However, the O'3 phase feature located at 5.6° (reflection 111 O'3 ) is not visible above 4.0 V, and only a characteristic reflection of 101 O'3 (marked by the magenta dashed box in Figure ) can be observed above 4.0 V, which is present throughout the high voltage region. At the fully charged state, a new reflection located at 2.4° is generated and becomes the main phase. This feature is similar to the "X" phase proposed by Tarascon et al., and allows a moderate decrease (about 8.27%) in the c lattice parameter.