高容量氟掺杂碳包覆纳米硅负极材料:气相氟化法制备及其储锂性能

F-doped Carbon Coated Nano-Si Anode with High Capacity:Preparation by Gaseous Fluorination and Performance for Lithium Storage

具有超高储锂比容量的硅材料是备受瞩目的高性能锂离子电池负极材料,但硅嵌锂时巨大的体积膨胀效应使之快速失效,从而限制了其应用性能。本研究提出一种简易低毒的气相氟化方法制备氟掺杂碳包覆纳米硅材料。通过在纳米硅表面包覆高缺陷度的氟掺杂碳层,抑制硅材料嵌锂体积膨胀,提供丰富的锂离子输运通道,同时形成富含LiF的稳定SEI膜。获得的氟掺杂碳包覆纳米硅负极在0.2~5.0 A·g^(–1)电流密度下,比容量达1540~580 mAh·g^(–1),循环200次后容量保持率>75%。本方法解决了传统氟化技术氟源(如XeF_(2)、F_(2)等)高成本、高毒性的问题。

Si anodes hold immense potential in developing high-energy Li-ion batteries.But fast failure due to huge volume change upon Li uptake impedes their application.This work reports a facile yet low-toxic gas fluorination way for yielding F-doped carbon-coated nano-Si anode materials.Coating of nano-Si with F-doped carbon containing high defects can effectively protect Si from huge volume change upon Li storage while facilitating Li+transport and formation of stable LiF-rich solid electrolyte interphase(SEI).This anode exhibits high capacities of 1540–580 mAh·g^(–1)at various current rates of 0.2–5.0 A·g^(–1),while retaining>75%capacity after 200 cycles.This method also addresses the issues of high cost and toxicity of traditional fluorination techniques that use fluorine sources such as XeF_(2) and F_(2).