Self-assembly engineering toward large-area defect-rich TiO2(B) nanosheets-based free-standing films for high-performance lithium-ion batteries

Nanosheets with large exposed surface and high chemical activity are of paramount significance for catalysis, gas sensing and energy storage. However, assembling them into large-area free-standing films and preventing aggregation of individual nanosheets remain a great challenge. Herein, an efficient strategy is proposed to assemble defect-rich TiO2(B) nanosheets into a 3D-scaffold structured free-standing film, which can preserve high chemical activity and prevent their aggregation. The inherent pores of Teflon lining are employed as load-bearing base to construct 3D scaffolds, and then, a rapid dissolution-recrystallization hydrothermal process is developed to fabricate defect-rich TiO2(B) nanosheets (~5 nm in thickness) on the 3D scaffolds. The numerous defects are crucial for boosting high rate performance within LIBs. The hierarchical 3D-scaffold structure endows the nanosheets-based electrode with outstanding cycling stability (96.1% retention after 6000 cycles at 6.7 A g−1), which hits a record high in terms of capacity retention for TiO2(B) nanosheets at high rate. The strategy for fabricating and assembling defect-rich TiO2(B) nanosheets paves the way for high performance LIBs.