CN114833097B - Sorting method and device for gradient utilization of retired power battery - Google Patents

Abstract

The invention discloses a sorting method for the ladder utilization of retired power batteries. The method includes: first screening out batteries with poor appearance and leakage, and then using a voltmeter to screen out batteries that are over-discharged during use; The power battery is charged with constant voltage to the cut-off voltage, and then the current changes of the retired power battery during the constant voltage charging stage are analyzed; the discharge test of the retired power battery is started, and the discharge test process is divided into nine stages. After each stage is completed, the retired power battery is The internal resistance and dynamic process of the screen are screened and analyzed, and retired power batteries that meet the first preset value condition are screened for direct use as a single unit, and those that are not satisfied enter the next stage; for retired power batteries that pass all stages of screening, the consistency meets the first preset value condition. The decommissioned power batteries with two preset value conditions are regrouped and classified into module application scenarios; the advantage of the present invention is that it can screen out decommissioned power batteries that meet the consistency requirements, and the screening efficiency is high.

Description

A sorting method and device for echelon utilization of decommissioned power batteries

Technical field

The present invention relates to the technical field of lithium-ion batteries, and more specifically to a sorting method and device for echelon utilization of decommissioned power batteries.

Background technique

In recent years, the new energy vehicle industry has developed rapidly. As the core component of new energy vehicles, the demand for power batteries has increased dramatically. Generally speaking, a power battery whose battery capacity has declined to 80% is regarded as a "retired power battery". But in the actual recycling process, there are many reasons for battery retirement. The decline in the performance of some modules or batteries will cause the retirement of all battery modules in the vehicle. If these batteries are directly dismantled and scrapped, it will cause a huge waste of resources and aggravate the tight supply of lithium and other resources. These retired power batteries still have high capacity and can be used in energy storage, low-speed electric vehicles and other fields.

However, the classification and processing system in the retired power battery recycling industry is not perfect. Most retired power battery classification companies only use capacity and internal resistance as the basis for judging the health of power batteries. However, under this simple and crude classification system, there are huge safety risks in the use of secondary use equipment. In particular, if multiple retired power batteries with large differences in charge and discharge characteristics are improperly reorganized, the reorganized battery modules are prone to overheating or even directly exploding. Therefore, related research on the classification system of retired power batteries and the consistency of retired power batteries is urgent.

During the echelon utilization process of retired power batteries, retired power batteries used in different echelons have different parameter and performance requirements. The performance and consistency requirements for retired power batteries are low in single-unit utilization scenarios, but the performance and consistency requirements for retired power batteries are higher in regrouping scenarios. Therefore, designing a sorting method for tiered utilization of retired power batteries to meet the needs of different tiered utilization of retired power batteries will help reduce energy consumption, save energy, and help manufacturers save the cost of testing for tiered utilization.

Chinese Patent Publication No. CN111580005A discloses a rapid sorting method and device for echelon-utilized power batteries, which solves the current testing problems of echelon-utilized battery modules that take too long to sort, cost too much, and cannot take into account different battery performance. It measures the open circuit voltage of each of the battery cells, selects the first batch of battery cells that can be used in echelon according to the open circuit voltage, and uses the voltage change value test in the first batch of battery cells that can be used in echelon. The method selects a second batch of battery cells that can be used in a ladder, and sorts them according to the voltage change values of multiple battery cells; and uses different frequency impedances in the second batch of battery cells that can be used in a ladder. The value testing method is used to screen out the third batch of battery cells that can be used in a ladder manner, and the battery cells are sorted according to their impedance values at different frequencies. However, it only sorts out battery cells and cannot select batteries that meet the corresponding application scenarios according to different retired power battery echelon utilization requirements, so the screening efficiency is not high.

Contents of the invention

The technical problem to be solved by this invention is that the prior art sorting method for stepped utilization of decommissioned power batteries cannot select batteries that meet the corresponding application scenarios according to different stepped utilization requirements of decommissioned power batteries, and the screening efficiency is not high.

The present invention solves the above technical problems through the following technical means: a sorting method for ladder utilization of decommissioned power batteries, the method includes:

First, screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use. The screened out batteries are used for disassembly;

Constant voltage charge the retired power battery to the cut-off voltage, then analyze the current changes of the retired power battery during the constant voltage charging stage, and directly disassemble the battery that does not meet the requirements;

Start the discharge test of retired power batteries, and divide the discharge test process into nine stages (0~15% SOC, 15%~25% SOC, 25%~35% SOC, 35%~45% SOC, 45%~55% SOC, 55% ~ 65% SOC, 65% ~ 75% SOC, 75% ~ 85% SOC, 85% ~ 100% SOC are each one stage). Each stage is divided into discharge process, rest process and pulse process. After each stage is completed, the internal resistance and dynamic process of retired power batteries are screened and analyzed, and retired power batteries that meet the first preset value conditions are screened for direct use as a single unit. Those that are not satisfied enter the next stage;

For the retired power batteries that have passed all stages of screening, the retired power batteries whose consistency meets the second preset value condition are regrouped and classified into module application scenarios.

