Method and device for measuring surface heat dissipation coefficient of lithium battery

Abstract

The invention provides a method and a device for measuring the surface heat dissipation coefficient of a lithium battery shell. The method comprises the following steps: obtaining the lithium battery shell; after liquid is added into the lithium battery shell, the lithium battery shell is placed in a detection environment at a constant temperature Th; after the liquid and the lithium battery shell reach heat transfer balance, the time t corresponding to the liquid reduced by the preset temperature delta T and the temperature Tk1 of the outer surface of the lithium battery shell at at least one moment are obtained respectively; and obtaining the surface heat dissipation coefficient hk of the lithium battery shell according to a formula # imgabs0 #.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium battery performance testing, and relates to a method and a device for measuring the surface heat dissipation coefficient of a lithium battery. Background Art

[0002] With the widespread application of lithium batteries in various fields, such as electric vehicles and mobile electronic devices, thermal management of lithium batteries has become crucial. Lithium batteries generate heat during the charging and discharging process. If the heat cannot be dissipated in time, the battery temperature will rise, which will affect the performance and life of the battery and even bring safety hazards. The heat dissipation coefficient of the lithium battery surface is one of the key parameters in thermal management design.

[0003] Currently, there are few existing methods for measuring the surface heat dissipation coefficient of lithium batteries, and some of them have problems such as low accuracy, complex operation, or failure to simulate actual working conditions well, resulting in most experiments and engineering applications relying solely on experience. Summary of the invention

[0004] The present invention provides a method and device for measuring the heat dissipation coefficient of the surface of a lithium battery, which can effectively solve the above-mentioned problem.

[0005] The present invention is achieved in that:

[0006] In one aspect, the present invention provides a method for measuring the surface heat dissipation coefficient of a lithium battery, the method comprising:

[0007] Obtain a lithium battery shell;

[0008] After adding liquid into the lithium battery shell, the lithium battery shell is placed at a constant temperature T h Under the testing environment;

[0009] After the liquid and the lithium battery shell reach heat transfer equilibrium, respectively obtain the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment;

[0010] According to the formula: Get the heat dissipation coefficient h of the lithium battery shell surface k ,

[0011] Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

[0012] In another aspect, the present invention provides a device for measuring the surface heat dissipation coefficient of a lithium battery, the device comprising:

[0013] Constant temperature module, used to provide a constant temperature T h A detection environment is provided, a lithium battery shell is obtained, and after adding liquid into the interior of the lithium battery shell, the lithium battery shell is placed at a constant temperature T provided by the constant temperature module. h Under the testing environment;

[0014] A measuring module, for obtaining the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment after the liquid and the lithium battery shell reach heat transfer equilibrium;

[0015] Processing module, used according to the formula: Get the heat dissipation coefficient h of the lithium battery shell surface k ,

[0016] Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

[0017] The beneficial effects of the present invention are:

[0018] The present invention provides a method for measuring the surface heat dissipation coefficient of a lithium battery. During the measurement, the temperature changes of the inner and outer surfaces of a lithium battery shell during the heat dissipation process are accurately grasped, and the ambient temperature is detected, so that the surface heat dissipation coefficient of the lithium battery can be measured more accurately.

[0019] Furthermore, the measuring device used in the measuring process is simple and easy to obtain, the measuring method has simple steps, strong operability, and can obtain reliable intermediate measurement data, thereby ensuring the accuracy of the obtained lithium battery surface heat dissipation coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 It is a flow chart of a method S100 for measuring the surface heat dissipation coefficient of a lithium battery provided in an embodiment of the present disclosure.

[0022] Figure 21 is a first structural schematic diagram of an apparatus 1000 for measuring a surface heat dissipation coefficient of a lithium battery provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0024] The embodiment of the present invention provides a method S100 for measuring the surface heat dissipation coefficient of a lithium battery.

[0025] Specifically, Figure 1 As shown, the method S100 includes:

[0026] S102, obtaining a lithium battery shell.

[0027] In some embodiments, the lithium battery shell has a prismatic or cylindrical shape.

[0028] Disassemble the lithium battery and take out the internal battery cell. Keep the battery shell size of the lithium battery consistent during disassembly to avoid measurement errors caused by size as much as possible.

[0029] The disassembly method may specifically be to remove the upper cover from the battery case so as to take out the internal battery cells and add the liquid in step S2.

[0030] The length, width, height and other parameters of the battery shell are measured with a caliper, and then the surface area A of the battery shell is calculated.

