Sodium ion batteries are attractive for the rapidly emerging large‐scale energy storage market for intermittent renewable resources. Currently a viable cathode material does not exist for practical non‐aqueous sodium ion battery applications. Here we disclose a high performance, durable electrode material based on the 3D NASICON framework. Porous Na3V2(PO4)3/C was synthesized using a novel solution‐based approach. This material, as a cathode, is capable of delivering an energy storage capacity of ∼400 mWh/g vs. sodium metal. Furthermore, at high current rates (10, 20 and 40 C), it displayed remarkable capacity retention. Equally impressive is the long term cycle life. Nearly 50% of the initial capacity was retained after 30,000 charge/discharge cycles at 40 C (4.7 A/g). Notably, coulombic efficiency was 99.68% (average) over the course of cycling. To the best of our knowledge, the combination of high energy density, high power density and ultra long cycle life demonstrated here has never been reported before for sodium ion batteries. We believe our findings will have profound implications for developing large‐scale energy storage systems for renewable energy sources.

We report here the electrochemical properties of Na 2 Ti 3 O 7 , a potential non-carbon based, low-voltage anode material for room temperature sodium ion battery applications. A solid-state route was used to prepare Na 2 Ti 3 O 7 . Further, XRD, SEM, TEM, HRTEM, SAED, XPS and EDX techniques were used to characterize the material. The Na/Na 2 Ti 3 O 7 cell displayed a charge capacity of 177 mA h g À1 at 0.1 C rate. High rate and long term cyclic performance at different rates showed relatively stable storage capacities. Surprisingly, if the lower cut-off voltage is altered, the appearance of a new charge plateau is seen, with no apparent change in the discharge behaviour. The kinetics of sodium insertion and extraction are discussed utilizing CV and EIS techniques. We also report the sodium chemical diffusion coefficient of the Na 2 Ti 3 O 7 /CB electrode estimated using GITT.

The ultra-fast (30C or 2 min) rate capability and impressive long cycle life (>5000 cycles) of Na2Ti6O13 are reported. A stable 2.5 V sodium-ion battery full cell is demonstrated. In addition, the sodium storage mechanism and thermal stability of Na2Ti6O13 are discussed.

There is no doubt that rechargeable batteries will play a huge role in the future of the world. Sodium-ion (Na-ion) batteries might be the ideal middle-ground between high performance delivered...

One of the key requirements of large-scale grid-storage systems is development of inexpensive and safe batteries. Sodium-ion batteries using earth-abundant Fe or Ti based cathodes and anodes would be ideal candidates for such storage systems. Herein, a new phase of Na-rich and all Fe Prussian Blue Analogue, monoclinic Na2Fe2(CN)6.2H2O, is reported as a potential cathode for such grid-storage sodium-ion batteries. This water-insoluble and air-stable cathode can deliver 85 mAh g−1 at an average discharge voltage of 3 V vs Na/Na+ with excellent cycle life (3,000 cycles). Many facets about its sodium storage characteristics are discussed with particular emphasis on the role of interstitial water on the sodium storage performance and its conversion to the dehydrated rhombohedral phase. Its compatibility with a newly developed non-flammable glyme-based liquid electrolyte, 1M NaBF4 in tetraglyme, is also disclosed along with general electrochemical and thermal characterization of this electrolyte for sodium-ion battery application. Finally, three different types of full cells are revealed with either monoclinic or rhombohedral phase as cathode and graphite or the recently reported Na2Ti3O7 ⇋ Na3-xTi3O7 pathway of Na2Ti3O7 as anode. Full cell energy densities of 70–90 Wh kg−1 (using cumulative cathode and anode weights) could be obtained without any pre-cycling steps. This new cathode and safe electrolyte may hold great promise toward development of inexpensive, non-flammable and highly stable grid-storage sodium-ion batteries.