Alkali hexatitanates—A 2Ti 6O 13 (A = Na, K) as host structure for reversible lithium insertion

Abstract

Electrochemical lithium insertion into two isostructural titanium-based oxides, K 2Ti 6O 13 and Na 2Ti 6O 13 has been investigated. Although the two compounds differ mainly from their particle size and cell volume, pronounced differences in the insertion mechanism have been evidenced. They can accommodate about three Li per formula unit at relatively low potentials (1.5–0.9 V versus Li reference), which qualifies them as potential alternatives to Li 4Ti 5O 12. The main limitations are their rate capabilities and capacity retention related to large particles and parasitic electrolyte decomposition, respectively.