Core-shell engineering of titanium-based anodes toward enhanced electrochemical lithium/sodium storage performance: a review

Titanium-based materials, including titanium dioxide, alkali-titanium oxides, titanium phosphates/oxyphosphates, titanium-based MXenes, and some other complex titanium compounds, have been regarded as promising anode candidates for Li/Na ion batteries, due to their advantages of good stability, high safety, low cost, and easy synthesis. However, poor electrical conductivity, high work potential, and low output capacity largely hinder the practical applications. Core-shell structure has been widely reported as an effective way to address these problems, and tremendous efforts have been made toward this direction. In this review, we offer an overview of core-shell titanium-based anode engineering for highly efficient and stable Li/Na ion batteries. The review presents the recent progresses and challenges in materials discovery, structure design, and electrode engineering, and highlights the advantages and drawbacks of a series of core-shell engineering strategies. In detail, the material structure, morphology, and composition of various core-shell nanocomposites are reviewed; the structure-activity-stability relationship between core-shell electrodes and electrochemical properties is discussed; the effective strategies for core-shell engineering are summarized, and the development prospects of titanium-based anodes are proposed. We anticipate that this review could provide a systematic understanding of core-shell engineering design of high-performance titanium-based anodes.