[0031] S104, after adding liquid into the lithium battery shell, the lithium battery shell is placed at a constant temperature T h under the testing environment.

[0032] The added liquid needs to fill the internal space of the shell to avoid the presence of air, because the air may flow out of the shell during the subsequent measurement process, taking away some heat and affecting the accuracy of the measurement.

[0033] In some embodiments, the liquid is water.

[0034] In some other embodiments, the liquid may be oil, specifically heat transfer oil.

[0035] Compared with aqueous solutions of oils, inorganic salts or organic salts, water has a larger specific heat capacity and has a good heat storage capacity.

[0036] In the measurement process of the embodiment of the present invention, if the density difference is not taken into account, and the same mass of water and oil are used for measurement (after the liquid and the lithium battery shell reach heat transfer equilibrium), the temperature of the liquid is the same at the initial moment and is higher than the detection ambient temperature. Heat is dissipated through the same battery shell. Since water has a larger specific heat capacity, it transfers more heat when it is reduced by 1°C, and the time required is longer.

[0037] The specific heat capacity of the appropriate liquid may be selected according to the design of the measurement experiment, for example, based on other relevant parameters such as the determined temperature of the added liquid, the detection environment temperature, etc., thereby selecting the type of liquid.

[0038] On the other hand, the liquid also needs to have good thermal conductivity, that is, thermal conductivity, so as to achieve uniform internal temperature and avoid the liquid temperature far away from the inner surface of the battery shell and the liquid temperature in contact with the inner surface of the battery shell being unable to effectively reach equilibrium.

[0039] In terms of thermal conductivity, water can also be used as a preferred option.

[0040] An 8-channel temperature detector was used to measure the temperature.

[0041] Before adding liquid, connect the 8-channel temperature detector to the disassembled battery shell, and stick channels 1, 3, and 5 to the upper, middle, and lower positions of the inner surface of the battery shell, and to the upper, middle, and lower positions of the outer surface of the battery shell. Channels 7 and 8 are fixed at different positions in the detection environment, such as the opposite sides of the battery shell, and keep a certain distance from the battery shell.

[0042] After adding the liquid, put the top cover on to make the battery shell as closed as possible to avoid air exchange between the inside and the outside.

[0043] Turn on the 8-channel temperature detector to record temperature data.

[0044] The data recorded from channel 1 to channel 8 are recorded as T1 to T8 respectively, and the temperature of the liquid at each moment can be obtained. Battery case outer surface temperature Detection environment temperature

[0045] In some embodiments, the detection environment temperature is 0-45°C.

[0046] After the liquid and the lithium battery shell reach heat transfer equilibrium, when the test environment temperature is lower and other conditions are the same, the outer surface of the battery shell has a faster heat dissipation speed, which can reduce the measurement time. The test environment temperature of 0-45℃ is selected to simulate the surface heat dissipation of the lithium battery at the temperature of its normal operating environment, so that the surface heat dissipation coefficient is more in line with the actual working value of the lithium battery, improving the practicality of the data.

[0047] In some embodiments, the detection environment temperature is 20-30° C. The detection environment temperature is further defined as the optimal operating temperature of the lithium battery.

[0048] In some embodiments, placing the lithium battery shell in a testing environment includes: the testing environment is an environment of a constant temperature box.

[0049] The environment of the thermostat box maintains a constant temperature while having a relatively smooth air flow, which can speed up the heat dissipation of the battery shell surface without affecting the stability of the measurement and causing a large difference from the actual working environment.

[0050] S106, after the liquid and the lithium battery shell reach heat transfer equilibrium, respectively obtain the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment.

[0051] S108, according to the formula: Get the heat dissipation coefficient h of the lithium battery shell surface k ,

[0052] Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

[0053] The principle of the formula:

[0054] When an object is placed in the outside world, if its temperature is higher than the outside temperature, there is a temperature difference between the surface temperature and the outside world, and surface heat dissipation will occur.

[0055] In the method, during the thermal equilibrium process, without considering the cooling of the battery shell, only the cooling of the liquid generates heat, and there is no other reaction, so the heat released by the liquid is equal to the heat dissipated by the outer surface of the battery shell.

[0056] According to the thermodynamic formula Q 释放 =C×m×ΔT and Newton's heat dissipation formula Q 表面散热 =A×h×ΔT, the surface heat dissipation coefficient h of the battery shell can be calculatedk .

[0057] In some embodiments, in step S2, the lithium battery shell is placed in a constant temperature detection environment, and then the temperature measurement is started after 1 minute.

