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Hybrid sodium-ion capacitors (NICs) have tremendous potential in large-scale energy storage applications due to their low cost, long lifetime and high power. However, it remains a great challenge to find a desirable anode material with fast kinetics and superior cycle life. Here an applicable strategy to in situ grow Na2Ti3O7 on 1D CNTs as an anode material for sodium-ion capacitors is presented. Benefiting from the unique 1D nanostructure and the presence of pseudocapacitive charge storage mechanism, the Na2Ti3O7@CNT electrode exhibits excellent electrochemical performance with high rate capability and superb cycling stability. Moreover, a high performance hybrid NIC is also fabricated by using Na2Ti3O7@CNTs as an anode and activated carbon derived from the outer peanut shell as a cathode, which delivers high energy density (58.5 W h kg−1), high power density (3000 W kg−1), and long term cycle life (retaining ca. 75% of its original capacity at 0.4 A g−1 after 4000 cycles). [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) working at room temperature offer promising opportunities for renewable energy storage applications because of the abundant supply and low cost of sodium, low capacity, inferior rate capability and limited cycle life remain a significant challenge in their electrochemical operations. Herein, we report the preparation of hierarchically Na3V2(PO4)3/nitrogen-decorated carbon hybrids via solvothermal reaction using biomolecule of adenosine 5′-triphosphate disodium salt (ATP), as a novel precursor and environmentally friendly multifunctional source, simultaneously including sodium, phosphorus, carbon, nitrogen. The results demonstrate that Na3V2(PO4)3 nanocrystals are encapsulated in interconnected carbon nanosheets with moderate nitrogen doping (2.88%) to form a bundle-like structure, where the carbon nanosheets not only serve as a highly conducting pathway facilitating electron and ion transport, but as a shielding matrix to accommodate volume changes upon electrochemical cycling; thus, improving stability and reversibility of the Na3V2(PO4)3 cathode. Thus, the obtained materials deliver a high reversible capacity of 110.9 mA h g−1 at a low current rate of 0.2 C, as well as outstanding rate performance, suggesting that the Na3V2(PO4)3/nitrogen-doped carbon hybrids are promising cathode materials to be used in high-performance sodium ion batteries. [ABSTRACT FROM AUTHOR]