title: Graphene-modified LiFePO₄ cathode for lithium ion battery beyond theoretical capacity.
abstract: The specific capacity of commercially available cathode carbon-coated lithium iron phosphate is typically 120-160 mAh g(-1), which is lower than the theoretical value 170 mAh g(-1). Here we report that the carbon-coated lithium iron phosphate, surface-modified with 2 wt% of the electrochemically exfoliated graphene layers, is able to reach 208 mAh g(-1) in specific capacity. The excess capacity is attributed to the reversible reduction-oxidation reaction between the lithium ions of the electrolyte and the exfoliated graphene flakes, where the graphene flakes exhibit a capacity higher than 2,000 mAh g(-1). The highly conductive graphene flakes wrapping around carbon-coated lithium iron phosphate also assist the electron migration during the charge/discharge processes, diminishing the irreversible capacity at the first cycle and leading to ~100% coulombic efficiency without fading at various C-rates. Such a simple and scalable approach may also be applied to other cathode systems, boosting up the capacity for various Li batteries.
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: By
authors.initials: B
authors.lastname: Lung-Hao Hu
authors.forename: Feng-Yu
authors.initials: FY
authors.lastname: Wu
authors.forename: Cheng-Te
authors.initials: CT
authors.lastname: Lin
authors.forename: Andrei N
authors.initials: AN
authors.lastname: Khlobystov
authors.forename: Lain-Jong
authors.initials: LJ
authors.lastname: Li