The sorting method of the present invention first screens out the batteries that obviously do not meet the requirements and directly disassembles them through hierarchical screening, and then starts the discharge test on the retired power batteries. The discharge process is divided into nine stages, and the internal resistance and dynamic process of the retired power batteries are analyzed. Conduct screening analysis to select retired power batteries that meet the first preset value condition for direct use alone. Those that do not meet the conditions will enter the next stage. For retired power batteries that have passed all stages of screening, the retired power batteries that meet the first preset value will be retired. The power batteries are regrouped and classified into module applications, which can screen out the outdated batteries among the retired power batteries in a short time, and can screen out the retired power batteries that meet the consistency requirements, and use them according to different echelons of retired power batteries. The requirements are screened for batteries that meet the corresponding application scenarios, and the screening efficiency is high.

Further, the method is to screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use, including:

Screen out batteries with bulges, dents, and traces of electrolyte on the surface for disassembly. Use an electronic scale to screen out retired power batteries that are lower than the normal battery weight for disassembly. Use a voltmeter to measure the voltage below The retired power batteries with a voltage of 0.5V are directly used for disassembly, and the retired power batteries with a voltage between 0.5V and the discharge cut-off voltage are directly used in single use situations.

Further, the current changes of retired power batteries during the constant voltage charging stage are analyzed, and batteries that do not meet the requirements are directly disassembled, including:

Calculate the integral value Q _C of current and time in the constant voltage charging stage, and use retired power batteries whose Q _C value exceeds three times the battery standard Qc value directly for disassembly. The battery standard Qc value refers to the Qc value tested when the battery just leaves the factory. Batteries of the same type and voltage level have the same Qc value when they leave the factory. In practical applications, the battery standard Qc value is preset based on the actual situation.

in,

t ₀ and t ₁ are the starting and ending moments of the constant voltage charging phase of battery charging respectively. Among them, the starting current of the constant voltage charging stage is 1C and the ending current is 1/10C.

Further, the discharge test process is divided into nine stages, each stage is divided into a discharge process, a static process and a pulse process, including: first, charging the retired power battery to the cut-off voltage according to 1C current, and then charging it with 1C current Discharge, calculate the discharge time based on 10% of the rated capacity. After the discharge is completed, let the battery stand for 10 minutes, and record the voltage change of the battery during the standstill period. After standing, the chemical reaction in the battery is stabilized, and then the retired power battery Start the pulse discharge experiment.

Furthermore, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The analysis process includes:

After each discharge, rest, and pulse cycle, the internal resistance and discharge voltage consistency of the sorted retired power batteries are sorted and screened. Batteries that meet the screening conditions enter the next discharge, rest, and pulse cycle. ; Batteries that do not meet the screening conditions will be directly classified into single use situations.

Furthermore, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The parameters analyzed include:

The voltage during the charge and discharge process, the static end voltage, the internal resistance parameters during the pulse process and the voltage parameters after the pulse discharge are completed.

Furthermore, the first preset value condition for selecting retired power batteries that meet the first preset value condition for direct single use is:

The internal resistance is greater than β _R , the voltage at the characteristic moment of charging is greater than β _c , and the voltage at the characteristic moment of discharge is less than β _d , where,

β _R =R _new +0.8*(R _new -R _80% )

β _c =V _new,c +0.8*(V _80%,c -V _new,c )

β _d =V _new,d -0.8*(V _80%,d -V _new,d )

In the formula, R _new represents the calculated internal resistance value of a new battery of the same model, R _80% represents the corresponding resistance value of a retired power battery whose capacity has declined to 80% of the rated capacity of a new battery of the same model, V _{80%, and c} represents a new battery of the same model. The corresponding charging characteristic moment voltage of a retired power battery whose capacity has declined to 80% of the rated capacity. V _new,c represents the calculated charging characteristic moment voltage of a new battery of the same model. V _new,d represents the calculated charging characteristic moment voltage of a new battery of the same model. The discharge characteristic moment voltage, V _{80%, d,} represents the corresponding discharge characteristic moment voltage of a retired power battery of the same model whose capacity has declined to 80% of the rated capacity.

Furthermore, retired power batteries whose consistency meets the second preset value condition are regrouped and classified into module application scenarios, including:

Retired power batteries whose internal resistance is less than α _R , whose charging characteristic moment voltage is less than α _c and whose discharge characteristic moment voltage is greater than α _d are regrouped and classified into module application scenarios, among which,

α _R =R _new +0.2*(R _new -R _80% )

α _c =V _new,c +0.2*(V _80%,c -V _new,c )

α _d =V _new,d -0.2*(V _80%,d -V _new,d ).

