Due to massively growing demand arising from energy storage systems, sodium ion batteries (SIBs) have been recognized as the most attractive alternative to the current commercialized lithium ion batteries (LIBs) owing to the wide availability and accessibility of sodium. Unfortunately, the low energy density, inferior power density and poor cycle life are still the main issues for SIBs in the current drive to push the entire technology forward to meet the benchmark requirements for commercialization. Over the past few years, tremendous efforts have been devoted to improving the performance of SIBs, in terms of higher energy density and longer cycling lifespans, by optimizing the electrode structure or the electrolyte composition. In particular, among the established anode systems, those materials, such as metals/alloys, phosphorus/phosphides, and metal oxides/sulfides/selenides, that typically deliver high theoretical sodium-storage capacities have received growing interest and achieved significant progress. Although some review articles on electrodes for SIBs have been published already, many new reports on these anode materials are constantly emerging, with more promising electrochemical performance achieved via novel structural design, surface modification, electrochemical performance testing techniques, etc. So, we herein summarize the most recent developments on these high-performance anode materials for SIBs in this review. Furthermore, the different reaction mechanisms, the challenges associated with these materials, and effective approaches to enhance performance are discussed. The prospects for future high-energy anodes in SIBs are also discussed.

Sodium-ion batteries (SIBs) have attracted great attention recently due to the abundance of sodium resources, particularly for large-scale electric energy storage applications for renewable energy and smart grids. More and more nanostructured anode materials have been developed with the aims of high energy density, high cycling stability, and excellent rate capability, in which two-dimensional (2D) nanostructures are showing promise due to their shortened paths for sodium ion transportation and larger surface areas for sodium ion absorption. Moreover, 2D materials (e.g. graphene) have been proved to be excellent supporting and conducting agents in SIB anodes due to their high electrical conductivity and structural stability, in which synergetic effects between the graphene and the active materials are generally observed. This review is devoted to the recent progress in the use of 2D active materials and in composites consisting of both 2D supports and active materials as anodes for SIBs. Based on the manner of sodium storage, their electrochemical performance for sodium storage is discussed in terms of four classifications, including carbonaceous materials (graphene and carbon nanosheets), alloy based materials (Sn, Sb, and P), conversion materials (phosphides/oxides/sulfides/selenides), and intercalation materials (Ti-based compounds). Finally, the main challenges for and perspectives on 2D nanostructures for sodium storage are discussed.

Surface amorphization provides unprecedented opportunities for altering and tuning material properties. Surface‐amorphized TiO₂@graphene synthesized using a designed low temperature‐phase transformation technique exhibits significantly improved rate capability compared to well‐crystallized TiO₂@graphene and bare TiO₂ electrodes. These improvements facilitates lithium‐ion transport in both insertion and extraction processes and enhance electrolyte absorption capability.