Metal lithium battery system and safety early warning and risk elimination method

Abstract

The invention discloses a metal lithium battery system and a safety early warning and risk elimination method, and relates to the field of storage batteries, and the system comprises a sampling module, a control module, a metal lithium battery module and a pressure release load; the metal lithium battery module is connected with a charger or electric equipment through a second lead, and a charging and discharging switch is arranged on the second lead; the pressure release load is connected to the metal lithium battery module through a first lead, and a pressure release switch is arranged on the first lead; the sampling module collects metal lithium battery pack information and sends the metal lithium battery pack information to the control module. The control module is used for controlling on or off of the charge and discharge switch and the pressure release switch, calculating and judging whether a rule is met or not according to the information of the metal lithium battery pack, and sending out a safety early warning signal if the rule is met; the control module controls the charging and discharging switch to be switched off and the pressure release switch to be switched on according to the safety early warning signal so as to eliminate risks in the charging process. The pressure release of the battery module is realized, and the purpose of risk elimination is achieved.

Description

Technical Field

[0001] The present invention relates to the field of storage batteries, and in particular to a metal lithium battery system, which is particularly suitable for safety warning during the charging process of the metal lithium battery and risk elimination after the safety warning occurs. Background Art

[0002] With lithium metal secondary batteries now capable of charge and discharge within a certain cycle and boasting specific energies exceeding 530Wh / kg, they hold great potential for high-energy applications. However, compared to traditional graphite anode materials, lithium metal secondary batteries lack the space for lithium ion insertion, leading to significant volume expansion during charging. This is particularly true for prismatic, flexible-package lithium metal batteries, which can experience thickness expansion of up to 40% at the end of their lifespan.

[0003] However, the metal lithium battery system will experience a very large thickness increase during the charging process, causing the clamping force of the metal lithium battery to exceed the diaphragm's bearing capacity, and then the single battery inside the metal lithium battery system to short-circuit, causing the metal lithium battery system to catch fire and explode, resulting in serious economic losses and even casualties.

[0004] CN 106205029B, "A Power Battery Thermal Runaway Automatic Alarm Device and Method," uses a thermal fuse to detect single cells. When a single cell experiences thermal runaway, the thermal fuse blows, and an automatic thermal runaway alarm is generated by the thermal fuse's blowing. This does not relate to the technical features and alarm method of the present invention. CN 114895187A, "A Battery Management System, Its Voltage and Temperature Detection Method, and Electronic Device," implements system warnings by collecting information such as battery temperature and voltage and performing simple judgments. This does not relate to the technical features of the present invention, such as voltage difference, voltage difference increment, temperature difference, and temperature difference increment, nor does it involve specific methods. Summary of the Invention

[0005] The technical problem solved by this application is: in response to the problem that the safety of metal lithium batteries is difficult to predict in the existing technology, a method for comprehensive evaluation using voltage difference, deformation increment and temperature change rate is proposed. Measures can be taken to avoid safety failures such as internal short circuits, thereby achieving the purpose of accurately predicting and controlling the safety of metal lithium batteries.

[0006] In order to solve the safety risks in the charging process of the metal lithium battery system, the present invention proposes a method for realizing safety warning by judging through information such as the length of the battery module expansion direction, temperature difference, temperature difference increment, voltage difference, and voltage difference increment. The method can comprehensively and effectively detect the internal short circuit risk of the metal lithium battery, and at the same time set a pressure release load to automatically discharge the battery that has a safety warning, thereby releasing the pressure of the battery module in the system and disconnecting the short circuit point, thereby achieving the purpose of eliminating the risk.

