Ferroelectric-Polarization-Driven Structural Engineering of Bi₃Nb₁₇O₄₇ Anodes for High-Performance Lithium-Ion...

Metal-ion batteries face challenges in optimizing electrode materials to enhance capacities and structural stability. Traditional strategies like defect engineering and elemental doping show limitations, necessitating innovative approaches. Herein, we propose a ferroelectric-polarization strategy to modulate the crystal structure of Bi₃Nb₁₇O₄₇, a tungsten bronze (TTB)-type anode material with a theoretical capacity of 308 mAh g^-1 but restricted Li⁺ storage sites. The polarization induces asymmetric displacements of Nb⁵⁺ and inward contraction of O^2-, enlarging the Li⁺-storage cavities by approximately 8%. This structural tailoring significantly boosts the reversible capacities of Bi₃Nb₁₇O₄₇ by 36%-55% across various current densities (0.1-10 C). Furthermore, the enlarged Li⁺-storage cavities enable smaller unit-cell-volume fluctuations, resulting in its enhanced cycling stability (84.9% capacity retention after 1000 cycles at 5 C). This work pioneers electric-field-driven structural engineering in electrochemical energy-storage materials, offering a transformative modification strategy for high-performance metal-ion batteries.