Series-parallel connection combination method for soft package energy storage device

Abstract

The invention discloses a series-parallel combination method for soft package energy storage devices in the field of high-power batteries, which comprises the following steps of: during series connection, ensuring that the voltage range of each soft package energy storage device on a series branch is 0-10mV; and during parallel connection, the capacity range of parallel branches is ensured to be 0-15mAh. According to the soft package energy storage device group, through series-parallel connection combination regulation and control, the voltage consistency of the series connection energy storage device and the consistency of the parallel branch capacity, internal resistance and the like are ensured, and the overall performance of the soft package energy storage device group is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of high-power batteries, and in particular relates to a series-parallel combination method of soft-pack energy storage devices. Background Art

[0002] With the development of society and the increasing demand for energy, research on energy storage device combination optimization technology has been promoted. In order to meet the requirements of different application scenarios for energy density, power density, cycle life and other aspects, improving the overall performance of energy storage devices through series-parallel combination optimization has become a key approach. Optimizing series-parallel combinations can reduce costs to a certain extent, for example, by reasonably matching energy storage devices with different performances to achieve improved cost performance. Summary of the invention

[0003] The present invention aims to provide a series-parallel combination method of soft-pack energy storage devices to improve the overall performance of a soft-pack energy storage device group.

[0004] A series-parallel combination method of soft-pack energy storage devices in this scheme includes the following steps: when connected in series, ensure that the voltage range of each soft-pack energy storage device in the series branch is 0-10mV; when connected in parallel, ensure that the capacity range of the parallel branch is 0-15mAh. The series-parallel combination regulation ensures that the voltage of the series energy storage devices is consistent, and the capacity and internal resistance of the parallel branches are consistent. The ultimate regulation of the minimum difference between the single voltage, capacity, and internal resistance of the soft-pack energy storage device.

[0005] Furthermore, when connected in series, ultrasonic welding is used to connect the positive and negative tabs of the soft-pack energy storage device together to form a series branch. With this processing method, no connector is introduced in the series connection, and the series connection length is determined by the positive and negative tabs of the energy storage device, so the effective connection width is constant, and the contact resistance and the metal resistance at the connection are basically constant.

[0006] Furthermore, when welding in series, use a straight groove fixture to fix the soft package energy storage device. Ensure that the connection is straight (avoid skew) and keep the connection width basically consistent.

[0007] Furthermore, when connected in parallel, laser welding of nickel strips is used to achieve parallel connection between multiple series branches. Nickel strip welding is used in parallel. Since the distance between parallel soft-pack energy storage devices is basically the same, the length of the nickel strip on each parallel branch is consistent, and the resistance value introduced by the parallel branch can also be consistent. By using ultrasonic welding in series and nickel strip welding in parallel, the line resistance distribution of the series-parallel combination of soft-pack energy storage devices is more uniform.

[0008] Furthermore, when there are a large number of soft-pack energy storage devices in series and in parallel, a folding and then stacking method is adopted, that is, the series and parallel connections are first laid flat, and then folded and laid flat on the surface of the lower soft-pack energy storage device.

[0009] Furthermore, the soft-pack energy storage device is a lithium-ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a structural schematic diagram of a method for combining soft-pack energy storage devices in series and parallel according to Embodiment 1 of the present invention;

[0011] Figure 2 It is a structural schematic diagram of the series connection branch of the ultrasonic welding series connection unit;

[0012] Figure 3 It is a schematic diagram of the structure of the parallel branch of the laser welding parallel unit;

[0013] Figure 4 It is a structural schematic diagram of the processing method when the number of soft-pack energy storage devices connected in series and in parallel is large;

[0014] Figure 5 This is a comparison chart of the capacity of energy storage device modules;

[0015] Figure 6 This is a comparison chart of the voltage at the end of charging and the voltage at the end of discharging of the energy storage device module;

[0016] Figure 7 This is a comparison chart of the cyclic discharge performance of energy storage device modules. DETAILED DESCRIPTION

[0017] The following is further described in detail through specific implementation methods:

[0018] Embodiment 1 is basically as attached Figures 1 to 3 As shown: A method for series-parallel combination of soft-pack energy storage devices, comprising the following steps:

[0019] Step 1: When connected in series, ensure that the voltage of the soft-pack energy storage device is basically consistent (the range is controlled within 10mV); when connected in parallel, to ensure that the capacity of the parallel branch () is basically consistent, you can freely combine them. Figure 1 As shown, if the capacity of the first parallel branch is greater than that of the second parallel branch, the soft-pack energy storage device with higher capacity is exchanged with the soft-pack energy storage device with lower capacity. If the branch capacities differ greatly after the exchange, the exchange can continue. This exchange is not limited to adjacent parallel branches, and can be exchanged every few branches until the capacities of each branch are basically equal (or controlled within a certain capacity range, such as 15mAh). After the capacity combination, the accumulation of the higher capacity of the soft-pack energy storage device on a certain branch, which makes the total capacity of the branch much higher than that of other branches, is eliminated.

[0020] Step 2: For the soft-pack energy storage device after the combination optimization, use ultrasonic welding to connect the positive and negative pole ears together to form a series branch. Before welding, use a straight groove fixture to fix the soft-pack energy storage device to prevent the series branch from bending after welding, such as Figure 2 As shown;

[0021] Step 3: After the series branch is completed, the nickel strip is laser welded for parallel connection (such as Figure 3 As shown); For the case where the number of series and parallel connections is large, the form of folding and then stacking can be adopted, that is, first laying the series and parallel connections flat, and then folding and laying them flat on the surface of the lower soft-pack energy storage device, such as Figure 4 shown.

[0022] Comparative experiment: 1.5Ah energy storage devices were selected, and then the patented method (method of Example 1) and the conventional method (direct assembly after screening of soft-pack energy storage devices) were used to assemble the energy storage devices into modules, and the module capacity (modules using 8 series, 2 parallel 8 series, 5 parallel 8 series and 10 parallel 8 series), the final charge / discharge voltage monomer voltage difference (modules all use 5 parallel 8 series), and the cycle discharge effect (modules use 5 parallel 8 series) were compared; the comparison diagrams are as shown in the attached figure. Figures 5 to 7 shown.

[0023] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for combining soft-pack energy storage devices in series and parallel, characterized in that: When connected in series, ensure that the voltage range of each soft-pack energy storage device in the series branch is 0 to 10mV; when connected in parallel, ensure that the capacity range of the parallel branch is 0 to 15mAh.

2. A method for combining soft-pack energy storage devices in series and parallel according to claim 1, characterized in that: When connected in series, ultrasonic welding is used to connect the positive and negative pole ears of the soft-pack energy storage device together to form a series branch.

3. A method for combining soft-pack energy storage devices in series and parallel according to claim 2, characterized in that: During series welding, use a straight slot fixture to fix the soft-package energy storage device.

4. A method for combining soft-pack energy storage devices in series and parallel according to claim 3, characterized in that: When connected in parallel, laser welding of nickel strips is used to achieve parallel connection between multiple series branches.

5. A method for combining soft-pack energy storage devices in series and parallel according to claim 4, characterized in that: When there are a large number of soft-pack energy storage devices in series and in parallel, the form of folding and then stacking is adopted, that is, first laying them flat in series and in parallel, and then folding and laying them flat on the surface of the lower soft-pack energy storage device.

6. A method for combining soft-pack energy storage devices in series and parallel according to any one of claims 1 to 5, characterized in that: The soft-pack energy storage device is a lithium-ion battery.

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