Charging and discharging performance test method and test equipment

Abstract

The embodiment of the invention provides a charging and discharging performance test method and test equipment, and relates to the technical field of battery charging and discharging. In the charging and discharging performance test method, the cell module is placed in the test box, and the test box is used for stabilizing temperature and humidity; connecting the positive and negative electrodes of the battery cell module with an input / output cable of test equipment; detecting the resistance between the input / output cable and the battery cell module, and judging whether the resistance between the input / output cable and the battery cell module is smaller than a first resistance threshold value or not; if yes, the test equipment charges and discharges the battery cell module through an input / output cable to obtain charging energy data and discharging energy data; and obtaining the energy efficiency according to the charging energy data and the discharging energy data. The resistors at important positions are controlled, so that test errors caused by over-high temperature generated by over-high resistance are avoided, and the accuracy of the initial charging and discharging energy efficiency test of the lithium battery is improved.

Description

Technical Field

[0001] The present application relates to the technical field of battery charging and discharging, and in particular to a charging and discharging performance testing method and testing equipment. Background Art

[0002] According to the national standard GB / T 36276-2023 for lithium-ion batteries for power energy storage, the initial charge and discharge performance of battery cells under rated power conditions should meet the following requirements: the initial charge and discharge energy efficiency at 25°C is not less than 93%. However, the current enterprise standards for energy storage systems require battery suppliers' products to meet the following requirements: the initial charge and discharge performance under rated power conditions should reach an initial charge and discharge energy efficiency at 25°C of not less than 94.5%.

[0003] Improving the energy efficiency of charging and discharging will improve energy utilization. High efficiency of charging and discharging means that waste in the energy conversion process will be reduced, thereby improving the overall energy benefit efficiency. The company's operating costs will also be greatly reduced, thereby improving the company's economic benefits.

[0004] However, the test results obtained by the existing methods for testing the initial charge and discharge energy efficiency have disadvantages such as instability, inaccurate results, and poor data reliability. Retesting batteries with abnormal test results will also increase testing costs and waste resources.

[0005] Therefore, how to improve the accuracy of initial charge and discharge energy efficiency testing of lithium batteries is a technical problem that needs to be solved. Summary of the invention

[0006] The purpose of the present application is to provide a charge and discharge performance test method and test equipment to solve the technical problem of how to improve the accuracy of initial charge and discharge energy efficiency testing of lithium batteries in the prior art.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions.

[0008] In a first aspect, an embodiment of the present application provides a charge and discharge performance testing method, comprising:

[0009] Provide battery cell modules;

[0010] Placing the battery cell module in a test box, wherein the test box is used to stabilize the temperature and humidity;

[0011] Connect the positive and negative electrodes of the battery module to the input and output cables of the test equipment;

[0012] Detecting the resistance between the input / output cable and the battery module, and determining whether the resistance between the input / output cable and the battery module is less than a first resistance threshold;

[0013] Connecting the positive and negative electrodes of the battery module to the test equipment through a voltage data acquisition line to form a voltage data acquisition loop;

[0014] When the resistance between the input / output cable and the battery module is less than a first resistance threshold, the test equipment charges and discharges the battery module through the input / output cable to obtain charging energy data and discharging energy data;

[0015] Energy efficiency is obtained based on the charging energy data and the discharging energy data.

[0016] Optionally, the step of providing a battery cell module includes:

[0017] Welding multiple single cells;

[0018] The resistance of each welding point of the single battery cell is measured to determine that the resistance of each welding point is less than a second resistance threshold.

[0019] Optionally, the second resistance threshold is less than or equal to 0.2 mΩ.

[0020] Optionally, the step of detecting the resistance between the input / output cable and the battery cell module includes:

[0021] The resistance between the input / output cable and the welding point in the battery cell module is detected to determine whether the resistance between the input / output cable and the welding point in the battery cell module is less than a first resistance threshold.

[0022] Optionally, the first resistance threshold is less than or equal to 0.08 mΩ.

[0023] Optionally, the step of charging and discharging the battery module by the test equipment through the input and output cables includes:

[0024] The battery module is charged to a first voltage threshold in a constant power manner, and then left to stand for a first time period, and the test equipment then discharges the battery module to a second voltage threshold in a constant power manner.

[0025] Optionally, the test equipment is cyclically executed to charge the battery cell module to a first voltage threshold in a constant power manner, then stand for a first period of time, and then discharge the battery cell module to a second voltage threshold in a constant power manner, to obtain multiple groups of data, each group of data including charging energy data and discharging energy data.

[0026] Optionally, the number of times that the test equipment charges the battery cell module to a first voltage threshold in a constant power manner, then stands for a first time, and the test equipment discharges the battery cell module to a second voltage threshold in a constant power manner is greater than or equal to 4;

[0027] The first duration is greater than or equal to 10 minutes.

