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Deconvolving double-layer, pseudocapacitance, and battery-like charge-storage mechanisms in nanoscale LiMn2O4 at 3D carbon architectures.
- Source :
-
Electrochimica Acta . Jun2018, Vol. 275, p225-235. 11p. - Publication Year :
- 2018
-
Abstract
- Lithium manganese spinel, LiMn 2 O 4 (LMO), is a well-established active material for batteries, in which charge is stored via a two-stage insertion of Li + that manifests with coupled current peaks or voltage plateaus under voltammetric or galvanostatic conditions, respectively. The charge–discharge kinetics for LMO are significantly enhanced when the oxide is expressed in a nanoscale form, for example as an ultrathin coating of nanocrystallites at the surfaces of a 3D carbon substrate, such as fiber paper–supported carbon nanofoams (CNFs). In addition to expressing well-defined “battery-like” Li + -insertion peaks between ∼0.6 and 1 V vs . Ag/AgCl when cycled in aqueous lithium sulfate, LMO@CNF electrodes exhibit a pseudocapacitance envelop at more negative potentials (∼0.2–0.6 V). The pseudocapacitive character of LMO@CNF is further verified when cycled in aqueous sodium sulfate, where a broad capacitance envelop dominates the voltammetric response over the entire potential range at a current density an order of magnitude greater than expected for double-layer capacitance. Thus, the LMO@CNF electrode provides a prime example where multiple distinct charge-storage mechanisms are expressed in a single material. Herein, we apply voltammetry and impedance-based methods to deconvolve the respective contributions of double-layer capacitance, surface-based pseudocapacitance, and battery-like Li + insertion. The use of power-law analysis provides a general assignment of transport dynamics, while projecting impedance data as 3D Bode-style representations provides key mechanistic information regarding the time/frequency–potential response of LMO@CNF electrodes. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00134686
- Volume :
- 275
- Database :
- Academic Search Index
- Journal :
- Electrochimica Acta
- Publication Type :
- Academic Journal
- Accession number :
- 129521268
- Full Text :
- https://doi.org/10.1016/j.electacta.2018.04.149