The invention also provides a sorting device for ladder utilization of decommissioned power batteries, which device includes:

The preliminary screening module is used to first screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use, and the screened batteries are used for disassembly;

The constant voltage charging screening module is used to constant voltage charge retired power batteries to the cut-off voltage, then analyze the current changes of retired power batteries during the constant voltage charging stage, and directly disassemble batteries that do not meet the requirements;

The hierarchical screening module is used to start the discharge test of retired power batteries. The discharge test process is divided into nine stages. Each stage is divided into a discharge process, a static process and a pulse process. After each stage is completed, the internal content of the retired power battery is evaluated. The resistance and dynamic process are screened and analyzed, and the decommissioned power batteries that meet the first preset value conditions are screened for direct use as a single unit, and those that are not satisfied enter the next stage;

The regrouping module is used to regroup retired power batteries whose consistency meets the second preset value condition for retired power batteries that have passed all stages of screening, and classify them into module application scenarios.

Further, the method is to screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use, including:

Screen out batteries with bulges, dents, and traces of electrolyte on the surface for disassembly. Use an electronic scale to screen out retired power batteries that are lower than the normal battery weight for disassembly. Use a voltmeter to measure the voltage below 0.5 V's retired power batteries are directly used for disassembly, and retired power batteries with a voltage between 0.5V and the discharge cut-off voltage are directly used in single use situations.

Further, the current changes of retired power batteries during the constant voltage charging stage are analyzed, and batteries that do not meet the requirements are directly disassembled, including:

Calculate the integral value Q _C of current and time in the constant voltage charging stage, and use retired power batteries whose Q _C value exceeds three times the battery standard Qc value directly for disassembly.

Further, the discharge test process is divided into nine stages, each stage is divided into a discharge process, a static process and a pulse process, including: first, charging the retired power battery to the cut-off voltage according to 1C current, and then charging it with 1C current Discharge, calculate the discharge time based on 10% of the rated capacity. After the discharge is completed, let the battery stand for 10 minutes, and record the voltage change of the battery during the standstill period. After standing, the chemical reaction in the battery is stabilized, and then the retired power battery Start the pulse discharge experiment.

Furthermore, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The analysis process includes:

After each discharge, rest, and pulse cycle process, the internal resistance and discharge voltage consistency of the sorted retired power batteries are sorted and screened. Batteries that do not meet the first preset value conditions will enter the next discharge, Rest and pulse cycle; batteries that meet the first preset value conditions are directly classified into single use situations.

Furthermore, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The parameters analyzed include:

The voltage during the charge and discharge process, the static end voltage, the internal resistance parameters during the pulse process and the voltage parameters after the pulse discharge are completed.

Furthermore, the first preset value condition for selecting retired power batteries that meet the first preset value condition for direct single use is:

The internal resistance is greater than β _R , the voltage at the characteristic moment of charging is greater than β _c , and the voltage at the characteristic moment of discharge is less than β _d , where,

β _R =R _new +0.8*(R _new -R _80% )

β _c =V _new,c +0.8*(V _80%,c -V _new,c )

β _d =V _new,d -0.8*(V _80%,d -V _new,d )

In the formula, R _new represents the calculated internal resistance value of a new battery of the same model, R _80% represents the corresponding resistance value of a retired power battery whose capacity has declined to 80% of the rated capacity of a new battery of the same model, V _{80%, and c} represents a new battery of the same model. The corresponding charging characteristic moment voltage of a retired power battery whose capacity has declined to 80% of the rated capacity. V _new,c represents the calculated charging characteristic moment voltage of a new battery of the same model. V _new,d represents the calculated charging characteristic moment voltage of a new battery of the same model. The discharge characteristic moment voltage, V _{80%, d,} represents the corresponding discharge characteristic moment voltage of a retired power battery of the same model whose capacity has declined to 80% of the rated capacity.

Furthermore, retired power batteries whose consistency meets the second preset value condition are regrouped and classified into module application scenarios, including:

Retired power batteries whose internal resistance is less than α _R , whose charging characteristic moment voltage is less than α _c and whose discharge characteristic moment voltage is greater than α _d are regrouped and classified into module application scenarios, among which,

α _R =R _new +0.2*(R _new -R _80% )

α _c =V _new,c +0.2*(V _80%,c -V _new,c )

α _d =V _new,d -0.2*(V _80%,d -V _new,d ).

The advantages of the present invention are:

(1) The sorting method of the present invention uses hierarchical screening to first screen out the batteries that obviously do not meet the requirements and directly disassemble them, and then start the discharge test on the retired power batteries. The discharge process is divided into nine stages to evaluate the internal resistance of the retired power batteries. And the dynamic process is conducted for screening analysis, and retired power batteries that meet the first preset value condition are screened for direct use alone. Those that are not satisfied enter the next stage. For retired power batteries that pass all stages of screening, the consistency meets the second preset value. Retired power batteries with value conditions are regrouped and classified into module application scenarios. It can screen out the outdated batteries in the retired power batteries in a short time and screen out the retired power batteries that meet the consistency requirements. According to different retired power batteries, The power battery echelon utilization requirements screen batteries that meet the corresponding application scenarios, and the screening efficiency is high.

(2) The screening method of the present invention maximizes the use of remaining battery energy, helps reduce energy consumption, saves energy, and helps manufacturers save the cost of tiered utilization and detection.

