In this study, we intend to revisit oxide/nanocarbon composites for a systematic study of oxide particle size, chemical bonding between oxide and carbon, electrical conductivity and ion transport in the composites on the electrochemical properties of NaTi2(PO4)3@nanocarbon microsphere composites prepared using zero-dimensional carbon black, one-dimensional carbon nanotubes, and two-dimensional graphene as anode materials for high-rate sodium-ion batteries. In the solution-based synthesis of the composites, oxide precursor nanoparticles deposited on nanocarbons are converted into final oxide nanoparticles through heat treatment. We demonstrate that growth of the NaTi2(PO4)3 particles in the NaTi2(PO4)3@nanocarbon composites occurs during heat treatment when the concentration of oxygen functional groups per unit specific area of nanocarbons is high. Growth of oxide precursor nanoparticles is observed for carbon black with a high concentration of oxygen functional groups during heat treatment owing to the proximity between precursor particles. On the other hand, growth of precursor nanoparticles is effectively prevented for carbon nanotubes and graphene with a low concentration of oxygen functional groups. Rate capability increases in the order of NaTi2(PO4)3@carbon black < NaTi2(PO4)3@graphene < NaTi2(PO4)3@carbon nanotubes mainly due to the smaller sizes of oxide particles and more efficient Na+ transport across carbon nanotubes compared to other nanocarbons.
Bibliographical noteFunding Information:
This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program ( 10062226 , development of flexible hybrid capacitor (0.25 mWh/cm2) composed of graphene-based flexible electrode and gel polymer electrolyte with high electrolyte uptake) funded By the Ministry of Trade, Industry & Energy (MOTIE, Korea) and a grant from Energy Technology Development Project (ETDP) funded by the Ministry of Trade, Industry & Energy ( 20172410100150 ).
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry