Tailoring mulberry-like Fe2O3 architecture assembled by quantum dots on rGO to enable high pseudocapacitance and controllable solid electrolyte interphase

Constructing pseudocapacitive materials to combine the battery-level energy density with the cycle life and power density of supercapacitors is a promising energy storage technique. Nanostructuring can greatly induce extrinsic pseudocapacitance, but excessive solid electrolyte interphase (SEI) as the activity surface increases usually results in a poor coulombic efficiency (CE) of battery. Here, we separately investigate the electrochemical properties of self-assembled Fe2O3 "mulberry" architecture, quantum dots and bulk particles. Employed as an anode of lithium ion battery, the mulberry architecture retains a dominant pseudocapacitance behavior and high electrochemical activity. It delivers an initial capacity of 1383.8 mAh g−1, 22.1% higher than Fe2O3 bulk in similar size, in which the pseudocapacitance contribution up to 80.6% at 0.4 mV s−1. Furthermore, the mulberry architecture decreases the activity surface contacted with electrolyte to enable a limited SEI, achieving a higher coulombic efficiency (initial CE: 80.1%, average CE: 98.9%) well above that of individual quantum dots. This work is expected to inspire the design of novel high-performance anode materials.