Description of the drawings

Figure 1 is a flow chart of a sorting method for stepped utilization of decommissioned power batteries disclosed in an embodiment of the present invention;

Figure 2 is a schematic diagram of an equivalent circuit model in a sorting method for stepped utilization of decommissioned power batteries disclosed in an embodiment of the present invention;

Figure 3 is a schematic diagram of the change in voltage over time during the discharge test process of a sorting method for stepped utilization of decommissioned power batteries disclosed in an embodiment of the present invention;

Figure 4 is a schematic diagram of changes in current and voltage over time in the pulse process of a sorting method for stepped utilization of decommissioned power batteries disclosed in the embodiment of the present invention;

Figure 5 is a schematic diagram showing the changes of various parameters with capacity in the equivalent circuit model of a sorting method for stepped utilization of decommissioned power batteries disclosed in the embodiment of the present invention. Figure 5(a), Figure 5(b), Figure 5( c) and Figure 5(d) are respectively schematic diagrams of parameter R _1c , parameter R _1d , parameter R _2c , and parameter R _2d changing with capacity;

Figure 6 is a capacity distribution diagram before and after sorting in a sorting method for stepped utilization of retired power batteries disclosed in an embodiment of the present invention; Figure 6(a) is the capacity distribution of retired power batteries before sorting, Figure 6(b) It is the capacity distribution of retired power batteries after passing all stages of screening;

Figure 7 shows the energy conversion efficiency distribution before and after sorting in a sorting method for stepped utilization of retired power batteries disclosed in the embodiment of the present invention; Figure 7(a) shows the energy conversion efficiency distribution of retired power batteries before sorting, Figure 7 (b) is the energy conversion efficiency distribution of retired power batteries after screening at all stages.

Figure 8 shows the average voltage value in the selection process before and after sorting in a sorting method for stepped utilization of retired power batteries disclosed in the embodiment of the present invention; Figure 8(a) shows the average voltage value in the selection process of retired power batteries before sorting , Figure 8(b) shows the average voltage during the selection process of retired power batteries after passing all stages of screening.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the present invention. Examples, not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

Example 1

As shown in Figure 1, a sorting method for stepped utilization of decommissioned power batteries includes:

S1. In the early stage of classification, first screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that have been over-discharged during use. The screened out batteries are used for disassembly; the specific process is:

Screen out batteries with bulges, dents, and traces of electrolyte on the surface for disassembly. Use an electronic scale to screen out retired power batteries that are lower than the normal battery weight for disassembly. Use a voltmeter to measure the voltage below 0.5 V's retired power batteries are directly used for disassembly, and retired power batteries with a voltage between 0.5V and the discharge cut-off voltage are directly used in single use situations.

S2. Constant voltage charge the retired power battery to the cut-off voltage, then analyze the current changes of the retired power battery during the constant voltage charging stage, and directly disassemble the battery that does not meet the requirements; the specific process is:

Calculate the integral value Q _C of current and time in the constant voltage charging stage, and use retired power batteries whose Q _C value exceeds three times the battery standard Qc value directly for disassembly.

S3. Start the discharge test of the retired power battery. Divide the discharge test process into nine stages. Each stage is divided into a discharge process, a static process and a pulse process. After each stage is completed, the internal resistance and dynamic process of the retired power battery will be measured. Conduct screening analysis to select retired power batteries that meet the first preset value conditions for direct use alone, and those that do not meet the conditions will enter the next stage; the specific process is: first, charge the retired power batteries to the cut-off voltage according to 1C current, and then charge them to the cut-off voltage at 1C For current discharge, calculate the discharge time based on 10% of the rated capacity. After the discharge is completed, let the battery stand for 10 minutes and record the voltage change of the battery during the standstill period. After standing, the chemical reaction in the battery is stabilized, and then the decommissioning power is The battery performs pulse discharge experiments.

Among them, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The analysis process includes: after each discharge, rest, and pulse cycle process, the internal resistance and discharge voltage of the sorted retired power battery are A consistent sorting and screening process is performed. Batteries that do not meet the first preset value conditions will enter the next cycle of discharge, rest, and pulse. Batteries that meet the first preset value conditions are directly classified into single use occasions. The parameters analyzed include: voltage during the charge and discharge process, resting end voltage, internal resistance parameters during the pulse process, and voltage parameters after the pulse discharge.

S4. For the retired power batteries that have passed all stages of screening, regroup the retired power batteries whose consistency meets the second preset value condition and classify them into module application scenarios.

The first preset value condition describes the reference value for retired power batteries to be directly used as single cells.

