CN103302040A - Screening method for lithium-ion battery consistency - Google Patents

Abstract

The invention relates to the technical field of the detection of a battery, and in particular relates to a screening method for lithium-ion battery consistency. The method is characterized in that the screening is carried out according to the limit capacity, the limit internal resistance and the limit voltage droop in a high-temperature environment, a low-temperature environment or a normal-temperature environment of a single battery; the battery is charged and discharged, so that the screening can be further carried out by comparing the variation of the capacity, the voltages and the currents in the charging and discharging processes, the application efficiency of the single battery can be improved, the service life of the single battery can be prolonged, and the safety of the single battery can be improved.

Description

The conforming screening technique of lithium ion battery

Technical field

The present invention relates to the battery detecting technical field, particularly relate to the conforming screening technique of a kind of lithium ion battery.

Background technology

At present, has energy density high, long service life, being widely used of the green power supply that security performance is good----lithium ion battery.Lithium ion battery is widely used in the fields such as energy storage, power.Test is found, the same battery of making, and will be lower than the service life of cell the service life of battery pack, and this explanation battery consistency obviously affects the service life of battery.In the connection in series-parallel of battery was used, the consistency problem of battery affected efficient and the life-span of battery, and safety problem is also influential.So the conforming requirement that combines the cell of battery pack should be stricter.

Guarantee the uniformity of battery, will guarantee that at first every initial performance of battery is consistent, the self discharge of battery will be consistent, and fading rate in use will be consistent.The conforming screening of current battery mainly is to utilize under normal temperature, low temperature and the hot environment battery capacity, internal resistance, voltage, discharge and recharge discharge platform and self discharge difference is screened.

The battery that screens falls by different temperatures lower limit constant volume scope, restriction internal resistance scope and stop voltage, can guarantee that battery initial performance, self-discharge performance are consistent, do not verify whether battery discharging and recharging in the process of using be synchronous, can not guarantee that fading rate in use is consistent.Reason is, the screening technique of existing battery can not reflect cell DC internal resistance and polarization resistance, and there is defective in the uniformity of battery.

The lithium ion battery group is to be formed by connecting through connection in series-parallel by a plurality of cells, but because the performance of each cell there are differences, the performance of battery pack is through having decline in various degree after certain charge and discharge cycles, show as that the conforming difference of monomer battery core becomes large in the acceleration of capacity attenuation and the battery pack, therefore must carry out strict selecting at battery before in groups.If the uniformity of cell is bad, charge and discharge process can strengthen the difference between the monomer battery core so, easily cause the part battery over-discharge or overcharge, and the performance of another part battery also can not get fully playing, finally cause the deteriorated of battery performance, the decay of battery pack cycle performance or inefficacy.

As everyone knows, the uniformity that how to guarantee each cell in the battery pack is the key that guarantees battery performance, also is that present lithium ion battery is at the bottleneck of various fields successful Application.

Summary of the invention

The purpose of this invention is to provide the conforming screening technique of a kind of lithium ion battery, it can guarantee under the state of work, and the charging and discharging state of lithium ion single battery that forms battery pack is synchronous, further improves the uniformity of battery.

Method of the present invention is to fall and screen according to the restriction capacity under cell high temperature, low temperature or the normal temperature varying environment, restriction internal resistance, stop voltage;

Battery discharges and recharges, and relatively capacity, voltage, curent change are done further screening in the charge and discharge process.

Method concrete steps of the present invention are as follows:

Filter out the lithium ion single battery of under equal conditions producing, namely the raw material of battery form and the preparation technology of battery waits and wants unanimously;

Battery is carried out outward appearance to be screened: battery must without flatulence, qualified without leakage, surface nothing scuffing and apparent size, filter out the qualified battery of outward appearance;

The qualified battery that filters out at room temperature under 20～30 ℃, is shelved preheating setting time: 14～28 days;

According to cell high temperature: 40～60 ℃, low temperature :-40～0 ℃ or normal temperature: the capacity under 20～30 ℃ the varying environment, internal resistance, voltage drop are added up and are screened;

Measure capacity, internal resistance, the voltage drop of standby screening battery under different temperature ranges;

Measured capacity, internal resistance and voltage drop out averaged;

Be greater than or less than the battery of the predetermined percentage of capacity, internal resistance, voltage drop mean value, be judged to be unusual battery, rejected;

The battery that previous step is not rejected carries out discharging and recharging of Work condition analogue, the charging and discharging currents scope is at 0.1～3C, capacity, voltage or current measurement data in the discharge process are derived, be drawn as curve map, the variation tendency of the capacity among the analytic curve figure, voltage or electric current is progressively rejected the battery that curve distribution is unusual.

