CN112114266A - One-step method for battery sieving grouping - Google Patents

Abstract

The invention provides a method for realizing battery screening and grouping in one step. Then put it to a certain voltage V ₁ , record the charging capacity C ₀ and V ₁ ; 3) Let the battery stand, record the voltage V ₂ and time T ₁ after depolarization; 4) Let the battery stand, record the voltage V after the battery voltage drop ₃ and time T ₂ ; 5) Classify by battery capacity, degree of depolarization, and self-discharge voltage drop. The invention realizes a method for realizing battery screening and grouping in one step, which can greatly shorten the product production cycle, reduce production costs, and can accurately pick out abnormal batteries, realize battery grouping, and optimize the existing battery screening and grouping process. And the new system battery process is determined, providing a new idea.

Description

One-step method for battery sieving grouping

technical field

The invention relates to the technical field of lithium ion batteries, in particular to a method for realizing battery sieving and grouping in one step.

Background technique

With the improvement of people's living standards, people's requirements for the living environment are also increasing day by day. The traditional pollution sources, nickel-metal hydride, nickel-chromium and lead-acid batteries are gradually being banned, and replaced by more energy-saving and environmentally friendly new energy lithium batteries. The increase in demand for lithium-ion batteries has prompted the continuous addition and expansion of battery factories, and also accelerated industry competition. Screening and grouping is to remove abnormal batteries and use batteries with similar performance. It is an important link in the production of lithium batteries and is related to the safety and consistency of battery use. Different enterprises, the technology is very different, and the production cycle is long and the cost is high. Therefore, as one of the core technologies of lithium battery enterprises, screening grouping requires more investment in technology development.

The traditional screening and grouping process often includes multiple processes, such as pre-charging, storage, OCV testing, capacity distribution, etc. Finally, according to the data of capacity, static internal resistance, discharge platform time, charge and discharge efficiency or open circuit voltage, two or three The item classifies the battery to realize the matching group. This process has a long production cycle and is troublesome to operate, which undoubtedly greatly increases the product cost.

SUMMARY OF THE INVENTION

The invention proposes a method for realizing battery screening and grouping in one step. The battery capacity is calculated by charging capacity and first effect, the depolarization degree K ₁ of the battery is calculated by the voltage rebound at the end of discharge, and the self-discharge voltage of the battery is calculated by the voltage drop before and after shelving. Drop the K2 value, and screen the batteries according to the battery capacity, the depolarization degree _K1 , and the self _- discharge voltage drop _K2 value.

The technical scheme that realizes the present invention is:

A method for realizing battery screening grouping in one step, comprising the following steps:

1) Determine the first efficiency of the battery of a certain system, select a fresh battery after the aging of a certain system, charge the battery to full charge for the first time, discharge it to the cut-off voltage, cycle for one week, record the battery charge and discharge capacity C, C`, calculate the battery of the system The first-effect fixed value I=C`/C*100%, before the system and process are not changed, this value is used for the subsequent calculation of battery capacity;

2) The battery is pre-charged to a certain voltage V ₁ after being fully charged. The discharge current is 0.1C-10C, preferably 1C-5C, and the voltage should be above the platform voltage, preferably in the range of 3.8-4.0V, and record the charging capacity C ₀ and V ₁ , calculate the battery capacity C ₁ =C ₀ *I;

3) Put the battery in a 25℃-55℃ environment for 0.1h~4h, preferably 0h~2h, record the voltage V ₂ and time T ₁ after depolarization, and calculate the voltage change with time K ₁ =(V ₂ -V ₁ );

4) Continue to place the battery in the environment of 25℃-55℃ for 4~24h, preferably 12~24h, record the voltage V ₃ and time T ₂ after the voltage drop of the battery, and calculate the voltage change with time K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ );

5) Classified by battery capacity, degree of depolarization, and self-discharge voltage drop;

The battery is divided into grades using battery discharge capacity C', depolarization degree K ₁ =(V ₂ -V ₁ ), and self-discharge voltage drop K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ ).

The beneficial effects of the present invention are:

The invention calculates the battery capacity through the charging capacity and the first effect during the pre-charging process, calculates the battery depolarization degree K ₁ through the voltage rebound at the end of discharge, calculates the battery self-discharge voltage drop K ₂ through the voltage drop before and after shelving, and finally The batteries were screened and grouped according to the battery capacity, the degree of depolarization K1 and the value _of the self _- discharge voltage drop K2. The invention is scientific and reasonable, simple to operate, suitable for batteries of different systems, and provides a new way of thinking for the optimization of the existing battery screening and grouping process and the determination of the battery process of the new system.

The invention realizes a method for realizing battery screening and grouping in one step, which can greatly shorten the product production cycle, reduce production cost, and can accurately pick out abnormal batteries, realize battery grouping, and optimize the existing battery screening and grouping process. And the new system battery process is determined, providing a new idea.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the accompanying drawings without creative efforts.

Figure 1 is a schematic diagram of the process selection.

Detailed ways

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

In the examples, the negative electrode of the battery adopts high-rate graphite, and the positive electrode adopts small-particle lithium cobalt oxide to prepare a 16Ah high-rate drone battery. Select a certain amount of fresh batteries after aging in this system, charge and discharge the battery for one week for the first time, record the battery charge and discharge capacities C and C`, and calculate the first-efficiency value of the battery in this system I=C`/C*100%=(C1` /C1+C2`/C2+C10`/C10)/10*100%=87.03%.

