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Focusing on Relevant Features Governing the Electrochemical Behavior of Li (4‐ x )/3 Ti (5‐2 x )/3 Cr x O 4 Electrode Material
Author(s) -
ÁlvarezSerrano Inmaculada,
López María Luisa,
RodríguezAguado Elena,
RodríguezCastellón Enrique,
Pico Carlos
Publication year - 2018
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201800333
Subject(s) - electrochemistry , microstructure , titanium , spinel , lithium (medication) , materials science , dielectric spectroscopy , amorphous solid , electrode , analytical chemistry (journal) , aqueous solution , diffusion , phase (matter) , oxide , chromium , inorganic chemistry , chemistry , metallurgy , crystallography , medicine , physics , organic chemistry , chromatography , thermodynamics , endocrinology
Two sets of the spinel‐type compounds Li (4‐ x )/3 Ti (5‐2 x )/3 Cr x O 4 (LTCO) with x =0, 0.1, and 0.2 were prepared from two synthetic strategies implying different precursors (freshly obtained titanium glycolate and amorphous hydrated titanium oxide). These routes allowed to synthesize samples with high purity (for x =0.2) and significant different microstructure. Structural and compositional characterization revealed the existence of an atomic percentage of 0.08 Cr 6+ cations at the tetrahedral sites of the spinel‐type structure. Concomitantly, the corresponding amount of Ti 3+ cations is stabilized. The electrochemical response is evaluated in LTCO‐composites materials fabricated with environmentally friendly sodium alginate as a binder. The phase with x =0.2 prepared from the glycolate precursor at a temperature as low as 600 °C shows good electrochemical performance. Thus, capacity values greater than 200 mA h g −1 at 0.5C are related to an increase in the value of lithium‐ion diffusion coefficient (ca. 2.67×10 −12 cm 2 s −1 , as estimated from electrochemical impedance spectroscopy, EIS). Furthermore, when this electrode is cycled at high density current rates (2C), discharge capacity values of ∼125 mA h g −1 are obtained, which means a retention of 63 and 52 % in the cycles 700 th and 1000 th , respectively. The remarkable electrochemical response displayed is interpreted considering different concurrent features: an appropriate microstructure, an aqueous binder, and the stabilization of mixed‐valent titanium (Ti 4+ /Ti 3+ ) and chromium (Cr 6+ /Cr 3+ ) cations at the surface.