The cell Li 0-1 VO 2 vs Li 0-1 VS 2 is worth considering further: its theoretical cell viability is 1, indicating that three out of the four end-member phases are labelled as having been observed. The only virtual phase is the delithiated, layered PEAM VO 2 (mp-714944). An analysis of the present literature shows that the delithiation of layered (R 3m) LiVO 2 was first attempted by de Picciotto et al. in 1984, demonstrating "a shift from trigonal to near-cubic lattice constants" upon delithiation, explained by the authors as a migration of the vanadium ions, that makes it an impractical electrode material. The same process has been studied more recently by Chable et al . A possible experimental way to circumvent this issue could be the introduction of a support cation, to hinder V anions migration, according to the work of Ma et al. Such a strategy was validated in the same work with the use of LiCr x V 1-x O 2 with x ranging from 0.1 to 0.5, and the authors also point out the partial substitution of V with Ga(III) and Al(III). The improvement to cyclability is crucial, but it comes at the expenses of capacity, yielding a practical discharge capacity at the tenth cycle of about 100 mA h g -1 , to be compared to the theoretical capacity of the complete delithiation of R 3m LiVO 2 amounting to 298 mA h g -1 .