Elucidating the charge storage mechanism of carbonaceous and organic electrode materials for sodium ion batteries

All-Graphene Quantum Dot-Derived Battery: Regulating Redox Activity Through Localized Subdomains

In the quest for materials sustainability for grid-scale applications, graphene quantum dot (GQD), prepared via eco-efficient processes, is one of the promising graphitic-organic matters that have the potential to provide greener solutions for replacing metal-based battery electrodes. However, the utilization of GQDs as electroactive materials has been limited; their redox behaviors associated with the electronic bandgap property from the sp2 carbon subdomains, surrounded by functional groups, are yet to be understood. Here, the experimental realization of a subdomained GQD-based anode with stable cyclability over 1000 cycles, combined with theoretical calculations, enables a better understanding of the decisive impact of controlled redox site distributions on battery performance. The GQDs are further employed in cathode as a platform for full utilization of inherent electrochemical activity of bio-inspired redox-active organic motifs, phenoxazine. Using the GQD-derived anode and cathode, an all-GQD battery achieves a high energy density of 290 Wh kgcathode -1 (160 Wh kgcathode+anode -1 ), demonstrating an effective way to improve reaction reversibility and energy density of sustainable, metal-free batteries.

Hybrid CuSn nanosphere-functionalized Cu/Sn co-doped hollow carbon nanofibers as anode materials for sodium-ion batteries

To strengthen the electrochemical performance of anode materials for sodium-ion batteries, Cu/Sn co-doped hollow carbon nanofibers functionalized by hybrid CuSn nanospheres (CuSn/C@MCNF) were prepared by a simple electrospinning method. The microstructural characteristics of CuSn/C@MCNF confirmed the same doped elements and strong interactions in hybrid CuSn nanospheres and the hollow carbon nanofiber substrate. CuSn/C@MCNF has superior specific capacity, excellent conductivity and high cycling stability. In particular, the doped hollow carbon nanofiber substrate can facilitate Na+ transport and alleviate volume expansion during the process of sodium storage. When applied as an anode material for sodium-ion batteries, CuSn/C@MCNF can deliver a reversible capacity of 340.1 mA h g-1 at a large current density of 1 A g-1 for 1000 cycles and a high-rate capacity of 202.5 mA h g-1 at 4.0 A g-1, all superior to the corresponding Sn-SnOx@MCNF- and MCNF-based electrodes. This work provides a basic idea for future anode materials in high-performance sodium-ion batteries.

A high areal capacity sodium-ion battery anode enabled by a free-standing red phosphorus@N-doped graphene/CNTs aerogel

A novel and facile strategy for fabricating red phosphorus@nitrogen doped graphene/carbon nanotube aerogel (P@NGCA) is proposed as a free-standing anode for high energy sodium-ion batteries. Owing to an optimized structure of red P uniformly confined in porous NGCA with high conductivity and mechanical stability, the free-standing P@NGCA anode exhibits outstanding sodium storage performance with a high areal capacity of 3.3 mA h cm^-2 and superior initial Coulombic efficiency of 80%.

Recent Advances in Biomass-Derived Carbon Materials for Sodium-Ion Energy Storage Devices

Compared with currently prevailing Li-ion technologies, sodium-ion energy storage devices play a supremely important role in grid-scale storage due to the advantages of rich abundance and low cost of sodium resources. As one of the crucial components of the sodium-ion battery and sodium-ion capacitor, electrode materials based on biomass-derived carbons have attracted enormous attention in the past few years owing to their excellent performance, inherent structural advantages, cost-effectiveness, renewability, etc. Here, a systematic summary of recent progress on various biomass-derived carbons used for sodium-ion energy storage (e.g., sodium-ion storage principle, the classification of bio-microstructure) is presented. Current research on the design principles of the structure and composition of biomass-derived carbons for improving sodium-ion storage will be highlighted. The prospects and challenges related to this will also be discussed. This review attempts to present a comprehensive account of the recent progress and design principle of biomass-derived carbons as sodium-ion storage materials and provide guidance in future rational tailoring of biomass-derived carbons.

Sulfonated polybenzothiazole cathode materials for Na-ion batteries

A new flexible aromatic polymer sulfonated polybenzothiazole (sPBT-SE) with sulphone and ether units is reported as an advanced cathode material for storing Na+, which delivers a high discharge capacity of 103 mA h g−1 after 350 cycles at 30 mA g−1.