CN104190639A

CN104190639A - Self-discharge screening method of lithium ion batteries

Info

Publication number: CN104190639A
Application number: CN201410381371.9A
Authority: CN
Inventors: 侯峰; 林斯辉; 王飞
Original assignee: JIANGXI CHANG HE NEW BATTERY CO Ltd
Current assignee: JIANGXI CHANG HE NEW BATTERY CO Ltd
Priority date: 2014-07-29
Filing date: 2014-07-29
Publication date: 2014-12-10

Abstract

The invention discloses a self-discharge screening method of lithium ion batteries. The self-discharge screening method of the lithium ion batteries comprises the following steps: (1) pretreating, namely, testing the voltages of full (half)-electricity lithium batteries put before and after by adopting a voltage internal resistance tester, recording the voltage data value OCV1 after putting and the voltage data value OCV2 after putting again, determining the critical value U0 of the voltage level at the same period of OCV2, calculating to obtain that batteries with OCV2 smaller than U0 are serious self-discharged batteries, and removing the serious self-discharged batteries; (2) screening the self-discharged batteries according to the voltage difference of the pretreated full (half)-electricity lithium batteries after putting and putting again by adopting a'3 Sigma' circulation removing method. The self-discharge screening method of the lithium ion batteries can be used for calculating for lithium ion battery production manufacturers in batches, and the production efficiency and the product shipment quality are improved greatly.

Description

A kind of lithium ion battery self discharge screening technique

Technical field

The present invention relates to a kind of lithium ion battery self discharge screening technique, be specially adapted to the self discharge under full (partly) the electric state of lithium ion battery to select.

Background technology

It is high that lithium battery has specific energy, self-discharge rate is low, high temperature performance is good and to discharge and recharge the life-span long, the features such as memory-less effect, be widely used at present notebook computer, video camera, digital camera, personal digital assistant (PDA), on the products such as communication terminal product and electric tool, many products need be used more piece cell serial or parallel connection, to reach higher output voltage and capacity, each batch of battery capacity in technique and preparation process, internal resistance, the performances such as self-discharge rate are variant, the basically identical cell of screenability is to form battery pack key link, wherein most important to the screening of monomer self-discharge battery, a kind of simple, accurate self discharge screening technique can reduce shipment risk for lithium battery manufacturer, improve the quality of products, and for lithium ion self discharge selection method, have complexity at present, the problem that False Rate is high.

Summary of the invention

Object of the present invention aims to provide a kind of lithium ion battery self discharge screening technique, can be simply, fast, the screening to self discharge under full (partly) the electric state of lithium ion battery accurately.

For achieving the above object, lithium ion battery self discharge screening technique of the present invention is completed by two steps below.

1, pretreatment, adopt voltage internal resistance test device to carry out voltage tester to full (partly) the electric lithium battery before and after shelving, the voltage data value of record after shelving be OCV1 and shelve again after voltage data value be OCV2, the critical value of determining OCV2 synchronous voltage level is U0, the battery that calculates OCV2 < U0 is serious self-discharge battery, rejects;

2, pretreated full (partly) electric lithium battery is shelved after and shelve again after voltage difference adopt " 3 σ " circulation elimination method to screen self-discharge battery.

Battery to OCV2 >=U0, calculate full (partly) electricity and shelve front and back voltage difference (Δ OCV=OCV1-OCV2), Δ OCV is asked to its Average (pressure drop mean value), Stdev (pressure drop variance), USL=Average (pressure drop mean value)+3*Stdev (pressure drop variance), LSL=Average (pressure drop mean value)-3*Stdev (pressure drop variance), the value of rejecting Δ OCV is greater than USL and is less than the record of LSL, to the battery record of residue Δ OCV by above requirement cycle calculations N time, when Average (pressure drop mean value) N value stops circulation with Average (pressure drop mean value) when (N-1) value equates, now, to the battery of time OCV2 >=U0 by the gross, the record of Δ OCV value >=Average (pressure drop mean value) N+3*Stdev (pressure drop variance) N is labeled as slight self-discharge battery.

Advantage of the present invention is: be different from that common full (partly) electricity is shelved rear voltage and voltage difference self discharge definite value is selected mode, voltage difference employing " 3 σ " circulation elimination method, accurately screens self-discharge battery.

Accompanying drawing explanation

Fig. 1 is that one batch of full electricity is shelved rear voltage distribution.

Fig. 2 is that before and after one batch of full electricity is shelved, voltage difference is that to shelve rear voltage with full electricity be that OCV2 distributes to Δ OCV=OCV1-OCV2.

Fig. 3 is the normal distribution of the poor Δ OCV of cell voltage of OCV2 >=4110mV before and after one batch of full electricity is shelved.

Wherein: 1 and 2, be serious self-discharge battery, 3, be slight self-discharge battery, 4, be non-self-discharge battery.

The specific embodiment

The one batch of full electric battery screening of take is example: select one batch of lithium ion battery, lithium ion battery self discharge screening technique is elaborated.

