Size-tunable SnS2 nanoparticles assembled on graphene as anodes for high performance lithium/sodium-ion batteries.

• Size-tunable SnS 2 /RGO make facile study the effect of particle size on Li/Na storage. • Ions diffusion coefficient, surface and diffusion capacitive contribution are studied. • Small-sized particle promotes charge/ion transfer and pseudocapacitor contribution. • Controllable dimension promotes fast kinetics for high rate materials. Controlling the particle sizes of electrode materials has long been recognized as an effective way to improve the cycle stability and rate property of both lithium-ion battery (LIB) and sodium-ion battery (SIB). In this paper, a simple one-step hydrothermal process for the preparation of composites with size-tunable tin disulfide on reduced graphene oxide (SnS 2 /RGO) is reported. These novel material allow to comprehensively study the effect of particle sizes on electrochemical properties for LIB and SIB anodes. The structure, morphology, phase compositions, and Li+/Na+ storage behaviors of three different SnS 2 /RGO composites obtained at heat-treatment times of 12, 24 and 48 h are characterized systematically. The electrochemical reaction kinetics is demonstrated by differential charge capacity plots and apparent ion diffusion coefficients. Surface capacitive and diffusion-controlled capacitive contributions to lithium/sodium ions storage are also compared. The results show that the small-sized nanoarchitecture can promote both the charge and ions transfer and thus improve the pseudocapacitor contribution. The reversible capacity maintains at 1211 mAh g−1 for LIB after 200 cycles and 841 mAh g−1 for SIB after 100 cycles, respectively, which is superior to most of the previous reports. This work is expected to provide a profound understanding of composite anodes with controllable dimensions and fast kinetics. The effect of SnS 2 nanoparticle size on the Li and Na storage characteristics of SnS 2 /RGO composite anodes are compared, it show that the decreased particle size promotes the pseudocapacitor contribution, as well as the reversed conversion reaction and structural stability. Image, graphical abstract [ABSTRACT FROM AUTHOR]