Electrolytes for advanced lithium ion batteries using silicon-based anodes

Abstract

Recent progress in electrolytes from the liquid to the solid state for Si-based anodes is comprehensively summarized in this review article.

Si and Ge‐Based Anode Materials for Li‐, Na‐, and K‐Ion Batteries: A Perspective from Structure to Electrochemical Mechanism

“…Hence, an efficient approach to stabilize this SEI layer is the use of additives, which most of the times are designed to be consumed during the initial formation the SEI layer, but can serve also to improve the electrochemical stability window of the electrolyte, or to enhance the safety (flame retardants) . Common additives include vinyl carbonate (VC), fluoroethylene carbonate (FEC) or lithium bis(oxalate)borate (LiBOB) .…”

“…VC decomposes into polycarbonates at about 1 V versus Li/Li + , the presence of double bonds in its structure rend it is more susceptible to reduction . FEC decomposes at 1.3 V versus Li/Li + into a passivating layer that is much more compact resulting in a lower mass transfer resistance and improved capacity retention . FEC decomposes into polyenes and a high concentration of Li 2 O which prevents the diffusion of HF through the SEI .…”

“…FEC decomposes at 1.3 V versus Li/Li + into a passivating layer that is much more compact resulting in a lower mass transfer resistance and improved capacity retention . FEC decomposes into polyenes and a high concentration of Li 2 O which prevents the diffusion of HF through the SEI . It promotes the formation of LiF and SiF (Ge–F) bonds that are much stronger and give more stability to the SEI layer, compared to SiC (Ge–C) or SiO (Ge‐O) bonds that are constantly decomposing and reforming if there is no additive.…”

Safety Issues in Lithium Ion Batteries: Materials and Cell Design

“…The major components of the SEI layer is lithium salt (e.g., ROCO 2 Li, Li 2 CO 3 , and LiF) and polycarbonate (Chen et al, 2007). Electrolyte additive can leave their chemical signatures in the SEI layer which make it the most effective strategy to manipulate the targeted SEI property (Xu et al, 2019). Martin's group (Zeng et al, 2018) adopted FEC and VC as additives for nano Si electrode, and it was found that they can form a robust and thermal stable SEI that was rich in polycarbonates species which contribute to an enhanced thermal stability of the lithiated silicon electrode, thus increase the exothermic temperature by about 50 • C. Many other typical SEI-modifier additives, such as phosphorus (Mai et al, 2015;Song et al, 2016), nitrogen (Abu-Lebdeh and Davidson, 2009;Chen et al, 2016b), boron (Lee et al, 2014b;Kim et al, 2017), sulfur (Zuo et al, 2014), or silicon containing species (Chen et al, 2017b;Wang et al, 2017a), are widely studied in thermal stability enhancement of both SEI and CEI, some dual-functionalgroup additives, such as N,N-diallyic-diethyoxyl phosphamide (DADEPA) (Cao et al, 2013), tris(trimethylsilyl)phosphate (TMSP) (Rong et al, 2014), tris(trimethylsilyl)borate (TMSB) (Liu et al, 2013) are also intensively studied.…”

Silicon Anodes for High‐Performance Storage Devices: Structural Design, Material Compounding, Advances in Electrolytes and Binders

“…The pulverization of silicon particles makes the Coulombic efficiency low in the first circle, and it is difficult to maintain good cycle stability . A uniform carbon coating prevents direct contact between the silicon particles and the electrolyte, promoting stable solid electrolyte layer formation . It has the most stable solid‐electrolyte interface (SEI) formed at the cracks .…”