JP7142697B2 - How to repair used battery modules - Google Patents

Description

The present application relates to the field of repairing battery module performance, and in particular to methods for repairing used battery modules.

In recent years, with the rapid development of electric vehicles, the battery industry is also actively expanding. Lithium-ion battery technology is currently one of the important technologies in electric vehicle systems. In the process of using lithium-ion batteries, battery service life and cost are two key factors that constrain the development of electric vehicles. In 2016, China's electric vehicle sales reached 517,000 units, and in 2017, the market sales reached about 700,000 units. Based on the battery life of 5 years, by 2020, the China Automotive Technology Research Center predicts that the used amount of automotive batteries in China will reach 322,000 tons. With the popularization of new energy vehicles and the passage of time, the pressure to collect used batteries is increasing more and more.

The used battery module can be reused after the battery performance is restored by the lithium ion battery restoration method and the restoration is completed. However, the conventional method of repairing used battery modules is performed on lithium-ion battery single cells, that is, after dismantling the used battery module into lithium-ion battery single cells, the After repairing the used battery module and completing the repair of the used battery module, the single cell of the lithium ion battery is assembled into the used battery module.

In other words, the conventional method for repairing used battery modules is labor intensive, and the cost of repairing used battery modules is high.

An object of the present application is to provide a method for repairing a used battery module with low cost when repairing the used battery module.

1. A method for refurbishing a used battery module comprising a plurality of single-string batteries consisting of 3 to 20 individual cells paralleled together in series, the method comprising the steps of:
charging the used battery module to an upper limit voltage;
canceling the parallel state of the plurality of single-line batteries in the used battery module;
After leaving the used battery module charged to the upper limit voltage stationary for a predetermined time, each of the single-line batteries is charged to the upper limit voltage;
discharging each of the single-string batteries to a lower voltage limit;
A method of repairing a used battery module, comprising: paralleling a plurality of the single-row batteries.

The used battery module repair method does not need to dismantle the used battery module into single cells when repairing the used battery module, and can maintain the overall appearance of the used battery module; In addition, each single-row battery can be repaired by releasing only the parallel state of the plurality of single-row batteries. Compared with the conventional used battery module repair method, the used battery module repair method has a lower cost in repairing the used battery module.

The following briefly describes the drawings required in the embodiments or the prior art in order to describe the technical solutions in the embodiments or the prior art of the present application more clearly. It is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained based on these drawings for those skilled in the art without creative effort. .

4 is a flow chart of a used battery module repair method in one embodiment.

The following clearly and completely describes the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Apparently, the described embodiments are merely some rather than all embodiments of the present application. According to the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor should belong to the protection scope of the present application.

As shown in FIG. 1, a used battery module refurbishment method in one embodiment is used to perform performance refurbishment on a used battery module. It includes the following steps.

S100: Charge the used battery module to the upper limit voltage.

A used battery module includes a plurality of single-string batteries that are paralleled together. Each single-row battery is formed by a number of battery units connected in series.

Specifically, a used battery module includes 3 to 20 single-string batteries that are paralleled together. Each single-row battery is formed by connecting 3 to 20 individual batteries in series.

The upper limit voltage differs depending on the used battery module. Generally, the upper limit voltage of a battery unit is 3.6V to 4.2V, and the upper limit voltage of a used battery module is determined according to the number of battery units actually connected in series.

In this embodiment, before step S100, the used battery module is discharged to the lower limit voltage at a temperature of 23° C. to 27° C.; Completing the discharge is convenient for performing subsequent repair steps.

S200: Release the parallel state of the single-row batteries in the used battery module.

Specifically, S200 opens the housing of the used battery module to expose the positive/negative posts of the plurality of single-row batteries, and then releases the parallel state of the plurality of single-row batteries in the used battery module. It is to be.

S300: After the used battery module charged to the upper limit voltage is allowed to stand still for a predetermined time, each single-row battery is charged to the upper limit voltage.

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

In this embodiment, the upper limit voltage of the single-row battery matches the upper limit voltage of the used battery module. This is because multiple single-row batteries are arranged in parallel to form a used battery module.

Preferably, the predetermined time is 1 hour to 24 hours.

More preferably, the predetermined time is 1 hour to 2 hours.

In this embodiment, the breaking current of the single battery is 0.02C.

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

In a preferred embodiment, S300 further includes, after the operation of charging each single-row battery to the upper limit voltage, allowing the plurality of single-row batteries to stand still for a predetermined time, and then charging each single-row battery to the upper limit voltage again. include.

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

In this embodiment, the charging and standing steps are both performed at a constant temperature of 30.degree. C. to 60.degree. By repairing the performance of the single-row battery, the SEI film on the negative electrode surface of the single battery in the single-row battery is repaired more precisely, and the uniformity of the single battery after repair is good.

Preferably, the performance of the single-row battery is restored at a high temperature of 45° C. to 60° C., so that the negative electrode surface SEI film of the single battery in the single-row battery is more uniformly and stably restored, The uniformity of the battery unit after being repaired is also better.

