Electrode materials with macroporous structures have desirable structural advantages, which can provide excellent reaction sites for electrons and ions. In this study, a novel macroporous nanostructure is synthesized utilizing N-doped hollow carbon spheres and ZIF-67 derived Co₉S₈ embedded in graphene (GH@NC@Co₉S₈). This macroporous nanostructure can maximize the entire surface area, which provides a favorable transport environment for the electrons and ions of the electrolyte. Furthermore, in situ grown Co₉S₈ polyhedra derived from ZIF-67 can improve the reactivity and specific capacity of the composite due to their amorphous phase and hollow three-dimensional structure. The as-prepared GH@NC@Co₉S₈ acts as a binder-free electrode for supercapacitors; it shows a high volumetric capacitance of 842.4 F cm⁻³ at a current density of 1 A g⁻¹. An asymmetric supercapacitor fabricated with GH@NC@Co₉S₈ (positive electrode) and GH@NC (negative electrode) shows a superb volumetric energy density of 28.7 W h L⁻¹ at a high power density of 971.9 W L⁻¹ and long cycle life (95.8% capacity retention after 8000 cycles). This device has great practical value in electrochemical energy storage.

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.