A battery and battery pack

Abstract

The application discloses a battery and a battery pack, the battery comprising: a shell having an inner wall, the inner wall being provided with a phase change material coating; a cover plate provided with an explosion-proof valve; and a pole piece, comprising: a positive current collector divided into a first zone and a second zone arranged in sequence, and a negative current collector divided into a third zone and a fourth zone arranged in sequence; a positive active layer arranged in the first zone, and a negative active layer arranged in the third zone; a thermistor layer directly contacting the second zone and the fourth zone respectively; and a diaphragm arranged between the first zone and the third zone; wherein the diaphragm has a melting temperature, the thermistor layer has a temperature threshold value, the temperature threshold value is less than the melting temperature, when the temperature of the battery reaches the temperature threshold value, the thermistor layer changes from insulation to making the second zone and the fourth zone conductive to form a short circuit, the phase change material coating receives heat from the short circuit to release gas, and the explosion-proof valve is opened to discharge the gas. The explosion-proof valve can be opened in advance before thermal runaway, the phenomenon of valve opening and thermal runaway is effectively avoided, and the risk caused by diaphragm melting is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery and a battery pack. Background Technology

[0002] Cylindrical batteries are widely used in electric vehicles, energy storage systems, and other fields due to their high energy density and excellent electrochemical performance. With increasingly stringent safety requirements, existing cylindrical batteries typically employ a thermoelectric separation design, where the electrode terminals and explosion-proof valves are located at opposite ends of the battery cover. This design aims to ensure battery thermal safety by allowing directional venting and pressure relief via the explosion-proof valve in the event of thermal runaway, preventing high-temperature, high-pressure gases from directly damaging the electrical connection structure.

[0003] In existing technologies, explosion-proof valves typically operate based on a pressure threshold triggering mechanism. Specifically, when a battery is subjected to extreme abuse conditions such as overcharging, overheating, or internal short circuits, a violent electrochemical reaction occurs inside the battery, generating a large amount of gas and causing a rapid increase in internal pressure. When the internal pressure rises to a set threshold, the explosion-proof valve opens, carrying away the high-temperature gas and heat from inside the battery to reduce internal pressure and prevent the battery from exploding or burning.

[0004] However, taking ternary cylindrical batteries as an example, due to their relatively reactive chemical properties, the gas production rate during thermal runaway is extremely fast. The rapid increase in internal gas pressure often occurs almost simultaneously with the onset of thermal runaway. In other words, when thermal runaway occurs, the internal gas pressure instantly reaches a threshold and forces open the explosion-proof valve to release pressure, exhibiting a phenomenon of "valve opening leads to runaway." Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses a battery and a battery pack.

[0006] In a first aspect, embodiments of the present invention provide a battery, comprising:

[0007] A housing having an opening and an inner wall, the inner wall being coated with a phase change material;

[0008] A cover plate for sealing the opening, the cover plate being equipped with an explosion-proof valve;

[0009] An electrode, disposed within the housing, includes:

[0010] The current collector includes a positive current collector and a negative current collector. The positive current collector is divided into a first region and a second region arranged sequentially along the length direction of the electrode sheet. The negative current collector is divided into a third region and a fourth region arranged sequentially along the length direction. The first region and the third region are arranged opposite to each other along the thickness direction of the electrode sheet. The second region and the fourth region are arranged opposite to each other along the thickness direction.

[0011] An active layer includes a positive active layer and a negative active layer, wherein the positive active layer is disposed in the first region and the negative active layer is disposed in the third region;

[0012] A thermistor layer is disposed between the second region and the fourth region, and is in direct contact with the second region and the fourth region respectively;

[0013] A diaphragm is disposed between the first region and the third region;

[0014] The diaphragm has a melting temperature, and the thermistor layer has a temperature threshold, which is less than the melting temperature. When the temperature of the battery reaches the temperature threshold, the thermistor layer changes from insulation to short-circuiting the second region and the fourth region. The phase change material coating can receive the heat generated by the short circuit to release gas, thereby opening the explosion-proof valve to release the gas.

