Summary of the invention
Determine inaccurate problem in order to solve lithium-ion-power cell maximum charge and discharging current in prior art, the embodiment of the present invention provides a kind of lithium-ion-power cell the maximum definite method that uses electric current.Described technical scheme is as follows:
The embodiment of the present invention provides a kind of lithium-ion-power cell the maximum definite method that uses electric current, and described method comprises:
Adopt the electric current of 1/3 size of the rated capacity of lithium-ion-power cell to be measured to described lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h;
Measure the terminal voltage of described lithium-ion-power cell and the terminal voltage of testing equipment;
Adopt the electric current of nominal capacity size 1C that described lithium-ion-power cell is discharged into final discharging voltage, shelve 3~5min, adopt the current charges 12min of described nominal capacity size 1C, shelve 3~5min, adopt respectively 0.5C*n current discharge, to be 12S discharge time, the discharge voltage recording be electric discharge when voltage is set corresponding electric current be defined as maximum discharge current I
dis-max1it is the difference Δ V that final discharging voltage value deducts the terminal voltage of described lithium-ion-power cell and the terminal voltage of described testing equipment that described electric discharge arranges voltage, wherein, n ∈ [1,40] and be positive integer, described nominal capacity size 1C adopts the electric current of 1/3 size of described lithium-ion-power cell rated capacity to the last discharge capacity in described lithium-ion-power cell charge and discharge cycles 2~3 times;
1/3 the electric current that adopts nominal capacity size 1C is to described lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h;
Adopt the electric current of described nominal capacity size 1C to charge to charging upper limit voltage to described lithium-ion-power cell, shelve 3~5min, adopt the current discharge 18min of described nominal capacity size 1C, shelve 3~5min, adopt respectively 0.5C*m current charges, to the charging interval be 12S, the charging voltage recording be charging when voltage is set corresponding electric current be defined as maximum charging current I
charge-max1, it is the difference Δ V that charging upper limit voltage adds the terminal voltage of the above lithium-ion-power cell and the terminal voltage of described testing equipment that described charging arranges voltage, wherein, and m ∈ [Isosorbide-5-Nitrae 0] and be positive integer.
Alternatively, described method also comprises: measuring when discharge time is 12S, discharge voltage is the Positive Poles of described lithium-ion-power cell and the temperature in centre position of described electric discharge when voltage is set, be greater than when meeting difference DELTA T1>=25 ℃, the described Positive Poles temperature of temperature in described Positive Poles and described centre position that 50 ℃, the temperature in described centre position are greater than any in 50 ℃ or when multiple, described maximum discharge current is defined as I
dis-max, and I
dis-max=I
dis-max1-0.1C*a, wherein, a is 1,2,3.
Alternatively, described method also comprises: measuring when the charging interval is 12S, charging voltage is the described Positive Poles of described charging when voltage is set and the temperature in described centre position, be greater than when meeting the temperature of difference DELTA T2>=20 ℃, described Positive Poles of temperature in described Positive Poles and described centre position that 45 ℃, the temperature in described centre position are greater than any in 45 ℃ or when multiple, described maximum charging current is defined as I
charge-max, and I
charge-max=I
charge-max1-0.1C*b, wherein, b is 1,2,3.
1/2 1/2 the position that adds the above Positive Poles height of the housing height that preferably, described centre position is described lithium-ion-power cell.
Alternatively, shelve 1~2h again after cycling completes and is full of electricity after, described method also comprises:
Whether the variation of observing in the terminal voltage 30min of described lithium-ion-power cell is 0.
Preferably, the temperature of the test environment of described lithium-ion-power cell is 24.5~25.5 ℃.
Further, described method also comprises:
Described lithium-ion-power cell is shelved to 4~5h in the temperature of described test environment.
Alternatively, described lithium-ion-power cell is the one in the method for soft package lithium ion power of metal, plastics duricrust, aluminum-plastic composite membrane.
