an embodiment of the pressure relief valve of the lithium battery of the present invention;

[0032] Figure 4 This is a flowchart illustrating the early warning method for lithium battery thermal runaway according to the present invention.

[0033] Figure 5 This is a flowchart illustrating the first embodiment of the early warning method for thermal runaway of lithium batteries according to the present invention.

[0034] Figure 6 This is a flowchart illustrating the first embodiment of the early warning method for thermal runaway of lithium batteries according to the present invention.

[0035] List of reference numerals in the attached diagram:

[0036] 1. Protective device; 10. Outer shell; 11. Outer shell body; 111. Air inlet; 112. Decay section; 113. Connecting section; 114. Flame-retardant section; 115. Air outlet; 1151. Air outlet; 12. Inner cavity; 20. Pressure relief valve; 21. Cylinder; 22. Pressure relief core; 23. Pre-tightening elastic element; 30. Decay mechanism; 31. Feed port; 40. Flame-retardant mechanism; 41. Flame-arresting core; 50. Detection mechanism; 51. Pressure sensor; 52. Combustible gas concentration sensor; 531. Micro switch; 532. Fixing bracket; 2. Lithium battery. Detailed Implementation

[0037] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0038] It should be noted that in the description of this invention, terms such as "upper," "lower," "left," "right," "inner," and "outer," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] To improve upon or partially address the technical problems of overly complex and costly early warning methods for lithium battery thermal runaway in existing technologies, this invention provides an early warning method for lithium battery thermal runaway. This early warning method includes:

[0041] Check whether the pressure relief valve 20 of lithium battery 2 is fully open (step S1);

[0042] When the pressure relief valve 20 is fully open, a first-level warning alarm is issued (step S2);

[0043] When the pressure relief valve 20 is not fully open, the internal pressure of the lithium battery 2 and the concentration of the released combustible gas are detected by the pressure sensor 51 and the combustible gas concentration sensor 52 arranged on the lithium battery 2, respectively (step S3).

[0044] The internal pressure and concentration are compared with preset pressure thresholds and preset concentration thresholds, respectively (step S4);

[0045] When the internal pressure exceeds the preset pressure threshold and the concentration exceeds the preset concentration threshold, a level two early warning alarm is issued (step S5);

[0046] When the internal pressure is greater than the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, or when the internal pressure is less than or equal to the preset pressure threshold and the concentration is greater than the preset concentration threshold, a level three warning alarm is issued (step S6).

[0047] When the internal pressure is less than or equal to a preset pressure threshold and the concentration is less than or equal to a preset concentration threshold, the operating temperature and operating voltage of the lithium battery 2 are detected (step S7).

[0048] The measured operating temperature and operating voltage are compared with the preset temperature threshold and preset voltage range, respectively (step S8);

[0049] Based on the comparison results, determine whether to issue a Level 4 warning alert (step S9).

[0050] Figure 1 This is a schematic diagram of the structure of an embodiment of the lithium battery of the present invention; Figure 2 This is a schematic diagram of an embodiment of the pressure relief valve for a lithium battery of the present invention; Figure 3 This is a cross-sectional structural schematic diagram of an embodiment of the pressure relief valve for a lithium battery of the present invention. (See attached diagram.) Figures 1-3 As shown, the lithium battery 2 of the present invention includes a lithium battery body (not shown) and a protective device 1 disposed on the lithium battery body. The lithium battery body can be a square battery, a cylindrical battery, or a pouch battery. The protective device 1 is inserted into the lithium battery body to communicate with the interior of the lithium battery body.

