CN105911477B

CN105911477B - Screening method for self-discharge of power lithium ion battery

Info

Publication number: CN105911477B
Application number: CN201610234729.4A
Authority: CN
Inventors: 魏引利; 陈�峰; 王海波; 侯守卫
Original assignee: Gotion High Tech Co Ltd
Current assignee: Gotion High Tech Co Ltd
Priority date: 2016-04-14
Filing date: 2016-04-14
Publication date: 2019-01-22
Anticipated expiration: 2036-04-14
Also published as: CN105911477A

Abstract

The invention relates to a screening method for self-discharge of a power lithium ion battery, which comprises the following steps: selecting a battery with the charge state of 20-80% for formation; sending the battery into a steel ball chamber within 10 minutes after the formation is finished, and sealing the steel balls; cleaning the battery sealed with the steel balls, and measuring the initial alternating internal resistance ACR0 of the battery within 30 minutes after the cleaning is finished; after the battery is placed in an aging room for 72 hours, measuring the AC internal resistance ACR1 of the battery; grading the capacity of the battery, and testing the alternating current internal resistance ACR2 of the battery within 30 minutes after grading the capacity; calculating a battery alternating current internal resistance difference value C1 before capacity grading, a battery internal resistance difference value C2 after capacity grading and a difference value C; the larger values of C1 and C2 and the larger value of the difference C are eliminated. The method screens the self-discharging power lithium ion battery by adopting the change rule of the alternating current internal resistance value after formation and before and after capacity grading, thereby not only saving the production cost and improving the product quality, but also improving the service performance and the cycle life of the battery.

Description

A kind of screening technique of power lithium-ion battery self discharge

Technical field

The present invention relates to lithium ion battery screening technique fields, and in particular to a kind of sieve of power lithium-ion battery self discharge Choosing method.

Background technique

Development of Electric Vehicles surges forward, and Vehicular dynamic battery system is used as wherein most important component part, It has aroused widespread concern in all circles of society and payes attention to.Power lithium-ion battery is because its specific energy is big, have extended cycle life, self discharge is small (comparing lead-acid battery), memory-less effect, can satisfy the need in terms of the passenger car more demanding to volume, service life, power etc. It asks, it has also become the ideal product of pure electric automobile application.But electrokinetic cell system needs multiple single battery core strings and composition, it is single Body battery with two side terminals becomes an important factor for influencing electrokinetic cell system performance, and wherein the consistency of the self discharge of battery becomes An important factor for restricting power lithium-ion battery system service performance and cycle life, effective self discharge screening technique are to solve Because of the main path that battery system fails caused by self discharge greatly.

Summary of the invention

The purpose of the present invention is to provide a kind of screening techniques of power lithium-ion battery self discharge, to solve because of self discharge The problem of causing battery system to fail greatly.

To achieve the above object, the invention adopts the following technical scheme:

A kind of screening technique of power lithium-ion battery self discharge, which comprises the following steps:

(1) battery of the state-of-charge between 20%~80% is chosen to be melted into；

(2) battery feeding steel ball room is subjected to envelope steel ball in 10 minutes after the completion of being melted into；

(3) battery of envelope steel ball is cleaned, measures the initial AC internal Resistance of battery after the completion of cleaning in 30 minutes ACR0；

(4) after battery being put into burn-in chamber 72 hours, the AC internal Resistance ACR1 of battery is measured；

(5) partial volume is carried out to battery, tests the AC internal Resistance ACR2 of battery after partial volume in 30 minutes；

(6) internal resistance of cell difference C2 after battery AC internal Resistance difference C1 and partial volume is calculated before partial volume:

C1=ACR1- ACR0, C2=ACR2- ACR1；

(7) calculating difference C=C1-C2；

(8) value that C1, C2 value and difference C bigger than normal become larger is rejected.

The screening technique of the power lithium-ion battery self discharge, in step (8), rejecting C1 value bigger than normal includes following step It is rapid:

(A) average value of test sample battery AC internal Resistance difference C1 is calculated；

(B) absolute value rejected the battery for being greater than mean deviation ± 5%, while rejecting C1 is greater than the battery of 0.3 milliohm.

In step (8), reject C2 it is bigger than normal value the following steps are included:

(a) average value of test sample battery AC internal Resistance difference C2 is calculated；

(b) absolute value rejected the battery for being greater than mean deviation ± 5%, while rejecting C2 is greater than the battery of 0.3 milliohm.

The screening technique of the power lithium-ion battery self discharge, in step (8), rejecting C value bigger than normal includes following step It is rapid:

(Aa) average value of multiple groups difference C is calculated；

(Ba) absolute value rejected the battery for being greater than mean deviation ± 5%, while rejecting C is greater than the battery of 0.3 milliohm.

The screening technique of the power lithium-ion battery self discharge in above step, is tested in battery measurement process Environment carried out under 23 DEG C of ± 2 DEG C of normal temperature conditions.

The screening technique is suitble to the screening of two kinds of material system power lithium-ion battery self discharges of LFP/C and NCM/C.