Preferably, described maximum discharge current I
dis-maxwith I
dis-max1, described maximum charging current I
charge-maxwith I
charge-max1be integer, and meet fractional part>=0.8 o'clock carry, when fractional part <0.8, cast out.
Alternatively, described method also comprises:
Utilize test lead, the both positive and negative polarity of described lithium-ion-power cell is connected with the both positive and negative polarity of described testing equipment respectively, the resistance of described test lead is less than or equal to 10m Ω.
The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is:
By under the low SOC state of lithium-ion-power cell, it is carried out to charging and discharging, do not damaging under the prerequisite of battery electrical property, by determining repeatedly in charge and discharge process, the time of discharging and recharging is 12S, and electric current when discharge voltage and charging voltage reach respectively final discharging voltage and charging upper limit voltage, accurately calculate maximum discharge current and maximum charging current that battery can bear, convenient, fast, data processing is simple, easily grasp, effectively avoid overcharging and overdischarge phenomenon of lithium-ion-power cell, guarantee the useful life of battery, reduce the cost of new-energy automobile, and be conducive to its popularization.In addition, maximum charge and discharging current can provide strong reference for the charging and discharging currents of the needs of lithium-ion-power cell reality accurately, and then solve its charging and discharging currents and select variety of issue unreasonable and that bring.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
Embodiment mono-
The embodiment of the present invention provides the maximum electric current that uses of a kind of lithium-ion-power cell to determine method, and referring to Fig. 1, method comprises:
Step 101: adopt the electric current of 1/3 size of the rated capacity of lithium-ion-power cell to be measured to lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h.
Step 102: measure the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment.
Step 103: adopt the electric current of nominal capacity size 1C that lithium-ion-power cell is discharged into final discharging voltage, shelve 3~5min, adopt the current charges 12min of nominal capacity size 1C, shelve 3~5min, adopt respectively 0.5C*n current discharge, to be 12S discharge time, the discharge voltage recording be electric discharge when voltage is set corresponding electric current be defined as maximum discharge current I
dis-max1it is the difference Δ V that final discharging voltage value deducts the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment that electric discharge arranges voltage, wherein, n ∈ [1,40] and be positive integer, nominal capacity size 1C adopts the electric current of 1/3 size of lithium-ion-power cell rated capacity to the last discharge capacity in lithium-ion-power cell charge and discharge cycles 2~3 times.
Step 104: 1/3 the electric current that adopts nominal capacity size 1C is to lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h.
Step 105: adopt the electric current of nominal capacity size 1C to charge to charging upper limit voltage to lithium-ion-power cell, shelve 3~5min, adopt the electric current of nominal capacity size 1C to battery discharge 18min to be measured, shelve 3~5min, adopt respectively 0.5C*m current charges, to the charging interval be 12S, the charging voltage recording be charging when voltage is set corresponding electric current be defined as maximum charging current I
charge-max1, voltage is set is the difference Δ V that charging upper limit voltage adds the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment in charging, wherein, and m ∈ [Isosorbide-5-Nitrae 0] and be positive integer.
Wherein, the maximum electric current that uses comprises maximum discharge current and maximum charging current, final discharging voltage and charging upper limit voltage provide by battery production producer, and the final discharging voltage of lithium-ion-power cell is 2.5V~2.7V conventionally, and charging upper limit voltage is 3.7V~4.2V.
The embodiment of the present invention is by under the low SOC state of lithium-ion-power cell, it is carried out to charging and discharging, do not damaging under the prerequisite of battery electrical property, by determining repeatedly in charge and discharge process, the time of discharging and recharging is 12S, and electric current when discharge voltage and charging voltage reach respectively final discharging voltage and charging upper limit voltage, accurately calculate maximum discharge current and maximum charging current that battery can bear, convenient, fast, data processing is simple, easily grasp, effectively avoid overcharging and overdischarge phenomenon of lithium-ion-power cell, guarantee the useful life of battery, reduce the cost of new-energy automobile, and be conducive to its popularization.In addition, maximum charge and discharging current can provide strong reference for the charging and discharging currents of the needs of lithium-ion-power cell reality accurately, and then solve its charging and discharging currents and select variety of issue unreasonable and that bring.
