Monolithic Microparticles Facilitated Flower-Like TiO₂ Nanowires for High Areal Capacity Flexible Li-Ion Batteries

Flexible lithium-ion batteries (FLIBs) are intensively studied using free-standing transition metal oxides (TMOs)-based anode materials. However, achieving high areal capacity TMO-based anode materials is yet to be effectively elucidated owing to the poor adhesion of the active materials to the flexible substrate resulting in low active mass loading, and hence low areal capacity is realized. Herein, a novel monolithic rutile TiO₂ microparticles on carbon cloth (ATO/CC) that facilitate the flower-like arrangement of TiO₂ nanowires (denoted ATO/CC/OTO) is demonstrated as high areal capacity anode for FLIBs. The optimized ATO/CC/OTO anode exhibits high areal capacity (5.02 mAh cm^-2@0.4 mA cm^-2) excellent rate capability (1.17 mAh cm^-2@5.0 mA cm^-2) and remarkable cyclic stability (over 500 cycles). A series of morphological, kinetic, electrochemical, in situ Raman, and theoretical analyses reveal that the rational phase boundaries between the microparticles and nanowires contribute to promoting the Li storage activity. Furthermore, a 16.0 cm² all-FLIB pouch cell assembled based on the ATO/CC/OTO anode and LiNiCoMnO₂ cathode coated on ATO/CC (ATO/CC/LNCM) exhibits impressive flexibility under different folding conditions, creating opportunity for the development of high areal capacity anodes in future flexible energy storage devices.