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Evidence of a Pseudo‐Capacitive Behavior Combined with an Insertion/Extraction Reaction Upon Cycling of the Positive Electrode Material P2‐Na x Co 0.9 Ti 0.1 O 2 for Sodium‐ion Batteries
Author(s) -
Sabi Noha,
Sarapulova Angelina,
Indris Sylvio,
Dsoke Sonia,
Zhao Zijian,
Dahbi Mouad,
Ehrenberg Helmut,
Saadoune Ismael
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201801870
Subject(s) - materials science , intercalation (chemistry) , electrochemistry , dielectric spectroscopy , electrode , sodium , synchrotron , analytical chemistry (journal) , alkali metal , titanium , cobalt , inorganic chemistry , chemistry , metallurgy , physics , organic chemistry , chromatography , nuclear physics
Layered oxides are promising materials due to their easy diffusion path for alkali metals. Specifically, Na x CoO 2 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 Na x Co 0.9 Ti 0.1 O 2 , 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 Na x CoO 2 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 Na x Co 0.9 Ti 0.1 O 2 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.