A method of baking a battery
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EVE POWER CO LTD
- Filing Date
- 2024-02-29
- Publication Date
- 2026-06-30
AI Technical Summary
The current lithium-ion battery baking process has a slow heating rate, resulting in excessively long baking time, increased energy consumption, and reduced production efficiency.
The battery is preheated by heating at a temperature higher than the baking temperature, and the heating temperature is reduced as the battery temperature rises. Combined with inert gas filling and vacuuming operations, the battery heating rate and safety are controlled.
It shortens baking time, reduces oven energy consumption, improves production efficiency, and ensures battery safety.
Smart Images
Figure CN118054093B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, and more particularly to a method for baking a battery. Background Technology
[0002] Lithium-ion batteries, as a new type of clean and renewable secondary energy source, have advantages such as high energy density, low self-discharge, good safety performance and rate performance. They have become an excellent energy source for electronic devices and electric vehicles and are widely used. Lithium battery companies not only focus on improving product quality, but also on improving production efficiency and reducing production costs.
[0003] During the production of lithium-ion batteries, the water content of the electrodes must be strictly controlled to ensure the electrochemical and safety performance of the battery. Excessive water content in the electrodes can lead to battery swelling, reduced capacity, or even serious safety problems.
[0004] In existing technologies, batteries are typically baked before electrolyte injection, which involves heating and maintaining the battery temperature in a baking oven to dry the moisture on the electrodes. However, current lithium-ion batteries heat up slowly during baking, resulting in excessively long baking times, which increases the energy consumption of the baking oven and reduces production efficiency. Summary of the Invention
[0005] The purpose of this invention is to provide a battery baking method that can reduce baking time, reduce the energy consumption of the baking oven, and improve production efficiency.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] A method for baking a battery, comprising:
[0008] Heating: The battery is heated to a baking temperature T0, the heating temperature T1 is higher than T0, and the heating temperature T1 decreases as the battery temperature T2 increases.
[0009] Baking: The battery is baked at the baking temperature T0 and kept warm for a period of time.
[0010] As an alternative to the baking method for the above-mentioned battery, during the heating process of the battery, the heating temperature T1 = k(T0-T2) + T0 is controlled.
[0011] As an alternative to the baking method for the battery described above, in the heating step, the heating temperature T1 is changed every first time interval.
[0012] As an optional method for baking the battery, k≤0.2, and the maximum value of the heating temperature T1 is the baking temperature T0+15℃.
[0013] As an optional method for baking the above-mentioned battery, the baking temperature T0 is in the range of 90℃~100℃.
[0014] As an optional embodiment of the above-mentioned battery baking method, before the heating step, the method further includes:
[0015] Gas filling: The baking chamber is evacuated and then filled with a gas that is inert to the battery.
[0016] As an alternative to the baking method for the above-mentioned battery, the gas that is inert to the battery is one of nitrogen, helium and argon.
[0017] As an optional embodiment of the above-mentioned battery baking method, after the heating step, the method further includes:
[0018] Vacuuming is performed on the baking cavity before proceeding with the baking steps.
[0019] The baking step also includes:
[0020] The baking chamber is filled with a gas that is inert to the battery. After maintaining this for a second time interval, the baking chamber is evacuated.
[0021] Repeat the above operation after the third time interval.
[0022] As an optional embodiment of the baking method for the aforementioned battery, the baking method further includes:
[0023] The temperature of the battery is monitored to ensure that the temperature of the battery is lower than the baking temperature T0.
[0024] As an optional embodiment of the above-mentioned battery baking method, monitoring the temperature of the battery includes:
[0025] The internal temperature of the top, middle and bottom of the battery is monitored.
[0026] The beneficial effects of this invention are:
[0027] This invention provides a method for baking a battery. Before baking the battery, the battery is heated at a temperature T1 higher than the baking temperature T0, so that the battery's heating rate is greater than the heating rate when the battery is heated at the baking temperature T0, thereby shortening the overall baking time.
