CN111106404B - Floating charge optimization method for lithium iron phosphate battery - Google Patents

Floating charge optimization method for lithium iron phosphate battery Download PDF

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CN111106404B
CN111106404B CN201911205678.2A CN201911205678A CN111106404B CN 111106404 B CN111106404 B CN 111106404B CN 201911205678 A CN201911205678 A CN 201911205678A CN 111106404 B CN111106404 B CN 111106404B
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charging
battery
voltage
floating charge
iron phosphate
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CN111106404A (en
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王世旭
厉运杰
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Hefei Gotion High Tech Power Energy Co Ltd
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Hefei Guoxuan High Tech Power Energy Co Ltd
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    • 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
    • H01M10/44—Methods for charging or discharging
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/44—Methods for charging or discharging
    • H01M10/446—Initial charging measures
    • 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
    • H01M10/44—Methods for charging or discharging
    • H01M10/448—End of discharge regulating measures
    • 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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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides a lithium iron phosphate battery floating charge optimization method, which comprises the following steps: charging the lithium battery by adopting a plurality of charging currents which are reduced in sequence until the voltage of the lithium battery reaches a preset step voltage threshold; then, carrying out floating charging on the lithium battery for a first time value; and then, performing constant current discharge on the lithium battery until the preset cut-off voltage is reached. The invention provides a floating charge optimization method for a lithium iron phosphate battery, which adopts a three-stage charging and discharging mode of 'step charging-floating charge-constant current discharging' in the floating charge recycling process of the lithium iron phosphate battery. And after the floating charge cycle reaches a certain period, deep discharge and constant-current and constant-voltage charging are carried out once, and the deep discharge and constant-current and constant-voltage charging are carried out on the lithium iron phosphate battery periodically by the charging strategy, so that the degradation of active substances is reduced, the floating charge safety performance of the lithium iron phosphate battery is improved, and the cycle service life of the lithium iron phosphate battery is prolonged.