In this embodiment, the predetermined standing time is 1 hour to 24 hours. A single-row battery discharges slowly to some extent when it is left at rest, and then performs a charging operation after it is left at rest. After being charged to the upper limit voltage, the upper limit of the battery capacity of the single battery can be repaired and improved.

Preferably, the predetermined standing time is 1 hour to 2 hours. A shorter resting time satisfies the resting need, ie the charging operation can be performed again.

In addition, after the single battery is fully charged, it is charged again, which causes the single battery to be quickly charged to the upper limit voltage. Therefore, the charging time for double charging is short, which may be ten seconds or even one minute. Different cell sizes can cause changes in charging time. The purpose is to restore the upper limit of the battery capacity of the single battery by carrying out the overlapping charging process of rest-charge-rest-charge after the single battery is fully charged.

S400: Discharge each single-row battery to the lower limit voltage.

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

S500: A plurality of single-row batteries are arranged in parallel.

Specifically, S500 is attaching a housing of a used battery module after paralleling a plurality of single-row batteries.

A lithium-ion battery module becomes a used battery module when the capacity of the battery module decays to 70% or less of its initial capacity after repeated use. By performing performance restoration of the used battery module using the used battery module restoration method, the battery capacity of the used battery module is reduced by 20% or more compared to the capacity of the battery module before restoration. It can be repaired and improved, and the battery capacity of used battery modules can be greatly improved.

The used battery module repair method does not need to dismantle the used battery module into single cells when repairing the used battery module, and can maintain the overall appearance of the used battery module; Moreover, each single-row battery can be repaired by releasing only the parallel state of the plurality of single-row batteries. Compared with the conventional used battery module repair method, the used battery module repair method has a lower cost in repairing the used battery module.

The following are specific examples.

Examples 1 to 6

Hereinafter, using the used used battery module in Table 1 as a sample, the sample number is B, and a repair test was performed using the process method of the present application. The charging/discharging test equipment is ECT05100A energy feedback type battery detection equipment D manufactured by Shenzhen Hengyuneng Science and Technology Co., Ltd.

The repair method and operation steps are as follows.

P1: Using the detector D, the used battery module after completion of charging was discharged to the lower limit voltage at a constant current of 0.5 C, and the discharge capacity C0 was recorded. The lower limit voltage of a single lithium iron phosphate battery is 2.0V.

P2: Charge the used battery module to the upper limit voltage, open the housing of the used battery module to expose the positive/negative posts of multiple single-row batteries, and then multiple single-row batteries in the used battery module. (i.e. unwound the leads that are wound on the post to achieve parallelism).

P3: After leaving the used battery module charged to the upper limit voltage for 1 hour, each single-row battery was charged to the upper limit voltage. The upper limit voltage of a single lithium iron phosphate battery is 3.6V, and the breaking current under constant voltage charging is 0.02C. After the single-row batteries after charging were left to stand still for 1 hour, each single-row battery was again charged to the upper limit voltage at constant current and constant voltage. The charging current is 0.1-0.5C, the upper limit voltage of a single lithium iron phosphate battery is 3.6V, and the breaking current is 0.02C under constant voltage charging.

P4: Each single-row battery was discharged from the upper limit voltage to the lower limit voltage at a constant current. The discharge current is 0.1-0.5C, and the lower limit voltage of a single lithium iron phosphate battery is 2.0V.

P5: After repeating P3 and P4 three times and arranging a plurality of single-line batteries in parallel, the used battery module housing was attached.

P6: In a normal temperature environment, the used battery module after completion of restoration was charged to the upper limit voltage at a constant current and constant voltage of 0.5C. Breaking current is 0.02C. Then, it was discharged to the lower limit voltage at a constant current of 0.5C. The discharge capacity C1 was recorded.

Examples 1-6 and Comparative Examples 1-3: Sample B was repaired according to the steps above. Repairs were performed according to the different process conditions in Table 2 and the capacity results before and after repair under each condition are shown in Table 2.

As can be seen from the above table, when charging/discharging the used battery module at different currents, the effect of charging/discharging at a current of 0.1C at 45° C. is the best. However, due to the excessively long charging/discharging time at a current of 0.1C, the production efficiency was lowered. Moreover, the charge/discharge restoration capacity at a current of 0.1C is not clearly improved over the restoration capacity at a current of 0.2C. Combining production efficiency, energy consumption and repair effect, the optimum conditions of the process according to the present application are set at 45° C. and charging and discharging with a current of 0.2C.

It can be seen from the test results that the present application can dismantle the used battery module into battery unit cells while subjecting the used battery module to several small-current charge-discharge cycling repairs in a high-temperature environment. Instead, the SOC discharge end of the single string cell was aligned in the low current discharge mode. Therefore, it is possible to improve the dischargeable capacity of the used battery module after repair. The overlapping cycle of resting and recharging can improve the battery discharge capacity after repair by more than 20% over that before repair. By installing the repaired battery in an automobile in response to a similar request and using it repeatedly, it can be used continuously for three years or more, and the useful life of the battery can be improved.

The refurbishment method of the present application is simple in process, easy to operate, and low in cost, and by refurbishing used lithium-ion batteries, it saves money and energy, reduces the waste rate of batteries, and saves the environment. can be protected and has important practical application value.

