CN109507600A

CN109507600A - A kind of retired ferric phosphate lithium cell echelon utilizes appraisal procedure

Info

Publication number: CN109507600A
Application number: CN201811552417.3A
Authority: CN
Inventors: 范茂松; 王凯丰; 杨凯; 高飞; 刘皓; 耿萌萌; 张明杰; 王康康
Original assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd; State Grid Shandong Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; China Electric Power Research Institute Co Ltd CEPRI; Electric Power Research Institute of State Grid Shandong Electric Power Co Ltd; State Grid Shandong Electric Power Co Ltd
Priority date: 2018-12-18
Filing date: 2018-12-18
Publication date: 2019-03-22

Abstract

The invention provides a method for evaluating the cascade utilization of retired lithium iron phosphate batteries. The method includes the following steps: removing unqualified retired lithium iron phosphate batteries from historical operation data of lithium iron phosphate power batteries; checking qualified retired lithium iron phosphate batteries The appearance of the battery, screening the lithium iron phosphate power battery that does not meet the standard; evaluating the performance of the retired lithium iron phosphate battery that meets the standard, and determining whether the battery can be used in a cascade; the technical solution provided by the present invention can not only fully grasp the performance of the retired lithium iron phosphate power battery status, and determine whether the battery can be used for cascade utilization, and can also clarify the technical feasibility of the cascade utilization of retired lithium iron phosphate batteries, so as to ensure the safety and electrochemical performance of retired lithium iron phosphate batteries in the process of cascade utilization. The cascade utilization of lithium batteries provides good technical support.

Description

A kind of retired ferric phosphate lithium cell echelon utilizes appraisal procedure

Technical field

The present invention relates to a kind of appraisal procedure of energy storage technology, in particular to a kind of retired ferric phosphate lithium cell echelon benefit Appraisal procedure.

Background technique

With the increase for using the time, the battery performance of the power battery of electric car constantly fails, when battery performance declines After falling back on to a certain degree, in order to ensure the safety in the power performance of electric car, continual mileage and use process, automobile Power battery must be replaced；In general, replaced power battery, high bottom of the residual capacity remained etc., are remained Energy continued to use used in other field, as power battery echelon utilize.

Observation discovery Prospect of EVS Powered with Batteries ferric phosphate lithium ion battery with high security, environmental suitability It is strong and many advantages, such as have extended cycle life, after retired from electric car, it would still be possible to relatively mild for condition, wanted to battery performance Relatively low occasion is sought, to realize that the echelon of retired ferric phosphate lithium ion battery utilizes.

However not all retired ferric phosphate lithium cell can realize that echelon utilizes, because long-term by electric car After use, battery performance obviously fails, those the physical damages such as deformation, leakage have occurred or have crossed the abuse conditions such as charge and discharge Battery there is greatly security risk, unsuitable echelon utilizes；Therefore, realize that the echelon of retired ferric phosphate lithium cell utilizes, than Inferior carry out Performance Evaluation, so that it is guaranteed that safety and chemical property of the retired ferric phosphate lithium cell during echelon utilizes.

The existing echelon for retired ferric phosphate lithium cell utilizes, and appraisal procedure is imperfect, accurate, it is therefore desirable to provide A kind of retired ferric phosphate lithium cell echelon makes retired ferric phosphate lithium cell be fully used using appraisal procedure, and ensures retired Ferric phosphate lithium cell safety during echelon utilizes.

Summary of the invention

In order to meet the needs of the prior art, the present invention provides a kind of retired ferric phosphate lithium cell echelon and utilizes appraisal procedure Determine whether the performance of retired ferric phosphate lithium cell meets the requirement that echelon utilizes, so that it is guaranteed that retired ferric phosphate lithium cell exists Safety and chemical property during echelon utilization.

The purpose of the present invention is what is be achieved through the following technical solutions:

A kind of retired ferric phosphate lithium cell echelon utilizes appraisal procedure, which is characterized in that described method includes following steps:

1) underproof retired ferric phosphate lithium cell is rejected from lithium iron phosphate dynamic battery history data；

2) lithium iron phosphate dynamic battery not up to standard is screened from the appearance of remaining retired ferric phosphate lithium cell；

3) retired ferric phosphate lithium cell performance up to standard is assessed, determines whether battery can be utilized with echelon.