[0007] The technical solutions provided in this application are as follows:

[0008] In a first aspect, a metal lithium battery system is provided, comprising a sampling module, a control module, a metal lithium battery module, and a pressure release load;

[0009] The metal lithium battery module is connected to a charger or an electrical device via a second wire, and a charge and discharge switch is provided on the second wire;

[0010] A pressure release load is connected to the metal lithium battery module via a first wire, and a pressure release switch is provided on the first wire to release the power of the metal lithium battery module; the metal lithium battery module includes a plurality of metal lithium battery cells;

[0011] The sampling module collects and sends the lithium metal battery pack information to the control module. The lithium metal battery pack information includes the length L(t) of the lithium metal battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t), and the operating current. The length of the battery module in the expansion direction is the total thickness of all single cells in the battery module tightly stacked in an array.

[0012] The control module is used to control the connection or disconnection of the charge and discharge switch and the pressure release switch. It calculates and analyzes the data of the battery module expansion direction, battery temperature, single cell voltage, and operating current to determine whether the set rules are met. If the rules are met, a safety warning signal is issued; the control module controls the charge and discharge switch to be disconnected and the pressure release switch to be connected according to the safety warning signal to eliminate risks during the charging process.

[0013] Furthermore, it also includes a heating belt, and the control module also includes a heating switch. When the temperature is lower than the set heating start temperature value (for example, 10°C), the heating switch is turned on, and the heating belt heats the metal lithium battery module. When the temperature is higher than the set heating disconnection temperature value (for example, 30°C), the heating switch is disconnected.

[0014] Furthermore, a plurality of the metal lithium battery cells are stacked in an array in a prescribed series-parallel manner to obtain a metal lithium battery module; the voltage range of the metal lithium battery cell is between 2.5V and 4.6V, and the negative electrode material of the metal lithium battery cell is pure lithium or lithium alloy.

[0015] Furthermore, the control module performs calculations and analyses based on the length of the metal lithium battery module in the expansion direction, battery temperature, single cell voltage, and operating current data, including: calculating the battery charge value SOC(t) at time t during the charging process based on the battery temperature T(t), operating current, time, and single cell voltage U(t).

[0016] Furthermore, the rules include:

[0017] L(t)≥∑S 初始放电态 +ΔL 不可逆 (Safety)+ΔL 可逆 ×SOC(t), where ∑S 初始放电态

[0018] is the sum of the thickness of all metal lithium battery cells under discharge conditions; ΔL 不可逆 (Safety) ≥0.2∑S 初始放电态 , ΔL 可逆 =0.18∑S 初始放电态 ;

[0019] Or: ΔU max (t)≥0.2V and U 平均 (t)≥3.9V, or a voltage difference increment ΔU occurs within 2 seconds max (t+2 seconds)-ΔU max (t seconds) ≥ 0.05V and lasts for 3 or more times; where ΔU max (t) is the U(t) of any metal lithium battery cell and the average voltage U of the metal lithium battery cell 平均 The absolute value of the difference between (t);

[0020] Or: Maximum temperature difference increment ΔT of multiple temperature detection points of metal lithium battery module max (t+30 seconds)-ΔT max (t seconds) ≥5℃ for 3 or more times;

[0021] Or: Maximum temperature difference ΔT of multiple temperature detection points of metal lithium battery module max (t seconds) ≥20℃.

[0022] Furthermore, the pressure relief load is installed on the outer surface of the metal lithium battery module, and the pressure relief load is a heating belt, a light bulb or a heat separator.

[0023] Furthermore, the operating current of the pressure release load is not less than 0.05C.

[0024] In a second aspect, a safety warning and risk elimination method for a metal lithium battery system is provided, using any of the metal lithium battery systems described above, comprising:

[0025] S1, start charging program;

[0026] S2. The sampling module detects the metal lithium battery pack information in real time and sends the metal lithium battery pack information to the control module; the metal lithium battery pack information includes the length L(t) of the metal lithium battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t) and the operating current;

[0027] S3. The control module calculates the SOC(t) value based on the battery temperature T(t), operating current, time, and cell voltage U(t);

