School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, P. R. China.
Jiangsu Xinhua Semiconductor Technology Co., Ltd, China.
Nanoscale. 2023 Jan 27;15(4):1568-1582. doi: 10.1039/d2nr05885e.
The development of graphitic carbon materials as anodes of sodium-ion batteries (SIBs) is greatly restricted by their inherent low specific capacity. Herein, nitrogen and sulfur co-doped 3D graphene frameworks (NSGFs) were successfully synthesized a simple and facile one-step hydrothermal method and exhibited high Na storage capacity in ether-based electrolytes. A systematic comparison was made between NSGFs, undoped graphene frameworks (GFs) and nitrogen-doped graphene frameworks (NGFs). It is demonstrated that the high specific capacity of NSGFs can be attributed to the free diffusion of Na ions within the graphene layer and reversible reaction between -C-S-C- covalent chains and Na ions thanks to the large interplanar distance and the dominant -C-S-C- covalent chains in NSGFs. NSGF anodes, therefore, exhibit a high initial coulombic efficiency (ICE) (92.8%) and a remarkable specific capacity of 834.0 mA h g at 0.1 A g. Kinetic analysis verified that the synergetic effect of N/S co-doping not only largely enhanced the Na ion diffusion rate but also reduced the electrochemical impedance of NSGFs. Postmortem techniques, such as SEM, XPS, HTEM and Raman spectroscopy, all demonstrated the extremely physicochemically stable structure of the 3D graphene matrix and ultrathin inorganic-rich solid electrolyte interphase (SEI) films formed on the surface of NSGFs. Yet it is worth noting that the Na storage performance and mechanism are exclusive to ether-based electrolytes and would be inhibited in their carbonate ester-based counterparts. In addition, the corrosion of copper foils under the synergetic effect of S atoms and ether-based electrolytes was reported for the first time. Interestingly, by-products derived from this corrosion could provide additional Na storage capacity. This work sheds light on the mechanism of improving the electrochemical performance of carbon-based anodes by heteroatom doping in SIBs and provides a new insight for designing high-performance anodes of SIBs.
将石墨碳材料开发为钠离子电池（SIBs）的阳极受到其固有低比容量的极大限制。在此，通过简单易行的一步水热法成功合成了氮硫共掺杂的 3D 石墨烯框架（NSGFs），并在醚基电解液中表现出高的储钠能力。对 NSGFs、未掺杂的石墨烯框架（GFs）和氮掺杂的石墨烯框架（NGFs）进行了系统比较。结果表明，NSGFs 的高比容量归因于石墨烯层内钠离子的自由扩散以及 -C-S-C-共价键与钠离子之间的可逆反应，这得益于 NSGFs 中的大层间距和主导的 -C-S-C-共价键。因此，NSGF 阳极具有高的初始库仑效率（ICE）（92.8%）和 834.0 mA h g 在 0.1 A g 时的显著比容量。动力学分析证实，N/S 共掺杂的协同效应不仅大大提高了钠离子的扩散速率，而且降低了 NSGFs 的电化学阻抗。SEM、XPS、HTEM 和 Raman 光谱等后处理技术均表明 3D 石墨烯基质具有极其稳定的物理化学结构，以及在 NSGFs 表面形成的超薄无机富固态电解质界面（SEI）膜。值得注意的是，储钠性能和机制仅限于醚基电解液，在其碳酸酯基电解液中会受到抑制。此外，首次报道了 S 原子和醚基电解液协同作用下对铜箔的腐蚀。有趣的是，这种腐蚀的副产物可以提供额外的储钠容量。这项工作揭示了在 SIBs 中通过杂原子掺杂来提高碳基阳极电化学性能的机制，并为设计高性能 SIBs 阳极提供了新的思路。