Wherein, the underproof retired ferric phosphate lithium cell of rejecting includes:

(1) once there is the battery of the super 4V of charged voltage；

(2) once there is the battery that voltage after discharging is lower than 2V；Or

(3) running temperature once occurred is more than the battery overheated after 70 DEG C.

Wherein, the appearance screens lithium iron phosphate dynamic battery not up to standard includes: to use visually judge whether battery is up to standard It include: to have breakage, deformation, spot, leakage or mark unintelligible.

Wherein, the assessment retired ferric phosphate lithium cell performance up to standard includes:

Assess open-circuit voltage, internal resistance, capacity, storage, environmental suitability, rate charge-discharge or heat generation characteristic.

Wherein, the Performance Evaluation of the open-circuit voltage includes: open-circuit voltage U < 2V or U the > 4V for detecting the battery, then The battery is undesirable.

Wherein, the Performance Evaluation of the internal resistance includes: internal resistance of the measurement battery under 20-100%SOC state-of-charge 2 times of internal resistance value, determine whether the battery meets the requirements when whether resistance value is greater than battery factory.

Wherein, the Performance Evaluation of the capacity includes:

With multiplying power X to the cycle charge-discharge under the battery room temperature, and record the discharge capacity C of each charge and discharge₀；

Discharge capacity C after calculating the battery n-th circulation₀With rated capacity P₀Ratio, if C₀/P₀< 0.7, then

The battery is undesirable.

The Performance Evaluation of the storage includes:

Battery is charged to after saturation state with the multiplying power X and is placed 28-30 days under room temperature；

Battery after placing 28-30 days is subjected to the cycle charge-discharge to battery with the multiplying power X again, records battery the 1 discharge capacity C₁With the cyclic discharge capacity C of n-th_N；

According to the C₁、C_NAnd C₀Calculate battery capacity retention ratio whether be lower than 92% or capacity restoration rate whether be lower than Lower than 95%, determine whether the battery meets the requirements；

The capacity retention ratio presses C₁/C₀× 100% calculates；

The capacity restoration rate presses C_N/C₀× 100% calculates.

Wherein, the performance estimating method of the environmental suitability includes:

Measure the charge and discharge for carrying out 100%DOD charge and discharge to battery with multiplying power Y under at least tri- different temperatures of a, b and d Capacity；

Calculate separately the ratio C of the charge/discharge capacity at a temperature of charge/discharge capacity and b of the battery at a temperature of a and d_a/C_b And C_d/C_b；According to the C_a/C_bWhether < 0.90 or C_d/C_bWhether < 0.95, determine whether the battery meets the requirements.

Wherein, in the temperature, 0≤a < b < d, b are room temperature.

Wherein, the performance estimating method of the multiplying power includes:

1) under room temperature, charge and discharge is carried out to a battery with multiplying power X, Y and Z, are recorded under X, Y and Z multiplying power respectively Charge/discharge capacity Cx, Cy and Cz of the battery；

2) the ratio C y/Cx and Cz/Cx of the Cy and Cz and Cx are calculated separately；According to the Cy/Cx of calculating whether < 0.98 Or Cz/Cx whether < 0.95, determine whether the battery meets the requirements.

Wherein, the multiplying power X < Y < Z.

Wherein, the performance estimating method of the heat generation characteristic includes:

1) thermocouple is set in battery surface, record battery is carrying out the temperature in charge and discharge process with the multiplying power Y and Z T_YAnd T_Z；

2) by the temperature T_YAnd T_ZWith environment temperature T₀Comparison, if according to T_Y-T₀5 DEG C of > or T_Z-T₀Whether 10 DEG C of >, Determine whether the battery meets the requirements.

Compared with the immediate prior art, technical solution of the present invention is had the following beneficial effects:

Retired ferric phosphate lithium cell echelon provided by the invention utilizes appraisal procedure, using analysis lithium iron phosphate dynamic battery History data, reject underproof retired ferric phosphate lithium cell, passed examination retired ferric phosphate lithium cell appearance, sieve It selects lithium iron phosphate dynamic battery not up to standard and assesses retired ferric phosphate lithium cell performance up to standard, determine whether battery can ladder Whether the secondary technical solution utilized, has not only grasped the performance condition of retired lithium iron phosphate dynamic battery comprehensively, but also can be with for battery Echelon is obtained using technical support, safety and chemical property of the retired ferric phosphate lithium cell during echelon utilizes is provided To reliably ensure that, good technical support is provided for the echelon utilization of retired ferric phosphate lithium cell.