[0015] By adopting the above technical solution, a controllable short circuit can be actively triggered before thermal runaway, and the explosion-proof valve can be opened in advance to release gas and heat. This effectively avoids the phenomenon of runaway upon valve opening and reduces the risk of malignant internal short circuit caused by diaphragm melting. At the same time, the short circuit does not damage the electrochemical working area of ​​the battery, and the battery has good anti-false triggering capability, thus improving the safety and stability of the battery.

[0016] Further, along the width direction of the electrode, the second region is divided into a first coated region and a first uncoated region arranged sequentially, and the fourth region is divided into a second coated region and a second uncoated region arranged sequentially; along the thickness direction, the first coated region and the second coated region are arranged opposite to each other, and the first uncoated region and the second uncoated region are arranged opposite to each other; the thermistor layer is disposed between the first coated region and the second coated region, and the diaphragm is disposed between the first uncoated region and the second uncoated region.

[0017] Furthermore, along the width direction, the ratio of the width of the thermistor layer to the width of the electrode is 0.15 to 0.20;

[0018] And / or, along the length direction, the ratio of the length of the thermistor layer to the length of the electrode is 0.2~2%.

[0019] Furthermore, along the thickness direction, the thickness of the thermistor layer matches the thickness of the active layer.

[0020] Furthermore, the battery also includes a tab, which is disposed at one end of the electrode along the width direction of the electrode sheet;

[0021] The thermistor layer includes a first thermistor region, a second thermistor region, and a third thermistor region arranged sequentially along the direction from the tab toward the electrode. The first thermistor region has a first temperature threshold, the second thermistor region has a second temperature threshold, and the third thermistor region has a third temperature threshold. The first temperature threshold is less than the second temperature threshold, and the first temperature threshold is less than the third temperature threshold.

[0022] Furthermore, the first temperature threshold < the third temperature threshold < the second temperature threshold.

[0023] Furthermore, the first temperature threshold is 70~80℃, the second temperature threshold is 120~180℃, and the third temperature threshold is 90~105℃.

[0024] Furthermore, the thermistor layer comprises NTC material, binder, and ceramic powder.

[0025] Furthermore, based on the mass of the thermistor layer as 100%, the thermistor layer comprises 80-96% NTC material, 2-10% binder, and 2-10% ceramic powder.

[0026] Furthermore, it includes a battery cell, which includes the electrode and the separator, and the battery cell is a wound core or a stacked core.

[0027] In a second aspect, embodiments of the present invention provide a battery pack including the battery as described in any embodiment of the first aspect.

[0028] By adopting the above technical solution, a controllable short circuit can be actively triggered in the battery before thermal runaway, so as to open the battery's explosion-proof valve in advance to release gas and heat, thereby suppressing the violent outbreak of thermal runaway from the source of the battery, delaying the process of thermal runaway, reducing the severity of thermal runaway of a single battery, and reducing the probability of thermal runaway of a single battery spreading to adjacent batteries, thereby improving the safety and stability of the battery pack. Attached Figure Description

[0029] Figure 1 A top view of the housing structure is shown in a specific embodiment of the present invention;

[0030] Figure 2 Show Figure 1 A schematic diagram of the cross-sectional structure along aa;

[0031] Figure 3 A schematic diagram of the battery cell structure is shown in a specific embodiment of the present invention;

[0032] Figure 4 This diagram illustrates the structure of the electrode sheet in a specific embodiment of the present invention.

[0033] Figure 5 A schematic diagram of the structure of the thermistor layer in a specific embodiment of the present invention is shown.

[0034] (Symbol Explanation)

[0035] 1. Shell; 11. Phase change material coating; 2. Electrode; 21. Current collector; 211. Positive current collector; 2111. First region; 2112. Second region; 21121. First coated region; 21122. First uncoated region; 212. Negative current collector; 2121. Third region; 2122. Fourth region; 21221. Second coated region; 21222. Second uncoated region; 22. Active layer; 221. Positive active layer; 222. Negative active layer; 23. Thermistor layer; 231. First thermistor region; 232. Second thermistor region; 233. Third thermistor region; 3. Separator;

[0036] x. Length direction, y. Width direction, y1. Direction of the tab toward the electrode, z. Thickness direction. Detailed Implementation

[0037] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0038] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0039] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0040] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0042] In this invention, the term "ternary cylindrical battery" refers to one type of cylindrical battery, and "ternary" means that the positive electrode material of the cylindrical battery contains three metallic elements.

