WO2021163985A1

WO2021163985A1 - Method for repairing decommissioned battery module

Info

Publication number: WO2021163985A1
Application number: PCT/CN2020/076109
Authority: WO
Inventors: 刘晨露; 邓波; 罗勇; 孟超; 刘卫强
Original assignee: 深圳市普兰德储能技术有限公司
Priority date: 2020-02-21
Filing date: 2020-02-21
Publication date: 2021-08-26
Also published as: JP2022524170A; JP7142697B2; AU2020202737B1; SG11202003648UA

Abstract

A method for repairing a decommissioned battery module, comprising the following steps: charging a decommissioned battery module to an upper limit voltage (S100); releasing a state of parallel connection between a plurality of single columns of cells in the decommissioned battery module (S200); leaving the decommissioned battery module charged to the upper limit voltage to stand for a preset time, and separately charging each single column of cells to the upper limit voltage (S300); discharging all the single columns of cells to a lower limit voltage (S400); and connecting the plurality of single columns of cells in parallel (S500). When repairing a decommissioned battery module, the described method for repairing a decommissioned battery module does not need to disassemble the decommissioned battery module into single cells, but maintains the entire form of the decommissioned battery module, releases parallel connection between a plurality of single columns of cells, and repairs each single column of cells. Compared with the conventional methods, the described method for repairing a decommissioned battery module has a low cost in repairing a decommissioned battery module.

Description

Repair method of retired battery module

Technical field

This application relates to the field of battery module performance restoration, and in particular to a method for repairing decommissioned battery modules.

Background technique

In recent years, with the rapid development of the electric vehicle industry, the battery industry is also actively expanding. Lithium-ion battery technology has now become one of the key technologies in electric vehicle systems. During the use of lithium-ion batteries, the battery life and cost are Two key factors restricting the development of electric vehicles. China’s electric vehicle sales reached 517,000 in 2016, and the market sales in 2017 is expected to be approximately 700,000. Based on the 5-year service life of the battery, according to the China Automotive Technology Research Center, the cumulative decommissioning of China’s automotive batteries will reach With the scale of 322,000 tons, with the promotion of new energy vehicles and the passage of time, the pressure on battery decommissioning and recycling will also increase.

Retired battery modules can be repaired by lithium-ion battery repair methods, and can be used again after the repair is completed. However, the traditional repair method for retired battery modules is carried out on the single cells of lithium-ion batteries, that is, after the retired battery modules are disassembled into single cells of lithium-ion batteries, they are repaired for the single cells of lithium-ion batteries. After the repair of the decommissioned battery module is completed, the lithium-ion battery cells are reassembled into a decommissioned battery module.

In other words, the traditional repair method of the decommissioned battery module is time-consuming and laborious, and the cost of repairing the decommissioned battery module is relatively high.

Application content

The purpose of the present application is to provide a method for repairing a decommissioned battery module, which has a lower cost when repairing the decommissioned battery module.

A method for repairing a decommissioned battery module, the decommissioned battery module includes a plurality of single-string batteries connected in parallel, and each single-string battery is formed by a number of battery cells connected in series, including the following steps:

Charging the decommissioned battery module to an upper limit voltage;

Releasing the parallel state of the plurality of single-string batteries in the decommissioned battery module;

Charging the decommissioned battery module to the upper limit voltage to stand for a preset time, and then separately charging each single string battery to the upper limit voltage;

Discharging each of the single-string batteries to a lower limit voltage; and

A plurality of the single-string batteries are connected in parallel.

The above method for repairing the decommissioned battery module does not need to disassemble the decommissioned battery module into a single cell when repairing the decommissioned battery module, but maintains the overall shape of the decommissioned battery module. The parallel connection between the batteries is released, and repairs are carried out for each single string battery. Compared with the traditional repair method of the decommissioned battery module, the above-mentioned repair method of the decommissioned battery module has a lower cost when repairing the decommissioned battery module.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

in:

FIG. 1 is a flowchart of a method for repairing a decommissioned battery module according to an embodiment.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this application.

As shown in FIG. 1, a method for repairing a decommissioned battery module in an embodiment is used to perform performance repair on a decommissioned battery module, which includes the following steps:

S100. Charge the decommissioned battery module to the upper limit voltage.

The decommissioned battery module includes a plurality of single-string batteries connected in parallel, and each single-string battery is formed by a number of battery cells connected in series.

Specifically, the decommissioned battery module includes 3-20 single-string batteries connected in parallel. Each single string battery can be formed by connecting 3 to 20 battery cells in series.

The upper limit voltage differs depending on the retired battery module. Generally speaking, the upper limit voltage of a battery cell is 3.6V-4.2V, and the upper limit voltage of a decommissioned battery module is determined according to the number of battery cells actually connected in series.

In this embodiment, before step S100, it also includes discharging the decommissioned battery module to the lower limit voltage at a temperature of 23°C to 27°C. Under normal temperature, the work discharge process of the decommissioned battery module is completed to complete the decommissioning battery module. Discharge of the group to facilitate the subsequent repair process.

S200. Release the parallel state of the multiple single-string batteries in the decommissioned battery module.

