title: Hybrid supercapacitor-battery materials for fast electrochemical charge storage.
abstract: High energy and high power electrochemical energy storage devices rely on different fundamental working principles--bulk vs. surface ion diffusion and electron conduction. Meeting both characteristics within a single or a pair of materials has been under intense investigations yet, severely hindered by intrinsic materials limitations. Here, we provide a solution to this issue and present an approach to design high energy and high power battery electrodes by hybridizing a nitroxide-polymer redox supercapacitor (PTMA) with a Li-ion battery material (LiFePO4). The PTMA constituent dominates the hybrid battery charge process and postpones the LiFePO4 voltage rise by virtue of its ultra-fast electrochemical response and higher working potential. We detail on a unique sequential charging mechanism in the hybrid electrode: PTMA undergoes oxidation to form high-potential redox species, which subsequently relax and charge the LiFePO4 by an internal charge transfer process. A rate capability equivalent to full battery recharge in less than 5 minutes is demonstrated. As a result of hybrid's components synergy, enhanced power and energy density as well as superior cycling stability are obtained, otherwise difficult to achieve from separate constituents.
authors.affiliation: Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Electrical Engineering, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Vlad
authors.affiliation: Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, United States.
authors.forename: N
authors.initials: N
authors.lastname: Singh
authors.affiliation: Institute of Condensed Matter and Nanosciences, Bio- and Soft Matter, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Rolland
authors.affiliation: Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Electrical Engineering, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Melinte
authors.affiliation: Department of Mechanical Engineering and Materials Science, Rice University, Houston, Texas 77005, United States.
authors.forename: P M
authors.initials: PM
authors.lastname: Ajayan
authors.affiliation: Institute of Condensed Matter and Nanosciences, Bio- and Soft Matter, Université catholique de Louvain, Louvain la Neuve, B-1348 Belgium.
authors.forename: J-F
authors.initials: JF
authors.lastname: Gohy