Solid-state electrolytes attract great attention due to their advantages in safety, electrochemical stability and battery packaging. High-voltage cathode materials and the Li metal anode further increase the energy density and electrochemical cycling properties.

Huang and Xu argue that the cyclo -N ₅ ^– ion in (N ₅ ) ₆ (H ₃ O) ₃ (NH ₄ ) ₄ Cl we described in our report is theoretically unfavorable and is instead protonated. Their conclusion is invalid, as they use an improper method to assess the proton transfer in a solid crystal structure. We present an in-depth experimental and theoretical analysis of (N ₅ ) ₆ (H ₃ O) ₃ (NH ₄ ) ₄ Cl that supports the results in the original paper.