Rechargeable sodium-ion batteries (SIBs), as the most promising alternative to commercial lithium-ion batteries, have received tremendous attention during the last decade. Among all the anode materials for SIBs, metal sulfides/selenides (MXs) have shown inspiring results because of their versatile material species and high theoretical capacity. They suffer from large volume expansion, however, which leads to bad cycling performance. Thus, methods such as carbon modification, nanosize design, electrolyte optimization, and cut-off voltage control are used to obtain enhanced performance. Here, recent progress on MXs is summarized in terms of arranging the crystal structure, synthesis methods, electrochemical performance, mechanisms, and kinetics. Challenges are presented and effective ways to solve the problems are proposed, and a perspective for future material design is also given. It is hoped that light is shed on the development of MXs to help finally find applications for next-generation rechargeable batteries.

Dou, S. X. (2013). Reduced graphene oxide with superior cycling stability and rate capability for sodium storage. Carbon, 57 ( June), 202-208. Reduced graphene oxide with superior cycling stability and rate capability for sodium storage AbstractSodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this communication, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1 M NaClO4 in propylene carbonate (PC). The experimental results show that the RGO anode allowed significant sodium ion insertion, leading to higher capacity at high current density compared to the previously reported results for carbon materials. This is due to the fact that RGO possesses higher electrical conductivity and is a more active host, with large interlayer distances and a disordered structure, enabling it to store a higher amount of Na ions. RGO anode exhibits high capacity combined with long-term cycling stability at high current densities, leading to reversible capacity as high as 174.3 mAh g-1 at 0.2 C (40 mA g-1), and even 93.3 mAh g-1 at 1 C (200 mA g-1) after 250 cycles. Furthermore, RGO could yield a high capacity of 141 mAh g-1 at 0.2 C (40 mA g-1) over 1000 cycles. AbstractThe sodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this paper, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1 M NaClO 4 in propylene carbonate (PC).The experimental results show that the RGO anode allowed significant sodium ion storage, leading to higher capacity at high current density compared to the previously reported results for carbon materials. This is due to the fact that RGO possesses higher electrical conductivity and is a more active host, with large interlayer distances and a disordered structure, enabling it to store a higher amount of Na ions. RGO anode exhibits high capacity combined with long-term cycling stability at high current densities, leading to reversible capacity as high as 174.3 mAh g -1 at 0.2 C (40 mA g -1 ), and even 93.3 mAh g -1 at 1 C (200 mA g -1 ) after 250 cycles. Furthermore, RGO could yield a high capacity of 141 mAh g -1 at 0.2 C (40 mA g -1 ) over 1000 cycles.

Sodium‐ion batteries (SIBs) have been considered as the most promising candidate for large‐scale energy storage system owing to the economic efficiency resulting from abundant sodium resources, superior safety, and similar chemical properties to the commercial lithium‐ion battery. Despite the long period of academic research, how to realize sodium‐ion battery commercialization for market applications is still a great challenge. Thus, from the perspective of future practical application, this review will identify the factors that are restricting commercialization, and evaluate the existing active materials and sodium‐ion‐based full‐cell system. The design and development trends that are needed for SIBs to meet the requirements of practical applications in large‐scale energy storage will also be discussed in detail.

Dou, S. (2013). Simply mixed commercial red phosphorus and carbon nanotube composite with exceptionally reversible sodium-ion storage. Nano Letters: a journal dedicated to nanoscience and nanotechnology, 13 (11), 5480-5484.Simply mixed commercial red phosphorus and carbon nanotube composite with exceptionally reversible sodium-ion storage AbstractRecently, sodium ion batteries (SIBs) have been given intense attention because they are the most promising alternative to lithium ion batteries for application in renewable power stations and smart grid, owing to their low cost, their abundant natural resources, and the similar chemistry of sodium and lithium. Elemental phosphorus (P) is the most promising anode materials for SIBs with the highest theoretical capacity of 2596 mA h g-1, but the commercially available red phosphorus cannot react with Na reversibly. Here, we report that simply hand-grinding commercial microsized red phosphorus and carbon nanotubes (CNTs) can deliver a reversible capacity of 1675 mA h g-1 for sodium ion batteries (SIBs), with capacity retention of 76.6% over 10 cycles. Our results suggest that the simply mixed commercial red phosphorus and CNTs would be a promising anode candidate for SIBs with a high capacity and low cost.Keywords ion, sodium, reversible, exceptionally, composite, storage, nanotube, simply, carbon, phosphorus, red, commercial, mixed Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsLi, W., Chou, S., Wang, J., Liu, H. & Dou, S. (2013). Simply mixed commercial red phosphorus and carbon nanotube composite with exceptionally reversible sodium-ion storage. Nano Letters: a journal dedicated to nanoscience and nanotechnology, 13 (11), 5480-5484. ABSTRACT: Recently, sodium ion batteries (SIBs) have been given intense attention because they are the most promising alternative to lithium ion batteries for application in renewable

Li and Na batteries are very important as energy storage devices for electric vehicles and smart grids. It is well known that, when an electrode is analysed in detail, each of the components (the active material, the conductive carbon, the current collector and the binder) makes a portion of contribution to the battery performance in terms of specific capacity, rate capability, cycle life, etc. However, there has not yet been a review on the binder, though there are already many review papers on the active materials. Binders make up only a small part of the electrode composition, but in some cases, they play an important role in affecting the cycling stability and rate capability for Li-ion and Na-ion batteries. Poly(vinylidene difluoride) (PVDF) has been the mainstream binder, but there have been discoveries that aqueous binders can sometimes make a battery perform better, not to mention they are cheaper, greener, and easier to use for electrode fabrication. In this review, we focus on several kinds of promising electrode materials, to show how their battery performance can be affected significantly by binder materials: anode materials such as Si, Sn and transitional metal oxides; cathode materials such as LiFePO4, LiNi1/3Co1/3Mn1/3O2, LiCoO2 and sulphur.