[0058] Generally, within 1 minute, the liquid and the lithium battery shell can reach a heat transfer equilibrium without causing too much heat loss.

[0059] First of all, it should be pointed out that the temperature T of the outer surface of the battery shell k Need to be greater than the detection environment temperature T h To achieve surface heat dissipation.

[0060] Furthermore, C y m y (T0-T h )>C k m k (T p -T e ), C y is the specific heat capacity of the liquid, m y is the mass of the liquid added to the battery case, C k is the specific heat capacity of the battery shell, m k is the mass of the battery shell, T0 is the temperature when the liquid is added to the battery shell and no heat transfer occurs with the battery shell, T h To detect the ambient temperature, T p It is the temperature at the initial moment when the liquid and the lithium battery shell reach heat transfer equilibrium.

[0061] When the liquid and the lithium battery shell reach heat transfer equilibrium, the inner and outer surfaces of the lithium battery shell reach heat transfer equilibrium at the same time.

[0062] In some embodiments, the time t corresponding to the liquid lowering a predetermined temperature ΔT is respectively obtained, including: t is not less than 200 s.

[0063] The numerical accuracy of the formula for obtaining the time t is one of the factors affecting the accuracy of the calculation results.

[0064] Selecting a duration of not less than 200 s can reduce errors caused by instrument measurement accuracy.

[0065] However, for the sake of simplicity in calculation, the heat dissipation coefficient of the lithium battery shell surface h k The average value within the time period t is used. If the time period is too long, it will affect the accuracy of the measurement and cause the result to be smaller.

[0066] Moreover, if the duration is too long, it means that the temperature difference of surface heat dissipation is small, which is also not conducive to the accuracy of measurement.

[0067] In some embodiments, the liquid is lowered to a predetermined temperature ΔT, comprising: T y1 -T h =54-56°C, where T y1 The temperature of the liquid at the initial moment corresponding to the predetermined temperature ΔT is lowered for the liquid.

[0068] The temperature difference of surface heat dissipation is small, which may result in the inability to accurately display temperature data through the instrument, which is not conducive to the accuracy of measurement.

[0069] However, too large a temperature difference will shorten the measurement time.

[0070] In determining the detection environment temperature T h Then, select the liquid temperature T at which the measurement starts. y1 The numerical value of is another major factor affecting the accuracy of the calculation results of the formula, and the above two factors are related.

[0071] The temperature of the liquid at the start of the measurement T y1 What is affected is the speed at which the surface dissipates heat.

[0072] In some embodiments, the liquid is cooled by a predetermined temperature ΔT, including: ΔT = 2-10°C.

[0073] For the simplicity of calculation, the heat dissipation coefficient of the lithium battery shell surface h k The average within the time t is used, and ultimately, it is the average within the process of reducing the predetermined temperature ΔT.

[0074] Therefore, if the predetermined temperature ΔT is too large, the temperature difference of the surface heat dissipation may be small, which may affect the accuracy of the measurement and cause the result to be too small.

[0075] The reason why a temperature difference less than 2°C is not selected is also due to consideration of instrument measurement accuracy.

[0076] The size of the predetermined temperature ΔT determines the amount of heat dissipated from the surface.

[0077] The mass of the liquid m y This can be measured on a balance, for example by subtracting the mass of the empty battery case from the mass of the liquid and the empty battery case.

[0078] In some embodiments, obtaining the temperature of the outer surface of the lithium battery shell at at least one moment corresponding to the liquid being lowered by a predetermined temperature ΔT comprises:

[0079] Get the temperature T of the outer surface of the lithium battery shell at the initial moment when the liquid drops a predetermined temperature ΔT k1 The temperature T of the outer surface of the lithium battery shell at the end k2 .

[0080]

[0081] In some embodiments, the detected ambient temperature T at the initial moment corresponding to the liquid dropping a predetermined temperature ΔT is obtained. h1 And the end time detection ambient temperature T h2 .

[0082]

[0083] The method provided by the embodiment of the present invention can more accurately measure the surface heat dissipation coefficient h of the lithium battery. k To meet the thermal management needs of lithium batteries during R&D, production and application, including:

[0084] 1. Better understand the heat exchange between lithium batteries and the surrounding environment during operation. For example, when designing a battery cooling system, an accurate surface heat dissipation coefficient can help engineers determine the appropriate cooling method and parameters such as the flow rate of the cooling medium, thereby effectively preventing the battery from overheating and extending the battery life.

