Tailoring Stress and Ion-Transport Kinetics via a Molecular Layer Deposition-Induced Artificial Solid Electrolyte Interphase for Durable Silicon Composite Anodes

Abstract

Silicon is considered as a blooming candidate material for next-generation lithium-ion batteries due to its low electrochemical potential and high theoretical capacity. However, its commercialization has been impeded by the poor cycling issue associated with severe volume changes (∼380%) upon (de)­lithiation. Herein, an organic–inorganic hybrid film of titanicone via molecular layer deposition (MLD) is proposed as an artificial solid electrolyte interphase (SEI) layer for Si anodes. This rigid-soft titanicone coating with Young’s modulus of 21 GPa can effectively relieve stress concentration during the lithiation process, guaranteeing the stability of the mechanical structure of a Si nanoparticles (NPs)@titanicone electrode. Benefiting from the long-strand (Ti–O–benzene–O–Ti−) unit design, the optimized Si NPs@70 cycle titanicone anode delivers a high Li+ diffusion coefficient and a low Li+ diffusion barrier, as revealed by galvanostatic intermittent titration (GITT) investigations and density functional theory (DFT) simulations, respectively. Ultimately, the Si NPs@70 cycle titanicone electrode shows high initial Coulombic efficiency (84%), long cycling stability (957 mAh g–1 after 450 cycles at 1 A g–1), a stable SEI layer, and good rate performances. The molecular-scale design of the titanicone-protected Si anodes may bring in new opportunities to realize the next-generation lithium-ion batteries as well as other rechargeable batteries.

Dual‐Design of Nanoporous to Compact Interface via Atomic/Molecular Layer Deposition Enabling a Long‐Life Silicon Anode

“…To the best of our knowledge, such high-level cyclability of zincone/TiO 2 coated anode outperforms the most reported silicon-based anode materials for LIBs to date (Figure 4h), and is superior to that of the phase-pure TiO 2 , zincone or titanicone film modified silicon electrodes. [15,16,19,21,27] To assess the structural stability, the volume and morphological changes of the four electrodes are scrutinized in Figure 5; Figure S9, Supporting Information. In contrast to the pure Si electrode, Si@zincone/TiO 2 electrode shows overall integrity and flatness after five cycles from the digital photos (The insets in Figure S9, Supporting Information).…”

“…The atomic force microscopy (AFM) image ( Figure a) of zincone film and the corresponding height profiles (Figure 3b) show that the depth of two half pores of zincone film are ≈5.2 nm and 3.7 nm, whereas in the region without pore, the zincone film exhibits admirable flatness similar to that of titanicone film. [ 21 ] A lateral radius distribution in the range of 2–25 nm is observed from the digital image processing, and the statistical average pore radius is ≈9 nm (Figure 3c). And based on our previous study, the porosity of zincone coating is ≈53% measured by ellipsometric porosimetry (EP).…”

“…To the best of our knowledge, such high‐level cyclability of zincone/TiO 2 coated anode outperforms the most reported silicon‐based anode materials for LIBs to date (Figure 4h), and is superior to that of the phase‐pure TiO 2 , zincone or titanicone film modified silicon electrodes. [ 15,16,19,21,27 ]…”

“…A titanicone coating, made by alternatively dosing TiCl 4 and hydroquinone (HQ), has been shown to be effective at dissipating inner stress during (de)lithiation and suppressing the excessive growth of SEI. [ 21 ] Sun's groups have studied the effect of zincone on silicon electrodes for LIBs, zincone‐derivatives (metallic zinc and organic polymer) and dominant LiF during cycling buffer the volume changes and thus improve cyclability. [ 16 ] Nevertheless, the currently established MLD films for long‐life Si‐based anodes are still insufficient, the cycle number of currently reported MLD coated silicon electrode is almost less than 600.…”

Atomic/Molecular Layer Deposition for Designer's Functional Metal–Organic Materials

“…[117,229] For titanium, the most common precursor is TiCl 4 , extensively used with EG, [179,293,[391][392][393][394][395][396][397][398][399][400] and other orga nics. [46,49,105,112,122,211,230,232,235,248,254,255,336,378,390,[401][402][403][404][405][406][407][408] For example, the combination, TiCl 4 plus maleic anhydride has been utilized to deposit thin films with biologic synaptic functions. [401] Besides the TiCl 4 precursor, also titanium tetra-isopropoxide [45,135,136,210,217,227,265,351,409] and tetrakis(dimethylamido) titanium [112] precursors have be...…”