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Functionalized Graphene for High Performance Lithium Ion Capacitors
Author(s) -
Lee Ji Hoon,
Shin Weon Ho,
Ryou MyungHyun,
Jin Jae Kyu,
Kim Junhyung,
Choi Jang Wook
Publication year - 2012
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201200549
Subject(s) - graphene , supercapacitor , materials science , oxide , lithium (medication) , graphite oxide , graphite , carbon fibers , power density , nanotechnology , electrochemistry , specific energy , chemical engineering , electrode , chemistry , composite number , power (physics) , composite material , medicine , physics , quantum mechanics , endocrinology , engineering , metallurgy
Lithium ion capacitors (LICs) have recently drawn considerable attention because they utilize the advantages of supercapacitors (high power) and lithium ion batteries (high energy). However, the energy densities of conventional LICs, which consist of a pair of graphite and activated carbon electrodes, are limited by the small capacities of the activated carbon cathodes. To overcome this limitation, we have engaged urea‐reduced graphene oxide. The amide functional groups generated during the urea reduction facilitate the enolization processes for reversible Li binding, which improves the specific capacity by 37 % compared to those of conventional systems such as activated carbon and hydrazine‐reduced graphene oxide. Utilizing the increased Li binding capability, when evaluated based on the mass of the active materials on both sides, the LICs based on urea‐reduced graphene oxide deliver a specific energy density of approximately 106 Wh kg total −1 and a specific power density of approximately 4200 W kg total −1 with perfect capacity retention up to 1000 cycles. These values are far superior to those of previously reported LICs and supercapacitors, which suggests that appropriately treated graphene can be a promising electrode material for LICs.