2nd district self-discharge battery screening in 1st district in Fig. 1 and Fig. 2: one batch of lithium ion battery is precharged to 4.2V with 0.2C, and at 45 ± 3 ℃ of high temperature ageings after 3 days, normal temperature storage for the first time 1 day, detect open-circuit voltage, be designated as OCV1, normal temperature storage for the second time 10 days, detects open-circuit voltage, is designated as OCV2; Voltage change after normal temperature storage is for the second time analyzed, determined the critical value U0 that synchronous voltage changes, the cell voltage of the OCV2 < 4110mV in Fig. 1 declines very fast, rejects this part for serious self-discharge battery.

3rd district self-discharge battery screening in Fig. 2: the battery to OCV2 >=4110mV, obtain for the first time Average (pressure drop mean value), the Stdev (pressure drop variance) of these type of all Δ OCV and be designated as respectively Average (pressure drop mean value) 1, Stdev (pressure drop variance) 1, and calculating USL1=Average (pressure drop mean value) 1+3*Stdev (pressure drop variance) 1, LSL1=Average (pressure drop mean value) 1-3*Stdev (pressure drop variance) 1.The value of rejecting Δ OCV is greater than USL1 and is less than the record of LSL1.Record to residue Δ OCV calculates Average (pressure drop mean value) for the second time, Stdev (pressure drop variance) is also designated as respectively Average (pressure drop mean value) 2, Stdev (pressure drop variance) 2, USL2=Average (pressure drop mean value) 2+3*Stdev (pressure drop variance) 2, LSL2=Average (pressure drop mean value) 2-3*Stdev (pressure drop variance) 2, the value of rejecting Δ OCV is greater than USL2 and is less than the record of LSL2, residue record circulates N time successively, when Average (pressure drop mean value) N value stops circulation with Average (pressure drop mean value) when (N-1) value equates, now, to the battery of time OCV2 >=4110mV by the gross, the record of Δ OCV value >=Average (pressure drop mean value) N+3*Stdev (pressure drop variance) N is labeled as slight self-discharge battery.

Claims

1. a lithium ion battery self discharge screening technique, it is characterized in that (1) pretreatment, adopt voltage internal resistance test device to carry out voltage tester to full (partly) the electric lithium battery before and after shelving, the voltage data value of record after shelving be OCV1 and shelve again after voltage data value be OCV2, the critical value of determining OCV2 synchronous voltage level is U0, the battery that calculates OCV2 < U0 is serious self-discharge battery, rejects, (2) pretreated full (partly) electric lithium battery is shelved after and shelve again after voltage difference adopt " 3 σ " circulation elimination method to screen self-discharge battery, battery to OCV2 >=U0, calculate full (partly) electricity and shelve front and back voltage difference, Δ OCV=OCV1-OCV2, Δ OCV is asked to its Average (pressure drop mean value), Stdev (pressure drop variance), USL=Average (pressure drop mean value)+3*Stdev (pressure drop variance), LSL=Average (pressure drop mean value)-3*Stdev (pressure drop variance), the value of rejecting Δ OCV is greater than USL and is less than the record of LSL, to the battery record of residue Δ OCV by above requirement cycle calculations N time, when Average (pressure drop mean value) N value stops circulation with Average (pressure drop mean value) when (N-1) value equates, now, to the battery of time OCV2 >=U0 by the gross, the record of Δ OCV value >=Average (pressure drop mean value) N+3*Stdev (pressure drop variance) N is labeled as slight self-discharge battery.

2. lithium ion battery self discharge screening technique according to claim 1, it is characterized in that one batch of lithium ion battery to be precharged to 4.2V with 0.2C, and at 45 ± 3 ℃ of high temperature ageings after 3 days, normal temperature storage for the first time 1 day, detect open-circuit voltage, be designated as OCV1, normal temperature storage for the second time 10 days, detect open-circuit voltage, be designated as OCV2, voltage change after normal temperature storage is for the second time analyzed, determined the critical value U0 that synchronous voltage changes, the cell voltage of OCV2 < 4110mV declines very fast, rejects this part for serious self-discharge battery, battery to OCV2 >=4110mV, obtain for the first time the Average (pressure drop mean value) of these type of all Δ OCV, Stdev (pressure drop variance) is also designated as respectively Average (pressure drop mean value) 1, Stdev (pressure drop variance) 1, and calculate USL1=Average (pressure drop mean value) 1+3*Stdev (pressure drop variance) 1, LSL1=Average (pressure drop mean value) 1-3*Stdev (pressure drop variance) 1, the value of rejecting Δ OCV is greater than USL1 and is less than the record of LSL1, record to residue Δ OCV calculates Average (pressure drop mean value) for the second time, Stdev (pressure drop variance) is also designated as respectively Average (pressure drop mean value) 2, Stdev (pressure drop variance) 2, USL2=Average (pressure drop mean value) 2+3*Stdev (pressure drop variance) 2, LSL2=Average (pressure drop mean value) 2-3*Stdev (pressure drop variance) 2, the value of rejecting Δ OCV is greater than USL2 and is less than the record of LSL2, residue record circulates N time successively, when Average (pressure drop mean value) N value stops circulation with Average (pressure drop mean value) when (N-1) value equates, now, to the battery of time OCV2 >=4110mV by the gross, the record of Δ OCV value >=Average (pressure drop mean value) N+3*Stdev (pressure drop variance) N is labeled as slight self-discharge battery.