Fig. 2: Phase stabilities of protonated and relithiated NCM materials.
From: Proton-exchange induced reactivity in layered oxides for lithium-ion batteries
a Calculated binary phase diagram of protonation of (c) LixH1-x(NiCoMn)O2. b Calculated phase diagram of LixHy(NiCoMn)1/3O2 (0 ≤ x,y ≤ 1) as a function of pH and \({\mu }_{{{{\rm{Li}}}}^{+}}\). Regions with solid phases are shaded in lake blue. c Changes of ∆G of Li(NiCoMn)1/3O2 as a function of concentration of LiOH solution. d Calculated binary phase diagram of protonation of LixH1-x(Ni0.8Co0.1Mn0.1)O2 (x = 0 ~ 1.0). e Calculated phase diagram of LixHyNi0.8Co0.1Mn0.1O2 (0 ≤ x,y ≤ 1) as a function of pH and \({\mu }_{{{{\rm{Li}}}}^{+}}\). Regions with solid phases are shaded in lake blue. f Changes of ∆G of LiNi0.8Co0.1Mn0.1O2, HNi0.8Co0.1Mn0.1O2 and Li0.11H0.89Ni0.8Co0.1Mn0.1O2 as a function of concentration of LiOH solution. A material that is thermodynamically stable under certain conditions in an aqueous environment has ∆G = 0 eV/cation. A larger ∆G indicates higher possibility of a material to decompose into combinations of stable species indicated on phase diagram. Based on previous studies by Singh et al., materials with ∆G < 0.5 eV/cation is able to resist dissolution, particularly when bulk solid-state transformations are involved18. The phase of NCM in region ① presents Ni2+, Co2+ and Mn2+; region ② presents Co(OH)2(s), Ni2+and Mn2+; region ③ presents Co(OH)2, Ni(OH)2 and Mn2+; region ④ presents Co(OH)2, Ni(OH)2 and MnHO2; region ⑤ presents Co3O4, Ni(OH)2 and MnHO2; region⑥ presents region Co3O4, Ni(OH)3- and MnHO2; region ⑦ presents Co3O4, Ni(OH)42- and MnHO2; region ⑧ presents Li(NiCoMn)1/3O2; region ⑨ presents LiNi0.8Co0.1Mn0.1O2. Source data are provided as a Source Data file.