[0085] 2. Improve the safety of lithium batteries. Batteries may burn, explode, or cause serious accidents when they are overheated. By clearly understanding the surface heat transfer coefficient, you can predict the temperature change trend of the battery, take measures in advance to avoid dangerous temperatures, and ensure the safety of the battery during use.

[0086] 3. It is conducive to improving the accuracy of lithium battery performance evaluation. Battery performance is closely related to temperature. By measuring the surface heat transfer coefficient to accurately analyze the thermal behavior of the battery, the actual performance of the battery under different working conditions, such as charging and discharging efficiency, can be more accurately evaluated.

[0087] An embodiment of the present invention provides a device 1000 for measuring the surface heat dissipation coefficient of a lithium battery.

[0088] The device may include a corresponding module for performing each or several steps in the above flowchart. Therefore, each step or several steps in the above flowchart may be performed by a corresponding module, and the device may include one or more modules in these modules. The module may be one or more hardware modules specially configured to perform the corresponding steps, or implemented by a processor configured to perform the corresponding steps, or stored in a computer-readable medium for implementation by a processor, or implemented by some combination.

[0089] Specifically, Figure 2 As shown, the device 1000 includes:

[0090] Constant temperature module 1002, used to provide a constant temperature T hA detection environment is provided, a lithium battery shell is obtained, and after adding liquid into the interior of the lithium battery shell, the lithium battery shell is placed at a constant temperature T provided by the constant temperature module. h Under the testing environment;

[0091] The measuring module 1004 is used to obtain the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment after the liquid and the lithium battery shell reach heat transfer equilibrium;

[0092] The processing module 1006 is used to calculate the following formula: Get the heat dissipation coefficient h of the lithium battery shell surface k ,

[0093] Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

[0094] Among them, the hardware structure adopted by the abnormal source node search device in the LoRa tree network based on the hardware implementation of the processor disclosed in the present invention can be implemented using a bus architecture. The bus architecture can include any number of interconnected buses and bridges, depending on the specific application and overall design constraints of the hardware. The bus connects various circuits including one or more processors, memories and / or hardware modules together. The bus can also connect various other circuits such as peripherals, voltage regulators, power management circuits, external antennas, etc.

[0095] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Component (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one connecting line is used in this figure, but it does not mean that there is only one bus or one type of bus.

[0096] Any process or method description in the flowchart or otherwise described herein can be understood as a module, fragment or portion of a code representing one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present disclosure includes other implementations, in which the functions may not be performed in the order shown or discussed, including performing the functions in a substantially simultaneous manner or in a reverse order according to the functions involved, which should be understood by a person skilled in the art of the present disclosure. The processor performs the various methods and processes described above. For example, the method implementation in the present disclosure can be implemented as a software program, which is tangibly contained in a machine-readable medium, such as a memory. In some embodiments, part or all of the software program can be loaded and / or installed via a memory and / or a communication interface. When the software program is loaded into the memory and executed by the processor, one or more steps in the method described above can be performed. Alternatively, in other embodiments, the processor can be configured to perform one of the above methods in any other appropriate manner (e.g., by means of firmware).

[0097] The logic and / or steps represented in the flowchart or otherwise described herein may be embodied in any readable storage medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch instructions from and execute instructions on an instruction execution system, apparatus, or device), or in combination with such instruction execution systems, apparatuses, or devices.

[0098] For the purposes of this specification, a "readable storage medium" may be any device that can contain, store, communicate, propagate or transmit a program for use with or in conjunction with an instruction execution system, device or apparatus. More specific examples of readable storage media (a non-exhaustive list) include the following: an electrical connection with one or more wirings (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and editable read-only memory (EPROM or flash memory), a fiber optic device, and a portable read-only memory (CDROM). In addition, the readable storage medium may even be paper or other suitable medium on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a memory.

[0099] It should be understood that the various parts of the present disclosure can be implemented in hardware, software, or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented in software stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0100] A person skilled in the art may understand that all or part of the steps of implementing the above-mentioned implementation method may be completed by instructing related hardware through a program, and the program may be stored in a readable storage medium, which, when executed, includes one or a combination of the steps of the implementation method.

[0101] In addition, each functional unit in each embodiment of the present disclosure may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a readable storage medium. The storage medium may be a read-only memory, a disk or an optical disk, etc.

[0102] Example 1

[0103] The surface heat dissipation coefficient of a group of lithium battery shells was measured using the method described in the embodiment of the present invention.

