Journal
ACS APPLIED MATERIALS & INTERFACES
Volume 11, Issue 43, Pages 39737-39745Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b10055
Keywords
fluorinated graphene; lithium anode; Li-02 cell; density functional theory; in situ optical microscopy
Funding
- National Natural Science Foundation of China [51572238]
- Zhejiang Provincial Natural Science Foundation of China [LY19E020013]
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Metallic Li is considered as the ultimate choice of negative electrodes for Li batteries because of its largest theoretical specific capacity. However, formidable issues such as poor safety and cyclability caused by lithium dendrite growth and tremendous interfacial side reactions have strictly hindered its practical applications. Here, we report a fluorinated graphene (FG)-modified Li negative electrode (LFG) for high-performance lithium oxygen (Li-02) cells. The results show that only 3 wt % FG introduction leads to a significant enhancement on rate capability and cycling life of Li electrodes. Compared with the half cells with bare Li, the cells with LFG exhibit much more stable voltage profiles even at a large areal capacity up to 5 mA h cm' or a large current density up to S mA cm-2. Li-02 cells with the LFG anode show a longer cycle life than the cell with the pristine lithium anode. It was found that a LiF-rich layer could be in situ built upon cycling when FG was used, which ensures uniform Li stripping/ plating and effectively suppresses Li dendrite growth. Density functional theory calculations confirm the possibility of conversion from FG to graphene and LiF after Li intercalation into LFG during cycling. In situ optical microscopy observation vividly exhibits the obvious inhibition effect of FG for Li dendrite growth.
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