[0028] S4. The control module determines whether the metal lithium battery module has an internal short circuit or the risk of internal short circuit increases according to the length L(t) of the metal lithium battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t) and the SOC(t) value, and in accordance with the rules;

[0029] S5. If the metal lithium battery module already has an internal short circuit or the risk of internal short circuit increases, the control module disconnects the charging switch and connects the pressure release switch, the pressure load works, the metal lithium battery module consumes power due to the pressure release load, the thickness of the metal lithium battery cell inside the metal lithium battery module decreases, the pressure on the metal lithium battery cell decreases, and the internal short circuit point is disconnected;

[0030] S6. After the pressure load continues to work for a specified time, the pressure release switch is disconnected;

[0031] S7. Record the safety fault information and subsequently operate in a discharge-only mode; repair the safety fault and restore the metal lithium battery system to its initial state.

[0032] Furthermore, in S4, the rules include:

[0033] L(t)≥∑S 初始放电态 +ΔL 不可逆 (Safety)+ΔL 可逆 ×SOC(t), where ∑S 初始放电态

[0034] is the sum of the thickness of all metal lithium battery cells under discharge conditions; ΔL 不可逆 (Safety) ≥0.2∑S 初始放电态 , ΔL 可逆 =0.18∑S 初始放电态 ;

[0035] Or: ΔU max (t)≥0.2V and U 平均 (t)≥3.9V, or a voltage difference increment ΔU occurs within 2 seconds max (t+2 seconds)-ΔU max (t seconds) ≥ 0.05V and lasts for 3 or more times; where ΔU max (t) is the U(t) of any metal lithium battery cell and the average voltage U of the metal lithium battery cell 平均 The absolute value of the difference between (t);

[0036] Or: Maximum temperature difference increment ΔT of multiple temperature detection points of metal lithium battery module max (t+30 seconds)-ΔTmax (t seconds) ≥5℃ for 3 or more times;

[0037] Or: Maximum temperature difference ΔT of multiple temperature detection points of metal lithium battery module max (t seconds) ≥20℃.

[0038] When the above conditions are met, it is determined that the battery module has an internal short circuit or the risk of internal short circuit is increased, and a safety warning signal is issued. Otherwise, it is determined that the battery module does not issue a safety warning signal.

[0039] Furthermore, in S7, the safety fault is repaired, including: finding the fault point and replacing the faulty battery.

[0040] In summary, this application has at least the following beneficial technical effects:

[0041] (1) The present invention adopts a pressure release load design, which discharges the metal lithium battery system during the charging process through the pressure release load, reduces the thickness of the metal lithium battery, reduces the extrusion pressure of the internal short-circuited single battery, disconnects the short-circuit point, and realizes the autonomous release of safety risks.

[0042] (2) The detection information of the sampling module of the present invention includes the length of the battery module in the expansion direction. By checking this length, the density of the metal lithium plating on the surface of the negative electrode inside the metal lithium battery can be quantitatively determined, thereby preventing the negative electrode of the metal lithium battery from forming protrusions sufficient to pierce the diaphragm due to sparse plating, thereby causing safety hazards.

[0043] (3) The present invention uses the length, temperature difference, temperature difference increment, voltage difference, and voltage difference increment of the battery module expansion direction to provide safety warnings, which can comprehensively and effectively detect the internal short circuit risk of metal lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the metal lithium battery system of the present invention.

[0045] Figure 2 This is a safety warning and elimination method for the metal lithium battery system of the present invention. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of this application clearer, the embodiments disclosed in this application will be described in further detail below with reference to the accompanying drawings.

[0047] The present application discloses a metal lithium battery system, a safety warning and risk elimination method, such as Figure 1 As shown, Figure 1 The invention provides a lithium metal battery system, comprising a sampling module, a control module, a lithium metal battery module, a pressure release load, and a heating belt.

