Surface functional group‐tailored B and N co‐doped carbon quantum dot anode for lithium‐ion batteries

Abstract

Summary Recently, carbon quantum dots (CQDs) have emerged as new surface modification agents for the anode materials of lithium‐ion batteries (LIBs) owing to their various advantages, including high surface area, low toxicity, low cost, and chemical stability. However, CQDs intrinsically possess large amounts of nonessential oxygen‐containing groups (CO and COH) at the surface, which can inhibit Li+ accessibility and lower electrical conductivity. Owing to these limitations, CQDs have been widely studied as composite agents and not as independent active materials. Therefore, to enhance the electrical conductivity and increase the Li+ diffusivity of CQDs, we suggest surface functional group‐tailored boron and nitrogen co‐doped carbon quantum dots (BN‐CQDs) for self‐reliant LIB anode applications. The 0.5BN‐CQD electrodes showed superior electrochemical performance, including outstanding ultrafast energy storage capability (130.4 mAh g−1 at 3000 mA g−1 with capacity retention of 88% up to 1000 cycles). This is contributed by the enhanced electrical conductivity of the boron and nitrogen co‐doped structure and high Li+ acceptability, which facilitated the formation of C═O surface functional groups due to the boron dopant. In this regard, we believe that the fabrication of self‐reliant 0.5BN‐CQD electrodes could be a promising research strategy for carbon‐based anode materials.

Boron and nitrogen double‐doped carbon flower prepared by in‐situ copolymerization as anode materials for lithium‐ion batteries

“…In the XRD lines of the six samples, two broad steamed bread‐like diffraction peaks were observed at 24 and 44°. These two peaks correspond to the (002) and (100) planes of graphite, 31,32 indicating a disordered structure, which is highly consistent with the results of the HRTEM. At the same time, it is also observed that the intensity of the diffraction peak around 44° increases slightly with the heat treatment temperature, suggesting the higher temperature will lead to a higher degree of graphitization of the sample.…”

Multifunctional Janus Separators for Safer and Dendrite‐Free Lithium‐Metal Batteries

“…First, the CQDs confers better Li ion transfer, charge carriers’ flux and, consequently, faster kinetics properties thanks to the presence of Nitrogen doping which generates additional active sites enhancing the overall lithiophilicity of the carbon‐based material. This positive effect has been also recently demonstrated in case of heteroatom (e. g., B, N or O)‐doped and/or co‐doped CQDs and other carbon materials (G, NG or GO) [40–42] . Additionally, the N‐doped CQDs can act on the solvation degree of Li + ions by inhibiting the formation of ion‐solvent (carbonates) clusters and promoting a better carrier migration [43] .…”

“…This positive effect has been also recently demonstrated in case of heteroatom (e. g., B, N or O)-doped and/or co-doped CQDs and other carbon materials (G, NG or GO). [40][41][42] Additionally, the N-doped CQDs can act on the solvation degree of Li + ions by inhibiting the formation of ion-solvent (carbonates) clusters and promoting a better carrier migration. [43] This results in improved cell rate performance and lifespan, as also found in case of polymer electrolytes gelled by LiPF 6 -based solutions.…”