The present application is not limited to performing performance repairs on spent power lithium-ion batteries. After using various types of lithium ion batteries with various positive/negative materials and various housings in various fields, if the circulating capacity drops to about 70%, the technical solution can be used to improve the battery performance. can be repaired and improved.

The above-described examples merely describe some embodiments of the invention. The description, while specific and detailed, should not be construed as limiting the scope of the claims. For those skilled in the art, some variations and improvements made without departing from the concept of the present invention should fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the attached claims.

(Appendix)
(Appendix 1)
1. A method for refurbishing a used battery module comprising a single string battery comprising a plurality of single cells serially connected together in parallel, the method comprising the steps of:
charging the used battery module to an upper limit voltage;
canceling the parallel state of the plurality of single-line batteries in the used battery module;
After leaving the used battery module charged to the upper limit voltage for a predetermined time, charging each of the single-line batteries to the upper limit voltage;
discharging each of the single-string batteries to a lower voltage limit;
and paralleling a plurality of the single-line batteries.
A method for repairing a used battery module, characterized by:

(Appendix 2)
After the operation of charging each of the single-line batteries to the upper limit voltage, after allowing the plurality of single-line batteries to stand still for the predetermined time, charging each of the single-line batteries to the upper limit voltage again.
A method for repairing a used battery module according to Supplementary Note 1, characterized by:

(Appendix 3)
After leaving the plurality of single-line batteries stationary for the predetermined time, the operation of charging each of the single-line batteries again to the upper limit voltage is duplicated, and the number of times of duplication is 2 to 10 times.
A method for repairing a used battery module according to appendix 2, characterized by:

(Appendix 4)
Disconnecting the plurality of single-row batteries in the used battery module from the parallel state includes: opening the housing of the used battery module to expose the positive/negative posts of the plurality of single-row batteries; canceling the parallel state of the plurality of single-row batteries in the used battery module;
A method for repairing a used battery module according to Supplementary Note 1, characterized by:

(Appendix 5)
Paralleling a plurality of the single-line batteries includes attaching a housing of the used battery module after paralleling the plurality of the single-line batteries.
A method for repairing a used battery module according to Supplementary Note 1, characterized by:

(Appendix 6)
wherein the used battery module comprises 3 to 20 of the single-row batteries paralleled together, each of the single-row batteries being formed by 3 to 20 of the battery units in series;
A method for repairing a used battery module according to any one of Appendices 1 to 5, characterized by:

(Appendix 7)
The predetermined time is 1h to 24h,
A method for repairing a used battery module according to any one of Appendices 1 to 5, characterized by:

(Appendix 8)
The predetermined time is 1h to 2h,
A method for repairing a used battery module according to appendix 7, characterized by:

(Appendix 9)
The breaking current of the single-string battery is 0.02C,
A method for repairing a used battery module according to any one of Appendices 1 to 5, characterized by:

(Appendix 10)
The charging current of the single-row battery is 0.1C to 0.5C, and the discharging current of the single-row battery is 0.1C to 0.5C.
A method for repairing a used battery module according to any one of Appendices 1 to 5, characterized by:

Claims (8)

1. A method for refurbishing a used battery module comprising a plurality of single-string batteries consisting of 3 to 20 individual cells paralleled together in series, the method comprising the steps of:
charging the used battery module to an upper limit voltage;
canceling the parallel state of the plurality of single-line batteries in the used battery module;
After leaving the used battery module charged to the upper limit voltage stationary for a predetermined time, each of the single-line batteries is charged to the upper limit voltage;
discharging each of the single-string batteries to a lower voltage limit;
and paralleling a plurality of the single-line batteries.
A method for repairing a used battery module, characterized by: After the operation of charging each of the single-line batteries to the upper limit voltage, after allowing the plurality of single-line batteries to stand still for the predetermined time, charging each of the single-line batteries to the upper limit voltage again.
The used battery module repair method according to claim 1, characterized in that: After leaving the plurality of single-line batteries stationary for the predetermined time, the operation of charging each of the single-line batteries again to the upper limit voltage is duplicated, and the number of times of duplication is 2 to 10 times.
The used battery module repair method according to claim 2, characterized in that: Disconnecting the plurality of single-row batteries in the used battery module from the parallel state includes: opening the housing of the used battery module to expose the positive/negative posts of the plurality of single-row batteries; canceling the parallel state of the plurality of single-row batteries in the used battery module;
The used battery module repair method according to claim 1, characterized in that: Paralleling a plurality of the single-line batteries includes attaching a housing of the used battery module after paralleling the plurality of the single-line batteries.
The used battery module repair method according to claim 1, characterized in that: The predetermined time is 1h to 24h,
The used battery module repair method according to any one of claims 1 to 5, characterized in that: The predetermined time is 1h to 2h,
The used battery module repair method according to claim 6 , characterized in that: The charging current of the single-row battery is 0.1C to 0.5C, and the discharging current of the single-row battery is 0.1C to 0.5C.
The used battery module repair method according to any one of claims 1 to 5, characterized in that:

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