[0048] The sampling module collects information about the lithium metal battery pack, including the length of the battery module in the expansion direction, battery temperature, cell voltage, and operating current. The sampling module feeds this information back to the control system. The expansion length of the battery module is the total thickness of all the cells in the module, tightly stacked in an array. This length increases with charging and decreases with discharging. When the battery module expands to a certain initial thickness, typically a maximum of 40%, the probability of an internal short circuit in the battery module increases significantly.

[0049] The battery module is connected to the control module through a power circuit, and the circuit is distributed through the control module.

[0050] The control module is used to control the on / off of the charge / discharge switch, the pressure release switch, and the heating switch. The charge / discharge switch controls charge and discharge, the pressure release switch discharges the lithium metal battery system during charging, reducing the thickness of the lithium metal battery, lowering the extrusion pressure of the lithium metal battery, and automatically disconnecting the internal short circuit point of the lithium metal battery. The heating switch heats the battery pack at low temperatures.

[0051] The heating belt is a heating element for heating the battery pack module. The purpose of heating is achieved by energizing the heating belt.

[0052] The metal lithium battery module includes multiple metal lithium battery cells, which are stacked in an array according to a prescribed series-parallel connection method; the voltage range of the metal lithium battery cells is between 2.5V and 4.6V, and the negative electrode material is pure lithium or lithium alloy.

[0053] The pressure release load is installed on the outer surface of the battery pack, and is generally a heating belt, a light bulb, a heat separator, etc. The working current of the pressure release load is not less than 0.05C; when a safety warning occurs in the metal lithium battery system during charging, the control module disconnects the charge and discharge switch to stop charging, and then turns on the pressure release load switch to release the power of the battery module, so that the pressure release of the battery module can be effective; the control module analyzes and calculates the length of the metal lithium battery module in the expansion direction, the battery temperature, the single cell voltage, and the working current data, and issues a safety warning during the charging process according to the prescribed method.

[0054] Parameter Description:

[0055] The initial length L(0) of the battery module in the expansion direction. ∑S 初始放电态 It is the sum of the thicknesses of all fresh metal lithium battery cells under discharge conditions. Fresh refers to newly produced metal lithium battery cells.

[0056] L(0)=∑S 初始放电态 .

[0057] ΔL 不可逆 (Safety) is the maximum irreversible thickness increase allowed for the battery module without internal short circuit.

[0058] ΔL 可逆 It is the maximum thickness difference between the charged state thickness and the discharged state thickness of the battery module in the same cycle.

[0059] SOC(t) is the battery capacity parameter, that is, the battery capacity value at time t during the charging process, which can be calculated through current integration, operating voltage, temperature, etc.

[0060] Figure 2 The safety warning and elimination method of the metal lithium battery system of the present invention is as follows:

[0061] Step 1: Start the charging process;

[0062] Step 2: The sampling module detects and collects the metal lithium battery pack information in real time and sends the metal lithium battery pack information to the control module. The metal lithium battery pack information includes single cell voltage, battery temperature, operating current, and length data of the metal lithium battery module in the expansion direction;

[0063] Step 3: The control module calculates the SOC(t) value based on the battery temperature T(t), operating current, time, and cell voltage U(t);

[0064] Step 4: The control module determines that the battery module has an internal short circuit or the risk of internal short circuit has increased according to the rules. The specific rules are as follows:

[0065] L(t)≥∑S 初始放电态 +ΔL 不可逆 (Safety)+ΔL 可逆 × SOC(t), where ΔL is generally 不可逆 (Safety) ≥0.2∑S 初始放电态 , ΔL 可逆 =0.18∑S 初始放电态 ; Wherein, L(t) is the real-time measured length of the metal lithium battery module in the direction of battery module expansion;

[0066] Or any single cell voltage U(t) and the average single cell voltage U 平均 The absolute value of the difference between (t) is ΔU max (t), satisfying ΔU max (t)≥0.2V and U 平均 (t)≥3.9V, or a voltage difference increment ΔU occurs within 2 seconds max (t+2 seconds)-ΔU max (t seconds) ≥ 0.05V and lasts for 3 or more times; where U(t) is the cell voltage;

[0067] Or the maximum temperature difference increment ΔT of multiple temperature detection points on the battery module body max (t+30 seconds)-ΔT max (t seconds) ≥5℃ for 3 or more times;

[0068] Or the maximum temperature difference ΔT of multiple temperature detection points on the battery module body max (t seconds) ≥20℃.

