Figure 3C shows the relative power of SEB cells versus the baseline LIB, where the power of the baseline cell at room temperature is normalized to be unity, thus demonstrating that SEB cells can provide sufficient, higher power by operating at higher temperatures. At 50% SOC, SEB-1 operated at 29.2°C provides the same power as the baseline cell at room temperature. The safest cell, SEB-3, with 1.5 wt % TAP additive requires an operation temperature of 44.6°C to deliver the same power as the baseline cell at room temperature. The baseline cell has a narrow temperature window of 15° to 35°C, whereas the SEB cells have much higher maximum operating temperature without becoming excessively reactive. Thus, the necessity of higher temperature operation for power recovery does not pose an issue for SEB cells. At 50% SOC, the discharge power boost over the baseline Li-ion cell is 2.05, 1.81, and 1.39 for the SEB-1, SEB-2, and SEB-3, respectively (Fig. 3C). Moreover, at the ambient temperature of 0°C, the baseline LIB cell has a relative power of 0.38, while SEB-2 has a relative power of 1.81 when operated at 60°C [it takes 30 s to heat up a cell from 0° to 60°C at a speed of 2°C/s, typical of the self-heating structure of Wang et al. (1)]. This is ~5× boost in power over the LIB cell for SEB cells working in the freezing environments. Generally, SEB cells perform independent of ambient temperatures or weather, as they are always heated up in a matter of seconds and operate at a constant elevated temperature. Although heating a cell to an elevated temperature consumes cell energy, the total deliverable energy of a cell, counterintuitively, is not reduced. As shown in fig. S3, the C/3 discharge energy was 9.62 watt-hours (Wh) for the baseline cell at room temperature and 10.15 Wh for the SEB-3 cell at 60°C. According to our previous work (1), it takes ~1% cell energy for a 10°C temperature rise, meaning that the SEB-3 cell needs 3.5% of its energy for heating from 25° to 60°C; the remaining discharge energy is thus 9.79 Wh, which is 2% higher than that of the baseline cell at room temperature.