Diamond-shaped Fe2O3@C18H34O2 core–shell nanostructures as anodes for lithium ion batteries with high over capacity

Abstract

The over capacity of lithium ion batteries with metal-oxides anode materials is usually regarded as originating from the low-voltage decomposition of the electrolyte and subsequent formation of a gel-like polymer layer deposited on the metal-oxides surfaces. In this work, we report a high over capacity value of 1800 mA h g⁻¹ after 350^th charge–discharge cycles for Fe₂O₃-made lithium ion batteries. It is found that the capacitive nature of the designed Fe₂O₃@C₁₈H₃₄O₂ nanostructure not only contributes to the large observed excess in capacity, but also results in unique rate capabilities. Thus, a capacitive model is proposed to outline a plausible mechanism to explain these electrochemical findings, and it is anticipated that this paper will shed some new light on future design of the next generation of lithium ion batteries.