Lithium battery thermal runaway suppression device and method

Abstract

The invention discloses a device and a method for inhibiting thermal runaway of a lithium battery. The device comprises a battery shell, an NTC (Negative Temperature Coefficient) resistor connected with a positive tab or a negative tab of the battery and memory alloy connected with the negative tab or the positive tab of the battery are arranged in the battery shell, and the NTC resistor and the memory alloy cannot be connected with the positive tab or the negative tab of the battery at the same time; and the memory alloy can be subjected to phase change along with the temperature change, so that the connection with the NTC resistor is automatically disconnected or connected. When the temperature of the battery rises and the temperature of the memory alloy reaches the phase change temperature, the memory alloy is unfolded and straightened from a folded shape to be connected with the NTC resistor, the positive electrode and the negative electrode are conducted, the battery is slowly discharged, the SOC is reduced, thermal runaway of the battery is prevented, and the memory alloy is reset after the temperature is reduced. On the premise of not influencing the electrical performance of the battery, the thermal runaway of the battery can be effectively inhibited, the thermal safety performance of the battery is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lithium electronics technology, and in particular to a lithium battery thermal runaway suppression device and method. Background Technology

[0002] In pursuit of longer driving range, lithium-ion batteries are becoming increasingly energy-dense, typically using nickel-cobalt-manganese materials. However, ternary materials have poor thermal stability. To improve the safety performance of ternary material batteries, technologies such as positive electrode coating, positive and negative electrode functional coatings, thicker diaphragms, and high-temperature resistant electrolytes are commonly used. These technical measures not only affect the battery's energy density, charge and discharge capacity, and cycle performance, but also have limited improvement on the thermal safety of lithium batteries. In particular, when the positive electrode uses nickel-cobalt-manganese 811 or higher materials, the above measures cannot fundamentally improve the battery's thermal safety performance. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a lithium battery thermal runaway suppression device and method, which can effectively suppress battery thermal runaway, improve battery thermal safety performance, and extend battery life without affecting battery electrical performance.

[0004] According to the present invention, a battery thermal runaway suppression device includes a battery casing; the battery casing is provided with an NTC resistor connected to a positive or negative tab, and a shape memory alloy connected to a negative or positive tab, wherein the NTC resistor and the shape memory alloy cannot be connected to the positive or negative tab of the battery at the same time; the shape memory alloy can undergo a phase change with temperature change, thereby automatically disconnecting or connecting to the NTC resistor.

[0005] In some embodiments of the present invention, the NTC resistor and the shape memory alloy are protected by high-temperature tape on the outer side near the battery casing to prevent the NTC resistor and the shape memory alloy from contacting the battery casing and short-circuiting.

[0006] In some embodiments of the present invention, the NTC resistor is a cuboid or cylinder, with an aluminum strip leading out from its interior. The NTC resistor is welded to the positive or negative tab of the battery via the aluminum strip by ultrasonic welding or laser welding.

[0007] In some embodiments of the present invention, the shape memory alloy is welded to the positive or negative electrode tab of the battery by ultrasonic welding or laser welding, and it is W-shaped folded at room temperature, disconnected from the NTC resistor.

[0008] In some embodiments of the present invention, the following steps are included:

[0009] When the battery temperature rises, the NTC resistor connected to the positive electrode of the battery decreases with the increase in temperature. When the battery temperature reaches the phase transition temperature, the shape memory alloy connected to the negative electrode of the battery opens from its folded state and straightens, connecting to the NTC resistor, conducting the positive and negative electrodes, slowly discharging the battery, reducing the SOC, preventing thermal runaway, and improving thermal safety.

[0010] When the battery temperature drops below the phase transition temperature of the memory alloy, the memory alloy returns to its W-shaped folded state, and the memory alloy is disconnected from the NTC resistor.

[0011] In some embodiments of the present invention, the shape memory alloy is composed of one or more of nickel-titanium-based alloys, copper-based alloys, iron-based alloys, titanium-based alloys, noble metal-based alloys, and porous nickel-titanium-nobel alloys.

[0012] In some embodiments of the present invention, the phase transformation temperature of the shape memory alloy is T, where 100℃≤T≤130℃.

[0013] In some embodiments of the present invention, the reference resistance value of the NTC resistor at 25°C is ≥5KΩ, and its resistance rapidly decreases to 200Ω-500Ω after the temperature exceeds 100°C.

[0014] Compared with existing technologies, this invention utilizes the temperature-sensitive properties of shape memory alloys. The deformation of the shape memory alloy drives the switching of its connection state with the NTC resistor, achieving temperature-controlled on / off switching of the circuit. When the battery temperature rises and the shape memory alloy reaches its phase transition temperature, the alloy unfolds from its folded state and straightens to connect with the NTC resistor, conducting between the positive and negative terminals and slowly discharging the battery, reducing its state of charge (SOC). This effectively prevents battery thermal runaway and improves electromagnetic thermal safety. This invention is simple and easy to implement, effectively suppressing battery thermal runaway and has broad application prospects. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of a lithium battery thermal runaway suppression device before heating, according to an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the heated structure of a lithium battery thermal runaway suppression device according to an embodiment of the present invention;

[0017] Figure 3 This is a schematic diagram of the voltage decrease over time of a lithium battery cell after heating, according to an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the voltage decrease over time of a lithium battery cell after heating, according to an embodiment of the present invention.

