Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 13, Issue 15, Pages 17668-17676Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c02590
Keywords
potassium-ion batteries; electrode; SnS2 nanosheets; MXene; N and S co-doped
Funding
- National Key R&D Program of China [2018YFB0703704]
- National Natural Science Foundation of China [51720105002, 51973155, 51927806, 51921002, 51903004]
- HighPerformance Computing Platform of Peking University, China
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In this study, SnS2 nanosheets anchored on nitrogen and sulfur co-doped MXene were designed as advanced anode materials for potassium-ion batteries, showing superior performance with unique structure and cycling stability. Ex situ X-ray diffraction measurement revealed the multistep alloying reaction mechanism of SnS2 nanosheets/MXene composites with potassium ions, while density functional theory calculations confirmed the enhancement of structural stability and cycling electrochemical performance due to the existence of Ti-S bonds between SnS2 nanosheets and MXene.
Potassium-ion batteries (KIBs) are emerging as the prospective alternatives to lithium-ion batteries in energy storage systems owing to the sufficient resources and relatively low cost of K-related materials. However, serious volume expansion and low specific capacity are found in most materials systems resulting from the large intrinsic radius of K+. Herein, SnS2 nanosheets anchored on nitrogen and sulfur co-doped MXene (SnS2 NSs/MXene) are creatively designed as advanced anode materials for KIBs. SnS2 NSs/MXene with a unique hierarchical structure can not only provide fast transmission channels for K+ but also avoid the accumulation of K+ and volume expansion. These novel features make SnS2 NSs/MXene electrodes exhibit a superior reversible specific capacity of 342.4 mA h g(-1) under 50 mA g(-1). Also, they maintain 206.1 mA h g(-1) at an even higher current density of 0.5 A g(-1) over 800 cycles almost without capacity decay. Moreover, the multistep alloying reaction mechanism of SnS2 NSs/MXene composites and K+ is revealed by the ex situ Xray diffraction measurement. In addition, the density functional theory calculations confirm the existence of Ti-S bonds between SnS2 nanosheets and MXene, which significantly enhance the structural stability and cycling electrochemical performance of SnS2 NSs/MXene composites.
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