Embodiment bis-
The embodiment of the present invention provides the maximum electric current that uses of a kind of lithium-ion-power cell to determine method, and referring to Fig. 2, the method comprises:
Step 201: utilize test lead, the both positive and negative polarity of lithium-ion-power cell is connected with the both positive and negative polarity of testing equipment respectively, and guarantee firmly.
Wherein, testing equipment is that high-precision alternating current is converted to galvanic lithium ion battery testing equipment.In the present embodiment, the electric current resolution 0.0001A of testing equipment, voltage resolution is 0.0001V, data record resolution is 0.001S, and the maximum range electric current of testing equipment is 15~20 times of lithium-ion-power cell actual discharge capacity.
When specific implementation, also need the resistance of test lead to be less than or equal to 10m Ω, need to measure the internal resistance that contacts that contacts internal resistance and negative pole and measure traverse line of lithium ion power battery cathode and measure traverse line, guarantee aforementioned both all in controlled range, guarantee the accuracy of result to reduce error.It should be noted that, the concrete control range of contact internal resistance also may be different because of the difference of testing equipment, battery pole ear etc.
It should be noted that, can adopt torque spanner, make to reach lithium-ion-power cell and being connected of testing equipment torque value and guarantee the firm of connection.
In the present embodiment, lithium-ion-power cell is the one in the method for soft package lithium ion power of metal, plastics duricrust, aluminum-plastic composite membrane.
Step 202: lithium-ion-power cell is shelved to 4~5h in the temperature of test environment.
Preferably, the temperature of the test environment of lithium-ion-power cell is 24.5~25.5 ℃.Open ambient temperature control power supply, and the temperature of adjusting ambient, in the time monitoring temperature and be 25 ℃, lithium-ion-power cell is shelved to wherein 4~5h, at room temperature shelve the sufficiently long time, make the inside and outside ambient temperature of lithium-ion-power cell reach basically identical, and stable.
Step 203: adopt the electric current of 1/3 size of the rated capacity of lithium-ion-power cell to lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h.
Lithium-ion-power cell is first carried out to the charge-discharge test of 2~3 times, to guarantee that lithium-ion-power cell to be measured can complete stable discharging and recharging.Cycling complete and be full of electricity after again lithium-ion-power cell is shelved to 1~2h, to guarantee that electric current, voltage etc. after battery to be measured charging have reached stable state.
The method can also comprise: whether the variation in the voltage 30min of observation lithium-ion-power cell is 0.This step is carried out after step 203.When observe in 30min change in voltage time, can continue to extend observing time, conventionally long enough of 30min, lithium-ion-power cell to be measured is stable, voltage no longer changes; In the time observing voltage and no longer change, can proceed next step.By observing the situation of change of voltage of lithium-ion-power cell to be measured, further guarantee that lithium-ion-power cell to be measured has reached stable state, and then guarantee the accuracy of test result.
Step 204: measure the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment.
Particularly, can adopt universal instrument (for example, five half universal instruments) to measure the terminal voltage of lithium-ion-power cell to be measured and the terminal voltage of testing equipment.
While realization, after step 204, the method can also comprise: calculate the difference Δ V of the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment, to facilitate subsequent step to use.Δ V essence is the voltage loss of test lead.
Step 205: adopt the electric current of nominal capacity size 1C that lithium-ion-power cell is discharged into final discharging voltage, shelve 3~5min, adopt the current charges 12min of nominal capacity size 1C, shelve 3~5min, adopt respectively 0.5C*n current discharge, to be 12S discharge time, the discharge voltage recording be electric discharge when voltage is set corresponding electric current be defined as maximum discharge current I
dis-max1, voltage is set is the difference Δ V that final discharging voltage value deducts the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment in electric discharge, wherein, and n ∈ [Isosorbide-5-Nitrae 0] and be positive integer.
