Growth Temperature of Integrated 2D SnS Microrods with Sulfur Vacancies Enabling Ultrahigh Power Na-Ion Microbatteries

Abstract “Microbatteries” are known to be the key to device miniaturization, but the practicality associated with one such domain of SnS thin films in Na-ion microbatteries (Na-μBs) is limited by slow Na+ kinetics and cycling-induced pulverization. These issues are strongly affected by microstructure, crystallinity, and interface quality, which can be tuned through growth temperature; however, their correlation with electrochemical performance remains unclear. Herein, SnS thin films with a thickness of 86.76 ± 4 nm were prepared via hydrothermal-assisted thermal evaporation at varying growth substrate temperatures. The optimal film growth occurs at 200 °C under sulfur-deficient conditions, yielding a high areal discharge capacity of 55 μAh/cm2 at a high current density of 200 μA/cm2 and remarkable retention of 88.6% over 150 cycles. The CV and DFT analyses reveal the capacitive–diffusive kinetics and charge localization around sulfur in SnS, facilitating Na–S bonds in conversion alloying reactions. Furthermore, demonstrations of powering LEDs highlight the practical applicability of SnS thin films as anodes in Na-μBs.