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

Abstract 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.