General LiFePO4 Degradation vs Temperature 1.01

Concerned about your LiFePO4 batteries Overheating or Freezingand losing ability to hold charge due to operating temperature?​

The Effect of Charging and Discharging Lithium Iron Phosphate-graphite Cells at Different Temperatures on Degradation​

7/18/2018​

Pouch cells (operational voltage range between 2.50 - 3.70 V) of a rated capacity of 6 Ah have been used for this study. The results obtained from their electrochemical characterization are divided into three sections:

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i) cycling at the same charging and discharging temperatures (step 1.1)

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ii) cycling at different discharging temperatures (and same charge temperature) (step 1.2) and

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iii) cycling at different charging temperatures (and same discharge temperature) (step 1.3).

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Long-term (aging)

1. Perform 100 charge/discharge cycles. Create a protocol for the battery cycler with the software, following steps 1.3.1 and 1.3.2. In this case, adjust the protocol steps to a CC-CV charging of 1 C up to 3.7 V (CV phase until 0.1 C or 1 h) and a CC discharging of 1 C current up to 2.7 V with a constant temperature during charge (Tc) and during discharge (Td).

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2. Follow steps 1.3.3 and 1.3.4 for the channel and protocol selection.

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3. Carry out the long-term aging at several temperature combinations (10) for the 100 charge/discharge cycles from step 3.3.1, in the temperature range from -20 °C to 30 °C (see the test matrix in Table 1) developed through DOE D-optimization36 (a minimum error of prediction). Set a rest time in the testing protocol of 30 min after each charging or discharging step when Tc and Td are the same (tests No. 1 and 2, 3 and 4, 9 and 10, 13 and 14, and 19 and 20, Table 1). However, when Tc and Td are different (tests No. 11 and 12, 5 and 6, 7 and 8, 15 and 16, and 17 and 18, Table 1), set a rest time until the temperature is stable within 1 Kh-1.

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4. Perform a reference cycle after each set of 25 cycles (see step 3.2). 5. Repeat each test once on a different fresh cell to assess its repeatability.

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