Abstract:

Due to graphite's advantages such as abundant resources, high specific capacity and low lithium intercalation voltage, it is considered an important commercial anode for lithium-ion batteries (LIBs). However, the lower theoretical specific capacity of graphite limits further improvement in the energy density of LIBs. Therefore, in this study, a graphite/SiO composite anode was obtained by adding a small amount of silicon oxide (SiO) to graphite, which was then dispersed into a small amount of O,S co-doped double-walled carbon nanotube (O,S-DCNTs) aqueous conductive additive. The O,S-DCNTs were prepared by pre-oxidizing double-walled carbon nanotubes (DCNTs) in air and then mixing and calcining them with MgSO₄, possessing abundant nanoscale pore structures, high sulfur content and strong hydrophilicity. Battery performance tests revealed that the introduction of $\mathrm{O},\mathrm{S}-\mathrm{D}\mathrm{C}\mathrm{N}\mathrm{T}\mathrm{s}$ significantly improved the specific capacity, rate capability and cycling stability of the graphite/SiO composite anodes. Additionally, its cycling stability was four times that of graphite/SiO anodes containing pure sulfur-doped carbon nanotubes (S-DCNTs). This improvement was mainly attributed to the highly dispersed $\mathrm{O},\mathrm{S}-$DCNTs, which can construct numerous conductive networks, provide abundant Li⁺ storage space and active sites, and address the issues of poor conductivity and large volume expansion coefficient of SiO, thereby significantly enhancing the electrochemical performance of the graphite anode. This work provided new insights and directions for the preparation and energy storage applications of high-performance anode materials.

Key words: double-walled carbon nanotubes, silicon monoxide, graphite anode, aqueous conductive additive, energy storage, nanomaterials, composites, electrochemistry

摘要：

由于石墨具有资源丰富、比容量高和嵌锂电位低等优势，被视为重要的商业化锂离子电池（LIBs）负极材料。然而，石墨较低的理论比容量限制了LIBs能量密度的进一步提升。因此，本文将少量的氧化亚硅（SiO）添加到石墨中，再分散到少量的氧硫掺杂双壁碳纳米管（O,S-DCNTs）水系导电剂中，得到石墨/SiO复合负极。其中，O,S-DCNTs是通过将双壁碳纳米管（DCNTs）在空气中预氧化处理，再通过浸渍法与MgSO₄混合后煅烧所得的，具有纳米孔结构丰富、硫含量高和亲水性强等特性。通过电池性能测试发现，引入O,S-DCNTs后石墨/SiO复合负极的比容量、倍率和循环性能得到显著提升。此外，其循环性能是纯硫掺杂碳纳米管（S-DCNTs）石墨/SiO负极的4倍，这主要归因于高分散的O,S-DCNTs能够构筑大量的导电网络，提供丰富的锂离子存储空间和活性位点，解决SiO导电性差和体积膨胀系数大问题，从而显著提高石墨负极的电化学性能。本文为高性能负极材料的制备与储能应用提供了新的思路和方向。

关键词: 双壁碳纳米管, 氧化亚硅, 石墨负极, 水系导电剂, 储能, 纳米材料, 复合材料, 电化学