A partially disordered crystallographic shear block structure as fast-charging negative electrode material for lithium-ion batteries.

Abstract

A well-ordered crystalline structure is crucial in battery electrodes, as the dimensionality and connectivity of the interstitial sites inherently influence Li⁺ ions diffusion kinetics. Niobium tungsten oxides block structures, composed of ReO₃-type blocks of specific sizes with well-defined metal sites, are promising fast-charging negative electrode materials. Structural disorder is generally detrimental to conductivity or ion transport. However, here, we report an anomalous partially disordered Nb₁₂WO₃₃ structure that significantly enhances Li-ion storage performance compared to the known monoclinic Nb₁₂WO₃₃ phase. The partially disordered phase consists of corner-shared NbO₆ octahedra blocks of varied sizes, including 5×4, 4×4, and 4×3, with a disordered arrangement of distorted WO₄ tetrahedra at the corners of the blocks. This structural arrangement is robust during lithiation/delithiation, exhibiting minor local structure changes during cycling. It enables accelerated Li-ion migration, resulting in promising fast-charging performance, namely, 62.5 % and 44.7 % capacity retention at 20 C and 80 C, respectively. This study highlights the benefits of introducing disorder into niobium tungsten oxide shear structures, through the establishment of clear structure-performance correlations, offering guidelines for designing materials with targeted properties.