Nominal capacity size 1C adopts the electric current of 1/3 size of lithium-ion-power cell rated capacity to the last discharge capacity in lithium-ion-power cell charge and discharge cycles 2~3 times.The nominal capacity of the lithium-ion-power cell providing due to battery producer is often less than its actual capability value, also has the difference of test environment and equipment, the value of lithium-ion-power cell 1C also can be different, for test result more accurate, so redefined in the present invention the nominal capacity size 1C of lithium-ion-power cell.
The current charges 12min that adopts nominal capacity size 1C, the electric weight that makes lithium-ion-power cell to be measured is 20%, rather than in the state of electric discharge completely, the battery polarization phenomenon can effectively prevent from again charging time.The charging interval is here the result obtaining after test of many times.
In the present embodiment, the method also comprises that measurement is 12S when discharge time, and discharge voltage is the Positive Poles of lithium-ion-power cell and the temperature in centre position of discharging when voltage is set, be greater than when meeting difference DELTA T1>=25 ℃, the Positive Poles temperature of temperature in Positive Poles and centre position that 50 ℃, the temperature in centre position are greater than any in 50 ℃ or when multiple, maximum discharge current is defined as I
dis-max, and I
dis-max=I
dis-max1-0.1C*a, wherein, a is 1,2,3.That is to say, step 205 also needs to meet temperature gap Δ T1≤25 ℃ in Positive Poles and centre position, and the temperature in Positive Poles and centre position is all not more than 50 ℃.
Correspondingly, at least 2 temperature sensors are installed on lithium-ion-power cell, 1 is fixed on battery centre position, and to gather the temperature data of lithium-ion-power cell center surface, another 1 is fixed on Positive Poles place and gathers anodal temperature data.
1/2 1/2 the position that adds Positive Poles height of the housing height that wherein, centre position is lithium-ion-power cell.Referring to Fig. 2 a, 41a and 41b are respectively both positive and negative polarity pole, 43 for test lead, 44 and 45 is that two temperature sensors, 46 are housing, 1/2 of the housing height that B is lithium-ion-power cell, and 1/2 of C Positive Poles height, A is centre position.
Step 206: 1/3 the electric current that adopts nominal capacity size 1C is to lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h.
To lithium-ion-power cell charge and discharge cycles 2~3 times, cycling complete and be full of electricity after shelve again 1~2h, its inner fully balance, material structure are recovered, eliminate the SEI(Solid Electrolyte Interface that polarization causes, solid electrolyte interface) film out-of-flatness, thus the accuracy of assurance test result.
Similarly, after step 206, also can adopt whether the variation in the voltage 30min that observes lithium-ion-power cell is 0, determine whether lithium-ion-power cell reaches stable state.
Step 207: adopt the electric current of nominal capacity size 1C to charge to charging upper limit voltage to lithium-ion-power cell, shelve 3~5min, the electric current that adopts nominal capacity size 1C is to the lithium-ion-power cell 18min that discharges, shelve 3~5min, adopt respectively 0.5C*m current charges, to the charging interval be 12S, the charging voltage recording be charging when voltage is set corresponding electric current be defined as maximum charging current I
charge-max1, voltage is set is the difference Δ V that charging upper limit voltage adds the terminal voltage of lithium-ion-power cell and the terminal voltage of testing equipment in charging, wherein, and m ∈ [Isosorbide-5-Nitrae 0] and be positive integer.
The current discharge 18min that adopts nominal capacity size 1C, the electric weight that makes lithium-ion-power cell to be measured is 70%, when preventing large current charge the excessive inside side reaction causing of battery polarization too much, the discharge time is here the result for obtaining after test of many times also.
