Enhancing lithium ion diffusion kinetic in hierarchical lithium titanate@erbium oxide from coating to doping via facile one-step co-precipitation

Hierarchical lithium titanate@erbium oxide (Li 4 Ti 5 O 12 @Er 2 O 3 ) microspheres from coating to doping were successfully synthesised by a simple and scalable one-step co-precipitation method. Microscopic observations revealed that the Li 4 Ti 5 O 12 @Er 2 O 3 microspheres present a well-defined hierarchical structure and that Li 4 Ti 5 O 12 is coated by the Er 2 O 3 layer. The X-ray photoelectron spectroscopy (XPS) results demonstrate that partial Ti 4+ is reduced to Ti 3+ and induces oxygen vacancy because partial Er 3+ dope into octahedral 16d Li + /Ti 4+ sites of Li 4 Ti 5 O 12 . Owing to the hierarchical microsphere structure, Er 2 O 3 coating, and Er 3+ doping, the material exhibits excess rate capacity (183.7 mAh g −1 at 30C). The hierarchical microsphere structure shortens the diffusion pathways for Li + ions. The Er 2 O 3 coating on the surface reduces the adverse interface reaction . Importantly, oxygen vacancy induced by Er 3+ doping enhances Li + ion diffusion kinetics and offers extra space to store Li + ions, which endows this sample with excess rate capacity.