[0028] This baking method can reduce baking time, reduce oven energy consumption, and improve production efficiency. Attached Figure Description
[0029] Figure 1This is a flowchart of the battery baking method provided by the present invention. Detailed Implementation
[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments 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.
[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.
[0032] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.
[0033] Unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" of a second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0035] During the production of lithium-ion batteries, the water content of the electrodes must be strictly controlled to ensure the electrochemical and safety performance of the battery. Excessive water content in the electrodes can lead to battery swelling, reduced capacity, or even serious safety problems.
[0036] In existing technologies, batteries are typically baked before electrolyte injection, which involves heating and maintaining the battery temperature in a baking oven to dry the moisture on the electrodes. However, current lithium-ion batteries heat up slowly during baking, resulting in excessively long baking times, which increases the energy consumption of the baking oven and reduces production efficiency.
[0037] To address the aforementioned problems, this embodiment provides a battery baking method, such as... Figure 1 As shown, the baking method includes:
[0038] Heating: The battery is heated to a baking temperature T0. The heating temperature T1 is higher than T0, and the heating temperature T1 decreases as the battery temperature T2 increases.
[0039] Baking: The battery is baked at baking temperature T0 and kept warm for a period of time.
[0040] Before baking, the battery is heated to a temperature T1 higher than the baking temperature T0. Since the battery's heating rate is related to the difference between the heating temperature T1 and the battery temperature T2 (a larger difference results in a higher heating rate), this heating method allows for a higher heating rate than traditional baking methods that directly use the baking temperature T0, thus shortening the overall baking time. This baking method reduces baking time, lowers oven energy consumption, and improves production efficiency.
[0041] Moreover, the heating temperature T1 in this baking method decreases as the battery temperature T2 increases, which causes the battery heating rate to decrease as the battery temperature T2 increases. In other words, the closer the battery temperature T2 is to the baking temperature T0, the slower the battery heats up. This ensures the battery heating rate while preventing the battery temperature T2 from exceeding the baking temperature T0 and causing battery damage.
[0042] During the heating process, the rate of change of baking temperature T0 and the rate of change of heating temperature T1 both decrease with the extension of time, so that the battery temperature T2 slowly and steadily rises when it is close to the baking temperature T0. When the battery temperature T2 rises to equal the baking temperature T0, the heating temperature T1 drops to the baking temperature T0. At this time, the temperature inside the baking oven is in a stable state, and the battery is baked at a constant temperature.
[0043] In this embodiment, the baking temperature T0 ranges from 90°C to 100°C. Current lithium-ion batteries are made of various materials; if the temperature is too high, there is a risk of fire and runaway; if the temperature is too low, the rate of moisture removal is too slow. Specifically, the baking temperature T0 can be 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, or 100°C.
[0044] In this embodiment, the battery is placed on a tray and then enters the baking chamber of the oven. The heating module of the oven is located at the bottom of the tray, and the battery is heated through the tray. To prevent the battery from oxidizing during the heating process, the baking chamber needs to be evacuated before heating, so that the battery can only absorb heat through the tray. This results in uneven heating of the battery from top to bottom and a slower heating rate.
[0045] To solve the above problems, the following steps are included before the heating step:
[0046] Gas filling: The baking chamber is evacuated and then filled with a gas that is inert to the battery.
[0047] Among them, the inert gas for the battery refers to the gas that does not react with the various structures of the battery at the baking temperature T0 and the heating temperature T1, so as to avoid the battery being oxidized or corroded. At the same time, the gas can also be used as an auxiliary medium to heat the battery, shorten the battery heating time and improve efficiency.
[0048] Specifically, the gas that is inert to the battery is one of nitrogen, helium, or argon. These gases are all stable gases that are difficult to react with other substances. They will not react with the various structures of the battery at the baking temperature T0 and the heating temperature T1, making them good protective gases. They can also conduct heat to heat the battery.
