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Page 10 of 14 Shi et al. Energy Mater 2023;3:300036 https://dx.doi.org/10.20517/energymater.2023.27

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Figure 3. Cycling of Li/NMC111 cells at 20 °C. (A) 0.25 mA cm , (B) 0.5 mA cm , and (C) 1 mA cm .
to C/8, C/4, and 1C, respectively. As can be seen, the cycling is very stable at all of these current densities.
Long-term cycling (up to 500 cycles) was possible and is shown for the two higher current rates in
Supplementary Figure 3.

The state-of-the-art for automotive applications has shifted from NMC to NMC , which is, at the same
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time, less costly in terms of raw materials, less toxic, and more ethical considerations. NMC achieves these
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benefits by incorporating the lower Co content while providing higher energy densities. Thus, we also
constructed LiǁNMC cells and their behavior at 20 °C, as shown in Figure 4A and B. The rate performance
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is good up to C/2 with capacities above 120 mAh g , and most importantly, for lithium metal cells, the
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relatively high rates used for the rate test do not induce any decay of performance upon returning to C/2.
LiǁNMC cells were also cycled at 0 °C, as shown in Figure 4C and D. The rate performance obviously
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decays with temperature, but high capacities are still reachable at low rates (ca. 80 mAh g at C/2). Long-
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term stable cycling for more than 300 cycles was also obtained at both 20 °C and 0 °C after the rate test
[Supplementary Figure 4]. This is even more remarkable since elevated dis-/charge rates usually have a
strong detrimental effect on the long-term cycling performance of lithium metal cells when using
electrolytes that do not prevent dendrite growth.

Since the electrolyte membrane contains PC, the electrolyte is still flammable, although PC exhibits a much
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lower vapor pressure (0.2936 kPa at 25 °C ) than the linear alkyl carbonates commonly used in Li-ion