Hierarchical NiCo₂O₄@NiMoO₄ core–shell nanowire/nanosheet arrays were successfully fabricated and assembled in an asymmetric supercapacitor device with outstanding electrochemical performance.

TiO₂-based materials have been widely studied in the field of photocatalysis, sensors, and solar cells. Besides that, TiO₂-based materials are of great interest for energy storage and conversion devices, in particular rechargeable lithium ion batteries (LIBs). TiO₂has significant advantage due to its low volume change (<4%) during Li ion insertion/desertions process, short paths for fast lithium ion diffusion, and large exposed surface offering more lithium insertion channels. However, the relatively low theoretical capacity and electrical conductivity of TiO₂greatly hampered its practical application. Various strategies have been developed to solve these problems, such as designing different nanostructured TiO₂to improve electronic conductivity, coating or combining TiO₂with carbonaceous materials, incorporating metal oxides to enhance its capacity, and doping with cationic or anionic dopants to form more open channels and active sites for Li ion transport. This review is devoted to the recent progress in enhancing the LIBs performance of TiO₂with various synthetic strategies and architectures control. Based on the lithium storage mechanism, we will also bring forward the existing challenges for future exploitation and development of TiO₂-based anodes in energy storage, which would guide the development for rationally and efficiently designing more efficient TiO₂-based LIBs anodes.

Transition metal selenides have emerged as a class of promising anodes for sodium ion batteries (SIBs). However, the notorious issues of their low electrical conductivity and huge volume changes during sodium ion insertion/extraction lead to poor cycling stability and inferior rate capability. In this work, hierarchically core–branched iron cobalt selenide arrays coated with N-doped carbon shell (denoted as FeCo–Se@NC) were rationally designed and synthesized on carbon cloth through a combined strategy of hydrothermal, selenization and carbonization processes. Benefitting from the designed arrays with simultaneous Fe doping into the CoSe₂ matrix and N-doped carbon coating, the optimized FeCo–Se@NC electrode possesses greatly enhanced structural integrity and accelerated ion/electron transfer kinetics. When employed as a binder- and additive-free anode for SIBs, the FeCo–Se@NC electrode exhibits a high reversible capacity of 532.1 mA h g⁻¹ at 0.05 A g⁻¹, competitive rate capability (193.3 mA h g⁻¹ at 5 A g⁻¹), and good cycling stability (386.1 mA h g⁻¹ after 150 cycles at 0.5 A g⁻¹). Moreover, when coupled with Na₃V₂(PO₄)₃/C, the full cell delivers a high capacity of 350.6 mA h g⁻¹ at 0.1 A g⁻¹ and a high energy density of 276.7 W h kg⁻¹. This work is expected to provide a new avenue for the development of arrayed transition metal selenide-based materials for high-performance SIBs.