The defect thiospinel Cu0.07[Ti2]S4was prepared by low-temperature oxidative extraction of copper from Cu[Ti2]S4. Up to two equivalents of lithium can be inserted into Cu0.07[Ti2]S4reversibly with fast electrochemical kinetics at room temperature; the defect thiospinel is, therefore, a highly promising alternative to layered TiS2as a cathode material for lithium secondary batteries. Samples of Cu1-x[Ti2]S4(0≤ x ≤ 0.93) and LixCu0.07[Ti2]S4(0 < x < 2) were prepared and characterised by65Cu and7Li solid-state NMR, neutron powder diffraction, and electrochemical measurements. Cu0.07[Ti2]S4is a semimetal with the residual copper located on the normal spinel A-cation sites. The lithium in LixCu0.07[Ti2]S4is located only in the 16c octahedral sites of the spinel framework at all lithium compositions. The open-circuit voltage of LixCu0.07[Ti2]S4versus lithium metal is nearly identical to that of layered LixTiS2over the whole lithium-composition range. The chemical diffusion constant of lithium in LixCu0.07[Ti2]S4(0.5 ≤x≤ 1.5) was found to be 1 × 10-9cm2s-1, which is comparable with that in layered LixTiS2. © 1989.
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