In the present embodiment, the method also comprises: measuring when the charging interval is 12S, and charging voltage is the Positive Poles of charging when voltage is set and the temperature in centre position, be greater than when meeting the temperature of difference DELTA T2>=20 ℃, Positive Poles of temperature in Positive Poles and centre position that 45 ℃, the temperature in centre position are greater than any in 45 ℃ or when multiple, maximum charging current is I
charge-max, and I
charge-max=I
charge-max1-0.1C*b, wherein, b is 1,2,3.That is to say, step 207 also should meet temperature gap Δ T2≤20 ℃ in Positive Poles and centre position, and the temperature in Positive Poles and centre position is all not more than 45 ℃.
While realization, maximum discharge current I
dis-maxwith I
dis-max1, maximum charging current I
charge-maxwith I
charge-max1be integer, and meet fractional part>=0.8 o'clock carry, when fractional part <0.8, cast out.
In step 205 and 207, shelve 3~5min, preferably 5min.In order to guarantee the accuracy of the result of testing, the time of at every turn shelving all should be identical, for example, is 5min.It should be noted that, the time of shelving also can be subject to the impact of the conditions such as the accuracy of lithium-ion-power cell to be measured, therefore the time that can also shelve according to the suitable prolongation of concrete battery to be measured or shortening.
It should be noted that, in the process realizing, general to be strict with when discharge time be 12S, and discharge voltage and charging voltage must just in time equal respectively that electric discharge arranges voltage and charging arranges voltage.But because of the impact of test environment etc., discharge voltage now and charging voltage also can be respectively arrange voltage and charging arranges fluctuating of voltage in electric discharge.Hold intelligibly, this floats the smaller the better, and the rate that conventionally approaches should be 99.999%.
Below with the maximum charging current I of the 45Ah lithium-ion-power cell of box hat LiFePO 4 material
charge-maxwith maximum discharge current I
dis-maxputting deterministic process is that example describes step 201~206.Wherein, the charging upper limit voltage that battery producer provides is 3.7V, and final discharging voltage is 2.5V.
This lithium-ion-power cell is fixed on the both positive and negative polarity wire of testing equipment, after guaranteeing firmly, the internal resistance that contacts of test battery positive and negative electrode pole and measure traverse line, anodal and measure traverse line is 3m Ω, negative pole and measure traverse line are 0.8m Ω.By 1 temperature sensor position centerlock (referring to Fig. 2 a, the housing height of this battery is 180mm, and Positive Poles height is 20mm, (180+20/2)/2=95mm place that centre position is short transverse), another 1 is fixed on Positive Poles place simultaneously.
Open ambient temperature control power supply, make this lithium-ion-power cell shelve 4~5h under 25 ± 0.5 ℃ of environment.Then, open testing equipment power supply, the electric current of 1/3 size of the battery rated capacity 45Ah providing with producer makees 3 circles and stablizes charge-discharge test, after being full of electricity, shelve 1~2h, when the voltage of observing this battery in 30min be changed to 0 time, measure the terminal voltage of this battery and the terminal voltage of testing equipment with universal instrument, and calculate aforementioned both difference DELTA V, obtain Δ V=0.003V.Measure nominal capacity size 1C=45.5237Ah simultaneously.