Example 1

After the battery is pre-charged to full charge, put it at 0.1C to 3.8V, record the charging capacity C ₀ =18.880Ah, calculate the battery capacity C ₁ =C ₀ *I=18.880*87.03%=16.431Ah, and place the battery in a 25°C environment After standing for 0.1h, record the voltage V ₂ =3.940V and time T ₁ =0.1h after depolarization, calculate the voltage change with time K ₁ =(V ₂ -V ₁ )=3.940-3.8=0.14V, continue on 25 After standing in the environment of ℃ for 24h, record the voltage V ₃ = 3.937V and time T ₂ =24.1h after recording the voltage drop, calculate the voltage change with time K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ ) =0.125mV/h. Finally, the batteries are screened and grouped according to the values of C ₁ , K ₁ and K ₂ , and the abnormal products whose K ₁ and K ₂ differ by more than 5% are excluded. Screening grouping of batteries.

Example 2

After the battery is pre-charged to full charge, put it to 3.8V at 5C, record the charge and charge capacity C ₀ , calculate the battery capacity C ₁ =C ₀ *I, place the battery in a 55°C environment for 0.1h, and record the voltage V after depolarization ₂ and time T ₁ , calculate the voltage change with time K ₁ =(V ₂ -V ₁ ), continue to stand at 55℃ for 24h, record the voltage V ₃ and time T ₂ after the voltage drop, calculate the voltage with time Change K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ ). Finally, the batteries are screened and grouped according to the values of C ₁ , K ₁ and K ₂ , and the abnormal products whose K ₁ and K ₂ differ by more than 5% are excluded. , divide the remaining battery capacity into a grade for every difference of 50mAh, and realize the screening and grouping of the battery.

Example 3

After the battery is precharged to full charge, put it at 0.1C to 4.1V, record the charge and charge capacity C ₀ , calculate the battery capacity C ₁ =C ₀ *I, place the battery in a 25°C environment for 0.1h, and record the voltage after depolarization V ₂ and time T ₁ , calculate the voltage change with time K ₁ =(V ₂ -V ₁ ), continue to stand at 25℃ for 12h, record the voltage V ₃ and time T ₂ after the voltage drop, calculate the voltage change with time Time change K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ ), and finally the batteries are screened and grouped according to the values of C ₁ , K ₁ and K ₂ , and the abnormal difference between K ₁ and K ₂ by more than 5% is excluded For each product, the remaining battery capacity is divided into a grade for every 50mAh difference to realize the screening and grouping of the battery.

Example 4

After the battery is pre-charged to full charge, put it at 0.1C to 3.9V, record the charging and charging capacity C ₀ , calculate the battery capacity C ₁ =C ₀ *I, place the battery in a 25°C environment for 4 hours, and record the voltage V after depolarization ₂ and time T ₁ , calculate the voltage change with time K ₁ =(V ₂ -V ₁ ), continue to stand at 55℃ for 4h, record the voltage V ₃ and time T ₂ after the voltage drop, calculate the voltage with time Change K ₂ =(V ₃ -V ₂ )/(T ₂ -T ₁ ). Finally, the batteries are screened and grouped according to the values of C ₁ , K ₁ and K ₂ , and the abnormal products whose K ₁ and K ₂ differ by more than 5% are excluded. , divide the remaining battery capacity into a grade for every difference of 50mAh, and realize the screening and grouping of the battery.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (7)

1. The method for realizing battery screening grouping in one step is characterized by comprising the following steps of:

1) selecting a certain system of battery, charging and discharging for the first time for one week, and recording the charging and discharging capacity C, C' of the battery;

2) the battery is discharged to a certain voltage V after being pre-charged to full charge₁Recording the charging capacity C₀And V₁；

3) The battery is kept stand and the voltage V after depolarization is recorded₂And time T₁；

4) Standing the battery, and recording the voltage V after the voltage drop of the battery₃And time T₂；

5) The grades are divided by the battery capacity, the depolarization degree and the self-discharge voltage drop.

2. The method for realizing the battery sieve grouping according to the claim 1, wherein: calculating the first efficiency I = C '/C100% of the system battery by using C, C' in step 1).

3. The method for realizing the battery sieve grouping according to the claim 1, wherein: and 2) discharging after the battery is precharged to full charge by adopting a current of 0.1-10C.

4. The method for realizing the battery sieve grouping according to the claim 1, wherein: voltage V in step 2)₁3.6V to 4.1V, using a charge capacity C₀And V₁Calculating the battery capacity C₁=C₀*I。

5. The method for realizing the battery sieve grouping according to the claim 1, wherein: in the step 3), the battery standing temperature is 25-55 ℃, the battery stands for 0-4 h, and the voltage V is utilized₁And a voltage V₂Calculating the voltage variation K₁=（V₂-V₁）。

6. The method for realizing the battery sieve grouping according to the claim 1, wherein: in the step 4), the battery standing temperature is 25-55 ℃, the battery stands for 4-24 h, and the voltage V is utilized₃And time T₂Calculating the change of voltage over time K₂=（V₃-V₂）/（T₂-T₁）。

7. The method for realizing the battery sieve grouping according to the claim 1, wherein: grading the battery in the step 5) by adopting battery discharge capacity C' and depolarization degree K₁=（V₂-V₁) And self-discharge voltage drop K₂=（V₃-V₂）/（T₂-T₁）。

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