[0028] Optionally, the charge-discharge performance testing method further includes:

[0029] Connecting the battery cell temperature sampling point to the test equipment via a temperature data sampling line to form a temperature data acquisition loop;

[0030] The temperature set in the test box is 25°C.

[0031] In a second aspect, an embodiment of the present application provides a test device, which is used to implement the charge and discharge performance test method of the first aspect.

[0032] Compared with the prior art, this application has the following beneficial effects:

[0033] The charge and discharge performance test method provided in the embodiment of the present application controls the resistance at important positions, avoids the test error caused by excessive resistance, and improves the accuracy of the initial charge and discharge energy efficiency test of the lithium battery. The results of the initial charge and discharge energy efficiency test of the lithium battery can also be stabilized by controlling the temperature and humidity. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, 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 application 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 paying creative work.

[0035] Figure 1 A schematic diagram of a voltage data acquisition line provided in an embodiment of the present application being connected close to an electrode of a battery cell module;

[0036] Figure 2 This is a schematic diagram of the voltage data acquisition line not being connected close to the electrodes of the battery cell module. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. The described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0039] In the description of this application, it should be noted that relational terms such as first and second, etc., are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations;

[0040] “Connection” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0041] The test results obtained by the existing methods for testing the initial charge and discharge energy efficiency have the disadvantages of instability, inaccurate results, poor data reliability, etc.

[0042] In order to overcome the above problems, the present application embodiment provides a charge and discharge performance test method, comprising:

[0043] Step A, providing a battery cell module;

[0044] Step B, placing the battery cell module in a test chamber, the test chamber is used to stabilize the temperature and humidity;

[0045] Step C, connecting the positive and negative electrodes of the battery module to the input and output cables of the test equipment;

[0046] Step D, detecting the resistance between the input / output cable and the battery module, and determining whether the resistance between the input / output cable and the battery module is less than a first resistance threshold; the first resistance threshold may be 0.08 mΩ, or a resistance value less than 0.08 mΩ;

[0047] Step E, connecting the positive and negative electrodes of the battery module to the test equipment through a voltage data acquisition line to form a voltage data acquisition loop;

[0048] Step F, when the resistance between the input / output cable and the battery module is less than a first resistance threshold, the test equipment charges and discharges the battery module through the input / output cable to obtain charging energy data and discharging energy data;

[0049] Step G, obtaining energy efficiency according to the charging energy data and the discharging energy data.

[0050] The steps of the charge and discharge performance test method are not limited in order, and the order can be interchanged if there is no conflict. For example, the cable connection can be performed first, and then the resistance detection and judgment can be performed, and then the battery module can be placed in the test box; or the battery module can be placed in the test box first, and then the cable connection can be performed, and then the resistance detection and judgment can be performed.

[0051] The input and output cables are an important part that affects the stability of the test results. The beneficial effect of this charge and discharge performance test method is that, by controlling the resistance at important positions, it avoids the test error caused by excessive resistance and excessive temperature, thereby improving the accuracy of the initial charge and discharge energy efficiency test of the lithium battery.

[0052] In step B, the temperature and humidity can be controlled to further stabilize the results of the initial charge and discharge energy efficiency test of the lithium battery and improve the accuracy of the initial charge and discharge energy efficiency test of the lithium battery.

[0053] Regarding the cell module of step A, the cell module may be provided in the following manner:

[0054] Step A.1, welding a plurality of single cells, and electrodes of the plurality of single cells form a bus;

[0055] Step A.2, measuring the resistance of each welding point of the single battery cell, and determining that the resistance of each welding point is less than a second resistance threshold.

[0056] The second resistance threshold may be 0.2 mΩ, or may be a resistance value less than 0.2 mΩ.

[0057] The beneficial effect of providing a battery cell module in this manner is that, since the welding points of the single battery cells will also affect the stability of the test results, by controlling the resistance of these welding points to be less than the second resistance threshold, the accuracy of the initial charge and discharge energy efficiency test of the lithium battery can be improved.

[0058] On the basis of providing the telecommunication module in a welding-based manner, the resistance between the input and output cables and the cell module in the above step D may be detected by detecting the resistance between the input and output cables and the welding points in the cell module. The first end of the input and output cables is connected to the test equipment, and the second end of the input and output cables is in contact with the welding points by bonding or other fixing methods. Then, detecting the resistance between the input and output cables and the welding points in the cell module can prevent the input and output cables and the welding points in the cell module from being loosely fitted, having too small a contact area, or even having an air gap, which may lead to a large resistance. It ensures that the resistance from the input and output cables to the welding points in the cell module is less than the first resistance threshold, thereby improving the accuracy of the initial charge and discharge energy efficiency test of the lithium battery.