Detailed description of the invention

Fig. 1 is the flow diagram of appraisal procedure of the present invention；

Fig. 2 is the line chart of the openning circuit voltage detection result of 48 batteries described in the embodiment of the present invention,

Fig. 3 is the line chart of the internal resistance detection result of 48 batteries described in the embodiment of the present invention；

Fig. 4 is the line chart of discharge capacity of the cell testing result described in the embodiment of the present invention；

Fig. 5 is the cake chart of battery storage performance test results described in the embodiment of the present invention；

The temperature profile of battery when Fig. 6 is charge and discharge under different multiplying of the embodiment of the present invention (1/3C, 1/2C and 1C), (a) temperature profile to charge with the multiplying power is represented, (b) is represented with the temperature profile of the multiplying power discharging.

Specific embodiment

Below by specific embodiments and the drawings, further details of the technical solution of the present invention:

As shown in Figure 1, a kind of retired ferric phosphate lithium cell echelon utilizes appraisal procedure, described method includes following steps:

1) lithium iron phosphate dynamic battery history data is analyzed, underproof retired ferric phosphate lithium cell is rejected；

2) with the appearance of the retired ferric phosphate lithium cell of ocular estimate passed examination, it is dynamic to screen appearance LiFePO4 not up to standard Power battery；

The history data includes voltage and temperature data；The judgment criteria of the defect of data includes:

(1) once there is the battery of the super 4V of charged voltage in battery；

(2) once there is battery of the voltage lower than 2V after electric discharge in battery；Or

(3) it is more than the battery overheated after 70 DEG C that running temperature, which once occurred, in battery.

Appearance battery not up to standard includes: that battery has breakage, deformation, spot, leakage, dry tack free and/or mark Know unintelligible.

The method of the determination successively includes open-circuit voltage, internal resistance, capacity, storage, environmental suitability, rate charge-discharge It is assessed item by item with the battery performance of heat generation characteristic, if one of them are undesirable, excludes a possibility that echelon utilizes.

The Performance Evaluation of the open-circuit voltage includes: the open-circuit voltage U for detecting the battery, if U < 2V or U > 4V, The battery is undesirable.

The Performance Evaluation of the internal resistance includes: the internal resistance resistance value that the battery is measured under 20-100SOC state-of-charge, if The internal resistance resistance value is greater than 2 times of the factory internal resistance value of the battery, then the battery is undesirable.

The Performance Evaluation of the capacity includes:

1) under room temperature, the discharge capacity C of n-th to the battery charging and discharging n times and is recorded with multiplying power X₀；

2) the discharge capacity C of the battery n-th is calculated₀With rated capacity P₀Ratio, if C₀/P₀< 0.7, then it is described Battery is undesirable.

The Performance Evaluation of the storage includes:

1) battery is charged to after saturation state with the multiplying power X and is placed M days under room temperature；

2) battery of placement M days carries out battery with the multiplying power X to the charge and discharge of the n times, record battery the 1st time Discharge capacity C₁With the discharge capacity C of n-th_N；

3) according to the C₁、C_NAnd C₀Calculate the capacity retention ratio and capacity restoration rate of battery；If capacity retention ratio is lower than 92% or capacity restoration rate be lower than 95%, then the battery is undesirable；

The formula of the calculating is respectively as follows:

Capacity retention ratio: C₁/C₀× 100%；

Capacity restoration rate: C_N/C₀× 100%.

The performance estimating method of the environmental suitability includes:

1) 100%DOD charge and discharge are carried out to battery with multiplying power Y, measures the battery in tri- kinds of temperature a, b and d not equality of temperature Charge/discharge capacity under degree；0≤a of temperature < b < d, b are room temperature.

2) ratio C of the charge/discharge capacity at a temperature of charge/discharge capacity and b of the battery at a temperature of a and d is calculated separately_a/C_b And C_d/C_b；If the C_a/C_b< 0.90 or C_d/C_b< 0.95, then the battery is undesirable.