[0043] Firstly, reference Figures 1-5 As shown, an embodiment of the present invention provides a battery, which includes a casing 1, a cover plate (not shown), and a battery cell. The casing 1 has an opening and an inner wall, and the inner wall is provided with a phase change material coating 11, which can absorb heat and release gas. The cover plate is used to seal the opening and is provided with an explosion-proof valve. The battery cell is housed inside the casing 1 through the opening, that is, the battery cell is disposed inside the casing 1.

[0044] The battery cell includes electrode 2 and separator 3, and the battery cell is a wound core (e.g. Figure 3 (As shown), or the battery cell is a stacked core. The electrode 2 includes a current collector 21, an active layer 22, and a thermistor layer 23, as detailed below:

[0045] Current collector 21 includes a positive current collector 211 and a negative current collector 212, wherein the positive current collector 211 is along the length direction of the electrode (e.g., ...). Figure 4 The direction shown (x) is divided into a first region 2111 and a second region 2112 arranged sequentially. The negative electrode current collector 212 is divided into a third region 2121 and a fourth region 2122 arranged sequentially along its length. The first region 2111 and the third region 2121 are arranged along the thickness direction of the electrode sheet (e.g., along the thickness direction of the electrode sheet). Figure 3 The second zone 2112 and the fourth zone 2122 are set relative to each other along the thickness direction (as shown in z).

[0046] The active layer 22 includes a positive active layer 221 and a negative active layer 222. The positive active layer 221 is disposed in the first region 2111, and the negative active layer 222 is disposed in the third region 2121.

[0047] The thermistor layer 23 is disposed between the second region 2112 and the fourth region 2122, and is in direct contact with the second region 2112 and the fourth region 2122, respectively. That is, the thermistor layer 23 is disposed between the positive current collector 211 and the negative current collector 212, and is in direct contact with one end of the positive current collector 211 and one end of the negative current collector 212, respectively. One end of the positive current collector 211 and one end of the negative current collector 212 are arranged opposite to each other along the thickness direction.

[0048] The separator 3 is disposed between the first region 2111 and the third region 2121, that is, the separator 3 is disposed between the positive electrode active layer 221 and the negative electrode active layer 222.

[0049] Among them, the separator 3 has a melting temperature, and the thermistor layer 23 has a temperature threshold. The temperature threshold is less than the melting temperature. When the temperature of the battery reaches the temperature threshold, the thermistor layer 23 changes from insulation to making the second region 2112 and the fourth region 2122 conduct to form a short circuit. That is, the positive current collector 211 and the negative current collector 212 conduct to form a short circuit. The phase change material coating 11 can receive the heat generated by the short circuit to release gas, thereby opening the explosion-proof valve to vent the gas.

[0050] Specifically, the thermistor layer 23 is a negative resistance type temperature-varying phase-change thermistor material, and its resistance decreases as temperature increases. Under normal battery operating temperature, the thermistor layer 23 has high resistance and acts as an insulator. As the battery temperature continues to rise, its resistance gradually decreases, and when the temperature reaches its temperature threshold (i.e., critical temperature), it changes from an insulator to a conductor. The melting temperature of the separator typically corresponds to the thermal runaway temperature of the battery when the explosion-proof valve opens. The temperature threshold is lower than the melting temperature, meaning it is lower than the battery's thermal runaway temperature. In other words, the temperature threshold is determined based on the battery's thermal runaway temperature.

