Lee Dong Kyu, Chae Yoonjeong, Yun Hwajin, Ahn Chi Won, Lee Jae W
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Department of Global Nanotechnology Development Team, National Nanofab Center at Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
ACS Nano. 2020 Aug 25;14(8):9744-9754. doi: 10.1021/acsnano.0c01452. Epub 2020 Aug 5.
Lithium-sulfur (Li-S) batteries are one of the main challenges facing Li-ion technology because the insulating nature of sulfur and the shuttle phenomenon of dissolved lithium polysulfides (LPSs) in liquid electrolytes result in critical problems, including low Coulombic efficiency, loss of active material, and rapid capacity decay. Here, we oxidized delaminated transition metal carbides (MXenes) using CO (Oxi-d-MXenes) and used them as both cathode electrode with sulfur and modified separator coated onto the glass fiber without a conductive material and binder to suppress the diffusion of LPSs. Oxi-d-MXenes annealed at 900 °C using CO gas formed perfectly converted rutile-TiO nanocrystalline particles on their two-dimensional sheets. Li-S batteries fabricated with the Oxi-d-MXenes cathode and the Oxi-d-MXenes-modified separator exhibited high Coulombic efficiency (nearly 99%) and retained a capacity of about 900 mAh g after 300 cycles at a current density of 1C. These results were attributed to the chemical and physical adsorption between the Oxi-d-MXenes and the LPSs. Our results imply that Oxi-d-MXenes prepared by the CO treatment exhibit physical and electrochemical properties that enhance the performance of Li-S batteries.
锂硫（Li-S）电池是锂离子技术面临的主要挑战之一，因为硫的绝缘性质以及溶解的多硫化锂（LPSs）在液体电解质中的穿梭现象导致了一些关键问题，包括低库仑效率、活性材料损失和快速的容量衰减。在此，我们使用CO对分层的过渡金属碳化物（MXenes）进行氧化（氧化-MXenes），并将其既用作含硫的阴极电极，又用作涂覆在无导电材料和粘结剂的玻璃纤维上的改性隔膜，以抑制LPSs的扩散。使用CO气体在900℃下退火的氧化-MXenes在其二维片层上形成了完美转化的金红石型TiO纳米晶体颗粒。用氧化-MXenes阴极和氧化-MXenes改性隔膜制造的锂硫电池表现出高库仑效率（接近99%），并且在1C电流密度下循环300次后仍保持约900 mAh g的容量。这些结果归因于氧化-MXenes与LPSs之间的化学和物理吸附。我们的结果表明，通过CO处理制备的氧化-MXenes表现出增强锂硫电池性能的物理和电化学性质。
