The lithium intercalation process in the low-voltage lithium battery anode Li₁+_xV₁-_xO₂

Lithium can be reversibly intercalated into layered Li_1+xV_1−xO₂ (LiCoO₂ structure) at ∼0.1 V, but only if x>0. The low voltage combined with a higher density than graphite results in a higher theoretical volumetric energy density; important for future applications in portable electronics and electric vehicles. Here we investigate the crucial question, why Li cannot intercalate into LiVO₂ but Li-rich compositions switch on intercalation at an unprecedented low voltage for an oxide? We show that Li⁺ intercalated into tetrahedral sites are energetically more stable for Li-rich compositions, as they share a face with Li⁺ on the V site in the transition metal layers. Li incorporation triggers shearing of the oxide layers from cubic to hexagonal packing because the Li₂VO₂ structure can accommodate two Li per formula unit in tetrahedral sites without face sharing. Such understanding is important for the future design and optimization of low-voltage intercalation anodes for lithium batteries.