[0059] In step E, other signal acquisition line connection operations may also be added, such as temperature signal acquisition. Step E may also include connecting the battery cell temperature sampling point with the test equipment through a temperature data sampling line to form a temperature data acquisition loop, which can monitor the temperature, and may also add a heater, fan and other devices to control the temperature. Current acquisition can be completed through input and output cables.

[0060] The temperature in the test chamber is set at 25°C. It is possible to further monitor whether the temperature in the test chamber is within a range of about 25°C. If so, the test is accurate. If not, the temperature may need to be intervened. A range of about 25°C can be 5°C to 45°C.

[0061] The beneficial effect of setting the temperature in the test chamber to 25°C is that the stable temperature can stabilize the battery charging and discharging performance, thereby improving the accuracy of the battery's initial charging and discharging energy efficiency test.

[0062] In step E, the voltage data acquisition line is connected to the position closest to the positive and negative pole terminals to collect the voltage, such as Figure 1 The positive electrode of the battery cell module is connected to a metal plate, and the negative electrode is connected to a metal plate of the same shape. The metal plate is stepped and has three parts. The first part of the metal plate is horizontal and close to the positive or negative electrode, the second part is bent upward and perpendicular to the first part, and the third part is horizontal and extends outward. The voltage collection line should be connected to the first part of the metal plate.

[0063] In other embodiments, the metal plate connected to the positive and negative electrodes of the battery cell module may have two parts, the first part is close to the positive electrode or the negative electrode, the first part is close to the surface of the battery cell module, and the second part does not touch the surface of the battery cell module, and the second part extends outward, then the voltage data acquisition line is connected to the first part of the metal plate.

[0064] Figure 2 An opposite implementation method is shown, in which the positive electrode of the battery cell module is connected to a metal plate, and the negative electrode is connected to a metal plate of the same shape. The metal plate is stepped and has three parts. The first part of the metal plate is horizontal and close to the positive or negative electrode, the second part is bent upward and perpendicular to the first part, and the third part is horizontal and extends outward. The voltage collection line is connected to the third part, but because the third part is far away from the electrode of the battery cell module and has a large resistance, it will have an adverse effect on the stability of the test, so this method should be avoided.

[0065] In step F, the process of charging and discharging the battery cell module by the test equipment through the input and output cables may include: charging the battery cell module to a first voltage threshold in a constant power manner, then standing for a first period of time, and the test equipment then discharging the battery cell module to a second voltage threshold in a constant power manner.

[0066] Regarding the first duration of standing still, the first duration may be 10 minutes, or a duration greater than 10 minutes.

[0067] The beneficial effect of setting this resting process is that the resting process can make the inside of the battery tend to be stable, and then the subsequent discharge process will be stable.

[0068] In step F, the process in which the test equipment charges and discharges the battery cell module through the input and output cables may include multiple charge and discharge cycles, that is, the test equipment charges the battery cell module to a first voltage threshold in a constant power manner, then stands for a first period of time, and the test equipment then discharges the battery cell module to a second voltage threshold in a constant power manner, thereby obtaining multiple groups of data, each group of data including charging energy data and discharging energy data.

[0069] The beneficial effect of multiple charge and discharge cycle tests is that more data can be obtained, and statistical methods such as average values ​​can be used to avoid the impact of a single test result with a large accidental error on the evaluation of the battery module.

[0070] In step F, a certain time interval may be provided between each two charge and discharge cycles of the multiple charge and discharge cycles, that is, after the test equipment discharges the battery cell module to the second voltage threshold at a constant power, the battery cell module may be left to stand for a second time, and then the battery cell module may be charged to the first voltage threshold at a constant power for the next time.

[0071] Regarding the second duration of standing still, the second duration may be 10 minutes, or a duration greater than 10 minutes.

[0072] The beneficial effect of setting this resting process is that the resting process can make the inside of the battery tend to be stable, and thus the performance is stable in the next charging process.

[0073] Regarding the number of multiple charge and discharge cycles, the number of multiple charge and discharge cycles can be set to 4 times, or the number of multiple charge and discharge cycles can be set to a number greater than 4 times.

[0074] The beneficial effect of setting the number of multiple charge and discharge cycles to be greater than or equal to 4 times is that 4 cycles can better avoid the impact of a test result with a large accidental error on the evaluation of the battery module.

