SnSex (x=1, 2) nanoparticles encapsulated in carbon nanospheres with reversible electrochemical behaviors for lithium-ion half/full cells

Tin selenide materials, including SnSe and SnSe2, have larger interlayer spacing, weaker van der Waals forces still suffer undesirable volume changes as lithium-ion battery anodes. Herein, we successfully synthesized hierarchical SnSex (x = 1, 2) nanoparticles encapsulated in carbon nanospheres (SnSex & SUB; CNSs) by facile in-situ selenation method at different temperature. Partially diffused SnSex nanoparticles form halo surrounding the SnSex core with spare inner void space, coupled with thin carbon layer could enhance ionic transport and buffer volume expansion of SnSex in Li+ insertion/desertion processes. The SnSe & SUB; CNSs and SnSe2 & SUB; CNSs anodes all deliver high initial coulombic efficiency, superior cycle stability and excellent rate capability. SnSe & SUB; CNSs// LiMn2O4 and SnSe2 & SUB; CNSs//LiMn2O4 full cells also exhibit outstanding electrochemical properties. Further-more, ex-situ X-ray diffraction patterns demonstrate the detailed reaction mechanisms and confirm the reversible conversions of SnSe & SUB; CNSs and SnSe2 & SUB; CNSs. The comparison of dynamic behaviors of them by electrochemical impedance spectroscopy and cyclic voltammetry at different cycles confirm the existence of more intermediate Li2Se in SnSe2 & SUB; CNSs, which could enhance the ion kinetics and improve rate capability. Thus, lower synthesis temperature, lower Li+ migration energy barrier, outstanding electrochemical performance, and higher excellent ion kinetics of SnSe2 & SUB; CNSs suggest that our synthesized SnSe2 & SUB; CNSs are more suitable as LIB anodes to in-crease the energy density.

Automated summary

Hierarchical SnSex (x = 1, 2) nanoparticles encapsulated in carbon nanospheres (SnSex & SUB; CNSs) were successfully synthesized, which exhibited excellent electrochemical performance and rate capability. Experimental results and analysis confirmed their superior cycle stability and ion kinetics.