[0019] Figure 5This is the folded state of the shape memory alloy of the lithium battery thermal runaway suppression device at room temperature according to an embodiment of the present invention;

[0020] Figure 6 This is the state of the lithium battery thermal runaway suppression device after reaching the phase transition temperature and being stretched, according to an embodiment of the present invention.

[0021] In the diagram: 1. NTC resistor; 2. Shape memory alloy; 3. Battery casing. Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] The following is for reference. Figures 1 to 6 As shown, a lithium battery thermal runaway suppression device according to an embodiment of the present invention is described, including a battery casing 3, a battery placed inside the battery casing 3, an NTC resistor 1 connected to the positive or negative tab of the battery, and a shape memory alloy 2 connected to the negative or positive tab of the battery, wherein the NTC resistor 1 and the shape memory alloy 2 cannot be connected to the positive or negative tab of the battery at the same time; the shape memory alloy 2 can undergo a phase change with temperature change, thereby automatically disconnecting or connecting to the NTC resistor 1.

[0024] Specifically, shape memory alloy 2 has a temperature-controlled shape memory function. By using shape memory alloy 2 as a temperature control switch, its shape changes with temperature, thereby controlling the connection and disconnection of NTC resistor 1 in the circuit.

[0025] In some embodiments, the NTC resistor 1 and the shape memory alloy 2 of the present invention are protected by high-temperature tape on the outer side near the battery casing 3 to prevent short circuits caused by contact between the NTC and the shape memory alloy 2 and the battery casing 3. In this embodiment, the high-temperature tape is a polyimide high-temperature tape.

[0026] In some embodiments, the NTC resistor 1 of the present invention is a cuboid or cylinder, with an aluminum strip leading out from its interior. The NTC resistor 1 is welded to the positive or negative tab of the battery by ultrasonic welding or laser welding through the aluminum strip.

[0027] In some embodiments, the shape memory alloy 2 of the present invention is welded to the positive or negative electrode tab of the battery by ultrasonic welding or laser welding. At room temperature, it exhibits a continuous W-shaped fold and is not connected to the NTC resistor 1. (Refer to...) Figure 1 and Figure 5 As shown.

[0028] Based on the above-described apparatus, the lithium battery thermal runaway suppression method of the present invention includes the following steps:

[0029] As the battery temperature rises, the NTC resistor 1 connected to the positive terminal decreases, and the temperature of the shape memory alloy 2 also rises. When the temperature of the shape memory alloy 2 reaches the phase transition temperature, which is T, 100℃≤T≤130℃, the shape memory alloy 2 connected to the negative terminal opens from its folded state and straightens, connecting to the NTC resistor 1. (Refer to...) Figure 2 and Figure 6 As shown, the positive and negative terminals are connected to slowly discharge the battery, reduce the state of charge (SOC), prevent thermal runaway, and improve thermal safety.

[0030] When the ambient temperature and battery temperature drop below the phase transition temperature T of the memory alloy, the memory alloy 2 returns to the W-shaped folded state and can be reused. At this time, the memory alloy 2 is disconnected from the NTC resistor 1.

[0031] Using the device of this embodiment, when the battery is in a high-temperature environment, the temperature may remain high during the slow discharge process due to the influence of the ambient temperature, which may cause the battery to be scrapped, but thermal runaway will not occur, effectively avoiding the danger of the battery smoking, catching fire or even exploding.

[0032] Specifically, in this embodiment, the NTC resistor 1 has a reference resistance value of ≥5KΩ at 25℃, and its resistance rapidly decreases to 200Ω-500Ω after the temperature exceeds 100℃. The discharge rate of the battery is controlled by adjusting the temperature sensitivity coefficient of the NTC resistor, and the discharge rate can be controlled between 150-250mV / h, ensuring that the battery discharges within a safe temperature range. In this embodiment, the shape memory alloy 2 is composed of one or more of the following: nickel-titanium based alloy, copper-based alloy (Cu-Al-Ni, Cu-Zn-Al, Cu-Al-Mn, Cu-Sn), iron-based alloy (Fe-Mn-Si, Fe-Ni-Co-Ti, Fe-Pt, Fe-Pd, Fe-Ni-Al), titanium-based alloy (Ti-Nb, Ti-Nb-X (X=Ta, Zr, Sn, Mo, etc.)), noble metal-based alloy (Au-Cd, Ag-Cd, Pt), and porous nickel-titanium alloy. In practical applications, the composition of the shape memory alloy can be selected according to actual needs.

[0033] Example 1

[0034] In this embodiment, the positive electrode material is a nickel-cobalt-manganese 811 ternary material, the negative electrode material is graphite, the electrode assembly is in a stacked form, and the cell structure is an aluminum square shell; NTC resistor 1 is composed of 95% manganese oxide, nickel oxide, and cobalt oxide (60:30:10), and 5% vanadium pentoxide, with a reference resistance value of approximately 6KΩ at 25°C; shape memory alloy 2 is nickel-titanium based; reference Figure 3As shown, Figure 3 The graph shows the voltage of the battery cell decreasing over time after heating. It is clear from the graph that the voltage decreases over time after the cell is heated, indicating that the SOC is slowly decreasing to prevent thermal runaway of the battery.