[0075] In order to verify the beneficial effect of the present charge and discharge performance test method through comparison, in a comparative test, the same batch of 314Ah LFP lithium-ion batteries of the same specifications were divided into two groups for charge and discharge performance tests. The first and second durations of the two groups of tests were both 10 minutes, the first voltage threshold was 3.65V, and the second voltage advance was 2.5V. The difference was that the second group used 0.2mΩ as the second resistance threshold of the welding point resistance, and 0.08mΩ as the first resistance threshold of the resistance between the welding point and the input and output cables; the first group did not limit the resistance. The energy efficiency data obtained by the two groups are compared in the following table:

[0076]

[0077] By comparing the test results, it can be seen that the battery charging and discharging energy efficiency measured by this charging and discharging performance test method is high and has good consistency; the test data is reliable and the test cost is low, which is beneficial for enterprises to improve test efficiency and product test reliability.

[0078] Based on the above embodiment, the embodiment of the present application also provides a test device, which is used to implement the above charge and discharge performance test method. The test equipment may include multiple types, each of which corresponds to certain parameter conditions, and the parameter conditions may be test temperature, humidity, battery size, voltage, power and other parameters. In the charge and discharge performance test method, the test equipment can be selected according to the test parameter conditions.

[0079] In general, this application proposes a charge and discharge performance test method and test equipment, which can be tested according to the requirements of the national standard GB / T 36276-2023 version of lithium-ion batteries for power energy storage, so that the test results are stable and reliable, so that batteries that originally do not meet the requirements of the enterprise standard of the energy storage system end that "the initial charge and discharge performance under rated power conditions reaches an initial charge and discharge energy efficiency of not less than 94.5% under 25°C" can meet this requirement, improve the original problems of long production and R&D cycles and high corporate economic costs, and achieve higher corporate economic benefit goals.

[0080] In addition, this charge and discharge performance test method has good accuracy and does not require too many retests, thus saving test costs.

[0081] The above-described device and system embodiments are merely illustrative, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. A person skilled in the art may understand and implement the present embodiment without creative effort.

[0082] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A charge and discharge performance testing method, characterized in that: include: Provide battery cell modules; Placing the battery cell module in a test box, wherein the test box is used to stabilize the temperature and humidity; Connect the positive and negative electrodes of the battery module to the input and output cables of the test equipment; Detecting the resistance between the input / output cable and the battery module, and determining whether the resistance between the input / output cable and the battery module is less than a first resistance threshold; Connecting the positive and negative electrodes of the battery module to the test equipment through a voltage data acquisition line to form a voltage data acquisition loop; When the resistance between the input / output cable and the battery module is less than a first resistance threshold, the test equipment charges and discharges the battery module through the input / output cable to obtain charging energy data and discharging energy data; Energy efficiency is obtained based on the charging energy data and the discharging energy data.

2. The charge and discharge performance testing method according to claim 1, characterized in that: The steps of providing a cell module include: Welding multiple single cells; The resistance of each welding point of the single battery cell is measured to determine that the resistance of each welding point is less than a second resistance threshold.

3. The charge and discharge performance testing method according to claim 2, characterized in that: The second resistance threshold is less than or equal to 0.2 mΩ.

4. The charge and discharge performance testing method according to claim 2, characterized in that: The step of detecting the resistance between the input / output cable and the battery cell module comprises: The resistance between the input / output cable and the welding point in the battery cell module is detected to determine whether the resistance between the input / output cable and the welding point in the battery cell module is less than a first resistance threshold.

5. The charge and discharge performance testing method according to claim 4, characterized in that: The first resistance threshold is less than or equal to 0.08 mΩ.

6. The charge and discharge performance testing method according to claim 1, characterized in that: The step of charging and discharging the battery module by the test equipment through the input and output cables comprises: The battery module is charged to a first voltage threshold in a constant power manner, and then left to stand for a first time period, and the test equipment then discharges the battery module to a second voltage threshold in a constant power manner.

7. The charge and discharge performance testing method according to claim 6, characterized in that: The test equipment is cyclically executed to charge the battery cell module to a first voltage threshold in a constant power manner, and then stand for a first period of time, and the test equipment then discharges the battery cell module to a second voltage threshold in a constant power manner, to obtain multiple groups of data, each group of data including charging energy data and discharging energy data.

8. The charge and discharge performance testing method according to claim 7, characterized in that: The number of times that the test equipment charges the battery module to a first voltage threshold in a constant power manner, then leaves the battery module to rest for a first time, and then discharges the battery module to a second voltage threshold in a constant power manner is greater than or equal to 4; The first duration is greater than or equal to 10 minutes.

9. The charge and discharge performance testing method according to claim 1, characterized in that: The charge and discharge performance testing method further comprises: Connecting the battery cell temperature sampling point to the test equipment via a temperature data sampling line to form a temperature data acquisition loop; The temperature set in the test box is 25°C.

10. A test device, characterized in that: The test equipment is used to implement the charge and discharge performance test method according to any one of claims 1 to 9.

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