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Metallic Graphene‐Like VSe 2 Ultrathin Nanosheets: Superior Potassium‐Ion Storage and Their Working Mechanism
Author(s) -
Yang Chao,
Feng Jianrui,
Lv Fan,
Zhou Jinhui,
Lin Chunfu,
Wang Kai,
Zhang Yelong,
Yang Yong,
Wang Wei,
Li Jianbao,
Guo Shaojun
Publication year - 2018
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201800036
Subject(s) - materials science , anode , pseudocapacitance , graphene , chemical engineering , intercalation (chemistry) , nanotechnology , energy storage , ion , electrode , supercapacitor , capacitance , inorganic chemistry , power (physics) , chemistry , physics , quantum mechanics , engineering
Potassium‐ion batteries (KIBs) are receiving increasing interest in grid‐scale energy storage owing to the earth abundant and low cost of potassium resources. However, their development still stays at the infancy stage due to the lack of suitable electrode materials with reversible depotassiation/potassiation behavior, resulting in poor rate performance, low capacity, and cycling stability. Herein, the first example of synthesizing single‐crystalline metallic graphene‐like VSe 2 nanosheets for greatly boosting the performance of KIBs in term of capacity, rate capability, and cycling stability is reported. Benefiting from the unique 2D nanostructure, high electron/K + ‐ion conductivity, and outstanding pseudocapacitance effects, ultrathin VSe 2 nanosheets show a very high reversible capacity of 366 mAh g −1 at 100 mA g −1 , a high rate capability of 169 mAh g −1 at 2000 mA g −1 , and a very low decay of 0.025% per cycle over 500 cycles, which are the best in all the reported anode materials in KIBs. The first‐principles calculations reveal that VSe 2 nanosheets have large adsorption energy and low diffusion barriers for the intercalation of K + ‐ion. Ex situ X‐ray diffraction analysis indicates that VSe 2 nanosheets undertake a reversible phase evolution by initially proceeding with the K + ‐ion insertion within VSe 2 layers, followed by the conversion reaction mechanism.