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Effect of Charge Ratio on Decay of Lithium Ion Batteries Views [0] Published: 2017-09-21 17:52:21

Lithium-ion rechargeable batteries in the use of the process with the increase in the number of charge and discharge, the capacity gradually reduced, that is, we said the decline, the intuitive feeling is that power is not enough.

 Like our mobile phone, just bought time, full of electricity can be used for a whole day, but as we use may be full of electricity can only support the use of half a day, and this is the use of lithium-ion battery capacity decline, This is for the consumer electronics products such as the replacement of the relatively fast product is still better resolved, the battery capacity decline is too large before, we may have replaced the new mobile phone, but for the electric car this longer life durable The product is not so easy to solve, in general, the car's life of up to 10 years, during which may be about 1000 to 2000 times the charge (assuming a charge every other day), in order to meet the consumer The use of electric vehicles demand, it must be on the life of lithium-ion battery electric vehicles put forward certain requirements.

A lot of factors effect the life of lithium-ion battery , the use of temperature, charge and discharge current, charge and discharge cut-off voltage and other factors will affect the decline of lithium-ion battery speed. The mechanism of lithium ion battery capacity decline can also be divided into three categories: internal resistance and polarization increase, positive and negative active material loss, Li loss, different external factors on the impact of these three are also different.

 For example, LiFePO4 material battery has a very good cycle performance, but the United States, Texas University, Arlington, DerekN.Wong and other research found that the use of conditions on its cycle life has an important impact, when DerekN.Wong 26650 models LiFePO4 battery for 15C pulse discharge and 15C continuous discharge, the two discharge system for LiFePO4 battery has a completely different impact. 15C pulse discharge lithium iron phosphate battery capacity decline is very fast, 40 times after the 15C discharge can not be, but still able to carry out 1C discharge, 1C discharge decay rate of 6% / 20 times. And 15C continuous discharge battery capacity decline slow, 60 times after the 15C discharge is still able to, but 1C rate of decline rate faster than 15C pulse discharge, reaching 14% / 20 times. The mechanism studies show that the 15C pulsed discharge cell contains more LiF in the SEI film of the negative electrode, and LiF has a greater resistance to lithium ion diffusion, resulting in a rapid increase in the Li + diffusion impedance and charge exchange impedance of the cell, During the discharge process, the polarization voltage is too large, which leads to the rapid decline of LiFePO4 high current discharge capacity.

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