As shown from the above technical solution, the screening technique of power lithium-ion battery self discharge of the present invention, using change At the internal resistance value changing rule before and after rear and partial volume, the power lithium of self discharge is screened from battery, is not only saved Production cost improves product quality, while improving the service performance and cycle life of battery.

Specific embodiment

A kind of screening technique of power lithium-ion battery self discharge, comprising the following steps:

S1: the battery that 300 chemical conversions are completed is got from workshop, the charged state of battery is 80% at this time；

S2: battery feeding steel ball room is subjected to envelope steel ball in 10 minutes after the completion of chemical conversion；

S3: the battery of envelope steel ball is cleaned, is tested in 30 minutes with HIKIO3555 internal resistance test device after the completion of cleaning The AC internal Resistance of complete 300 battery cores, is recorded as ACR00-ACR0300；

S4: after battery is put into burn-in chamber 72 hours, 300 battery core partial volumes are tested with HIKIO3555 internal resistance test device Preceding AC internal Resistance, is recorded as ACR10-ACR1300；

S5: partial volume is carried out to battery, the state-of-charge of battery is 80% after partial volume, tests battery in 30 minutes after partial volume AC internal Resistance be recorded as ACR20-ACR2300；

S6: internal resistance of cell difference C2 after battery AC internal Resistance difference C1 and partial volume is calculated before partial volume:

C1=ACR1- ACR0, is recorded as C10-C1300；

C2= ACR2- ACR1；It is recorded as C20-C2300；

S7: calculating difference C=C1-C2 is recorded as C0-C300；

S8: the value that C1, C2 value and difference C bigger than normal become larger is rejected, specific step is as follows:

The average value (C10+ C11++C1300)/300 for calculating C1 is 0.25 milliohm, rejects C1 value and exists Value other than 0.2375 milliohm to 0.2625 milliohm range, while the value for rejecting C1 is greater than the battery of 0.3 milliohm；

The average value (C20+ C21++C2300)/300 for calculating C2 is 0.25 milliohm, rejects C2 value and exists Value other than 0.2375 milliohm to 0.2625 milliohm range, while the value for rejecting C2 is greater than the battery of 0.3 milliohm；

The average value (C20+ C21++C2300)/300 for calculating C is 0.25 milliohm, rejects C value and exists Value other than 0.2375 milliohm to 0.2625 milliohm range, while the value for rejecting C is greater than the battery of 0.3 milliohm.

Embodiment described above only describe the preferred embodiments of the invention, not to model of the invention It encloses and is defined, without departing from the spirit of the design of the present invention, those of ordinary skill in the art are to technical side of the invention The various changes and improvements that case is made should all be fallen into the protection scope that claims of the present invention determines.

Claims

1. a screening method for self-discharge of power lithium ion battery, is characterized in that, comprises the following steps:

(1) Select a battery with a state of charge between 20% and 80% for formation;

(2) Send the battery to the steel ball chamber within 10 minutes after the formation is completed to seal the steel balls;

(3) Clean the battery with the steel ball sealed, and measure the initial AC internal resistance ACR0 of the battery within 30 minutes after the cleaning is completed;

(4) After placing the battery in the aging room for 72 hours, measure the AC internal resistance ACR1 of the battery;

(5) Divide the battery, and test the AC internal resistance ACR2 of the battery within 30 minutes after the capacity is divided;

(6) Calculate the battery AC internal resistance difference C1 before capacity division and the battery internal resistance difference C2 after capacity division:

C1= ACR1- ACR0, C2= ACR2- ACR1;

(7) Calculate the difference C=C1-C2;

(8) Eliminate the larger values of C1 and C2 and the larger value of the difference C;

Among them, removing the large value of C1 includes the following steps:

(A) Calculate the average value of the AC internal resistance difference C1 of the test sample battery;

(B) Cells with a deviation greater than ±5% from the average were excluded, while those with an absolute value of C1 greater than 0.3 milliohms were excluded.

2. The screening method for self-discharge of power lithium-ion batteries according to claim 1, characterized in that: in step (8), removing the larger value of C2 comprises the following steps:

(a) Calculate the average value of the AC internal resistance difference C2 of the test sample battery;

(b) Eliminate batteries with a deviation greater than ±5% from the mean value, and eliminate batteries with an absolute value of C2 greater than 0.3 milliohms.

3 . The screening method for self-discharge of power lithium-ion batteries according to claim 1 , wherein: in step (8), removing a larger value of C comprises the following steps: 4 .

(Aa) Calculate the average value of multiple groups of differences C;

(Ba) Eliminate batteries with a deviation greater than ±5% from the mean value, and eliminate batteries with an absolute value of C greater than 0.3 milliohms.

4 . The screening method for self-discharge of power lithium-ion batteries according to claim 1 , wherein the environment tested in the battery measurement process is carried out under normal temperature conditions of 23° C.±2° C. 5 .

5 . The screening method for self-discharge of power lithium-ion batteries according to claim 1 , wherein the screening method is suitable for the screening of self-discharge of power lithium-ion batteries in two material systems, LFP/C and NCM/C. 6 .