Ultrafast Discharge/Charge Rate and Robust Cycle Life for High-Performance Energy Storage Using Ultrafine Nanocrystals on the Binder-Free Porous Graphene Foam

A hierarchical architecture fabricated by integrating ultrafine titanium dioxide (TiO2) nanocrystals with the binder‐free macroporous graphene (PG) network foam for high‐performance energy storage is demonstrated, where mesoporous open channels connected to the PG facilitate rapid ionic transfer dur...

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Bibliographic Details
Published in:Advanced functional materials 2016-07, Vol.26 (28), p.5139-5148
Main Authors: Lee, Gyu Heon, Lee, Jung Woo, Choi, Ji IL, Kim, Sang Jun, Kim, Yong-Hoon, Kang, Jeung Ku
Format: Article
Language:English
Subjects:
binder-free macroporous graphene foam
Charge
Discharge
Extraction
fast discharge/charge rate
Foams
Graphene
high-power energy storage
Insertion
Networks
robust cycle life
Titanium dioxide
ultrafine nanocrystal
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Summary:A hierarchical architecture fabricated by integrating ultrafine titanium dioxide (TiO2) nanocrystals with the binder‐free macroporous graphene (PG) network foam for high‐performance energy storage is demonstrated, where mesoporous open channels connected to the PG facilitate rapid ionic transfer during the Li‐ion insertion/extraction process. Moreover, the binder‐free conductive PG network in direct contact with a current collector provides ultrafast electronic transfer. This structure leads to unprecedented cycle stability, with the capacity preserved with nearly 100% Coulombic efficiency over 10 000 Li‐ion insertion/extraction cycles. Moreover, it is proven to be very stable while cycling 10 to 100‐fold longer compared to typical electrode structures for batteries. This facilitates ultrafast charge/discharge rate capability even at a high current rate giving a very short charge/discharge time of 40 s. Density functional theory calculations also clarify that Li ions migrate into the TiO2–PG interface then stabilizing its binder‐free interface and that the Li ion diffusion occurs via a concerted mechanism, thus resulting in the ultrafast discharge/charge rate capability of the Li ions into ultrafine nanocrystals. A hierarchical architecture fabricated by integrating ultrafine (≈6 nm) TiO2 nanoparticles (NPs) on the binder‐free macroporous graphene (PG) network foam for high‐performance energy storage enabling ultrafast rate and robust cycle life is reported, where the mesoporous open channels created by ultrafine NPs and also the binder‐free conductive PG network facilitate fast ionic transfer during Li‐ion insertion/extraction.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201601355