Yang Jing, Luo Jinda, Kuang Yi, He Yichu, Wen Piaopiao, Xiong Lingling, Wang Xianyou, Yang Zhenhua
Key Laboratory of Low Dimensional Materials & Application Technology of Ministry of Education, School of Materials Science and Engineering, Xiangtan University, Xiangtan 411105, Hunan, China.
National Base for International Science & Technology Cooperation, National-Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery, Hunan Province Key Laboratory of Electrochemical Energy Storage and Conversion, School of Chemistry, Xiangtan University, Xiangtan 411105, China.
ACS Appl Mater Interfaces. 2021 Jan 13;13(1):2072-2080. doi: 10.1021/acsami.0c19934. Epub 2020 Dec 21.
As typical 2D materials, VSe and MoSe both play a complementary role in Li/Na/K storage. Therefore, we designed and optimized the VSe/MoSe heterostructure to gain highly efficient Li/Na/K-ion batteries. Most importantly, achieving fast Li/Na/K-ion diffusion kinetics in the interlayer of VSe/MoSe is a key point. First of all, first-principles calculations were carried out to systematically investigate the packing structure, mechanical properties, band structure, and Li/Na/K storage mechanism. Our calculated results suggest that a large interlayer spacing (3.80 Å), robust structure, and metallic character pave the way for achieving excellent charge-discharge performance for the VSe/MoSe heterostructure. Moreover, V and Mo ions both suffer a very mild redox reaction even if Li/Na/K ions fill the interlayer space. These structures were all further verified to show thermal stability (300 K) by means of the AIMD method. By analyzing the Li/Na/K diffusion behavior and the effect of vacancy defect on the structural stability and energy barrier for Li interlayer diffusion, it is found that the VSe/MoSe heterostructure exhibits very low-energy barriers for Na/K interlayer diffusion (0.21 eV for Na and 0.11 eV for K). Compared with the VSe/MoSe heterostructure, the VSe/MoSe heterostructure not only can still maintain a stable structure and metallic character but also has much lower energy barrier for Li interlayer diffusion (0.07 0.48 eV). These discoveries also break new ground to eliminate the obstacles preventing Li diffusion in the interlayer of other heterostructure materials. Besides, both VSe/MoSe and VSe/MoSe heterostructures have low average open-circuit voltage (OCV) values during Li/Na/K interlayer diffusion (1.07 V for VSe/MoSe Li, 0.86 V for VSe/MoSe Na, and 0.54 V for VSe/MoSe K), such low OCV values are beneficial for anode materials with excellent electrochemical properties. The above findings offer a new route to design anode materials for Li/Na/K-ion batteries.
作为典型的二维材料，VSe和MoSe在锂/钠/钾存储中都发挥着互补作用。因此，我们设计并优化了VSe/MoSe异质结构以获得高效的锂/钠/钾离子电池。最重要的是，在VSe/MoSe的层间实现快速的锂/钠/钾离子扩散动力学是一个关键点。首先，进行了第一性原理计算，以系统地研究堆积结构、力学性能、能带结构和锂/钠/钾存储机制。我们的计算结果表明，较大的层间距（3.80 Å）、稳健的结构和金属特性为VSe/MoSe异质结构实现优异的充放电性能铺平了道路。此外，即使锂/钠/钾离子填充层间空间，V和Mo离子也都经历非常温和的氧化还原反应。通过AIMD方法进一步验证了这些结构在300 K时具有热稳定性。通过分析锂/钠/钾扩散行为以及空位缺陷对锂层间扩散的结构稳定性和能垒的影响，发现VSe/MoSe异质结构对钠/钾层间扩散表现出非常低的值（钠为0.21 eV，钾为0.11 eV）。与VSe/MoSe异质结构相比，VSe/MoSe异质结构不仅仍能保持稳定的结构和金属特性，而且锂层间扩散的能垒也低得多（0.07至0.48 eV）。这些发现也为消除阻碍锂在其他异质结构材料层间扩散的障碍开辟了新途径。此外，VSe/MoSe和VSe/MoSe异质结构在锂/钠/钾层间扩散过程中都具有较低的平均开路电压（OCV）值（VSe/MoSe锂为1.07 V，VSe/MoSe钠为0.86 V，VSe/MoSe钾为0.54 V），如此低的OCV值有利于具有优异电化学性能的负极材料。上述发现为设计锂/钠/钾离子电池的负极材料提供了一条新途径。