[0051] like Figure 2 and Figure 3 As shown, in one or more embodiments, the protective device 1 includes components such as a housing 10, a pressure relief valve 20 arranged on the housing 10, and a detection mechanism 50 arranged in the housing 10. The housing 10 has a housing body 11. The housing body 11 can be made of a suitable metal material such as stainless steel to give it good mechanical properties. The housing body 11 forms a hollow inner cavity 12. The housing 10 has an opposing air inlet end 111 and an air outlet end 115. The air inlet end 111 is adapted to be connected to the interior of the lithium battery 2. The air outlet end 115 is provided with a generally circular air outlet 1151 to form air communication with the external environment. Along the direction from the air inlet end 111 to the air outlet end 115, the housing body 11 is sequentially divided into a corrosion section 112, a connecting section 113, and a flame-retardant section 114.

[0052] like Figure 2 and Figure 3 As shown, the pressure relief valve 20 is arranged at the air inlet 111. The pressure relief valve 20 includes a cooperating cylinder 21, a pressure relief core 22, and a pre-tightening elastic element 23. The cylinder 21 is fixed to the air inlet 111. The fixing method includes, but is not limited to, screwing, snapping, and bonding. The pressure relief core 22 is movably fixed in the cylinder 21. The two ends of the pre-tightening elastic element 23 are respectively fixed to the cylinder 21 and the pressure relief core 22. When the internal pressure of the lithium battery 2 does not exceed a predetermined value, the pre-tightening elastic element 23 can apply a pre-tightening force to the pressure relief core 22 to keep it in a "sealed position" that isolates the interior of the lithium battery 2 from the inner cavity 12 of the outer casing 10. When the internal pressure of the lithium battery 2 exceeds the predetermined value, the pressure relief core 22 will overcome the pre-tightening force of the pre-tightening elastic element 23 and move to a "pressure relief position" that connects the interior of the lithium battery 2 to the inner cavity 12 of the outer casing 10. Furthermore, when the internal pressure of the lithium battery 2 is greater than the pressure relief pressure, the distance between the pressure relief core 22 and the cylinder 21 reaches its maximum value, at which point the pressure relief valve 20 is fully opened. When the internal pressure of the lithium battery 2 gradually decreases below the predetermined value, the pressure relief core 22 is reset to the sealed position under the action of the pre-tightening elastic element 23.

[0053] like Figure 2 and Figure 3 As shown, the detection mechanism 50 includes a pressure sensor 51 and a combustible gas concentration sensor 52 arranged within the inner cavity 12. The pressure sensor 51 can detect the internal pressure of the lithium battery 2 in real time. The combustible gas concentration sensor 52 can detect the concentration of combustible gas released from the lithium battery 2 into the inner cavity 12 in real time. Combustible gases include, but are not limited to, CO, H2, CH4, etc. In one or more embodiments, the detection mechanism 50 also includes a micro switch 531 that matches the pressure relief valve 20. The micro switch 531 is fixed on a fixed bracket 532, which is fixed in the inner cavity 12. When the internal pressure of the lithium battery 2 exceeds a predetermined value and is greater than the pressure relief pressure, the pressure relief core 22 is pushed by the gas inside the lithium battery 2 and comes into contact with the micro switch 531, causing the micro switch 531 to be opened (or closed). When the internal pressure of the lithium battery 2 gradually decreases, the pressure relief core 22 gradually resets under the action of the pre-tightening elastic element 23, and the pressure relief core 22 disengages from the micro switch 531, causing the micro switch 531 to be closed (or opened). By using the microswitch 531, it is easy to determine whether the pressure relief valve 20 is fully open.

[0054] like Figure 2 and Figure 3As shown, in one or more embodiments, the protective device 1 further includes a degradation mechanism 30. The degradation mechanism 30 includes components such as a feed port 31, a reservoir, and a feeder (not shown). The reservoir is configured to store a degradation agent. The degradation agent includes, but is not limited to, halogenated flame retardants, organophosphorus flame retardants, and organosilicon flame retardants. The feed port 31 is formed in the degradation section 112 of the outer casing 10 and communicates with the reservoir. The feeder is configured to deliver the degradation agent from the reservoir into the inner cavity 12 through the feed port 31, causing the combustible gas in the inner cavity 12 to mix with the degradation agent, thereby reducing the probability of combustion of the combustible gas.