[0069] Step 5: The control module turns off the charging switch and turns on the pressure release switch. The pressure load works, and the battery module consumes electricity due to the pressure release load. The thickness of the single battery inside the battery module decreases, the pressure on the single battery decreases, and the internal short circuit point is disconnected;

[0070] Step 6: The pressure load continues to operate until the internal short circuit or the risk of internal short circuit described in step 4 is eliminated, and the pressure release switch is disconnected;

[0071] Step 7: Record the safety fault information and subsequently operate in a discharge-only mode; repair the safety fault and restore the lithium metal battery system to its initial state. Repairing the safety fault includes locating the fault point and replacing the faulty battery.

[0072] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

[0073] The present application has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present application, all of which fall within the scope of the present application. The scope of protection of the present application shall be determined by the appended claims.

Claims

1. A metal lithium battery system, characterized in that: Includes sampling module, control module, metal lithium battery module and pressure release load; The metal lithium battery module is connected to a charger or an electrical device via a second wire, and a charge and discharge switch is provided on the second wire; A pressure release load is connected to the metal lithium battery module via a first wire, and a pressure release switch is provided on the first wire to release the power of the metal lithium battery module; the metal lithium battery module includes a plurality of metal lithium battery cells; The sampling module collects the lithium metal battery pack information and sends it to the control module. The lithium metal battery pack information includes the length L(t) of the lithium metal battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t) and the operating current; The length of the battery module in the expansion direction is the total thickness of all the single cells in the battery module tightly stacked in an array; The control module is used to control the connection or disconnection of the charge and discharge switch and the pressure release switch. It calculates and analyzes the battery module expansion length, battery temperature, single cell voltage, and operating current data to determine whether the set rules are met. If the rules are met, a safety warning signal is issued; The control module controls the charge and discharge switch to be disconnected and the pressure release switch to be connected according to the safety warning signal to eliminate risks during the charging process.

2. A metal lithium battery system according to claim 1, characterized in that: It also includes a heating belt, and the control module also includes a heating switch. When the temperature is lower than the set heating start temperature value, the heating switch is turned on and the heating belt heats the metal lithium battery module. When the temperature is higher than the set heating disconnection value, the heating switch is disconnected.

3. The metal lithium battery system according to claim 1, characterized in that: A plurality of the metal lithium battery cells are stacked in an array in a prescribed series-parallel manner to obtain a metal lithium battery module; the voltage range of the metal lithium battery cell is between 2.5V and 4.6V, and the negative electrode material of the metal lithium battery cell is pure lithium or lithium alloy.

4. A metal lithium battery system according to claim 1, characterized in that: The control module performs calculations and analyses based on the length of the metal lithium battery module in the expansion direction, battery temperature, single cell voltage, and operating current data, including: calculating the battery charge value SOC(t) at time t during the charging process based on the battery temperature T(t), operating current, time, and single cell voltage U(t).