[0035] Example 2

[0036] In this embodiment, the positive electrode material is a nickel-cobalt-manganese 811 ternary material, the negative electrode material is graphite, the electrode assembly is in a stacked form, and the cell structure is a soft-pack; NTC resistor 1 is composed of 95% manganese oxide, nickel oxide, and cobalt oxide (60:30:10), and 5% vanadium pentoxide, with a reference resistance value of approximately 8KΩ at 25°C; shape memory alloy 2 is nickel-titanium based; reference Figure 4 As shown, Figure 4 The graph shows the voltage of the battery cell decreasing over time after heating. It is clear from the graph that the voltage decreases over time after the cell is heated, indicating that the SOC is slowly decreasing to prevent thermal runaway of the battery.

[0037] The above embodiments illustrate that, after the battery temperature rises, the present invention effectively reduces the SOC (state of charge) through a slow discharge scheme, thereby preventing thermal runaway and improving thermal safety.

[0038] In batteries with high SOC (State of Charge), the positive electrode material is in a deeply delithiated state, resulting in structural instability. Lithium ions are embedded between graphite layers, leading to high chemical activity. When the temperature rises, the positive electrode material easily decomposes, releasing oxygen and a large amount of heat, further triggering a chain reaction in the negative electrode, releasing even more heat and potentially causing thermal runaway, especially with high-nickel ternary materials, which exhibit even worse high-temperature stability. This invention utilizes an NTC resistor to slowly discharge the battery, gradually releasing the internal chemical energy and transforming it from a "high-energy state" prone to violent reactions to a stable "low-energy state," thereby fundamentally suppressing battery thermal runaway. Specifically, in this embodiment, after slow discharge using an NTC resistor, the battery's SOC decreases. At this point, more lithium ions are "locked" within the positive electrode material's lattice, making the positive electrode material more stable. The temperature threshold required for its decomposition is significantly increased, and its chemical activity is significantly reduced, effectively suppressing battery thermal runaway.

[0039] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A lithium battery thermal runaway suppression device, characterized by, The application relates to a battery temperature self-regulating device. The battery shell is internally provided with an NTC resistance connected with a positive or negative battery tab and a memory alloy connected with a negative or positive battery tab, and the NTC resistance and the memory alloy cannot be simultaneously connected with the positive or negative battery tab. The memory alloy can change phase with temperature change, thereby automatically disconnecting or connecting with the NTC resistance. The NTC resistance and the memory alloy are protected by high-temperature adhesive tape close to the outside of the battery shell.

2. The lithium battery thermal runaway suppression device of claim 1, wherein, The NTC resistance is a cuboid or a cylinder, and the inside of the NTC resistance is led out by an aluminum tape, and the NTC resistance is welded on the positive or negative battery tab by ultrasonic welding or laser welding.

3. The device of claim 1, wherein the device is configured to: The memory alloy is welded on the positive or negative battery tab by ultrasonic welding or laser welding, and the memory alloy is in a W-fold state at normal temperature and is disconnected with the NTC resistance.

4. The lithium battery thermal runaway mitigation device of claim 1, wherein, The application comprises the following steps:

5. A suppression method using the lithium battery thermal runaway suppression device according to any one of claims 1 to 4, characterized by, When the battery temperature rises, the NTC resistance connected with the positive battery tab decreases with the temperature rise, and when the battery temperature reaches the phase change temperature, the memory alloy connected with the negative battery tab is opened and stretched from the folded state, connected with the NTC resistance, and the positive and negative electrodes are conducted to slowly discharge the battery and reduce the SOC. When the battery temperature decreases to below the phase change temperature of the memory alloy, the memory alloy returns to the W-fold state, and the memory alloy is disconnected with the NTC resistance. The memory alloy is composed of one or more of a nickel-titanium-based alloy, a copper-based alloy, an iron-based alloy, a titanium-based alloy, a noble metal-based alloy and a porous nickel-titanium alloy.

6. The method of claim 5, wherein the lithium battery is a lithium ion battery. The NTC resistance is composed of 95% manganese oxide, nickel oxide and cobalt oxide and 5% vanadium pentoxide.

7. The method of claim 5, wherein the lithium battery is a lithium ion battery. The ratio of the manganese oxide, the nickel oxide and the cobalt oxide is 60:30:

10.

8. The method of claim 7, wherein the lithium battery is a lithium ion battery. The phase change temperature of the memory alloy is T, and 100 DEG C <= T <= 130 DEG C.

9. The method of claim 5, wherein the lithium battery is a lithium ion battery. The reference resistance value of the NTC resistance at 25 DEG C is >= 5K omega, and the resistance rapidly decreases to 200 omega-500 omega after the temperature exceeds 100 DEG C.

10. The method of claim 5, wherein the lithium battery is a lithium ion battery. ​

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