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Carbon Nanotube–CoF 2 Multifunctional Cathode for Lithium Ion Batteries: Effect of Electrolyte on Cycle Stability
Author(s) -
Wang Xinran,
Gu Wentian,
Lee Jung Tae,
Nitta Naoki,
Benson Jim,
Magasinski Alexandre,
Schauer Mark W.,
Yushin Gleb
Publication year - 2015
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201501139
Subject(s) - materials science , electrolyte , cathode , carbon nanotube , anode , nanocomposite , lithium (medication) , chemical engineering , ionic conductivity , dissolution , carbon fibers , composite material , nanotechnology , electrode , composite number , chemistry , medicine , engineering , endocrinology
Transition metal fluorides (MF x ) offer remarkably high theoretical energy density. However, the low cycling stability, low electrical and ionic conductivity of metal fluorides have severely limited their applications as conversion‐type cathode materials for lithium ion batteries. Here, a scalable and low‐cost strategy is reported on the fabrication of multifunctional cobalt fluoride/carbon nanotube nonwoven fabric nanocomposite, which demonstrates a combination of high capacity (near‐theoretical,550mAhgCoF 2− 1) and excellent mechanical properties. Its strength and modulus of toughness exceed that of many aluminum alloys, cast iron, and other structural materials, fulfilling the use of MF x ‐based materials in batteries with load‐bearing capabilities. In the course of this study, cathode dissolution in conventional electrolytes has been discovered as the main reason that leads to the rapid growth of the solid electrolyte interphase layer and attributes to rapid cell degradation. And such largely overlooked degradation mechanism is overcome by utilizing electrolyte comprising a fluorinated solvent, which forms a protective ionically conductive layer on the cathode and anode surfaces. With this approach, 93% capacity retention is achieved after 200 cycles at the current density of 100 mA g −1 and over 50% after 10 000 cycles at the current density of 1000 mA g −1 .