Description

Floating charge optimization method for lithium iron phosphate battery
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a lithium iron phosphate battery floating charge optimization method.
Background
In the field of energy storage, the storage battery is used as an emergency power supply after power failure to provide power for key equipment, the work of key switches and the equipment is guaranteed, the reliability of a system is greatly influenced, and the reliability of the equipment system is directly influenced by the reliability of the storage battery. The traditional storage battery generally adopts a lead-acid battery, and the lead-acid battery has the defects of large maintenance workload, short service life, large influence of temperature on capacity and the like. As system equipment advances and demands higher battery performance, conventional lead-acid batteries become increasingly less suitable. The lithium iron phosphate battery has excellent rate discharge characteristic, higher energy density and stronger temperature adaptability, and thus becomes a good substitute for a lead-acid battery. However, because the storage battery of the storage power station adopts floating charge management, if the charging strategy is unreasonable, the running state of the whole battery can be obviously reduced, and the phenomena of overcharge and overdischarge of the battery are caused, so that the capacity and the service life of the battery are sharply reduced.
Disclosure of Invention
Based on the technical problems in the background art, the invention provides a lithium iron phosphate battery floating charge optimization method.
The invention provides a lithium iron phosphate battery floating charge optimization method, which comprises the following steps:
s1, charging a lithium battery by adopting a plurality of sequentially reduced charging currents until the voltage of the lithium battery reaches a preset step voltage threshold;
s2, carrying out floating charging on the lithium battery for a first time value;
and S3, performing constant current discharge on the lithium battery until a preset cut-off voltage is reached.
Preferably, step S1 specifically includes: the lithium battery is charged to a first voltage value V by adopting a first current value 1 And then the lithium battery is charged to a second voltage value V by adopting a second current value 2 And then the lithium battery is charged to the step voltage threshold V by adopting a third current value in a constant current manner 3 Cutting off; wherein the first current value is greater than the second current value, the second current value is greater than the third current value, V 1 <V 2 <V 3 。
Preferably, V 1 ＝3.4V，V 2 ＝3.45V，V 3 ＝3.5V。
Preferably, the first current value is 0.6C, the second current value is 0.5C, and the third current value is 0.2C.
Preferably, after the voltage of the lithium battery reaches a preset step voltage threshold value, standing for 10s and then performing floating charging.
Preferably, step S2 specifically includes: charging the lithium battery to a preset floating charge voltage threshold value in a constant-current manner, then charging the lithium battery to a constant voltage manner until the charging current is reduced to the preset floating charge current threshold value, and then standing the lithium battery and recording the real-time voltage; and when the real-time voltage is lower than the preset static voltage value, returning to the previous step to continue floating charging, and circulating to the first time value, wherein the static voltage value is smaller than the floating charging voltage threshold value.
Preferably, in step S21, the constant current charging current is 0.1C, the float voltage threshold is 3.65V, the float charging current threshold is 0.01A, and the quiescent voltage value =3.38V.
Preferably, the first time value is 60 days.
Preferably, in step S3, the discharge is performed at a constant current of 0.5C.
Preferably, in step S3, the cut-off voltage is equal to 2.0V.
The invention provides a floating charge optimization method for a lithium iron phosphate battery, which adopts a three-stage charging and discharging mode of 'step charging-floating charge-constant current discharging' in the floating charge recycling process of the lithium iron phosphate battery. And after the floating charge cycle reaches a certain period, deep discharge and constant-current and constant-voltage charging are carried out once, and the deep discharge and constant-current and constant-voltage charging are carried out on the lithium iron phosphate battery periodically by the charging strategy, so that the degradation of active substances is reduced, the floating charge safety performance of the lithium iron phosphate battery is improved, and the cycle service life of the lithium iron phosphate battery is prolonged.
Drawings
Fig. 1 is a flow chart of a lithium iron phosphate battery floating charge optimization method provided by the invention;
fig. 2 is a flow chart of another lithium iron phosphate battery floating charge optimization method provided by the present invention;
fig. 3 is a graph of battery cycle life before and after optimization.
Detailed Description
Referring to fig. 1, in the floating charge optimization method for the lithium iron phosphate battery provided by the invention, a three-stage charging and discharging mode of 'step charging-floating charging-constant current discharging' is adopted in the floating charge cycle process of the lithium iron phosphate battery, and once deep discharging and constant current and constant voltage charging are carried out after the floating charging reaches a certain period.
The lithium iron phosphate battery floating charge optimization method comprises the following steps.
S1, charging the lithium battery by adopting a plurality of charging currents which are reduced in sequence until the voltage of the lithium battery reaches a preset step voltage threshold value.
Specifically, in this step, the lithium battery is charged to the first voltage value V by the constant current with the first current value 1 And then the lithium battery is charged to a second voltage value V by adopting a second current value 2 And then the lithium battery is charged to the step voltage threshold V by adopting a third current value in a constant current manner 3 Cutting off; wherein the first current value is greater than the second current value, the second current value is greater than the third current value, V 1 <V 2 <V 3 。
Specifically, in the present embodiment, the first current value is 0.6C, the second current value is 0.5C, and the third current value is 0.2C.
And S2, carrying out floating charging on the lithium battery for the first time value.
Specifically, referring to fig. 2, in this step, the lithium battery is charged at a constant current to a preset floating charge voltage threshold, then charged at a constant voltage until the charging current drops to the preset floating charge current threshold, and then the lithium battery is stood and the real-time voltage is recorded; and when the real-time voltage is lower than the preset static voltage value, returning to the previous step to continue the floating charging, and circulating to the first time value, wherein the static voltage value is smaller than the floating charging voltage threshold value. In this embodiment, the first time value is at least 60 days.
In the present embodiment, the constant current charging current is 0.1C, and the floating charge current threshold is 0.01A.
Specifically, in this embodiment, after the step S1 is completed, the lithium battery may be left standing for a period of time, and then the step S2 is performed, so as to further improve the performance of the lithium battery. Specifically, after the voltage of the lithium battery reaches a preset step voltage threshold value, the lithium battery stands still for 10s and then is subjected to floating charging.
And S3, performing constant current discharge on the lithium battery until the preset cut-off voltage is reached. Specifically, the discharge was performed at a constant current of 0.5C in this step.
The invention is further illustrated below with reference to a specific example.
In this embodiment, V1=3.4V, v2=3.45v, v3=3.5V, the float voltage threshold is 3.65V, the static voltage value =3.38V, and the cutoff voltage is equal to 2.0V.
In this embodiment, a lithium iron phosphate 105Ah battery is taken as an example.
Step 1-step charging: charging to 3.4V at a constant current of 63A, charging to 3.45V at a constant current of 52.5A, charging to 3.5V at a constant current of 21A, stopping charging, and standing for 10s;
step 2-floating charge:
(1) Charging to a floating charging voltage of 3.65V at a constant current of 10.5A, keeping the voltage constant until the charging current is reduced to 0.01A, then laying aside, and recording the voltage after laying aside.
(2) And (3) when the BMS voltage detector detects that the static voltage of the battery is less than 3.38V at a certain moment, returning to the previous small step (1), and circulating in sequence to enable the battery to be continuously float-charged.
Step 3-constant current discharge: after 3 months of floating charge circulation, the battery is deeply charged and discharged once.
Step 4, carrying out constant volume on the battery: charging to 3.65V at a constant current of 52.5A, and stopping charging after the constant voltage reaches 5.25A; after standing for 1h and discharging the battery to 2.0V at 52.5A, the discharge capacity was recorded and the capacity retention rate was calculated. If the capacity retention rate is greater than 80%, continuing from step 1 to step 4.
Fig. 3 is a comparison between the battery cycle charge-discharge life curve of the present embodiment and the conventional battery cycle charge-discharge life curve. As shown in the figure, in the present example, the capacity retention rate at the 79 th cycle of the battery charge-discharge cycle is 97.26%, and the capacity retention rate at the 79 th cycle obtained by the conventional battery charge-discharge cycle method is 94.35%. Therefore, the floating charge optimization method provided by the invention can obviously improve the floating charge cycle life of the battery
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention are equivalent to or changed within the technical scope of the present invention.