[0049] In this embodiment, after evacuating the baking chamber, nitrogen gas is introduced into the baking chamber at a pressure of 70 kPa to 100 kPa. Higher nitrogen pressure results in better thermal conductivity, thereby increasing the heating speed of the battery. However, the nitrogen pressure should not be too high, otherwise it will increase costs and may damage the battery or the baking chamber. Specifically, the nitrogen pressure can be 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, or 100 kPa.
[0050] Since the heating temperature T1 is related to both the battery temperature T2 and the predetermined baking temperature T0, the temperature inside the baking oven needs to be set according to the battery temperature T2 and the baking temperature T0 to achieve controllability of the battery heating process.
[0051] Since the heating temperature T1 decreases as the battery temperature T2 increases, and eventually both are equal to the baking temperature T0, the differences T1-T0 and T0-T2 increase or decrease synchronously. Therefore, the ratio of the two is (T1-T0) / (T0-T2) = k, where k is a coefficient.
[0052] The above formula can be transformed to control the heating temperature T1 = k(T0-T2) + T0 during the battery heating process. Since the baking temperature T0 is a fixed value before heating begins, and the battery temperature T2 is generally room temperature and usually a fixed value, the value of k is related to the maximum value of the heating temperature T1, thus affecting the battery's heating rate, and ultimately affecting the heating time and the total baking time.
[0053] Understandably, a larger value for k results in a larger heating temperature T1. While this increases the battery's heating rate, excessively high temperatures can also damage the battery or even cause localized overheating and fire. To address this issue, k ≤ 0.2, limiting the initial heating temperature T1 to prevent potential hazards.
[0054] In this embodiment, the baking temperature T0 = 95°C and the initial battery temperature T2 = 20°C are used as examples for explanation.
[0055] When k = 0.2, the initial heating temperature T1 = 110℃. As the heating time increases, the battery temperature T2 gradually increases, and the heating temperature T1 decreases accordingly. (Based on experimental records:)
[0056] After heating for 1 hour, the battery temperature T2 rises to 45°C, while the heating temperature T1 at this time is 105°C.
[0057] After heating for 2 hours, the battery temperature T2 rises to 60°C, while the heating temperature T1 at this time is 102°C.
[0058] After heating for 3 hours, the battery temperature T2 rises to 75°C, while the heating temperature T1 at this time is 99°C.
[0059] After heating for 4 hours, the battery temperature T2 rises to 85°C, while the heating temperature T1 at this time is 97°C.
[0060] After heating for 5 hours, the battery temperature T2 rises to 95℃, at which point the heating temperature T1 is 95℃.
[0061] In other words, after heating for 5 hours, the battery temperature T2 is equal to the baking temperature T0. At this point, the battery can be baked at a constant temperature.
[0062] When k = 0.15, the initial heating temperature T1 = 106.25℃;
[0063] When k = 0.1, the initial heating temperature T1 = 102.5℃.
[0064] The value of coefficient k can be determined based on the battery's specifications, size, type, and the expected heating time.
[0065] Similarly, if the battery temperature T2 is low, for example, when T2 = 0℃ and k = 0.2, the corresponding heating temperature T1 = 114℃, which would result in a relatively high heating temperature T1, also posing a risk of excessively high heating temperature T1. In this embodiment, the maximum value of the heating temperature T1 is the baking temperature T0 + 15℃, in order to achieve a double limit on the heating temperature T1 at the start of heating and avoid danger.
[0066] In order to accurately control the change in battery temperature T2 and thus change the heating temperature T1, the battery temperature needs to be monitored during the baking process to ensure that the battery temperature is lower than the baking temperature T0.
[0067] It is worth noting that the heating temperature T1 can be continuously adjusted as the battery temperature T2 changes, or it can be adjusted periodically. In this embodiment, during the heating step, the heating temperature T1 is changed every first time interval. This first time interval is 45 min to 75 min, thereby reducing the sensitivity requirements of the equipment.
[0068] In this embodiment, the heating temperature T1 is adjusted every 1 hour, so the temperature curve of the heating temperature T1 shows a gradient change.
