Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C (PC) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC anode consisting of 50 wt % Sn and 50 wt % PC, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g with a discharge capacity of 834.25 mAh g. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g at a high current density of 10 000 mA g, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g. Futhermore, a SPC-50 full-cell containing the LiCoO cathode exhibited a discharge capacity of 801.04 mAh g and an areal capacity of 1.57 mAh cm with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g.
Lithium-ion capacitors (LICs) and lithium-ion batteries (LIBs) are important energy storage devices. As a material with good mechanical, thermal, and chemical properties, low-carbon silicon oxycarbide (LC-SiOC), a kind of silicone oil-derived SiOC, is of interest as an anode material, and we have examined the electrochemical behavior of LC-SiOC in LIB and LIC devices. We found that the lithium storage mechanism in LC-SiOC, prepared by pyrolysis of phenyl-rich silicon oil, depends on an oxygen-driven rather than a carbon-driven mechanism within our experimental scope. An investigation of the electrochemical performance of LC-SiOC in half- and full-cell LIBs revealed that LC-SiOC might not be suitable for full-cell LIBs because it has a lower capacity (238 mAh g) than that of graphite (290 mAh g) in a cutoff voltage range of 0-1 V versus Li/Li, as well as a substantial irreversible capacity. Surprisingly, LC-SiOC acts as a pseudocapacitive material when it is tested in a half-cell configuration within a narrow cutoff voltage range of 0-1 V versus Li/Li. Further investigation of a "hybrid" supercapacitor, also known as an LIC, in which LC-SiOC is coupled with an activated carbon electrode, demonstrated that a power density of 156 000 W kg could be achieved while maintaining an energy density of 25 Wh kg. In addition, the resulting capacitor had an excellent cycle life, holding ∼90% of its energy density even after 75 000 cycles. Thus, LC-SiOC is a promising active material for LICs in applications such as heavy-duty electric vehicles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.