Extended Lifespan of Low-Cost Metal Silicon Anodes via a One-Step Wet Ball-Milling Process for Ultra-Thin Polymer Protecting Layer and Optimal Particle Size

Abstract

Silicon is a promising active material for lithium-ion batteries (LIBs) with a high theoretical capacity (∼4000 mA h g–1). However, there is a critical issue that the fabrication of the Si anode needs complicated and high-cost processes to alleviate the poor cyclic performance, such as nanostructuring. Furthermore, the Si anode requires a high component ratio of conductive agents and binder in the electrode. Herein, we report the fabrication of submicron Si particles coated by a polyacrylonitrile (PAN) layer with a highly polar nitrile group via a facile one-step wet ball-milling process. During the milling of Si particles in PAN solutions, PAN adheres to the Si surface and forms a nanometer coating layer. The nitrile groups of PAN enhance the electrolyte wettability and increase the lithium-ion pathways on the Si surface. These result in a stable solid electrolyte interphase (SEI) layer and reduce the internal resistance of the electrodes. Si anodes with an optimal particle size and PAN layer (SM-Si@PAN) exhibit a superior performance even at ultra-fast current density (50 A g–1). In addition, a full-cell with an NCM712 cathode shows an excellent performance.

Stabilizing the Solid Electrolyte Interface Using a Zero-Strain Feature Protective Layer for a High-Performance Silicon–Graphite Anode

“…The replacement of a graphite anode in commercial Li-ion batteries (LIBs) with a suitable anode with high capacity is essential to overcome the fast-growing demand for high-energy LIBs to support long-range electric vehicles (EVs) and high-performance electronic systems. − Silicon (Si) is highlighted as a potential and viable candidate for the anode material in next-generation high-energy batteries owing to the remarkable specific capacity of Si (3579 mAh g –1 ), which is greater than that of a conventional graphite anode (372 mAh g –1 ) by more than 10-fold, while also being abundant in nature. , However, the commercial utilization of the Si anode in batteries for real device usage is hindered by its vast volume change (∼300%). The volumetric changes of Si upon (de)lithiation are highly irreversible, causing particle pulverization and contact losses between particles. , As a result, a deterioration in the battery performance occurs over successive cycling owing to mechanical fractures and irreversible side reactions, leading to a massive amount of lithium (Li) consumption upon the alloying reaction. Several material designs, including the nanoengineering of the Si structure (nanotube, nanowire, nanosheet, and hollow structures), utilization of elastic binders (binders with the −COOH or −OH group), coating of buffer layers (MO x or carbon coating), and nanocompositing (Si/C composite), have been proposed and investigated to mitigate volume expansion in prior studies effectively.…”