Comprehensive investigation of the lithium insertion mechanism of the Na2Ti6O13 anode material for Li-ion batteries

Sodium hexatitanate Na2Ti6O13 with a tunnel structure has been proposed to be an attractive anode material for lithium ion batteries because of its low insertion voltage, structural stability and good reversibility.

Unravelling the mechanism of lithium insertion into and extraction from trirutile-type LiNiFeF6 cathode material for Li-ion batteries

For possible future application as cathode material in lithium ion batteries, the lithium insertion mechanism of trirutile-type LiNiFeF6 was investigated.

Li3+δV6O13: a short-range-ordered lithium insertion mechanism

The structures of Li3V6O13 and Li3+δV6O13, δ ≃ 0.3, have been determined by single-crystal X-ray diffraction. Both compounds have the space group C2/m, with very similar cell parameters. In Li3V6O13, the Li atoms are found in the Wyckoff positions 4(i) and 2(b) with multiplicities of four and two, respectively. Since Li3V6O13 exhibits no superstructure reflections, it is concluded that Li3V6O13 contains one disordered lithium ion in an otherwise ordered centrosymmetric structure. On inserting more lithium into the structure, the Li3+δV6O13 phase is formed with the homogeneity range 0 < δ < 1. It is concluded that the site for the extra inserted lithium ion is closely coupled to the position of the disordered lithium ion in Li3V6O13. A mechanism for this behaviour and for the further formation of the Li6V6O13 end-phase in the Li x V6O13 system is proposed.