Method for realizing battery screen allocation group in one step

Abstract

The present invention provides a method for realizing battery screening distribution group in one step, including the following steps: 1) Select a battery of a certain system, charge and discharge it for the first time for one week, and record the battery charge and discharge capacity C and C`; 2) The battery is pre-charged to full power and then discharged to a certain voltage V1, and the charge capacity C0 and V1 are recorded; 3) The battery is allowed to stand, and the voltage V2 and time T1 after depolarization are recorded; 4) The battery is allowed to stand, and the voltage V3 and time T2 after the battery voltage drop are recorded; 5) The battery capacity, degree of depolarization, and self-discharge voltage drop are divided into grades. The present invention realizes a method for realizing battery screening distribution group in one step, which can greatly shorten the product production cycle, reduce production costs, and accurately pick out abnormal batteries to realize battery grouping, and provide a new idea for optimizing the existing battery screening distribution group process and determining the new system battery process.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a method for realizing a battery screen distribution group in one step. Background Art

[0002] As people's living standards improve, their requirements for living environment are also increasing. Traditional pollution sources such as nickel-metal hydride, nickel-chromium and lead-acid batteries are gradually being phased out, 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 competition in the industry. Screening and grouping is to remove abnormal batteries and use batteries with similar performance together. It is an important link in lithium battery production and is related to the safety and consistency of battery use. This technology varies greatly among different companies, and most of them have longer production cycles and higher costs. Therefore, as one of the core technologies of lithium battery companies, screening and grouping requires a lot of investment in technology development.

[0003] Traditional screening and grouping often includes multiple processes, such as pre-charging, storage, OCV testing, capacity division, etc. Finally, the battery is graded based on two or three of the data such as capacity, static internal resistance, discharge platform time, charge and discharge efficiency or open circuit voltage to achieve grouping. This process has a long production cycle and is cumbersome to operate, which undoubtedly greatly increases the product cost. Summary of the invention

[0004] The present invention proposes a method for implementing battery screening and grouping in one step, wherein the battery capacity is calculated by the charging capacity and the first efficiency, the battery depolarization degree K1 is calculated by the voltage rebound at the end of discharge, and the battery self-discharge voltage drop K2 value is calculated by the voltage drop before and after shelving. The batteries are screened and grouped in combination with the battery capacity, the depolarization degree K1 and the self-discharge voltage drop K2 value.

[0005] The technical solution for realizing the present invention is:

[0006] A method for implementing a battery screen distribution group in one step comprises the following steps:

[0007] 1) To determine the first efficiency of a battery in a certain system, select a fresh battery after aging in a certain system, charge the battery to full power for the first time, discharge it to the cut-off voltage, cycle it for one cycle, record the battery charge and discharge capacity C and C', and calculate the first efficiency value of the battery in this system I=C' / C*100%. Before the system and process are changed, this value is used for the subsequent calculation of battery capacity;

[0008] 2) After the battery is fully charged, it is discharged to a certain voltage V1. The discharge current is 0.1C-10C, preferably 1C-5C. The voltage should be above the platform voltage, preferably in the range of 3.8-4.0V. Record the charge capacity C0 and V1, and calculate the battery capacity C1=C0*I;

[0009] 3) Place the battery in a 25℃-55℃ environment for 0.1h~4h, preferably 0h~2h, record the voltage V2 and time T1 after depolarization, and calculate the voltage change over time K1=(V2-V1);

[0010] 4) Continue to place the battery in a 25℃-55℃ environment for 4~24h, preferably 12~24h, record the voltage V3 and time T2 after the battery voltage drop, and calculate the voltage change over time K2=(V3-V2) / (T2-T1);

[0011] 5) Classification by battery capacity, depolarization degree, and self-discharge voltage drop;

[0012] The battery classification is based on the battery discharge capacity C`, the degree of depolarization K1= (V2-V1) and the self-discharge voltage drop K2= (V3-V2) / (T2-T1).

[0013] The beneficial effects of the present invention are:

[0014] The present invention calculates the battery capacity through the charging capacity and the first efficiency during the pre-charging process, calculates the battery depolarization degree K1 through the voltage rebound at the end of discharge, calculates the battery self-discharge voltage drop K2 value through the voltage drop before and after shelving, and finally screens and groups the batteries based on the battery capacity, depolarization degree K1 and self-discharge voltage drop K2 value. The invention is scientific and reasonable, simple to operate, and applicable to batteries of different systems. It provides a new idea for optimizing the existing battery screening and grouping process and determining the new system battery process.

[0015] The present invention realizes a method for realizing battery screen allocation group in one step, which can greatly shorten the product production cycle, reduce production costs, and can accurately pick out abnormal batteries to realize battery grouping. It provides a new idea for optimizing the existing battery screen allocation group process and determining the new system battery process. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0017] Figure 1 Select a schematic diagram for the process. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the embodiment, 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. A certain amount of fresh batteries after aging of the system are selected, and the battery is charged and discharged for the first time for one cycle, and the battery charge and discharge capacity C and C' are recorded, and the first effective value of the battery of the system is calculated as I=C' / C*100%=(C1' / C1+C2' / C2+C10' / C10) / 10*100%=87.03%.