The performance estimating method of the multiplying power includes:

1) under room temperature, charge and discharge is carried out to battery with multiplying power X, Y and Z, record filling under X, Y and Z multiplying power respectively Discharge capacity Cx, Cy and Cz；The multiplying power x < y < z.

2) the ratio C y/Cx and Cz/Cx of the Cy and Cz and Cx are calculated separately；If Cy/Cx < 0.98 or Cz/Cx < 0.95, then the battery is undesirable.

The performance estimating method of the heat generation characteristic includes:

1) thermocouple is set in battery surface, record battery is corresponding in the multiplying power Y and Z progress charge and discharge process Temperature T_YAnd T_Z；

2) by the temperature T_YAnd T_ZWith environment temperature T₀Comparison, if T_Y-T₀5 DEG C of > or T_Z-T₀10 DEG C of >, then the battery It is undesirable.

Below by taking the retired lithium iron phosphate dynamic battery to get off of 48 electric charging stations as an example and in conjunction with chart, the present invention is mentioned The technical solution of confession is described in further details, and the battery factory parameter includes: direction flexible package ferric phosphate lithium cell, specified Capacity: 25Ah, nominal voltage: 3.20V, charge cutoff voltage: 3.65V, discharge cut-off voltage: 2.20V, internal resistance≤2.0m Ω.

1) 48 lithium iron phosphate dynamic battery history datas are analyzed, underproof retired LiFePO4 electricity is rejected Pond:

By the background monitoring platform of electric charging station, the voltage of this 48 batteries and the history data of temperature are transferred, It is analyzed, it is found that after this 48 batteries do not occur overcharge during history run that voltage is lower than 2V after the super 4V of voltage, electric discharge Or running temperature is more than the case where overheat after 70 DEG C.

2) with the appearance for visually inspecting this 48 qualified retired ferric phosphate lithium cells, it is dynamic to screen LiFePO4 not up to standard Power battery:

Under the conditions of light is good, the appearance of 48 batteries is checked, these batteries are without breakage, without change Shape, without spot, without leakage, and battery surface is dry, mark is clear correct.

3) to 48 retired ferric phosphate lithium cells up to standard open-circuit voltage, internal resistance, capacity, storage, environmental suitability, times The battery performance parameter of rate charge and discharge and heat generation characteristic is assessed item by item, if one of them are undesirable, excludes echelon utilization A possibility that.

The Performance Evaluation of the open-circuit voltage includes: to be opened using high-accuracy voltage table retired ferric phosphate lithium cell monomer Road voltage is detected, Fig. 2 be 48 batteries openning circuit voltage detection as a result, the open-circuit voltage of all batteries all in 2-4V Within, belong to normal open-circuit voltage, meets the requirement that echelon utilizes.

The Performance Evaluation of the internal resistance includes: the internal resistance resistance value that the battery is measured under 20-100SOC state-of-charge, figure 3 be the internal resistance detection of 48 batteries as a result, wherein having the internal resistance (4.25m Ω) of 1 battery has been more than 2 times of initial internal resistance (4m Ω) gives up echelon utilization to it.

The Performance Evaluation of the capacity includes:

1) under room temperature, the 3rd discharge capacity C to remaining power charge and discharge 3 times and is recorded with 1/3C multiplying power₀, It is as shown in Figure 4 to record result；

2) battery the 3rd time discharge capacity C is calculated₀With rated capacity P₀The ratio of=25Ah, wherein there is 1 battery Capacity (15.4Ah) be lower than nominal capacity (25Ah) 70%, it is given up echelon utilization.

The Performance Evaluation of the storage includes:

1) remaining power is charged to after saturation state with the 1/3C multiplying power and is placed 7 days under room temperature；

2) battery for placing 7 days is subjected to 3 charge and discharge to battery with 1/3C multiplying power, the electric discharge that record is battery the 1st time is held Measure C₁With the 3rd discharge capacity C₃；

3) according to the C₁、C₃And C₀Calculate the capacity retention ratio and capacity restoration rate of battery；The formula of the calculating is distinguished Are as follows:

Capacity retention ratio: C₁/C₀× 100%；

Capacity restoration rate: C₃/C₀× 100%；

Fig. 5 is the calculated result of the storge quality of battery, and as can be seen from the figure the capacity retention ratio of all batteries is high In 92%, capacity restoration rate is above 95%, so meeting the requirement that gradient utilizes.