Specifically, S200 is: opening the casing of the decommissioned battery module to expose the positive and negative terminals of the multiple single-string batteries, and then cancel the parallel state of the multiple single-string batteries in the retired battery module.

S300. The decommissioned battery modules are charged to the upper limit voltage and stand for a preset time, and then each single string battery is charged to the upper limit voltage respectively.

Generally speaking, the upper limit voltage of a battery cell is 3.6V～4.2V, and the upper limit voltage of a single string battery is determined according to the number of battery cells actually connected in series.

In this embodiment, the upper limit voltage of the single string battery is the same as the upper limit voltage of the decommissioned battery module. This is because a plurality of single string batteries are connected in parallel to form a decommissioned battery module.

Preferably, the preset time is 1h-24h.

More preferably, the preset time is 1h-2h.

In this embodiment, the cut-off current of the single string battery is 0.02C.

In this embodiment, the charging current of the single string battery is 0.1C-0.5C.

In a preferred embodiment, S300 further includes the following operations after the operation of separately charging each single-string battery to the upper limit voltage: rest the multiple single-string batteries for a preset time, and then separately perform the following operations on each single battery. The string battery is charged to the upper limit voltage.

More preferably, the operation of allowing a plurality of single-string batteries to stand for a preset time, and then separately charging each single-string battery to the upper limit voltage is a repeated cycle operation, and the number of repetitions is 2 to 10 times.

In this embodiment, the above steps of charging and standing are performed at a constant temperature of 30°C-60°C to repair the performance of the single string battery, so that the SEI film on the negative electrode surface of the battery cell in the single string battery can be repaired. It is denser, and the consistency of the repaired battery cell is good.

Preferably, the performance of the single-string battery is repaired at a high temperature of 45℃-60℃, so that the SEI film on the negative electrode surface of the battery cell in the single-string battery is repaired more uniformly and more stably, and the repaired battery cell The consistency is also better.

In this embodiment, the preset time of standing is 1h-24h. When standing, the single string battery will be slowly discharged to a certain extent. After standing still, the charging operation can be carried out. When the charging reaches the upper limit voltage, it can be repaired and increased. The upper limit of the battery capacity of a single string battery.

Preferably, the preset time of standing is 1h-2h, and the shorter standing time can meet the standing requirements, and then the recharging operation can be performed.

It should be noted that because the single-string battery is fully charged and then recharged, the single-string battery will be fully charged to the upper limit voltage faster. Therefore, the charging time for repeated charging is shorter, which may be ten seconds or 1 Minutes, different battery cell models will also lead to changes in the charging time. The purpose is to realize the repeated charging process of standing-charging-still-charging for single-string batteries after being fully charged, so as to repair the upper limit of the battery capacity of single-string batteries. .

S400. Discharge each single string battery to a lower limit voltage.

In this embodiment, the discharge current of the single string battery is 0.1C-0.5C.

S500. Connect multiple single-string batteries in parallel.

Specifically, S500 is: connect multiple single-string batteries in parallel, and then install the shell of the decommissioned battery module.

When the lithium-ion battery module is recycled and the capacity of the battery module decays to less than 70% of the initial capacity, it will be decommissioned and become a decommissioned battery module. The above-mentioned repair method of the decommissioned battery module is used to carry out the performance of the decommissioned battery module. Repair, compared with the capacity of the battery module before the repair, the battery capacity of the decommissioned battery module can be repaired by more than 20%, which greatly improves the battery capacity of the decommissioned battery module.

The following is a specific example

Example 1-Example 6

The decommissioned battery modules in the following Table 1 are taken as samples, and the sample numbers are respectively: B, which are repaired and tested using the process method of this application. The charge and discharge test equipment is the ECT05100A energy feedback battery testing equipment D produced by Shenzhen Hengyi Energy Technology Co., Ltd.

Table 1: Samples of retired battery modules

样品编号Sample serial number	包装壳及形态Packaging shell and shape	额定容量C(Ah)Rated capacity C(Ah)	正极活性材料Positive electrode active material
BB	方形铝壳Square aluminum shell	140140	LiFePO ₄ LiFePO ₄

The repair method and operation steps are as follows:

P1: Discharge the fully-charged decommissioned battery module testing device D at a constant current of 0.5C to the lower limit voltage, record the discharge capacity C0, and the lower limit voltage of a single lithium iron phosphate battery is 2.0V.

P2: Charge the decommissioned battery module to the upper voltage limit, open the shell of the decommissioned battery module to expose the positive and negative terminals of multiple single strings, and then release the parallel state of multiple single strings in the retired battery module (It is about to untie the wires that are wound on the terminal to realize the parallel connection).

P3: Charge the decommissioned battery module to the upper limit voltage and let it stand for 1 hour, and then charge each single battery to the upper limit voltage. The upper limit voltage of a single lithium iron phosphate battery is 3.6V, and the constant voltage charging cut-off current is 0.02C. Let the fully charged single-string battery stand for 1h, and then charge each single-string battery to the upper limit voltage with constant current and voltage. The charging current is 0.1-0.5C. The upper limit voltage of a single lithium iron phosphate battery is 3.6V, constant voltage. The charge cut-off current is 0.02C.

