Nat. Rev. Mater. doi:10.1038/natrevmats.2016.13 Figure 3 Structures and electrochemical voltage profiles of advanced layered cathode materials Part b is adapted with permission from Johnson, C. S., Li, N., Le­fief, C., Vaughey, J. T. & Thackeray, M. M. Synthesis, characterization and electrochemistry of lithium battery electrodes: xLi2MnO3·(1−x) LiMn0.333Ni0.333Co0.333O2 (0 ≤ x ≤ 0.7). Chem. Mater. 20, 6095–6106 (2008), American Chemical Society; and is adapted from Lee, K.‑S., Myung, S.‑T., Amine, K., Yashiro, H. & Sun, Y.‑K. Structural and electrochemical properties of layered Li[Ni1−2xCoxMnx]O2 (x = 0.1– 0.3) positive electrode materials for Li‑ion batteries. J. Electrochem. Soc. 154, A971–A977 (2007), reproduced by permission of the Electrochemical Society. Part d is adapted from Nayak, P. K., Grinblat, J., Levi, M., Mark­ovsky, B. & Aurbach, D. Structural and electrochemical evidence of layered to spinel phase transformation of Li and Mn rich layered cathode materials of the formulae xLi[Li1/3Mn2/3]O2·(1−x) LiMn1/3Ni1/3Co1/3O2 (x = 0.2, 0.4, 0.6) upon cycling. J. Electrochem. Soc. 161, A1534–A1547 (2014), reproduced by permission of the Electrochemical Society. Choi, J. W. & Aurbach, D. (2016) Promise and reality of post-lithium-ion batteries with high energy densities Nat. Rev. Mater. doi:10.1038/natrevmats.2016.13