Interface Chemistry Engineering of Protein‐Directed SnO 2 Nanocrystal‐Based Anode for Lithium‐Ion Batteries with Improved Performance

A novel uniform amorphous carbon‐coated SnO 2 nanocrystal (NCs) for use in lithium‐ion batteries is formed by utilizing bovine serum albumin (BSA) as both the ligand and carbon source. The SnO 2 –carbon composite is then coated by a controlled thickness of polydopamine (PD) layer through in situ polymerization of dopamine. The PD‐coated SnO 2 –carbon composite is finally mixed with polyacrylic acid (PAA) which is used as binder to accomplish a whole anode system. A crosslink reaction is built between PAA and PD through formation of amide bonds to produce a robust network in the anode system. As a result, the designed electrode exhibits improved reversible capacity of 648 mAh/g at a current density of 100 mA/g after 100 cycles, and an enhanced rate performance of 875, 745, 639, and 523 mAh/g at current densities of 50, 100, 250, and 500 mA/g, respectively. FTIR spectra confirm the formation of crosslink reaction and the stability of the robust network during long‐term cycling. The great improvement of capacity and rate performance achieved in this anode system is attributed to two stable interfaces built between the active material (SnO 2 –carbon composite) and the buffer layer (PD) and between the buffer layer and the binder (PAA), which effectively diminish the volume change of SnO 2 during charge/discharge process and provide a stable matrix for active materials.