β _R =R _new +0.8*(R _new -R _80% )

β _c =V _new,c +0.8*(V _80%,c -V _new,c )

β _d =V _new,d -0.8*(V _80%,d -V _new,d )

In the formula, β _R , β _c , and β _d describe the calculation methods of internal resistance, charging characteristic moment voltage, and discharge characteristic moment voltage respectively. Among them, the internal resistance of retired power batteries that are directly used as a single unit should be greater than the corresponding β _R , the voltage at the characteristic moment of charging should be greater than the corresponding β _c , and the voltage at the characteristic moment of discharge should be less than the corresponding β _d . R _new represents the calculated internal resistance value of a new battery of the same model, R _80% represents the corresponding resistance value of a retired power battery whose capacity has declined to 80% of the rated capacity of a new battery of the same model, V _{80%, c} represents the decline in capacity of a new battery of the same model The corresponding charging characteristic moment voltage of a retired power battery with a rated capacity of 80%, V _new,c represents the calculated charging characteristic moment voltage of a new battery of the same model, V _new,d represents the calculated discharge characteristic of a new battery of the same model The moment voltage, V _80%,d represents the corresponding discharge characteristic moment voltage of a retired power battery of the same model whose capacity has declined to 80% of its rated capacity. Among them, the charging characteristic moment voltage includes V ₂ and V ₃ in Figure 4, the discharge characteristic moment voltage includes V ₄ , V ₅ , V ₆ , V ₇ , and V ₈ , and the internal resistance includes R _1c , R _1d , R _2d , and R _2c .

Two preset value conditions are set for the sorting of retired power batteries: the second preset value condition describes the reference value that can be used for regrouping.

α _R =R _new +0.2*(R _new -R _80% )

α _c =V _new,c +0.2*(V _80%,c -V _new,c )

α _d =V _new,d -0.2*(V _80%,d -V _new,d )

In the formula, α _R , α _c , and α _d describe the calculation methods of internal resistance, charging characteristic moment voltage, and discharge characteristic moment voltage respectively. Among them, the internal resistance of retired power batteries used for reorganization should be less than the corresponding α _R , the voltage at the characteristic moment of charging should be less than the corresponding α _c , and the voltage at the characteristic moment of discharge should be greater than the corresponding α _d .

The method of the present invention is introduced in detail through specific examples below. As shown in Figure 2, the construction of a lithium-ion battery equivalent circuit model includes: ohmic impedance (ohmic resistance can also be used), charge transfer impedance (charge transfer internal resistance can also be used), Capacitance, equivalent electromotive force.

The SOC status of retired power batteries obtained by recycling is unknown, so there is less information for reference analysis in the charging curve of retired power batteries. During the charging stage, retired power batteries will undergo a constant voltage charging process. As the retired power battery ages, the amount of electricity Qc charged into the retired power battery during the constant voltage charging stage gradually increases. Although the Qc change speed of different batteries with aging is quite different, after the Qc value of a retired power battery exceeds a certain range, it can be considered that the battery has no secondary use value and directly enters the disassembly stage. This sorting mechanism helps eliminate inferior batteries in the early stages of sorting and improves the overall sorting efficiency of retired power batteries.

First, the retired power battery with unknown SOC status is fully charged, and the constant voltage charging stage during the charging process is analyzed. Screen out the batteries with abnormal charging phase and excessively long constant voltage charging phase, and directly disassemble and recover useful material components. Abnormality in the charging stage refers to the current drop rate being much slower than that of a normal battery, that is, the Q _C value exceeds the battery's standard Qc value by three times.

Retired power batteries that meet the screening indicators of the constant voltage charging stage can enter the discharge curve analysis link. During this process, the capacity, dynamic performance, and discharge curve of retired power batteries will be analyzed step by step. Retired power batteries with strong consistency will be used to regroup, batteries with weak consistency but meeting the performance requirements will be used for single unit reuse; retired power batteries that do not meet the performance requirements will directly enter the disassembly process. In order to save time in classifying retired power batteries, capacity, dynamic performance and discharge curve analysis should be concentrated on one discharge process. To this end, the present invention proposes the following discharge process.

In order to analyze the consistency and remaining capacity of retired power batteries, the pulse and discharge processes need to be combined. As shown in Figure 3, retired power batteries need to undergo multiple discharge, rest and pulse processes. During this process, the voltage changes of retired power batteries are recorded. The discharge test process is divided into nine stages, and each stage is divided into discharge process, rest process and pulse process. The discharge process is mainly used for conversion between different SOC stages, and the voltage changes during the discharge process can be used to analyze the consistency of different retired power batteries. The resting process allows the chemical reactions inside the battery to be relieved, preparing for the observation of the dynamic response of the battery during the pulse phase. At the same time, the battery voltage recovery process during the resting process can also be used to analyze the consistency and status of the battery.

