CN117452235A - Lithium ion battery electrolyte leakage early warning method and system - Google Patents

Lithium ion battery electrolyte leakage early warning method and system Download PDF

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Publication number
CN117452235A
CN117452235A CN202311777782.5A CN202311777782A CN117452235A CN 117452235 A CN117452235 A CN 117452235A CN 202311777782 A CN202311777782 A CN 202311777782A CN 117452235 A CN117452235 A CN 117452235A
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lithium ion
ion battery
preset value
battery pack
soc
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CN117452235B (en
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刘现军
李燕飞
徐开文
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Nanchang University
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Nanchang University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/367—Software therefor, e.g. for battery testing using modelling or look-up tables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/378—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC] specially adapted for the type of battery or accumulator
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
    • G01R31/3842—Arrangements for monitoring battery or accumulator variables, e.g. SoC combining voltage and current measurements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4228—Leak testing of cells or batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a method and a system for early warning of electrolyte leakage of a lithium ion battery, wherein the method firstly obtains a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack, then sequentially obtains data such as the maximum battery pressure difference when the SOC value of the lithium ion battery pack is a first preset value, the average current of the lithium ion battery pack and the like, calculates to obtain an external resistance when the maximum battery pressure difference is in a linear relation with the increase of charge and discharge cycle times, judges that the lithium ion battery has electrolyte leakage faults when the absolute value of the external resistance exceeds a resistance threshold value, and gives out early warning.

Description

Lithium ion battery electrolyte leakage early warning method and system
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a method and a system for early warning of electrolyte leakage of a lithium ion battery.
Background
Lithium ion batteries are widely used in electric vehicles as secondary rechargeable batteries due to their excellent characteristics such as high specific energy and long cycle life. However, with the popularization and application of electric vehicles, electric vehicles also face more and more safety problems, such as continuous aging of batteries (lithium precipitation, thickening of SEI film, increase of internal resistance), electric abuse (overshoot, overdischarge, short circuit), mechanical abuse (extrusion, collision) and thermal abuse, which have adverse effects on the safety of batteries, and even cause serious consequences such as fire explosion due to thermal runaway. Therefore, on-line, accurate health monitoring and fault diagnosis of the battery of the electric automobile are necessary.
At present, in the use process of a lithium ion battery, electrolyte leakage is a battery failure mode which is difficult to find in advance, when a certain battery monomer in a battery pack is leaked for a period of time, external short circuit is formed due to electrochemical corrosion, side reaction of the battery is extremely easy to be induced, a large amount of heat is instantaneously generated, and the safety of other surrounding battery monomers is further affected. However, there is currently a lack of effective electrolyte leakage warning techniques.
Disclosure of Invention
According to the method for early warning of electrolyte leakage of the lithium ion battery, the early warning of electrolyte leakage is achieved, and the safety of battery use is improved.
A lithium ion battery electrolyte leakage early warning method comprises the following steps:
acquiring a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack;
when the cell number corresponding to the minimum cell voltage is kept unchanged in one charge-discharge cycle, obtaining the maximum cell pressure difference when the SOC value of the lithium ion battery pack is a first preset value;
when the maximum battery pressure difference linearly changes along with the increase of the charge-discharge cycle times, acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle;
according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value, the consumed electric quantity of the lithium ion battery pack is obtained;
obtaining average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value;
calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage;
when the absolute value of the external resistor exceeds the resistance threshold, the electrolyte leakage fault of the lithium ion battery is judged, and an early warning is sent out.
According to the early warning method for the electrolyte leakage of the lithium ion battery, provided by the invention, the change rule of the battery voltage and the external resistance caused by the electrolyte leakage is determined, the electrolyte leakage problem of the lithium ion battery is converted into a quantifiable mathematical problem to carry out quantitative diagnosis, the early prediction of the electrolyte leakage fault is realized, the problem that the electrolyte leakage is difficult to identify in the long-time abuse process of the lithium ion battery is solved, and the use safety of the battery is improved.
In addition, the lithium ion battery electrolyte leakage early warning method provided by the invention has the following technical characteristics:
further, a charging capacity C is charged from a first preset value to a second preset value according to the SOC value of the lithium ion battery pack cha And discharging the SOC value of the lithium ion battery pack from the second preset value to the discharge capacity of the first preset value to obtain the consumed electric quantity of the lithium ion battery packIn the step, the power consumption of the lithium ion battery pack is calculated by adopting the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
Further, in the step of obtaining the average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value, the average current of the lithium ion battery pack is calculated by adopting the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch And the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value is represented.
