In situ synthesis of chemically bonded NaTi₂(PO₄)₃/rGO 2D nanocomposite for high-rate sodium-ion batteries

A phase-pure NaTi₂(PO₄)₃/reduced graphene oxide (rGO) nanocomposite was prepared using a microwave-assisted one-pot method and subsequent heat treatment. The well-crystallized NaTi₂(PO₄)₃ nanoparticles (30–40 nm) were uniformly precipitated on rGO templates through Ti–O–C bonds. The chemical interactions between the NaTi₂(PO₄)₃ nanoparticles and rGO could immobilize the NaTi₂(PO₄)₃ nanoparticles on the rGO sheets, which might be responsible for the excellent electrochemical performance of the nanocomposite. The NaTi₂(PO₄)₃/rGO nanocomposite exhibited a specific capacity of 128.6 mA·h·g^–1 approaching the theoretical value at a 0.1 C-rate with an excellent rate capability (72.9% capacity retention at 50 C-rate) and cycling performance (only 4.5% capacity loss after 1, 000 cycles at a high rate of 10 C). These properties were maintained even when the electrodes were prepared without the use of an additional conducting agent. The excellent sodium storage properties of the NaTi₂(PO₄)₃/rGO nanocomposite could be attributed to the nano-sized NaTi₂(PO₄)₃ particles, which significantly reduced the transport lengths for Na+ ions, and an intimate contact between the NaTi₂(PO₄)₃ particles and rGO due to chemical bonding.