TiNb₂O₇ microsphere anchored by polydopamine-modified graphene oxide as a superior anode material in lithium-ion batteries

TiNb₂O₇ (TNO) is considered a promising anode material for lithium-ion batteries. High contact and homogeneity of the composite fabricated by TNO powder and conductive materials with different density are significant to improve the poor electric conductivity of TNO microspheres. In this study, we introduce graphene oxide (GO) to synthesize a composite material with TNO microspheres. Moreover, a polydopamine (PDA) coating technique is applied to achieve uniform distribution and high contact between TNO and GO materials. The -OH catechol groups in the PDA have a strong adhesion ability to inorganic surfaces. After a simple sonication process, the hybrid material is well-fabricated, where TNO microspheres are attached along the surface of the PDA-coated GO (PGO). The TNO/PGO composite shows remarkably enhanced performances such as cycling stability (202.7 mAh g⁻¹ over 300 cycles at 1C) and rate capability (136.5 mAh g⁻¹ over 1000 cycles at 5C). The formation of a high conductive network among TNO microspheres mainly enhances those electrochemical performances, and the PDA layer is a key factor in obtaining a homogeneous GO composite through its high adhesive ability and hydrophilicity.