The performance estimating method of the environmental suitability includes:

1) with 1/2C multiplying power to the battery carry out 100%DOD constant current charge-discharge, measure the battery in 0 DEG C, 25 DEG C and Charge/discharge capacity at 55 DEG C, the results are shown in Table 1 for record；

2) battery is calculated separately in 0 DEG C and the ratio of 55 DEG C of charge/discharge capacity and 25 DEG C of charge/discharge capacity；Calculate knot It is as shown in the table for fruit:

Table 1

As can be drawn from Table 1: battery charge/discharge capacity ratio at 55 DEG C of charge/discharge capacities and 25 DEG C is higher than 0.95, in 0 Charge/discharge capacity ratio is higher than 0.90 at DEG C charge/discharge capacity and 25 DEG C, meets gradient using requiring.

The performance estimating method of the multiplying power includes:

1) under room temperature, with multiplying power 1/3C, 1/2C and 1C to battery charging and discharging, 1/3C, 1/2C and 1C multiplying power are recorded respectively Under charge/discharge capacity C_1/3c、C_1/2cAnd C_1c, as shown in table 2 below；

2) ratio calculated C_1/2c/C_1/3cAnd C_1c/C_1/3cAs shown in table 2 below；

Multiplying power	1/3C	1/2C	1C
				Charging capacity (Ah)	18.50	18.41	18.05
Volume percent (%)	100.0%	99.5%	97.6%
				Discharge capacity (Ah)	18.64	18.60	18.54
Volume percent (%)	100.0%	99.8%	99.5%

Table 2

As can be drawn from Table 2: battery ratio of charge/discharge capacity and 1/3C rate charge-discharge capacity under 1/2C multiplying power is high The ratio of charge/discharge capacity and 1/3C rate charge-discharge capacity is higher than 0.95 in 0.98, under 1C multiplying power, meets what gradient utilized It is required that.

1) thermocouple is set in battery surface, record battery carries out in charge and discharge process under with 1/2C multiplying power and 1C multiplying power Temperature T_1/2cAnd T_1c；

2) by the temperature T_1/2cAnd T_1cWith environment temperature T₀Comparison, comparing result is as shown in fig. 6, analyze it is found that battery The temperature difference of temperature and environment temperature during 1/2C rate charge-discharge is less than the temperature during 5 DEG C, 1C rate charge-discharge The temperature difference with environment temperature meets the requirement that gradient utilizes less than 10 DEG C.

The above embodiments are merely illustrative of the technical scheme of the present invention and are not intended to be limiting thereof, although referring to above-described embodiment pair The present invention is described in detail, those of ordinary skill in the art still can to a specific embodiment of the invention into Row modification perhaps equivalent replacement these without departing from any modification of spirit and scope of the invention or equivalent replacement, applying Within pending claims of the invention.

Claims

1. a decommissioned lithium iron phosphate battery echelon utilization evaluation method, is characterized in that, described method comprises the steps:

1) Eliminate unqualified decommissioned lithium iron phosphate batteries from the historical operation data of lithium iron phosphate power batteries;

2) Screen the lithium iron phosphate power batteries that do not meet the standard from the appearance of the remaining retired lithium iron phosphate batteries;

3) Evaluate the performance of decommissioned lithium iron phosphate batteries that meet the standards to determine whether the batteries can be used in cascade.

2. a kind of decommissioned lithium iron phosphate battery cascade utilization evaluation method as claimed in claim 1 is characterized in that, described rejecting unqualified decommissioned lithium iron phosphate battery comprises:

(1) There has been a battery with a voltage exceeding 4V after charging;

(2) There has been a battery with a voltage lower than 2V after discharge; or

(3) There have been cases where the battery overheated after the operating temperature exceeded 70°C.

3. a kind of decommissioned lithium iron phosphate battery cascade utilization evaluation method as claimed in claim 1, is characterized in that, the lithium iron phosphate power battery that described appearance screening is not up to standard comprises: Judging whether battery is up to standard with visual inspection comprises: there is damage , deformation, stains, leakage or unclear identification.

