Sodium-ion batteries (SIBs) have been proposed as a potential substitute for commercial lithium-ion batteries due to their excellent storage performance and cost-effectiveness. However, due to the substantial radius of sodium ions, there is an urgent need to develop anode materials with exemplary electrochemical characteristics, thereby enabling the fabrication of sodium-ion batteries with high energy density and rapid dynamics. Carbon materials are highly valued in the energy-storage field due to their diverse structures, low cost, and high reliability. This review comprehensively summarizes the typical structure; energy-storage mechanisms; and current development status of various carbon-based anode materials for SIBs, such as hard carbon, soft carbon, graphite, graphene, carbon nanotubes (CNTs), and porous carbon materials. This review also provides an overview of the current status and future development of related companies for sodium-ion batteries. Furthermore, it offers a summary and outlook on the challenges and opportunities associated with the design principles and large-scale production of carbon materials with high-energy-density requirements. This review offers an avenue for exploring outstanding improvement strategies for carbon materials, which can provide guidance for future application and research.

Rechargeable Li-O₂ batteries (LOBs) have been receiving intensive attention because of their ultra-high theoretical energy density close to the gasoline. Herein, Ag modified urchin-like α-MnO₂ (Ag-MnO₂) material with hierarchical porous structure is obtained by a facile one-step hydrothermal method. Ag-MnO₂ possesses thick nanowires and presents hierarchical porous structure of mesopores and macropores. The unique structure can expose more active sites, and provide continuous pathways for O₂ and discharge products as well. The doping of Ag leads to the change of electronic distribution in a-MnO₂ (i.e., more oxygen vacancies), which play important roles in improving their intrinsic catalytic activity and conductivity. As a result, LOBs with Ag-MnO₂ catalysts exhibit lower overpotential, higher discharge specific capacity and much better cycle stability compared to pure α-MnO₂. LOBs with Ag-MnO₂ catalysts exhibit a superior discharge specific capacity of 13,131 mAhg⁻¹ at a current density of 200 mAg⁻¹, a good cycle stability of 500 cycles at the capacity of 500 mAhg⁻¹. When current density is increased to 400 mAg⁻¹, LOBs still retain a long lifespan of 170 cycles at a limited capacity of 1,000 mAhg⁻¹.

Catalytic processes are the dominant driving force in the chemical industry, proper design and fabrication of three-dimensional (3D) catalysts monoliths helps to keep the active species from scattering in the reaction flow, improve high mass loading, expose abundant active catalytic sites and even realize turbulent gas flow, greatly improving the catalytic performance. Three-dimensional printing technology, also known as additive manufacturing, provides free design and accurate fabrication of complex 3D structures in an efficient and economic way. This disruptive technology brings light to optimizing and promoting the development of existing catalysts. In this mini review, we firstly introduce various printing techniques which are applicable for fabricating catalysts. Then, the recent developments in 3D printing catalysts are scrutinized. Finally, challenges and possible research directions in this field are proposed, with the expectation of providing guidance for the promotion of 3D printed catalysts.