[0051] In the above embodiment, by setting the temperature threshold of the thermistor layer 23 to be lower than the melting temperature of the separator 3, that is, before the battery temperature reaches the thermal runaway temperature, the thermistor layer 23 can be transformed from an insulator to a conductor, making the positive current collector 211 and the negative current collector 212 conductive, thus actively triggering a controllable short circuit in the battery. The heat generated by the short circuit is transferred to the phase change material coating 11 located in the casing 1, triggering it to release gas to open the explosion-proof valve in advance.

[0052] In other words, before the separator 3 melts, the battery's state of charge is reduced through an internal short-circuit current loop. Simultaneously, the short circuit triggers the phase change material coating 11 to release gas, prematurely opening the explosion-proof valve and allowing the heat and gas release channels to open earlier. This not only effectively avoids the phenomenon of loss of control upon valve opening but also promptly removes high-temperature gas and heat from inside the battery. This helps reduce the risk of a large-area malignant internal short circuit caused by the melting of separator 3, thereby suppressing the occurrence and spread of battery thermal runaway and improving the battery's safety and stability.

[0053] Meanwhile, since the thermistor layer 23 is only disposed in the non-active region (i.e., the second region 2112 and the fourth region 2122) at one end of the electrode 2, and the non-active region (i.e., the first region 2111 and the third region 2121 where electrochemical operation occurs) separates the electrochemical working region from the safety triggering region, the resulting area is a local micro short circuit rather than a malignant internal short circuit. This provides sufficient heat to trigger the safety mechanism without causing irreversible damage to the battery's electrochemical working region.

[0054] In addition, the thermistor layer 23 exhibits a high-resistance insulating state at the normal operating temperature of the battery, which does not affect the normal charging and discharging performance of the battery. It only achieves conduction when the battery temperature reaches the temperature threshold and the resistance drops sharply, thus having good anti-false triggering capability.

[0055] By adopting the above technical solution, a controllable short circuit can be actively triggered before thermal runaway, and the explosion-proof valve can be opened in advance to release gas and heat, effectively avoiding the phenomenon of runaway upon valve opening and reducing the risk of malignant internal short circuit caused by the melting of the separator 3. At the same time, the short circuit does not damage the electrochemical working area of ​​the battery, and the battery has good anti-false triggering capability, improving the safety and stability of the battery.

[0056] The internal pressure of the battery acts not only on the explosion-proof valve but also on the electrode terminals. If the pressure is too high, there is a risk of the electrode terminals being forced open (i.e., erupting). Once the electrode terminals are forced open, the battery's thermoelectric separation function completely fails, leading to more serious thermal runaway consequences such as fire, explosion, and heat propagation.

[0057] Therefore, in one embodiment, the temperature threshold is lower than the melting temperature, and the difference between the temperature threshold and the melting temperature is 10~70℃. By limiting the above temperature difference range, the short-circuit response time can be adjusted, allowing the explosion-proof valve to open earlier within a suitable time window. This not only enables the orderly discharge of high-temperature and high-pressure gases from the interior, effectively suppressing the gas pressure inside the casing 1 below the critical value at which the electrode terminals are blown open, but also avoids premature triggering. This prevents more serious thermal runaway consequences such as fire, explosion, and thermal propagation caused by the opening of the electrode terminals, while improving the resistance to false triggering within the normal operating range of the battery. Further, the difference between the temperature threshold and the melting temperature is 10~30℃, 30~50℃, or 50~70℃.

[0058] In another embodiment, reference Figure 3 and Figure 4 As shown, along the width direction of the electrode (e.g.) Figure 4 As shown in the direction y), the second region 2112 is divided into a first coated region 21121 and a first uncoated region 21122 arranged sequentially, and the fourth region 2122 is divided into a second coated region 21221 and a second uncoated region 21222 arranged sequentially. Along the thickness direction, the first coated region 21121 and the second coated region 21221 are arranged opposite to each other, and the first uncoated region 21122 and the second uncoated region 21222 are arranged opposite to each other. A thermistor layer 23 is disposed between the first coated region 21121 and the second coated region 21221, and a diaphragm 3 is disposed between the first uncoated region 21122 and the second uncoated region 21222.