[0020]

[0021] Example 1

[0022] After the battery is pre-charged to full power, it is discharged at 0.1C to 3.8V. The charging capacity C0 is recorded as 18.880Ah. The battery capacity C1 is calculated as C0*I=18.880*87.03%=16.431Ah. The battery is placed in a 25℃ environment for 0.1h. The voltage after depolarization V2=3.940V and time T1=0.1h are recorded. The voltage change over time K1=(V2-V1)=3.940-3.8=0.14V is calculated. The battery is placed in a 25℃ environment for 24h and the voltage after the voltage drop V3= 3.937V and time T2=24.1h, calculate the voltage change over time K2=(V3-V2) / (T2-T1)=0.125mV / h, finally, according to the C1, K1 and K2 values, the batteries are screened and allocated to groups, and the abnormal products with a difference of more than 5% between K1 and K2 are eliminated. The remaining battery capacity is divided into a level for every 50mAh difference, so as to realize the screening and allocation of batteries.

[0023] Example 2

[0024] After the battery is pre-charged to full charge, it is discharged at 5C to 3.8V. The charging capacity C0 is recorded, and the battery capacity C1=C0*I is calculated. The battery is placed in a 55℃ environment for 0.1h, and the voltage V2 and time T1 after depolarization are recorded. The voltage change over time K1=(V2-V1) is calculated. Continue to place it in a 55℃ environment for 24h, record the voltage V3 and time T2 after the voltage drop, and calculate the voltage change over time K2=(V3-V2) / (T2-T1). Finally, the batteries are screened and allocated to groups according to the C1, K1 and K2 values, and the abnormal products with a difference of more than 5% between K1 and K2 are eliminated. The remaining battery capacity is divided into one level for every 50mAh difference, so as to realize the screening and allocation of batteries.

[0025] Example 3

[0026] After the battery is pre-charged to full charge, it is discharged at 0.1C to 4.1V, and the charging capacity C0 is recorded. The battery capacity C1=C0*I is calculated. The battery is placed in a 25℃ environment for 0.1h, and the voltage V2 and time T1 after depolarization are recorded. The voltage change over time K1=(V2-V1) is calculated. Continue to place it in a 25℃ environment for 12h, record the voltage V3 and time T2 after the voltage drop, and calculate the voltage change over time K2=(V3-V2) / (T2-T1). Finally, the batteries are screened and allocated to groups according to the C1, K1 and K2 values, and the abnormal products with a difference of more than 5% between K1 and K2 are eliminated. The remaining battery capacity is divided into one level for every 50mAh difference, so as to realize the screening and allocation of batteries.

[0027] Example 4

[0028] After the battery is pre-charged to full charge, it is discharged at 0.1C to 3.9V, and the charging capacity C0 is recorded. The battery capacity C1=C0*I is calculated. The battery is placed in a 25℃ environment for 4h, and the voltage V2 and time T1 after depolarization are recorded. The voltage change over time K1=(V2-V1) is calculated. Continue to place it in a 55℃ environment for 4h, record the voltage V3 and time T2 after the voltage drop, and calculate the voltage change over time K2=(V3-V2) / (T2-T1). Finally, the batteries are screened and allocated to groups according to the C1, K1 and K2 values, and the abnormal products with a difference of more than 5% between K1 and K2 are eliminated. The remaining battery capacity is divided into one level for every 50mAh difference, so as to realize the screening and allocation of batteries.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for implementing a battery screen distribution group in one step, characterized in that: The following steps are involved: 1) Select a fresh battery after aging of a certain system, fully charge and discharge it for a week for the first time, and record the battery charge and discharge capacity C and C`; use the C and C` to calculate the system battery first efficiency I=C` / C*100%; 2) Precharge the fresh battery to full power and then discharge it to a certain voltage V1, record the charge capacity C0 and V1; the voltage V1 is 3.6V~4.1V, use the charge capacity C0 and V1 to calculate the battery capacity C1=C0*I; 3) Step 2) The battery is left to stand, and the voltage V2 and time T1 after depolarization are recorded; 4) Step 3) The battery continues to stand still, and the voltage V3 and time T2 after the battery voltage drop are recorded; 5) The battery is graded according to the battery capacity C1, depolarization degree K1, and self-discharge voltage drop K2; In step 5), the battery classification is based on the battery discharge capacity C1, the depolarization degree K1=(V2-V1) and the self-discharge voltage drop K2=(V3-V2) / (T2-T1); The batteries are screened and grouped according to the C1, K1 and K2 values, and abnormal products with a difference of more than 5% between K1 and K2 are eliminated. The remaining battery capacity is divided into a level for every 50mAh difference, thus realizing the screening and grouping of batteries.

2. The method for realizing the battery screen allocation group in one step according to claim 1, characterized in that: In step 2), the battery is pre-charged to full charge and then discharged using a current of 0.1C to 10C.

3. The method for realizing the battery screen allocation group in one step according to claim 1, characterized in that: In step 3), the battery is kept at a temperature of 25°C to 55°C and for 0h to 4h. The voltage V1 and the voltage V2 are used to calculate the voltage change K1 = (V2-V1).

4. The method for realizing the battery screen allocation group in one step according to claim 1, characterized in that: In step 4), the battery is kept at a temperature of 25°C to 55°C and the battery is kept at a temperature of 4 to 24 hours. Using the voltage V3 and time T2, calculate the voltage change over time K2 = (V3-V2) / (T2-T1).

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