title: Asymmetric pathways in the electrochemical conversion reaction of NiO as battery electrode with high storage capacity.
abstract: Electrochemical conversion reactions of transition metal compounds create opportunities for large energy storage capabilities exceeding modern Li-ion batteries. However, for practical electrodes to be envisaged, a detailed understanding of their mechanisms is needed, especially vis-à-vis the voltage hysteresis observed between reduction and oxidation. Here, we present such insight at scales from local atomic arrangements to whole electrodes. NiO was chosen as a simple model system. The most important finding is that the voltage hysteresis has its origin in the differing chemical pathways during reduction and oxidation. This asymmetry is enabled by the presence of small metallic clusters and, thus, is likely to apply to other transition metal oxide systems. The presence of nanoparticles also influences the electrochemical activity of the electrolyte and its degradation products and can create differences in transport properties within an electrode, resulting in localized reactions around converted domains that lead to compositional inhomogeneities at the microscale.
authors.affiliation: 1] Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA [2] Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Boesenberg
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Marcus
authors.affiliation: Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Alpesh K
authors.initials: AK
authors.lastname: Shukla
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
authors.forename: Tanghong
authors.initials: T
authors.lastname: Yi
authors.affiliation: Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Eamon
authors.initials: E
authors.lastname: McDermott
authors.affiliation: 1] Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA [2] School of Materials Science and Engineering, Nanyang Technological University, Singapore.
authors.forename: Pei Fen
authors.initials: PF
authors.lastname: Teh
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore.
authors.forename: Madhavi
authors.initials: M
authors.lastname: Srinivasan
authors.affiliation: Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Alexander
authors.initials: A
authors.lastname: Moewes
authors.affiliation: 1] Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA [2] Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA.
authors.forename: Jordi
authors.initials: J
authors.lastname: Cabana
mesh_terms: D011211:Electric Power Supplies; D004560:Electricity; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D008094:Lithium / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D012993:Solar Energy / Q000706:statistics & numerical data*
chemical_list: D009532:Nickel; D008094:Lithium; C028007:nickel monoxide