Improving Interface Stability of Si Anodes by Mg Coating in Li-Ion Batteries

Abstract

Silicon (Si) is a promising anode material for high-energy-density lithium-ion batteries (LIBs), but its short calendar life and poor cycling performance prevent its large-scale adoption. Introducing magnesium (Mg) salt into the electrolyte has been recently shown to form a ternary Li−Mg−Si Zintl phase upon lithiation of Si and improve the cycling performance. However, the ternary Zintl phase formation mechanism and its impact on the solid electrolyte interphase (SEI) are not yet well understood. Here, we demonstrate the formation of a ternary Li−Mg−Si Zintl phase by Mg coating of the Si anode, where Mg diffuses into the Si film upon deposition and intermixes further during the lithiation process. The presence of the Zintl phase improves the interface stability, alters the nature of the SEI, and enhances the cycling performance of the Si anode. This study provides insights into the formation mechanism of the ternary Zintl phase and guidelines for the future design of Si anodes.

The solvation structure, transport properties and reduction behavior of carbonate-based electrolytes of lithium-ion batteries

“…88,89 Moreover, it is reported that FEC exhibits a higher affinity towards the silicon surface than EC, and forms an ordered, up-right orientation, which may promote SEI formation and Li diffusion. 90,91 Most recently, artificial surface coating with the appropriate binder, 92 oxide layer, 93 and Mg metal 94 have been used to alter the interfacial interactions and reactions between the Si anode and electrolytes for achieving a stable SEI that minimizes side reactions and sustains efficient cycling. Finally, water contamination has been reportedly to causes detrimental parasitic reactions that affects the formation, evolution, and properties of the SEI.…”

Research Progress on Coating Structure of Silicon Anode Materials for Lithium‐Ion Batteries

“…It has been demonstrated that the electrochemical performance of silicon can be effectively improved by blocking the direct contact between silicon and electrolyte through surface coating modification. In addition to the coating of carbon materials, there are many other coating materials, such as metals, [105–112] metal silicide, [113–115] metal oxides, [116–127] metal sulfides, [37,128–134] silicon oxides, [135–145] and others [146–150] . The coating can exist in a tough or flexible form to buffer the volume expansion of silicon during cycling.…”

“…It was recently shown that the introduction of Mg salts can lead to the formation of ternary Li‐Mg‐Si Zintl phases during lithiation of Si, resulting in improved cycling performance. For a clearer understanding of the formation mechanism of ternary Zintl phase and its influence on SEI, Li et al [109] . prepared silicon thin films coated with magnesium layers as model electrodes (Figure 18a).…”

Synthesis of Si/Fe2O3-Anchored rGO Frameworks as High-Performance Anodes for Li-Ion Batteries

“…Table 1 displays the electrochemical performance of different Si-based electrode materials [26,28,[64][65][66][67][68][69][70]. The as-synthesized BM-SFG anode presents relatively excellent Li storage performance, which is better than that of many reported Si-based composites.…”