A Robust Solid Electrolyte Interphase Layer Augments the Ion Storage Capacity of Bimetallic‐Sulfide‐Containing Potassium‐Ion Batteries

Metal–organic framework‐derived NiCo2.5S4 microrods wrapped in reduced graphene oxide (NCS@RGO) were synthesized for potassium‐ion storage. Upon coordination with organic potassium salts, NCS@RGO exhibits an ultrahigh initial reversible specific capacity (602 mAh g−1 at 50 mA g−1) and ultralong cycl...

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Published in:Angewandte Chemie International Edition 2019-10, Vol.58 (41), p.14740-14747
Main Authors: Xie, Junpeng, Li, Xiaodan, Lai, Haojie, Zhao, Zhijuan, Li, Jinliang, Zhang, Wanggang, Xie, Weiguang, Liu, Yiming, Mai, Wenjie
Format: Article
Language:English
Subjects:
Atomic force microscopy
Batteries
Bimetals
Byproducts
Chemical synthesis
Electrodes
Electrolytes
Graphene
Interphase
interphase layers
Ion storage
Metal-organic frameworks
Microscopy
NiCo2.5S4 microrods
organic potassium salts
Potassium
Potassium salts
Rechargeable batteries
reduced graphene oxide
Robustness
Salts
Solid electrolytes
Specific capacity
Storage batteries
Storage capacity
Sulfide
Sulfides
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Summary:Metal–organic framework‐derived NiCo2.5S4 microrods wrapped in reduced graphene oxide (NCS@RGO) were synthesized for potassium‐ion storage. Upon coordination with organic potassium salts, NCS@RGO exhibits an ultrahigh initial reversible specific capacity (602 mAh g−1 at 50 mA g−1) and ultralong cycle life (a reversible specific capacity of 495 mAh g−1 at 200 mA g−1 after 1 900 cycles over 314 days). Furthermore, the battery demonstrates a high initial Coulombic efficiency of 78 %, outperforming most sulfides reported previously. Advanced ex situ characterization techniques, including atomic force microscopy, were used for evaluation and the results indicate that the organic potassium salt‐containing electrolyte helps to form thin and robust solid electrolyte interphase layers, which reduce the formation of byproducts during the potassiation–depotassiation process and enhance the mechanical stability of electrodes. The excellent conductivity of the RGO in the composites, and the robust interface between the electrodes and electrolytes, imbue the electrode with useful properties; including, ultrafast potassium‐ion storage with a reversible specific capacity of 402 mAh g−1 even at 2 A g−1. The potassium‐ion storage performance of a NiCo2.5S4 composite electrode improves in a potassium bis(fluorosulfonyl) imide, ethylene and propylene carbonate mixed electrolyte (KFSI‐EP, EPF (doped with fluoroethylene carbonate)). Performance declines in KPF6‐ or fluoroethylene‐carbonate‐containing electrolytes. A robust solid electrolyte interphase layer increases performance in a potassium‐ion battery. Scale: 10 μm.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201908542