[0055] like Figure 2 and Figure 3 As shown, in one or more embodiments, the protective device 1 further includes a flame-retardant mechanism 40. The flame-retardant mechanism 40 includes two interconnected flame-retardant cores 41. These two flame-retardant cores 41 are placed in the flame-retardant section 114 near the gas outlet 115, so that even if the combustible gas in the inner cavity 12 ignites, the open flame will be quickly extinguished by the blocking effect of the flame-retardant cores 41, thereby preventing the open flame from spreading within the inner cavity 12. The flame-retardant cores 41 can be made of stainless steel or other suitable materials. Alternatively, the number of flame-retardant cores 41 can also be set to more or less than two, such as one, three, etc.

[0056] The following describes in detail the early warning method for thermal runaway of the lithium battery 2 of the present invention, with reference to the embodiments of the lithium battery 2 described above. It should be noted that this early warning method can be implemented not only in the lithium battery 2 described in any of the above embodiments, but also in other suitable rechargeable batteries.

[0057] Figure 4 This is a flowchart illustrating the early warning method for lithium battery thermal runaway according to the present invention. Figure 4As shown, in one or more embodiments, after the early warning method for thermal runaway of the lithium battery 2 of the present invention starts, step S1 is first executed, that is, detecting whether the pressure relief valve 20 of the lithium battery 2 is fully open. When the pressure relief valve 20 is fully open, a first-level early warning alarm is issued (step S2). When the pressure relief valve 20 is not fully open, the internal pressure of the lithium battery 2 and the concentration of the released combustible gas are detected by the pressure sensor 51 and the combustible gas concentration sensor 52 arranged on the lithium battery 2, respectively (step S3). Next, the early warning method proceeds to step S4, comparing the internal pressure and concentration with preset pressure thresholds and preset concentration thresholds, respectively. When the internal pressure is greater than the preset pressure threshold and the concentration is greater than the preset concentration threshold, a second-level early warning alarm is issued (step S5). When the internal pressure is greater than the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, or when the internal pressure is less than or equal to the preset pressure threshold and the concentration is greater than the preset concentration threshold, a third-level early warning alarm is issued (step S6). When the internal pressure is less than or equal to the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, the operating temperature and operating voltage of the lithium battery 2 are detected (step S7). Then, the measured operating temperature and operating voltage are compared with the preset temperature threshold and preset voltage range, respectively (step S8). Finally, based on the comparison results, it is determined whether to issue a level four warning alarm (step S9).

[0058] Figure 5 This is a flowchart illustrating the first embodiment of the early warning method for lithium battery thermal runaway of the present invention. Figure 5 As shown, in one or more embodiments, after the early warning method for thermal runaway of the lithium battery 2 of the present invention begins, step S10 is first executed, that is, determining whether the pressure relief valve 20 of the lithium battery 2 is fully open. In one or more embodiments, whether the pressure relief valve 20 is fully open is detected by a microswitch 531 matched with the pressure relief valve 20. When the internal pressure of the lithium battery 2 is greater than the pressure relief pressure, the pressure relief valve 20 is fully open. In one or more embodiments, the pressure relief pressure ranges from 1.8 atm to 2.2 atm (i.e., standard atmospheric pressure). Alternatively, the pressure relief pressure can also be set to other suitable values. When the determination result is yes, it indicates that the internal pressure of the lithium battery 2 is extremely high, and the risk of spontaneous combustion or explosion of the lithium battery 2 is extremely high. Therefore, step S20 is executed, that is, a first-level early warning alarm is issued. When step S20 is completed, the early warning method ends.

