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Battery use environment

Author: Source: Datetime: 2016-10-07 08:53:53

Lithium-ion battery use of the environment on its cycle life is also very important. Among them, the ambient temperature is a very important factor. Ambient temperature is too low or too high will affect the LiFePo4 battery pack cycle life. 

Chen Jitao and other research of C / LiCoO2 lithium-ion battery at -20 ℃ under the conditions of charge and discharge performance. The results show that the discharge performance of the battery deteriorates at low temperature, the discharge capacity of 0.2C is only 77% of the normal temperature, and the discharge capacity of 1C is only 4% of the discharge capacity of 0.2C. Low-temperature constant-voltage charging time increases, charging performance is also significantly worse.

The main reasons for the decrease in the discharge capacity of the lithium ion battery at low temperatures include deterioration of the conductivity of the electrolyte, deterioration of the wettability and / or permeability of the separator, slowing of the migration speed of the lithium ions, charge transfer at the electrode / electrolyte interface Rate slowing down. In addition, the impedance of the SEI film increases at a low temperature, making the rate of lithium ions passing through the electrode / electrolyte interface slow. 

battery use enviornment

The reason for the increase of the impedance of the SEI film is that the lithium ions are easily removed from the negative electrode at a low temperature, and the insertion is difficult. The battery can be used in solar powered portable generator. Charging lithium metal will occur and react with the electrolyte to form a new SEI membrane covered in the original SEI membrane, the battery impedance increases, resulting in decreased battery capacity.

Li Lianxing, etc. on the same batch of lithium batteries at 60 ℃ and room temperature for 300 charge and discharge cycle experiments. In the initial stage, the battery exhibited a high discharge capacity at 60 ° C. But with the cycle, the battery capacity deceleration to accelerate, reduce the stability of the cycle, the late battery bulge even occur. The charge-discharge cycle of Li-ion battery is unstable under high temperature. The high electrochemical polarization of the electrode and the generation of gas are caused by the high temperature, and the charge transfer resistance is increased and the ion transport dynamics is decreased.

At present, most of Li-ion batteries use LiPF6 as the electrolyte, electrolyte impure or trace water catalytic decomposition of conductive salt, the electrolyte contains a certain acidic substances HF. HF reacts with the main components ROLi, ROCO2Li, etc. in the SEI film, and LiF is deposited on the surface of the negative electrode. The LiI-containing SEI film hinders the migration of lithium ions. At the same time, the resulting high-impedance material will isolate the insulation between the graphite particles. With the high temperature charge and discharge, the negative performance will gradually deteriorate and eventually lead to battery failure. 

Equipment using lithium-ion batteries in the transport or normal work, it may be subjected to vibration, shock, collision and other conditions of the test. Some lithium batteries communicate with the system to charge and discharge and receive data according to a certain frequency information. And usually portable solar power generator also need these batteries.

The frequency of the device vibration may interfere with the battery frequency, causing the chip data error or trigger protection circuit action. Strong vibration or shock, the lithium-ion battery's ears, external wiring, terminal, solder joints may be broken or off, the battery pole active material may also peel off, which will affect the battery life and even dangerous Happening.

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