材料科学
电化学
阳极
结晶
无定形固体
相(物质)
电极
X射线光电子能谱
离子
化学工程
X射线吸收光谱法
纳米技术
结晶学
物理化学
化学
吸收光谱法
有机化学
量子力学
物理
工程类
作者
Andrzej Kulka,Anna Plewa,Katarzyna Walczak,Justyna Płotek,Jianguo Sun,Li Lü,Camelia N. Borca,Thomas Huthwelker
标识
DOI:10.1016/j.ensm.2022.03.031
摘要
One of the major bottlenecks of Na-ion batteries (SIBs) is the lack of appropriate anode materials. The promising candidate is MoS2 exhibiting a very high specific capacity that unfortunately decreases after the first discharge due to structural reorganizations. Furthermore, the electrochemical reactions of MoS2 during subsequent cycles, which determine the performance of the cycle, remain unclear. This study elaborates the detailed phase evolution of few-layered 2H-MoS2 with an enhanced electrochemical performance by multiple operando/ex-situ techniques (XRD, XAS, XPS). Novel concept of MoS2 (de)sodiation mechanism is proposed based on repetitive disintegration and rearrangement of Na2S, Na2S2 and Mo accompanied by amorphization of the sulfur deficient NaxMoSy phase followed by NaxMo3S4 crystallization from an amorphous matrix through electrochemically driven congruent crystallization. The high Na-ion diffusion in the NaxMo3S4 phase and the fast propagation of the interface between the crystallized and the amorphous regions enable very high electrode reaction kinetics. The presented iterative conversion processes accompanied by amorphization and electrochemically driven congruent crystallization reactions provide new insight into the electrochemical (de)sodiation processes of MoS2, which contributes to the rational design of MoS2 electrodes and enriches the fundamental understanding of conversion reaction chemistry.
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