[0059] See also Figure 5In step S10, if the judgment result is negative, step S30 is executed, where the internal pressure of the lithium battery 2 and the concentration of released combustible gas are detected by the pressure sensor 51 and the combustible gas concentration sensor 52 arranged on the lithium battery 2, respectively. Next, step S41 is executed to determine whether the internal pressure is greater than a preset pressure threshold. In one or more embodiments, the preset pressure threshold ranges from 1.3 atm to 1.7 atm. Alternatively, the preset pressure threshold can be set to other suitable values. If the judgment result is positive, step S42 is executed, i.e., determining whether the concentration is greater than a preset concentration threshold. In one or more embodiments, the preset concentration threshold ranges from 140 ppm to 160 ppm (i.e., parts per million). If the judgment result is positive, it indicates that the internal pressure of the lithium battery 2 is high and the concentration of released combustible gas is also high, and the risk of spontaneous combustion or explosion of the lithium battery 2 is very high. Therefore, step S50 is executed, i.e., a secondary warning alarm is issued. The warning method ends after step S50 is completed.

[0060] See also Figure 5 When executing step S42, if the judgment result is negative, it indicates that although the concentration of flammable gas released by lithium battery 2 is relatively small, the internal pressure of lithium battery 2 is high, and the risk of spontaneous combustion or explosion of lithium battery 2 is high. Therefore, step S60 is executed, that is, a level three warning alarm is issued. When step S60 is completed, the warning method ends.

[0061] See also Figure 5 When performing step S41, if the judgment result is negative, proceed to step S43, which determines whether the concentration exceeds a preset concentration threshold. If the judgment result is positive, it indicates that although the internal pressure of lithium battery 2 is not high, the concentration of released flammable gas is relatively high, and the risk of spontaneous combustion or explosion of lithium battery 2 is high. Therefore, proceed to step S60, which issues a level three warning alarm. After step S60 is completed, the warning method ends.

[0062] See also Figure 5 When executing step S43, if the judgment result is negative, step S70 is executed, which involves detecting the operating temperature and operating voltage of the lithium battery 2. The operating temperature and operating voltage of the lithium battery 2 can be measured by temperature sensors and voltage sensors arranged on the lithium battery body. In one or more embodiments, after step S70 is completed, the warning method proceeds to step S81, which involves determining whether the operating temperature is greater than a preset temperature threshold. The specific value of the preset temperature threshold can be adjusted according to actual needs. If the judgment result is negative, step S91 is executed, and no warning alarm is issued. After step S91 is completed, the warning method ends.

[0063] See also Figure 5When executing step S81, if the judgment result is yes, proceed to step S82, which determines whether the operating voltage exceeds the preset voltage range. The specific value range of the preset voltage range can also be adjusted according to actual needs. If the operating voltage exceeds the preset voltage range, it indicates that the operating voltage is too high or too low. If the judgment result is no, proceed to step S91, and no warning alarm is issued. The warning method ends after step S91 is completed. If the judgment result is yes, it indicates that the operating temperature of lithium battery 2 is higher than the preset temperature threshold and the operating voltage exceeds the preset voltage range (too high or too low), and lithium battery 2 is at risk of spontaneous combustion or explosion. Therefore, proceed to step S92, and issue a level four warning alarm. The warning method ends after step S92 is completed. The alarm methods for level one, level two, level three, and level four warning alarms include, but are not limited to, information alarms, sound alarms, and light alarms. For example, level one, level two, level three, and level four warning alarms correspond to red, orange, yellow, and green alarm lights, respectively.

[0064] Figure 6 This is a flowchart illustrating the second embodiment of the early warning method for lithium battery thermal runaway of the present invention. Figure 6 As shown, in one or more embodiments, after executing step S70, the early warning method for thermal runaway of the lithium battery 2 of the present invention executes step S81, that is, determining whether the operating temperature is greater than a preset temperature threshold. If the determination result is yes, step S92 is executed directly, that is, a level four early warning alarm is issued. If the determination result is no, the early warning method proceeds to step S82, determining whether the operating voltage exceeds a preset voltage range. If the determination result is yes, step S92 is executed directly, that is, a level four early warning alarm is issued. When step S92 is completed, the early warning method ends.

