Metallasilsesquioxane-derived ultrathin porous carbon nanosheet 3D architectures an " dual templating" strategy for ultrafast sodium storage

Porous carbon is usually used as an anode material for fast sodium storage due to its exceptional pore structure and high electrical conductivity. Herein, lithium hepta(i-butyl)silsesquioxane trisilanolate (T7-Li) is directly pyrolyzed to fabricate ultrathin porous carbon nanosheet 3D architectures (PCNS) via a novel " in situ dual templating" strategy. On one hand, the organic groups of T7-Li act as carbon sources for PCNS, and on the other hand, the pyrolysis of the inorganic core in T7-Li can generate both silica nanoparticles which act as a template for the formation of a porous structure, and most significantly, lithium silicate nanosheets formed by the reaction of silica and lithium oxide which serve as an inducer for the formation of carbon nanosheets. Impressively, when applied as the anode material for Na-ion batteries, PCNS delivers an ultrafast capacity of 230.5 mA h g −1 at 10 A g −1 . Furthermore, the Na-ion capacitor assembled using PCNS as both the anode and cathode delivers an extremely high energy density of 137 W h kg −1 at 3454 W kg −1 . This work proposes a novel strategy for the synthesis of porous carbon nanosheets for fast sodium storage and provides more possibilities to enrich the application of metallasilsesquioxanes. It is the first time that metallasilsesquioxanes are introduced into the synthesis of porous carbon nanosheets. Lithium hepta(i-butyl)silsesquioxane trisilanolate is a multifunctional precursor for both carbon sources and templates with different dimensions.