Boron-tailored starbon for fast-charging and stable-cycling lithium-ion batteries.

Abstract

Starbon derived from starch exhibits tunable surface functionality and high porosity, making them prominent candidates in energy storage technology. However, the poor fast-charging and limited stable-cycling properties of starbon limits the broad applications of lithium-ion batteries (LIBs) in practical scenarios. Herein, a boron-tailored approach was proposed to promote Li-ion migration and retard capacity decay of starbon anode. A boron solid-solution phase such as BC₂O was formed in the starbon framework by a simple pentaborate starch hydrothermal reaction and annealing process, and then boron quantum dots (BQDs) were confined within conductive boron-doped starbon. The electron-deficient BQDs endow the boronated starbon framework with superior electrochemical performance, vastly enabling the electrochemical activity of boron as well as providing more active sites for ion insertion and extraction, thus increasing capacity and improving ion charge/diffusion and transfer. As an anode material for LIBs, BQDs/Starbon anode exhibits a high discharge capacity of 928 mAh g^-1 at 0.05 A g^-1, and the reversible specific capacity remains at 238 mAh g^-1 at 2 A g^-1 after 1000 cycles, demonstrating excellent long-term cycling stability. After cycling at a high current density of 10 A g^-1 to recover to the initial 0.5 A g^-1, the electrode was still able to maintain a high capacity of 318 mAh g^-1. The excellent lithium storage properties demonstrated the composite anode of BQDs and biomass starbon is feasible, providing more choices for the development of anode materials for lithium-ion batteries.