[0059] In the above embodiments, on the one hand, the conductive cross-sectional area of ​​the short-circuit current is determined by the area of ​​the thermistor layer 23. By dividing the second region 2112 and the fourth region 2122 into coated and uncoated regions respectively, that is, by further adjusting the area ratio of the thermistor layer 23, the magnitude of the short-circuit current and the heating power can be conveniently controlled. This ensures the heat required to trigger the safety mechanism while avoiding the instantaneous energy burst caused by a large-area short circuit, thereby ensuring that the explosion-proof valve opens in advance while preventing the electrode terminals from spewing out. On the other hand, a diaphragm is set in the uncoated region (i.e., between the first uncoated region 21122 and the second uncoated region 21222). The insulating properties of the diaphragm 3 are effectively utilized to reduce the possibility of accidental contact micro-short circuits, self-discharge, and lifespan decay of the second region 2112 and the fourth region 2122 in the non-triggered state.

[0060] Furthermore, along the width direction, the ratio of the width of the thermistor layer 23 to the width of the electrode 2 is 0.15 to 0.20. Even further, along the length direction, the ratio of the length of the thermistor layer 23 to the length of the electrode 2 is 0.2% to 2%.

[0061] Thus, by adjusting the area of ​​the thermistor layer 23 in the width or length direction, on the one hand, a reliable and effective short circuit can be formed when triggered, generating sufficient heat to drive the explosion-proof valve to open while avoiding the electrode terminals from spewing out; on the other hand, the area of ​​the active layer 22 is maximized to ensure the volumetric energy density and charge / discharge capacity of the battery.

[0062] In this embodiment of the invention, the thickness of the thermistor layer 23 matches the thickness of the active layer 22 along the thickness direction. This helps to ensure the flatness and structural consistency of the electrode surface 2, and ensures tight and reliable surface contact between the current collector 21 and the thermistor layer 23. This, in turn, ensures smooth conduction of the short-circuit current loop when the battery temperature reaches the temperature threshold, improving the trigger sensitivity and stability of the safety mechanism. Here, "matching" can be understood as the thermistor layer 23 being equal to, consistent with, or within the allowable range of process errors as the thickness of the active layer 22 is.

[0063] In an embodiment of the present invention, the battery further includes a tab (not shown), which is disposed at one end of the electrode 2 along the width direction of the electrode sheet, and the battery cell is composed of the tab, the electrode sheet 2 and the separator 3.

[0064] refer to Figures 3-5 As shown, the thermistor layer 23 includes a direction along the tab toward the electrode (e.g., ...). Figure 4 and Figure 5 The first thermistor region 231, the second thermistor region 232, and the third thermistor region 233 are arranged sequentially in the direction y1 shown. The first thermistor region 231 has a first temperature threshold, the second thermistor region 232 has a second temperature threshold, and the third thermistor region 233 has a third temperature threshold. The first temperature threshold is less than the second temperature threshold, and the first temperature threshold is less than the third temperature threshold.

[0065] In the above embodiment, the thermistor layer 23 is divided into three regions with different temperature thresholds, and the first thermistor region 231 with the lowest temperature threshold is located closest to the tab. This is because the tab is the region in the battery that heats up earliest and has the highest temperature. By placing the first thermistor region 231 with the lowest temperature threshold closest to the tab, it is ensured that it is triggered and turned on first, and can respond to changes in battery temperature in a timely manner, thereby greatly shortening the response time and achieving rapid "point-to-point" intervention. At the same time, the second thermistor region 232 and the third thermistor region 233, which have higher temperature thresholds along the direction away from the tab, not only conform to the law of gradual conduction of cell temperature from the tab to the electrode 2, avoiding unnecessary false triggering, but also achieve graded response, improving the accuracy and adaptability of the safety response.