As shown in Figure 4, after this process, positive and negative current pulses are applied to the battery respectively. The internal resistance and dynamic process of retired power batteries will be screened and analyzed. As shown in Figure 5, the internal resistance of retired power batteries during the pulse phase can reflect the approximate capacity of the retired power batteries. This is one of the basis for the present invention to use the pulse phase to screen retired power batteries. in,

Figure 6(a) shows the capacity distribution of retired power batteries before sorting, and Figure 6(b) shows the capacity distribution of retired power batteries after passing all stages of screening. It can be seen from the comparison of capacity distribution before sorting in Figure 6 that in addition to screening out retired power batteries with poor performance parameters, the present invention can also screen out retired power batteries with lower capacity. Figure 7(a) shows the energy conversion efficiency distribution of retired power batteries before sorting, and Figure 7(b) shows the energy conversion efficiency distribution of retired power batteries after passing all stages of screening. As can be seen from Figure 7, after all stages of screening, retired power batteries with low charge and discharge energy conversion efficiency (easy to generate heat) were successfully screened out. Figure 8(a) shows the average voltage during the selection process of retired power batteries before sorting, and Figure 8(b) shows the average voltage during the selection process of retired power batteries after passing all stages of screening. Similarly, it can be seen from Figure 8 that retired power batteries after screening at all stages are more consistent.

Taking into account the overall sorting efficiency, when the parameters of a retired power battery at a certain stage are abnormal or inconsistent with most batteries, the retired power battery can be directly discharged at a constant current to the cut-off voltage, and the capacity can be calculated for single unit utilization; when retired When the parameters of a power battery at a certain stage lag behind that of most batteries, that is, the retired power battery meets the first preset value condition, and the retired power battery can be directly used in single utilization situations, thereby improving the overall classification efficiency.

For retired power batteries that have passed all stages of screening, retired power batteries with high consistency and similarity are regrouped for use in module applications.

Through the above technical solutions, the sorting method of the present invention first screens out the batteries that obviously do not meet the requirements and directly disassembles them through hierarchical screening, and then starts the discharge test on the retired power batteries. The discharge process is divided into nine stages. The internal resistance and dynamic process are screened and analyzed, and retired power batteries that meet the first preset value condition are screened for direct use alone. Those that are not satisfied enter the next stage. For retired power batteries that pass all stages of screening, the consistency meets the second Retired power batteries with preset value conditions are regrouped and classified into module application scenarios. The outdated batteries among the retired power batteries can be screened out in a short time. The retired power batteries that meet the consistency requirements can be screened out. According to different According to the retired power battery echelon utilization requirements, batteries that meet the corresponding application scenarios are screened with high screening efficiency.

Example 2

Based on Embodiment 1, the present invention also provides a sorting device for stepped utilization of decommissioned power batteries. The device includes:

The preliminary screening module is used to first screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use, and the screened batteries are used for disassembly;

The constant voltage charging screening module is used to constant voltage charge retired power batteries to the cut-off voltage, then analyze the current changes of retired power batteries during the constant voltage charging stage, and directly disassemble batteries that do not meet the requirements;

The hierarchical screening module is used to start the discharge test of retired power batteries. The discharge test process is divided into nine stages. Each stage is divided into a discharge process, a static process and a pulse process. After each stage is completed, the internal content of the retired power battery is evaluated. The resistance and dynamic process are screened and analyzed, and the decommissioned power batteries that meet the first preset value conditions are screened for direct use as a single unit, and those that are not satisfied enter the next stage;

The regrouping module is used to regroup retired power batteries whose consistency meets the second preset value condition for retired power batteries that have passed all stages of screening, and classify them into module application scenarios.

Specifically, the method is to screen out batteries with poor appearance and leakage, and then use a voltmeter to screen out batteries that are over-discharged during use, including:

Screen out batteries with bulges, dents, and traces of electrolyte on the surface for disassembly. Use an electronic scale to screen out retired power batteries that are lower than the normal battery weight for disassembly. Use a voltmeter to measure the voltage below 0.5 V's retired power batteries are directly used for disassembly, and retired power batteries with a voltage between 0.5V and the discharge cut-off voltage are directly used in single use situations.

Specifically, the current changes of retired power batteries during the constant voltage charging stage are analyzed, and batteries that do not meet the requirements are directly disassembled, including:

Calculate the integral value Q _C of current and time in the constant voltage charging stage, and use retired power batteries whose Q _C value exceeds three times the battery standard Qc value directly for disassembly.

Specifically, the discharge test process is divided into nine stages. Each stage is divided into a discharge process, a static process and a pulse process, including: first, charging the retired power battery to the cut-off voltage according to 1C current, and then charging it with 1C current. Discharge, calculate the discharge time based on 10% of the rated capacity. After the discharge is completed, let the battery stand for 10 minutes, and record the voltage change of the battery during the standstill period. After standing, the chemical reaction in the battery is stabilized, and then the retired power battery Start the pulse discharge experiment.

More specifically, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The analysis process includes:

After each discharge, rest, and pulse cycle, the internal resistance and discharge voltage consistency of the sorted retired power batteries are sorted and screened. Batteries that meet the screening conditions enter the next discharge, rest, and pulse cycle. ; Batteries that do not meet the screening conditions will be directly classified into single use situations.

More specifically, after each stage is completed, the internal resistance and dynamic process of the retired power battery are screened and analyzed. The parameters analyzed include:

The voltage during the charge and discharge process, the static end voltage, the internal resistance parameters during the pulse process and the voltage parameters after the pulse discharge are completed.

