Regulation of fiber surface nucleation kinetics via ordered nitrogen-rich carbon dots

Abstract

Three dimensional (3D) carbon-based current collectors have attracted much attentions as host for Li metal anodes (LMAs) owing to their lightweight, flexible, and wide sources etc. However, the lithiophobic nature of carbon makes it difficult to achieve low nucleation overpotential and dendrite-free Li deposition. Herein, carbon dots (CDs) with nitrogen (N)-rich were introduced to modify carbonized cotton fiber (CCF) coated by reduced graphene oxide (CD@RGCCF). Coating graphene oxide (GO) increases the active site of cotton fiber (CF), which facilitates the growth of CDs on the surface of CF fiber. The introduction of ordered structure CDs drives fast migration of Li+ in the “highway-like” channels and induces the uniform nucleation of Li in the initial stage. As a result, the obtained CD@RGCCF decreases the nucleation overpotential of Li, and achieves dendrite-free Li deposition. the CD@RGCCF|Li half cells exhibit extending cycling life over 5000 h with a voltage hysteresis of 10.5 mV at 2 mA cm−2. As coupled with the LiFePO4 (LFP), the Li@CD@RGCCF||LFP composite anode enables a high reversible specific capacity and improved cycle stability. This work provides a low-cost modification method for carbon substrate to realize dendritic-free LMAs.