[0065] See also Figure 6 When executing step S82, if the judgment result is negative, it means that the operating temperature and operating voltage of lithium battery 2 have not exceeded the preset values, and lithium battery 2 is working normally. Therefore, step S91 is executed, and no warning alarm is issued. When step S91 is completed, the warning method ends.

[0066] It should be noted that the parts not mentioned in the second embodiment can be configured the same as in the first embodiment, and will not be repeated here.

[0067] In one or more embodiments, the present invention also provides an electrical device (not shown in the figures). This electrical device includes the lithium battery 2 described in any of the above embodiments. The electrical device may be, but is not limited to, an electric vehicle, an energy storage device, a portable computer, a lamp, etc.

[0068] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for early warning of thermal runaway in lithium batteries, characterized in that, The early warning method includes: Check whether the pressure relief valve of the lithium battery is fully open; When the pressure relief valve is fully open, a Level 1 warning alarm is issued; When the pressure relief valve is not fully open, the internal pressure of the lithium battery and the concentration of the released combustible gas are detected by a pressure sensor and a combustible gas concentration sensor arranged on the lithium battery, respectively. The internal pressure and the concentration are compared with preset pressure thresholds and preset concentration thresholds, respectively. When the internal pressure exceeds the preset pressure threshold and the concentration exceeds the preset concentration threshold, a level two early warning alarm is issued. A level three warning alarm is issued when the internal pressure is greater than the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, or when the internal pressure is less than or equal to the preset pressure threshold and the concentration is greater than the preset concentration threshold. When the internal pressure is less than or equal to the preset pressure threshold and the concentration is less than or equal to the preset concentration threshold, the operating temperature and operating voltage of the lithium battery are detected. The measured operating temperature and operating voltage are compared with a preset temperature threshold and a preset voltage range, respectively. Based on the comparison results, determine whether to issue a Level IV early warning alert.

2. The early warning method for thermal runaway of lithium batteries according to claim 1, characterized in that, The step of "determining whether to issue a Level IV early warning alert based on the comparison results" includes: When the operating temperature exceeds the preset temperature threshold and the operating voltage exceeds the preset voltage range, the fourth-level warning alarm is issued.

3. The early warning method for thermal runaway of lithium batteries according to claim 1, characterized in that, The step of "determining whether to issue a Level IV early warning alert based on the comparison results" includes: When the operating temperature exceeds the preset temperature threshold or the operating voltage exceeds the preset voltage range, the fourth-level warning alarm is issued.

4. The early warning method for thermal runaway of lithium batteries according to claim 1, characterized in that, A microswitch is provided on the lithium battery to match the pressure relief valve, so as to detect whether the pressure relief valve is fully open.

5. The early warning method for thermal runaway of lithium batteries according to claim 1, characterized in that, When the internal pressure is greater than the pressure relief pressure, the pressure relief valve is fully opened, wherein the pressure relief pressure is greater than the preset pressure threshold.

6. The early warning method for thermal runaway of a lithium battery according to claim 5, characterized in that, The pressure relief range is 1.8 atm to 2.2 atm, and the preset pressure threshold range is 1.3 atm to 1.7 atm.

7. The early warning method for thermal runaway of a lithium battery according to claim 1, characterized in that, The preset concentration threshold ranges from 140ppm to 160ppm.

8. The early warning method for thermal runaway of a lithium battery according to claim 1, characterized in that, The first-level warning alarm, the second-level warning alarm, the third-level warning alarm, and the fourth-level warning alarm are triggered by one or more of the following methods: information alarm, sound alarm, and light alarm.

9. A lithium battery, characterized in that, The lithium battery is managed for thermal runaway using the early warning method for thermal runaway of lithium batteries according to any one of claims 1-8.

10. An electrical appliance, characterized in that, The electrical equipment includes the lithium battery according to claim 9.

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