Claims (1)

1. A lithium iron phosphate battery floating charge optimization method is characterized by comprising the following steps:
step 1: charging to 3.4V at a constant current of 63A, charging to 3.45V at a constant current of 52.5A, charging to 3.5V at a constant current of 21A, stopping charging, and standing for 10s;
step 2: (1) Charging at a constant current of 10.5A until the floating charge voltage is 3.65V, keeping the voltage constant until the charging current is reduced to 0.01A, then laying aside, and recording the voltage after laying aside;
(2) When the BMS voltage detector detects that the static voltage of the battery is less than 3.38V at a certain moment, returning to the previous small step (1), and circulating in sequence to enable the battery to be continuously float-charged;
and step 3: after 3 months of floating charge circulation, carrying out one-time deep charge and discharge on the battery;
and 4, step 4: charging to 3.65V at a constant current of 52.5A, and stopping charging after the constant voltage reaches 5.25A; and standing for 1h, discharging the battery to 2.0V at 52.5A, recording the discharge capacity, calculating the capacity retention rate, and continuing the steps 1 to 4 if the capacity retention rate is greater than 80%.
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CN111817334A (en) * 2020-07-14 2020-10-23 珠海格力电器股份有限公司 Direct-current power supply and distribution control method and system and direct-current micro data center
CN114156957A (en) * 2020-09-07 2022-03-08 北京小米移动软件有限公司 Battery charging method, device and storage medium
CN112180261B (en) * 2020-09-16 2022-04-12 合肥国轩高科动力能源有限公司 Lithium analysis detection method for lithium iron phosphate power battery
CN112510265B (en) * 2020-11-06 2022-11-29 天津力神电池股份有限公司 One-step formation hot-pressing method for improving cycle performance of soft package lithium ion battery
CN113161636B (en) * 2021-02-10 2024-04-30 中国科学院金属研究所 Low-temperature charging technology of lithium iron phosphate battery
CN113178926B (en) * 2021-05-19 2022-07-15 臻懿(北京)科技有限公司 Method and system for controlling balanced charging and discharging of communication base station
CN113219360B (en) * 2021-06-02 2023-09-22 江苏中兴派能电池有限公司 Lithium battery cycle life testing method based on float strategy
CN117872025B (en) * 2024-03-11 2024-06-18 天津普兰能源科技有限公司 Capacitor self-discharge selection method, system and consistency detection method

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US7986129B2 (en) * 2008-01-02 2011-07-26 Cooper Technologies Company Method and system for float charging a battery
CN101615696A (en) * 2009-07-16 2009-12-30 江苏富朗特新能源有限公司 A kind of chemical synthesis technology of flexible packing lithium ion secondary battery
CN104733793A (en) * 2015-04-21 2015-06-24 中投仙能科技（苏州）有限公司 Sectional charging method of lithium ion battery
CN109586367A (en) * 2018-12-03 2019-04-05 浙江大学昆山创新中心 A kind of charging method for ferric phosphate lithium cell

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