Further, calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage, wherein in the step of calculating the external resistance, the external resistance is calculated by adopting the following formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
Further, the first preset value is 80%, the second preset value is 90%, and the resistance threshold is 50Ω.
The invention further provides a lithium ion battery electrolyte leakage early warning system to realize electrolyte leakage early warning and improve the safety of battery use.
A lithium ion battery electrolyte leakage early warning system, comprising:
the first acquisition module is used for acquiring a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack;
the second acquisition module is used for obtaining the maximum battery pressure difference when the SOC value of the lithium ion battery pack is a first preset value when the battery cell number corresponding to the minimum battery cell voltage is kept unchanged in one charge-discharge cycle;
the third acquisition module is used for acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle when the maximum battery pressure difference changes linearly along with the increase of the charge-discharge cycle times;
the fourth acquisition module is used for acquiring the consumed electric quantity of the lithium ion battery pack according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value;
the fifth acquisition module is used for obtaining average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the lithium ion battery pack from the first preset value to the second preset value and the discharging time of the lithium ion battery pack from the second preset value to the first preset value;
the calculation module is used for calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage;
and the judging and early warning module is used for judging that the electrolyte leakage fault occurs in the lithium ion battery and sending out early warning when the absolute value of the external resistor exceeds the resistance threshold value.
According to the lithium ion battery electrolyte leakage early warning system provided by the invention, the change rule of the battery voltage and the external resistance caused by electrolyte leakage is determined, the electrolyte leakage problem of the lithium ion battery is converted into a quantifiable mathematical problem to quantitatively diagnose, the early prediction of electrolyte leakage faults is realized, the problem that the electrolyte leakage is difficult to identify in the long-time abuse process of the lithium ion battery is solved, and the use safety of the battery is improved.
In addition, the lithium ion battery electrolyte leakage early warning system provided by the invention has the following technical characteristics:
further, the fourth obtaining module is specifically configured to calculate the power consumption of the lithium ion battery pack by adopting the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
Further, the fifth obtaining module is specifically configured to calculate an average current of the lithium ion battery pack by adopting the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch Discharge representing discharge of SOC value of lithium ion battery pack from second preset value to first preset valueTime.
Further, the calculating module is specifically configured to calculate the external resistance using the following formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
Further, the first preset value is 80%, the second preset value is 90%, and the resistance threshold is 50Ω.
Drawings
Fig. 1 is a flowchart of a method for early warning of leakage of electrolyte of a lithium ion battery according to a first embodiment of the present invention;
fig. 2 is a block diagram of a system for early warning of leakage of electrolyte in a lithium ion battery according to a second embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, a first embodiment of the present invention provides a method for early warning of leakage of electrolyte of a lithium ion battery, comprising the following steps S1 to S7:
s1, obtaining a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack.
And S2, when the cell number corresponding to the minimum cell voltage is kept unchanged in one charge-discharge cycle, obtaining the maximum cell pressure difference when the SOC value of the lithium ion battery pack is a first preset value.
Preferably, the first preset value is 80%.
And S3, when the maximum battery pressure difference is linearly changed along with the increase of the charge-discharge cycle times, acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from the first preset value to the second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle.
Preferably, the second preset value is 90%, and it is understood that the first preset value and the second preset value may be other values if the second preset value is greater than the first preset value.
In addition, it should be noted that, in the present embodiment, the maximum battery pressure difference changes linearly with the increase of the charge-discharge cycle number, which means that the linear correlation coefficient of the maximum battery pressure difference and the charge-discharge cycle number is not less than 90%.
And S4, obtaining the consumed electric quantity of the lithium ion battery pack according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value.
The power consumption of the lithium ion battery pack is calculated by adopting the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
And S5, obtaining the average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the lithium ion battery pack from the first preset value to the second preset value and the discharging time of the lithium ion battery pack from the second preset value to the first preset value.
Wherein, the average current of the lithium ion battery pack is calculated by adopting the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch And the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value is represented.
S6, calculating the average voltage of the minimum battery cell voltage in the process that the SOC value of the lithium ion battery pack is charged from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage.
