A Disordered Crystallographic Shear Block Structure as Fast-Charging Anode Material for Lithium-Ion Batteries

A well-ordered structure with high crystallinity is crucial in various applications, particularly in electrode materials for batteries. The dimensionality and connectivity of the interstitial sites, determined by the crystal structure, inherently influence Li+ ions diffusion kinetics. Niobium tungsten oxides block structures, which are built by the assembly of ReO3-type blocks of specific sizes with metal sites having well defined positions within the crystalline structure, are promising fast-charging anode materials. Structural disorder generally disrupts the regular pathways for ion and electron movement, leading to lower overall conductivity. Here, we report a new anomalous disordered Nb12WO33 structure that significantly enhances the Li-ion storage performance compared to the known monoclinic Nb12WO33 phase. The disordered Nb12WO33 phase consists of corner-shared NbO6 octahedra blocks of varied sizes, including 5x4, 4x4, and 4x3, with a disordered arrangement of the tungsten tetrahedra at the corners of the blocks, as well as distortion of the WO4 tetrahedra. This structural arrangement is found to be extremely robust during lithiation/delithiation, leading to a topotactic local structure evolution during cycling, as determined by operando X-ray diffraction and X-ray absorption spectroscopy. It leads also to accelerated Li-ion migration within the disordered phase that results in excellent 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 valuable guidelines for designing materials with targeted properties.