[0104] The shape of the lithium battery shell is cubic. After measurement, the area A of the outer surface of the lithium battery shell is k =0.121m 2 .

[0105] Use hot water at about 85°C. The specific heat capacity of the water is C y =4200J / kg·K.

[0106] The mass of hot water added is measured to be m y =2.75kg.

[0107] A constant temperature box with a preset temperature of 27°C was used.

[0108] The temperature of the added hot water is about 85°C.

[0109] The temperature was measured using a Tesco TK4708 8-channel temperature detector, which recorded temperature data every 5 seconds.

[0110] Experiment 1

[0111] Select the temperature of the liquid at the initial moment T y1 The lithium battery surface heat dissipation coefficient h is calculated based on the data at 83.0, 82.5, 82.1, 81.7 and 81.3. k Calculation.

[0112] The measured data are shown in Table 1.

[0113] Table 1 Measured and calculated data

[0114]

[0115]

[0116] Among them, T y2 The temperature of the liquid at the end time corresponding to the predetermined temperature ΔT is lowered for the liquid. ΔT = T y1 -T y2 .

[0117] As can be seen from Table 1, the experiment selected the same initial temperature of the liquid.

[0118] When ΔT = 1.5°C, although h k The average value is close to that when ΔT = 2°C and ΔT = 10°C, and the relative deviation is less than 0.5%, but its variance is greater than 0.1. At this time, the time t is less than 200s, which cannot effectively reduce the measurement error caused by the instrument.

[0119] After calculation, when ΔT=1℃, h k The fluctuation is even greater.

[0120] When ΔT = 12°C, although h k The variance is small, but the relative deviation of its average value from that when ΔT=2℃ is greater than 0.5%.

[0121] Experiment 2

[0122] Select ΔT=10℃, T y2 The surface heat dissipation coefficient h of the lithium battery is calculated based on the data at 71.0, 70.9, 70.8, 70.7 and 70.6. k Calculation.

[0123] The measured data are shown in Table 2.

[0124] Table 2 Measured and calculated data

[0125]

[0126] It can also be seen from Table 2 that when T y2 ≤70.8℃, i.e. Ty1 -T h <54℃, three groups h k When ΔT=2℃h k The relative deviations of the mean values ​​were all greater than 0.5%.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for measuring the surface heat dissipation coefficient of a lithium battery, characterized in that: The method comprises: Obtain a lithium battery shell; After adding liquid into the lithium battery shell, the lithium battery shell is placed at a constant temperature T h Under the testing environment; After the liquid and the lithium battery shell reach heat transfer equilibrium, respectively obtain the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment; According to the formula: Get the heat dissipation coefficient h of the lithium battery shell surface k , Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

2. The method according to claim 1, characterized in that The liquid is water.

3. The method according to claim 1, placing the lithium battery shell under a testing environment, comprising: The detection environment is a constant temperature box environment.

4. The method according to claim 1, wherein the detection environment temperature is 20-30°C.

5. The method according to claim 1, wherein the time t corresponding to the liquid temperature decreasing by a predetermined temperature ΔT is obtained respectively, comprising: t is not less than 200s.

6. The method according to claim 1, characterized in that The liquid is cooled to a predetermined temperature ΔT, including: T y1 -T h =54-56°C, where T y1 The temperature of the liquid at the initial moment corresponding to the predetermined temperature ΔT is lowered for the liquid.

7. The method according to claim 1, characterized in that The liquid temperature is lowered by a predetermined temperature ΔT, including: ΔT = 2-10°C.

8. A device for measuring the heat dissipation coefficient of a lithium battery surface, characterized in that: The device comprises: Constant temperature module, used to provide a constant temperature T h A detection environment is provided, a lithium battery shell is obtained, and after adding liquid into the interior of the lithium battery shell, the lithium battery shell is placed at a constant temperature T provided by the constant temperature module. h Under the testing environment; A measuring module, for obtaining the time t corresponding to the liquid dropping a predetermined temperature ΔT and the temperature of the outer surface of the lithium battery shell at at least one moment after the liquid and the lithium battery shell reach heat transfer equilibrium; Processing module, used according to the formula: Get the heat dissipation coefficient h of the lithium battery shell surface k , Among them, C y is the specific heat capacity of the liquid, m y is the mass of the liquid, A k is the outer surface area of ​​the lithium battery shell, n represents n moments in time t, n ≥ 1, T kn is the temperature of the outer surface of the lithium battery shell at the nth moment.

Images