Bi‐Directional H‐Bonding Modulated Soft/Hard Polyethylene Glycol‐Polyaniline Coated Si‐Anode for High‐Performance Li‐Ion Batteries

Abstract

AbstractUltrahigh‐capacity silicon (Si) anodes are essential for the escalating energy demands driven by the booming e‐transportation and energy storage field. However, their practical applications are strictly hampered by their intrinsically low electroconductivity, sluggish Li‐ion diffusion, and undesirably large volume change. Herein, a high‐performance Si anode, comprised of a modulated soft/hard coating of polyethylene glycol (PEG) (as Li‐ion conductor) and polyaniline (PANI) (as electron conductor) on the surface of Si nanoparticles (NPs) through H‐bonding network, is introduced. In this design, the abundant ─OH groups of soft PEG allow it to uniformly cover Si NPs while the hard PANI binds to PEG through its ─N─H group, thus constructing a tight connectin between Si and PEG‐PANI (PP). Consequently, the elastic PP allows Si@PP to accommodate the huge volume expansion while possessing fine electronic/ionic conductivity. Therefore, the Si@PP anode exhibits a high initial Coulombic efficiency of 90.5% and a stable capacity of 1871 mAh g−1 after 100 cycles at 1 A g−1 with a retention of 85.7%. Additionally, the Si@PP anode also demonstrates a high areal capacity of 3.01 mAh cm−2 after 100 cycles at 0.5 A g−1. This work reveals a scalable interface design of multi‐layer multifunctional coatings for high‐performance electrode materials in next‐generation Li‐ion batteries.