Toward stable lithium-ion batteries: Accelerating the transfer and alloying reactions of Sn-based anodes via coordination atom regulation and carbon hybridization

Abstract

Although anodes based on Sn alloys (SnX) such as SnO2, SnS, and Sn4P3 may be used to increase the gravimetric and volumetric energy densities of existing lithium-ion batteries, the further development of these anodes is hindered by their complex reaction mechanisms, sluggish conversion, and the occurrence of undesired reactions. Herein, we probe the mechanisms of the incompletely reversible reactions of SnO2 and SnS using analytical and electrochemical techniques and demonstrate that the capacity retention of these species can be further increased using coordination atom regulation and hybridization with carbon. The superior cyclability (sustainable operation for >500 cycles) of the optimized SnS/C composite is attributed to its reinforced conversion and alloying reactions resulting from enhanced bulk structure, higher interface stability, and accelerated kinetics. This work also provides guidance for the development of other alloy-based anode materials, especially regarding the choice of coordination atoms and the understanding of the role of carbon coatings in property optimization.