ABSTRACT
This paper reports a fast and efficient excimer ultraviolet (EUV) radiation method to prepare carbon-coated mixed tin oxide-loaded exfoliated graphite (SnOx@C-G) nanocomposites. The SnOx small nanoparticles (SNPs) are isolated using oxidized sucrose and uniformly deposited onto mildly oxidized exfoliated graphite during the 20-minute EUV radiation process. XPS and ESR analyses suggest the existence of abundant oxygen vacancies in the SnOx SNPs. The electrochemical kinetics of SnOx@C-G, which are determined by in situ electrochemical impedance analysis, demonstrated a high reversible capacity of approximately 740 mA h g-1 after 250 cycles at a current density of 1.6 A g-1, and an impressive reversible rate performance exceeding 450 mA h g-1 can be obtained even at a high current density of 3.2 A g-1 when applied as an anode for lithium storage. This improved cycling stability and rate capability benefit from the carbon coating, which not only buffers the volume change of SnOx SNPs but also provides a path for electron transport on the surface of the SnOx SNPs during the electrochemical process. Furthermore, the oxygen vacancies in SnOx SNPs result in a large capacitive contribution to capacity. The EUV radiation method used to synthesize SnOx@C-graphite nanosheets is universally applicable to prepare a high-performance SNPs/carbon-based anode for lithium-ion batteries.
ABSTRACT
Carbon nanofibers (CNFs) bearing oxygen-containing functional groups and inhomogeneous nanopores are successfully prepared by excimer UV radiation. The CNFs demonstrate potential for use as an anodic material in rechargeable Li-ion batteries. Their improved electrochemical performances are attributed to the chemically bonded solid-electrolyte interface films on the CNF surface. This approach is also applicable to other carbonaceous electrode materials.