fig2

Figure 2. Comparisons of O3 and P2 cathode materials from different aspects. (A) Crystal structure of P2 and O3 layered oxides; (B) Cationic potential rule to determine the formation of P2 and O3 structures. Reproduced with permission, Copyright 2020^[24], American Association for the Advancement of Science; (C) Na diffusion pathways and barriers in P2 and O3 cathodes. Reproduced with permission, Copyright 2017^[23], Wiley-VCH; (D) Structural evolutions of P2 and O3 cathodes under electrochemical Na extraction/insertion. Reproduced with permission, Copyright 2022^[26], Wiley-VCH. Reproduced with permission, Copyright 2018^[29], Wiley-VCH; (E) Air storage properties of typical P2 and O3 cathode materials. Reproduced with permission, Copyright 2018^[35], American Chemical Society. Reproduced under terms of the CC-BY license, Copyright 2020^[37], The Authors, Nature Publishing Group.