Improving the electrochemical performance of Si nanoparticle anode material by synergistic strategies of polydopamine and graphene oxide coatings

(Chemical Equation Presented). Graphene oxide/polydopamine-coated Si nanocomposite (GO/PDA-Si) was synthesized by a novel facile solution-based chemical method at room temperature. The nanocomposite with a PDA coating layer of ∼1.5 nm exhibits a high reversible specific capacity and excellent cycling stability (1074 mAh g^-1 after 300 cycles at 2100 mA g^-1) as an anode material for lithium ion batteries. The synergistic effect of the PDA coating layer and GO plays an important role in improving the electrochemical lithium storage performances. Both of them can serve as a cushion to buffer the volume change of Si nanoparticles (NPs) during the charge/discharge process and prevent Si NPs from direct contact with a liquid electrolyte. The surface property of Si NPs was also modified by introducing secondary amine groups, which can form amide groups with carboxyl groups and hydrogen bonds with hydroxyl/carboxyl groups on GO. These chemical interactions firmly anchor Si NPs to GO so that aggregation of Si NPs can be mostly prevented. Moreover, the good lithium ion conductivity of PDA is beneficial for rate performance. The experimental results should be very useful in guiding the preparation of long-cycle-life Si-based anode materials with good rate performance using a simple surface-modifi cation process.