N-doped carbon layer derived from polydopamine to improve the electrochemical performance of spray-dried Si/graphite composite anode material for lithium ion batteries

Abstract To improve the electrochemical performance of silicon-based anode, silicon/carbon (Si/C) material was synthesized via dopamine polymerization process and subsequent pyrolysis. The carbonized polydopamine (PDA-C) is N-doped, which improves the electronic conductivity of material and helps lithium ion transmission. The existence of polydopamine-derived carbon is evidenced by X-ray photoelectron spectroscopy and scanning electron microscopy. Electrochemical characterizations confirms that the composite with PDA-C layer exhibits initial reversible specific capacity of 741.2 mAh g −1 with an initial coulombic efficiency of 78.1% at current density of 300 mA g −1 . A high capacity of 611.3 mAh g −1 can be delivered for composite with PDA-C layer after 100 cycles at a current density of 300 mA g −1 . The rate capability is also enhanced, delivering reversible capacity of 704.3, 611.4, 529.3, 480.3 mAh g −1 at current densities of 1, 2, 3, 4 A g −1 .