Sn@C evolution from yolk-shell to core-shell in carbon nanofibers with suppressed degradation of lithium storage

Abstract

Metallic Sn has high conductivity and high theoretical capacity for lithium storage but it suffers from severe volume change in lithiation/delithiation leading to capacity fade. Yolk-shell and core-shell Sn@C spheres interconnected by carbon nanofibers were synthesized by thermal vapor and thermal melting of electrospun nanofibers to improve the cycling stability. Sn particles in yolk-shell spheres undergo dynamic structure evolution during thermal melting to form coreshell spheres. The core-shell spheres linked along the carbon nanofibers show outstanding performance and are better than the yolk-shell system for lithium storage, with a high capacity retention of 91.8% after 1000 cycles at 1 A g-1. The superior structure of core-shell spheres interconnected by carbon nanofibers has facile electron conductivity and short lithium ion diffusion pathways through the carbon nanofibers and shells, and redevelops Sn@C structures with Sn clusters embedded into carbon matrix during electrochemical cycling, enabling the high performance.

Highly sensitive thermoelectric touch sensor based on p-type SnO x thin film

“…Using the Van der Pauw configuration we measure the σ of 4.1×10 2 ±0.9 S m −1 and 6.9×10 2 ±0.5 S m −1 for the 60 nm-SnO x and 90 nm SnO x films, which results in a PF value of 29.7±1.1 μW m −1 K −2 and 8.7±0.2 μW m −1 K −2 , respectively. A metallic behavior is observed for the thicker film, with ρ=12×10 −7 Ω m, typical of metallic Sn (1.1×10 −7 Ω m at room temperature [32]). The measured electrical conductivity values for thinner SnO x films are higher when compared to the values previously published for the tin oxide materials (SnO and SnO 2 ) [6,16,30,33].…”

In Situ Derivatization for Boosted Lithium Storage Performance of Fe7S8/C Hollow Nanospheres

“…The peak strength ratio of D band and G band of Fe 7 S 8 /C HNSs is 0.83 lower than that of Fe(PO 3 ) 2 /Fe 2 O 3 /C (1.25) and Fe 3 O 4 (0.86). It indicates that the graphitization degree of carbon shell layer in Fe 7 S 8 /C HNSs is higher, which is good for improving the conductivity of composite …”

“…It indicates that the graphitization degree of carbon shell layer in Fe 7 S 8 /C HNSs is higher, which is good for improving the conductivity of composite. [22] From Figure 6(a), there is one obvious weight loss stage in the thermogravimetric curve of Fe 7 S 8 /C HNSs. The only weight loss stage from 30 to 900°C is attributed to the decomposition of carbon shell in Fe 7 S 8 /C HNSs and the oxidation of Fe 7 S 8 and the mass loss rate is as high as 56.90%.…”

Carbon-containing electrospun nanofibers for lithium–sulfur battery: Current status and future directions

“…The basic principle of electrospinning is based on the uniaxial elongation of electrospinning solution that consists of organic polymer and corresponding solvent. Organic polymers include polyacrylonitrile (PAN) [40,[59][60][61], poly(vinylidene fluoride) (PVDF) [62], poly (methyl methacrylate) (PMMA) [63][64][65], poly (vinyl pyrrolidone) (PVP) [63,65,66], poly (vinyl alcohol) (PVA) [67][68][69], polyimide (PI) [70], polytetrafluoroethylene (PTFE) [71], polystyrene (PS) [72] or mixtures of the above polymers. These organic polymers are generally dissolved in one or more solvents, such as N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), ethanol (EtOH), mineral oil or water.…”