The stability and safety of SEB cells are further evident in high-voltage charge and high-temperature calendar life tests (figs. S1 and S2). The SEB cells can undergo 1254 exposures to high-voltage abuse [constant current (CC) charge to 4.4 V, constant voltage (CV) to C/20] at 40°C with a capacity retention of 80%, whereas the baseline cell sustains only 40 cycles at the same capacity loss and operating temperature, indicating that the SEB cell is >30× more stable and hence safer than the baseline cells under high-voltage charging conditions. Calendar life testing further shows that the passivated SEB cells can effectively suppress self-discharge. The self-discharge current is measured by holding the cell voltage constant at a required value, such as 4.187 V for 100% state of charge (SOC). Both baseline and SEB cells display a fast decrease of self-discharge current density in the beginning of calendar aging due to anode SEI layer growth. Fresh SEB cells show self-discharging currents ~5× lower than the baseline cell at room temperature and 50% SOC, 6× lower at room temperature and 100% SOC, and ~7× lower at 60°C at both 50 and 100% SOC. After 60 days of storage, the self-discharge current begins to plateau; however, the self-discharge current in the SEB cell is still 2× lower than that in the baseline cell at room temperature and 50% SOC and 3× lower at room temperature and 100% SOC. The self-discharge becomes 4× lower at high temperature (60°C) at both 50 and 100% SOC, indicating that at elevated temperatures, the SEB cells maintain superiority in calendar life over the baseline cell.