## 4 Results and Discussion
### Experiment Results  
Figure 4 presents the voltage variations during the discharge. Figure 4a-d represent the results at different storage temperatures for 30, 45, 60, and 90 days, respectively. Herein, as the results of three samples were basically the same, one sample was randomly selected for display. It can be found that the discharge time at 25 and \(0\)\({}^{\circ}\)C is longer under the same storage time, and it does not change with storage time (Figure 4). At 45 \({}^{\circ}\)C and 54 \({}^{\circ}\)C, the discharge time decreases successively and the rate of decrease increases with the increase of storage time. Moreover, the discharge voltage is unstable and the platform voltage becomes short after 45 days of storage at 54 \({}^{\circ}\)C.  
Figure 5 represents the capacity retention over storage time at different temperatures. Here, three independent cells were tested at each sample point to ensure the reliability of experimental data. It is obvious that the value of capacity retention fluctuates around 1 at 0 \({}^{\circ}\)C and 25 \({}^{\circ}\)C, whereas it apparently decreases over storage time at 45 \({}^{\circ}\)C and 54 \({}^{\circ}\)C. The higher temperature corresponds to the rapid decrease in capacity retention, which is due to the fact that high temperature promotes the rate of chemical reactions inside the cell. In general, it can be concluded that a high-temperature storage environment leads to rapid capacity decay.  
Figure 3: The flow chart of the discharge experiments.  
Figure 4: The discharge voltage curves of batteries stored at different temperatures for (**a**) 30 days; (**b**) 45 days; (**c**) 60 days; and (**d**) 90 days.  
Figure 5: The capacity retention vs. storage time at different temperatures. Different symbols represent three cell samples at the same storage temperature and time.  
Figure 6 presents the discharge voltage curves at different temperatures and current rates. Figure 6a-d correspond to the environment temperature of \(-10\)\({}^{\circ}\)C, \(0\)\({}^{\circ}\)C, \(25\)\({}^{\circ}\)C, and \(40\)\({}^{\circ}\)C in the discharge process, respectively. It can be found that the discharge voltage is more stable and the voltage platform period is longer at high temperatures. In other words, ER48690 exhibits better stability at high temperatures. Figure 7 presents the battery capacity at different temperatures and current rates. To display the impact of both factors on capacity intuitively, the capacity vs. temperature and capacity vs. current rate are plotted in Figure 7a,b, respectively. The capacity value at \(40\)\({}^{\circ}\)C and \(4.4\) A does not conform to the overall behavior, so it is treated as an outlier. Overall, the effect of temperature on battery capacity is significant, whereas the current rate renders a negligible influence on battery capacity. In the temperature range of \(0\) to \(25\)\({}^{\circ}\)C, the maximum available capacity of the battery increases with the increase of temperature, whereas it remains basically at \(>\)\(25\)\({}^{\circ}\)C and \(<\)\(10\)\({}^{\circ}\)C. Hence, ER48690 exhibits stable performance at high and low temperatures.  
Figure 6: The discharge–voltage curves at different current rates and (**a**) \(-10\)\({}^{\circ}\)C; (**b**) \(0\)\({}^{\circ}\)C; (**c**) \(25\)\({}^{\circ}\)C; and (**d**) \(40\)\({}^{\circ}\)C.