The electrochemical intercalation of lithium into chromium (V)-containing oxides isostructural with β- and γ-Li3PO4 has been studied. β-Li3CrO4 can reversibly intercalate around 1 mole of Li ions per formula unit to give Li3 + xCrO4: 0 <x <1 with a discharge capacity of 196 mAh g-1; electrochemical data indicate the possible existence of a two-phase region in the approximate range 0.3 <x <0.8. Fully intercalated material appears to have a γ-related structure. γ-Li3.5Cr0.5Ge0.5O4, with a LISICON structure can reversibly intercalate up to 0.5 moles of Li ions per formula unit to give Li3.5 + xCr0.5Ge0.5O4: 0 <x <0.5. During intercalation, the γ-phase transforms into a β-phase which is retained on deintercalation. The volume changes associated with (de) intercalation of both β and γ structures are small, ≪ 1%. During the β → γ transition, the orthorhombic c axis, and the unit cell volume, increase by ~ 2%.
- Lithium insertion