S-containing and Si-containing compounds as highly effective electrolyte additives for SiO_x -based anodes/NCM 811 cathodes in lithium ion cells.

ABSTRACT: Recently, high-energy density cells containing nickel-rich cathodes and silicon-based anodes have become a practical solution for increasing the driving range of electric vehicles. However, their long-term durability and storage performance is comparatively poor because of the unstable cathode-electrolyte-interphase (CEI) of the high-reactivity cathode and the continuous solid-electrolyte-interphase (SEI) growth. In this work, we study several electrolyte systems consisting of various additives, such as S-containing (1,3,2-dioxathiolane 2,2-dioxide (DTD), DTD?+?prop-1-ene-1,3-sultone (PES), methylene methanedisulfonate (MMDS)) and Si-containing (tris(trimethylsilyl) phosphate (TTSP) and tris(trimethylsilyl) borate (TMSB)) compounds, in comparison to the baseline electrolyte (BL?=?1.0?M LiPF₆?+?3:5:2 w-w:w EC: EMC: DEC?+?0.5?wt% lithium difluoro(oxalato)borate (LiDFOB)?+?2?wt% lithium bis(fluorosulfonyl)imide (LiFSI)?+?2?wt% fluoroethylene carbonate (FEC)?+?1?wt% 1,3-propane sultone (PS)). Generally, electrolytes with Si-containing additives, particularly BL?+?0.5% TTSP, show a lower impedance increase in the full cell, better beginning-of-life (BOL) performance, less reversible capacity loss through long-term cycles and better storage at elevated temperatures than do electrolytes with S-containing additives. On the contrary, electrolytes with S-containing additives exhibit the advantage of low SEI impedance but yield a worse performance in the full cell than do those with Si-containing additives. The difference between two types of additives is attributed to the distinct function of the electrodes, which is characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS), which was performed on full cells and half cells with fresh and harvested electrodes.

SUBMITTER: An F 

PROVIDER: S-EPMC6773705 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature