LiVO2 as a new solid-state phase change material

•Off-stoichiometry systematically modifies the properties of phase change material for LixVO2+δ.•The latent heat reached a maximum at the stable valence of V for the formation of the V3 trimer.•The phase transition temperature decreased monotonically with V–V distance.•The hysteresis of phase transition reduces for longer V–V distance. [Display omitted] Herein, we study the effect of off-stoichiometry on the properties of a phase change material (PCM)—LiVO2—which is a new type of PCM based on the phase change of electron. The PCM properties such as latent heat, transition temperature, and hysteresis of transition temperature varied linearly with respect to the distance of vanadium ions, which was systematically controlled through off-stoichiometry in the composition of LixVO2+δ (0.85