Zr⁴⁺ doping in Li₄Ti₅O₁₂ anode for lithium-ion batteries: Open Li⁺ diffusion paths through structural imperfection

One-dimensional nanomaterials have short Li⁺ diffusion paths and promising structural stability, which results in a long cycle life during Li⁺ insertion and extraction processes in lithium rechargeable batteries. In this study, we fabricated one-dimensional spinel Li ₄Ti₅O₁₂ (LTO) nanofibers using an electrospinning technique and studied the Zr⁴⁺ doping effect on the lattice, electronic structure, and resultant electrochemical properties of Li-ion batteries (LIBs). Accommodating a small fraction of Zr⁴⁺ ions in the Ti⁴⁺ sites of the LTO structure gave rise to enhanced LIB performance, which was due to structural distortion through an increase in the average lattice constant and thereby enlarged Li⁺ diffusion paths rather than changes to the electronic structure. Insulating ZrO₂ nanoparticles present between the LTO grains due to the low Zr⁴⁺ solubility had a negative effect on the Li⁺ extraction capacity, however. These results could provide key design elements for LTO anodes based on atomic level insights that can pave the way to an optimal protocol to achieve particular functionalities. Distorted lattice: Zr⁴⁺ is doped into a 1 D spinel Li₄Ti₅O₁₂ (LTO) nanostructure and the resulting electrochemical properties are explored through a combined theoretical and experimental investigation. The improved electrochemical performance resulting from incorporation of Zr⁴⁺ in the LTO is due to lattice distortion and, thereby, enlarged Li⁺ diffusion paths rather than to a change in the electronic structure.