Solid-state self-template synthesis of Ta-doped LiZnTiO spheres for efficient and durable lithium storage.

Ta-doped LiZnTiO (LZTO) spheres (LiZnTi Ta O; where is the synthetic chemical input,  = 0, 0.03, 0.05, 0.07) are synthesized via solid-state reaction using mesoporous TiO spheres as the self-template. The majority of Ta ions are uniformly doped into crystal lattices of LZTO through the Ti↔Ta substitution, and the rest forms the piezoelectric LiTaO secondary phase on the surface, as confirmed by X-ray diffraction refinement, Raman spectroscopy, density functional theory, and electron microscopy. Electrochemical impedance spectroscopy demonstrates that the Ta doping creates rapid electronic transportation channels for high Li ion diffusion kinetics; however, the LiTaO surface coating is beneficial to improve the electronic conductivity. At the optimal  = 0.05, LiZnTi Ta O spheres exhibit a reversible capacity of 90.2 mAhg after 2000 cycles with a high coulombic efficiency of ≈100% at 5.0 A/g, thus enabling a promising anode material for lithium-ion batteries with high power and energy densities.