Adopt 1C electric current by this battery discharge to 2.5V, shelve 5min, adopt the current charges 12min of nominal capacity size 1C, shelve 5min, adopt respectively 0.5C*n (wherein n=1,2,3 ..., 16) current discharge, it is 2.497V that electric discharge now arranges voltage.Test data is in table 1:
Table 1 maximum discharge current test data
Sequence number |
Electric current |
Time |
Corresponding voltage |
Anodal temperature |
Medium temperature |
ΔT |
1 |
22.7618A |
12S |
3.0135V |
25.07℃ |
25.53℃ |
0.46℃ |
2 |
45.5237A |
12S |
3.0110V |
25.97℃ |
26.74℃ |
0.77℃ |
3 |
68.2855A |
12S |
3.0091V |
28.08℃ |
29.94℃ |
1.86℃ |
…… |
? |
? |
? |
? |
? |
? |
14 |
341.4277A |
12S |
2.5333V |
32.41℃ |
38.97℃ |
6.56℃ |
15 |
364.1896A |
12S |
2.4971V |
33.25℃ |
41.72℃ |
8.47℃ |
16 |
386.9514A |
9.75S |
2.4968V |
35.22℃ |
44.92℃ |
9.7℃ |
Can find out the maximum discharge current I of this 45Ah LiFePO4 box hat battery by above-mentioned data
dis-max=364A.
After maximum discharge current has been tested, adopt 1/3 the electric current charge and discharge cycles 3 times of nominal capacity size 1C, after being full of electricity, shelve 1~2h, when observe the voltage of this battery in 30min be changed to 0 time, adopt the electric current of nominal capacity size 1C to charge to 3.7V to this battery, shelve 5min, adopt the electric current of nominal capacity size 1C to battery discharge 18min, shelve 5min, adopt respectively 0.5C*m (wherein, m=1,2,3 ..., 8) current charges, it is 3.703V that charging now arranges voltage.Test data is in table 2:
Table 2 maximum charging current test result one
Sequence number |
Electric current |
Time |
Corresponding voltage |
Anodal temperature |
Medium temperature |
ΔT |
1 |
22.7618A |
12S |
3.3933V |
25.07℃ |
25.01℃ |
-0.06℃ |
2 |
45.5237A |
12S |
3.4532V |
26.38℃ |
26.74℃ |
0.36℃ |
3 |
68.2855A |
12S |
3.4811V |
29.99℃ |
29.94℃ |
-0.05℃ |
…… |
? |
? |
? |
? |
? |
? |
7 |
182.0948A |
12S |
3.6924V |
39.75℃ |
41.11℃ |
1.36℃ |
8 |
203.5665A |
12S |
3.7036V |
45.96℃ |
47.73℃ |
1.77℃ |
As can be seen from Table 2 at I
charge-max1when=203.5665A, battery medium temperature is greater than 45 ℃, now, and I
charge-max=203.5665-0.1C*b, wherein, b=1,2,3.Test data is in table 3:
Table 3 maximum charging current test result two
Sequence number |
Electric current |
Time |
Corresponding voltage |
Anodal temperature |
Medium temperature |
ΔT |
1 |
199.0141A |
12S |
3.7003V |
44.07℃ |
45.01℃ |
0.94℃ |
2 |
194.4618A |
12S |
3.6991V |
43.33℃ |
44.68℃ |
1.35℃ |
3 |
189.9095A |
12S |
3.6972V |
43.71℃ |
44.44℃ |
0.73℃ |
As can be seen from Table 3 by the maximum charging current I of revised this 45Ah ferric phosphate lithium cell of temperature
charge-maxfor 194A.
The embodiment of the present invention is by under the low SOC state of lithium-ion-power cell, it is carried out to charging and discharging, do not damaging under the prerequisite of battery electrical property, by determining repeatedly in charge and discharge process, the time of discharging and recharging is 12S, and electric current when discharge voltage and charging voltage reach respectively final discharging voltage and charging upper limit voltage, accurately calculate maximum discharge current and maximum charging current that battery can bear, convenient, fast, data processing is simple, easily grasp, effectively avoid overcharging and overdischarge phenomenon of lithium-ion-power cell, guarantee the useful life of battery, reduce the cost of new-energy automobile, and be conducive to its popularization.In addition, maximum charge and discharging current can provide strong reference for the charging and discharging currents of the needs of lithium-ion-power cell reality accurately, and then solve its charging and discharging currents and select variety of issue unreasonable and that bring.
The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.