Highly conductive graphene-modified TiO2 hierarchical film electrode for flexible Li-ion battery anode.

Flexible Li-ion batteries have shown great promise in powering wearable electronic devices due to their high energy/power densities and long cycling time. However, coordinating the promising electrochemical performance and flexibility for different applications is still a big challenge. Herein, we report a highly conductive graphene-modified mesoporous anatase TiO 2 (M-TiO 2 -GS) hierarchical film electrode for flexible Li-ion battery anode via a two-step vacuum filtration method. In such a hierarchical film electrode, the down-layer composed of bare graphene component provides ideal mechanical flexibility and electronic conductivity, and the hybrid top-layer composed of both graphene and active M-TiO 2 guarantees effective Li+ and electrons transport pathways and acts as the active layer for energy storage. The designed M-TiO 2 -GS film electrode delivers a reversible capacity of 205 and 76 mAh g−1 at rates of 0.5C and 20C, respectively, and high capacity retention of ∼70.5% after 3500 cycles at 5C. When packed in flexible cells, the M-TiO 2 -GS electrode can also maintain a highly reversible capacity and outstanding cycling stability in both flating and benting conditions. This work may provide a promising anode candidate for the next-generation flexible LIBs and the developed two-step filtration method can be readily applied to other flexible electrodes. Less defective graphene nanosheets with relatively high conductivity have been employed to fabricate a free-standing flexible M-TiO 2 -GS anode for LIBs through a two-step vacuum filtration method. Layer-by-layer assembled GS networks connected with M-TiO 2 cakes provides criss-crossed fast electrons transport paths and available ions diffusion channels, leading to great Li+ storage behavior. Image 1 • Highlights to Electrochimica Acta . • A graphene-modified TiO 2 hierarchical flexible film electrode is designed. • The designed film electrode has optimized electrochemical kinetic properties. • The electrode shows excellent performance in both free and bending conditions. [ABSTRACT FROM AUTHOR]