P4: Discharge each single string battery from the upper limit voltage and constant current to the lower limit voltage; the discharge current is 0.1-0.5C, and the lower limit voltage of a single lithium iron phosphate battery is 2.0V.

P5: Repeat P3 and P4 three times to connect multiple single-string batteries in parallel, and then install the shell of the decommissioned battery module.

P6: In a normal temperature environment, the retired battery module after repair is charged to the upper limit voltage at a constant current and voltage of 0.5C, the cut-off current is 0.02C, and then discharged to the lower limit voltage at a constant current of 0.5C. Record the discharge capacity C1.

Examples 1-6 and Comparative Examples 1-3: Sample B was repaired according to the above steps, and repaired according to the different process condition settings in Table 1 below, and the capacity results before and after repair under various conditions are shown in Table 1.

Table 2: Sample B's capacity improvement before and after repair with 0.1C-0.5C charge and discharge current at 25-60℃

It can be seen from the above table that when the retired battery modules are charged and discharged with different currents, the charging and discharging repair capacity with 0.1C current at 45°C has the best relative effect, but the 0.1C current charging and discharging time is too long, resulting in low production efficiency. And 0.1C current charge and discharge repair capacity is not significantly improved compared to 0.2C repair capacity. Considering the production efficiency, energy consumption, and capacity repair effect, the optimal conditions for the process implemented in this application are set as: 0.2C current charge and discharge at 45°C.

The experimental results show that this application only needs to repair the decommissioned battery module in a higher temperature environment for several low-current charge and discharge cycles, and at the same time, without disassembling the decommissioned battery module into battery cells, Align the SOC discharge end of the single string battery with a small current discharge method, increase the discharge capacity of the decommissioned battery module after repair, and repeat the cycle of standing and recharging. After the repair, the battery discharge capacity is increased by more than 20% than before the repair. The repaired battery is loaded and recycled according to the same requirements, and it can continue to be used for more than 3 years, which extends the battery life.

The repair method of the application has simple process, convenient operation and low cost. By repairing decommissioned lithium-ion batteries, it can save money and energy, reduce battery scrap, and protect the environment, which has important practical application value.

This application is not limited to the performance repair of retired power lithium-ion batteries, as long as the cycle capacity of various types of lithium-ion batteries in various fields, various positive and negative materials, various packaging shells, etc. decreases to about 70% after use. This technical solution can be used to effectively repair and improve battery performance.

The above-mentioned embodiments only express several embodiments of the present invention, and the descriptions are more specific and detailed, but they should not be understood as a limitation on the scope of patent application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A method for repairing a retired battery module, the retired battery module includes a plurality of single-string batteries connected in parallel, and each single-string battery is formed by a plurality of battery cells connected in series, and is characterized in that it comprises the following steps :

Charging the decommissioned battery module to an upper limit voltage;

Releasing the parallel state of the plurality of single-string batteries in the decommissioned battery module;

Charging the decommissioned battery module to the upper limit voltage to stand for a preset time, and then separately charging each single string battery to the upper limit voltage;

Discharging each of the single-string batteries to a lower limit voltage; and

A plurality of the single-string batteries are connected in parallel.
The method for repairing a decommissioned battery module according to claim 1, further comprising, after the operation of separately charging each of the single-string batteries to the upper limit voltage, performing the following operations: The single-string batteries are allowed to stand for the preset time, and each single-string battery is separately charged to the upper limit voltage again.
The method for repairing a decommissioned battery module according to claim 2, wherein the plurality of single-string batteries are allowed to stand for the preset time, and each single-string battery is charged to all the batteries again. The operation of the upper limit voltage is a repeated cycle operation, and the number of repetitions is 2 to 10 times.
The method for repairing a decommissioned battery module according to claim 1, wherein the operation of releasing the parallel state of the plurality of single-string batteries in the decommissioned battery module is: The shell of the group is opened to expose the positive and negative terminals of the plurality of single-string batteries, and then the parallel state of the plurality of single-string batteries in the decommissioned battery module is released.
The method for repairing a decommissioned battery module according to claim 1, wherein the operation of connecting a plurality of the single-string batteries in parallel is: connecting a plurality of the single-string batteries in parallel, and then connecting the decommissioned batteries The housing of the module is installed.
The method for repairing a decommissioned battery module according to any one of claims 1 to 5, wherein the decommissioned battery module comprises 3 to 20 single-string batteries connected in parallel, each The single string battery is formed by connecting 3 to 20 battery cells in series.
The method for repairing a decommissioned battery module according to any one of claims 1 to 5, wherein the preset time is 1 hour to 24 hours.
The method for repairing a decommissioned battery module according to claim 7, wherein the preset time is 1h-2h.
The method for repairing a decommissioned battery module according to any one of claims 1 to 5, wherein the cut-off current of the single string battery is 0.02C.
The method for repairing a decommissioned battery module according to any one of claims 1 to 5, wherein the charging current of the single-string battery is 0.1C-0.5C, and the discharging current of the single-string battery is 0.1C-0.5C. C-0.5C.