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

Abstract

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 ReO 3 -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 Nb 12 WO 33 structure that significantly enhances Li-ion storage performance compared to the known monoclinic Nb 12 WO 33 phase. The partially disordered phase consists of corner-shared NbO 6 octahedra blocks of varied sizes, including 5×4, 4×4, and 4×3, with a disordered arrangement of distorted WO 4 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.