5. The metal lithium battery system according to claim 1, characterized in that: The rules include: L(t)≥∑S 初始放电态 +ΔL 不可逆 (Safety)+ΔL 可逆 ×SOC(t), where ∑S 初始放电态 is the sum of the thickness of all metal lithium battery cells under discharge conditions; ΔL 不可逆 (Safety) ≥0.2∑S 初始放电态 , ΔL 可逆 =0.18∑S 初始放电态 ; Or: ΔU max (t)≥0.2V and U 平均 (t)≥3.9V, or a voltage difference increment ΔU occurs within 2 seconds max (t+2 seconds)-ΔU max (t seconds) ≥ 0.05V and lasts for 3 or more times; where ΔU max (t) is the U(t) of any metal lithium battery cell and the average voltage U of the metal lithium battery cell 平均 The absolute value of the difference between (t); Or: Maximum temperature difference increment ΔT of multiple temperature detection points of metal lithium battery module max (t+30 seconds)-ΔT max (t seconds) ≥5℃ for 3 or more times; Or: Maximum temperature difference ΔT of multiple temperature detection points of metal lithium battery module max (t seconds) ≥20℃.

6. The metal lithium battery system according to claim 1, characterized in that: The pressure relief load is installed on the outer surface of the metal lithium battery module, and the pressure relief load is a heating belt, a light bulb or a heat separator.

7. The metal lithium battery system according to claim 1, characterized in that: The operating current of the pressure release load is not less than 0.05C.

8. A safety warning and risk elimination method for a metal lithium battery system, characterized in that: A metal lithium battery system according to any one of claims 1 to 7, comprising: S1, start charging program; S2. The sampling module detects the metal lithium battery pack information in real time and sends the metal lithium battery pack information to the control module; the metal lithium battery pack information includes the length L(t) of the metal lithium battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t) and the operating current; S3. The control module calculates the SOC(t) value based on the battery temperature T(t), operating current, time, and cell voltage U(t); S4. The control module determines whether the metal lithium battery module has an internal short circuit or the risk of internal short circuit increases according to the length L(t) of the metal lithium battery module in the expansion direction, the battery temperature T(t), the single cell voltage U(t) and the SOC(t) value, and in accordance with the rules; S5. If the metal lithium battery module already has an internal short circuit or the risk of internal short circuit increases, the control module disconnects the charging switch and connects the pressure release switch, the pressure load works, the metal lithium battery module consumes power due to the pressure release load, the thickness of the metal lithium battery cell inside the metal lithium battery module decreases, the pressure on the metal lithium battery cell decreases, and the internal short circuit point is disconnected; S6. After the pressure load continues to work for a specified time, the pressure release switch is disconnected; S7. Record the safety fault information and subsequently operate in a discharge-only mode; repair the safety fault and restore the metal lithium battery system to its initial state.

9. The safety warning and risk elimination method for a metal lithium battery system according to claim 8, characterized in that: In S4, the rules include: L(t)≥∑S 初始放电态 +ΔL 不可逆 (Safety)+ΔL 可逆 ×SOC(t), where ∑S 初始放电态 is the sum of the thickness of all metal lithium battery cells under discharge conditions; ΔL 不可逆 (Safety) ≥0.2∑S 初始放电态 , ΔL 可逆 =0.18∑S 初始放电态 ; Or: ΔU max (t)≥0.2V and U 平均 (t)≥3.9V, or a voltage difference increment ΔU occurs within 2 seconds max (t+2 seconds)-ΔU max (t seconds) ≥ 0.05V and lasts for 3 or more times; where ΔU max (t) is the U(t) of any metal lithium battery cell and the average voltage U of the metal lithium battery cell 平均 The absolute value of the difference between (t); Or: Maximum temperature difference increment ΔT of multiple temperature detection points of metal lithium battery module max (t+30 seconds)-ΔT max (t seconds) ≥5℃ for 3 or more times; Or: Maximum temperature difference ΔT of multiple temperature detection points of metal lithium battery module max (t seconds) ≥20℃. When the above conditions are met, it is determined that the battery module has an internal short circuit or the risk of internal short circuit is increased, and a safety warning signal is issued. Otherwise, it is determined that the battery module does not issue a safety warning signal.

10. The safety warning and risk elimination method for a metal lithium battery system according to claim 8, characterized in that: In S7, the safety fault is repaired, including: finding the fault point and replacing the faulty battery.

Images