title: Redox Active Colloids as Discrete Energy Storage Carriers.
abstract: Versatile and readily available battery materials compatible with a range of electrode configurations and cell designs are desirable for renewable energy storage. Here we report a promising class of materials based on redox active colloids (RACs) that are inherently modular in their design and overcome challenges faced by small-molecule organic materials for battery applications, such as crossover and chemical/morphological stability. RACs are cross-linked polymer spheres, synthesized with uniform diameters between 80 and 800 nm, and exhibit reversible redox activity as single particles, as monolayer films, and in the form of flowable dispersions. Viologen-based RACs display reversible cycling, accessing up to 99% of their capacity and 99 ± 1% Coulombic efficiency over 50 cycles by bulk electrolysis owing to efficient, long-distance intraparticle charge transfer. Ferrocene-based RACs paired with viologen-based RACs cycled efficiently in a nonaqueous redox flow battery employing a simple size-selective separator, thus demonstrating a possible application that benefits from their colloidal dimensions. The unprecedented versatility in RAC synthetic and electrochemical design opens new avenues for energy storage.
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Elena C
authors.initials: EC
authors.lastname: Montoto
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Gavvalapalli
authors.initials: G
authors.lastname: Nagarjuna
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Jingshu
authors.initials: J
authors.lastname: Hui
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Mark
authors.initials: M
authors.lastname: Burgess
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Nina M
authors.initials: NM
authors.lastname: Sekerak
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hernández-Burgos
authors.affiliation: Joint Center for Energy Storage Research , United States.|Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Teng-Sing
authors.initials: TS
authors.lastname: Wei
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Marissa
authors.initials: M
authors.lastname: Kneer
authors.affiliation: Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Joshua
authors.initials: J
authors.lastname: Grolman
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Cheng
authors.affiliation: Joint Center for Energy Storage Research , United States.|Paulson School of Engineering and Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Lewis
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.|Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Moore
authors.affiliation: Joint Center for Energy Storage Research , United States.|Department of Chemistry, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Rodríguez-López