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Enhanced Electrochemical Performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 by Expanded Graphite
Author(s) -
Peng Zhenfeng,
Tang Wenjie,
Peng Yujia,
Qiu Yang,
Shuai Hantao,
Wang Guixin
Publication year - 2019
Publication title -
energy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 44
eISSN - 2194-4296
pISSN - 2194-4288
DOI - 10.1002/ente.201900614
Subject(s) - materials science , electrochemistry , graphite , chemical engineering , aqueous solution , ternary operation , hydrothermal circulation , graphene , nanotechnology , electrode , metallurgy , chemistry , computer science , engineering , programming language
High‐capacity ternary materials are attractive for the development of electric vehicles for long‐distance driving, but they still face some challenges. To improve the performance, expanded graphite (EG) with a unique loose‐layered structure is mixed with (Ni 0.6 Co 0.2 Mn 0.2 )(OH) 2 and LiOH·H 2 O aqueous solution to supply microscale reaction space and limit grain growth via hydrothermal treatment as well as accommodate LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) particles between the graphene layers. The key factors affecting electrochemical performance are investigated using various techniques. The NCM622 sample synthesized by adding 6.6 wt% of EG (PEG6.6%) exhibits the best performance. EG improves the discharge capacity of NCM622 from 156 to 175 mAh g −1 after 50 cycles at 1 C. As the surrounding temperature increases to 60 °C, the sample also shows good cyclability at 1 C, the 50th discharge specific capacity remains 153 mAh g −1 and the capacity retention rate is 82.3%, which is much higher than that of NCM622. Also, the columbic efficiency of NCM622 after 50 cycles improves from 69% to 99% with EG. The possible enhanced mechanism of NCM622 by EG is discussed. The effective way to enhance the performance using the layered structure of EG is promising for other energy materials.