Worried about your LiFePO4 batteries Overheating or Freezingand losing ability to hold charge due to operating temperature?This is a research paper that carries out charging and discharging at set temperatures, and evaluating the degree to which capacity degrades after cycling. Some tests are done with the same temperature for charging as discharging, and some tests are done with a different set temperature for charging vs discharging.
The Effect of Charging and Discharging Lithium Iron Phosphate-graphite Cells at Different Temperatures on Degradation
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:
i) cycling at the same charging and discharging temperatures (step 1.1)
ii) cycling at different discharging temperatures (and same charge temperature) (step 1.2) and
iii) cycling at different charging temperatures (and same discharge temperature) (step 1.3).
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).
2. Follow steps 1.3.3 and 1.3.4 for the channel and protocol selection.
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.
Hoping this document resource will help visitors evaluate temperature management for their LiFePO4 batteries.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.