Edge-boron-functionalized coal-derived graphite nanoplatelets prepared via mechanochemical modification for enhanced Li-ion storage at low-voltage plateau

Abstract

The low Li-ion storage and poor rate capability hinder the application of graphite anode in the next generation lithium-ion batteries. Among various carbonaceous anode materials, these endowed with high Li-ions storage performance at low operating voltage are still the focus. Herein, edge-boron-functionalized coal-derived graphite nanoplatelets (B-CGNs) are prepared by mechanochemical modification using anthracite as the precursor. The obtained B-CGNs have mildly-expanded and larger-sized graphitic layers with a lateral dimension of 1.0–2.0 μm, meanwhile the edges of nanoplatelets are functionalized by a small amount of boron atoms. The B-CGNs as anode for LIBs exhibit an enhanced Li-ions storage performance. In particular, it delivers superior specific capacity (530 mAh·g−1 at 0.05 A·g−1) and rate capability (335 and 145 mAh·g−1 at 2.0 and 5.0 A·g−1) in the low voltage window of 0.01–1.0 V, and excellent stability through long-term cycling up to 800 cycles (near 100% capacity retention). Theoretical calculation further demonstrates that mildly-expanded interlayer spacing and boron-functionalized edges in B-CGNs contribute to the improvement of the Li-ion storage capacity and diffusion ability.