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.

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Coal gangue is a solid waste discharged during coal mining, which not only occupies large land resources but also brings about certain risks to the environment. The alumina and silica minerals in coal gangue are the major resources and difficult to separate from each other, which hinders the resource utilization of coal gangue. The catalytic effect of various additives on the phase transformation process of coal gangue is studied in this paper to strengthen the separation of silica from alumina minerals and to increase the resource utilization rate of coal gangue. The study results show that the silica-containing minerals in coal gangue can be promoted to transform into mullite by alumina-based additives. The soluble active silica is released during phase transformation in the calcination process, which has a positive effect on the caustic desilication after calcination. The secondary aluminum dross has a positive catalytic effect on the active silica released during calcination. The alumina to silica ratio of the desilication product can be increased from 0.91 to 1.94 and the desilication rate can be increased from 42.99 to 56.16% by 6% secondary aluminum dross addition. The solid slag after desilication can be used to extract an alumina source for the synthesis of molecular sieve products with the silica source obtained by the desilication process so that the high-value resource utilization of coal gangue can be realized.