[0066] Furthermore, the first temperature threshold < the third temperature threshold < the second temperature threshold. By setting the lowest temperature threshold in the first thermistor region 231, it is ensured that the safety mechanism can be triggered immediately once the tab, which is the main heat source, heats up, achieving precise blocking at the source. Setting the temperature threshold of the second thermistor region 232, located in the middle, to be the highest of the three can effectively prevent continuous false triggering of the safety mechanism due to local overheating of the tab or normal heat conduction, avoiding premature short circuits in the middle area under unnecessary circumstances, thereby ensuring the controllability of the battery when dealing with local faults. The temperature threshold of the third thermistor region 233, which is far from the tab, is between the first and second temperature thresholds, providing timely and effective protection and avoiding failure to respond in time due to heat diffusion loss and its distance from the tab, thereby greatly improving the reliability and anti-interference capability of the safety protection mechanism.

[0067] Furthermore, the first temperature threshold is greater than the normal operating temperature of the battery.

[0068] For example, the first temperature threshold is 70~80℃, the second temperature threshold is 120~180℃, and the third temperature threshold is 90~105℃.

[0069] In this example, the first temperature threshold of the first thermistor region 231, located near the tab, is set to 70-80°C. This range is slightly higher than the normal operating temperature of the battery but lower than the thermal runaway temperature, enabling highly sensitive monitoring of the tab, the main heat source. Once an abnormal temperature rise occurs in the tab area, this region can respond immediately and trigger protection in a timely manner, achieving early detection and early intervention to block the source. The second temperature threshold of the second thermistor region 232, located in the middle, is set to 120-180°C, effectively avoiding the risk of false triggering due to heat conduction from the adjacent tab. This setting avoids damage to the electrode structure due to premature short circuits and provides reliable protection as a "last line of defense" under extreme conditions. Furthermore, the third temperature threshold of the third thermistor region 233, located far from the tab, is set to 90-105°C, which helps avoid response lag caused by heat conduction attenuation due to its distance from the main heat source. This threshold range ensures a timely and effective response when heat spreads to the area, preventing heat propagation due to response blind spots, while also avoiding a threshold that is too low and could affect the stability of the battery's daily operation.

[0070] In this embodiment of the invention, the thermistor layer 23 comprises NTC material, binder, and ceramic powder. By utilizing the high temperature sensitivity of the NTC material's resistance change rate, the accuracy and sensitivity of the thermistor layer 23's transition from insulator to conductor as the battery temperature rises to a temperature threshold are improved. Introducing ceramic powder dilutes the volume fraction of the NTC material. On one hand, the electrical insulation properties of the ceramic powder allow the resistance of the thermistor layer 23 to be controlled to a more stable high resistance range at the battery's normal operating temperature, effectively suppressing the impact of leakage current on the battery's self-discharge rate. On the other hand, the high thermal conductivity of the ceramic powder allows for a more sensitive response to and sensing of battery temperature changes. Simultaneously, it can dissipate the Joule heat generated by the NTC material during a short circuit to the phase change material coating 11, preventing heat accumulation that could lead to irreversible resistance drift or decomposition failure of the NTC material due to overheating. Furthermore, the introduction of a binder firmly adheres the NTC material and ceramic powder to the surface of the current collector 21, ensuring the temperature resistance and structural stability of the thermistor layer 23 and preventing cracking, detachment, or delamination under conditions such as battery charge-discharge cycles, mechanical vibration, and temperature fluctuations. In addition, the presence of ceramic powder reduces the conductivity probability of the NTC material at the normal operating temperature of the battery, thus eliminating the risk of electrochemical corrosion caused by leakage current for the binder.

[0071] Furthermore, taking the mass of the thermistor layer 23 as 100%, the thermistor layer 23 comprises 80-96% NTC material, 2-10% binder, and 2-10% ceramic powder. This mass ratio of the three components achieves a balance between the conductivity, temperature sensitivity, and mechanical stability of the thermistor layer 23.

[0072] In the above embodiments, the resistance of the thermistor layer 23 is >10MΩ at the normal operating temperature of the battery (e.g. -20~60℃), and it acts as an insulator. Only when the battery temperature reaches the temperature threshold does the thermistor layer 23 change from an insulator to a conductor, so as to achieve zero interference and precise protection during normal battery operation.

[0073] In a second aspect, embodiments of the present invention provide a battery pack including the battery as described in any embodiment of the first aspect.

[0074] By adopting the above technical solution, a controllable short circuit can be actively triggered in the battery before thermal runaway, so as to open the battery's explosion-proof valve in advance to release gas and heat, thereby suppressing the violent outbreak of thermal runaway from the source of the battery, delaying the process of thermal runaway, reducing the severity of thermal runaway of a single battery, and reducing the probability of thermal runaway of a single battery spreading to adjacent batteries, thereby improving the safety and stability of the battery pack.

[0075] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A battery, characterized in that, include: A housing having an opening and an inner wall, the inner wall being coated with a phase change material; A cover plate for sealing the opening, the cover plate being equipped with an explosion-proof valve; An electrode, disposed within the housing, includes: The current collector includes a positive current collector and a negative current collector. The positive current collector is divided into a first region and a second region arranged sequentially along the length direction of the electrode sheet. The negative current collector is divided into a third region and a fourth region arranged sequentially along the length direction. The first region and the third region are arranged opposite to each other along the thickness direction of the electrode sheet. The second region and the fourth region are arranged opposite to each other along the thickness direction. An active layer includes a positive active layer and a negative active layer, wherein the positive active layer is disposed in the first region and the negative active layer is disposed in the third region; A thermistor layer is disposed between the second region and the fourth region, and is in direct contact with the second region and the fourth region respectively; A diaphragm is disposed between the first region and the third region; The diaphragm has a melting temperature, and the thermistor layer has a temperature threshold, which is less than the melting temperature. When the temperature of the battery reaches the temperature threshold, the thermistor layer changes from insulation to short-circuiting the second region and the fourth region. The phase change material coating can receive the heat generated by the short circuit to release gas, thereby opening the explosion-proof valve to release the gas.

2. The battery as described in claim 1, characterized in that, Along the width direction of the electrode, the second region is divided into a first coated region and a first uncoated region arranged sequentially, and the fourth region is divided into a second coated region and a second uncoated region arranged sequentially; along the thickness direction, the first coated region and the second coated region are arranged opposite to each other, and the first uncoated region and the second uncoated region are arranged opposite to each other; the thermistor layer is disposed between the first coated region and the second coated region, and the diaphragm is disposed between the first uncoated region and the second uncoated region.

3. The battery as described in claim 2, characterized in that, Along the width direction, the ratio of the width of the thermistor layer to the width of the electrode is 0.15 to 0.20; And / or, along the length direction, the ratio of the length of the thermistor layer to the length of the electrode is 0.2~2%.

4. The battery as described in claim 3, characterized in that, Along the thickness direction, the thickness of the thermistor layer matches the thickness of the active layer.

5. The battery as described in claim 1, characterized in that, The battery also includes tabs, which are disposed at one end of the electrode along the width direction of the electrode sheet; The thermistor layer includes a first thermistor region, a second thermistor region, and a third thermistor region arranged sequentially along the direction from the tab toward the electrode. The first thermistor region has a first temperature threshold, the second thermistor region has a second temperature threshold, and the third thermistor region has a third temperature threshold. The first temperature threshold is less than the second temperature threshold, and the first temperature threshold is less than the third temperature threshold.

6. The battery as described in claim 5, characterized in that, The first temperature threshold < the third temperature threshold < the second temperature threshold.

7. The battery as described in claim 6, characterized in that, The first temperature threshold is 70~80℃, the second temperature threshold is 120~180℃, and the third temperature threshold is 90~105℃.

8. The battery as claimed in claim 1, characterized in that, The thermistor layer comprises NTC material, binder, and ceramic powder.

9. The battery as claimed in claim 8, characterized in that, Based on the mass of the thermistor layer as 100%, the thermistor layer comprises 80-96% NTC material, 2-10% binder and 2-10% ceramic powder.

10. The battery according to any one of claims 1-9, characterized in that, The battery cell includes the electrode and the separator, and the battery cell is a wound core or a stacked core.

11. A battery pack, characterized in that, Includes the battery as described in any one of claims 1-10.

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