4. a kind of decommissioned lithium iron phosphate battery cascade utilization evaluation method as claimed in claim 1, is characterized in that, described evaluation standard decommissioned lithium iron phosphate battery performance comprises:

Evaluate open circuit voltage, internal resistance, capacity, storage, environmental suitability, rate charge-discharge or heat generation characteristics.

5. The method for evaluating the cascade utilization of a retired lithium iron phosphate battery according to claim 4, wherein the performance evaluation of the open circuit voltage comprises: detecting the open circuit voltage of the battery U<2V or U>4V, then The battery does not meet the requirements.

6 . The method for evaluating the cascade utilization of a retired lithium iron phosphate battery according to claim 4 , wherein the performance evaluation of the internal resistance comprises: measuring the internal resistance of the battery in a state of charge of 20-100% SOC. 7 . Whether the resistance value is greater than 2 times the internal resistance value of the battery when it leaves the factory, determine whether the battery meets the requirements.

7. The method for evaluating the cascade utilization of a decommissioned lithium iron phosphate battery according to claim 4, wherein the performance evaluation of the capacity comprises:

1) Cycle charge and discharge of the battery at room temperature with a rate X, and record the discharge capacity C ₀ of each charge and discharge;

2) Calculate the ratio of the discharge capacity C ₀ to the rated capacity P ₀ of the battery after the Nth cycle. If C ₀ /P ₀ <0.7, the battery does not meet the requirements.

8. A decommissioned lithium iron phosphate battery echelon utilization evaluation method as claimed in claim 7, is characterized in that, the performance evaluation of described storage comprises:

Charge the battery to a saturated state at the stated rate X and place it at room temperature for 28-30 days;

The battery after being placed for 28-30 days is then charged and discharged in the cycle at the stated rate X, and the first discharge capacity C ₁ and the Nth cycle discharge capacity C _N of the battery are recorded;

3) Calculate whether the capacity retention rate of the battery is lower than 92% or whether the capacity recovery rate is lower than 95% according to the C ₁ , _CN and C ₀ to determine whether the battery meets the requirements;

The capacity retention rate is calculated according to C ₁ /C ₀ ×100%;

The capacity recovery rate is calculated as _CN /C ₀ ×100%.

9. The method for evaluating the cascade utilization of a decommissioned lithium iron phosphate battery according to claim 8, wherein the performance evaluation method for the environmental adaptability comprises:

1) Determining the charge-discharge capacity of the battery for 100% DOD charge-discharge at the rate Y at at least three different temperatures a, b and d;

2) Calculate the ratios C _a /C _b and C _d /C _b of the charge-discharge capacity of the battery at temperatures a and d to the charge-discharge capacity at temperature b respectively; according to whether the C _a /C _b is less than 0.90 or Whether C _d /C _b is less than 0.95, determine whether the battery meets the requirements.

10 . The method for evaluating the cascade utilization of decommissioned lithium iron phosphate batteries according to claim 9 , wherein, in the temperature, 0≦a<b<d, and b is normal temperature. 11 .

11. The method for evaluating the cascade utilization of decommissioned lithium iron phosphate batteries as claimed in claim 9, wherein the method for evaluating the performance of the rate comprises:

1) Under normal temperature, charge and discharge a battery with the stated rates X, Y and Z, and record the charge and discharge capacities Cx, Cy and Cz of the battery under the X, Y and Z rates respectively;

2) Calculate the ratios Cy/Cx and Cz/Cx of Cy and Cz to Cx respectively; determine whether the battery meets the requirements according to whether the calculated Cy/Cx is less than 0.98 or whether Cz/Cx is less than 0.95.

12 . The method for evaluating the cascade utilization of decommissioned lithium iron phosphate batteries according to claim 9 , wherein the magnification is X<Y<Z. 13 .

13. The method for evaluating the cascade utilization of decommissioned lithium iron phosphate batteries according to claim 9, wherein the method for evaluating the performance of the heating characteristics comprises:

1) A thermocouple is set on the surface of the battery, and the temperature T _Y and T _Z of the battery in the process of charging and discharging at the stated rates Y and Z are recorded;

2) Compare the temperatures TY and TZ with the ambient temperature T0, and determine whether the battery meets the requirements according to whether TY-T0>5°C or whether TZ-T0>10°C.