The present invention has the following advantages compared with prior art:

The present invention can improve service efficiency, service life and the security of cell by being further to screen synchronously to capacity, voltage, electric current in the charge and discharge process of cell.

Description of drawings

Fig. 1 is screening process figure of the present invention,

Fig. 2 is 27 battery discharge voltage change curve distribution figure of the embodiment of the invention,

Fig. 3 is 16 battery discharge voltage change curve distribution figure of the embodiment of the invention,

Fig. 4 is 10 battery discharge voltage change curve distribution figure of the embodiment of the invention.

The specific embodiment

Method concrete steps of the present invention are as follows:

Filter out the lithium ion single battery of under equal conditions producing, namely the raw material of battery form and the preparation technology of battery waits and wants unanimously;

Battery is carried out outward appearance to be screened: battery must without flatulence, qualified without leakage, surface nothing scuffing and apparent size, filter out the qualified battery of outward appearance;

The qualified battery that filters out at room temperature under 20～30 ℃, is shelved preheating setting time: 14～28 days;

According to cell high temperature: 40～60 ℃, low temperature :-40～0 ℃ or normal temperature: the capacity under 20～30 ℃ the varying environment, internal resistance, voltage drop are added up and are screened;

Measure capacity, internal resistance, the voltage drop of standby screening battery under different temperature ranges;

Measured capacity, internal resistance and voltage drop out averaged;

Be greater than or less than the battery of the predetermined percentage of capacity, internal resistance, voltage drop mean value, be judged to be unusual battery, rejected;

The battery that previous step is not rejected carries out discharging and recharging of Work condition analogue, the charging and discharging currents scope is at 0.1～3C, capacity, voltage or current measurement data in the discharge process are derived, be drawn as curve map, the variation tendency of the capacity among the analytic curve figure, voltage or electric current is progressively rejected the battery that curve distribution is unusual;

To the screening of discharging of the lithium ion of 27 100Ah not rejecting;

The Work condition analogue that battery is discharged with 0.5C, 0.8C and 1C:

The charge-discharge test scheme:

Shelve: 60 seconds

Constant-current discharge: 50A deadline: 10 seconds; Voltage: 2.50V;

Shelve: 60 seconds

Constant-current discharge: 80A deadline: 10 seconds; Voltage: 2.50V;

Shelve: 60 seconds

Constant-current discharge: 100A deadline: 10 seconds; Voltage: 2.50V;

Shelve: stopped in 60 seconds

During Work condition analogue, shelve 3S writing time, electric discharge recording time 1S.

Data derive

Data analysis

Analyze the voltage change in the battery charge and discharge process, 27 batteries that analysis is found to screen carry out primary election 11 batteries that difference is large and give up in the situation that with current discharge, the variation of voltage has very large difference, remain 16 cells;

To the voltage change in the analysis of the battery after the primary election charge and discharge process, carry out two choosings, 6 batteries that difference is large and give up, remain 10 batteries;

Be further analyzed discovery through 10 batteries after two choosings, the variation of voltage in the process that discharges and recharges of remaining battery is consistent, screens complete.

Claims (1)

1. the conforming screening technique of lithium ion battery is characterized in that comprising the steps:

Filter out the lithium ion single battery of under equal conditions producing, namely the raw material of battery form and the preparation technology of battery waits and wants unanimously;

Battery is carried out outward appearance to be screened: battery must without flatulence, qualified without leakage, surface nothing scuffing and apparent size, filter out the qualified battery of outward appearance;

The qualified battery that filters out at room temperature under 20～30 ℃, is shelved preheating setting time: 14～28 days;

According to cell high temperature: 40～60 ℃, low temperature :-40～0 ℃ or normal temperature: the capacity under 20～30 ℃ the varying environment, internal resistance, voltage drop are added up and are screened;

Measure capacity, internal resistance, the voltage drop of standby screening battery under different temperature ranges;

Measured capacity, internal resistance and voltage drop out averaged;

Be greater than or less than the battery of the predetermined percentage of capacity, internal resistance, voltage drop mean value, be judged to be unusual battery, rejected;

The battery that previous step is not rejected carries out discharging and recharging of Work condition analogue, the charging and discharging currents scope is at 0.1～3C, capacity, voltage or current measurement data in the discharge process are derived, be drawn as curve map, the variation tendency of the capacity among the analytic curve figure, voltage or electric current is progressively rejected the battery that curve distribution is unusual.

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