Nanoarchitecting with a Reversible Template: A Green Route to Gradient SiO x Anode via Hydrophilic/Hydrophobic Switching for Advanced Lithium-Ion Batteries

Abstract

High-capacity SiOx anode materials are difficult to commercialize due to poor conductivity and large volume fluctuations. Constructing nanostructured SiOx/C composites has been proven as one of the effective approaches. However, the structural design of a SiOx/C composite usually involves the use of templates and relies on chemical etching and organic solvents to remove the template, which causes environmental pollution and hinders the reuse of templates. This study proposes a green template strategy. By exploiting its phase transition of poly(N-isopropylacrylamide) (PNIPAM) at specific temperatures, a nanoscale template is provided for the hydrolysis and deposition process of silicon source and solves the problem when removing template. The prepared SiOx@NC is features a gradient distribution of silicon valence states, as demonstrated by X-ray photoelectron spectroscopy depth profiling. N-doped carbon coating constructs a stable interfacial framework that facilitates electron transport and lithium-ion diffusion. The discharge capacity of SiOx@NC was maintained at 612.2 mAh g−1 after 500 cycles at a current density of 1 A g−1. The material in the Li-ion full cell delivers a reversible capacity of 117.57 mAh g−1, demonstrating its promising practical applications in LIBs. Our work will open up a feasible and eco-friendly preparation path for silicon-based anode materials in high-energy-density and long-life LIBs.