3D Hierarchical Micro/Nanostructures for Sodium-Based Battery Anode Materials

To meet the increasing energy demand, the development of rechargeable batteries holds immense potential to extend the limitations of electrochemical performance in energy storage devices and enhances the economic efficiency of the energy storage market. Sodium-based batteries have gained tremendous attention in recent years as a potential alternative to reduce the supply risks concerned with lithium-ion batteries (LIBs) owing to the cost-effectiveness and abundance of sodium resources in earth. However, it is still limited by the large ionic radius of Na+ and heavy sodium atoms, which lead to a short cycle life and low energy/power density caused by the sluggish reaction kinetics. A pivotal factor in propelling the commercialization of sodium-based batteries lies in the exploration of advanced anode materials that ideally offer increased mass loading, superior energy/power density, and enhanced conductivity. Three-dimensional hierarchical micro/nanostructured (3D-HMNs) materials have achieved significant research interest since they have played a crucial role in improving the performance of sodium-based cells. They have numerous active sites, versatile functionalization, and favorable transport distances for mass/electron, as well as superior electrochemical performances, which are correlated with the nature of structures and composition. In this Account, we mainly provide an overview of our recent research advancements in the utilization of 3D-HMN anode materials in various sodium-based rechargeable batteries, shedding light on the relationship between structure and performance. We commence by presenting tailored synthetic methodologies for creating 3D-HMNs, which encompass template-assisted strategies (hard template, soft template, self-sacrificing template, etc.), electrospinning methods, and 3D printing technologies. Here, the process, structure, advantages/disadvantages of the three synthetic strategies for preparing 3D-HMNs are detailed. Our emphasis is placed on the resulting superstructures, which range from nanoflowers, cuboid-like structures, nanosheets, and nanowires to hierarchical fiber arrangements. We then illustrate the essential advantages made with these materials in a range of sodium-based batteries, covering conventional sodium ion batteries (SIBs), sodium-chalcogen (Na-S, Na-Se, Na-Te) batteries, sodium-based dual-ion batteries (SDIBs), and the corresponding sodium ion hybrid capacitors (SIHCs). The applications of 3D-HMNs in all the sodium-based battery systems are comprehensively discussed, including rational structural design and optimization, microscopic electronic properties, and electrochemical performance. Lastly, we outline the challenges ahead in our endeavor, potential solutions, and future research directions to enhance the performance of 3D-HMNs in sodium-based batteries. It is hoped that this Account will provide some valuable guidelines for rational anode materials design, balancing excellent capacity and fast ion transport, and meanwhile advance the development of sodium energy storage.