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.