The first preset value condition for screening retired power batteries that meet the first preset value condition for direct single use is:

The internal resistance is greater than β _R , the voltage at the characteristic moment of charging is greater than β _c , and the voltage at the characteristic moment of discharge is less than β _d , where,

β _R =R _new +0.8*(R _new -R _80% )

β _c =V _new,c +0.8*(V _80%,c -V _new,c )

β _d =V _new,d -0.8*(V _80%,d -V _new,d )

In the formula, R _new represents the calculated internal resistance value of a new battery of the same model, R _80% represents the corresponding resistance value of a retired power battery whose capacity has declined to 80% of the rated capacity of a new battery of the same model, V _{80%, and c} represents a new battery of the same model. The corresponding charging characteristic moment voltage of a retired power battery whose capacity has declined to 80% of the rated capacity. V _new,c represents the calculated charging characteristic moment voltage of a new battery of the same model. V _new,d represents the calculated charging characteristic moment voltage of a new battery of the same model. The discharge characteristic moment voltage, V _{80%, d,} represents the corresponding discharge characteristic moment voltage of a retired power battery of the same model whose capacity has declined to 80% of the rated capacity.

More specifically, retired power batteries whose consistency meets the second preset value condition are regrouped and classified into module application scenarios, including:

Retired power batteries whose internal resistance is less than α _R , whose charging characteristic moment voltage is less than α _c and whose discharge characteristic moment voltage is greater than α _d are regrouped and classified into module application scenarios, among which,

α _R =R _new +0.2*(R _new -R _80% )

α _c =V _new,c +0.2*(V _80%,c -V _new,c )

α _d =V _new,d -0.2*(V _80%,d -V _new,d ).

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the foregoing embodiments. The recorded technical solutions may be modified, or some of the technical features thereof may be equivalently replaced; however, these modifications or substitutions shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims (8)

1. A method for sorting retired power battery gradient utilization, the method comprising:

firstly screening out batteries with bad appearance and liquid leakage, and then screening out the batteries which are excessively discharged in the using process by utilizing a voltmeter, wherein the screened out batteries are used for disassembly;

constant-voltage charging the retired power battery to cut-off voltage, and then analyzing the current change of the retired power battery in a constant-voltage charging stage, and directly disassembling the battery which does not meet the requirement;

starting discharge test on the retired power battery, dividing the discharge test process into nine stages, wherein each stage is divided into a discharge process, a standing process and a pulse process, screening and analyzing the internal resistance and the dynamic process of the retired power battery when each stage is completed, and screening out direct single use of the retired power battery meeting the condition of a first preset value, and entering the next stage when the internal resistance and the dynamic process of the retired power battery are not met;

for the retired power batteries screened in all stages, the retired power batteries with consistency meeting the second preset value condition are regrouped and classified into module application occasions;

the first preset value condition is as follows:

internal resistance is greater than beta _R The voltage at the charging characteristic moment is larger than beta _c The voltage at the moment of discharge characteristic is less than beta _d Wherein, the method comprises the steps of, wherein,

β _R ＝R _new +0.8*(R _new -R _80％ )

β _c ＝V _new,c +0.8*(V _80％,c -V _new,c )

β _d ＝V _new,d -0.8*(V _80％,d -V _new,d )

wherein R is _new Represents the internal resistance value calculated by a new battery of the same type, R _80％ Representing corresponding resistance value of retired power battery with same model new battery capacity declined to 80% of rated capacity, V _80％,c Representing the voltage at the charging characteristic moment corresponding to the retired power battery with the same model and with the capacity of a new battery declined to 80 percent of rated capacity, V _new,c Representing the calculated charging characteristic moment voltage, V, of a new battery of the same model _new,d Representing the calculated discharge characteristic time voltage of the new battery of the same model, V _80％,d Representing the voltage at the discharge characteristic moment corresponding to the retired power battery with the same model and with the capacity of a new battery declined to 80% of the rated capacity;

the method comprises the steps of grouping retired power batteries with consistency meeting a second preset value condition, classifying the retired power batteries into module application occasions, and comprising the following steps:

satisfy internal resistance less than alpha _R The voltage at the charging characteristic moment is less than alpha _c The voltage at the discharge characteristic moment is greater than alpha _d Is grouped again, classified as a modular application, wherein,

α _R ＝R _new +0.2*(R _new -R _80％ )

α _c ＝V _new,c +0.2*(V _80％,c -V _new,c )

α _d ＝V _new,d -0.2*(V _80％,d -V _new,d )。

2. the method for sorting off-service power cells for cascade utilization according to claim 1, wherein said screening out bad-looking, leaking cells and then screening out overdischarged cells during use with a voltmeter comprises:

the method comprises the steps of screening out batteries with bulges, pits and electrolyte traces on the surfaces, using an electronic scale to screen out retired power batteries with the weight lower than that of normal batteries, using a voltmeter to directly use the retired power batteries with the voltage lower than 0.5V for disassembly, and directly using the retired power batteries with the voltage between 0.5V and discharge cut-off voltage for single use.

