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Sudden capacity failure fault identifying and predetermining method for lithium iron phosphate power battery

A power battery, lithium iron phosphate technology, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., can solve problems such as identification, and achieve the effect of reducing the risk of sudden capacity failure

Inactive Publication Date: 2019-01-04
CHINA AVIATION LITHIUM BATTERY RES INST CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is: the present invention aims at the problem that the "diving" fault of the lithium iron phosphate battery cannot be identified by the external characteristic indicators of the battery (such as conventionally detectable capacity, internal resistance, swelling rate, and self-discharge rate). Invented and proposed an identification and prediction method for "diving" fault identification of lithium iron phosphate power battery

Method used

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  • Sudden capacity failure fault identifying and predetermining method for lithium iron phosphate power battery
  • Sudden capacity failure fault identifying and predetermining method for lithium iron phosphate power battery
  • Sudden capacity failure fault identifying and predetermining method for lithium iron phosphate power battery

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Embodiment 1

[0026] Such as figure 1 As shown, a method for identifying and predicting the "diving" fault of a lithium iron phosphate power battery provided by the present invention includes the following steps:

[0027] Step S1: Carry out a complete standard constant current and constant voltage charging test (CCCV ), constant current charging to 3.65V, constant voltage charging until the end of current 0.02C, and record the charging capacity Q and the corresponding charging terminal voltage V data during the charging process, and get the Q-V curve of the charging process, the sampling and recording period used is 19s.

[0028] In principle, there is a certain difference between constant current and constant voltage charging and constant current charging. Constant current and constant voltage is to switch to constant voltage charging after constant current charging reaches the upper limit of the cut-off voltage until the current drops to approximately 0A. The two methods do not affect th...

Embodiment 2

[0033] Embodiment 2 is a special case of Embodiment 1. The three characteristic peak extreme values ​​in the dQ / dV-SOC curve described in step S3 may appear in some cases in the range of SOC=50% and SOC=80%. The coincidence of characteristic peaks (such as image 3 shown), the model of the battery under test is CA100FI, so the ordinate value corresponding to the dQ / dV curve at SOC=80% in the dQ / dV-SOC curve of the constant capacity charging process after the 700th cycle is approximately taken, as shown in image 3 , namely m*=355Ah / V, K=0.44, but K*=0.227 Figure 4 In the 59# cycle curve shown, the battery dives after the 1000th cycle, which is caused by the loss of active materials and eventually the loss of available active lithium ions. For example, the characteristic peaks corresponding to SOC=80% will disappear after hundreds of cycle decays for batteries with a capacity greater than 100Ah, and the characteristic peaks corresponding to SOC=50% and SOC=80% will be combined ...

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Abstract

The invention provides a sudden capacity failure fault identifying and predetermining method for a lithium iron phosphate power battery. The charging capacity Q and terminal voltage V of the battery in a current-constant charging process are recorded in a preset sampling period to obtain a Q-V curve of the charging process; value differential is carried out on the Q-V curve of the charging processto obtain a dQ / dV-SOC curve; characteristics of the dQ / dV-SOC curve are compared with those of a standard dQ / dV-SOC curve of the battery, and change of characteristic peaks near SOC=50% and SOC=80% in the dQ / dV-SOC curve is analyzed; and LLI information is obtained. The method can be used to reflect internal state of the condition in a lossless way, whether there is a sudden capacity failure fault in the battery and reasons for the fault can be determined visually, 400 times of circulation can be predetermined and identified before sudden capacity failure, and a lithium ion power storage battery of a new energy vehicle is avoided from the risk of sudden capacity failure during operation and utilization after decommissioning.

Description

technical field [0001] The invention relates to a method for diagnosing and predicting the risk of a sudden failure of a lithium-ion power battery capacity of a new energy vehicle, in particular to a method for identifying and predicting a "diving" fault of a lithium iron phosphate power battery, which can be used for when the battery is running and when the car is running. The invention relates to fault prediction during cascade utilization of decommissioned batteries, belonging to the technical field of fault prediction and cascade utilization of lithium-ion power batteries. Background technique [0002] When the lithium iron phosphate battery is in use, there will be a sudden drop in capacity and "diving". Usually, the monitoring of the capacity of this type of battery after production and during operation cannot be identified and diagnosed. There is no symptom of the "diving" battery. Occurrence will cause the energy storage system to be cut off and cannot be used. There...

Claims

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Application Information

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IPC IPC(8): G01R31/36
Inventor 赵艳艳王楠梁梦伟陆猛
Owner CHINA AVIATION LITHIUM BATTERY RES INST CO LTD
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