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Ultrafast Discharge/Charge Rate and Robust Cycle Life for High‐Performance Energy Storage Using Ultrafine Nanocrystals on the Binder‐Free Porous Graphene Foam
Author(s) -
Lee Gyu Heon,
Lee Jung Woo,
Choi Ji IL,
Kim Sang Jun,
Kim YongHoon,
Kang Jeung Ku
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201601355
Subject(s) - materials science , graphene , mesoporous material , nanocrystal , nanotechnology , ion , nanoparticle , chemical engineering , energy storage , faraday efficiency , electrode , electrolyte , catalysis , physics , power (physics) , quantum mechanics , engineering , biochemistry , chemistry
A hierarchical architecture fabricated by integrating ultrafine titanium dioxide (TiO 2 ) 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 TiO 2 –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.