A kind of test method improving LiFePO4 dynamic lithium battery cycle life
Technical field
The present invention relates to technical field of lithium ion, and in particular to a kind of improvement LiFePO4 dynamic lithium battery circulation longevity
The test method of life.
Background technique
In recent years, in the case where new-energy automobile encouragement policy persistently stimulates, the multiplication of new-energy automobile market demand, electric car
Come into the popularity stage.However, client is not only safety, course continuation mileage for the demand of electric car, also make
With the requirement in service life and charging time, this is also the key that can electric car popularize.
At this stage, the cycle life test of battery generallys use the side of GB/T31484-2015 testing standard cycle life
Method uses 1C constant-current constant-voltage charging, after standing, 1C constant-current discharge.With the aging of battery, the internal resistance of cell and polarization constantly increase
Add, constant-voltage phase when constant-current constant-voltage charging also obviously increases.And the trickle charge strategy of vehicle battery pack is substantially small multiplying power
Constant-current charge, without constant-voltage phase, the charging time, generally longer than 6 hours.On the one hand, prolonged cycle life evaluation and test affects
The development cycle of battery, on the other hand, being charged as many clients for a long time makes troubles, and becomes and hinder potential customers' purchase
Factor.
Summary of the invention
A kind of test method improving LiFePO4 dynamic lithium battery cycle life proposed by the present invention, can solve lithium battery
Cycle life is shorter and testing time longer technical problem.
To achieve the above object, the invention adopts the following technical scheme:
A kind of test method improving LiFePO4 dynamic lithium battery cycle life, two to three step constant-current charge of use and one
Constant-current discharge is walked, high current constant-current charge to platform voltage or more is wherein first used when constant-current charge, reuses low current constant current
Charge to charge cutoff voltage;After standing, constant-current discharge to discharge cut-off voltage.
Preferably, described its size of current of high current constant-current charge is the maximum allowable 0.8-1 for continuing charging current of battery
Times.
Preferably, more than the large current charge to platform voltage refer to that capacity reaches 50-90%SOC or voltage reaches
3.45-3.55V。
Preferably, described its size of current of low current constant-current charge is the maximum allowable 0.2- for continuing charging current of battery
0.5 times.
Preferably, the constant-current charge blanking voltage is 3.65V.
Preferably, the constant-current discharge size of current is the 1C of battery rated capacity.
Preferably, the constant-current discharge blanking voltage is 2.00V.
A kind of test method improving LiFePO4 dynamic lithium battery cycle life, including
As shown from the above technical solution, the invention proposes a kind of surveys for improving LiFePO4 dynamic lithium battery cycle life
Method for testing accelerates power of battery decaying and the service life declines because high-power charging cycle often will cause anode impedance increase
Subtract, which is charged by gradient, and the rate of charge for reducing charging latter end can improve to reduce the polarization of battery
The cycle life of battery, while substantially reducing battery charge time, and battery charge control strategy in actual use can be taken into account.
The beneficial effects of the present invention are:
The high current constant-current charge turns the loop test mode of low current constant-current charge, reduces the charging times of charging latter end
Rate, to reduce the polarization of battery, on the one hand, the test of cycle life can be shortened on the basis of guaranteeing battery cycle life
Period;On the other hand, this method can be provided for the charge control strategy of vehicle and effectively be built closer to the charging modes of vehicle
View.
Detailed description of the invention
Fig. 1 is the method for the present invention flow chart;
Fig. 2 is the loop-around data of test of the embodiment of the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.
As shown in Figure 1, a kind of test method of improvement LiFePO4 dynamic lithium battery cycle life of the embodiment of the present invention,
The following steps are included:
S10, it is charged to mesuring battary more than or equal to platform voltage with high current constant current;
S20, use low current constant-current charge to charge cutoff voltage again;
S30, it stands for the first time;
S40, constant-current discharge to discharge cut-off voltage is used;
S50, it stands for second.
According to above-mentioned steps, specific test case is as follows:
Comparative example
Under the conditions of 25 DEG C of room temperature, the cylinder ferric phosphate lithium cell that rated capacity is 12Ah is followed according to following work step
Ring life test: 1) 0.5C constant-current charge to 3.65V, constant-voltage charge to 0.05C (charging time about 2h5min);2) it stands
10min;3) 1C constant-current discharge is to 2.00V;4) 10min is stood.Capacity retention ratio in record circulation, test result are shown in Table 1.
Embodiment 1
Under the conditions of 25 DEG C of room temperature, the cylinder ferric phosphate lithium cell that rated capacity is 12Ah is followed according to following work step
Ring life test: 1) 1C constant-current charge to 3.5V, 0.5C constant-current charge to 3.65V (charging time about 1h16min);2) it stands
10min;3) 1C constant-current discharge is to 2.00V;4) 10min is stood.Capacity retention ratio in record circulation, test result are shown in Table 1.
Embodiment 2
Under the conditions of 25 DEG C of room temperature, the cylinder ferric phosphate lithium cell that rated capacity is 12Ah is followed according to following work step
Ring life test: 1) 0.8C constant-current charge to 3.55V, 0.5C constant-current charge to 3.65V (charging time about 1h23min);2) quiet
Set 10min;3) 1C constant-current discharge is to 2.00V;4) 10min is stood.Capacity retention ratio in record circulation, test result are shown in Table 1.
Embodiment 3
Under the conditions of 25 DEG C of room temperature, the cylinder ferric phosphate lithium cell that rated capacity is 12Ah is followed according to following work step
Ring life test: 1) 1C constant-current charge to 3.45V, 0.5C constant-current charge to 3.55V, 0.2C constant-current charge to 3.65V is (when charging
Between about 1h44min);2) 10min is stood;3) 1C constant-current discharge is to 2.00V;4) 10min is stood.Capacity in record circulation is kept
Rate, testing procedure is as shown in table 1, and loop-around data is as shown in Figure 1.
Comparison/embodiment |
Loop test charging work step |
Comparative example |
0.5C constant-current charge is to 3.65V, constant-voltage charge to 0.05C |
Embodiment 1 |
1C constant-current charge is to 3.5V, 0.5C constant-current charge to 3.65V |
Embodiment 2 |
0.8C constant-current charge is to 3.55V, 0.5C constant-current charge to 3.65V |
Embodiment 3 |
1C constant-current charge is to 3.45V, 0.5C constant-current charge to 3.55V, 0.2C constant-current charge to 3.65V |
Table 1
It can be seen that, the method that high current constant-current charge of the invention turns low current constant-current charge, recycle in conjunction with table 1 and Fig. 1
Data can shorten under the premise of guaranteeing battery cycle life and follow better than the method for the constant-current constant-voltage charging that this battery core is recommended
The ring test time.
The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations;Although with reference to the foregoing embodiments
Invention is explained in detail, those skilled in the art should understand that: it still can be to aforementioned each implementation
Technical solution documented by example is modified or equivalent replacement of some of the technical features;And these modification or
Replacement, the spirit and scope for technical solution of various embodiments of the present invention that it does not separate the essence of the corresponding technical solution.