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- Title
Evidence of a Pseudo‐Capacitive Behavior Combined with an Insertion/Extraction Reaction Upon Cycling of the Positive Electrode Material P2‐Na<sub>x</sub>Co<sub>0.9</sub>Ti<sub>0.1</sub>O<sub>2</sub> for Sodium‐ion Batteries.
- Authors
Sabi, Noha; Sarapulova, Angelina; Indris, Sylvio; Dsoke, Sonia; Zhao, Zijian; Dahbi, Mouad; Ehrenberg, Helmut; Saadoune, Ismael
- Abstract
Layered oxides are promising materials due to their easy diffusion path for alkali metals. Specifically, NaxCoO2 can be regarded as an appealing candidate for next‐generation sodium‐ion batteries (SIBs), but the multiple steps revealed in the potential vs capacity curve have restricted its use. Herein, we report NaxCo0.9Ti0.1O2, synthesized by a high‐temperature solid‐state method, where 10 % of cobalt was substituted with titanium. Obviously, the number of potential steps found in the galvanostatic curves of NaxCoO2 has been reduced. The electrode material exhibits an initial charge capacity of 108 mAh/g within the potential window 2–4.2 V (vs. Na+/Na). The intercalation/deintercalation of NaxCo0.9Ti0.1O2 was investigated by in situ synchrotron X‐ray diffraction (SXRD), and the results demonstrated a combined solid solution and pseudocapacitive mechanism, where the pseudocapacitive behavior is predominant in the region from 3.73 V (charge) to 3.79 V (discharge). Finally, in situ electrochemical impedance spectroscopy has revealed an increasing impedance, specifically when inserting sodium into the structure. Electrode materials: P2‐Na0.66Co0.9Ti0.1O2 is synthesized by a solvent‐free, solid‐state method. The material exhibits an initial charge capacity of 108 mAh/g in the voltage range of 2–4.2 V. Including 10 % titanium stabilizes the structure (within the studied potential window) and reduces the number of steps revealed for NaxCoO2. The positive electrode material demonstrates a pseudocapacitive behavior and an exceptional rate capability at 5 C.
- Subjects
ALKALI metals; STORAGE batteries; SYNCHROTRONS; X-ray diffraction; COBALT
- Publication
ChemElectroChem, 2019, Vol 6, Issue 3, p892
- ISSN
2196-0216
- Publication type
Article
- DOI
10.1002/celc.201801870