Fig. 3: Chemical stability towards lithium metal and air.
a, Calculated thermodynamics intrinsic electrochemical windows of vacancy-rich β-Li3N and other common SSEs, including oxides (that is, La3Li7O12Zr2 (LLZO), 0.03–3.16 V; lithium lanthanum titanate (LLTO), 1.80–3.73 V; Li1.3Al0.3Ti1.7(PO4)3 (LATP), 2.19–4.20 V), sulfides (that is, Li10GeP2S12 (LGPS), 1.71–2.29 V; Li6PS5Cl, 1.71–2.13 V) and halides (that is, Li3YCl6, 0.65–4.25 V; Li3InCl6, 2.28–4.42 V). b,c, SEM images of the vacancy-rich β-Li3N (b) and the vacancy-rich β-Li3N sample after contact with lithium (c). d, Normalized nitrogen K-edge XANES spectra of pristine vacancy-rich β-Li3N and the vacancy-rich β-Li3N sample after contact with lithium. N K-edge XANES spectra were collected in the TEY mode. e, Operando XRD pattern evolution of vacancy-rich β-Li3N during the exposure process to air with 25% relative humidity for 10 h, acquired at 30 min intervals over a 10 h period. f, In situ XRD pattern evolution of vacancy-rich β-Li3N upon different exposure times in a dry room with a low dew point of −50 °C to −60 °C (<0.3% relative humidity) for 150 h. Notably, the broad hump at approximately 26 degrees 2θ corresponds to the Kapton tape used in the sample preparation, which does not exhibit distinct sharp XRD peaks. g, The lithium-ion conductivity evolution at 25 °C of vacancy-rich β-Li3N after different exposure times in a dry room with a low dew point of −50 °C to −60 °C (<0.3% relative humidity) and ambient air with 3–5% humidity level for 150 h.
