Abstract
AbstractTiO2 is a promising material for high‐power battery and supercapacitor applications. However, in general TiO2 suffers from an initial irreversible capacity that limits its use in different applications. A combination of a microbead morphology, Nb‐doping, and the use of an ionic liquid electrolyte is shown to significantly decrease the irreversible capacity loss. A change in the electrochemical response in the first cycles indicates formation of a solid–electrolyte interphase (SEI) or a modification of the structure of the surface layer of the TiO2/Nb microbeads, which apparently stabilises the performance. The change in the response is manifested in an increased charge transfer resistance and the presence of two charge transfer contributions. During prolonged cycling the TiO2/Nb electrode shows an excellent stability over 5000 cycles. Ex situ analysis after cycling shows that the overall microbead morphology is intact and that there are no changes in the crystal structure. However, a decrease in the intensity of the XRD pattern can point to a decrease in size of the nanocrystals building up the microbeads or the formation of amorphous phases.
Highlights
TiO2 has been studied extensively for its high-power performance in batteries[3,4] as well as in hybrid supercapacitors.[5]
We have recently reported on a new route to achieve high power-performance and good cycling stability by a microbead morphology of anatase TiO2.[23]. Another route that can be explored is doping by aliovalent ions to tune the electronic properties of anatase and a few studies have been reported on doping TiO2 with Nb5 +.[24,25]
There is a clear influence of Nb on the charge transfer process which could be related to the difference cohesive energies between the two phases LiTi2O4 and LiNb2O4[37,38] and thermodynamically infers that the Nb-doped structure is less stable and more subject to accepting structure changes such as Li + intercalation
Summary
TiO2 has been studied extensively for its high-power performance in batteries[3,4] as well as in hybrid supercapacitors.[5]. Li and TiO2 at higher potentials.[7] Overall the Li-insertion and extraction mechanism can be described by [Eq (1)]: Supercapacitors can play an important role in future energy systems in parallel with Li-ion batteries.[1] Compared to batteries, supercapacitors possess higher power density, longer cycle lifetime, lower cost of active materials and increased safety.[2] supercapacitors are hampered by comparatively low energy densities. Li-insertion[32] or different parasitic reactions at the surface, restricting lithium diffusion.[33] The rather low irreversible capacity losses for our materials indicate that the microbeads. In particular we target the electrochemical response of the material, the effect on irreversible capacity loss, and the role of Nb-doping in stabilizing and improving the cycling performance
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
