Abstract
•Cobalt-doped anatase.•Diffusion-controlled mechanism.•Synchrotron X-ray absorption.•Pseudocapacitive behavior.
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The effective diffusion-controlled performance of the SIB anode, CoxTi1−xO2/CNTs, presented here offers high reversible sodium uptake. Kinetic studies of the samples conducted through cyclic voltammetry at various scan rates suggest that by increasing the mass ratio of Co atoms in TiO2 lattice the mechanism is shifted from a slow diffusive charge contribution to a fast capacitive charge contribution. Partial amorphization of the crystalline TiO2 diffraction planes revealed by ex-situ XRD along with the attenuation of the crystal lattice reflects the ability of the electrodes for high reversible sodium uptake. The synchronous effect of CNTs and Co loading enhance the porosity with multiple electronic/ionic conducting channels favouring high sodium storage and stability from 109.3 mAh g–1 in TiO2 to 168.5 mAh g–1 in Co0.03Ti0.97O2/CNT electrode after 80 cycles at a current rate of 0.05 C.