Wherein, the external resistance is calculated using the following formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
And S7, when the absolute value of the external resistor exceeds a resistor threshold, judging that the lithium ion battery has electrolyte leakage fault, and giving out early warning.
Preferably, the resistance threshold is 50Ω. It should be noted that the resistance threshold may also be other resistance values.
The method of this example was verified as follows, and the experiment was designed as follows: the method comprises the steps of sequentially numbering 40 battery cells, connecting the 40 battery cells in series to form a lithium ion battery pack, wherein the capacity of each battery cell is 108Ah, wherein the battery cell with the number 22 is a battery cell with electrolyte leakage through manual treatment, then carrying the lithium ion battery pack on an electric vehicle to serve as a power battery, operating the electric vehicle, obtaining the absolute value of the external resistance of the lithium ion battery pack to be 48 omega according to the method, judging that the lithium ion battery has electrolyte leakage fault, and giving out early warning, wherein the result is consistent with the experimental design, and the battery cell with the number 22 is a battery cell corresponding to the minimum battery cell voltage in a charge-discharge cycle among the 40 battery cells.
In summary, according to the method for early warning leakage of the electrolyte of the lithium ion battery provided by the embodiment, the change rule of the battery voltage and the external resistance caused by the leakage of the electrolyte is determined, the problem of leakage of the electrolyte of the lithium ion battery is converted into a quantifiable mathematical problem to quantitatively diagnose, the early prediction of the failure of the leakage of the electrolyte is realized, the problem that the leakage of the lithium ion battery is difficult to identify in the long-time abuse process is solved, and the use safety of the battery is improved.
Referring to fig. 2, a second embodiment of the present invention provides a leakage early warning system for an electrolyte of a lithium ion battery, including:
the first acquisition module is used for acquiring a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack;
the second acquisition module is used for obtaining the maximum battery pressure difference when the SOC value of the lithium ion battery pack is a first preset value when the battery cell number corresponding to the minimum battery cell voltage is kept unchanged in one charge-discharge cycle;
the third acquisition module is used for acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle when the maximum battery pressure difference changes linearly along with the increase of the charge-discharge cycle times;
the fourth acquisition module is used for acquiring the consumed electric quantity of the lithium ion battery pack according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value;
the fifth acquisition module is used for obtaining average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the lithium ion battery pack from the first preset value to the second preset value and the discharging time of the lithium ion battery pack from the second preset value to the first preset value;
the calculation module is used for calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage;
and the judging and early warning module is used for judging that the electrolyte leakage fault occurs in the lithium ion battery and sending out early warning when the absolute value of the external resistor exceeds the resistance threshold value.
In this embodiment, the fourth obtaining module is specifically configured to calculate the power consumption of the lithium ion battery pack by adopting the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
In this embodiment, the fifth obtaining module is specifically configured to calculate an average current of the lithium ion battery pack by adopting the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch And the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value is represented.
In this embodiment, the calculating module is specifically configured to calculate the external resistance by using the following formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
In this embodiment, the first preset value is 80%, the second preset value is 90%, and the resistance threshold is 50Ω.
In summary, according to the lithium ion battery electrolyte leakage early warning system provided by the embodiment, the change rule of the battery voltage and the external resistance caused by electrolyte leakage is determined, the electrolyte leakage problem of the lithium ion battery is converted into a quantifiable mathematical problem to quantitatively diagnose, the early prediction of electrolyte leakage faults is realized, the problem that the electrolyte leakage is difficult to identify in the long-time abuse process of the lithium ion battery is solved, and the use safety of the battery is improved.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.

Claims (10)

1. The lithium ion battery electrolyte leakage early warning method is characterized by comprising the following steps of:
acquiring a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack;
when the cell number corresponding to the minimum cell voltage is kept unchanged in one charge-discharge cycle, obtaining the maximum cell pressure difference when the SOC value of the lithium ion battery pack is a first preset value;
when the maximum battery pressure difference linearly changes along with the increase of the charge-discharge cycle times, acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle;
according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value, the consumed electric quantity of the lithium ion battery pack is obtained;
obtaining average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value;
calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage;
when the absolute value of the external resistor exceeds the resistance threshold, the electrolyte leakage fault of the lithium ion battery is judged, and an early warning is sent out.
