A₃Ti₅NbO₁₄ (A = H, Li and K) family: ionic exchange, physical and electrochemical properties

A new layered titanoniobate, Li3Ti5NbO14, a member of the A(x)M(2n)O(4n+2) family, has been synthesized using a molten salt reaction between H3Ti5NbO14 and an eutectic mixture of LiOH and LiNO3. This compound crystallizes in the P2(1)/m space group with a = 9.273(15) & Aring;, b = 3.788(6) & Aring;, c = 8.871(3) & Aring;, and beta = 114.33(1)degrees, as determined by 3D electron diffraction single crystal analysis. It exhibits [Ti5NbO14](3-) layers similar to K3Ti5NbO14, but differs from the latter by a 'parallel configuration' of its [Ti5NbO5](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+.