3. The method for sorting the cascade utilization of the retired power battery according to claim 1, wherein the analysis of the current change of the retired power battery in the constant voltage charging stage directly disassembles the battery which does not meet the requirement, and the method comprises the following steps:

calculating an integral value Q of current and time in a constant voltage charging stage _C Will Q _C Retired power cells with values three times greater than the standard Qc value of the cell were used directly for disassembly.

4. A sorting method for the cascade utilization of retired power cells according to claim 1, characterized in that the discharge test procedure is divided into nine phases, each of which is divided into a discharge procedure, a rest procedure and a pulse procedure, comprising: firstly, charging the retired power battery to cut-off voltage according to 1C current, discharging with 1C current, calculating discharge time with 10% of rated capacity, standing the battery for 10 minutes after discharge, recording voltage change of the battery during standing, stabilizing chemical reaction in the battery after standing, and then performing pulse discharge experiment on the retired power battery.

5. The method for sorting the cascade utilization of the retired power battery according to claim 4, wherein each time a stage is completed, the internal resistance and the dynamic process of the retired power battery are screened and analyzed, and the analysis process comprises:

each time the discharge, standing and pulse cycle process is carried out, the internal resistance and discharge voltage consistency of the selected retired power battery are separated and screened out once, and the battery which does not meet the first preset value condition enters the next discharge, standing and pulse cycle; the batteries satisfying the first preset value condition are directly classified as single use occasions.

6. The method for sorting the cascade utilization of the retired power battery according to claim 5, wherein each time a stage is completed, the internal resistance and the dynamic process of the retired power battery are screened and analyzed, and the parameters for analysis include:

voltage in the charge and discharge process, standing ending voltage, internal resistance parameter in the pulse process and voltage parameter after the pulse discharge is ended.

7. A sorting apparatus for the echelon utilization of retired power cells, the apparatus comprising:

the primary screening module is used for screening out the batteries with bad appearance and liquid leakage, and then screening out the batteries which are excessively discharged in the use process by utilizing the voltmeter, wherein the screened out batteries are used for disassembly;

the constant voltage charging screening module is used for charging the retired power battery to a cut-off voltage at a constant voltage, and then analyzing the current change of the retired power battery in a constant voltage charging stage, and directly disassembling the battery which does not meet the requirement;

the grading screening module is used for starting discharge test on the retired power battery, dividing the discharge test process into nine stages, dividing each stage into a discharge process, a standing process and a pulse process, screening and analyzing the internal resistance and the dynamic process of the retired power battery when each stage is completed, and screening out direct single use of the retired power battery meeting the first preset value condition and entering the next stage when the internal resistance and the dynamic process of the retired power battery are not met;

the rebuilt module is used for rebuilt the retired power batteries which meet the second preset value condition in consistency for the retired power batteries screened in all stages, and classifying the retired power batteries into module application occasions;

the first preset value condition is as follows:

internal resistance is greater than beta _R The voltage at the charging characteristic moment is larger than beta _c The voltage at the moment of discharge characteristic is less than beta _d Wherein, the method comprises the steps of, wherein,

β _R ＝R _new +0.8*(R _new -R _80％ )

β _c ＝V _new,c +0.8*(V _80％,c -V _new,c )

β _d ＝V _new,d -0.8*(V _80％,d -V _new,d )

wherein R is _new Represents the internal resistance value calculated by a new battery of the same type, R _80％ Representing corresponding resistance value of retired power battery with same model new battery capacity declined to 80% of rated capacity, V _80％,c Representing the voltage at the charging characteristic moment corresponding to the retired power battery with the same model and with the capacity of a new battery declined to 80 percent of rated capacity, V _new,c Representing the calculated charging characteristic moment voltage, V, of a new battery of the same model _new,d Representing the calculated discharge characteristic time voltage of the new battery of the same model, V _80％,d Representing the voltage at the discharge characteristic moment corresponding to the retired power battery with the same model and with the capacity of a new battery declined to 80% of the rated capacity;

the method comprises the steps of grouping retired power batteries with consistency meeting a second preset value condition, classifying the retired power batteries into module application occasions, and comprising the following steps:

satisfy internal resistance less than alpha _R The voltage at the charging characteristic moment is less than alpha _c The voltage at the discharge characteristic moment is greater than alpha _d Is grouped again, classified as a modular application, wherein,

α _R ＝R _new +0.2*(R _new -R _80％ )

α _c ＝V _new,c +0.2*(V _80％,c -V _new,c )

α _d ＝V _new,d -0.2*(V _80％,d -V _new,d )。

8. the sorting apparatus for gradient utilization of retired power cells according to claim 7, wherein the screening out bad looking, leaking cells and then screening out overdischarged cells during use with a voltmeter comprises:

the method comprises the steps of screening out batteries with bulges, pits and electrolyte traces on the surfaces, using an electronic scale to screen out retired power batteries with the weight lower than that of normal batteries, using a voltmeter to directly use the retired power batteries with the voltage lower than 0.5V for disassembly, and directly using the retired power batteries with the voltage between 0.5V and discharge cut-off voltage for single use.