Electrolytic receiving silicon nanowires from KCl-KF-K2SiF6-SiO2 fusion as composite anodes for lithium-ion batteries

Abstract

Silicon nano- and microwires have been obtained by KCl-KF-K2SiF6-SiO2 melt electrolysis in air; this material is suitable as anode component for lithium ion batteries. Optimal conditions of electrolysis were determined. Morphology, phase and chemical composition of silicon deposits were established. Electrochemical behavior of silicon nanowires as anode component was evaluated using solid polymer electrolyte cells.

Electrodeposition of Thin Silicon Films from the KF-KCl-KI-K2SiF6 Melt

“…[4][5][6][8][9][10][11] Electrodeposition from molten salts is a promising method for the production of silicon nanowires and thin silicon films on various substrates. [12][13][14][15][16][17][18][19] This method allows controlling the deposits structure and morphology as well as achieving significant rates of the new phase growth. The KF-KCl-K 2 SiF 6 melt is a suitable electrolyte for the silicon electrodeposition, because it provides a stable silicon concentration, it is water-soluble and less aggressive than a purely fluoride electrolyte.…”

Silicon Electrodeposition for Microelectronics and Distributed Energy: A Mini-Review

“…To date, the greatest attention has been paid to the targeted production of silicon for energy conversion and storage devices, mainly from molten CaCl2-(NaCl)-CaO-SiO2 (CaSiO3) [26][27][28] and KF-KCl-K2SiF6 [29][30][31] with operating temperatures of 800-860 and 700-750 °C, respectively (see Table 1). The disadvantages of chloride-oxide melt are its relatively high temperature, low rates of silicon electrodeposition, and the presence of oxides in the melt.…”

“…In turn, the disadvantage of the fluoridechloride system is its relatively high chemical activity, which leads to corrosion of the structural materials of the reactor and complicates the production of high-purity silicon. Despite disadvantages, researchers [26][27][28][29][30][31] have reported silicon deposits obtained by electrolysis of CaCl2-CaO and KF-KCl-based melts in the form of fibers (from 30 to 500 nm), dendrites, thin films, and other morphologies. The declared purity of electrolytically obtained silicon reaches 99.99 wt% or more if the impurities of the electrolyte components are not taken into account [28].…”

“…The results of tests involving a lithium-ion current source of silicon electrodeposited from KF-KCl-K2SiF6-based melts are extremely limited. In particular, nanosized silicon particles (25-50 nm) and fibers (diameter 150-250 nm, length 1-4 μm) with a specific surface area of 14-15 m 2 g −1 were obtained [31] at a temperature of 700°C and a cathode current density of 10-20 mA cm −2 . The principal possibility of lithiation or delithiation of the obtained silicon was demonstrated.…”

Electrodeposition of Silicon from Molten KCl-K2SiF6 for Lithium-Ion Batteries

“…18,19 Although nanostructured materials show better performance, in recent years there has been a reverse trend towards the transition from expensive nanomaterials to micro-sized ones. 20,21 Currently, many methods of silicon synthesis [22][23][24][25][26] and surface modification have been proposed. [27][28][29] Methods of silicon synthesis are magnesiothermic reduction of silica, 25 chemical vapor deposition, 30,31 molecular beam epitaxy, 32 electrodeposition 22 and some other not so commonly used methods like arc plasma reactor, 23 capacitive plasma discharge 24 physical vacuum distillation 26 etc.…”