The role of electrolyte additives on the interfacial chemistry and thermal reactivity of Si-Anode based Li-ion battery

Aupperle F, von Aspern N, Berghus D, Weber F, Eshtu GG, Winter M, Figgemeier E

Research article (journal)

Abstract

Silicon (Si) has gained huge attention as an anode material for next-generation high-capacity lithium-ion batteries (LIBs). However, despite its overwhelming beneficial features, its large-scale commercialization is hampered due to unavoidable challenges such as colossal volume change during (de-)alloying, inherent low electronic and ionic conductivities, low Coulombic efficiency, unstable/dynamic solid electrolyte interphase (SEI), electrolyte drying etc. Among other strategies, the use of a fraction dose of chemical additives is hailed as the most effective, economic and scalable approach to realize Si-anode based LIBs. Functional additives can modify the nature and chemical composition of the SEI, which in turn dictates the obtainable capacity, rate capability, Coulombic/energy efficiency, safety etc of the battery system. Thus, we report a systematic and comparative investigation of various electrolyte additives, namely tetraethoxysilane (TEOS), (2-Cyanoethyl)triethoxysilane (TEOSCN), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and a blend of TEOSCN, VC and FEC (i.e. VC/FEC/TEOSCN) using electrochemical analysis, X-ray photoelectron spectroscopy (XPS), Density Functional Theory (DFT), calculation and differential scanning calorimetry (DSC). The ternary mixture (FEC/VC/TEOSCN) results in a thinner SEI layer consisting of high shear modulus SEI-building species (mainly LiF). It also provides much improved thermal stability amid all tested additives, evidencing its potentiality to enable high capacity and safer Si anode-based LIBs. Thus, nitrile-functionalized silanes are highly promising electrolyte additives to boost the electrochemical performance and safety-induced risks of Si anode-based LIBs, emanating from the formation of a robust SEI layer.

Details zur Publikation

Release year: 2019
Language in which the publication is written: English