Yongjin Fang

Hierarchical carbon framework wrapped Na3V2(PO4)3 as a superior high-rate and extended lifespan cathode for sodium-ion batteries.

Hierarchical carbon framework wrapped Na3 V2 (PO4 )3 (HCF-NVP) is successfully synthesized through chemical vapor deposition on pure Na3 V2 (PO4 )3 particles. Electrochemical experiments show that the HCF-NVP electrode can deliver a large reversible capacity (115 mA h g(-1) at 0.2 C), superior high-rate rate capability (38 mA h g(-1) at 500 C), and ultra-long cycling stability (54% capacity retention after 20 000 cycles).

Mesoporous Amorphous FePO4 Nanospheres as High-Performance Cathode Material for Sodium-Ion Batteries

FePO4 nanospheres are synthesized successfully through a simple chemically induced precipitation method. The nanospheres present a mesoporous amorphous structure. Electrochemical experiments show that the FePO4/C electrode demonstrates a high initial discharging capacity of 151 mAh g(-1) at 20 mA g(-1), stable cyclablilty (94% capacity retention ratio over 160 cycles), as well as high rate capability (44 mAh g(-1) at 1000 mA g(-1)) for Na-ion storage. The superior electrochemical performance of the FePO4/C nanocomposite is due to its particular mesoporous amorphous structure and close contact with the carbon framework, which significantly improve the ionic and electronic transport and intercalation kinetics of Na ions.

Phosphate Framework Electrode Materials for Sodium Ion Batteries

Sodium ion batteries (SIBs) have been considered as a promising alternative for the next generation of electric storage systems due to their similar electrochemistry to Li‐ion batteries and the low cost of sodium resources. Exploring appropriate electrode materials with decent electrochemical performance is the key issue for development of sodium ion batteries. Due to the high structural stability, facile reaction mechanism and rich structural diversity, phosphate framework materials have attracted increasing attention as promising electrode materials for sodium ion batteries. Herein, we review the latest advances and progresses in the exploration of phosphate framework materials especially related to single‐phosphates, pyrophosphates and mixed‐phosphates. We provide the detailed and comprehensive understanding of structure–composition–performance relationship of materials and try to show the advantages and disadvantages of the materials for use in SIBs. In addition, some new perspectives about phosphate framework materials for SIBs are also discussed. Phosphate framework materials will be a competitive and attractive choice for use as electrodes in the next‐generation of energy storage devices.

High-Performance Olivine NaFePO4 Microsphere Cathode Synthesized by Aqueous Electrochemical Displacement Method for Sodium Ion Batteries

Olivine NaFePO4/C microsphere cathode is prepared by a facile aqueous electrochemical displacement method from LiFePO4/C precursor. The NaFePO4/C cathode shows a high discharge capacity of 111 mAh g(-1), excellent cycling stability with 90% capacity retention over 240 cycles at 0.1 C, and high rate capacity (46 mAh g(-1) at 2 C). The excellent electrochemical performance demonstrates that the aqueous electrochemical displacement method is an effective and promising way to prepare NaFePO4/C material for Na-based energy storage applications. Moreover, the Na2/3FePO4 intermediate is observed for the first time during the Na intercalation process through conventional electrochemical techniques, corroborating an identical two-step phase transition reaction both upon Na intercalation and deintercalation processes. The clarification of the electrochemical reaction mechanism of olivine NaFePO4 could inspire more attention on the investigation of this material for Na ion batteries.

Graphene-Scaffolded Na3V2(PO4)3 Microsphere Cathode with High Rate Capability and Cycling Stability for Sodium Ion Batteries

High voltage, high rate, and cycling-stable cathodes are urgently needed for development of commercially viable sodium ion batteries (SIBs). Herein, we report a facile spray-drying method to synthesize graphene-scaffolded Na3V2(PO4)3 microspheres (NVP@rGO), in which nanocrystalline Na3V2(PO4)3 is embedded in graphene sheets to form porous microspheres. Benefiting from the highly conductive graphene framework and porous structure, the NVP@rGO material exhibits a high reversible capacity (115 mAh g-1 at 0.2 C), long-term cycle life (81% of capacity retention up to 3000 cycles at 5 C), and excellent rate performance (44 mAh g-1 at 50 C). The electrochemical properties of a full Na-ion cell with the NVP@rGO cathode and Sb/C anode are also investigated. The present results suggest promising applications of the NVP@rGO material as a high performance cathode for sodium ion batteries.

Recent Progress in Iron-Based Electrode Materials for Grid-Scale Sodium-Ion Batteries

Grid-scale energy storage batteries with electrode materials made from low-cost, earth-abundant elements are needed to meet the requirements of sustainable energy systems. Sodium-ion batteries (SIBs) with iron-based electrodes offer an attractive combination of low cost, plentiful structural diversity and high stability, making them ideal candidates for grid-scale energy storage systems. Although various iron-based cathode and anode materials have been synthesized and evaluated for sodium storage, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this Review, progress in iron-based electrode materials for SIBs, including oxides, polyanions, ferrocyanides, and sulfides, is briefly summarized. In addition, the reaction mechanisms, electrochemical performance enhancements, structure-composition-performance relationships, merits and drawbacks of iron-based electrode materials for SIBs are discussed. Such iron-based electrode materials will be competitive and attractive electrodes for next-generation energy storage devices.

Recent Advances in Sodium-Ion Battery Materials

Grid-scale energy storage systems with low-cost and high-performance electrodes are needed to meet the requirements of sustainable energy systems. Due to the wide abundance and low cost of sodium resources and their similar electrochemistry to the established lithium-ion batteries, sodium-ion batteries (SIBs) have attracted considerable interest as ideal candidates for grid-scale energy storage systems. In the past decade, though tremendous efforts have been made to promote the development of SIBs, and significant advances have been achieved, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this review, the latest progress in electrode materials for SIBs, including a variety of promising cathodes and anodes, is briefly summarized. Besides, the sodium storage mechanisms, endeavors on electrochemical property enhancements, structural and compositional optimizations, challenges and perspectives of the electrode materials for SIBs are discussed. Though enormous challenges may lie ahead, we believe that through intensive research efforts, sodium-ion batteries with low operation cost and longevity will be commercialized for large-scale energy storage application in the near future.Graphical Abstract