A novel layered titanoniobate LiTiNbO5:: Topotactic synthesis and electrochemistry versus lithium

A new layered titanoniobate, LiTiNbO5, an n) 2 member of the A(x)M(2n)O(4n+2) family, has been synthesized using a molten salt reaction between HTiNbO5 and an eutectic LiOH/LiNO3. This compound crystallizes in the P2(1)/m space group with a) 6.41 angstrom, b) 3.77 angstrom, c) 8.08 angstrom, and beta = 92 degrees. It exhibits vertical bar TiNbO5 vertical bar(infinity) layers similar to HTiNbO5, but differs from the latter by a parallel configuration of its vertical bar TiNbO6 vertical bar(infinity) 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 0.8 lithium through a first-order transformation leading to a capacity of 94 mAh/g at a potential of 1.67 V vs Li/Li+.