A 3 Ti 5 NbO 14 (A = H, Li and K) family: ionic exchange, physical and electrochemical properties.

A new layered titanoniobate, Li 3 Ti 5 NbO 14 , a member of the A x M 2 n O 4 n +2 family, has been synthesized using a molten salt reaction between H 3 Ti 5 NbO 14 and an eutectic mixture of LiOH and LiNO 3 . This compound crystallizes in the P 2 1 / m space group with a = 9.273(15) Å, b = 3.788(6) Å, c = 8.871(3) Å, and β = 114.33(1)°, as determined by 3D electron diffraction single crystal analysis. It exhibits [Ti 5 NbO 14 ] 3- layers similar to K 3 Ti 5 NbO 14 , but differs from the latter by a 'parallel configuration' of its [Ti 5 NbO 5 ] 3- ribbons between the two successive layers. The topotactic character of the reaction suggests that exfoliation plays a prominent role in the synthesis of this new form. This new phase intercalates reversibly 2 lithium through a first-order transformation leading to a capacity of 100 mA h g -1 at a potential of 1.67 V vs . Li/Li + .