[0069] Furthermore, monitoring the battery temperature includes:
[0070] The internal temperature of the top, middle, and bottom of the battery is monitored.
[0071] By monitoring the temperature at multiple points on the battery, we can obtain more comprehensive internal temperature data, thereby ensuring that the local temperature of the battery does not exceed the baking temperature T0.
[0072] It's understandable that monitoring the internal temperature of a battery can be achieved by inserting a thermocouple inside. However, in actual production, this method is both time-consuming and labor-intensive, and it can also affect battery quality. Therefore, it's necessary to calibrate the temperature settings of the baking oven, using batteries of different sizes for testing, to calibrate the temperature rise curve of that type of battery under various parameters (the value of k, battery temperature, etc.). Then, in mass production, it's no longer necessary to monitor the battery temperature; the time can be calculated directly according to the corresponding curve.
[0073] After the heating step, a vacuuming step is required to remove the high-pressure gas from the baking chamber before proceeding with the baking process. During the baking process, the baking chamber is filled with a gas that is inert to the battery, and after a second time interval, the baking chamber is vacuumed again.
[0074] The purpose of baking is to dry the moisture in the battery. After evacuating the inside of the baking chamber, the moisture evaporates. Then, an inert gas (nitrogen in this embodiment) is introduced and maintained for a second time interval. After the water vapor and nitrogen mix, the mixed gas is extracted to ensure that the inside of the baking chamber is dry. The second time interval is 5 to 10 minutes.
[0075] After the third time interval, repeat the above operation until baking is complete, ensuring that the water vapor content in the baking cavity remains low throughout the baking process.
[0076] Because nitrogen filling and vacuuming are performed alternately, this baking mode is also called the breathing mode. The pressure of nitrogen gas injected into the baking chamber each time is 1 kPa to 3 kPa, and the third time interval is 50 min to 70 min.
[0077] Specifically, in the breathing mode, the pressure of nitrogen gas introduced into the baking chamber each time can be 1 kPa, 1.5 kPa, 2 kPa, 2.5 kPa or 3 kPa, and the third time interval can be 50 min, 55 min, 60 min, 65 min or 70 min.
[0078] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.
Claims
1. A method for baking a battery, characterized in that, include: Heating: The battery is heated to a baking temperature T0, the heating temperature T1 is higher than T0, and the heating temperature T1 decreases as the battery temperature T2 increases. Baking: The battery is baked at the baking temperature T0 and kept warm for a period of time; During the heating process of the battery, the heating temperature is controlled as T1 = k(T0 - T2) + T0; k≤0.2, and the maximum value of the heating temperature T1 is the baking temperature T0+15℃.
2. The battery baking method according to claim 1, characterized in that, In the heating step, the heating temperature T1 is changed every first time interval.
3. The battery baking method according to claim 1, characterized in that, The baking temperature T0 is in the range of 90℃~100℃.
4. The baking method for the battery according to any one of claims 1 to 3, characterized in that, Prior to the heating step, the following is also included: Gas filling: The baking chamber is evacuated and then filled with a gas that is inert to the battery.
5. The battery baking method according to claim 4, characterized in that, The gas that is inert to the battery is one of nitrogen, helium, and argon.
6. The baking method for the battery according to any one of claims 1 to 3, characterized in that, Following the heating step, the method further includes: Vacuuming is performed on the baking cavity before proceeding with the baking steps. The baking step also includes: The baking chamber is filled with a gas that is inert to the battery. After maintaining this for a second time interval, the baking chamber is evacuated. Repeat the above operation after the third time interval.
7. The baking method for the battery according to any one of claims 1 to 3, characterized in that, The baking method further includes: The temperature of the battery is monitored to ensure that the temperature of the battery is lower than the baking temperature T0.
8. The battery baking method according to claim 7, characterized in that, Monitoring the temperature of the battery includes: The internal temperature of the top, middle and bottom of the battery is monitored.