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Abstract: Aqueous Zn‐ion batteries (ZIBs) have received incremental attention because of their cost‐effectiveness and the materials abundance. They are a promising choice for large‐scale energy storage applications. However, developing suitable cathode materials for ZIBs remains a great challenge. In this work, pioneering work on the designing and construction of aqueous Zn//Na0.33V2O5 batteries is reported. The Na0.33V2O5 (NVO) electrode delivers a high capacity of 367.1 mA h g−1 at 0.1 A g−1, and exhibits long‐term cyclic stability with a capacity retention over 93% for 1000 cycles. The improvement of electrical conductivity, resulting from the intercalation of sodium ions between the [V4O12]n layers, is demonstrated by single nanowire device. Furthermore, the reversible intercalation reaction mechanism is confirmed by X‐ray diffraction, Raman, X‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The outstanding performance can be attributed to the stable layered structure and high conductivity of NVO. This work also indicates that layered structural materials show great potential as the cathode of ZIBs, and the indigenous ions can act as pillars to stabilize the layered structure, thereby ensuring an enhanced cycling stability. [ABSTRACT FROM AUTHOR]

Hard carbon is one of the most promising anode materials for sodium-ion batteries, but the low Coulombic efficiency is still a key barrier. In this paper, a series of nanostructured hard carbon materials with controlled architectures is synthesized. Using a combination of in situ X-ray diffraction mapping, ex situ nuclear magnetic resonance (NMR), electron paramagnetic resonance, electrochemical techniques, and simulations, an 'adsorption-intercalation' mechanism is established for Na ion storage. During the initial stages of Na insertion, Na ions adsorb on the defect sites of hard carbon with a wide adsorption energy distribution, producing a sloping voltage profile. In the second stage, Na ions intercalate into graphitic layers with suitable spacing to form NaC x compounds similar to the Li ion intercalation process in graphite, producing a flat low voltage plateau. The cation intercalation with a flat voltage plateau should be enhanced and the sloping region should be avoided. Guided by this knowledge, nonporous hard carbon material has been developed which has achieved high reversible capacity and Coulombic efficiency to fulfill practical application. [ABSTRACT FROM AUTHOR]

Sodium storage in both solid-liquid and solid-solid interfaces is expected to extend the horizon of sodium-ion batteries, leading to a new strategy for developing high-performance energy-storage materials. Here, a novel composite aerogel with porous Li4Ti5O12 (PLTO) nanofibers confined in a highly conductive 3D-interconnected graphene framework (G-PLTO) is designed and fabricated for Na storage. A high capacity of 195 mA h g-1 at 0.2 C and super-long cycle life up to 12 000 cycles are attained. Electrochemical analysis shows that the intercalation-based and interfacial Na storage behaviors take effect simultaneously in the G-PLTO composite aerogel. An integrated Na storage mechanism is proposed. This study ascribes the excellent performance to the unique structure, which not only offers short pathways for Na+ diffusion and conductive networks for electron transport, but also guarantees plenty of PLTO-electrolyte and PLTO-graphene interfacial sites for Na+ adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • A spray-draying route is adopted to synthesize Na 3 V 2 (PO 4) 2 F 3 /C (NVPF/C). • A Na-ion full cell is designed with NVPF and HC anode addressed by pre-sodiation. • NVPF-HC (D100) shows the optimal Na-ion storage capability. • HC pre-sodiation degree dependent Na-ion battery performance is proofed. Sodium-ion battery has been put into an eager consideration in the large-scale energy storage system, owing to its inexpensive cost ($/kWh) than that of the lithium-ion battery. The gap from research to industry still exists, however, including low energy density and unsatisfactory cycling lifespan in full cells. Here we report a Na-ion full cell with spray-dried Na 3 V 2 (PO 4) 2 F 3 /C (NVPF/C) cathode and pre-sodiated hard carbon (HC) anode. It is demonstrated that the full cells (NVPF-HC), assembled with 100% presodiated HC anode, exhibits the best energy storage capability and rate performance. A remarkable reversible capacity of 114.1 mA h g−1 at 0.5C (attaining 95% of capacity for NVPF-Na anode half-cell), a desirable power performance with 90.6 mA h g−1 at a high rate of 20C, and an impressive cycling life (71.8% capacity retention after 600 cycles at 10C) are achieved. The outstanding battery performance is ascribed to that the electroactivity Na+ in HC can maximize the scavenger effect and forms the more stable solid-electrolyte interface (SEI). Moreover, an HC pre-sodiation degree dependent Na-ion battery performance is proofed. The findings in this paper offer new insights on the electrode design strategy, which facilitates the development of sodium-ion technology. [ABSTRACT FROM AUTHOR]