Nb2O5 quantum dots coated with biomass carbon for ultra-stable lithium-ion supercapacitors

Quantum dots can reduce volumetric stress, improve anodic dynamics and shorten migration distance of lithium ions. In this work, Nb2O5 quantum dots (about 4 nm) coated with heteroatom biomass carbon (protein) are used as anode material (Nb2O5@NC) of lithium-ion capacitor. High dispersal quantum dots are prepared by strong associated reaction of amino acids (egg white) and metal cations (Nb5+). The Nb2O5@NC nanostructure can effectively avoid the aggregation of Nb2O5 quantum dots and adjust the mechanical stress caused by volume change. In addition to the enhanced electrical conductivity, biomass carbon also can maintain the stable solid-liquid interface to enhance the stability of electrode structure. In fact, Nb2O5@NC electrode still holds 82.1% storage capacity after 3000 cycles. (C) 2020 Elsevier B.V. All rights reserved.