2. The method for pre-warning of leakage of electrolyte of lithium ion battery according to claim 1, wherein the charging capacity C is charged from a first preset value to a second preset value according to the SOC value of the lithium ion battery pack cha And SOC value slave of lithium ion battery packIn the step of discharging the second preset value to the discharge capacity of the first preset value to obtain the consumed electric quantity of the lithium ion battery pack, the consumed electric quantity of the lithium ion battery pack is calculated by adopting the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
3. The method for early warning of leakage of electrolyte of lithium ion battery according to claim 2, wherein in the step of obtaining the average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack and the charging time of the SOC value of the lithium ion battery pack from the first preset value to the second preset value and the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value, the average current of the lithium ion battery pack is calculated by adopting the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch And the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value is represented.
4. The method for early warning of leakage of lithium ion battery electrolyte according to claim 3, wherein in the step of calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum cell voltage, the average voltage of the minimum cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value is calculated, the external resistance is calculated by the following formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
5. The method for early warning of leakage of electrolyte of a lithium ion battery according to claim 1, wherein the first preset value is 80%, the second preset value is 90%, and the resistance threshold is 50Ω.
6. The utility model provides a lithium ion battery electrolyte weeping early warning system which characterized in that includes:
the first acquisition module is used for acquiring a battery cell number corresponding to the minimum battery cell voltage of the lithium ion battery pack;
the second acquisition module is used for obtaining the maximum battery pressure difference when the SOC value of the lithium ion battery pack is a first preset value when the battery cell number corresponding to the minimum battery cell voltage is kept unchanged in one charge-discharge cycle;
the third acquisition module is used for acquiring the charge capacity and the charge time of the SOC value of the lithium ion battery pack from a first preset value to a second preset value and the discharge capacity and the discharge time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value in the same charge-discharge cycle when the maximum battery pressure difference changes linearly along with the increase of the charge-discharge cycle times;
the fourth acquisition module is used for acquiring the consumed electric quantity of the lithium ion battery pack according to the charging capacity of the lithium ion battery pack from the first preset value to the second preset value and the discharging capacity of the lithium ion battery pack from the second preset value to the first preset value;
the fifth acquisition module is used for obtaining average current of the lithium ion battery pack according to the consumed electric quantity of the lithium ion battery pack, the charging time of the lithium ion battery pack from the first preset value to the second preset value and the discharging time of the lithium ion battery pack from the second preset value to the first preset value;
the calculation module is used for calculating the average voltage of the minimum battery cell voltage in the process of charging the SOC value of the lithium ion battery pack from the first preset value to the second preset value, and calculating the external resistance according to the average current of the lithium ion battery pack and the average voltage of the minimum battery cell voltage;
and the judging and early warning module is used for judging that the electrolyte leakage fault occurs in the lithium ion battery and sending out early warning when the absolute value of the external resistor exceeds the resistance threshold value.
7. The system of claim 6, wherein the fourth obtaining module is specifically configured to calculate the power consumption of the lithium ion battery pack by using the following formula:
Q=(C cha -C dch ）×ΔSOC；
ΔSOC=SOC 2 -SOC 1 ；
wherein Q represents the consumed electric quantity of the lithium ion battery pack, C cha C represents a charging capacity of the lithium ion battery pack from a first preset value to a second preset value in the SOC value dch Represents the discharge capacity of the lithium ion battery pack from the second preset value to the first preset value, delta SOC represents the SOC interval, and SOC 1 Representing a first preset value, SOC 2 Representing a second preset value.
8. The system of claim 7, wherein the fifth acquisition module is specifically configured to calculate an average current of the lithium ion battery pack using the following formula:
I=Q/(T cha +T dch )；
wherein I represents average current of the lithium ion battery pack, T cha Representing charging time of SOC value of lithium ion battery pack from first preset value to second preset value, T dch And the discharging time of the SOC value of the lithium ion battery pack from the second preset value to the first preset value is represented.
9. The lithium ion battery electrolyte leakage pre-warning system of claim 8, wherein the calculation module is specifically configured to calculate the external resistance using the formula:
R=U/I；
U=mean(U 1 , U 2 )
wherein R represents an external resistance, U represents a mean voltage of a minimum cell voltage, mean represents a mean operation, U 1 Representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a first preset value, U 2 And representing the minimum cell voltage when the SOC value of the lithium ion battery pack is a second preset value.
10. The lithium ion battery electrolyte leakage pre-warning system of claim 6, wherein the first preset value is 80%, the second preset value is 90%, and the resistance threshold is 50Ω.
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