Layer-by-Layer Engineered Silicon-Based Sandwich Nanomat as Flexible Anode for Lithium-Ion Batteries.

Abstract

Lithium-ion batteries with high electrochemical performance and stable mechanical compliance are pivotal to propel the advanced wearable electronics forward. Herein, a high-conductive flexible electrode densified from multilayer lamellar unit cells with the silicon-based sandwich structure is rationally designed by molecular engineering. Silicon nanoparticles can be uniformly anchored to the surface of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) aerogel through hydrogen bonding, which effectively relaxes the drastic volume expansion of the Si-based anode. The graphite microsheets (GMs) attached on silicon nanoparticles allow the porous aerogel network to maintain excellent electrical connection in all directions, and after being switched to compact film, the conductive network enables a robust contact with silicon nanoparticles. As a result, the Si-based nanomat anode exhibits reliable cycling stability (639.4 mA h g-1 after 400 cycles at 1.0 A g-1) and enhanced rate capability (298.6 mA h g-1 at 1.6 A g-1). Notably, instead of conventional polyolefin separators, TOBC-reinforced silica aerogel is fabricated as an advanced separator to integrate the flexible all-in-one full-cell with freestanding GM/TOBC/silicon (GM/TOBC/Si) anode and GM/TOBC/LiFePO4 cathode. Driven by the unique structure and functional component, the flexible all-in-one lithium-ion batteries showcase exceptional deformation tolerance yet impressive charge/discharge behavior.